An 18 old right-handed male presented to epilepsy clinic with a non-familial "seizure disorder". At 14 years of age he experienced his first generalized tonic-clonic seizure. Subsequently he developed multi-focal myoclonus and was diagnosed with Juvenile Myoclonic epilepsy. However, he gradually worsened with nearly continuous generalized myoclonus developing 3 years later. His grades fell and he developed an inability to walk and wheel-chair dependence by 19 years of age. He later became poorly communicative with dysarthria interrupted by continuous myoclonus. He was refractory to multiple broad-spectrum AEDs and required frequent hospitalizations for serial convulsions. His MRI brain was unrevealing and an EEG was abnormal (see below).
Figure: EEG demonstrating diffuse slowing of the posterior dominant rhythm punctuated by nearly continuous generalized spike and polyspike discharges. Note the occipital predominant sharp waves (arrow). EEG parameters include a bipolar montage, sensitivity of 7 uv/mm, and filters of 1-70 Hz.
The progressive myoclonus epilepsies (PME) are a group of disorders with myoclonus as a prominent clinical feature in addition to generalized, focal, and atypical absence seizures. Lafora Disease (LD) presents in early adolescence and may initially mimic IGE though progressively worsening myoclonus after an initial GTC signals a different course. Slow cognitive decline, visual impairment, visual hallucinations, and occipital seizures become evident. Progressive myoclonus, refractory epilepsy, dementia, ataxia, and speech dysfunction occurs. Total care is evident prior to a fatal demise which occurs within 10 years after onset. EEG changes may precede the clinical symptoms by 6 years. Diffuse slowing and generalized IEDs occur in virtually everyone. Slowing and loss of an alpha rhythm gradually became replaced by generalized IEDs with occipital predominance in addition to focal and multi-focal abnormalities. The IEDs wane during sleep unlike genetic generalized epilepsy where the IEDs become more prominent. Giant SSEPs were seen. A biopsy demonstrated Lafora bodies. He died at 21 years old.
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