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.
