Pitié-Salpêtrière Hospital

Pain Management in Erythromelalgia: A Systematic Review and Graded Appraisal Across Etiological Subtypes.

Erythromelalgia is a rare disorder characterised by burning pain, erythema and increased skin temperature in the extremities. Its pathophysiological heterogeneity, together with variable treatment responses, complicates management in the absence of evidence-based guidelines. This systematic review appraised pain-management strategies across reported aetiological subtypes. Following PRISMA 2020 guidelines, the review was registered in PROSPERO (CRD420251232074). PubMed, Embase, the Cochrane Library and ClinicalTrials.gov were searched for studies published or registered between 1 January 2000 and 30 April 2026. Randomised controlled trials, non-randomised interventional studies, cohort studies and case series were eligible; non-randomised studies required at least five individuals. Risk of bias was assessed using Joanna Briggs Institute tools and certainty of evidence using GRADE. Of 3372 records, 25 studies reporting 591 individuals were included. Aetiological subtype was reported for 277 individuals (46.9%). Mechanistic and aetiological characterisation varied substantially across domains, with haematological data available for 72.6% and SCN9A status for 19.0% of the overall population. Moderate-certainty evidence supported aspirin in myeloproliferative neoplasm-associated erythromelalgia. Low-certainty evidence suggested benefit from mexiletine and carbamazepine in primary erythromelalgia, as well as from prostaglandin analogues, corticosteroids, selected topical therapies and sympathetic interventions in specific contexts. Evidence for selective Naᵥ1.7 inhibitors and most other interventions was of very low certainty. Treatment-response patterns in better-characterised populations suggest that aetiology and underlying mechanisms may be relevant to treatment selection. However, this mechanism-informed approach remains hypothesis-generating and requires prospective validation through systematic aetiological and mechanistic characterisation. This systematic review provides a comprehensive, graded evaluation of the full spectrum of pain-management strategies in erythromelalgia, including systemic, topical, interventional and non-pharmacological approaches, across reported aetiological subtypes. Integrating risk-of-bias appraisal and GRADE certainty ratings, it identifies moderate-certainty evidence for aspirin in myeloproliferative neoplasm-associated disease and low-certainty evidence for conventional sodium-channel blockers in selected primary forms, while evidence for other interventions remains low or very low. These patterns suggest that aetiology may inform treatment selection, but require prospective validation.

Lidocaine-medicated plaster for treating acute autonomic and sensory neuropathy with erythromelalgia-like presentations.

[Congenital insensitivity to pain].

Congenital insensitivity to pain (CIP) is a rare syndrome with various clinical expressions, characterized by a dramatic impairment of pain perception since birth. In the 1980s, progress in nerve histopathology allowed to demonstrate that CIP was almost always a manifestation of hereditary sensory and autonomic neuropathies (HSAN) involving the small-calibre (A-delta and C) nerve fibres which normally transmit nociceptive inputs along sensory nerves. Identification of the genetic basis of several clinical subtypes has led to a better understanding of the mechanisms involved, emphasizing in particular the crucial role of nerve growth factor (NGF) in the development and survival of nociceptors. Recently, mutations of the gene coding for the sodium channel Nav1.7--a voltage-dependent sodium channel expressed preferentially on peripheral nociceptors and sympathetic ganglia--have been found to be the cause of CIP in patients showing a normal nerve biopsy. This radical impairment of nociception mirrors the hereditary pain syndromes associated with "gain of function" mutations of the same ion channel, such as familial erythromelalgia and paroxysmal extreme pain disorder. Future research with CIP patients may identify other proteins specifically involved in nociception, which might represent potential targets for chronic pain treatment. Moreover, this rare clinical syndrome offers the opportunity to address interesting neuropsychological issues, such as the role of pain experience in the construction of body image and in the empathic representation of others' pain.