Pathognomonic

Abstract: Lennox-Gastaut syndrome is one of the most severe epileptic encephalopathies of childhood onset. The cause of this syndrome can be symptomatic (ie, secondary to an underlying brain disorder) or cryptogenic (ie, has no known cause). Although Lennox-Gastaut syndrome is commonly characterised by a triad of signs, which include multiple seizure types, slow spike-wave complexes on electroencephalographic (EEG) recordings, and impairment of cognitive function, there is debate with regard to the precise limits, cause, and diagnosis of the syndrome. Tonic seizures, which are thought to be a characteristic sign of Lennox-Gastaut syndrome, are not present at onset and the EEG features are not pathognomonic of the disorder. There are few effective treatment options for the multiple seizures and comorbidities, and the long-term outlook is poor for most patients. Probably as a result of the complexity of the disorder, only a few randomised trials have studied Lennox-Gastaut syndrome, and thus many of the drugs that are more commonly used have little or no supporting evidence base from controlled trials. In this Review, we discuss the main issues with regard to the diagnosis and treatment options available. We also suggest key considerations for future trials and highlight the importance of a comprehensive approach to the assessment and management of this syndrome.

Abstract: The need for operationalized criteria for the identification of schizophrenia is great. Schneider's diagnostic concept attempts the optimum in diagnostic clarity, using frequently occurring symptoms which can be reliably identified by various observers, and which he believes always indicate schizophrenia in the absence of an organic psychosyndrome. Schneider's approach, although never established by other investigators, is used for diagnosis throughout most of the world. We found that the first-rank symptoms (FRSs) occurred frequently enough in acute schizophrenia to have diagnostic applicability. Individually, each FRS was found with greater frequency in schizophrenia. However, taken together, these symptoms which he considers pathognomonic of schizophrenia occur in one fourth of the cohort of manic-depressive patients. Therefore, Schneider's system for identifying schizophrenia, while highly discriminating, leads to significant diagnostic errors if FRSs are regarded as pathognomonic. Furthermore, FRSs did not have a postdictive or predictive function, as no relationship could be established between FRSs and duration or outcome of illness.