A Rare Genetic Disorder in the Differential Diagnosis of the Entrapment Neuropat

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J Clin Rheumatol. 2006 Apr;12(2):78-82.

(Note HNPP is the genetic opposite of CMT/HMSN)

A Rare Genetic Disorder in the Differential Diagnosis of the

Entrapment Neuropathies: Hereditary Neuropathy With Liability to

Pressure Palsies.

Koc F, Guzel R, Benliday IC, Yerdelen D, Guzel I, Sarca Y.

From the Departments of *Neurology, daggerMedicine and

Rehabilitation, and double daggerMedical Biology and Genetics,

Cukurova University School of Medicine, Adana, Turkey.

Hereditary neuropathy with liability to pressure palsies (HNPP) is an

autosomal-dominant, slowly progressive neuromuscular disorder, which

is characterized by recurrent acute peripheral nerve palsies.

Electrophysiological studies show decreased motor and sensory

conduction velocities in both clinically affected and unaffected

nerves. Focal thickening of myelin sheath with sausage-like

formation, also called tomacula, is seen in nerve biopsies. In

genetic studies, 1.5-Mb deletion on chromosome 17p11.2 is detected in

approximately 85% of HNPP cases and point mutations are determined in

some cases.We describe a 26-year-old man who had a 6-month history of

paresthesia in the little fingers of his hands. He was diagnosed with

HNPP by neurologic examination, and electrophysiological and

histopathologic studies. Studies in his mother and one brother also

showed entrapment neuropathy. However, no deletions or point

mutations were determined in this family. Other genetic defects apart

from the known ones might be present in this disease. The most

frequent entrapment syndrome, carpal tunnel syndrome, is also seen in

this disease, so physicians dealing with musculoskeletal problems

should be alert about this subject. Awareness of HNPP may help avoid

unnecessary operative interventions.