A rare genetic disorder in the differential diagnosis of the entrapment neuropathies: hereditary neuropathy with liability to pressure palsies.

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal-dominant, slowly progressive neuromuscular disorder, which is characterized by recurrent acute peripheral nerve palsies. Electrophysiological studies show decreased motor and sensory conduction velocities in both clinically affected and unaffected nerves. Focal thickening of myelin sheath with sausage-like formation, also called tomacula, is seen in nerve biopsies. In genetic studies, 1.5-Mb deletion on chromosome 17p11.2 is detected in approximately 85% of HNPP cases and point mutations are determined in some cases. We describe a 26-year-old man who had a 6-month history of paresthesia in the little fingers of his hands. He was diagnosed with HNPP by neurologic examination, and electrophysiological and histopathologic studies. Studies in his mother and one brother also showed entrapment neuropathy. However, no deletions or point mutations were determined in this family. Other genetic defects apart from the known ones might be present in this disease. The most frequent entrapment syndrome, carpal tunnel syndrome, is also seen in this disease, so physicians dealing with musculoskeletal problems should be alert about this subject. Awareness of HNPP may help avoid unnecessary operative interventions.