Epidural nerve block helps treat psoriasis

Researchers from Shanghai Jiao Tong University have reported a novel approach to treating psoriasis, using an epidural nerve block with the local anaesthetic lidocaine. Their results have been published in the Journal of Investigative Dermatology.

Psoriasis is a chronic immune-mediated skin disorder, with the peripheral sensory nervous system taking an active part in its pathogenesis. Symptoms are patches of skin that are dry, red and covered in silver scales that usually appear on the elbows, knees, lower back and scalp. There is no cure, but a range of systemic and topical treatments can relieve symptoms and signs and improve the appearance of skin patches.

“Case studies have shown that psoriasis patients have experienced significant symptom relief after receiving epidural anaesthesia during surgery, suggesting a pivotal role of the nervous system in psoriasis pathogenesis,” said lead investigator Dr Honglin Wang. “Additionally, there is increasing evidence linking the neuroimmune connection to psoriasis and other skin diseases. These factors inspired us to explore the possibility of directly targeting the nervous system for psoriasis treatment and the detailed mechanism of neuroimmune crosstalk in psoriasis.”

The investigators conducted a proof-of-concept study using an epidural injection of lidocaine to treat four patients with psoriasis. An epidural catheter was inserted between T12 (ie, the 12th thoracic vertebra) and L1 (the first lumbar vertebra) of the spinal cord. Lidocaine solution was injected through the catheter. Each patient received three or four treatments in total. Two patients had psoriatic lesions throughout the whole body; two patients had psoriatic lesions mainly distributed on the legs.

By the end of the study period, all patients achieved improvements in almost all lesions, showing a 35–70% reduction in Psoriasis Area and Severity Index (PASI) scores. Furthermore, skin improvements were maintained for at least 24 weeks after discontinuation of lidocaine treatment and no adverse effects occurred. The research is said to provide the first clinical evidence that sensory nerves are potential targets for psoriasis treatment.

To evaluate the neuroimmune communication signalling in psoriasis and the mechanism for lidocaine therapy, investigators also conducted a number of experiments on rats in which a psoriasis-like skin inflammation had been induced. They found that lidocaine acts on sensory neurons by downregulating disordered neurite growth and pro-inflammatory CGRP (calcium gene-related peptide) release. Concomitantly, restricted CGRP+ nerve density leads to reduced IL-23 production from dentritic cells, which express excessive CGRP receptors.

The proof-of-concept pilot study thus highlights the potential for epidural lidocaine injection as an effective and safe therapeutic strategy for psoriasis treatment — particularly for patients who respond poorly to the current treatment modalities — and expands understanding of the role of the peripheral nerve system in psoriasis and possibly other skin diseases. Manipulating the neuroimmune interplay puts a brake on neurogenic inflammation and downstream key inflammatory cytokine production, the researchers said, providing therapeutic prospects for sensory neuron‒orchestrated inflammatory skin diseases.

Co-investigator Dr Libo Sun acknowledged that the pilot study was small in scale and lacked a placebo-controlled arm and controls to prevent interference by environmental changes. The researchers hope to conduct large-scale clinical studies in future.

Image credit: iStock.com/ipopba

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