FOCAL EPILEPTIC MYOCLONUS: DIFFERENTIAL DIAGNOSIS AND PROGNOSIS

The paper describes the clinical, electroencephalographic (EEG), and neuroimaging features of focal epileptic myoclonus (FEM) and the results of therapy in patients with this type of seizure. The latter was identified in 2.5 % of the cases of epilepsy with onset beyond the age of 18 years (n = 1261). The age of onset of FЕМ was from 5 months to 23 years (mean 8.1 ± 1.6 years). The addition of secondary generalized seizures was stated in 90.3% of cases; that of focal motor seizures, epileptic aura, and negative FЕМ was seen in 64.5, 25.8, and 12.8 %, respectively. FЕМ was most commonly located in the flexor muscles of the upper extremities (22.6 %) and facial and upper limb muscles (25.6 %). The regional epileptoform
activity maximally located in the frontocentroparietal leads is a typical EEG pattern of FЕМ in all the patients. Magnetic resonance imaging most frequently revealed diffuse cortical and subcortical atrophy (29 %) and total cortical hemiatrophy (32 %). There was no case of complete remission of FЕМ. Monotherapy with antiepileptic drugs (AEDs) resulted in reduction of FЕМ in only 6.4 % of cases. During duo therapy, there was more than a 50 % reduction in FЕМ in 67.7 %. Our investigation has indicated that active FЕМ is a seizure type resistant to AEDs. This fact necessitates the detection of FЕМ at its early stages in order to predict the course of the disease and search for new therapies for epileptic syndromes associated with this type of seizures.

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