SEIZURE PATHOPHYSIOLOGY

Etiology: -Idiopathic -Familial incidence -Physical stimuli (head trauma, loud noises or bright lights) -Biochemical stimuli (stress, CNS infection, brain tumor, high fever, hypertension, metabolic and toxic conditions, drug and alcohol withdrawal, excessive premenstrual fluid retention, etc.)

Lower threshold for

stimulation

Sudden, spontaneous, uncontrolled

depolarization of neurons

Hyperexcitable

epileptogenic focus

Reduced inhibitory for

control of neurons

Neurotransmitter

imbalance

Altered permeability of

neuronal membrane

Depolarization spreads through focal

cells stimulating the surrounding

cells via cortical synapses

SEIZURE PATHOPHYSIOLOGY

Abnormal motor or

sensory activity

SIGNS AND SYMPTOMS TONIC PHASE: -loss of consciousness -muscle contraction and brief flexion -extension of limbs and rigid trunk -abdominal and thoracic muscle contract forcing air out of the lungs, then jaws are clenched tightly and respiration ceases -AUTONOMIC SYMPTOMS: increase blood pressure, heart rate and bladder pressure, flushing, sweating, increased salivation and bronchial secretion, and apnea CLONIC PHASE: -Alternate muscle contraction and relaxation -forceful rhythmic jerky movements -increased salivation -biting of tongue, cheek or lip -bowel and bladder incontinence POST-ICTAL PHASE: -confusion, fatigue, aching muscle -may fall into deep sleep

Seizure

Depolarization spreads through

intrahemospheric tracts to

contralateral cortex, basal ganglia,

thalamus and brainstem

Spread of depolarization

to the spinal cord

Inhibitory neurons in

cortex, anterior

thalamus and basal

ganglia begin to inhibit

cortical excitation

Increased cerebral blood flow,

Increased oxygen and glucose

consumption

Cerebral

hypoxia

Cerebral

hypoglycemia

Metabolic

acidosis

Status Epilepticus

Complications: -severe hypoxia -hypoglycemia -acidosis -injury

Brain damage and mental retardation

Reference: Gould, B. E. (2007). Pathophysiology for the health professions. Elsevier Singapore PTE LTD. Smeltzer, S. C., Brenda, B. G., Hinkle, J. L., & Cheever, K. H. (2008). Brunner & suddarth's textbook of medical-surgical nursing. Philadephia: Lippincott Williams & Wilkins.