Veterinary Neurology Adventures in the Nervous System

What Makes the Nervous System Unique? b Contains neurons b Connects to and influences all parts of the body b Electrically active and sends information great distances b The ethereal brain

Cells of the Nervous System b Neurons b Astrocytes b Oligodendroglial or Schwann cells b Microglia

Cells of the Nervous System b Neurons b Astrocytes b Oligodendroglial or Schwann cells b Microglia

Cells of the Nervous System b Neurons b Astrocytes b Oligodendroglial or Schwann cells b Microglia

Cells of the Nervous System b Neurons b Astrocytes b Oligodendroglial or Schwann cells b Microglia

Types of Neurons b Bipolar Special sensory neurons b Pseudounipolar Dorsal root ganglion cells b Multipolar Most neurons

Types of Neurons b Bipolar Special sensory neurons b Pseudounipolar Dorsal root ganglion cells b Multipolar Most neurons

Function of Glial Cells b Oligodendroglial and Schwann cells Nurture neurons b Astrocytes Support Blood-Brain barrier b Microglia Immune function (phagocytosis)

Anatomy of the Action Potential b -70 mV resting membrane potential maintained by semipermeable membrane and Na-K pump b Ion selective pores b Spatial and temporal process

Information Processing (neurotransmission)

Cerebral Blood Flow b Brain equals 2% of BW b Brain receives 15% of cardiac output gray matter 3 time > white matter b Brain uses 20% of body’s O 2 50% in young animals (< 2 mo.) No O 2 reserve –loss of consciousness in 10 seconds –irreversible damage in 3-5 minutes

CNS Energy Metabolism b CNS are entirely dependent upon O 2 and glucose for energy b Production of ATP necessary to maintain the ion pump b Studying uses minimal energy

CSF Circulation b 66% Formed in the Lateral, Third & Forth Ventricles

CSF Circulation b Flows from the Lateral Ventricle into the Third Ventricle through the Foramen of Monro

CSF Circulation b Circulates around the Intrathalamic Adhesion and enters the Forth Ventricle via the Cerebral Aqueduct

CSF Circulation b Passes down the Central Canal of the Spinal Cord and leaves the Ventricular System via the Forman of Luschka

CSF Circulation b Passes cranially around the Brain and caudally down the Spinal Column in the Sub Arachnoid Space

CSF Circulation b Absorbed via the arachnoid granulations in the venous sinuses and at the spaces formed where nerves exit the CNS

CSF Function b Shock absorption b Waste sink b Chemical message system

Divisions of the Nervous System b Cerebrum b Brainstem Diencephalon Mesencephalon Metencephalon Myelencephalon b Cerebellum b Spinal Cord b Peripheral (and cranial) nerves

Information to Assess a Neurologic Patient b History b Physical Examination b Neurologic Examination b Minimum Data Base b Ancillary Tests

Neurologic History b Signalment Age Species Breed Gender Color

Neurologic History b Primary Complaint b Onset, Duration and Progression Acute Non-progressive Acute Progressive Chronic Progressive b Symmetry

Neurologic History b Specific Questions Vaccination Status Travel History Toxin Exposure History of Trauma Previous Therapy Other illness

Neurologic Assessment b Is it a neurologic disease? Seizures Intention tremor CN deficits –Head tilt –Nystagmus CP deficits Dysmetria Paralysis

Mechanisms of Disease b Degenerative b Anomalous b Metabolic b Neoplastic/Nutritional b Inflammatory/Infectious/Idiopathic/ Immune Mediated b Traumatic/Toxic b Vascular

Degenerative Disease b Chronic and Progressive diseases b Most common in older animals b Can affect the nervous system directly or indirectly

Anomalous Disease (Congenital) b Purebred animal b Young (or age specific) b Progressive (may have acute onset) b Symmetric or Asymmetric (most common)

Anomalous Disease MRI transverseMRI saggital

Metabolic Disease b Young & Old b Progressive b Symmetrical b Most common is liver disease and hypoglycemia

Nutritional Disease b Most common in young or sick animals (chronically) b Progressive b Usually, symmetrical Brainstem hemorrhages secondary to thiamine deficiency.

Neoplastic Disease b Old and Young b More common than at any time in the past b Improved diagnostics like MRI b Surgery and 3-D Radiosurgery b Progressive & Asymmetrical

Infectious/Inflammatory b Caused by infectious organisms (Young & Old) b Immune-mediated disease (Middle Age) b Affect CNS directly or indirectly b Progressive & Asymmetrical CSF cytology form a dog exhibiting a mixed reaction with neutrophils, lymphocytes and macrophages.

Idiopathic Syndromes b Specific neurologic syndromes b Many are immune medicated b Affect any part of the nervous system, but particularly the cranial nerves and pns b Middle Age

Traumatic Disease b Acute b Non-progressive unless unstable b Usually, asymmetrical b Require immediate intervention b Any Age

Toxic Disease b Young & Old b Progressive b Symmetrical b Plants, Pesticides (organophosphates), Heavy metals (lead), and Household chemicals

Vascular Disease b Acute b Non-progressive b Minimize the collateral damage with anti-oxidants b Can improve dramatically in 3- 5 days b Any Age