Phenytoin Cream for the Treatment of Sciatic Pain: Clinical Effects and Theoretical Considerations: Case Report

Abstract

Chronic sciatic pain is difficult to treat. Patients often suffer from considerable pain and are severely hampered in their everyday activities. Most pharmacologic analgesic treatments have disappointing effects, and often are limited due to adverse events. New treatments are therefore needed. Surprisingly we found fast pain reduction after applying topical phenytoin cream at the painful dermatome in a 55-year-old patient suffering from sciatic pain due to pathology of a disc. This patient was treatment resistant for 13 years. Prescribing topical analgesic cream seemed to us at first sight quite counter-intuitive. The clear response in a treatment-resistant patient however provoked us to look deeper in the pathophysiology of sciatic nerve impingement. Recently it has been documented that proximal nerve lesions are followed by small fiber pathology in the skin. This might be a responsible peripheral wind-up generator for the chronification of pain in sciatic nerve compression. Topical application of the broad-acting voltage-gated sodium channel blocker phenytoin could reduce neuropathic pain in our case completely, supporting a peripheral mechanism of action for phenytoin cream in sciatic pain.

Keywords:

• sciatica
• topical
• phenytoin
• treatment
• neuropathic pain
• sensitization

Acknowledgement

We appreciate the lively librarian help of Janice Thomson.

Declaration of interest

DJK and JMKH are holders of two patents: (1) topical phenytoin for use in the treatment of peripheral neuropathic pain and (2) topical pharmaceutical composition containing phenytoin and a (co-)analgesic for the treatment of chronic pain.