Acute psychological disorders in patients with epilepsy: a nation-wide study.

Acute psychological disorders (APDs) are more common in epilepsy than in the general population, with estimates varying from 2 to 16% depending on the population of patients sampled. APD has traditionally been classified by seizure activity (ictal), the early post-ictal period (post-ictal) and unrelated to seizure activity (inter-ictal). APD may also occur as a consequence of the use of antiepileptic drugs (AEDs). An ongoing prospective active surveillance system was utilised which surveys all neurologists and associated specialists in the United Kingdom run by the British Neurological Surveillance Unit (BNSU). Incident cases were ascertained, using the BNSU, for a period of 1 year and were defined as patients with epilepsy who developed an acute psychological disorder, whatever the cause, such as a psychosis or depression. Sixty-four cases were ascertained. The ages were between 17 and 69 (mean 36); there were 38 males and 26 females. The majority of patients had location-related epilepsy (52, 81%), either cryptogenic (29, 45%) or secondary to a symptomatic lesion (23, 36%), of which the most common were mesial temporal sclerosis (6, 9%) and trauma (4, 6%). Thirty-one (48%) patients were considered to have APD due to ictal or post-ictal activity. Thirty-three (52%) were inter-ictal. Carbamazepine was the most common AED prescribed (42, 66%), and of the new AEDs lamotrigine was prescribed in 17 patients (27%) and vigabatrin in 16 (25%). The APD in 19 (30%) patients was reported by the referring physician as being secondary to an AED. In 12 patients this was attributed to vigabatrin. However, the relative frequency of APD due to AEDs, or to the different new AEDs, could not accurately be calculated as this was not a true incidence study. In the 19 drug-related APD patients, there was no change in seizure frequency in 8 (42%) and in 7 (37%) the seizure frequency had decreased (in 3 (16%), ceasing altogether prior to the APD). In 4 of the 19 patients (21%) the seizure frequency increased. The overall outcome was good with 17/19 (89%) of the AED attributed cases resolving.