A case report of hereditary neuropathy with liability to pressure palsies accompanied by type 2 diabetes mellitus and psoriasis

Literature review of clinical analysis of hereditary neuropathy with liability to pressure palsies

This review summarizes the clinical and electromyography (EMG) characteristics and peripheral myelin protein 22 (PMP22) gene-related diseases of hereditary neuropathy with liability to pressure palsies (HNPP). Clinical, EMG, and laboratory data of patients diagnosed with HNPP at our institution from 2022 to 2023 were retrospectively reviewed. Relevant literature from January 2003 to June 2024 was retrieved from PubMed using the keywords "hereditary neuropathy with liability to pressure palsies" and "HNPP." Clinical manifestations, EMG characteristics, and gene detection results of HNPP were summarized. All patients exhibited transient neurological symptoms and tested positive for the PMP22 deletion. EMG revealed multiple peripheral nerve abnormalities. Sixty-eight studies meeting the inclusion and exclusion criteria were included, comprising 124 HNPP cases (including six from our study), with 67 males and 57 females. The mean age of onset and diagnosis for the 124 cases were 26.5 ± 18 years and 32.7 ± 18.9 years, respectively, with a maximum onset-to-diagnosis interval of 40 years. Typical weakness and numbness in vulnerable areas were observed in 63.7% of cases, with 62% experiencing recurrent episodes. Atypical symptoms were present in 29.8%, while 6.5% were asymptomatic. Patients exhibited pain and muscular dystrophy (17.7%), pes cavus (12.1%), and a family history of HNPP (64.5%). Among symptomatic patients, triggers were traction or compression (57.8%), temperature changes (3.4%), or unclear (38.8%). Heterozygous PMP22 deletions and other PMP22 gene mutations were found in 77.4% and 22.6% of cases, respectively.

Multiple tendon transfer for a case of radial nerve palsy in hereditary neuropathy with liability to pressure palsy

Hereditary neuropathy with liability to pressure palsy (HNPP) is a rare autosomal dominant disease characterized by focal, recurrent, demyelinating peripheral neuropathies. It is caused by deletions of the gene encoding for peripheral myelin protein 22 (PMP22) on chromosome 17. While it may range widely, the most common clinical presentation is an acute, focal mononeuropathy with numbness or muscle weakness after trauma or compression. Diagnostic tools include electrophysiological studies, genetic tests and nerve biopsies. There is no standard surgical or pharmacological treatment. The course of the disease is usually benign, with spontaneous improvement after most episodes of peripheral nerve palsy. HNPP is best managed by early detection, preventative measures, and subsequent treatment of symptoms. According to the medical literature, operative treatment was undertaken in few cases and limited to decompression of the nerve at the classic entrapment sites of the carpal or cubital tunnels. We present a case of multiple tendon transfer (pronator teres to extensor carpi radialis brevis and flexor carpi radialis to extensor digitorum communis) with a two-year follow-up in a 24-year-old woman with HNPP who was affected by irreversible radial nerve palsy, and conclude with a review of the medical literature related to the disease.

A New Point Mutation in the PMP22 Gene in a Family Suffering From Atypical HNPP

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant inherited disorder commonly presenting with acute-onset, non-painful focal sensory and motor mono neuropathy. In 80% of cases, the genetic defect is a 1.5 Mb deletion on chromosome 17p11.2, including PMP22. Only few cases of partial deletion and point mutations in PMP22 are involved in HNPP. We investigated a 62-years-old man with lower limb plexopathy first considered as Garland’s syndrome. A month later, his 29 years old son also consulted for paresthesia on the peroneal nerve. Targeted sequencing of the PMP22 gene identified a c.370delT (p.Trp124Glyfs*31) in both affected patients. We report a new PMP22 point mutation associated with an atypical clinical phenotype of HNPP, a painful plexopathy of the lower limb worsenen by diabetes and a mere paresthesia, but a typical ENMG. This study illustrates the large spectrum of the disease, and emphasizes the importance of a complete ENMG and family history.

Peripheral neuropathy in diabetes: it's not always what it looks like

BACKGROUND

Hereditary Neuropathy with liability to Pressure Palsies (HNPP) is an autosomal dominant neuropathy, associated with deletion of the Peripheral Myelin Protein-22 (PMP-22) gene, causing recurrent painless palsies with age of onset between 10 and 30 years old. Only a few cases of Type 2 Diabetes and HNPP have been described and the coexistence of HNPP and Type 1 diabetes has never been reported.

CASE REPORT

A 54-year old man with a history of Type 1 diabetes, managed with continuous subcutaneous insulin infusion (CSII), presented with deterioration of long-standing motor and sensory symptoms, previously attributed to golfer's elbow, diabetic neuropathy and spinal degenerative disease. He had multilevel severe spine degenerative changes and L4/L5 and L5/S1 root impingements with a L4/L5 discectomy performed when he was 25 years old. On physical examination he had normal power and distal hypoaesthesia of the digits and plantar aspect of the feet. Investigations revealed normal full blood count, liver and renal function, electrolytes, vitamin B12 and serum folate. He suffered from primary hypothyroidism and thyroid function tests indicated adequate levothyroxine replacement. Nerve conduction studies revealed a generalized demyelinating sensorimotor neuropathy, with more severe involvement of nerves over entrapment sites. Further history that his father suffered from episodes of weakness and numbness was elicited. Genetic analysis revealed one copy of the PMP22 gene at 17p11.2 confirming the diagnosis of HNPP.

CONCLUSION

In people with diabetes the evaluation of peripheral neuropathy should include a careful history, a comprehensive physical examination, blood tests and in some cases nerve conduction studies and genetic testing.