Evaluation of lower extremity mononeuropathy

Vasculitis

Can present as a mononeuropathy initially, but with time other nerves become involved, leading to a mononeuritis multiplex pattern. Although this is an uncommon cause of neuropathy, it should be considered when there are other symptoms or signs suggestive of vasculitis, such as fever, malaise, weight loss, and/or a vasculitic skin rash.[Figure caption and citation for the preceding image starts]: A purpuric rashFrom the collection of Loic Guillevin, MD, Hopital Cochin, Paris, France [Citation ends].Typically the onset of mononeuropathy is sudden and associated with severe neuropathic pain. Because vasculitis may progress rapidly, causing serious neurologic and systemic complications, it requires prompt recognition, diagnosis, and management. However, in the absence of a predisposing underlying disease such as SLE, vasculitis is often not recognized until the patient has developed a second mononeuropathy (mononeuritis multiplex).

Rarely, vasculitis involves only the peripheral nervous system, in which case no systemic symptoms and no serologic inflammatory markers occur. Although this diagnosis is obviously challenging, it is rare and needs to be considered only in cases of multiple mononeuropathies without other explanations.

Treatment comprises an initial course of corticosteroids plus an immunosuppressant. Drugs used to treat vasculitis depend on the severity of the clinical manifestations.