Pathophysiology - Seizure Disorders

Seizure Disorders – a sudden alteration in normal brain activity that causes distinct changes in behaviour and body function.

CLASSIFICATION

1. Partial or focal seizures – originate in localized area of the cortex
2. Simple partial seizures – do not affect consciousness and may have motor, sensory, autonomic symptoms
3. Complex partial seizures – includes alteration in consciousness coupled with automatisms (e.g. lip smacking, chewing, aimless walking)
4. Generalized seizures – involve diffuse regions of the brain in a bilaterally symmetric fashion
5. Tonic-clonic seizures (grand mal) – cause sudden loss of consciousness, loss of postural control, tonic muscular contractions producing teeth clenching and rigidity in extension (tonic phase) followed by rhythmic muscular jerking (clonic phase)
•  tongue biting and incontinence may occur during the seizure
•  phases – pre ictal, aura, post ictal
6. Absence seizure (petit mal) – there is sudden, brief impairment of unconsciousness without loss of postural control events rarely last longer  than 5-10 seconds but can recur many times per day

CAUSES

• May be unknown or;
• Trauma to head or brain
• Cranial surgery
• Metabolic disorders (hypocalcemia, hyponatremia, hypogycemia, hyperglycemia, anoxia)
• Drug toxicity such as theophylline, lidocaine
• Central Nervous System infections
• Drug withdrawal states ( alcohol, barbiturates)

CLINICAL MANIFESTIONS

• Impaired consciousness
• Disturbed muscle tone or movement
• Disturbances of behaviour, mood, sensation or perception
• Disturbances of autonomic function

DIAGNOSTIC EVALUATION

• ECG – locates epileptic focus; helps classify seizure type
• Physical and Neuro exams – to determine the type, frequency and severity of seizures
• Biochemical, hematologic and serotologic tests
• MRI, CT – to identify lesions, local abnormalities, cerebral vascular abnormalities and cerebral degenerative changes that may be the cause of seizure

MANAGEMENT

• Pharmacologic treatment
•  diazepam, lorazepam IV – to halt seizures
• GA with a short acting barniturate – may be used if initial treatment is unsuccessful
• Carbamazepine, phynetoin, phenobarbital, ethosuximide – to help maintain a seizure free state
• Surgical procedures
• Temporary lobectomy
• Corpus callostomy
• Hemispherectomy
• Vagal nerve stimulation

NURSING MANAGEMENT

1. Maintaining cerebral tissue perfusion

• Maintaining a patent airway until patient is fully awake after a seizure
• Provide oxygen during a seizure if color change occurs
• Stress the importance of taking medications regularly
• Monitor serum therapeutic range of medications
• Monitor patient for toxic side of medications
• Monitor platelet and liver functions for toxicity due to medications to prevent injury

2. Preventing injury

• Provide a safe environment by padding side rails
• Place the bed in a low position
• Do not restrain patient during seizure attacks
• Place the patient on his side during a seizure to prevent aspiration
• Protect the patient’s head during a seizure