Response to steroid treatment in anti–glutamic acid decarboxylase antibody-associated cerebellar ataxia, stiff person syndrome and polyendocrinopathy
✍ Scribed by Ji-Youn Kim; Eun Joo Chung; Jong-Hun Kim; Ki-Young Jung; Won Yong Lee
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 60 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0885-3185
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✦ Synopsis
Glutamic acid decarboxylase (GAD) is an enzyme that catalyzes the conversion of glutamate to ␥-aminobutyric acid (GABA). Anti-GAD antibody (GAD-Ab) is considered to be a marker for stiff person syndrome (SPS), 1 insulin-dependent diabetes mellitus (IDDM), and polyendocrine autoimmune syndrome. 2 Additionally, it has been reported in rare neurological diseases such as progressive cerebellar ataxia, 3 epilepsy, and myoclonus. 4 The presence of high titers of GAD-Ab and coexisting autoimmune diseases provide the rationale for using immune-modulating treatment in GAD-Ab-associated ataxia. However, response to treatment is still controversial. We report here a patient with progressive cerebellar ataxia, SPS, IDDM, Hashimoto thyroiditis, epilepsy, and GAD-Ab who responded to steroid treatment.
A 40-year-old woman was hospitalized with complaints of a 4-month history of progressive gait disturbance, painful stiff back, and limited joint motion on 22 May 2005. She was diagnosed with diabetes mellitus and Hashimoto thyroiditis in 2002. There was no familial history of ataxia or muscle spasm.
Neurologic examination showed an ataxic gait, bilateral limb dysmetria, and terminal tremor without ocular motor abnormality. The International Cooperative Ataxia Rating Scale (IC-ARS) score 5 was 31. Following a previous study, 6 the distribution of stiffness index was 3 and the heightened sensitivity score was 6.
There was no evidence of central nervous system infection or vitamin E and B12 deficiency. Cerebrospinal fluid (CSF) oligoclonal band was not detected. There were no antibodies against Hu, Yo, or Ri in either serum or CSF. Other autoimmune antibodies, including rheumatic factor, ANCA, FANA, anti-cardiolipin antibody, lupus anticoagulant antibody, antiplatelet antibody, and anti-ds DNA antibody were not detected. Genetic studies for spinocerebellar ataxia type 1, 2, 3, 6, 7, and 8 were negative. By radioimmunoassay, GAD 65 -Ab titers were elevated in serum (92,680 U/mL) and CSF (2,849 U/mL). CSF immunoglobulin G (IgG) index and IgG GAD-specific index were 0.61 (normal Ͻ 0.67) and 4.8 (higher than IgG index), respectively, indicating intrathecal synthesis of antibody-specific IgG. 1,7 Electrophysiologic study revealed continuous motor activity on paraspinal electromyographic examination with normal peripheral nerve conduction studies. Two months after 5-day intravenous methylprednisolone (1,000 mg/day) treatment, the ICARS score, distribution of stiffness index, and heightened sensitivity score were improved; serum GAD 65 -Ab