Recurrent Ipsilateral C5 Nerve Palsy Associated With Hereditary Neuropathy With Liability to Pressure Palsy

TL;DR

An 18-year-old man with a history of neck surgery developed recurring C5 nerve palsy, which was later linked to a rare genetic disorder called HNPP.

Contribution

This case highlights a rare presentation of HNPP with recurrent ipsilateral C5 nerve palsy, diagnosed through genetic testing.

Findings

The patient's C5 nerve palsy was linked to a deletion in the PMP22 gene, confirming HNPP.

Avoiding risky postures prevented further episodes of weakness after diagnosis.

No structural lesions were found around the C5 nerve root using imaging techniques.

Abstract

Hereditary neuropathy with liability to pressure palsy (HNPP) is an autosomal dominant disorder caused by heteroplasmic deletion of the peripheral myelin protein 22 (PMP22) gene. HNPP typically presents with clinical features such as peroneal nerve palsy or cubital tunnel syndrome, which are caused by mechanical compression. Diagnosing cases where neuropathy is absent at the pressure site can be challenging. This is a case study of an 18-year-old man who underwent surgery on the left side of his neck over 10 years ago to remove lymphadenopathy. Following the surgery, he experienced recurrent weakness but only sought medical attention when muscle weakness persisted for longer than a week postoperatively. Upon admission, the patient exhibited neurological symptoms consistent with C5 neuropathy, mainly affecting the deltoid muscles. No serological abnormalities were found to be associated with neuropathy. Neither magnetic resonance imaging nor computed tomography scans detected any lesions around the C5 nerve root. The posture during sleep was believed to cause excessive extension of the C5 nerve root, leading to the assumption that there was some vulnerability in the nerve. A transient sensory loss in the area innervated by the ulnar nerve prompted us to examine the fluorescence in situ hybridization study on the blood sample, which revealed a deletion of the PMP22 gene. The patient was diagnosed with HNPP and was advised to avoid risky postures. Following the implementation of these lifestyle changes, he did not experience any further weakness in his shoulders.

Figures