Topical phenytoin in a case of severe fibromyalgia: ex juvantibus proof for fibromyalgia as a localized non-length dependent small fiber neuropathy

We present a case of a 52-year old woman suffering from severe fibromyalgia, unable to manage even the lightest of housework, she gradually became crippled and her life became a ‘couch potato’ in patient’s own words. Treatment with topical phenytoin (5% titrated up to 15%) transformed her life, pain nearly vanished, and she became active, looking for a job, doing housework and she can walk rapidly. One explanation of this phenomenon could be that a number of patients suffering from fibromyalgia and having tender points suffer from localized length non-dependent small fiber neuropathy, and this pathology can be found in the skin above the tender points.