Late onset myoclonic epilepsy in Down syndrome and dementia

Specific forms of epilepsy may be found at various ages in Down Syndrome (DS) and a sharp increase in the incidence of epilepsy with age has been documented. A specific type of myoclonic epilepsy associated with cognitive decline has been reported as "senile myoclonic epilepsy" or "late onset myoclonic epilepsy in DS" (LOMEDS). We report a new case of LOMEDS, documented by clinical and neurophysiological evaluation and psychometric assessment (DSDS and DMR). MF, male, affected by DS, was referred in 2004 at 40 years of age; he had no personal or familial history of epilepsy. Since one year, the patient presented cognitive deterioration, characterized by regression of language abilities, loss of memory, and loss of sphincters control. A brain TC showed mild brainstem and sub-cortical atrophy. In 2006, myoclonic jerks involving upper limbs occurred mainly after awakening. EEG showed a low voltage 8 Hz background activity with diffuse slow activity, intermingled with spikes or polyspikes, persisting during NREM sleep. MF was initially treated with clonazepam and after with topiramate, resulting in partial seizures control. MRI (2008) demonstrated diffuse brain atrophy, associated with marked ventricular enlargement. At the psychometric evaluation, onset of dementia was evident late in 2004, with transition to the middle stage in 2006. Last assessment (2009) showed the clinical signs of a late stage of deterioration, with loss of verbal abilities and autonomous ambulation. Using levetiracetam till 2,000 mg/die, myoclonic jerks decreased but are still present every day after awakening. On the EEG slow and poorly organized background activity with bilateral polyspike-wave discharges was recorded. Therefore, we documented a parallel progression of dementia and myoclonic epilepsy in a DS subject.