P.026 Acute lower limb spasticity: Stiff person syndrome responsive to immunomodulatory therapy in an adolescent female

Background: Stiff person syndrome (SPS) is a rare disorder presenting with progressive stiffness and spasms of the musculature of the trunk and limbs. SPS is reported very rarely in children and adolescents, with 5 cases over 25 years in a recent 99 patient cohort. Methods: Case Study Results: Herein we report a 15 year old female, presenting with acute onset of rapidly progressive spasticity of the lower extremities. Initial exam was remarkable for markedly limited left knee range of motion, in addition to asymmetrical knee spastic catch and hyper-reflexia. EMG revealed almost continuous motor unit activity which dissipated with voluntary muscle contraction. Diagnosis was confirmed by high titres of glutamate decarboxylase (GAD65) antibodies >25,000 units/ml. The patient was initially treated with IVIG, baclofen, and diazepam followed by IV methylprednisolone, with mild subjective improvements. One day following the first rituximab treatment, she achieved spontaneous knee flexion and regained the ability to ambulate independently. There is a residual spastic catch at the knees. Conclusions: This case highlights that SPS, albeit extremely rare, should be considered in the differential diagnosis of acquired spasticity in children. Also noteworthy is the relatively rapid resumption of function with aggressive immunomodulatory treatments in this historically devastating disorder.

Stiff-Person Syndrome Following Tick-Borne Meningoencephalitis

Stiff-person syndrome (SPS) is a rare disorder characterized by muscle stiffness and painful spasms. Misdiagnosis may occur due to the fact that the clinical picture of SPS is often atypical. The main pathophysiologic mechanism underlying the development of SPS is insufficient inhibition at the cortical and spinal levels. There is good evidence for a primary autoimmune etiology. A 61-year-old man was admitted to a neurological department due to muscle hypertonia with episodic attacks of painful spasms predominantly affecting axial muscles. The symptoms developed shortly after tickborne meningoencephalitis. Electromyography (EMG) revealed signs of continuous motor unit activity. Antibodies against glutamate decarboxylase (anti-GAD) were highly elevated. We present a case of a man who developed clinically severe anti-GAD positive SPS, provoked by tick-borne encephalitis. After therapeutic plasma exchange (TPE) a rapid, temporary improvement of the clinical and neurophysiological findings was noted. Only after being placed on long-term immunosuppression did the patient achieve stable recovery. This case supports the importance of EMG findings and demonstrates the effect of TPE as well as the need for chronic immunosuppression in severe cases of SPS.