A case of stiff-person syndrome due to secondary adrenal insufficiency.

We report a case of flexion contractures in a patient's legs secondary to postpartum hypopituitarism. A 56-year-old woman presented with a 3-year history of worsening flexion contractures of the hips and knees. On admission, her hips and knees could not be extended, and she had muscle stiffness and tenderness to palpation of the lower extremities. We first suspected stiff-person syndrome or Isaacs' syndrome because of her muscle stiffness. However, multiple hormones did not respond to stimulation tests, and an MRI of the brain showed atrophy of the pituitary gland with an empty sella. A subsequent interview revealed that she had suffered a severe hemorrhage while delivering her third child. She was diagnosed with panhypopituitarism and started on cortisol replacement therapy. After 1 week of treatment with hydrocortisone (10 mg/day), her symptoms quickly improved. We then added 75 μg/day of thyroid hormone. During the course of her treatment, autoantibodies against VGKC complex were found to be weakly positive. However, we considered the antibodies to be unrelated to her disease, because her symptoms improved markedly with low-dose steroid treatment. There are a few reports describing flexion contractures of the legs in patients with primary and secondary adrenal insufficiency. As these symptoms are similar to those seen in stiff-person syndrome, adrenal and pituitary insufficiency should be taken into account to achieve the correct diagnosis and treatment in patients with flexion contractures and muscle stiffness.