Disorders of Motor Function

Disorders of Motor Function

Motor Cortex Highest level of motor function
Precise, skillful, intentional movements Speech, flexor muscles of limbs, etc. Controlled by the primary, premotor and supplementary motor cortices in the frontal lobe from the Thalamus, cerebellum and basal ganglia Motor humunculus

Motor Cortex Primary motor cortex Premotor cortex (areas 6 and 8)
Responsible for execution of a movement. Adjacent to central sulcus Motor Humunculus Premotor cortex (areas 6 and 8) Generates intricate plan of movement. Throwing a ball or picking up a fork

Motor Cortex Supplementary motor cortex
Involved in the performance of complex, skillful movements (areas 6 and 8)

Homunculus

Basal Ganglia A group of deep, interrelated subcortical nuclei that play an essential role in control of movement Receives indirect input from the cerebellum and from all sensory systems, including vision, and direct input from the motor cortex Functions in the organization of inherited and highly learned and rather automatic movement programs Also involved in cognitive and perception functions

Structural Components of the Basal Ganglia
Caudate nucleus Putamen Globus pallidus in the forebrain Substantia Nigra (midbrain) Subthalamic nucleus

Structural Components of the Basal Ganglia
Caudate + Putamen = Striatum Putamen + Globus Pallidus = Lentiform nucleus

Motor System Overview Cortex sends messages to the caudate and putamen of the basal ganglia Acts on the Thalamus Then to the supplementary motor cortex for review and editing Then to the primary motor cortex, premotor cortex and primary somatosensory cortex Then to the brain stem and spinal cord The cerebellum – ensures the desired movements occur smoothly The cerebellum receives ongoing information from the motor cortex and runs a comparison between it and the actual movement in the muscles, tendons and joints. This information is ongoing. The cerebellum alters the information by either reducing or increasing its inhibition of the brain stem and motor nuclei. If the basal ganglia do not produce a functioning signal movement is slowed or frozen = Parkinson’s Disease.

Basal Ganglia Basal Ganglia monitors sensory information coming into the brain sends it to the right place to be stored as a memory

Four Functional Pathways Involving Basal Ganglia
A dopamine pathway from the substantia nigra to the striatum A γ-aminobutyric acid (GABA) pathway from the striatum to the globus pallidus and substantia nigra Acetylcholine-secreting neurons, which are important in networks within the neostriatum Multiple general pathways from the brain stem that secrete norepinephrine, serotonin, enkephalin, and several other neurotransmitters in the basal ganglia and the cerebral cortex

Thalamus It relays to the cerebral cortex information received from other regions of the brain and spinal cord. Sends information down spinal cord to the body a brain “switching station”

Thalamus The cerebral cortex is interconnected with the Thalamus
Excitatory circuit If unmodulated would cause hyperactivity = stiffness and rigidity with a continuous tremor (tremor at rest) Basal Ganglia modulates the Thalamic excitability by an inhibitory loop

Receives sensory information from the peripheral parts of the body
The cerebellum receives continuous information about the sequence of muscle contractions from the brain Receives sensory information from the peripheral parts of the body Proprioception sequential changes in the status of each body part

Brain Stem Midbrain Pons
Associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation Pons Nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture

Brain Stem Medulla Contains the cardiac, respiratory, vomiting and vasomotor centers dealing with autonomic, involuntary functions Breathing, heart rate and blood pressure

Spinal Cord Structure and Function
White Matter Pathways Myelinated axons surrounding gray matter = cell bodies and their synaptic interconnections Central Butterfly of Gray Matter Collections of motor neurons with related function in the anterior horns Sensory relay neurons in the posterior horn

Dorsal Ventral

Ascending (Sensory) Pathways
Anterolateral Spinothalamic Tract Carries information from pain, temperature and crude touch receptors to the thalamus (relay station of the brain) First neuron synapses in the dorsal horn Second neuron crosses the cord to the region ventral to the central canal and travels in the spinothalamic tract to the thalamus

Ascending Pathways

Ascending (Sensory) Pathways Dorsal Columns
Medial Leminiscal Pathways Carries information from the skin of the lower and upper limbs (light touch, vibration, ability to discriminate between adjacent stimuli, pressure) Carries information from shoulder, arm and finger on position and tension in muscles and tendons, movement, etc. Dorsal root ganglion to the cord, to the dorsal column of white matter, to a nucleus in the medulla to the thalamus to the cortex for conscious perception

Descending Pathway

Descending (Motor) Pathways
Lateral Corticospinal Tract (Pyramidal Tract) Carries movement signals from the cerebral cortex to the motor neurons in the spinal cord Crosses over in the medulla Travels down the cord in a lateral position Passes into the gray matter in the cord to synapse with the motor neuron

Descending (Motor) Pathway
Extrapyramidal Pathways (Multineuronal Pathways) Provides for the support of movements of the lateral corticospinal tract Movements of the trunk, proximal limb muscles, balance, posture, orienting to sight or sound and more.

Pyramidal motor system Originates in the motor cortex
Controls all of our voluntary movements Consists of upper motor neurons in the Primary Motor Cortex and lower motor neurons in the anterior horn of the spinal cord Extrapyramidal motor system Originates in the basal ganglia Includes the substantia nigra, caudate, putamen, globus pallidus, thalamus, and subthalamic nucleus. Provides background for the more crude, supportive movement patterns

Amyotrophic Lateral Sclerosis (ALS)
Rapidly progressive weakness, muscle atrophy, spasticity, dysphagia Early symptoms: muscle weakness in an arm or leg, twitching, slurred speech Death within 2-3 years due to respiratory compromise Sensory and cognitive function are unaffected (upper motor neurons in cortex and/or lower motor neurons in cord/brainstem) Amyotrophic lateral sclerosis (ALS), also referred to as Lou Gehrig's disease, is a form of motor neuron disease (called motor neurone disease in Europe) caused by the degeneration of upper and lower neurons, located in the ventral horn of the spinal cord and the cortical neurons that provide their efferent input. The condition is often called Lou Gehrig's disease in North America, after the New York Yankees baseball player who was diagnosed with the disease in The disorder is characterized by rapidly progressive weakness, muscle atrophy and fasciculations, spasticity, dysarthria, dysphagia, and respiratory compromise. Sensory function generally is spared, as is autonomic, and oculomotor activity. ALS is a progressive,[1] fatal, neurodegenerative disease with most affected patients dying of respiratory compromise and pneumonia after 2 to 3 years; although some perish within a year from the onset of symptoms, and occasional individuals have a more indolent course and survive for many years. he disorder causes muscle weakness and atrophy throughout the body caused by degeneration of the upper and lower motor neurons. Unable to function, the muscles weaken and atrophy. Affected individuals may ultimately lose the ability to initiate and control all voluntary movement, although bladder and bowel sphincters and the muscles responsible for eye movement are usually, but not always, spared. Cognitive function is generally spared for most patients although some (~5%) also have frontotemporal dementia.[3] A higher proportion of patients (~30-50%) also have more subtle cognitive changes which may go unnoticed but are revealed by detailed neuropsychological testing. Sensory nerves and the autonomic nervous system, which controls functions like sweating, are generally unaffected but may be involved for some patients. [edit]Initial symptoms The earliest symptoms of ALS are typically obvious weakness and/or muscle atrophy. Other presenting symptoms include muscle fasciculation (twitching), cramping, or stiffness of affected muscles; muscle weakness affecting an arm or a leg; and/or slurred and nasal speech. The parts of the body affected by early symptoms of ALS depend on which motor neurons in the body are damaged first. About 75% of people contracting the disease experience "limb onset" ALS i.e. first symptoms in the arms ("upper limb", not to be confused with "upper motor neuron") or legs ("lower limb", not to be confused with "lower motor neuron"). Patients with the leg onset form may experience awkwardness when walking or running or notice that they are tripping or stumbling, often with a "dropped foot" which drags gently along the ground. Arm-onset patients may experience difficulty with tasks requiring manual dexterity such as buttoning a shirt, writing, or turning a key in a lock. Occasionally, the symptoms remain confined to one limb for a long period of time or for the whole length of the illness; this is known as monomelic amyotrophy. About 25% of cases are "bulbar onset" ALS. These patients first notice difficulty speaking clearly or swallowing. Speech may become slurred, nasal in character, or quieter. Other symptoms include difficulty swallowing, and loss of tongue mobility. A smaller proportion of patients experience "respiratory onset" ALS where the intercostal muscles that support breathing are affected first. Regardless of the part of the body first affected by the disease, muscle weakness and atrophy spread to other parts of the body as the disease progresses. Patients experience increasing difficulty moving, swallowing (dysphagia), and speaking or forming words (dysarthria). Symptoms of upper motor neuron involvement include tight and stiff muscles (spasticity) and exaggerated reflexes (hyperreflexia) including an overactive gag reflex. An abnormal reflex commonly called Babinski's sign (the big toe extends upward and other toes spread out) also indicates upper motor neuron damage. Symptoms of lower motor neuron degeneration include muscle weakness and atrophy, muscle cramps, and fleeting twitches of muscles that can be seen under the skin (fasciculations). Around 15–45% of patients experiencepseudobulbar affect, also known as "emotional lability", which consists of uncontrollable laughter, crying or smiling, attributable to degeneration of bulbar upper motor neurons resulting in exaggeration of motor expressions of emotion. To be diagnosed with ALS, patients must have signs and symptoms of both upper and lower motor neuron damage that cannot be attributed to other causes. [edit]Disease progression Although the sequence of emerging symptoms and the rate of disease progression vary from person to person, eventually most patients are not able to stand or walk, get in or out of bed on their own, or use their hands and arms. Difficulty swallowing and chewing impair the patient's ability to eat normally and increase the risk of choking or aspirating food/liquids into the lungs. Aspiration pneumonia and weight maintenance can then become a problem. Because the disease usually does not affect cognitive abilities, patients are aware of their progressive loss of function and may become anxious and depressed. A small percentage of patients go on to develop frontotemporal dementia characterized by profound personality changes; this is more common among those with a family history of dementia. A larger proportion of patients experience mild problems with word-generation, attention, or decision-making. Cognitive function may be affected as part of the disease process or could be related to poor breathing at night (nocturnal hypoventilation). Health care professionals need to explain the course of the disease and describe available treatment options so that patients can make informed decisions in advance. As the diaphragm and intercostal muscles (rib cage) weaken, forced vital capacity and inspiratory pressure diminish. In bulbar onset ALS, this may occur before significant limb weakness is apparent. Bilevel positive pressure ventilation (frequently referred to by the tradename BiPAP) is frequently used to support breathing, first at night, and later during the daytime as well. It is recommended that long before BiPAP becomes insufficient, patients must decide whether to have a tracheostomy and long term mechanical ventilation. At this point, some patients choose palliative hospice care. Most people with ALS die of respiratory failure or pneumonia. Death usually occurs within two to five years of diagnosis. Although the disease can strike at any age, most people are between forty and seventy years of age when the disease strikes and men are affected slightly more frequently than women. An estimated 5,000 people in the United States are diagnosed with the disease each year.[4] ALS, a progressive disease, leads to death in half of the people diagnosed within three years and ninety percent within six years. In a population based study in Minnesota, USA, looking back over 85 years, 14 percent of people with ALS survived more than 5 years. Those who survived 5 years or longer were clinically similar to the total population ALS population in terms of gender, age, gender, and site of onset, but they had a longer time from symptomatic onset to time of diagnosis [5] ALS predominantly affects the motor neurons, and in the majority of cases the disease does not impair a patient's mind, personality, intelligence, or memory. Nor does it affect a person's ability to see, smell, taste, hear, or feel touch. Control of eye muscles is the most preserved function, although some patients with an extremely long duration of disease (20+ years) may lose eye control too. Unlike multiple sclerosis, bladder and bowel control are usually preserved in ALS, although as a result of immobility and diet changes, intestinal problems such as constipation can require intensive management. [edit]Cause For patients without a family history of the disease, which includes ~95% of cases, there is no known cause for ALS. There is a known hereditary factor in familial ALS (FALS), where the condition is known to run in families, although this accounts for only around 5% of all cases. An inherited genetic defect on chromosome 21 (coding for superoxide dismutase) is associated with approximately 20% of familial cases of ALS.[6][7] This mutation is believed to be autosomal dominant. The most common ALS causing SOD1 mutation in North America is A4V, characterized by an exceptionally rapid progression from onset to death. The children of those diagnosed with familial ALS have a higher risk factor for developing the disease; however, those who have close family members who have been diagnosed with sporadic ALS have no greater a risk factor than the general population, suggesting again an environmental or other non-genetic cause.[8] Some environmental causative factors have been suggested for the increased incidence in the western Pacific. Prolonged exposure to a dietary neurotoxin called BMAA is one suspected risk factor in Guam;[9] this neurotoxin produced by cyanobacteria is one of several possible neurotoxic compounds found in the seed of the cycad Cycas circinalis,[10] a tropical plant found in Guam, which was used in the human food supply during the 1950s and early 1960s. The very high incidence of the disease among Italian soccer players (more than five times higher than normally expected) has raised the concern of a possible link between the disease and the use of pesticides on the soccer fields (several of which have been linked to neuronal toxicity).[11][12] A 2004 Italian study trying to link a high incidence of ALS in soccer players to performance-enhancing drugs failed when the group was compared to cyclists that also used performance-enhancing drugs but without contracting ALS. A possible conclusion was that soccer players experience frequent head trauma (heading the ball, falls and collisions sustained during games) compared to cyclists who wear head protection and rarely have falls.[13][14] According to the ALS Association, veterans of the United States military are at an increased risk of contracting ALS (again, possibly implying a link to neurotoxic chemical exposure). In its report ALS in the Military,[15] the group pointed to an almost 60% greater chance of the disease in military veterans than the general population. For Gulf War veterans, the chance is seen as twice that of veterans not deployed to the Persian Gulf in a joint study by the Veterans Affairs Administration and the DOD, another epidemiologic association suggesting a link to toxic exposure.[16][17][18] A 2010 study has raised questions about the diagnosis of ALS in some veterans and athletes, suggesting that repeated concussions may cause a chronic traumatic encephalopathy that mimics ALS; this might explain the higher rate of ALS diagnoses in those populations.[unreliable medical source?][19] [edit]Pathophysiology Genetic associations include Type OMIM Gene Locus ALS1 105400 SOD1 21q22.1 ALS2 205100 2q33.1 ALS3 606640 ? 18q21 ALS4 602433 SETX 9q34.13 ALS5 602099 15q15.1-q21.1 ALS6 608030 FUS 16p11.2 ALS7 608031 20p13 ALS8 608627 VAPB 20q13.3 ALS9 611895 ANG 14q11.2 ALS10 612069 TARDBP 1p36.2 ALS11 612577 FIG4 6q21 ALS12 613435 OPTN 10p15-p14 ALS13 183090 ATXN2 12q24.12 ALS14 613954 VCP 9p13.3 The defining feature of ALS is the death of both upper and lower motor neurons in the motor cortex of the brain, the brain stem, and the spinal cord. Prior to their destruction, motor neurons develop proteinaceous inclusions in their cell bodies and axons. This may be partly due to defects in protein degradation.[20] These inclusions often contain ubiquitin, and generally incorporate one of the ALS-associated proteins: SOD1, TAR DNA binding protein(TDP-43, or TARDBP), or FUS. Interestingly, these inclusions do not stain with the dyes Congo Red or Thioflavin S, and are therefore non-amyloid aggregates.[21][22] This is in contrast to the aggregates and plaques seen in many other neurodegenerative diseases of protein aggregation, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and prion diseases. [edit]SOD1 The cause of ALS is not known, though an important step toward determining the cause came in 1993 when scientists discovered that mutations in the gene that produces the Cu/Zn superoxide dismutase (SOD1) enzyme were associated with some cases (approximately 20%) of familial ALS. This enzyme is a powerful antioxidant that protects the body from damage caused by superoxide, a toxic free radical generated in the mitochondria. Free radicalsare highly reactive molecules produced by cells during normal metabolism again largely by the mitochondria. Free radicals can accumulate and cause damage to both mitochondrial and nuclear DNA and proteins within cells. To date, over 110 different mutations in SOD1 have been linked with the disease, some of which have a very long clinical course (e.g. H46R), while others, such as A4V, being exceptionally aggressive. Evidence suggests that failure of defenses against oxidative stress up-regulates programmed cell death (apoptosis), among many other possible consequences. Although it is not yet clear how the SOD1 gene mutation leads to motor neuron degeneration, researchers have theorized that an accumulation of free radicals may result from the faulty functioning of this gene. Current research, however, indicates that motor neuron death is not likely a result of lost or compromised dismutase activity, suggesting mutant SOD1 induces toxicity in some other way (a gain of function).[23][24] Studies involving transgenic mice have yielded several theories about the role of SOD1 in mutant SOD1 familial amyotrophic lateral sclerosis. Mice lacking the SOD1 gene entirely do not customarily develop ALS, although they do exhibit an acceleration of age-related muscle atrophy (sarcopenia) and a shortened lifespan (see article on superoxide dismutase). This indicates that the toxic properties of the mutant SOD1 are a result of a gain in function rather than a loss of normal function. In addition, aggregation of proteins has been found to be a common pathological feature of both familial and sporadic ALS (see article on proteopathy). Interestingly, in mutant SOD1 mice (most commonly, the G93A mutant), aggregates (misfolded protein accumulations) of mutant SOD1 were found only in diseased tissues, and greater amounts were detected during motor neuron degeneration.[25] It is speculated that aggregate accumulation of mutant SOD1 plays a role in disrupting cellular functions by damaging mitochondria, proteasomes, protein folding chaperones, or other proteins.[26] Any such disruption, if proven, would lend significant credibility to the theory that aggregates are involved in mutant SOD1 toxicity. Critics have noted that in humans, SOD1 mutations cause only 2% or so of overall cases and the etiological mechanisms may be distinct from those responsible for the sporadic form of the disease. To date, the ALS-SOD1 mice remain the best model of the disease for preclinical studies but it is hoped that more useful models will be developed. [edit]Lactate Dyscrasia Hypothesis Researchers specializing in the neurobiology of aging have proposed a novel molecular model for the pathogenesis of ALS called the lactate dyscrasia hypothesis that involves an adenosine triphosphate (ATP)-dependent muscle neuronal lactate shuttle (MNLS) at theneuromuscular junction (NMJ) to regulate the flow of lactate from muscle to neurons and vice versa. Failure of the MNLS due to respiratory chain dysfunction is proposed to result in lactate toxicity and degeneration of nerve endings at the NMJ leading to nerve terminus dysjunction from the muscle cell.[27] [edit]Other factors Studies also have focused on the role of glutamate in motor neuron degeneration. Glutamate is one of the chemical messengers or neurotransmitters in the brain. Scientists have found that, compared to healthy people, ALS patients have higher levels of glutamate in theserum and spinal fluid.[7] Riluzole is currently the only FDA approved drug for ALS and targets glutamate transporters. It only has a modest effect on survival, however, suggesting that excess glutamate is not the sole cause of the disease. [edit]Diagnosis No test can provide a definite diagnosis of ALS, although the presence of upper and lower motor neuron signs in a single limb is strongly suggestive. Instead, the diagnosis of ALS is primarily based on the symptoms and signs the physician observes in the patient and a series of tests to rule out other diseases. Physicians obtain the patient's full medical history and usually conduct a neurologic examination at regular intervals to assess whether symptoms such as muscle weakness, atrophy of muscles, hyperreflexia, and spasticity are getting progressively worse. MRI (axial FLAIR) demonstrates increased T2 signal within the posterior part of the internal capsule, consistent with the clinical diagnosis of ALS. Because symptoms of ALS can be similar to those of a wide variety of other, more treatable diseases or disorders, appropriate tests must be conducted to exclude the possibility of other conditions. One of these tests iselectromyography (EMG), a special recording technique that detects electrical activity in muscles. Certain EMG findings can support the diagnosis of ALS. Another common test measures nerve conduction velocity (NCV). Specific abnormalities in the NCV results may suggest, for example, that the patient has a form of peripheral neuropathy (damage to peripheral nerves) or myopathy (muscle disease) rather than ALS. The physician may order magnetic resonance imaging (MRI), a noninvasive procedure that uses a magnetic field and radio waves to take detailed images of the brain and spinal cord. Although these MRI scans are often normal in patients with ALS, they can reveal evidence of other problems that may be causing the symptoms, such as a spinal cord tumor, multiple sclerosis, a herniated disk in the neck, syringomyelia, or cervical spondylosis. Based on the patient's symptoms and findings from the examination and from these tests, the physician may order tests on blood and urine samples to eliminate the possibility of other diseases as well as routine laboratory tests. In some cases, for example, if a physician suspects that the patient may have a myopathy rather than ALS, a muscle biopsy may be performed. Infectious diseases such as human immunodeficiency virus (HIV), human T-cell leukaemia virus (HTLV), Lyme disease,[28] syphilis[29] and tick-borne encephalitis[30] viruses can in some cases cause ALS-like symptoms. Neurological disorders such as multiple sclerosis, post-polio syndrome, multifocal motor neuropathy, CIDP, and spinal muscular atrophy can also mimic certain facets of the disease and should be considered by physicians attempting to make a diagnosis. Because of the prognosis carried by this diagnosis and the variety of diseases or disorders that can resemble ALS in the early stages of the disease, patients should always obtain a second neurological opinion. [edit]Treatment [edit]Slowing progression Riluzole (Rilutek) as of 2011 is the only treatment that has been found to improve survival but only to a modest extent.[31] It lengthens survival by several months, and may have a greater survival benefit for those with a bulbar onset. It also extends the time before a person needs ventilation support. Riluzole does not reverse the damage already done to motor neurons, and people taking it must be monitored for liver damage (occurring in ~10% of people taking the drug).[32] It is approved by Food and Drug Administration (FDA) and recommended by the National Institute for Clinical Excellence (NICE). [edit]Symptomatic Other treatments for ALS are designed to relieve symptoms and improve the quality of life for patients. This supportive care is best provided by multidisciplinary teams of health care professionals such as physicians; pharmacists; physical, occupational, and speech therapists; nutritionists; social workers; and home care and hospice nurses. Working with patients and caregivers, these teams can design an individualized plan of medical and physical therapy and provide special equipment aimed at keeping patients as mobile and comfortable as possible. Medical professionals can prescribe medications to help reduce fatigue, ease muscle cramps, control spasticity, and reduce excess saliva and phlegm. Drugs also are available to help patients with pain, depression, sleep disturbances, dysphagia, and constipation. Physical therapists and occupational therapists play a large role in rehabilitation for individuals with ALS. Specifically, physical and occupational therapists can set goals and promote benefits for individuals with ALS by delaying loss of strength, maintaining endurance, limiting pain, preventing complications, and promoting functional independence.[33] There is also a strong emphasis on the importance of patient and caregiver education that can be reinforced by physical therapists or occupational therapists.[33] Research is controversial as to whether implementing a specific exercise program for these individuals may be beneficial; moreover, it is important for a physical therapist to address and understand the risks associated with implementing these types of programs for each and every person with ALS and the severity of their condition. The controversy lies in the fact that because ALS is characteristic of the degeneration of upper and lower motor neurons, that these neurons may react differently to specific exercise programs.[33] Because spasticity is a common characteristic for individuals with ALS, physical therapists aim to reduce this by implementing range of motion activities with minimal resistance.[33] In addition to range of motion activities, positioning techniques and splinting have also been shown to reduce spasticity; moreover, these techniques can also play an integral role in the reduction of pain for people with ALS.[33] Overall, physical therapists have been proven to have positive effects on individuals with ALS by prescribing techniques and equipment to assist with conserving energy, emphasizing the importance of education, limiting pain, and help to maintain a level of function appropriate for each of their clients with ALS.[33] Occupational therapy and special equipment such as assistive technology can also enhance patients' independence and safety throughout the course of ALS. But physical therapists must be mindful when prescribing assistive devices, keeping in mind the patients and their attitudes. Devices should make the patient feel hopeful, not helpless. Gentle, low-impact aerobic exercise such as walking, swimming, and stationary bicycling can strengthen unaffected muscles, improve cardiovascular health, and help patients fight fatigue and depression. Range of motion and stretching exercises can help prevent painful spasticity and shortening (contracture) of muscles. Physical therapists can recommend exercises that provide these benefits without overworking muscles. They can suggest devices such as ramps, braces, walkers, and wheelchairs that help patients remain mobile. Examples of devices prescribed can include cervical collars.[34] In ALS, there will be a progression of cervical extensor weakness.[34] Weakness of the muscles will cause the patient's head to fall forward, leading to acute neck pain, potential for chronic cervical conditions to develop and tightness of anterior neck muscles.[34] A forward head posture will interfere in patients ADLs, making them more dependent on caretakers. A cervical collar can help restore their independence and comfort. When there is mild to moderate weakness of the cervical extensor, the therapist may provide a soft foam collar.[34] When more severe weakness is observed, a more rigid collar will be beneficial.[34] Occupational therapists can provide or recommend equipment and adaptations to enable people to retain as much independence in activities of daily living as possible. ALS patients who have difficulty speaking may benefit from working with a speech-language pathologist. These health professionals can teach patients adaptive strategies such as techniques to help them speak louder and more clearly. As ALS progresses, speech-language pathologists can recommend the use of augmentative and alternative communication such as voice amplifiers, speech-generating devices (or voice output communication devices) and/or low tech communication techniques such as alphabet boards or yes/no signals. These methods and devices help patients communicate when they can no longer speak or produce vocal sounds. With the help of occupational therapists, speech-generating devices can be activated by switches or mouse emulation techniques controlled by small physical movements of, for example, the head, finger or eyes. In every case, the appropriate therapist should be mindful of the patients' preferences, attitudes, and likely progression over time. Patients and caregivers can learn from speech-language pathologists and nutritionists how to plan and prepare numerous small meals throughout the day that provide enough calories, fiber, and fluid and how to avoid foods that are difficult to swallow. Patients may begin using suction devices to remove excess fluids or saliva and prevent choking. When patients can no longer get enough nourishment from eating, doctors may advise inserting a feeding tube into the stomach. The use of a feeding tube also reduces the risk of choking and pneumonia that can result from inhaling liquids into the lungs. The tube is not painful and does not prevent patients from eating food orally if they wish. When the muscles that assist in breathing weaken, use of ventilatory assistance (intermittent positive pressure ventilation (IPPV), bilevel positive airway pressure (BIPAP), or biphasic cuirass ventilation (BCV)) may be used to aid breathing. Such devices artificially inflate the patient's lungs from various external sources that are applied directly to the face or body. When muscles are no longer able to maintain oxygen and carbon dioxide levels, these devices may be used full-time. BCV has the added advantage of being able to assist in clearing secretions by using high-frequency oscillations followed by several positive expiratory breaths.[35] Patients may eventually consider forms of mechanical ventilation (respirators) in which a machine inflates and deflates the lungs. To be effective, this may require a tube that passes from the nose or mouth to the windpipe (trachea) and for long-term use, an operation such as a tracheostomy, in which a plastic breathing tube is inserted directly in the patient's windpipe through an opening in the neck. Patients and their families should consider several factors when deciding whether and when to use one of these options. Ventilation devices differ in their effect on the patient's quality of life and in cost. Although ventilation support can ease problems with breathing and prolong survival, it does not affect the progression of ALS. Patients need to be fully informed about these considerations and the long-term effects of life without movement before they make decisions about ventilation support. Some patients under long-term tracheostomy intermittent positive pressure ventilation with deflated cuffs or cuffless tracheostomy tubes (leak ventilation) are able to speak, provided their bulbar muscles are strong enough. This technique preserves speech in some patients with long-term mechanical ventilation. Social workers and home care and hospice nurses help patients, families, and caregivers with the medical, emotional, and financial challenges of coping with ALS, particularly during the final stages of the disease. Social workers provide support such as assistance in obtaining financial aid, arranging durable power of attorney, preparing a living will, and finding support groups for patients and caregivers. Home nurses are available not only to provide medical care but also to teach caregivers about tasks such as maintaining respirators, giving feedings, and moving patients to avoid painful skin problems and contractures. Home hospice nurses work in consultation with physicians to ensure proper medication, pain control, and other care affecting the quality of life of patients who wish to remain at home. The home hospice team can also counsel patients and caregivers about end-of-life issues. Researchers have stated that "ALS patients have a chronically deficient intake of energy and recommended augmentation of energy intake."[36] Both animal [37] and human research [36][38] suggest that ALS patients should be encouraged to consume as many calories as possible and not to restrict their calorie intake. Many ALS patients use complementary and alternative medicines in an attempt to slow their disease.[citation needed] This may include popular vitamin supplements such as Vitamin C, high doses of vitamins and nutrients ("mega-dosing"), traditional Chinese medicine, or other forms of therapy such as acupuncture, reiki, or massage. To date there have been no studies demonstrating that such treatment approaches have an effect on the progression of the disease. Given the lack of therapeutic options, people with ALS can be vulnerable tosnake oil scams involving complicated medical terminology or potentially exciting technologies such as stem cell transplantation. Practitioners of these scams promise amazing results but carry out little or no real follow up or study of the patients they have treated in order to prove their assertions. The risks of false hope, financial harm, and potentially medically harm, are a threat to the wellbeing of ALS patients and their families. [edit]Prognosis Eventually most people with ALS are not able to stand or walk, get in or out of bed on their own, use their hands and arms, or communicate. In later stages of the disease, individuals have difficulty breathing as the muscles of the respiratory system weaken. Although respiratory support can ease problems with breathing and prolong survival, it does not affect the progression of ALS. Most people with ALS die from respiratory failure, usually within three to five years from the onset of symptoms. The median survival time from onset to death ranges from 20 to 48 months, but 10 to 20% of ALS patients have a survival longer than 10 years.[39] The world's most widely recognized person with ALS, Stephen Hawking, has lived with the disease for more than 40 years, though his is an unusual case.[40] [edit]Epidemiology ALS is one of the most common neuromuscular diseases worldwide, and people of all races and ethnic backgrounds are affected. One or two out of 100,000 people develop ALS each year.[41] ALS most commonly strikes people between 40 and 60 years of age, but younger and older people can also develop the disease. Men are affected slightly more often than women. "Familial ALS" accounts for approximately 5%–10% of all ALS cases and is caused by genetic factors. Of these, approximately 1 in 10 is linked to a mutation in copper/zinc superoxide dismutase (SOD1), an enzyme responsible for scavenging free radicals. A recent study has identified a gene called FUS ("Fused in Sarcoma", ALS6) as being responsible for 1 in 20 cases of fALS.[42][43] Although the incidence of ALS is thought to be regionally uniform, there are three regions in the West Pacific where there has in the past been an elevated occurrence of ALS. This seems to be declining in recent decades. The largest is the area of Guam inhabited by theChamorro people, who have historically had a high incidence (as much as 143 cases per 100,000 people per year) of a condition called Lytico-Bodig disease which is a combination of ALS, Parkinsonism, and dementia.[44] Two more areas of increased incidence are West Papua and the Kii Peninsula of Japan.[45][46] Although there have been reports of several "clusters" including three American football players from the San Francisco 49ers, more than fifty football players in Italy,[11] three football-playing friends in the south of England,[47] and reports of conjugal (husband and wife) cases in the south of France,[48][49][50][51][52] these are statistically plausible chance events[citation needed]. Although many authors consider ALS to be caused by a combination of genetic and environmental risk factors, so far the latter have not been firmly identified, other than a higher risk with increasing age. In 2010, a VA study found that head trauma can produce symptoms that resemble ALS but that are actually chronic traumatic encephalopathy (CTE). Postmortem brain studies conducted on two American football players showed evidence of CTE, rather than ALS.[53] [edit]Etymology Amyotrophic comes from the Greek language: A- means "no", myo refers to "muscle", and trophic means "nourishment"; amyotrophic therefore means "no muscle nourishment," which describes the characteristic atrophication of the sufferer's disused muscle tissue. Lateralidentifies the areas in a person's spinal cord where portions of the nerve cells that are affected are located. As this area degenerates it leads to scarring or hardening ("sclerosis") in the region. [edit]History -- THE HYPOTHESIS An accumulation of neural proteins causes Lou Gehrig’s disease. THE INVESTIGATOR Dr. Teepu Siddique, Northwestern University. Ever since the New York Yankees Hall of Famer Lou Gehrig benched himself in 1939, never to return to the game, the ailment that now bears his name has stoked dread in the American imagination. Lou Gehrig’s disease — also known as amyotrophic lateral sclerosis, orA.L.S. — has afflicted well-known figures like the jazz great Charles Mingus, the physicist Stephen Hawking and the historian Tony Judt. The disease stems from the progressive deterioration of nerve cells, leading to a loss of control over voluntary muscles, difficulty breathingand swallowing, creeping paralysis and eventually death. There is no cure and no good treatment. Scientists are still unsure exactly what causes most cases. But in the journal Nature last week, researchers at Northwestern University identified a possible culprit: a cellular housekeeping agent that normally helps cells to clear away proteins that are damaged or misfolded. When the housekeeper fails, proteins seem to aggregate inside nerve cells, which may be contributing to their destruction. The finding has been hailed as a breakthrough by patient groups and scientists. The new work is “fueling great enthusiasm and interest,” said Dr. Amelie Gubitz of the National Institute of Neurological Disorders and Stroke, which helped finance the new work. Still, it is far from clear that this is the wellspring of A.L.S. There are at least a dozen processes that also might contribute to the demise of motor nerve cells, Dr. Gubitz noted. Scientists are investigating, for example, defects in cellular mitochondria, which are responsible for producing energy. They are researching problems with the neurotransmitter glutamate, which seems to overstimulate cells in A.L.S., causing toxicity. They are looking into abnormalities in the motor axons that run from nerve cell bodies to the junctions with muscles they cause to contract. It’s possible that one of these might prove more important — or more amenable to treatment — than the others, Dr. Gubitz said. “We don’t know that yet,” she added. “We still need to pursue all of them.” Yet there is growing evidence for the hypothesis that that defective protein clearance plays a pivotal role in A.L.S. In the early 1990s, Dr. Siddique helped to discover mutations in a gene called SOD1 associated with some inherited forms of the disease. He and other researchers have since identified a variety of other mutations relevant to A.L.S. “The problem is that these mutations pertain to a very small number of patients,” he said in an interview. Only 5 to 10 percent of A.L.S. cases are inherited. The rest are sporadic, arising without warning in patients even though they do not have these mutations. “The holy grail of the field has been to find a point of molecular convergence” that might explain all types of A.L.S., Dr. Siddique said. The significance of the new report is that he and his team described a cellular problem that appears in both inherited and noninherited forms of the disease. In families with inherited A.L.S., the researchers discovered mutations in a gene that produces a protein called ubiquilin 2. It normally helps cells dispose of and recycle other proteins that are misfolded, damaged or no longer needed. At the same time, Dr. Siddique and his colleagues reviewed autopsy tissue from several dozen patients without the mutations in the gene for ubiquilin 2. Remarkably, they found that in every case, ubiquilin 2 nonetheless had accumulated abnormally in spinal cord tissue. In patients with A.L.S. and dementia, the protein had accumulated in the brain, as well. “It was clear that this particular protein was misregulated, and its function was probably impaired,” not only in the cases with the genetic mutations but across the board, Dr. Siddique said. This finding suggests that researchers might discover a way to treat a broad range of A.L.S. patients by singling out ubiquilin 2 or the chemical pathway it is part of. But many daunting questions remain. What makes this housekeeping protein spontaneously misfold and accumulate in cases of noninherited A.L.S.? And how important, ultimately, is its aberrant behavior to the overall development or progression of the disease? At least one other protein is known to go awry in all noninherited and virtually all inherited forms of A.L.S., noted Dr. Raymond Roos, a neurologist at the University of Chicago. That protein, called TDP43, normally plays a role in splicing and regulating molecules of RNA, which are then used to create new proteins. “So is one of these defective proteins more important than the other in the development of A.L.S.? Are there five others that are important, as well?” Dr. Roos asked. “These are questions that still need to be answered.” The mysteries of A.L.S. mirror to some degree those of other neurodegenerative diseases, like Alzheimer’s. There, too, misfolded, accumulated proteins are hallmarks of the pathology — and sources of contention. Some researchers argue that aggregations of beta-amyloid proteins are the key culprits. Others focus on tau proteins, which also accumulate abnormally. Still others suggest that protein aggregates are markers, rather than root causes, of dysfunction. In A.L.S., “we can look at autopsy samples and see what’s happened in the end,” Dr. Lucie Bruijn of the A.L.S. Association said. “But in living people, it’s difficult to figure out what the beginning looks like.”

Locations of Motorneurons Affected by ALS
The anterior horn cells of the spinal cord are affected Death of LMNs leads to denervation, with subsequent shrinkage of musculature and muscle fiber atrophy. The UMNs of the cerebral cortex are affected later Lastly the motor nuclei of the brain stem, particularly the hypoglossal nuclei are affected Lou Gehrig

xv Steven Hawking

Spinal Cord Trauma Often leads to paraplegia or quadriplegia depending on the location and extent of the injury Hyperextension Injury When the forehead is struck and driven posteriorly Diving impact in shallow water May tear the anterior spinal ligament and spinal cord may contact the vertebral body

Trauma to the Spinal Cord
Hyperflexion Injury When the head of shoulders are struck from behind by an object of considerable weight or from a fall

Hyperextension injury

Spinal Cord Trauma Concussion Mild injury, transient and reversible
Contusion Severe trauma with hemorrhagic necrosis, edema and softening of the cord – Myelomalacia, or blood in the cord – Hematomyelia Laceration or Tansection

Cervical Contusion Cervical Contusion

Disorders Arising in the Basal Ganglia
Characteristics of Disorders of the Basal Ganglia Involuntary movements Alterations in muscle tone Disturbances in body posture

Characteristics of Disorders of the Basal Ganglia
Involuntary movements Alterations in muscle tone Disturbances in body posture

Types of Involuntary Movement Disorders
Tremor = Trembling or vibrating Tics = A habitual spasmodic contraction of the muscles, most often in the face Chorea = Irregular writhing movements Athetosis = Wormlike twisting of limb Ballismus = Violent flinging motion of limbs Dystonia = Abnormal posture Dyskinesias = Bizarre wriggling movements Tardive Dyskinesia Develops due to use of antipsychotic medications

Parkinson Disease Characteristics Clinical syndrome
0.3% of the general population has Parkinson Disease = 80,000 people Usually begins after 50 years of age Affects men twice as often as women Course of the disease is years Clinical syndrome Parkinsonism James Parkinson, 1817 = ‘shaky palsy’

Parkinson Disease Degeneration of pigmented neurons (containing dopamine) in the substantia nigra Cause unknown: May be environmental/genetic Early symptoms: tremor, rigidity, slow movement Later: cognitive problems, dementia, dyskinesia Gross: atrophy of substantia nigra Microscopic: Lewy bodies (inclusions in neurons)

Parkinson Disease Cogwheel-type motion Bradykinesia Difficulty walking
Ratchet-like movements Bradykinesia Slowness initiating and performing movements Difficulty walking Neuropsychiatric disorders

Parkinson disease (R) : atrophy of substantia nigra
xv Parkinson disease (R) : atrophy of substantia nigra

Parkinson disease: Lewy body
xv Parkinson disease: Lewy body

Michael J. Fox and Muhammad Ali
xv Michael J. Fox and Muhammad Ali

Huntington Disease Degeneration of basal ganglia and cerebral cortex
Early symptoms: lack of coordination, unsteady gait Later: chorea (involuntary writhing), psychiatric symptoms, dementia Autosomal dominant mutation on chromosome 4 Begins in 30s-40s; slow progression over years

Read this story about Katharine and her family:
xv Read this story about Katharine and her family:

Multiple Sclerosis (MS)
A Demyelinating Disease of the CNS Most common non-traumatic cause of neurologic disability among young and middle-aged adults Characterized by exacerbations and remissions over many years in several different sites in the CNS Initially, there is normal or near-normal neurologic function between exacerbations. As the disease progresses, there is less improvement between exacerbations and increasing neurologic dysfunction.

Multiple Sclerosis Most common demyelinating disorder
Etiology unknown; related to autoimmunity Variety of motor and sensory symptoms Relapsing-remitting course Plaques (areas of demyelination) in brain, cord

xv Multiple sclerosis

Multiple sclerosis plaques around ventricles
xv Multiple sclerosis plaques around ventricles

Segmental Demyelination
Disorder of the Schwann cells Guillain-Barré Syndrome Autoimmune disorder Linked to CMV, Campylobacter jejuni, and Epstein-Barr Virus Common in people of both sexes between ages 30 and 50 Can replace the Schwann cells New myelin sheath is thin and subject to injury A serious disorder that occurs when the body's defense (immune) system mistakenly attacks part of the nervous system. This leads to nerve inflammation that causes muscle weakness.

Guillain-Barre Syndrome
Acute peripheral neuropathy Progressive, ascending weakness Usually self-limited (but may involve respiratory muscles, requiring respiratory intensive care) Autoimmune attack on peripheral nerve resulting in demyelination and conduction block

Guillain-Barré Syndrome
Symptoms Rapidly progressing limb weakness and loss of tendon reflexes Flaccid paralysis Pain May lead to death due to ventilatory failure and autonomic disturbances Treatment Plasmapheresis Intravenous Immunoglobulin therapy 80-90% achieve a full and spontaneous recover in 6 to 12 months

Alzheimer Disease Most common cause of dementia in the elderly
Symptoms: Early on: forgetfulness, memory disturbances Language deficits, loss of learned motor skills, alterations in mood/behavior, disorientation Finally: patient becomes profoundly disabled, mute, immobile Gross: Cortical atrophy, neuronal loss Microscopic: neurofibrillary tangles, neurotic plaques

Alzheimer Disease http://www.youtube.com/watch?v=y3g4emLQ1Ic
Neurofibrillary tangles Cytoplasmic bundles of filaments encircling the nucleus of pyramidal cells Tau protein Amyloid beta protein Produced instead of an integral protein Triggers an inflammatory response Tau proteins are proteins that stabilize microtubules.They are abundant in neurons of the central nervous system and are less common elsewhere, but are also expressed at very low levels in CNS astrocytes and oligodendrocytes. Pathologies and dementias of the nervous system such as Alzheimer's disease can result when tau proteins become defective and no longer stabilize microtubules properly. The two hallmark pathologies required for a diagnosis of Alzheimer’s disease (AD) are the extracellular plaque deposits of the β-amyloid peptide (Aβ) and the flame-shaped neurofibrillary tangles of the microtubule binding protein tau.

Alzheimer disease: brain atrophy
xv Alzheimer disease: brain atrophy

Alzheimer disease: progression
xv Alzheimer disease: progression

Alzheimer disease: plaques and tangles
xv Alzheimer disease: plaques and tangles

Alzheimer disease: plaques (L) and tangles (R)
xv Alzheimer disease: plaques (L) and tangles (R)

Components of the Peripheral Nervous System
Motor and sensory branches of the cranial and spinal nerves The peripheral parts of the autonomic nervous system Peripheral ganglia Neuron cell bodies grouped together in the PNS

Disorders of Skeletal Muscle Groups
Muscular atrophy If a normally innervated muscle is not used for long periods, the muscle cells shrink in diameter, lose much of their contractile protein, and weaken. Muscular dystrophy Genetic disorders that produce progressive deterioration of skeletal muscles because of mixed muscle cell hypertrophy, atrophy, and necrosis

Muscular Dystrophy Involves the motor neuron
Probably do not involve the nervous system Slow progressive onset of muscle weakness

Duchenne Muscular Dystrophy
1:3500 male births Inherited recessive single-gene defect On short arm of X chromosome Gene codes for dystrophin Connects Z-lines to connective tissue surrounding muscle Break down of sarcolemma = necrosis of muscle fibers

Duchenne Muscular Dystrophy
Symptoms usually appear before age 6 and may appear as early as infancy. They may include: Fatigue, mental retardation, muscle weakness (begins in legs and pelvis), difficulty with motor skills (running, jumping hopping), frequent falls May be confined to wheelchair by age of 12

Signs and Tests A complete nervous system (neurological), heart, lung, and muscle exam may show: Abnormal heart muscle Congestive heart failure Arrhythmia Scoliosis Respiratory disorders Muscle wasting

Tests Electromyography (EMG) Genetic tests Muscle biopsy Serum CPK

Treatments There is no known cure for Duchenne muscular dystrophy.
Treatment aims to control symptoms to maximize quality of life. Gene therapy may become available in the future.

Becker Muscular Dystrophy
Very similar to Duchenne muscular dystrophy Becker muscular dystrophy gets worse much more slowly 3 - 6 out of every 100,000 males X-linked Manifests later in childhood of adolescence

Myasthenia Gravis Definition Cause
Disorder of transmission at the neuromuscular junction that affects communication between the motoneuron and the innervated muscle cell Cause Autoimmune disease caused by antibody-mediated loss of acetylcholine receptors in the neuromuscular junction Sensitized Helper T Cells Antibody directed attack on receptors

Myasthenia Gravis Muscle weakness and fatigability with sustained effort Ptosis due to eyelid weakness Diplopia Progresses to generalized weakness Myasthenic crisis Compromised ventilation Usually during a period of stress

Diagnosis Tensilon or Edrophonium test MUSK antibodies
Acetylcholinesterase inhibitor Patient feels little to no weakness for a short period of time MUSK antibodies

Treatment Plasmapheresis Intravenous immunoglobulin
Pyridostigmine and neostigmine are the drugs of choice Drug used to inhibit acetylcholinesterase Plasmapheresis Removes antibodies from circulation Intravenous immunoglobulin Unknown how it works

Causes of Polyneuropathies
Immune mechanisms (Guillain-Barré syndrome, rheumatoid arthitis, lupus, hypothyroid) Toxic agents (arsenic polyneuropathy, lead polyneuropathy, alcoholic polyneuropathy) Metabolic diseases (diabetes mellitus, uremia, chronic kidney disease) Low levels of vitamin B12 or other problems with your diet Poor blood flow to the area

Alterations of Neuromuscular Function
Drugs and Toxins can alter neuromuscular function by changing the release, inactivation, or receptor binding of acetylcholine. Curare acts on the post-junctional membrane of the motor endplate to prevent the depolarizing effect of the neurotransmitter. Used during many types of surgical procedures Clostridium botulinum blocks acetylcholine release and results in paralysis Botox Organophosphates block acetylcholinesterase Nerve gases and pesticides

THE END

Nerve Root Injuries Herniated or Ruptured intervertebral disk
Sensory deficits Spinal nerve root compression Paresthesias and numbness Particularly of the leg and foot Knee and ankle reflexes also may be diminished or absent Motor weakness and Pain

Question Lead toxicity would result in which of the following conditions? Mononeuropathies Polyneuropathies Upper motor lesion Myasthenia gravis

Answer Mononeuropathies
Polyneuropathies: Polyneuropathies would result from systemic exposure to lead. Upper motor lesion Myasthenia gravis

Spinal Cord Injury (SCI)
Definition Damage to the neural elements of the spinal cord Causes Motor vehicle crashes, falls, violence, and sporting activities Involvement Most SCIs involve damage to the vertebral column and/or supporting ligaments as well as the spinal cord. Commonly involve both sensory and motor function

Types of Injuries to the Vertebral Column
Fractures Dislocations Subluxations

Types of Incomplete Spinal Cord Injuries
Central cord syndrome Anterior cord syndrome Brown-Séquard syndrome Conus medullaris syndrome

Areas Affected by SCI Spinal reflexes Ventilation and communication
Autonomic nervous system Temperature regulation Edema and deep vein thrombosis Sensorimotor function

Areas Affected by SCI (cont.)
Skin integrity Pain reception Bladder and bowel function Sexual function

Question Demyelination is the causative factor in which disease?
Parkinson disease ALS Multiple sclerosis

Answer Parkinson’s disease ALS
Multiple sclerosis: MS is caused by an autoimmune attack on the oligodendrocytes (and Schwann cells in the peripheral nervous system) of the CNS.

Classifications of Muscles
Extensors Muscles that increase the angle of a joint Flexors Muscles that decrease the angle of a joint

Components of the Neuromuscular System
Neuromuscular unit containing motor neurons Myoneural junction Muscle fibers Actin and Myosin Spinal cord Efferent pathways from the brain stem circuits

Requirements of Motor Systems
Upper motoneurons project from the motor cortex to the brain stem or spinal cord. Directly or indirectly innervate the lower motoneurons or contracting muscles Motor unit is a motor neuron and all the muscle fibers it innervates Sensory feedback from the involved muscles Continuously relayed to the cerebellum basal ganglia and sensory cortex Functioning neuromuscular junction that links nervous system activity with muscle contraction

Mechanisms Controlling Coordinated Movement
Agonists Promote movement Antagonists Oppose movement Synergists Assist the agonist muscles by stabilizing a joint or contributing additional force to the movement

Motor Unit The motor neuron and the muscle fibers it innervates
A single motor neuron may innervate a few thousand muscle fibers Upper motor neurons Lower motor neurons

Upper motoneuron (UMN’s) Originate in the motor region of the cerebral cortex or brain stem Carries motor information down spinal cord to stimulate target muscle Lesions can involve the motor cortex, the internal capsule, or other brain structures through which the corticospinal or corticobulbar tracts descend, or the spinal cord

2. Babinski sign is present:
1. Paralysis or weakness of movements of the affected side but gross movements may be produced. No muscle atrophy is seen initially 2. Babinski sign is present: 3. Loss of performance of fine-skilled voluntary movements especially at the distal end of the limbs 4. Superficial abdominal reflexes and cremasteric reflex are absent. 5. Spasticity or hypertonicity of the muscles. 6. Clasp-knife reaction: initial higher resistance to movement is followed by a lesser resistance 7. Exaggerated deep tendon reflexes and clonus may be

Lower motoneurons (LMN’s) Connects the brainstem and spinal cord to muscle cells Brings nerve impulses from upper motor neuron to the muscles Lesions disrupt communication between the muscle and all neural input from spinal cord reflexes, including the stretch reflex, which maintains muscle tone

Signs of Lower Motor Neuron Lesions (LMNL)
1. Flaccid paralysis of muscles supplied. 2. Atrophy of muscles supplied. 3. Loss of reflexes of muscles supplied. 4. Muscles fasciculation (contraction of a group of fibers) due to irritation of the motor neurons – seen with naked eye

Cerebellum-associated movement disorders
Causes Congenital defect, vascular accident, or growing tumor Types Vestibulocerebellar ataxia Not smooth movement Decomposition of movement Cerebellar tremor Rhythmic back-and-forth movement of a finger or toe Cannot maintain a fix on the body part

Spinal Cord Dorsal column-medial lemniscus tract
Touch/proprioception/vibration sensory pathway Anterolateral system Pain/temperature sensory pathway

Spinal Cord Corticospinal tract
Motor pathway for upper motor neuronal signals coming from cerebral cortex and brainstem motor nuclei

Peripheral Nerve Regeneration
Damage to a peripheral nerve axon due to injury or neuropathy Results in degenerative changes, followed by breakdown of the myelin sheath and Schwann cells Regeneration factors Proximity to soma Crushing vs. cutting

Peripheral Neuropathy
Definition Any primary disorder of the peripheral nerves Results Muscle weakness, with or without atrophy and sensory changes Involvement Can involve a single nerve (mononeuropathy) or multiple nerves (polyneuropathy)

Mononeuropathies Caused by localized conditions such as trauma, compression, or infections that affect a single spinal nerve, plexus, or peripheral nerve trunk Fractured bones may lacerate or compress nerves. Excessively tight tourniquets may injure nerves directly or produce ischemic injury. Infections such as herpes zoster may affect a single segmental afferent nerve distribution.

Mononeuropathies Carpal Tunnel Syndrome
Compression-type mononeuropathy Median nerve compression Tinsel Sign Development of a tingling sensation in palm by light percussion on median nerve at the wrist

Polyneuropathy Involves demyelination or axonal degeneration of multiple peripheral nerves that leads to symmetric sensory, motor, or mixed sensorimotor deficits Typically, the longest axons are involved first, with symptoms beginning in the distal part of the extremities.

Question Which motor system is responsible for crude muscle movements?
Pyramidal motor system Extrapyramidal motor system

Answer b. Extrapyramidal motor system: This system originates in the basal ganglia and provides background for the more crude, supportive movement patterns.

Disorders of Motor Function

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