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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nonconvulsive status epilepticus (NCSE) is much more common than is generally appreciated and is certainly underdiagnosed, but its long-term effects are largely undetermined and remain controversial. There is increasing experimental evidence that generalized convulsive status epilepticus produces lasting neuropathologic damage in the hippocampus, but experimental models often include provocation of status epilepticus (SE) by physical (e.g., electrical stimulation) and chemical (including excitotoxic) agents that may induce damage independent of the epileptiform discharges. Also, damage appears to be related to the intensity and duration of electrical stimulation. Such models usually include high-frequency discharges sustained over long periods, somewhat different from the electrical activity of typical human NCSE. Pathologic studies in humans pertain primarily to patients who have had generalized convulsive status epilepticus. Clinical studies of the effects of NCSE are mandatory, but conclusions are difficult to come by, in part because of diverse definitions of NCSE. An altered mental status is obligatory, but the pertinent EEG and medication response criteria are controversial. Response to medication can be delayed by many hours or even days. Absence SE appears to cause no lasting effects. Complex partial SE is less uniform. Most reported cases have returned to baseline neurologic function, but several well-described patients have had prolonged memory deficits. The significance of other deficits is difficult to interpret in light of concomitant vascular and other diseases causing neurologic dysfunction. Clinical series usually lack premorbid neurologic and neuropsychologic assessment. The few exceptions are complicated by preexisting mental retardation and other deficits, by the coexistence of progressive illness, by the later effects of recurrent seizures, and almost always by the confounding influence of anticonvulsant medications. Most morbidity appears attributable to the underlying illnesses rather than to the NCSE itself. It is possible that relatively infrequent cases of prolonged NCSE or those with the synergistic effect of concomitant systemic illness, focal lesions, or very rapid excitatory epileptiform discharges may suffer more long-lasting damage, but these observations are still preliminary. NCSE should be treated expeditiously because of the acute neurologic impairment of the patients, because of the attendant morbidity including physical injury, and because it may go on to generalized convulsions. There is reasonable concern about possible long-term effects, but permanent neurologic damage from NCSE has not yet been established as a mandate for urgent treatment.
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PMID:Evidence against permanent neurologic damage from nonconvulsive status epilepticus. 1047 5

Nonconvulsive status epilepticus (NCSE) is characterized by behavioral or cognitive change from baseline for at least 30 minutes with EEG evidence of seizures. Categorized into complex partial status epilepticus (with lateralized seizures), and generalized nonconvulsive status epilepticus (bilateral diffuse synchronous seizures), there is debate regarding the diagnosis and morbidity of NCSE. Because EEG is needed for diagnosis, only a high index of suspicion leads to a request for the study, whereas EEG is often unavailable after hours or on weekends. Furthermore, the cognitive changes during NCSE are often incorrectly ascribed to a postictal state, intoxication, psychogenic or psychotic states, and mental retardation. Regarding categorization, present classifications address EEG features but fail to distinguish among depths of coma. Deeply comatose patients (with coma etiologies that themselves carry poor prognoses) are mixed with lightly obtunded patients with no morbidity, confusing the prognosis. Thus, a classification that subsumes depth of coma, and possibly etiology, is sorely warranted. Regarding treatment, comatose NCSE patients treated with benzodiazepines may worsen, whereas generalized nonconvulsive status epilepticus patients may suffer iatrogenically from aggressive treatment (hypotension and respiratory depression) necessitating balancing the potential neurologic morbidity of NCSE against the possible morbidity of IV antiepileptic drugs. A high index of suspicion is needed to initiate EEG studies. Better stratification of level of consciousness will be needed to distinguish among morbidity due to underlying conditions, treatment, and the effects of status epilepticus, proper.
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PMID:Assessing the outcomes in patients with nonconvulsive status epilepticus: nonconvulsive status epilepticus is underdiagnosed, potentially overtreated, and confounded by comorbidity. 1047 7

Ring (20) chromosome epilepsy syndrome is characterized by highly refractory epilepsy that is often associated with non-pathognomonic, electroencephalographic (EEG) changes. Seizures typically begin during the stage of childhood around the age of 6 years. Nonconvulsive status epilepticus (NCSE) is the most common seizure types and is distinguished by a long-lasting, confusional state that is often associated with EEG patterns in the form of prolonged, high-voltage slow waves with occasional spike/sharp components. Patients with this syndrome suffer from intractable seizures with cognitive decline and frequent epileptic episodes. Accompanying features of this rare disorder, such as superficial minor dysmorphic abnormalities if any, mental retardation and behavioral changes are quite variable. Because of the variability in clinical presentation, in particular the lack of clear dysmorphic features, the clinical diagnosis of this disorder can be delayed before being diagnosed genetically. Most patients with this syndrome have chromosomal changes in the form of a mosaic. High levels of mosaicism correlate well with a lower age of onset and severe cognitive impairment. Here, we emphasize the importance of early G-banding chromosomal analysis when patients present with unexplainable severe seizures and repetitive NCSE, even in the absence of any dysmorphic features suggestive of a chromosomal disorder.
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PMID:[Ring (20) chromosome epileptic syndrome]. 2595 5