Module 8.2 - Seizure Disorders Flashcards
What is a seizure?
It is a sudden, transient disruption in brain electrical function caused by abnormal excessive discharged of cortical neurons.
What is epilepsy?
It is a disease of the brain with:
- At least 2 unprovoked seizures occurring more than 24 hours apart, or
- One unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after 2 unprovoked seizures, occurring over the next 10 years, or
- Diagnosis of an epilepsy syndrome
What are convulsions?
It is a term often applied to seizures and refers to the tonic-clonic movement associated with some seizures.
What are some causes of seizures?
- Cause may be unknown
- Metabolic disorders:
- Acidosis
- Electrolyte imbalance (hyponatremia, hypocalcemia)
- Hypoglycemia
- Hypoxia
- Alcohol or barbiturate withdrawal are the MOST common cause of new onset seizures in adults
- CNS infection
- Head trauma
- Tumors or other space occupying lesions
- Vascular disease- MOST common cause of seizure disorder at age 60 or older
- Degenerative disorders- such as Alzheimer’s disease
- The MOST common cause of seizures is NONCOMPLIANCE with a drug regimen on the part of the patient in whom epilepsy has been diagnosed.
What are focal seizures?
Seizures originating in one (1) area of the brain; an aura is common
What are generalized seizures?
Seizures originating in BOTH sides of the brain simultaneously
What is status epilepticus?
It is a continuing or recurring seizure activity in which recovery from seizure activity is incomplete; unrelenting seizure activity can last 30 minutes or more; other forms can evolve into status epilepticus; medical emergency that requires immediate attention
How do seizures occur? (describe the pathophysiology behind them)
- A group of neurons may exhibit a paroxysmal depolarization shift and function as an epileptogenic focus.
- These neurons are hyper-excitable. Epileptogenic neurons fire more frequently and with greater amplitude. When the intensity reaches a threshold point, cortical excitation spreads to the tonic phase (muscle contraction with increased muscle tone) and is associated with loss of consciousness.
- The clonic phase (alternating contraction and relaxation of muscles) begins when inhibitory neurons in the cortex, anterior thalamus and basal ganglia react to the cortical excitation.
- The seizure discharge is interrupted, producing intermittent muscle contractions that gradually decrease and finally cease. The epileptogenic neurons are exhausted.
- During seizure activity oxygen is consumed about 60% greater than normal. Although cerebral blood flow increases, oxygen is rapidly depleted along with glucose and lactate accumulates in brain tissue.
- Continued seizure activity has the potential for progressive brain injury and irreversible damage
What labs/diagnostic tests do you need to diagnose a seizure?
- Good H&P
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24 hour continuous EEG is an crucial test for supporting the diagnosis of epilepsy, differentiating types of seizures, and providing a guide to prognosis
- A normal EEG does NOT rule out a seizure
- CT or MRI of the head- should be obtained on all new onset seizure patients, especially after age 30 because of probability of underlying neoplasm
- MRI preferred over CT in non-emergent cases
- Lumbar puncture (only if indicated) to rule out infectious process after CT scan has ruled out expanding mass that may increase intracranial pressure.
- Serum labs:
- CBC
- Glucose, liver and renal function tests
- Venereal Disease Research Laboratory (VDRL) testing
- Electrolytes
- Magnesium
- Calcium
- Antinuclear antibody
- Erythrocyte sedimentation rate
- Arterial blood gases
- Urinalysis, drug screen
- Serum prolactin: rises 2 to 3 times above normal for 10-60 minutes after occurrence of 80% of tonic-clonic or complex partial seizures
What are the 4 steps to managing patients with status epilepticus?
1. Benzodiazepines first line treatment - rapidly able to control seizures
- Lorazepam 0.1mg/kg (4-8 mg with max dose of 10mg) at 2mg/minute IV
- Diazepam 0.1mg/kg at 5mg/minute with a max dose of 20mg IV
- Midazolam 0.1-0.3 mg/kg IV for a max dose of 10mg (only if IV lorazepam is unavailable)
- Monitor for respiratory depression post medications*
- Increase 0.9NS if* patient becomes hypotensive
2. Other Medications:
- Phenytoin should be administered simultaneously with lorazepam or diazepam and saline at 50mg/min until a loading dose of 20mg/kg is reached
- Fosphenytoin does not irritate the veins and can be given with all common IV solutions; it may be administered more quickly than phenytoin (150mg/minute vs 50mg/minute) without risk of cardiovascular collapse; it is all very expensive
3. If the above measures are unsuccessful to abort status epilepticus: intubate and administer phenobarbital 100mg/minute IV to a maximum of 20mg/kg.
4. If still unsuccessful after 60 minutes: consider general anesthesia with propofol, loading dose of 3-5 mg/kg followed by an infusion of 30-100mcg/kg/min
Abnormal seizure activity MAY continue despite neuromuscular blockage and endotracheal intubation
What are the 4 common causes of seizures in adults older > 65 years old?
- 1. Acute stroke: MOST COMMON cause of acute symptomatic seizures, accounting for up to ½ of cases.
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2. Metabolic encephalopathy: cause approx. 1/3 of acute symptomatic seizures in older adults
- Hypo- and hyperglycemia, hyponatremia, hypocalcemia, uremic and hepatic encephalopathy are all causes of seizures
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3. Drugs: drugs and drug withdrawal are responsible for up to 10% of seizures in the older adult
- Older adults particularly susceptible to drugs/drug withdrawal seizures due to polypharmacy, impaired drug clearance, heightened sensitivity; also can occur with alcohol, benzodiazepine or barbiturate withdrawal
- Other: trauma (falls) - low percentage of causative factor in seizures in older adult.
- 4. Alzheimer dementia (AD)– significant risk factor for epilepsy; between 10-20 % of patients with AD will develop seizures
What is the most common type of seizure in an older adult (>65 years old)?
Most seizures in older adults are focal onset; with or without evolution to a bilateral tonic-clonic seizure
What are the symptoms associated with a focal seizure in an older adult?
- Classic descriptions of aura, and olfactory hallucinations are less common in the older adult
- Nonspecific symptoms include: vaguely localized paresthesia’s, dizziness and muscle cramps; observes may notice episodic confusion, sleepiness or clumsiness rather than tonic or clonic movements
- Due to atypical symptomatology, older patients with seizures may be more frequently misdiagnosed- often diagnosed with altered mental status, confusion, blackout spells, memory disturbance, syncope, dizziness and dementia
How often does Status Epilepticus occur in older adults and what are the 2 types of status epilepticus?
- It occurs frequently in the older adult population (2x that of the regular population and was the mode of presentation for 1st seizure in 30% of older individuals in one hospital-based study)
Types:
- Convulsive SE: Stroke, either acute or remote, is the MOST frequent underlying etiology; Associated mortality is higher in older patients
- Non-convulsive SE: Difficult diagnosis to make particularly in the older patient; manifests as altered mental status with confusion, psychosis, lethargy or coma;
What are some differential diagnoses to consider when diagnosing an older adult with a seizure?
- Cardiac arrhythmias
- Metabolic disturbances
- Transient ischemic attacks
- Syncope
- Delirium
- Sleep disorders
