Division of Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, Houston.
Clinical Molecular Diagnostic Laboratory, Duke University Health System, Durham, North Carolina.
JAMA Neurol. 2014 Jun;71(6):782-4. doi: 10.1001/jamaneurol.2013.5083.
Isolated sulfite oxidase deficiency (ISOD) causes severe intellectual disability, epilepsy, and shortened life expectancy. Intractable seizures are invariable in children with ISOD; however, to our knowledge, infantile spasms with a corresponding hypsarrhythmia pattern on electroencephalogram have never been reported. In addition, the nonepileptic paroxysmal movement disorder hyperekplexia has not previously been reported with ISOD.
We describe an infant with ISOD who initially presented with neonatal seizures, diffusion restriction noted on magnetic resonance imaging, and elevated serum S-sulfocysteine consistent with ISOD. A homozygous mutation in the SUOX gene was identified, confirming the diagnosis. Uniquely, this patient developed a profound accentuated startle response that did not have a corresponding electrographic change on electroencephalogram consistent with hyperekplexia. This was followed by a change in the child's electroencephalogram to the chaotic pattern of hypsarrhythmia and brief tonic seizures with attenuation of the hypsarrhythmia pattern characteristic of infantile spasms.
The evolution of seizures associated with ISOD is poorly characterized because of the small number of patients. We report what we believe to be the first case of a child with ISOD who developed infantile spasms and hyperekplexia. This expands the phenotypes associated with ISOD and also should caution clinicians to not assume that all abnormal movements are seizures.
孤立型亚硫酸盐氧化酶缺乏症（ISOD）可导致严重的智力障碍、癫痫和预期寿命缩短。患有 ISOD 的儿童通常会出现难治性癫痫发作；然而，据我们所知，从未有过与之对应的脑电图出现高度失律模式的婴儿痉挛症的报道。此外，与 ISOD 相关的非癫痫性阵发性运动障碍——强肌张反射也从未有过报道。
我们描述了一例 ISOD 婴儿，最初表现为新生儿癫痫发作、磁共振成像上显示弥散受限和血清 S-亚磺基半胱氨酸升高，与 ISOD 一致。在 SUOX 基因中发现了纯合突变，确诊了该疾病。该患者出现了一种明显的增强性惊吓反应，这与强肌张反射一致，但其脑电图上没有相应的电描记图变化。随后，患儿的脑电图发生变化，呈现出高度失律的混乱模式，并伴有短暂的强直发作，高度失律模式减弱，符合婴儿痉挛症的特征。
由于患者数量较少，ISOD 相关癫痫发作的演变特征描述并不完善。我们报告了首例患有 ISOD 的儿童同时出现婴儿痉挛症和强肌张反射的病例。这扩展了与 ISOD 相关的表型，也应提醒临床医生不要假设所有异常运动都是癫痫发作。
