This is a focal motor seizure type or focal motor status epilepticus and not an epileptic syndrome.

Prevalence
Very small.

Age at onset
Any age; 1/3 <16 years.

Sex
Males = females.

Neurological and mental state
Usually normal, depending on etiology.

Etiology
Multiple and diverse: focal or multifocal brain lesions, systemic diseases affecting the brain and metabolic or other derangements; Kozhevnikov-Rasmussen syndrome and malformations of cortical development are the main causes in children. Cerebrovascular disease and brain space occupying lesions are the main causes in adults. Non-ketotic hyperglycemia is the most common of the reversible causes. An ‘encephalitic process’ is found in >50%.

Russian spring-summer tick-borne encephalitis is an endemic cause.

Pathophysiology
The epileptogenic generators are mainly in the primary motor cortex.

Clinical manifestations
The cardinal and defining symptom is epilepsia partialis continua.

Nearly all patients also have other seizures such as motor focal seizures in the same side and secondarily generalized tonic-clonic seizures. These may start before or after the onset and more often interspersed with epilepsia partialis continua.

Precipitating factors
Sometimes movement action or sensory stimuli.

Diagnostic procedures
The yield of investigative procedures is cause dependent. Around 2/3 have an abnormal brain MRI and EEG that become worse in progressive disorders such as Kozhevnikov-Rasmussen syndrome. PET and SPECT scans often localize the abnormal region but they are not specific. Screening for metabolic and mitochondrial disorders may be needed.

Inter-ictal EEG
Normal initially but soon after deteriorates, with high-amplitude focal or diffuse slow waves often dominating in one hemisphere. Poverty of physiological rhythms in the affected side. Inter-ictal multifocal spikes or sharp and slow waves in nearly all EEGs.

Ictal EEG
Epilepsia partialis continua is notorious with regard to lack of clinico-EEG correlations; epileptiform abnormalities may or may not be concomitant with the jerks. Typically, jerk-locked back-averaged cortical potentials appear in the contralateral primary motor area preceding the jerks by a few msec, sensory evoked potentials are of high amplitude and there is a rostro-caudal pattern of muscle recruitment with co-contraction of agonists and antagonist muscles.

Prognosis
Usually bad, often associated with residual or progressive neurocognitive deficits.

Differential diagnosis
Encephalitis of any cause. Kozhevnikov-Rasmussen syndrome.

Management options*
Seizures are resistant to AEDs. Clonazepam, valproate, levetiracetam, or carbamazepine may be considered.

*Expert opinion, please check FDA-approved indications and prescribing information

This page was adapted from:

The educational kit on epilepsies
The epileptic syndromes
By C. P. Panayiotopoulos

Originally published by MEDICINAE
21 Cave Street, Oxford OX4 1BA
First published 2006 and reprinted in 2007

Reviewed and revised June 2008 by Steven C. Schachter, MD