Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a form of cerebellar ataxia related to mutations in the SACS gene on chromosome 13q12.12 encoding sacsin protein. Characteristic clinical features are ataxia, spasticity, distal muscle wasting, neuropathy, dysarthria, nystagmus, and finger or feet deformities.

The presented case concerns a 32-year-old man with clinical diagnosis of ARSACS. Magnetic resonance imaging (MRI) scans of the brain revealed cerebellar atrophy typical of the disease while neuroimaging of the C1-C3 and C6-Th12 segments showed only the thin thoracic spinal cord. The patient died suddenly and a gross examination of the spinal cord revealed extraspinal tumour at the C4-C5 levels, which turned out to be an additional spinal cord. Microscopic examination showed an extensive ischemic necrosis involving C6-Th5 segments of the proper spinal cord, and disturbed intrinsic structure containing many pathological vessels of the extra spinal cord.

Lack of visualization of C4-C5 spinal cord segments on MRI scans made diagnosis of diplomyelia in vivo impossible. However, diplomyelia does not exclude coexistence of ARSACS because of the occurrence of such clinical symptoms as dysarthria or nystagmus which cannot be explained by the presence of the spinal cord defect. The possibility of congenital malformations of the spinal cord in adults should be remembered as their early identification and surgical correction can improve neurological symptoms.

中文翻译：

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临床怀疑Charlevoix-Saguenay型常染色体隐性痉挛性共济失调（ARSACS）的患者中的双文凭。

Charlevoix-Saguenay（ARSACS）的常染色体隐性痉挛性共济失调是小脑共济失调的一种形式，与编码囊囊蛋白的13q12.12染色体上的SACS基因突变有关。典型的临床特征是共济失调，痉挛，远端肌肉消瘦，神经病变，构音障碍，眼球震颤和手指或足部畸形。

本病例涉及具有ARSACS临床诊断的32岁男子。大脑的磁共振成像（MRI）扫描显示出该病典型的小脑萎缩，而C1-C3和C6-Th12节段的神经成像仅显示胸椎脊髓细小。该患者突然死亡，对脊髓的全面检查显示，脊柱外肿瘤处于C4-C5水平，原来是另外一根脊髓。显微镜检查显示广泛的缺血性坏死，累及适当脊髓的C6-Th5节段，并扰乱了固有结构，其中包含许多额外脊髓的病理血管。

MRI扫描中缺乏C4-C5脊髓节段的可视化，因此不可能在体内诊断双核细胞增多症。然而，由于存在诸如构音障碍或眼球震颤等临床症状的发生，因此不能通过存在脊髓缺损来解释双核细胞增多症并存。应该记住成人脊髓先天性畸形的可能性，因为他们的早期识别和手术矫正可以改善神经系统症状。