中枢神经系统表面铁沉积症(superficial siderosis of the central nervous system, SSCNS)是由于慢性反复性出血进入脑脊液而导致过多的铁沉积在脑干、小脑、脊髓乃至部分脑神经表面所致的神经系统损害,较为罕见,肿瘤是出血源之一。目前国内在其诊治方面存在以下不足:认识较晚,诊断病例较少,长期随访资料匮乏,病因诊断不够重视,漏诊率较高,治疗水平较国外存在较大差距。SSCNS典型临床表现为:双侧进行性神经性耳聋、小脑共济失调和锥体束征阳性,称为SSCNS三联征,但同时具备三联征的患者较少,给及时诊断带来一定困难。MRI对确诊该病有重要意义,铁沉积在小脑、脑干、脊髓等表面呈特征性线状低信号,SE-T₂WI呈细线条,GE-T₂WI及磁敏感加权成像序列(susceptibility weighted imaging,SWI)呈显著粗线条。唯一有效的治疗方法是确定出血源并清除,MRI检查同样有助于寻找出血源,因此,如果考虑SSCNS,必须进行脑、脊柱MRI检查以寻找病因。本文报道1例37岁男性SSCNS患者,临床主要表现为共济失调、神经性耳聋和嗅觉减退,MRI表现有典型的中枢神经系统表面T2加权低信号,病因追查发现脊髓下端及马尾、终丝部巨大占位病变,经手术切除并组织病理学检查提示黏液乳头型室管膜瘤(myxopapillary ependymoma,MPE)。结合文献复习探讨了MPE继发SSCNS的机制,并对SSCNS的病因、临床表现、诊断以及治疗进行综述,以提高临床医师对该病的认识及诊断水平,尤其强调对该病病因的查找有利于治疗方案的准确制定。

Superficial siderosis of the central nervous system (SSCNS) is a rare disorder caused by hemosiderin deposits in the subpial layers of the brain and spinal cord due to prolonged or recurrent low-grade bleeding into the cerebrospinal fluid (CSF). Central nervous system tumor could be one of the sources of bleeding. Some problems exist at present regarding the diagnosis and treatment of SSCNS in China. On account of fewer cases, the insufficient awareness of the condition, and the lack of long-term follow-up data, enough attention has not been paid to etiological diagnosis. The speculative high rate of missed diagnoses of SSCNS indicates a great disparity in the treatment from the world’s advanced level. Related data of clinical and basic research need to accumulate as soon as possible to promote the clinical diagnosis and treatment of the disease. The progressive neurological deficits are involved in the typical clinical manifestations of SSCNS with a triad of bilateral symmetrical sensorineural hearing loss, cerebellar ataxia and signs of corticospinal tract dysfunction. Nevertheless, there are few patients with the triad signs at the same time, which lead to a delayed diagnosis or misdiagnosis. Detection of this disease was commonly post-mortem until the advent of MRI with signal and location characteristics, which made diagnosis easier. Siderosis appears as a hypointense rim covering the surface of the cerebellum, the brain stem, the spinal cord, similar to a black pencil line, thin on SE-T2-weighted images, thick and cons-picuous on GE-T2-weighted images or on susceptibility-weighted imaging (SWI). The only effective way of treating the disorder is to identify the source of bleeding and remove it. MR examination is useful for seeking a source of bleeding too. Therefore, once superficial siderosis is considered, lesions of the central nervous system must be searched using MRI of the brain and spine. We report here a 37-year-old male diagnosed of SSCNS with the classical clinical symptoms of cerebellar ataxia, sensorineural hearing loss and myelopathy. T2-weighed MRI showed characteristic marginal hypo-intensity around the central nervous system. Etiological explorations revealed a large conus medullaris / cauda equina ependymoma filling the lumbosacral spinal canal, a myxopapillary ependymoma (MPE) confirmed by surgical resection and histopathological examination. The related literature was reviewed to ascertain the mechanism of SSCNS secondary to MPE, and to discuss the pathogenesis, clinical features, diagnosis and treatment of SSCNS. This paper aims to improve the awareness of SSCNS and diagnostic level, and to lay stress on the etiological explorations that is beneficial to the development of exact treatment plan.