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Abstract Details

Humoral Immune Microvasculopathy: Treatable Motor-Sensory Axonal Polyneuropathies with C5b-9 Deposition on Endoneurial Microvessels
Neuromuscular and Clinical Neurophysiology (EMG)
P12 - Poster Session 12 (12:00 PM-1:00 PM)
1-002
To characterize clinical features and treatment responses of patients with motor-sensory polyneuropathies who had humoral immune microvasculopathy (HIM) with deposits of the terminal components of complement (C5b-9) on endoneurial microvessels.
C5b-9 deposition on endomysial capillaries is a characteristic feature of dermatomyositis.  We studied patients with motor-sensory polyneuropathies and C5b-9 deposition on endoneurial microvessels. 
Retrospective chart review of clinical, laboratory, electrodiagnostic and neuropathologic features of 16 consecutive adults with motor-sensory polyneuropathies and C5b-9 deposition on endoneurial microvessels detected on evaluation of nerve biopsies.  Strength was serially measured quantitatively using hand held dynamometry at the first clinic visit, pre-treatment, post-treatment and at follow-up clinic visit. High dose corticosteroids were used for treatment.

Clinical features included gradually progressive (mean duration of symptoms 3.5 years), asymmetric, distal predominant, weakness. Other features were ages of onset between 34 to 84 years (mean ± SD age, 64±12 years), male predominance (75%) and diabetes (56%).  Weakness was always present in distal legs and occurred in hands in 44%.  Sensory loss was distal and pan-modal.  Electrodiagnostic studies showed sensorimotor neuropathy (94%) with axon loss, but never demyelination. Muscle and nerve biopsies showed capillaries with C5b-9 deposition on endoneurial microvessels (94%) and/or endomysial (63%) capillaries.  All patients had axon loss, usually varied among or within fascicles.  All patients had rapid improvement in strength in the weeks after treatment, comparing their pre-treatment and post-treatment courses (p = 0.0007).

Patients with HIM motor-sensory polyneuropathy syndromes are frequently males over 60 years of age with progressive asymmetric, predominantly distal leg, and some hand, weakness. The predominant pathologic findings are axon loss with C5b–9 deposition on endoneurial microvessels. High dose corticosteroid treatment of HIM is associated with significant and rapid improvement in muscle strength. Controlled trials will be useful to test and validate these results.
Authors/Disclosures
Bhavesh Trikamji, MD (University of California Los Angeles)
PRESENTER 		Dr. Trikamji has nothing to disclose.
Alan Pestronk, MD, FÂ鶹´«Ã½Ó³»­ (Washington University in Saint Louis - Neurology) The institution of Dr. Pestronk has received research support from Jain. The institution of Dr. Pestronk has received research support from Fulcrum. The institution of Dr. Pestronk has received research support from Argenyx. The institution of Dr. Pestronk has received research support from NeuroNext.