Familial paroxysmal exercise-induced dyskinesia, epilepsy, and mental retardation in a family with autosomal dominant inheritance.

Only few sporadic and familial cases of paroxysmal exercise-induced dyskinesia (PED) have been described in literature. PED associated with familial epilepsy has been rarely reported. We describe a family in which six members in different generations were affected by a long-lasting PED, with childhood onset in five cases. Fasting and stress were also precipitating factors. All the subjects, moreover, showed epileptic seizures during childhood and adolescence. In addition, in all cases a condition of mild mental retardation was also documented, associated in some cases, with irritable and impulsive behaviour. Clinical, neurophysiological, neuroimaging and neuropsychological findings were reported. The homogeneous recurrence of this particular clinical picture in members of three generations emphasised a common genetic basis. In our patients, PED is transmitted as an autosomal dominant trait, with age-dependent penetrance, without evidence of genetic anticipation. The neurophysiological findings suggest a condition of hyperexcitability in the muscular and brain membrane, due to a ion channels disorder.

Familial paroxysmal exercise-induced dyskinesia and benign epilepsy: a clinical and neurophysiological study of an uncommon disorder.

We report a family with 6 members affected by a long-lasting paroxysmal exertion-induced dyskinesia. Fasting and stress were precipitating factors. All the patients of this family had also epileptic seizures mainly of generalised type with a favourable outcome. All patients were submitted to a neurophysiological study which included somatosensory evoked potentials by median nerve stimulation (MN-SEPs), somatosensory evoked potentials by posterior tibial nerve stimulation (PTN-SEPs), brainstem auditory evoked potentials (BAEPs), visual evoked potentials (VEPs), motor evoked potentials (MEPs) by magnetic transcranial cortical stimulation (TCS) and electromyography (EMG). The neurophysiological findings suggest a hyperexcitability at the muscular and brain membrane levels, probably due to an ion channel disorder.