To examine the prevalence and patterns of electrodiagnostic abnormalities in multiple sclerosis (MS) patients in a predominantly Hispanic subpopulation in Miami, FL.

Peripheral nervous system abnormalities in MS have been reported in small case series. More recently, peripheral nerve lesions were visualized and quantified in MS by high-resolution magnetic resonance neurography. Little is known, however, about the prevalence of electrodiagnostic abnormalities including demyelinating neuropathies such as chronic inflammatory demyelinating polyradiculonauropathy (CIDP), axonal peripheral neuropathy and sympathetic dysfunction in the MS population.

This IRB-approved, observational, cross-sectional study examined the prevalence of electrodiagnostic abnormalities in MS patients. Electrodiagnostic data including nerve conduction studies, electromyography and sympathetic skin responses (SSR) were prospectively collected in 18 patients with MS. This study was offered to all-comers in the MS clinic over three months. Demographic data including age, sex, race/ethnicity was evaluated in addition to clinical features and MS-specific characteristics including MS subtype, duration of disease and duration of therapy.

Eighteen patients were studied but two patients were excluded from analysis due to lack of definite MS diagnosis. There were two males and 14 females. Ages ranged from 21 to 68 years (median=47 years). The median duration of disease was 8.9 years and median EDSS was 2.5. The frequency of electrophysiological axonal polyneuropathy (PN) was 75%, and 83% of these patients had clinical sensory symptoms thought to be secondary to MS. Four patients had diminished Achilles deep tendon reflexes, all of whom had axonal PN.  One patient had previously unrecognized CIDP. All 16 patients displayed prolonged SSRs consistent with autonomic dysfunction. Thirteen patients (81.3%) reported autonomic symptoms such as bladder abnormalities and blood pressure fluctuations.

There is a high prevalence of axonal polyneuropathy and autonomic dysfunction in MS patients that may have important clinical and therapeutic implications.