Stiff person syndrome (SPS), a basal ganglia disease? Striatal MRI lesions in a patient with SPS

Stiff person syndrome (SPS) is characterised by muscle rigidity and episodic spasms involving the axial and limb musculature. The hallmark is co-contraction of agonist and antagonist muscles, with continuous motor unit firing at rest. An autoimmune pathogenesis is based on the presence of anti-glutamic acid decarboxylase antibodies (anti-GAD, rate-limiting enzyme to synthesise γ-aminobutyric acid (GABA), in presynaptic GABAergic inhibitory synapses), and association with other autoimmune disorders and autoantibodies, and on response to immunotherapy. There is only a limited number of cases with brain MRI abnormalities. Our patient is the first reported case of SPS with MRI striatal abnormalities. A 69-year-old woman came in for consultation with an 18-month history of back pain, stiffness and progressive difficulty at walking. She had developed asymmetrical rigidity in her legs, with the left one being worse, from falls. In one of these falls she broke her left humerus. That limb remains useless, painful and rigid. She had progressive difficulty in turning over in bed and in getting up. In stressful situations and when trying to move, she had painful spasms in the left leg starting distally with toe and ankle extension, and progressing to knee and hip flexion while raising the leg from the bed. She became progressively bedridden. Her medical history was notable for diabetes mellitus (controlled with acarbose) and hypertension (controlled without drugs). …