Hereditary neuropathy with liability to pressure palsies: description of seven patients without known family history

OBJECTIVES: Hereditary neuropathy with liability to pressure palsies (HNPP) is an inherited disorder resulting in a polyneuropathy with particular involvement at sites of entrapment, and is often underdiagnosed or misdiagnosed. We report findings on seven patients referred for evaluation of focal mononeuropathies or polyneuropathies of undetermined etiology, in whom we established a diagnosis of HNPP. MATERIALS AND METHODS: We retrospectively reviewed clinical, electrophysiological and laboratory data for patients diagnosed with HNPP over a 4-year period at our institution. RESULTS: All patients had transient or recurrent neurological symptoms, some with residual deficits. No patients had a family history of any neuropathy. Electrodiagnostic studies revealed abnormal conduction findings at symptomatic and asymptomatic sites. Testing for the Peripheral Myelin Protein (PMP22) deletion was positive in all patients. CONCLUSIONS: A high index of clinical suspicion and thorough electrodiagnostic evaluation can lead to correct diagnosis of HNPP, despite the absence of a positive family history.