Hereditary neuropathy with liability to pressure palsies in a toddler

Tibial neuropathy, a rare manifestation of hereditary neuropathy with liability to pressure palsy: A case report

Hereditary neuropathy with liability to pressure palsy (HNPP) is characterized by acute, painless and recurrent mononeuropathies. Genetic testing shows PMP22 gene deletion of chromosome 17p11.2 can provide evidence for the diagnosis of HNPP. Reports on tibial neuropathy as the main manifestation of HNPP are very rare. We report a 14-year-old girl who was admitted to our hospital due to plantar foot numbness and plantar flexion weakness of her left foot. The patient had a history of lateral dorsal numbness and right foot drop when she was 3 years old. Clinical symptoms, and neurological examination demonstrated tibial neuropathy. Electromyography showed extensive peripheral nerve, including median nerve, ulnar nerve, tibial nerve and peroneal nerve, were involved. The diagnosis of HNPP was confirmed by genetic testing which disclosed a deletion of PMP22 gene. She was completely asymptomatic in one month after neurotrophic drug treatments.

Hereditary neuropathy with liability to pressure palsies

Hereditary neuropathy with liability to pressure palsies (HNPP) is characterized by recurrent sensory and motor neuropathy in individual nerves starting in adolescence or young adulthood, focal conduction abnormalities at entrapment sites on nerve conduction studies, and sausage-like swellings (tomacula) of the myelin sheaths by nerve biopsy. It is characterized genetically by the deletion of the chromosome 17p11.2-p12 region including the peripheral myelin protein-22 gene in the overwhelming majority of cases. HNPP may be frequently underdiagnosed or misdiagnosed owing to the heterogeneity of clinical and electrophysiological appearance. The main objective of this review is to describe clinical manifestations, paraclinical features such as electrodiagnostic, pathological, radiological and genetics findings, and possible treatments.

Hereditary neuropathy with liability to pressure palsy (HNPP): report of a family with a new point mutation in PMP22 gene

Background

Hereditary neuropathy with liability to pressure palsy (HNPP) is an autosomal dominant disorder most commonly presenting with acute-onset, non-painful focal sensory and motor mononeuropathy. Approximately 80% of patients carry a 1.5 Mb deletion of chromosome 17p11.2 involving the peripheral myelin protein 22 gene (PMP22), the same duplicated in Charcot-Marie-Tooth 1A patients. In a small proportion of patients the disease is caused by PMP22 point mutations.

Case presentation

We report on a familial case harbouring a new point mutation in the PMP22 gene.

The proband is a 4-years-old girl with acute onset of focal numbness and weakness in her right hand. Electroneurography demonstrated transient sensory and motor radial nerves involvement. In her father, reporting chronic symptoms (cramps and exercise-induced myalgia), we uncovered mild atrophy and areflexia on clinical examination and a mixed (predominantly demyelinating) polyneuropathy with sensory-motor involvement on electrophysiological study.

Both carried a nucleotidic substitution c.178 + 2 T > C on intron 3 of the PMP22 gene, involving the splicing donor site, not reported on databases but predicted to be likely pathogenic.

Conclusions

We described a previously unreported point mutation in PMP22 gene, which led to the development of a HNPP phenotype in a child and her father. In children evaluated for a sensory and motor transient episode, HNPP disorder due to PMP22 mutations should be suspected. Clinical and electrophysiological studies should be extended to all family members even in the absence of previous episodes suggestive for HNPP.

Hereditary neuropathy with liability to pressure palsies in childhood: Case series and literature update

Hereditary Neuropathy with Liability to Pressure Palsy (HNPP) is a rare condition in childhood with a diverse range of clinical presentations. We analyzed the clinical presentation and electrophysiological data of 12 children with a confirmed PMP22 gene deletion and reviewed the published reports of HNPP in children and compared our data with the reports from the literature review. Peroneal palsy was the most common presentation (42%) followed by brachial plexus palsy in 25% of our cases. Nerve conduction studies were always suggestive of the diagnosis demonstrating 3 major patterns: multifocal demyelination at the area of entrapment, generalized sensory-motor polyneuropathy and a combination of the two first patterns in a vast majority (60%). Surprisingly, there was bilateral or unilateral electrophysiological entrapment of the median nerve at the carpal tunnel in all our patients. The clinical presentation of HNPP in childhood is heterogeneous and electrophysiological findings are helpful in establishing the diagnosis. Any unexplained mononeuropathy or multifocal neuropathy should lead to PMP22 gene testing to look for the deletion. Early diagnosis is important in order to facilitate appropriate genetic counseling and also for the appropriate care for these patients.

Hereditary neuropathy with liability to pressure palsies and anaesthesia: peri-operative nerve injury

A 43-year-old female with carcinoma of the left breast underwent wide local excision of the tumour and sentinel lymph node biopsy under general anaesthesia. Three lymph nodes were removed uneventfully during the operation. Postoperatively, the patient complained of weakness and decreased sensation of her left arm. A diagnosis of peri-operative neuropraxia was made. This resolved completely over the following 4 weeks. Genetic testing confirmed a diagnosis of hereditary neuropathy with liability to pressure palsies.

Hereditary neuropathy with liability to pressure palsies (HNPP) in a toddler presenting with toe-walking, pain and stiffness

The typical clinical presentation of hereditary neuropathy with liability to pressure palsies is an adult-onset recurrent, painless monoparesis. Electrophysiological abnormalities--decreased nerve conduction velocities and delayed distal latencies--can be detected even in asymptomatic patients. We describe a toddler, who presented with asymmetric toe walking, painful cramps and stiffness in the legs. He had calf hypertrophy, brisk tendon reflexes and bilateral Babinski signs and the electrophysiological examination was normal. The unlikely diagnosis of hereditary neuropathy with liability to pressure palsies was reached 5 years later, when the boy started to complain of episodic numbness and weakness in the upper extremities. His father, paternal aunt and grandmother had similar symptoms, but they had never been investigated. The typical 1.5 Mb deletion on chromosome 17p11.2-12 was found in our patient and his affected relatives.