[Stiff-person syndrome: a case report]

Stiff-person (stiff-man) syndrome is characterised by symptoms of muscular rigidity and spasms, which are generally of an axial nature. Involuntary contractions of the agonist and antagonist muscles caused by activity of the motor units during rest are the main clinical and electrophysiological marker of the disease. The nature of the syndrome is considered to be autoimmune, with positive glutamic acid decarboxylase (anti-GAD) antibodies in most patients. These antibodies exert an influence over GABAergic transmission.

A 29-year-old female who was admitted to hospital with a diagnosis of psychogenic mutism. While in hospital the patient developed a clinical picture consisting in generalised stiffness that was predominantly axial and proximal with hyperreflexia in the four limbs and strong contraction of the muscles of the abdomen. The most striking lab finding was the presence of anti-GAD, anti-parietal cells, anti-microsomal/TPO and antithyroglobulin antibodies, together with oligoclonal immunoglobulin G bands in the cerebrospinal fluid. Treatment was established with benzodiazepines, antispastic agents and corticosteroids, and the clinical symptoms progressively improved until they had partially remitted at two months. The lab findings and clinical features are compatible with stiff-person syndrome in a patient with associated psychiatric comorbidity.

Anti-GAD antibodies are not exclusive to stiff-person syndrome and can also be found in a number of other autoimmune disorders. Other mechanisms which can also produce a dysfunction of the GABAergic system have also been suggested. The syndrome can be difficult to diagnose from the clinical point of view and it must therefore be borne in mind in patients who begin with unexplainable stiffness and spasms because it is a potentially treatable pathology.