Painful diabetic peripheral neuropathy of the feet: integrating prescription-strength capsaicin into office procedures.

Prescription-strength (8%) capsaicin topical system is a US FDA-approved treatment for painful diabetic peripheral neuropathy of the feet. A 30 min application of the capsaicin 8% topical system can provide sustained (up to 3 months) local pain relief by desensitizing and reducing TRPV1-expressing cutaneous fibers. Capsaicin is not absorbed systemically; despite associated application-site discomfort, capsaicin 8% topical system is well tolerated, with no known drug interactions or contraindications, and could offer clinical advantages over oral options. Capsaicin 8% topical system are not for patient self-administration and require incorporation into office procedures, with the added benefit of treatment compliance. This article reviews existing literature and provides comprehensive, practical information regarding the integration of capsaicin 8% topical systems into office procedures.

Capsaicin 8% topical system is used to treat diabetic nerve pain of the feet. This in-office 30 min application can provide lasting relief of pain (for up to 3 months) by targeting the nerves damaged by diabetes. Since capsaicin acts at the site of diabetic nerve pain without being absorbed into the bloodstream, it is unlikely to interfere with other treatments and has few undesirable effects. Discomfort at the application site is the most commonly reported adverse event. Capsaicin 8% topical system must be applied by a healthcare professional and up to four topical systems can be used per treatment. Incorporating the use of capsaicin 8% topical systems into office procedures can help provide relief for patients living with diabetic nerve pain of the feet and may improve treatment compliance.

Central neuropathic itch from spinal-cord cavernous hemangioma: a human case, a possible animal model, and hypotheses about pathogenesis.

Cavernous hemangiomas (cavernomas) of the spinal cord are rare congenital malformations that comprise less than 5% of all intramedullary lesions. Despite this rarity, we describe the third case of central neuropathic itch associated with intramedullary cavernoma. Since fewer than 10 cases of central spinal itch from all causes have been published, this concurrence suggests the possibility of a specific association. A middle-aged man developed chronic disabling neuropathic itch and pain affecting his left shoulder and arm after frank hemorrhage of a midcervical cavernoma. We hypothesize that the relatively rostro-dorsal location of his lesion increased its likelihood of causing itch as well as pain. The microscopic pathology of cavernomas, specifically their gliotic rim containing hemosiderin-laden phagocytes, fosters ectopic firing of nearby neurons and makes cranial cavernomas highly epileptogenic. We hypothesize that these pathological features predispose cavernomas to cause central itch if they are located near, but spare, the central itch projection neurons in lamina I of the dorsal horn. Quisqualate injections into the deeper layers (neck) of the dorsal horns of rats produce pathologically similar lesions. Such rats develop unilateral dermatomal hyperalgesia and self-injurious scratching and biting (autotomy). Although this pathological grooming is currently interpreted as a response to chronic pain, we propose that it more likely models scratching provoked by central neuropathic itch, as seen in our patient and others. Study of quisqualate-injected rats may provide leads towards new treatments for neuropathic itch.