J. Layne Moore, MD, MPH
Charles W. Hall Jr., MD, PhD
DESCRIPTION
- Epileptic seizures represent episodes of uncontrolled electrophysiological activity in the brain. This may manifest as sensory or motor activity, behavioral arrest, confusion or as convulsive activity.
- Most seizures begin focally (partial) and then spread.
- If consciousness is not lost (only sensory or motor symptoms), the seizure is Simple Partial.
- If consciousness is impaired, it is referred to as Complex Partial.
- If a convulsion ensues, it is called Secondary Generalized.
EPIDEMIOLOGY
Incidence
- The incidence is bimodal being highest in the 1st year and 7th decade.
- Prevalence: Approximately, 1.5% of the USA has a diagnosis of epilepsy.
RISK FACTORS
- Nearly 70% of epilepsy is cryptogenic, meaning that a causative etiology is not identified.
- A history of stroke is found in 15% of patients.
- About 5% of patients are found to have a developmental anomaly such as focal cortical dysplasia or gray matter heterotopias.
- Serious head injury
- Brain tumor
- CNS infections
- Neurodegenerative syndromes (1)[B]
Genetics
For most forms of epilepsy, the inherited risk is polygenetic. The risk of an affected parent passing on the disease is 3–4%.
GENERAL PREVENTION
Reducing the risk of injury to the central nervous system by way of infections or trauma reduces the risk of developing acquired epilepsy. The risk of epilepsy increases with economic deprivation and substance abuse.
PATHOPHYSIOLOGY
An imbalance of excitatory and inhibitory control of the neocortex for various reasons.
ETIOLOGY
No single etiology is present but injuries to the neocortex via foreign tissue lesions, strokes, infections or trauma predispose individuals. Most patients have none of those risk factors.
COMMONLY ASSOCIATED CONDITIONS
Co-morbidities include headache, cognitive impairment, depression and anxiety.
HISTORY
- Does the patient have a history of head injury with loss of consciousness, stroke (ischemic or hemorrhagic), CNS infections (viral, fungal, and bacterial), cocaine or alcohol abuse, febrile seizures, tumors, cortical malformations or vascular malformations? Also a family history increases the risk of developing epilepsy.
- Most persons with complex partial seizures describe brief lapses in awareness that impair task performance with confusion thereafter.
- Seizures of temporal onset consist of behavioral arrest or staring off, lip smacking or chewing, and semi-purposeful movements of the hands and feet (automatisms).
- Frontal lobe seizures tend to be nocturnal and violent. Many persons with frontal lobe seizures exhibit seemingly purposeful aggression.
- Children with Rolandic epilepsy tend to have simple partial seizures involving twitching motions of the face during the daytime hours, and violent generalized tonic clonic convulsions at night.
- Of all seizures, 90% last less than 2 minutes and longer duration spells may not be seizures.
- Some patients may experience bladder incontinence or tongue biting.
- Up to 10% of cases of new onset epilepsy present with status epilepticus.
PHYSICAL EXAM
A careful neurological examination including motor and sensory components.
DIAGNOSTIC TESTS AND INTERPRETATION
Lab
Initial Lab Tests
- MRI brain
- An awake and sleep EEG
- Antiepileptic drug (AED) levels
- UA, CBC and électrolyte panel with calcium, magnesium and phosphorous (Ca, Mg)
- Toxicology screen
- TSH
- Pregnancy test
Follow-Up & Special Considerations
- Patients must be seizure-free to operate a motor vehicle or engage in dangerous activities. Various state laws dictate the duration that a patient must be seizure-free to drive. If your state does not dictate a certain length of time for seizure-freedom, a minimum of 3 months is advisable (3)[B].
Imaging
Initial Approach
- CT scans of the brain are appropriate for emergent evaluation of acute new-onset seizures or for persons with contraindications for MRI imaging.
- MRI of the brain with thin cuts-oriented perpendicular to the long axis of the hippocampus are desirable.
Follow-Up & Special Considerations
- Patients are re-evaluated based on how frequently they are having seizures.
- Complete control is necessary for patients to drive and engage in dangerous activities.
Diagnostic Procedures/Other
- Inpatient video-EEG monitoring for spell classification, medication adjustment, seizure quantification, or presurgical evaluation
- Chronic intracranial monitoring
- Ictal or interictal SPECT
Pathological Findings
- Mesial temporal sclerosis with neuronal loss and reactive gliosis of amygdalohippocampal complex
- Encephalomalacia with hemosiderosis and gliosis in frontal and temporal poles due to head trauma with contusion
- Gray matter heterotopia (nodular and band) with gray matter appearing in atypical locations
- Focal cortical dysplasia with balloon cells
- Polymicrogyri, pachygyri, schizencephaly
- Vascular malformations—arteriovenous malformations, dural arteriovenous fistulas, and cavernomas.
DIFFERENTIAL DIAGNOSIS
- syncope, or syncopal seizures
- nonepileptic psychogenic spells
- parasomnia/REM behavioral disorder
- narcolepsy/cataplexy
- confusional migraine
MEDICATION
First Line
Second Line
Pregnancy Considerations
- AEDs must not be stopped during pregnancy.
- The best approach is to anticipate pregnancy and have young women on AEDs that are safest for developing fetuses (lamotrigine, carbamazepine).
- Referral to high risk obstetrician for appropriate screening, possible antenatal Vitamin K (2)[B].
- All women of child-bearing potential should be on at least 1 mg of Folic acid daily before conception.
ADDITIONAL TREATMENT
General Measures
- Patients should have dosages changed for side effects and break-through seizures rather than using only “therapeutic level” monitoring.
- Periodic laboratory monitoring to screen for bone marrow suppression (agranulocytosis, aplastic anemia), liver inflammation (transaminitis), or electrolyte abnormalities (hyponatremia).
Issues for Referral
- Seizures that remain uncontrolled for more than a year.
- Failure of 2 or more anticonvulsant medications
- Episodes of status epilepticus
- Changes in seizure character
Additional Therapies
- Resective surgery
- Vagus nerve stimulator, reactive nervous stimulation, deep brain stimulation
- Ketogenic and modified adkins diets
- Corpus callosum section
SURGERY/OTHER PROCEDURES
- Vagus nerve stimulator
- Resective surgery of epileptic focus
- Corpus callosum section
IN-PATIENT CONSIDERATIONS
Initial Stabilization
Admission Criteria
- Seizures that last for more than 5 minutes are unusual and suggest the onset of an acute seizure condition or status epilepticus.
- Any change in the nature or duration of seizures
- Prolonged periods of confusion
IV Fluids
- Phenytoin may never be given with glucose in the IV fluids because it may crystallize.
Discharge Criteria
- Adequate control of seizures
FOLLOW-UP RECOMMENDATIONS
- Interval of follow up is based on frequency of seizures
Patient Monitoring
- Seizure control and side effects are most important for management
- Patients should be encouraged to keep seizure calendars.
- AED levels may be used adjunctively but are never the sole reason for changing dosages.
DIET
PATIENT EDUCATION
- Patients must be counseled about medication adherence.
- Driving restrictions
- Pregnancy
- Avoid activity in which abrupt loss of consciousness could cause injury to self/others.
- Shower rather than bath.
PROGNOSIS
- Of patients, 70% will obtain seizure-freedom for an extended period of time.
COMPLICATIONS
- Patients with epilepsy may injure themselves or die unexpectedly without apparent cause. This sudden unexpected death in epilepsy is uncommon but probably occurs more in uncontrolled patients.
