Introduction
Hereditary neuropathy with liability to pressure palsies (HNPP) is a peripheral neuropathy mostly caused by mutation of the PMP-22 gene that affects myelin development. It is characterized by motor weakness, sensory abnormalities, and muscle atrophy in the area in which neuropathy occurs. Winged scapula is a condition in which the medial border of the scapula protrudes from the thorax. Symptoms of HNPP can often occur with nerve entrapment, but patients with brachial plexus involvement are rare. We report on HNPP patient with winged scapula after military training.
Case report
A 19-year-old previously healthy male visited outpatient clinic due to muscle weakness in the right upper limb that occurred a month ago. The patient replied that he had never experienced an episode of muscle weakness or sensory abnormality. There was no family history of muscular dysfunction and he had no prescription medication. He joined the army three months ago and was serving as an artillery. There was no infection history in recent. In physical examination, he had right scapular winging and complained of a tingling sense at the trapezius site (Figure 1). The muscle power of the right shoulder and elbow was confirmed as Medical Research Council (MRC) grade 4 and the rest as grade 5. Deep tendon reflex was normal and no pathologic reflex. We suspected brachial plexus injury and performed electrodiagnostic study. The nerve conduction study showed abnormal findings in both median and ulnar nerves (Table 1). In needle EMG, the right supraspinatus and serratus muscles showed reinnervation pattern (Table 2). The bilateral F-wave test showed a delay in the median nerve (Table 1). In the MEP study, latency of both median nerves and tibial nerves was delayed. The patient was hospitalized to discriminate the upper motor lesion, and brain and C-spine MRI were taken, but showed normal findings. In the CSF, protein was slightly increased (51.7 mg/dL) and WBC was 0. Anti-ganglioside antibody test and genetic test were performed for suspected HNPP and AIDP. Anti-ganglioside antibody was negative and PMP-22 gene deletion was confirmed by genetic testing, and HNPP was diagnosed. The electrodiagnostic study followed up after 2 months showed mild improvement (Table 3).
Discussion
We initially suspected Parsonage-Turner syndrome because of muscle weakness with winged scapula at a young age and pain in the right trapezius. Considering clinical symptoms and military experience, HNPP was also suspected and finally diagnosed by genetic testing. If HNPP patients repeatedly use their arms, pressure is applied to the brachial plexus and it is thought that nerve damage may occur. Therefore, if a young patient with a lot of physical movements, such as a soldier, complains of muscle weakness on unilateral side, an electrodiagnostic study of bilateral sides must be performed, and the possibility of HNPP should be considered when abnormalities are observed in nerve conduction studies. |
