The Role of the Nervous System in the Pathophysiology of Psoriasis: A Review of Cases of Psoriasis Remission or Improvement Following Denervation Injury.

As most efforts in the last decade have focused on the immunologic basis of inflammatory skin disease, there has been less emphasis on the role of the nervous system in the disease process of psoriasis. Evidence in support of the neurocutaneous pathway has come from observations of patients experiencing unilateral improvement and even complete remission following nerve damage in the affected dermatomal region. The aim of this review was to investigate the role of neuropeptides in the intricate pathophysiology of psoriasis. The PubMed database was searched for individual case reports or case series that reported clearance or significant improvement in psoriatic disease in patients following documented nerve injury. A total of 11 cases were found that reported improvement of psoriatic lesions in areas afflicted by central or peripheral nerve injury. The most common causes of denervation were inadvertent surgical interruption, cerebrovascular accident, and poliomyelitis. In four cases the patients eventually regained neurologic function, which was associated with a recurrence of skin lesions. In cases of permanent nerve damage, there was remission of psoriasis. The cases reported in the literature to date provide clinical evidence that absence of neural input leads to psoriasis improvement, suggesting a crucial role of the nervous system in the pathophysiology of psoriatic disease. In fact, neuropeptides such as nerve growth factor, substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide may be important contributors of psoriatic disease and potential targets for future therapies.