Neuromuscular Disorders Guillain-Barré Syndrome - Chapter 30 Myasthenia Gravis – Chapter 31

Neuromuscular Diseases Guillain-Barré Syndrome Myasthenia Gravis Amyotrophic Lateral Sclerosis (ALS) Muscular Dystrophy Multiple Sclerosis Cerebral Palsy Spinal cord injury

Guillain-Barré Syndrome

Definition An acute, usually rapidly progressive form of inflammatory polyneuropathy characterized by muscular weakness and mild distal sensory loss, which in about 2/3 of cases, begins 5 days to 3 weeks after a banal infectious disorder, surgery, or an immunization. Disorder of the peripheral nervous system. Also known as Landry's Ascending Paralysis Acute Inflammatory Demyelinating Polyradiculoneuropathy Post-infectious polyneuritis Acute post-infection polyneuropathy

Etiology Cause is unknown. Autoimmune? Follows a febrile infection by 1-4 weeks: Upper Respiratory Tract GI illness Viruses and bacteria Infectious mononucleosis is associated with 25% of cases. Followed the swine flu influenza vaccination in cases of Guillain-Barré and 25 deaths.

Etiology Parainfluenza 2 Variola Measles Mumps Hepatitis A and B Mycoplasma Pneumoniae Salmonella typhi

Etiology All age groups Greater incidence in age group > 45 years age. Either sex Greater incidence in males. Greater incident in white population. No seasonal clustering.

Pathophysiology Most common acquired demyelinating neuropathy. Inflammation and deterioration of peripheral nervous system. Decreased ability of the neurons to transmit impulses to the muscles. Paralysis.

Neurilemma The outer membrane of the Schwann cells is called the neurilemma. Neurilemma is essential for regeneration of cut and injured axons. Axons in the brain and spinal cord have no neurilemma and therefore cannot regenerate.

Clinical Manifestations Progressive ascending skeletal muscle paralysis. Ground to brain (G-B). Tingling sensation and numbness. Paresthesia Loss of deep tendon reflexes. Sensory nerve impairment. Peripheral facial weakness. Decreased gag reflex. Decreased ability to swallow. Dysphagia

Symptoms Fever Malaise Nausea prostration. Tingling or numbness in extremities. Feet/legs affected first. Paralysis and loss of reflexes.

Ventilatory Failure Mucous Accumulation Airway Obstruction Alveolar Consolidation Atelectasis

Progression of the Disease Paralysis peaks in less than 10 days. Progression of the paralysis may stop at any point. As paralysis reaches its maximum, it usually remains unchanged for a few days to weeks.

Clinical Manifestations ABG Acute ventilatory failure with hypoxemia. Cyanosis PFT Restrictive lung disease. Decreased volumes. Breath Sounds decreased.

Diagnosis Neurological symptoms. Cerebral Spinal Fluid. Increased protein and normal cell count. Electro-diagnostic studies.

X-ray Normal. If atelectasis is present: Radiopaque or radiodense (white).

Autonomic Nervous System Dysfunction Develops in 50% of cases Sympathetic Parasympathetic Loss of bowel and bladder sphincter control may occur

Management Oxygen Frequent monitoring of pulmonary function parameters. Vital capacity NIF or MIP & MEP Frequent monitoring of PO and ABG. Mechanical ventilation: Ventilatory Respiratory Failure. Tracheostomy

Management Hyperinflation Protocol. Bronchial Hygiene Protocol. Risk of thromboembolic events: Subcutaneous heparin. Elastic stockings. Passive range of motion exercises. Management of bedsores: Frequent turning. Monitor for Pneumonia (infection).

Management Urinary catheterization. Treat cardiac dysrhythmias. Plasmapheresis Withdraw blood. Separate out the plasma & discard. Re-infuse the cells with fresh frozen plasma. Decreases the antibodies. Total of five exchanges of 3 L each over 8-10 days. Steroid Therapy is controversial.

Pulmonary Function Monitoring Mechanical Ventilation is indicated if: If VC decreases to cc/kg or less. NIF (MIP) is –20 cm H20 or lower. f increases above 30/min.

Prognosis Spontaneous recovery is expected in % of cases. Improvement may take weeks or months. 30% of adults have residual weakness at 3 years.

Myasthenia Gravis

Definition A disease characterized by episodic muscle weakness caused by loss or dysfunction of acetylcholine receptors. Chronic disorder. Axon and receptor site of the voluntary muscle. Periods of fatigue with improvement following rest.

Etiology Circulating anti-ACh receptor antibodies disrupt the chemical transmission of ACh. Blocking the ACh from the receptor site. Accelerating the breakdown of ACh. Destroying the receptor sites. Thymus gland is abnormal: Antibodies thought to come from the thymus gland.

Etiology Twice as common in women. Peak age of onset for females is 15 to 35 years. Peak age of onset for males is 40 to 70 yrs. Signs/symptoms are provoked by: Emotional upset. Physical stress. Exposure to extreme temperature changes. Febrile illness. Pregnancy. Death is possible but incidence of deaths decline after 10 years.

Anatomic Alterations Isolated groups of muscles (eyelids). Generalized muscle weakness: May include the diaphragm. Ventilatory Failure.

Clinical Findings Weakness of striated muscle Eye muscles (ptosis). Extraocular muscles (diplopia). Muscles of the lower portion of the face (speech impairment). Chewing and swallowing muscles (dysphagia). Muscles of the arms and legs.

Clinical Findings Descending paralysis. Mind to Ground (MG) Gradual onset. First symptoms. Drooping of the eyelids. If only the eyes are involved than it is referred to as Ocular Myasthenia.

Clinical Findings Generalized skeletal muscle disorder Muscles of neck and face. Unable to chew and swallow. Aspiration Unable to speak clearly. Weakness of neck muscles causes the patients head to fall forward.

Clinical Findings Weakness of arms and legs results in difficulty in: Climbing stairs. Lifting objects. Maintaining balance. Walking. Hand cannot lift to the mouth.

Clinical Findings Pain is rare. Tendon reflexes remain intact. Patient may demonstrate normal health for weeks and months at a time. May only show signs of weakness late in the day or at night (exhaustion). Develop a sudden and transient generalized muscle weakness that includes the diaphragm.

Clinical Findings If ventilatory failure is handled properly the chest x-ray findings should be normal. If improperly managed: Alveolar consolidation Atelectasis Excessive secretions

ABG Acute ventilatory failure with hypoxemia Decreased pH Increased PaCO 2, Decreased PaO 2 Hypoxemia secondary to hypoventilation

Clinical Findings Pulmonary Functions Decreased volumes. Cyanosis Diminished BS X-ray Normal or radiopaque (white) if atelectasis is present.

Diagnosis Clinical history. Clinical response to an IV injection of edrophonium chloride (Tensilon). Tensilon Test Tensilon is an anticholinesterase. Electrophysiological tests (EMG). Circulating antibody levels in the blood. Enlarged Thymus gland.

Thymus Gland Manufacture T- lymphocytes.

Management Patients may live a normal life span. Exacerbation: Oxygen Frequent monitoring of VC and NIF. Frequent monitoring of BP and SpO 2. Frequent monitoring of ABG. Mechanical ventilation.

Management of MG Anticholinesterase Drugs Edrophonium Chloride (Tensilon) Neostigmine (Prostigmine) Pyridostigmine (Mestinon) Steroid Therapy Prednisone ACTH therapy

Management of MG Thymectomy Useful in young adult females Plasmapheresis Bronchial hygiene Hyperinflation protocol Atelectasis

Myasthenia Crisis vs. Cholinergic Crisis Myasthenia Crisis Exacerbation of the disease. Muscle strength improves after Tensilon Test. Increase dosage of anticholinesterase agents. Cholinergic Crisis Too much anticholinesterase drugs. No muscle strength noted after Tensilon. Stop or decrease dosage of anticholinesterase agents and give atropine. MEDICAL EMERGENCY

SPINAL CORD INJURY

Spinal Nerves 31 Pair 8 Cervical 12 Thoracic 5 Lumbar 5 Sacrospinal 1 Coccygeal

Spinal Cord Injury High neck fractures (above C3). Apnea. All respiratory muscles are affected. Mechanical ventilation/Tracheostomy. Injury to C3-C8 is a quadriplegic but retains some use of respiratory muscles. Night-time mechanical ventilation. Injury below C8. Cough weak and ineffective secretion removal. Loss of function of abdominal muscles.

Amyotrophic Lateral Sclerosis

Lou Gehrig’s Disease Anterior Horn Cells. Weakness of hands and less often in the feet. The site of onset is random, and progression is asymmetric. Dysarthria and dysphagia are due to involvement of brain stem nuclei and pathways. Sensory systems, voluntary eye movements, and urinary sphincters are spared. Rarely, a patient survives 30 years 50% die within 3 years of onset. 20% live 5 years. 10% live 10 years.

ALS can strike anyone. Male or female Any ethnic origin At any age Some have been diagnosed as teens Usual onset is in middle age