[The stiff-man syndrome with diabetes mellitus type 1 and autoimmune thyroiditis]

A 54-year-old woman with type 1 diabetes of about 2 years' duration developed painful cramps in the muscles of the abdominal wall, the back and the thighs. On admission physical examination confirmed markedly increased tone of the muscles of the trunk and those proximal to it.

Markedly increased amounts of anti-GAD (glutamic acid decarboxylase) antibodies were present in both serum and cerebrospinal fluid (CSF). Electroneurography and -myography revealed mild polyneuropathy but no other neurological abnormality.

Suspected stiff-man syndrome (SMS) was confirmed by the increased anti-GAD antibodies and the marked improvement on gradually increasing doses of clonazepam. The autoimmune syndrome affected several organ systems: central nervous system (SMS), pancreas (diabetes), thyroid (immuno-thyroiditis). Immunosuppressive treatment with azathioprine was begun. The patient remains in good general condition 22 months after the initial diagnosis, and there have been no new organ involvement.

It is important to include SMS in the differential diagnosis, even though the symptoms are not those of the full-blown picture of this rare disease. Absence of muscle cramps and myoclonus but presence of depressive symptoms can easily result in misdiagnosis, preventing early initiation of effective symptomatic treatment.