Objective: To describe a case of painful legs and movement toes successfully treated with topical capsaicin.

Background: A 77yo man with depression and dyslipidaemia complained of involuntary movements in right toes started 4 years ago. In the past two years he also presented an aching and burning pain in the distal 1/3 of legs, worsened by movement. There was a slight broad-based walking associated to the pain and mild distal feet hypopalestesis. The toes exhibited involuntary serpentine movements, partially supressed by will (Video 1). There was no paresis. He was taking gabapentin 1200mg/day, lithium 600mg/day, escitalopram 20mg/day and clonazepam 2mg/day with poor response. The neuroaxis MRI was normal as well as the screening for polyneuropathies’s aetiology. The electromyography showed involuntary activation in extensor digitorum brevis, abductor hallucis, dorsal interossei and flexor hallucis longus in the right leg. Botulinum toxin injections where useful to reduce the movements but not the pain. Acupuncture was also ineffective. A trial with carbamazepine was interrupted by drowsiness. Amitriptyline 75mg/day showed good response but was withdrawn because of weight gain (10kg/ 2months). Topic lidocaine 5% had no therapeutic effect.

Methods: Topic capsaicin 0,025% was associated to lidocaine 5% and increased to 0,075% tid.

Results: After three months the pain was suppressed but not the movements. In the following months the pain appeared intermittently and was strictly related to depressive symptoms.

Conclusions: Spinella first described the Painful Legs and Moving Toes (PLMT) syndrome in 1971. Since then, numerous case reports and case series have demonstrated this illness main symptoms, electromyographic and semiological findings. However, a satisfactory control of the pain, movement control or both is usually hardly achieved despite the multiplicity of proposed treatments. The capsaicin binds to the vanilloid receptor subtype 1 and is used in chronic pain and neuropathies since the 80s. Two recent reviews from Cochrane about the efficacy of capsaicin in neuropathic pain showed a modest and partial outcome for low concentrations (up to 0,075%) but a good treatment response to very high concentrations (8%). As far as we know this is the first report of a successful treatment of neuropathic pain in PLMT syndrome with capsaicin.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/painful-legs-and-moving-toes-plmt-treatment-with-topic-capsaicin-a-case-report/