Presence of Decreased Intraepidermal Nerve Fiber Density Consistent with Small Fiber Neuropathy in Patients with Central Post-Stroke Pain

Abstract

Dear Editor, In the United States, approximately 800,000 strokes occur annually, with 11%-55% of stroke survivors experiencing post-stroke pain [1–5]. Central post-stroke pain (CPSP) is recognized as a neuropathic condition often defined as being of thalamic origin, although extra-thalamic stroke can also result in CPSP [3,5–7]. The reported prevalence of CPSP is between 1% and 12% following all stroke, and up to 18% when sensory deficits are present [3,6,7]. Although the pathophysiology of CPSP remains incompletely understood, as the name implies, CPSP is most often associated with “central,” not peripheral nervous system abnormalities. Here we report four consecutive patients without prior evidence of a peripheral neuropathy, who developed CPSP following a stroke and in who further evaluation led to the documentation of skin biopsy findings consistent with small fiber neuropathy (SFN). Decreased peripheral intraepidermal nerve fiber density (IENF) is observed in many painful conditions associated with SFN including complex regional pain syndrome, diabetic neuropathy, chemotherapy-induced neuropathy, and hypothyroidism [8–15]. Similar skin biopsy findings have been recently reported in some, but not all, fibromyalgia patients leading some clinicians to consider the diagnosis of SFN in certain fibromyalgia patients. Although the precise role that the loss of small caliber (presumptive nociceptor) IENF plays in clinical pain symptoms is still unclear, their normal physiologic role in acute pain mechanisms is well-defined. Since the anatomy of the nociceptive/pain pathways (matrix) approximates a closed-loop system, coupled with the recognition that …