DERMATOME-ORIENTED PENS IN LONG-STANDING THORACIC POSTHERPETIC NEURALGIA: A CASE REPORT

G. Di Giuseppe¹, I. Olivieri¹, C. Angeletti² | ¹Dip.to Anestesia, Terapia intensiva e Terapia del dolore, Ospedale Mazzini, Teramo, Italy; ²L'Aquila, Italy

Background. Postherpetic neuralgia (PHN) is one of the most disabling chronic neuropathic pain syndromes, particularly among older adults. Despite pharmacologic treatment, many patients continue to experience persistent pain, allodynia, sleep disturbances, and impairment of daily activities. Evidence supporting percutaneous electrical nerve stimulation (PENS) for thoracic PHN remains limited and largely extrapolated from studies of localized neuropathic pain and peripheral neuromodulation.
Case Presentation. An 86-year-old woman presented with refractory left thoracic PHN that had persisted for approximately four years. Ongoing treatment included transdermal buprenorphine and duloxetine 60 mg/day, with paracetamol/codeine used as rescue medication. Clinical assessment revealed mechanical allodynia, paresthesias, dysesthesias, sleep disturbance, and difficulty tolerating clothing contact in the affected submammary region. Dermatome-oriented PENS was performed with a 10-cm needle electrode. To cover the symptomatic area, two consecutive treatment fields were targeted (left flank and left submammary region), each stimulated for 25 minutes. Treatment parameters included a frequency of 100 Hz and a pulse width of 0.20 ms. The procedure was well tolerated, with no local irritation or adverse events. Immediately after treatment, pain intensity decreased to NRS 2/10, with a subjective reduction in mechanical allodynia.
Results. At 30-day follow-up, complete pain resolution had not occurred. However, the patient reported a clinically meaningful reduction in symptom burden. Pain was described as “softer”; flares were less frequent and less intense; rescue analgesic use had decreased; and sleep quality had partially improved. Clothing-related discomfort persisted but was less severe than before treatment. Symptom evolution followed a fluctuating, non-linear trajectory, with alternating periods of improvement and transient exacerbations.
Conclusions. In this elderly patient with long-standing, refractory thoracic PHN, dermatome-targeted PENS was feasible and safe, and was associated with meaningful modulation of neuropathic symptoms. Although the clinical response was not linear and complete pain resolution was not achieved, reductions in flare burden, rescue medication use, and functional interference suggest that symptom modulation may be a more realistic therapeutic objective than pain elimination in chronic PHN. This case also raises the hypothesis that repeated treatment sessions may be required to consolidate clinical benefit in patients with long-standing neuropathic pain.