Submitted by: T. Darrell Thomas, MD
Edited by: Bryan DeSouza, MD
Jin P, Cheng L, Chen M, Zhou L. Low sensitivity of skin biopsy in diagnosing small fiber neuropathy in Chinese Americans. Journal of Clinical Neuromuscular Disease
Small fiber sensory neuropathy (SFSN) is a common entity seen in the NM clinic. Most often it is associated with diabetes but can be seen with a multitude of other conditions including other medical conditions, toxins, hereditary and immune mediated conditions. Many times patients are frustrated knowing they have neuropathic symptomatology but conventional EDX techniques are unrevealing. Frequently patients request confirmation of the diagnosis, and skin biopsy for intraepidermal nerve fiber density (IENFD) measurements is performed. In this article by Jin and associates, they described that nominative values for diagnosing SFSN differs in Chinese Americans versus other ethnic groups. In this study, a total of 23 Chinese Americans and 32 non-Chinese Americans were studied for the presence of small fiber neuropathy. The diagnostic sensitivity for IENFD was significantly lower in Chinese Americans (26.1%) compared to non-Chinese Americans (62.5%, p=0.01). IENFD was found to be significantly higher in Chinese Americans versus non-Chinese Americans. This has previously been reported in a healthy Thai population. They conclude that current nominative IENFD is influenced by ethnic differences in addition to sex and age.
This article adds additional insight in the evaluation of non-Caucasian patients with the diagnosis of small fiber neuropathy. When seeing a patient of different ethnicity, one must take into consideration that even if the test is normal, the patient can still have SFSN. This study is somewhat faulted in that the non-Chinese Americans included 78% Caucasian but other ethnic groups were included. It is possible that the diagnostic sensitivity in a pure Caucasian cohort would have been higher than 62.5%.