Seizure Pathophysiology

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.)

Altered permeability of

Reduced inhibitory for

Neurotransmitter

neuronal membrane

control of neurons

imbalance

Lower threshold for stimulation

Hyperexcitable epileptogenic focus

Sudden, spontaneous, uncontrolled depolarization of neurons

Depolarization spreads through focal cells stimulating the surrounding cells via cortical synapses

SEIZURE PATHOPHYSIOLOGY

Depolarization spreads through intrahemospheric tracts to contralateral cortex, basal ganglia, thalamus and brainstem

Spread of depolarization

Inhibitory neurons in

Increased cerebral blood flow,

to the spinal cord

cortex, anterior

Increased oxygen and glucose

thalamus and basal

consumption

ganglia begin to inhibit Abnormal motor or

cortical excitation

sensory activity

Cerebral

Cerebral

hypoxia

hypoglycemia

Metabolic

SIGNS AND SYMPTOMS

acidosis

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

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.