Veterinary Neurology

Adventures in the Nervous System

What Makes the Nervous System Unique?

Contains neurons Connects to and

influences all parts of the body

Electrically active and sends information great distances

The ethereal brain

Cells of the Nervous System

Neurons Astrocytes

Oligodendroglial or Schwann cells Microglia

Cells of the Nervous System

Neurons Astrocytes

Oligodendroglial or Schwann cells Microglia

Cells of the Nervous System

Neurons Astrocytes

Oligodendroglial or Schwann cells Microglia

Cells of the Nervous System

Neurons Astrocytes

Oligodendroglial or Schwann cells Microglia

Types of Neurons

Bipolar• Special sensory

neurons Pseudounipolar

• Dorsal root ganglion cells

Multipolar• Most neurons

Types of Neurons

Bipolar• Special sensory

neurons Pseudounipolar

• Dorsal root ganglion cells

Multipolar• Most neurons

Function of Glial Cells

Oligodendroglial and Schwann cells• Nurture neurons

Astrocytes• Support• Blood-Brain barrier

Microglia• Immune function

(phagocytosis)

Anatomy of the Action Potential

-70 mV resting membrane potential• maintained by

semipermeable membrane and Na-K pump

Ion selective pores Spatial and

temporal process

Information Processing (neurotransmission)

Cerebral Blood Flow

Brain equals 2% of BW Brain receives 15% of

cardiac output• gray matter 3 time > white

matter Brain uses 20% of body’s

O2• 50% in young animals (< 2

mo.)• No O2 reserve

– loss of consciousness in 10 seconds

– irreversible damage in 3-5 minutes

CNS Energy Metabolism

CNS are entirely dependent upon O2 and glucose for energy

Production of ATP necessary to maintain the ion pump

Studying uses minimal energy

CSF Circulation

66% Formed in the Lateral, Third & Forth Ventricles

CSF Circulation

Flows from the Lateral Ventricle into the Third Ventricle through the Foramen of Monro

CSF Circulation

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

CSF Circulation

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

CSF Circulation

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

CSF Circulation

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

CSF Function

Shock absorption

Waste sink Chemical

message system

Divisions of the Nervous System

Cerebrum Brainstem

• Diencephalon• Mesencephalon• Metencephalon• Myelencephalon

Cerebellum Spinal Cord Peripheral (and cranial)

nerves

Information to Assess a Neurologic Patient

History Physical

Examination Neurologic

Examination Minimum Data Base Ancillary Tests

Neurologic History

Signalment• Age• Species• Breed• Gender• Color

Neurologic History

Primary Complaint

Onset, Duration and Progression• Acute Non-

progressive• Acute Progressive• Chronic Progressive

Symmetry

Neurologic History

Specific Questions• Vaccination

Status• Travel History• Toxin Exposure• History of

Trauma• Previous

Therapy• Other illness

Neurologic Assessment

Is it a neurologic disease?• Seizures• Intention tremor• CN deficits

– Head tilt– Nystagmus

• CP deficits• Dysmetria• Paralysis

Mechanisms of Disease

Degenerative Anomalous Metabolic Neoplastic/Nutritional Inflammatory/Infectious/Idiopathic/

Immune Mediated Traumatic/Toxic Vascular

Degenerative Disease

Chronic and Progressive diseases

Most common in older animals

Can affect the nervous system directly or indirectly

Anomalous Disease (Congenital)

Purebred animal

Young (or age specific)

Progressive (may have acute onset)

Symmetric or Asymmetric (most common)

Anomalous Disease

MRI transverse MRI saggital

Metabolic Disease

Young & Old Progressive Symmetrical Most common is

liver disease and hypoglycemia

Nutritional Disease

Most common in young or sick animals (chronically)

Progressive Usually,

symmetricalBrainstem hemorrhages secondary to thiamine deficiency.

Neoplastic Disease

Old and Young More common than

at any time in the past

Improved diagnostics like MRI

Surgery and 3-D Radiosurgery

Progressive & Asymmetrical

Infectious/Inflammatory

Caused by infectious organisms (Young & Old)

Immune-mediated disease (Middle Age)

Affect CNS directly or indirectly

Progressive & Asymmetrical

CSF cytology form a dog exhibitinga mixed reaction with neutrophils,lymphocytes and macrophages.

Idiopathic Syndromes

Specific neurologic syndromes

Many are immune medicated

Affect any part of the nervous system, but particularly the cranial nerves and pns

Middle Age

Traumatic Disease

Acute Non-

progressive unless unstable

Usually, asymmetrical

Require immediate intervention

Any Age

Toxic Disease

Young & Old Progressive Symmetrical Plants, Pesticides

(organophosphates), Heavy metals (lead), and Household chemicals

Vascular Disease

Acute Non-

progressive Minimize the

collateral damage with anti-oxidants

Can improve dramatically in 3-5 days

Any Age