Spinal muscular atrophy and progressive myoclonic epilepsy: one case report and characteristics of the epileptic syndrome.

Spinal muscular atrophies (SMAs) are a group of degenerative diseases primarily affecting the anterior horn cells of the spinal cord and motor cells of cranial nerve nuclei. Even if the clinical picture is mainly dominated by the diffuse muscular atrophy, in some cases, patients may show associated, atypical clinical features ("SMA plus"). In particular, the association of SMA and progressive myoclonic epilepsy (PME) has been rarely described.We present the clinical and electrophysiological data of a boy with childhood-onset SMA associated with PME and reviewed cases of the literature.The association of SMA with PME may constitute a separate and, probably, genetically independent syndrome with unique clinical and electroencephalographic findings or, at least, a variant of a neurodegenerative or metabolic disease, due to yet unknown causes.