Hereditary neuropathy with liability to pressure palsies in childhood: Case series and literature update.

Hereditary Neuropathy with Liability to Pressure Palsy (HNPP) is a rare condition in childhood with a diverse range of clinical presentations. We analyzed the clinical presentation and electrophysiological data of 12 children with a confirmed PMP22 gene deletion and reviewed the published reports of HNPP in children and compared our data with the reports from the literature review. Peroneal palsy was the most common presentation (42%) followed by brachial plexus palsy in 25% of our cases. Nerve conduction studies were always suggestive of the diagnosis demonstrating 3 major patterns: multifocal demyelination at the area of entrapment, generalized sensory-motor polyneuropathy and a combination of the two first patterns in a vast majority (60%). Surprisingly, there was bilateral or unilateral electrophysiological entrapment of the median nerve at the carpal tunnel in all our patients. The clinical presentation of HNPP in childhood is heterogeneous and electrophysiological findings are helpful in establishing the diagnosis. Any unexplained mononeuropathy or multifocal neuropathy should lead to PMP22 gene testing to look for the deletion. Early diagnosis is important in order to facilitate appropriate genetic counseling and also for the appropriate care for these patients.