Thymic Abnormalities and Stiff Person Syndrome

Abstract

SESSION TITLE: Global Case Report Poster - Cardiothoracic Surgery SESSION TYPE: Global Case Report Poster PRESENTED ON: Tuesday, October 25, 2016 at 01:30 PM - 02:30 PM INTRODUCTION: Stiff Person Syndrome (SPS) is a rare autoimmune neurological disorder characterized by painful muscle spasms and rigidity. It may be seen in association with other autoimmune diseases, and 60% of patients have anti-glutaminic acid decarboxylase (GAD) antibodies. There are limited reports of patients experiencing significant improvement of their symptoms following a thymectomy. We report on 2 patients with SPS who underwent thymectomies at our institution. CASE PRESENTATION: A 39-year-old lady presented with frequent falls associated with lower back pain and stiffness of her lower limbs which led to difficulties with ambulation. A diagnosis of SPS was made based on her symptoms, an electromyogram (EMG) showing continuous motor unit activity and elevated anti-glutamic acid decarboxylase (GAD) antibody levels. Computed tomography (CT) scan of the thorax revealed a large well-circumscribed mediastinal mass (Fig.1 and 2), which was confirmed to be a thymoma after percutaneous biopsy. She underwent surgical resection of the mass and histopathology revealed a Modified Masaoka Stage IIa type B1 thymoma. Post operatively, she made an uneventful recovery and was able to ambulate independently with a walking frame on discharge. Our second patient was a 54-year-old ophthalmologist who presented with intermittent episodes of myoclonic jerks of her trunk, worsened by stress and auditory or tactile stimuli with elevated anti-GAD antibody levels. CT thorax revealed a hyperdense heterogeneity in the anterior superior mediastinal region. She underwent surgery and histopathology showed thymic tissue with reactive lymphoid hyperplasia. Her symptoms improved post-operatively and she was able to resume work. DISCUSSION: SPS associated with thymic abnormalities occurs more frequently in females (66%), and mean age of diagnosis was 55 years. Currently, there are 7 reported cases worldwide of SPS associated with thymoma, with patients reporting a significant improvement of symptoms following thymectomy. Most were World Health Organisation (WHO) type B1/B2 thymomas, with one AB and one invasive carcinoma. Five of the 7 cases had elevated anti-GAD antibody levels, which dropped significantly post-thymectomy. Symptom recurrence occurred spontaneously or following tactile stimuli in 3 of these cases. This was successfully controlled with pyridostigmine, intravenous immunoglobulin (IVIG) or plasmapheresis. All patients remained symptom free on long term follow up. CONCLUSIONS: In conclusion, limited reports suggest that thymectomy can be effective for relieving symptoms of SPS and should be strongly considered when thymomas are discovered in association with this condition. However, all patients should be counselled that symptoms may recur in future and thus remain on long-term follow up with a neurologist. Reference #1: Solimena M, Folli F, Denis-Donini S, Comi GC, Pozza G, De Camilli P, Vicari AM: Autoantibodies to glutamic acid decarboxylase in a patient with stiff-man syndrome, epilepsy, and type I diabetes mellitus. N England J Med. 1988, 318:1012-20. 10.1056/NEJM198804213181602 Reference #2: Gershanik OS: Stiff-person syndrome. Parkinsonism Relat Disord. 2009, 15:S130-S134. 10.1016/S1353-8020(09)70799-0 DISCLOSURE: The following authors have nothing to disclose: Rachel Chen Yanlin, Tousif Kabir, Atasha Asmat, Dokev Basheer Ahmed Aneez No Product/Research Disclosure Information