Epilepsia partialis continua in tick-borne Russian spring-summer encephalitis

Epilepsia partialis continua (EPC) is characterized by localized continuous jerks, from time to time with spreading Jacksonian seizures and, more rarely, secondarily generalized tonic-clonic seizures. EPC has numerous possible etiologies. In this paper we describe EPC in the tick-borne Russian spring-summer encephalitis (TBRSSE) and compare it with Rasmussen syndrome.

We included patients with EPC in TBRSSE (between 2003 and 2010). The diagnosis was verified by immunology (antibodies against TBRSSE virus). The patients were followed 1-7 (mean 3.4) years.

We studied 10 patients (eight males, age 10-21 years) with MRI and video-EEG. Nine developed EPC after acute TBRSSE (meningoencephalitic form), and one had a tick bite without clinical symptoms of encephalitis, but with subsequent EPC. All patients came from Ural and Siberia. The onset was at age 4-14 (mean 8.6 years). The interval from onset of TBRSSE or the tick bite to seizure onset was 1 day-4 years. We identified three phases of clinical course EPC in TBRSSE: (i) acute (meningoencephalitic/encephalitic); (ii) development of EPC; and (iii) chronic EPC. The effect of antiepileptic drugs differed according to seizure types.

EPC caused by TBRSSE is relatively frequent in the Eastern parts of the Russian Federation but not west of the Ural. Unlike Rasmussen encephalitis, EPC with TBRSSE does not progress even in the long term. It appears as disabling but not fatal condition with a time course where three phases can be distinguished.