Inherited focal, episodic neuropathies: hereditary neuropathy with liability to pressure palsies and hereditary neuralgic amyotrophy.

[neuralgic amyotrophy]

Hereditary neuropathy with liability to pressure palsies (HNPP ; also called tomaculous neuropathy ) is an autosomal-dominant disorder that produces a painless episodic , recurrent , focal demyelinating neuropathy . HNPP generally develops during adolescence , and may cause attacks of numbness , muscular weakness , and atrophy . Peroneal palsies , carpal tunnel syndrome , and other entrapment neuropathies may be frequent manifestations of HNPP . Motor and sensory nerve conduction velocities may be reduced in clinically affected patients , as well as in asymptomatic gene carriers . The histopathological changes observed in peripheral nerves of HNPP patients include segmental demyelination and tomaculous or "sausage-like " formations . Mild overlap of clinical features with Charcot-Marie -Tooth (CMT ) disease type 1 (CMT 1 ) may lead patients with HNPP to be misdiagnosed as having CMT 1 . HNPP and CMT 1 are both demyelinating neuropathies , however , their clinical , pathological , and electrophysiological features are quite distinct . HNPP is most frequently associated with a 1 .4 -Mb pair deletion on chromosome 17 p 12 . A duplication of the identical region leads to CMT 1 A . Both HNPP and CMT 1 A result from a dosage effect of the PMP 22 gene , which is contained within the deleted /duplicated region . This is reflected in reduced mRNA and protein levels in sural nerve biopsy samples from HNPP patients . Treatment for HNPP consists of preventative and symptom-easing measures . Hereditary neuralgic amyotrophy (HNA ; also called familial brachial plexus neuropathy ) is an autosomal-dominant disorder causing episodes of paralysis and muscle weakness initiated by severe pain . Individuals with HNA may suffer repeated episodes of intense pain , paralysis , and sensory disturbances in an affected limb . The onset of HNA is at birth or later in childhood with prognosis for recovery usually favorable ; however , persons with HNA may have permanent residual neurological dysfunction following attack (s ). Episodes are often triggered by infections , immunizations , the puerperium , and stress . Electrophysiological studies show normal or mildly prolonged motor nerve conduction velocities distal to the affected brachial plexus . Pathological studies have found axonal degeneration in nerves examined distal to the plexus abnormality . In some HNA pedigrees there are characteristic facial features , including hypotelorism . The prognosis for recovery of normal function of affected limbs in HNA is good , although recurrent episodes may cause residual deficits . HNA is genetically linked to chromosome 17 q 25 , where mutations in the septin-9 (SEPT 9 ) gene have been found .

Diseases
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Diseases presenting "also called familial brachial" symptom

neuralgic amyotrophy

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