CLINICAL AND PHYSIOLOGICAL FEATURES OF EPILEPSIA PARTIALIS CONTINUA -CASES ASCERTAINED IN THE UK

Epilepsia partialis continua (EPC) is defined clinically as a syndrome of continuous focal jerking of a body part, usually localized to a di stal limb, occurring over hours, days or even years. The anatomical an d physiological origin of EPC has been the subject of much speculation . It has been argued that EPC is a form of focal cortical myoclonus, b ut subcortical mechanisms have also been proposed. We describe a serie s of 36 patients ascertained over a period of I year in the UK using t he British Neurological Surveillance Unit. The commonest aetiologies i dentified were Rasmussen's syndrome (n = 7; 19%) and cerebrovascular d isease (n = 5; 14%). Rasmussen's syndrome was the most common diagnosi s in patients under 16 years. Irt seven patients the cause remained un known. Eight patients (22%) had focal epileptiform scalp EEC abnormali ties, and 56% had generalized background scalp EEG disturbances. Lesio ns on MRI or CT were found in 20 cases (56%), half of whom showed pred ominant cortical involvement. The muscle jerking resolved in four pati ents (with no treatment in one), with a partial response to treatment in seven (19%) patients. A cognitive or neurological decline had been noted retrospectively in 13 (36%) patients (and in all of the patients with Rasmussen's syndrome). We personally saw 16 patients who underwe nt detailed clinical and neurophysiological assessments. Only six of t he patients had EEG and EMG evidence for a cortical origin of their je rks; Jive others had indirect evidence for a cortical origin, from EMG , magnetic stimulation, and other investigations. Two patients did not have myoclonus of cortical origin, but some other source (brainstem a nd basal ganglia). The origin in the remaining three patients was unce rtain. The clinical appearance of the muscle jerks was similar in all patients despite the different origins. We propose that the definition of EPC is best restricted to 'continuous muscle jerks of cortical ori gin'. Continuous muscle jerking that arises from other sites in the ne rvous system should be termed 'myoclonia continua'.