severe myoclonic epilepsy of infancy(redirected from epileptic encephalopathy, early infantile, 6)
severe myoclonic epilepsy of infancyA 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.
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]
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.
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 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
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.
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.
benign partial epilepsy of childhoodBenign rolandic epilepsy.
benign rolandic epilepsy
catamenial epilepsyMenstrual epilepsy.
familial myoclonic epilepsyLafora disease.
juvenile myoclonic epilepsy
Lennox-Gastaut syndrome epilepsySee: Lennox-Gastaut syndrome
medically intractable epilepsyIntractible epilepsy.
psychomotor epilepsyTemporal lobe epilepsy.
severe myoclonic epilepsy of infancyDravet syndrome.
temporal lobe epilepsy
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)
Surgery to remove the irritable focus in the brain appears more effective than treatment with anticonvulsant drugs.