[Cyclophosphamide-responsive subclinical Sjögren's syndrome in a patient with initial peripheral and central nervous system involvement].

A 36-year old woman was admitted because of painful dysesthesia of her extremities, suggesting the presence of mononeuritis multiplex. Laboratory data was almost within normal limits, with the exception of lupus anticoagulant positivity and increase of IgM level. We considered the possibility of connective tissue diseases and examined the patient accordingly. Keratoconjunctivitis sicca without dry eye symptoms, identified by rose-bengal and fluorescence testing, was the only recognizable abnormality. Oral sicca symptoms were not revealed although lip biopsy showed infiltration by a moderate number of plasma cells and lymphocytes. Under the diagnosis of subclinical Sjögren's syndrome, the following examination was carried out. Sural nerve biopsy specimens revealed wallerian degeneration and perivascular mononuclear cell infiltration of the vasa nervorum. We therefore concluded that the peripheral neuropathy was caused by subclinical Sjögren's syndrome. Magnetic resonance imaging (MRI) of the brain demonstrated multiple small lesions with increased spin echo images (T2 weighted) in the white matter. So, this patient was suffered from not only peripheral but also central nervous system complications. The mechanism of nervous system involvement was considered to be mononuclear cell-dependent ischemic damage caused by infiltration of the vasa nervorum. Both steroid pulse therapy and oral corticosteroid administration were ineffective in treatment of the peripheral neuropathy. Alternative use of cyclophosphamide (75 mg per day) was dramatically effective in relieving peripheral nervous system disorders. This was evident in the remarkable improvement of painful dysesthesia, grip strength and motor nerve conduction velocities. This case could be considered valuable for understanding the pathophysiology of Sjögren's syndrome and associated nervous system complications.