Any reported cases of idiopathic small fiber neuropathy effecting women in their young 20's?

SFN: The prevalence of small fiber neuropathy is unknown. However, there are reported cases in the literature. Here is example: "Incidence and prevalence of small-fiber neuropathy. A survey in the Netherlands". Hope it helps.

Surely: There are cases like this, although they are not idiopathic. Some reports are for rare inherited causes of this condition, which are not routinely tested for in clinic. Are you certain of the diagnosis? This is not an easy diagnosis to make.