Small fiber neuropathy associated with hyperlipidemia: utility of cutaneous silent periods and autonomic tests.

G Morkavuk,A Leventoglu

doi:10.1155/2014/579242

Abstract

Background. Established electrophysiological methods have limited clinical utility in the diagnosis of small fiber neuropathy. The cutaneous silent period (CSP) may be useful as a method for the evaluation of smaller and unmyelinated fiber dysfunctions. Hyperlipidemia is a very rare cause of small fiber neuropathy. In this study, hyperlipidemia and small fiber neuropathy in symptomatic patients with normal nerve conduction studies were evaluated with autonomic tests and cutaneous silent periods. Methods. Twenty-five patients with clinically suspected small fiber neuropathy and 23 healthy volunteers were included. CSP latency and duration, as well as CSP latency difference of the upper and lower extremities, were examined. Two tests were used to assess the autonomic nervous system, namely, the R-R interval variation test in basal and profound breath conditions and the sympathetic skin response. Results. Twenty-five patients with clinically suspected small fiber neuropathy and normal nerve conduction studies were compared with 23 controls. In the upper extremities, patients had prolonged CSP latencies (P = 0.034) and shortened CSP durations (P = 0.039), whereas in the lower extremities, patients had shortened CSP durations (P = 0.001). The expiration-to-inspiration ratios were also reduced in patients groups. There was no significant difference between sympathetic skin response latencies and amplitude of the case and control groups. Conclusion. Our findings indicate that CSP may become a useful technique for the assessment of small fiber neuropathy in hyperlipidemic patients.

Highlights

Small fiber neuropathy (SFN) can be defined as generalized peripheral neuropathy, where small myelinated A-delta and unmyelinated C nerve fibers are more affected alone or compared with large fibers
Patients were excluded if they had a history of any specific peripheral nerve, muscle disease, neuromuscular junction disease, cervical spondylosis, spine surgery, central nervous system disease, including stroke, dementia, or medical conditions associated with peripheral neuropathy, such as DM, metabolic disorders, alcohol abuse, and malignancy
There was no significant difference in HDL-cholesterol and blood pressure between study and control group

Summary

Introduction

Small fiber neuropathy (SFN) can be defined as generalized peripheral neuropathy, where small myelinated A-delta and unmyelinated C nerve fibers are more affected alone or compared with large fibers. The methods for assessing small fiber dysfunction are limited despite its clinical significance. Their clinical use is limited, since most of these methods are invasive or time consuming or require special equipment. The cutaneous silent period (CSP) may be useful as a method for the evaluation of smaller and unmyelinated fiber dysfunctions. Hyperlipidemia and small fiber neuropathy in symptomatic patients with normal nerve conduction studies were evaluated with autonomic tests and cutaneous silent periods. Twenty-five patients with clinically suspected small fiber neuropathy and normal nerve conduction studies were compared with 23 controls. Our findings indicate that CSP may become a useful technique for the assessment of small fiber neuropathy in hyperlipidemic patients

Objectives

Methods

Results

Conclusion