Abstracts

2354 Hereditary neuropathy with liability to pressure palsies (HNPP): two cases highlight the electrophysiological variability and associated diagnostic conundrum

Abstract

Method Case report

Objective We present two cases highlighting the variability of electrophysiological phenotype with HNPP creating a diagnostic conundrum given other potential causes of neuropathy.

Results Case 1: A 28-year-old woman presented with a two-week history of left foot drop. She frequently crossed her legs. Electrophysiology identified left fibular neuropathy with two compressive sites – at the fibular head and the anterior tarsal tunnel. She also displayed asymptomatic median neuropathy at the wrist. The remainder of the study did not show evidence of a generalised peripheral neuropathy, with normal conduction velocities elsewhere.

Case 2: A 64-year-old woman presents with a right foot drop post trivial trauma, in the setting of well-controlled Type 2 Diabetes. Electrophysiology exhibited peroneal neuropathy at the right fibular head, with incidental median neuropathy at the wrists. Additionally, her nerve conductions showed a generalised large fibre mixed peripheral neuropathy with slowed motor conduction in the intermediate range.

Conclusively, deletion in chromosome 17 p12 inclusive of PMP22 gene was identified in both cases confirming the diagnosis of HNPP.

Conclusion Whilst compressive neuropathies at common sites is frequently noted in HNPP, other electrophysiology parameters can vary considerably; from normal to generalized peripheral neuropathy/demyelination.

In cases with neuropathy following trivial trauma, multiple compressive neuropathies at common compressive sites, or at multiple sites along a single nerve, clinicians should maintain a high index of suspicion for diagnosis, even in older patients and with co-morbidities such as Diabetes.

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