severe myoclonic epilepsy of infancy

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severe myoclonic epilepsy of infancy

A rare disorder (OMIM:607208) characterised by generalised tonic, clonic and tonic-clonic seizures triggered at first by fever and arising shortly after birth. Later, patients also manifest other seizure types, including absence, myoclonic, and simple and complex partial seizures. Psychomotor developmental delay appears by the second year of life. SMEI is the most severe phenotype in the spectrum of generalised epilepsies with febrile seizures-plus.

Molecular pathology
Defects of GABRG2, which encodes a subunit of a ligand-gated ionic channel that plays a key role in inhibiting neurotransmission, cause severe myoclonic epilepsy of infancy.

epilepsy

(ep'i-lep?se) [L. epilepsia fr. Gr. epilepsia, (epileptic) seizure]
A disease marked by recurrent seizures, i.e., by repetitive abnormal electrical discharges within the brain. Epilepsy is found in about 2% or 3% of the population. Its incidence is highest in children under 10 and in the elderly (over 70); adolescents and adults are affected less frequently.

The International League Against Epilepsy categorizes epilepsy as partial, generalized, drug-resistant, or unclassified. Partial seizures typically begin with focal or local discharges in one part of the brain (and body); sometimes they may become generalized. When a patient remains awake during a seizure, the seizure is said to be simple and partial. If loss of consciousness occurs after a focal seizure, the seizure is said to be partial and complex. Drug-resistant epilepsy is a failure to control seizures despite adequate trials of two appropriately chosen and dosed antiepileptic drugs. .

Patients who suffer recurrent episodes of alcohol withdrawal or frequent severe hypoglycemia, hypercalcemia, or similar metabolic illnesses may have repetitive seizures but are not considered to have epilepsy if the seizures stop after their underlying illnesses are treated.

Etiology

Epilepsy may result from congenital or acquired brain disease. Infants born with lipid storage diseases, tuberous sclerosis, or cortical dysplasia, e.g., may have recurrent seizures, as may children born with intracranial hemorrhage or anoxic brain injury. Adults may develop epilepsy as a result of strokes, tumors, abscesses, brain trauma, encephalitis, meningitis, uremia, or other illnesses. In many instances the underlying cause is undetermined.

Symptoms

Symptoms may vary from the almost imperceptible alteration in consciousness, as in absence seizures, to dramatic loss of consciousness, tonic-clonic convulsions of all extremities, urinary and fecal incontinence, and amnesia for the event. Some attacks are preceded by an aura; others provide no warning. Other forms are limited to muscular contractions of a localized area or only one side of the body. See: postictal confusion

Diagnosis

The diagnosis of epilepsy is made by a careful assessment of the patient's history, augmented by diagnostic studies. Typically, these include blood tests to assess for metabolic disarray, brain imaging using magnetic resonance imaging or computed tomography, and electroencephalography. The differential diagnosis of epilepsy includes many other illnesses marked by episodes of loss of consciousness, including pseudoseizures, syncope, transient ischemic attacks, orthostatic hypotension, and narcolepsy.

Treatment

Therapy is available for the prevention and control of recurrent seizures. Antiepileptic agents include phenytoin or carbamazepine for partial seizures, valproic acid for absence seizures, and any of these agents or phenobarbital, with or without newer drugs, e.g., gabapentin or lamotrigine, for generalized seizures. All these agents may have significant side effects, and many of them have a range of drug-drug interactions.

Surgical therapy to remove an epileptic focus within the brain is used occasionally to manage seizures that have been difficult to control medically. In specialized neurosurgical centers, this may cure or reduce the impact of epilepsy in about 75% of patients.

auditory epilepsy

Epilepsy triggered by certain sounds.

benign partial epilepsy of childhood

Benign rolandic epilepsy.

benign rolandic epilepsy

Repetitive seizures usually perceived as facial or oral movements or paresthesias, typically affecting children at night. The seizures sometimes generalize (cause tonic/clonic convulsions). Affected children usually outgrow the disease by the end of adolescence. Synonym: benign partial epilepsy of childhood.

catamenial epilepsy

Menstrual epilepsy.

familial myoclonic epilepsy

Lafora disease.

intractible epilepsy

Epilepsy that cannot be controlled by two or more anticonvulsant drugs.
Synonym: medically intractable epilepsy

juvenile myoclonic epilepsy

A form of epilepsy typically noticed in teenagers, characterized by early morning jerking movements of the extremities, and during stress or sleep deprivation, generalized tonic/clonic or absence seizures.
Synonym: Janz syndrome.

Lennox-Gastaut syndrome epilepsy

See: Lennox-Gastaut syndrome

medically intractable epilepsy

Intractible epilepsy.

menstrual epilepsy

Seizures that occur preferentially during particular portions of the menstrual cycle, e.g., during ovulation or menses.
Synonym: catamenial epilepsy

musicogenic epilepsy

Epilepsy in which the convulsive attacks are induced by music.

photogenic epilepsy

Epilepsy that occurs as a result of intermittent light stimulus.

psychomotor epilepsy

Temporal lobe epilepsy.

reflex epilepsy

Recurrent epileptic seizures that occur in reaction to a specific stimulus, e.g., photic stimulation while looking at flashing lights or television, auditory stimulation while listening to specific musical compositions, tactile stimulation, or reading.

refractory epilepsy

Epilepsy that cannot be controlled with two anticonvulsant drugs. Refractory epilepsy is found in about a third of all patients who have seizures.

sensory epilepsy

Disturbances of sensation without convulsions.

severe myoclonic epilepsy of infancy

Dravet syndrome.

sleep epilepsy

A term formerly and improperly used for narcolepsy.

temporal lobe epilepsy

Epilepsy originating in a temporal lobe of the brain. See: psychomotor epilepsy

Symptoms

Temporal lobe seizures produce one of two typical findings: (1) complex partial seizures (loss of consciousness with abnormal gesturing or automatic movements); and (2) simple partial seizures (preserved consciousness with the sense of unusual smell, taste, thought, or altered body function)

Treatment

Surgery to remove the irritable focus in the brain appears more effective than treatment with anticonvulsant drugs.

traumatic epilepsy

Epilepsy caused by trauma to the brain.

uncinate epilepsy

An old term for temporal lobe epilepsy, which arises from a focus in the uncinate area of the temporal lobe of the brain.

vasomotor epilepsy

Epilepsy with vasomotor changes in the skin.
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