Introduction: Stiff person syndrome (SPS) is a progressive neurological disorder characterized by fluctuating stiffness and rigidity in both axial and limb muscles. Stiff leg syndrome, an SPS variant mainly affecting limb muscles, is emerging as a distinct identity. The cause of SPS is unknown but an autoimmune pathogenesis is suspected. There are a few reported cases of hypopituitarism presenting with features suggestive of SPS.
Case: A 66-year-old woman presented to the neurologists with a 12-month history of gradually worsening back pain, leg spasms resulting in muscle stiffness and difficulty mobilising. Physical examination showed lower limb rigidity but normal sensorimotor function and reflexes.
MR brain scan showed minimal pituitary enlargement without any focal abnormality. Endocrine assessment revealed GH, TSH, gonadotropin and partial ACTH deficiency. Electromyography and anti-GAD antibodies were negative, but her presentation was felt to be consistent with SPS. Despite a favourable initial response to GABA-enhancing drugs, a lasting clinical remission was only achieved with hydrocortisone replacement therapy.
Discussion: We report this unusual case of hypopituitarism presenting in a patient with clinical features suggestive of SPS. Appropriate endocrine evaluation and pituitary hormone replacement may alleviate the significant morbidity associated with this condition.