# Handbook of Genetic Counseling/Epilepsy and Seizures

Epilepsy and Seizures

## Background

* Epilepsies
** Group of disorders characterized by chronic, recurrent changes in neurologic function
** Caused by abnormalities in electrical activity of brain
** An individual with isolated, nonrecurrent seizures who are otherwise healthy do not have epilepsy
** Prevalence is 0.5-1.0% in general population
* Seizures
** An episode of neurologic dysfunction
** Convulsive seizures are accompanied by motor manifestations or other changes in neurologic function
*** Sensory
*** Cognitive
*** Emotional
** Classification is based on electroencephalographic pattern, clinical seizure type, and clinical context
*** Age of patient
*** Type of seizure
*** Presence of neurologic lesions

## Classifications and Clinical Findings

* Partial or focal seizures
** Begin with activation of neurons in only one part of the brain
** Specific clinical symptoms depend on area of brain involved
** Potential causes
*** Birth injury
*** Postnatal trauma
*** Tumor
*** Abscess
*** Infarction
*** Vascular malformation
*** Structural abnormality
** Two subclassifications
*** Simple if no alteration in consciousness
*** Complex if lose awareness of the environment
** Simple partial seizures
*** Recurrent contractions of muscles of one part of body without loss of consciousness
*** May remain confined to one area of body or spread to surrounding parts
*** May cause sensory symptoms (hallucinations) or psychic symptoms (unwarranted emotions)
** Complex partial seizures
*** Episodic changes in behavior causing a loss of conscious contact with environment
*** May begin with illusions, hallucinations, feeling of déjà vu, or unusual smell
*** May see lip smacking, swallowing, walking aimlessly , automatisms, or unconscious performance of highly skilled activities
*** When seizure ends, individual experiences amnesia
** Secondary generalization of partial seizures
*** Progression of partial seizure to loss of consciousness and convulsive motor activity
*** May happen after a few seconds or a few minutes
* Primary generalized seizures
** Tonic-clonic (Grand mal)
*** Usually begin without warning
*** Cause sudden loss of consciousness, tonic contraction of muscles, loss of posture control, and cry as respiratory muscles contract
**** Individual may sustain injury when they fall to the floor
**** May suffer cyanosis if respiration inhibited
*** Clonic period of rhythmic contractions of all four limbs that lasts for variable period of time
*** Headaches, drowsiness, amnesia, incontinence, and tongue biting may occur
** Tonic seizures
*** Sudden occurrence of rigid posturing of limbs and torso
*** Not followed by clonic phase and shorter in duration
** Absence seizures (petit mal)
*** Sudden cessation of ongoing conscious activity
*** No convulsive muscular activity or loss of postural control
*** So brief they may not be apparent but may cause lapse of consciousness or awareness accompanied by minor motor manifestations
*** Usually begin in children 6-14
**** Often appear neurologically normal
**** Usually sensitive to antiepileptic drugs
**** 1/3 outgrow disorder, 1/3 continue to have only absence seizures, 1/3 have tonic-clonic seizures
** Atypical absence
*** Similar to absence seizures by coexist with other forms of seizures
*** Occur in children with underlying neurologic dysfunction
*** Resistant to medication
** Myoclonic seizures
*** Sudden, brief, single or repetitive muscle contractions involving one body part or entire body
*** May occur alone or with other types
*** Symptom of medical conditions
**** Uremia
**** Hepatic failure
**** Creutzfeldt-Jakob Disease
**** Subacute leukoencephalopathies
**** Lafora body disease
**** Juvenile Myoclonic Epilepsy (JME)
** Atonic seizures
*** Brief loss of posture and consciousness
*** No muscular contraction
*** Usually occur in children
** Infantile spasms or hypsarrhthmia
*** Occur in infants birth to 12 months
**** All signs of seizures disappear from ages 3-5
**** Suffer other types of generalized seizures later in life
*** Contractions of neck, torso, and both arms
*** Usually occur in children with neurological disease
**** Tuberous sclerosis
**** Anoxic encephalopathy
*** 90% of these children develop mental retardation
** Febrile seizures
*** Controversial definition, prognosis, treatment, pathophysiology
*** Associated with fever but no evidence of intracranial infection or other cause
*** Usually occur from 3 months to 5 years of age
*** 2-6% go on to develop epilepsy
*** Estimated to occur in 2-5% of all Caucasian children
*** Family history reported in 7-58% of all children with these seizures
**** 8-15%% of first degree relatives may also be affected
**** Multifactorial inheritance
*** Recurrence risks for children of affected proband
**** 18.5% if only proband affected
**** 36.5% if proband and one parent affected
**** 45% if proband and both parents affected

## Genetic Etiology

* Genetic influences may be chromosomal, dominant or recessive autosomal, X-linked, or multifactorial
* Environmentally induced seizures carry low recurrence risk for other family members

## Differential Diagnosis

* Syncope
** Fainting or a sudden loss of consciousness not involving convulsions
** If origin unknown, patient should undergo cardiovascular evaluation, EEG with sleep recording, and prolonged ambulatory EEG monitoring
* Transient ischemic attacks and migraines
** Transient alteration in neurologic function without loss of consciousness
** Can undergo MRI or CT scan, carotid studies, and EEG precedures
** Antiepileptic drugs may help migraines
* Pseudoseizures and "hysterical seizures"
** Patients may appear emotionally disturbed and receive psychiatric treatment
** Normal EEG but may have activity in deep temporal lobe not detected
** May be eliminated or reduced by suggestion

## Treatment and Management Options

* Eliminate cause, suppress expression, and deal with psychosocial consequences
* May be treated by correcting metabolic disturbance, hormonal disruptions, etc.
* Pharmacologic control
** Goal is to prevent seizures without interfering with cognitive function
** Many patients are resistant to medication
** Teratogenic
* Neurosurgical treatment
** Remove structural lesion and nearby diseased part of brain (e.g. - tumor)
** May not help eliminate psychological disturbances that may occur

## Psychosocial Issues

* Anxiety over potential future development of epilepsy
* Complications associated with pregnancy
* Difficulty assessing exact recurrence risks
* Frustration if unknown etiology or explanation
* Social stigma associated with neurological disorders
* Fear of potential seizures at school, in public, etc.

## References

* Bird TD. "Epilepsy." The Genetic Basis of Common Disease. New York: Oxford University Press (1992).
* Dichter MA. "The Epilepsies and Convulsive Disorders." Principles of Internal Medicine. McGraw Hill, Inc. (1994).

## Notes

The information in this outline was last updated in 2002.