Non-convulsive status epilepticus: a prospective study in an adult general hospital.

A prospective study of non-convulsive status epilepticus was undertaken in order to evaluate the occurrence and characteristics of this condition in adults. The diagnosis was established in 22 of 113 patients (19 per cent) presenting with status epilepticus over a 23-month period. Non-convulsive status was most prevalent in the over 60 age group. Its two subgroups, absence status (18 cases) and complex partial status (four cases) were both manifest clinically by a prolonged alteration of consciousness of variable extent. Absence status presented de novo (six cases) or against a background of epilepsy (12 cases), often with a long seizure-free interval before presentation. Precipitating factors included infection, inadequate anticonvulsant medication and benzodiazepine withdrawal. The clouding of consciousness was usually characterised by confusion, disorientation and partial responsiveness. Myoclonic or clonic movements of the eyes, face or jaw were evident in all but two patients. Automatisms, including ambulatory behaviour (three cases) were less common. Serious psychiatric disorders preceded the status in seven cases, and contributed to the difficulty in diagnosis. Complex partial status was associated with underlying cerebrovascular disease in three of four cases, and is characterised by a more severe and variable clouding of consciousness, less frequent facial clonic movements, episodic adversive head and eye movements, and a more gradual recovery after treatment.