Logopenic syndrome and corticobasal dysfunction in a “benign” type 3 familial cortical myoclonic tremor with epilepsy

Myoclonic epilepsies are frequently related to mitochondrial disorders, lysosomal disorders and proteinopathic neurodegenerative diseases. Familial cortical myoclonic tremor with epilepsy (FCMTE) is a genetic form of myoclonic epilepsy. FCMTE is defined by an autosomal dominant inheritance, adult onset cortical myoclonic tremor and inconstant seizures. Electrophysiologic examinations show cortical hyperexcitability (paroxysmal polyspike and wave activity on EEG with a marked photosensitivity, recording of enlarged cortical components of somatosensory evoked potential, enhanced long-loop reflex (C-reflex), and cortical transients preceding the myoclonic jerks using the jerk-locked back-averaging technique). Type 3 FCMTE (FAME3/FCMTE3) is linked to the locus 5p15.31-p15.1 [1]. No obvious candidate gene (like ion channel subunit gene for example) is localized to this locus. Actually, no mutation has been found and the biological mechanism involved in FCMTE3 remains unclear. Fronto-striatal dysfunction, gait impairment and cognitive disorders appearing after several decades of disease progression were reported in FCMTE3 [2]. The patient was a right-handed 52-year-old man with high level of education. No previous personal medical history or neurodevelopmental disorder was reported. A generalized seizure was reported to have occurred at the age of 25, and with a mild bilateral myoclonus in upper limbs beginning at the age of