CHALLENGING THE FLARE: CENTRAL AND PERIPHERAL NERVE BLOCK AS AN ACUTE INTERVENTION IN PEDIATRIC ERYTHROMELALGIA

E. Cavaglià, C. Donati, G. Liozzi, G. Fenocchio, P. Bruna, L. Moscaritolo | Interdisciplinary Center for the Diagnosis and Treatment of Complex Pediatric Pain, Regina Margherita Children's Hospital, Torino

Erythromelalgia (EM) is a rare and debilitating syndrome characterized by episodes of burning pain, erythema, and warmth, affecting the distal extremities. Attacks are precipitated by heat or exertion and relieved by cooling. EM may be classified as primary, most often linked to SCN9A mutations, or secondary to systemic conditions, mostly myeloproliferative diseases. The pathophysiology involves hyperexcitable nociceptive neurons and vasomotor dysregulation due to sympathetic hypoactivity. Diagnosis is clinical, based on the characteristic symptoms. Treatment remains challenging: there is no curative approach, and pharmacologic therapies yield inconsistent results. In particular, acute episodes resistant to conventional pain management demand alternative strategies. Despite the pathophysiological rationale, there is scarce literature addressing procedural interventions like central and peripheral nerve blocks (PNBs), especially in the pediatric population. Nerve blocks directly inhibit nociceptor transmission and can interrupt the pain-autonomic feedback loop contributing to symptom perpetuation. We present the case of a 17-year-old boy with first-onset primary EM, unresponsive to standard analgesia and adjuvant medications. His clinical course was marked by progressive, unremitting pain in all four limbs, associated with cutaneous hyperemia, edema over the course of forty days. Diagnostic investigations were unremarkable, and multiple therapeutic attempts failed, therefore he was subsequently referred to our center. The patient arrived to our attention in disabling conditions, unable to walk, with a significant degree of weight loss (10 kg), in profound psychological distress, including insomnia and anti-conservative ideation. He was already in therapy with tapentadol, gabapentin and mexiletine. Given the severity and refractoriness of symptoms, an early procedural approach was adopted. Bilateral upper limb PNBs (median, ulnar, radial nerves) with perineural catheter placement were performed, along with the insertion of an intradural catheter at L2–L3. Continuous infusion of levobupivacaine (0.25% for upper limbs, 0.125% for lower limbs) was initiated, accompanied by low-dose clonidine sedation giving immediate pain relief. Within 36 hours there was complete resolution of pain and dysautonomic symptoms (hyperemia and edema). A multimodal therapy was introduced, including fluoxetine, gabapentin, mexiletine, physiotherapy, and hypnosis. The patient was followed by an interdisciplinary team, including anesthesiologists, pediatricians, nurses, psychologists and psychomotricists. His recovery was gradual but consistent, with restoration of function within two weeks and by the third week he was discharged. This case underscores the potential role of peripheral nerve block as a safe and effective first-line intervention at the onset of EM in pediatric patients. When administered early, it may abort the vicious cycle of neurogenic inflammation, nociceptor sensitization, and psychological suffering. We advocate for further investigation and consensus on procedural pain control in EM to guide early and effective management strategies.