veterinary neurology adventures in the nervous system
TRANSCRIPT
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