Can mild compression of the tibial nerve (nerve running down the lower back and leg) cause mild idiopathic pruritus (itching of unknown cause) in the absence of dermatological abnormalities?

From the Guidelines

Mild compression of the tibial nerve could potentially cause mild idiopathic pruritus without visible dermatological abnormalities in your patient. This phenomenon occurs because the tibial nerve contains sensory fibers that, when compressed, can generate abnormal sensory signals interpreted by the brain as itching, a concept supported by the British Association of Dermatologists' guidelines for the investigation and management of generalized pruritus in adults without an underlying dermatosis, 2018 1. Key points to consider include:

• Nerve fibre compression can cause pruritus in the corresponding dermatome, as noted in the guidelines 1
• Sensory symptoms including burning, paraesthesia, stinging, and tingling can accompany neuropathic pruritus, which may be relevant in diagnosing nerve compression-related pruritus 1
• Treatment options may include addressing any biomechanical issues with appropriate footwear or orthotics, physical therapy focusing on nerve gliding exercises, and medications such as gabapentin or pregabalin for neuropathic symptoms
• A short course of NSAIDs may help reduce inflammation around the nerve, and if conservative measures fail after 4-6 weeks, referral to neurology or consideration of a nerve block might be warranted

When evaluating the patient, consider performing a Tinel's test at the tarsal tunnel to assess for nerve irritation, as this can help confirm the presence of nerve compression. The connection between nerve compression and pruritus is based on the concept of neuropathic itch, where altered nerve signaling rather than skin pathology drives the itching sensation, as discussed in the British Journal of Dermatology guidelines 1.

From the Research

Neuropathic Itch and Tibial Nerve Compression

• Neuropathic itch can be caused by compression or degeneration of nerve fibers in the skin or extracutaneous in peripheral nerves or the central nervous system 2
• Localized neuropathic itch, such as brachioradial pruritus or notalgia paresthetica, can be due to a circumscribed nerve compression and are often limited to the corresponding dermatome 2
• Compression of the posterior tibial nerve can result in clinical findings consisting of numbness, burning, and painful paresthesia in the heel, medial ankle, and plantar surface of the foot 3

Tibial Nerve Compression and Pruritus

• There is no direct evidence to suggest that mild compression of the tibial nerve can cause mild idiopathic pruritis with no dermatological abnormalities
• However, neuropathic causes of chronic pruritus, including postherpetic neuralgia and notalgia paresthetica, are typically due to localized or generalized nerve dysregulation 4
• The tibial nerve can be compressed at multiple sites along its course, and detailed knowledge of the anatomy and anatomic variations is critical for proper diagnosis and treatment 5

Diagnosis and Treatment

• Diagnosis of posterior tarsal tunnel syndrome, which involves compression of the tibial nerve, can be made with the presence of a positive Tinel sign in combination with physical symptoms of pain and numbness along the plantar and medial surfaces of the foot 3
• Treatment for neuropathic pruritus can include topical neuropathic agents, such as menthol or pramoxine, as well as systemic oral or injectable treatments, such as gabapentin or antidepressants 4
• The Tibial Nerve Compression Test can be used as a screening tool for lumbar spinal canal stenosis, but its relevance to idiopathic pruritis is unclear 6