OTHER NMDs

Stiff-person syndrome (SPS) is a rare autoimmune neurological disorder characterized by a progressive axial and proximal limb stiffness and painful spasms. Reports of pediatric-onset SPS are scarce. We report and present the videos of a 10-year-old boy, born in Angola, with no relevant personal or family background. At seven years of age, he started having involuntary, painful, paroxysmal muscle contractions, lasting from a few minutes to half an hour, initially only in the legs, and later in the four limbs, masticatory muscles and neck, with progressive worsening and daily frequency. On examination, he presented muscle spasms triggered by sound. He had no associated stiffness or hyperlordosis and no other changes on the neurological examination. EMG findings were supportive of SPS with simultaneous and continuous firing of motor units at rest and co-contraction of agonist-antagonist muscles. Serology testing for anti-GAD65, anti-amphiphysin and anti-glycine antibodies, both in serum and cerebrospinal fluid, were negative. Phospho-calcium metabolism and ionic changes, as well as other associated diseases such as diabetes mellitus, thyroiditis or epilepsy, were excluded. The patient was initially treated with diazepam and baclofen but deteriorated with more frequent spasms and spreading to other body parts. After a single course of intravenous immunoglobulin there was marked improvement of symptoms. Currently, he is clinically stable after one year of follow-up, with rare and less severe symptoms, under symptomatic treatment only, with cyclobenzaprine and carbamazepine. SPS is a diagnostic challenge given its rareness. As in this case, SPS in pediatric age is typically seronegative and may have a presentation with more distal muscle involvement. Treatment is based on symptomatic control of spasms and immunomodulation of the disease with intravenous immunoglobulin, although there are no pediatric prospective studies.