Neurological Pathophysiology

What ion is usually in control of neural impulses?

Calcium

Electrical Synapse

Gap junctions, seen in cardiac nodal cells

Chemical Synapse

Neurotransmitters send signal to next neuron

Excitatory Neurotransmitters

Make post-synaptic cell more positive, depolarizes cell

Inhibitory Neurotransmitters

Make post-synaptic cell more negative, hyperpolarizes cell

Regional Distribution of Nerves

Helps diagnose the cause of coal neurological sxs

Seizure

Sudden disruption of brain electrical activity caused by abnormally excessive cortical neuron activity

Seizure Locations

Can be focal or generalized throughout the entire cerebral cortex

What causes seizures?

Often a manifestation of underlying clinical disease

Pathogenesis of Seizures

Overactive glutamate (excitatory neurotransmitter) or underactive GABA (inhibitory neurotransmitter) alter neural excitability

Tonic Focal Seizure

Stiffening of muscles, frontal lobe

Clonic Focal Seizure

Rhythmic twitching, frontal lobe

Atonic Focal Seizure

Loss of muscle tone, frontal lobe

Parietal/Temporal/Occipital Focal Seizure

Loss of senses processed in the area of the seizure

Generalized Seizure

Bilateral symptoms, usually tonic-clonic, autonomic dysfunction, impairment

Generalized Seizure Autonomic Dysfunction

Incontinence, hypertension, tachycardia

Generalized Seizure Impairment

Involvement of thalamus and reticular formation, loss of consciousness, post-ictal confusion and amnesia

How long does a seizure usually last?

1-2 minutes, brain spontaneously aborts due to endogenous processes

Cerebral Vascular Accidents (CVA's)

Loss of blood flow to the brain, hypoxic cellular injury, can b eischemic or hemorrhagic

CVA Result

Permanent damage to neurons and loss of function

Ischemic Stroke

Lack of blood flow to brain tissue, embolic, thrombotic, hemodynamic

Embolic Stroke Causes

Cardiac emboli, arterial emboli, paradoxical emboli

Thrombotic Stroke Causes

ATHEROSCLEROSIS, commonly occurs in carotids, vertebral arteries, small vessels deep in brain (lacunar infarcts)

Hemodynamic Stroke

Hypoperfusion of vulnerable areas of the brain (furthest from blood vessels), caused by anything that result sin significant hypotension

Ischemic Stroke Pathophysiology

No oxygen reaching cells, cell swelling and death, inflammatory response, cerebral edema, increased ICP

Hemorrhagic Stroke Causes

Ruptured cerebral blood vessels, trauma or HTN (weakens walls of vessels, aneurysm formation)

Hemorrhagic Stroke Pathophysiology

Rupture of vessel, blood pools in brain, hematoma compresses brain tissue, ischemic injury and increased ICP

OR

Decreased downstream perfusion, ischemic injury, inflammatory response, cerebral edema, increased ICP