Objective:

To characterize the presentation of small fiber neuropathy (SFN) in people with multiple sclerosis (pwMS) who suffer from neuropathic pain and/or dysautonomia.

Background:

Pain and sensory symptoms are reported in up to 80% of pwMS, with prevalence of neuropathic pain at approximately 26%. Historically, pain in MS has been mostly attributed to central lesions. Some recent studies have begun to emerge investigating demyelinating, large fiber peripheral neuropathies in pwMS, however little has been done to investigate whether small, non-myelinated fibers are also affected in pwMS with neuropathic pain and autonomic symptoms.

Design/Methods:

A total of 28 pwMS and neuropathic pain and/or autonomic symptoms underwent skin punch biopsies for evaluation of SFN at a single center. Samples were collected from a proximal and distal site in the lower extremity and sent for evaluation of intra-epidermal and sweat gland nerve fiber density. Symptoms and severity were characterized through collection of responses to the MGH Small-Fiber Symptom Survey.

Results:

Of 28 pwMS tested, 18 had significantly reduced intra-epidermal or sweat gland nerve fiber density in at least one of the biopsied sites. 2 patients had low-normal values in at least one of the collected sites. 8 patients had normal nerve fiber densities. Of those who tested positive, 90% were female with a mean disease duration of 5 years. MGH SSS results showed total symptom severity scores ranging from 17 to 85.

Conclusions:

This small case series indicates small fiber neuropathy as a potential cause of neuropathic pain and dysautonomia in pwMS. Symptoms of SFN and dysautonomia have a wide range of manifestations in this population. A larger study population is needed to further characterize the true prevalence of SFN in pwMS with neuropathic pain and dysautonomia, and to investigate potential mechanisms.