Considerable Variability in the Efficacy of 8% Capsaicin Topical Patches in the Treatment of Chronic Pruritus in 3 Patients with Notalgia Paresthetica

Abstract

Notalgia paresthetica (NP) is a focal neuropathic itch condition manifesting in intense chronic or recurrent episodic itch in a hyperpigmented, macular, uni- or bilateral skin area located below and/or medially to the scapulae. Achieving satisfactory relieve in NP patients is challenging. In this case-series three female NP patients were treated with 8% capsaicin patches following a spatial quantification of their alloknetic area with a von Frey filament. The use of a von Frey filament in order to delimit the precise area of itch sensitization and thus patch application, proved clinically feasible. Although 8% topical capsaicin relieved itch in all three patients, the duration of the effectiveness varied greatly from only 3 days to >2 months. The treatment was well tolerated in the patients and there appear to be no significant hindrances to applying this treatment with NP as an indication, although it may only exhibit satisfactory effectiveness in certain patients. Placebo-controlled double-blinded trials are needed to confirm the effectiveness of the treatment and assess predictive parameters of the treatment outcome.

Preclinical and human surrogate models of itch

“…Alloknesis is a dysaesthetic state, in which a non‐pruritic stimulus provokes pruritic sensations, while hyperknesis is a dysaesthetic state, in which normally pruritic stimulus provokes enhanced pruritic sensations . Both can be assessed in an experimental setting by brush (primarily alloknesis), von Frey or weighted non‐painful pinprick stimulation in the immediate and surrounding area of pruritogen application or in lesioned pruritic skin in patients . Alloknesis is a nuisance in patients suffering from chronic itch, for example AD, which warrants further investigations of the possible neuroplasticity involved.…”

Topical capsaicin 8% for the treatment of neuropathic itch conditions

“…These remaining options include topical local anaesthetics, doxepin, intracutaneous botulinum toxin and systemic gabapentin, all of which have shown moderate promise in case studies/series, as well as topical capsaicin 8%, which has recently been approved for the treatment of peripheral nondiabetic neuropathic pain. Capsaicin 8% treatment has arguably been shown to be the most effective approach by several independent case‐series/studies . Here, we summarize the pharmacodynamics, practical application and expected outcomes from treatment with capsaicin 8% patches (Qutenza ® ; Grünenthal GmbH, Achen, Germany) in patients with neuropathic itch.…”

“…The acute pain associated with the treatment differs substantially between patients . In those patients unable to tolerate capsaicin‐induced pain, it can be successfully alleviated by pretreatment with local anaesthetic cream (e.g.…”

“…In those patients unable to tolerate capsaicin‐induced pain, it can be successfully alleviated by pretreatment with local anaesthetic cream (e.g. EMLA ® ; AstraZeneca, Luton, Bedfordshire, UK) cream for 60 min under occlusion or tramadol 50 mg administered 30–45 min before capsaicin application and/or use of cooling ice packs during the treatment . Use of EMLA cream has been shown not to reduce the effectiveness of capsaicin treatment in patients with neuropathic pain …”

“…Capsaicin‐evoked pain exhibits spatial summation, and hence treating a larger area than necessary should be avoided. As itch sensation is characterized by low spatial resolution, locating and quantifying the itching area is not always a trivial task . It can be particularly difficult in cases of notalgia paraesthica without hyperpigmentation, or in PHI when located on the back (Fig.…”