Rakowicz Maria, Zdzienicka Elzbieta, Poniatowska Renata, Waliniowska Elzbieta, Sułek Anna, Jakubowska Teresa, Niedzielska Krystyna, Rola Rafał, Wierzbicka Aleksandra, Hoffman-Zacharska Dorota, Głazowski Czesław, Jakubczyk Tomasz, Niewiadomska Maria, Zaremba Jacek
Zakład Neurofizjologii Klinicznej, Instytut Psychiatrii i Neurologii, ul. Sobieskiego 9, 02-957 Warszawa.
Neurol Neurochir Pol. 2005 Jul-Aug;39(4):263-275.
Spinocerebellar ataxias type 1 (SCA1) and type 2 (SCA2) belong to neurodegenerative disorders of autosomal dominant inheritance, genetically and clinically heterogeneous, caused by the expansion of CAG trinucleotides. Trunk and limb ataxia, dysarthria, dysphagia, gaze palsy, sensory and motor axonal neuropathy are the dominant features in both entities. The aim of the study was to evaluate the differences between genotype and phenotype based on clinical and electrophysiological assessment of the visual, auditory pathways, and EEG alterations in comparison with the cerebellar and brain atrophy in MRI.
44 patients with SCA1 and 24 cases with SCA2 confirmed molecularly were examined neurologically and using the International Cooperative Ataxia Rating Scale (ICARS). A correlation of clinical symptoms and signs, and CAG repeat numbers with EEG, visual (VEP) and brainstem auditory (BAEP) evoked potentials, and MRI alterations were evaluated.
A statistically significant negative correlation between the age of disease onset and number of CAG repeats in both types of SCA was found. Examined patients with SCA2 were younger, with longer disease duration and more pronounced cerebellar and brain atrophy in MRI. We found a significant correlation between ICARS and CAG repeats in this group. The dysphagia, pyramidal tract involvement and depressive reaction were significantly frequent in SCA1 patients. However in SCA2 patients, the peripheral nerve damage and extrapyramidal signs were more prominent. The amplitude of P100 visual evoked potentials was significantly lower in SCA1 patients and negatively correlated with CAG repeats.
These results provide further evidence for the phenotypic differences of genetically defined SCA1 and SCA2 patients, expressed by more frequent involvement of the pyramidal tract and depression reaction in SCA1, in contrast to peripheral nerve involvement and extrapyramidal signs in the clinical feature of SCA2 phenotype. Furthermore, atrophy of the brain and cerebellum revealed in MRI was more pronounced than electrophysiological functional alterations, especially in SCA2. The decreased amplitude of P100 VEP in SCA1 patients was the only electrophysiological parameter differentiating between both groups of patients.
1型脊髓小脑共济失调（SCA1）和2型脊髓小脑共济失调（SCA2）属于常染色体显性遗传的神经退行性疾病，在遗传和临床方面具有异质性，由CAG三核苷酸扩增引起。躯干和肢体共济失调、构音障碍、吞咽困难、凝视麻痹、感觉和运动轴索性神经病是这两种疾病的主要特征。本研究的目的是通过对视觉、听觉通路的临床和电生理评估以及脑电图改变，并与MRI中的小脑和脑萎缩情况进行比较，来评估基因型和表型之间的差异。
对44例经分子确诊的SCA1患者和24例SCA2患者进行了神经学检查，并使用国际合作共济失调评定量表（ICARS）。评估了临床症状和体征、CAG重复次数与脑电图、视觉诱发电位（VEP）、脑干听觉诱发电位（BAEP）以及MRI改变之间的相关性。
在两种类型的SCA中均发现疾病发病年龄与CAG重复次数之间存在统计学上显著的负相关。接受检查的SCA2患者较年轻，病程较长，MRI显示小脑和脑萎缩更明显。我们发现该组中ICARS与CAG重复次数之间存在显著相关性。SCA1患者吞咽困难、锥体束受累和抑郁反应更为常见。然而，在SCA2患者中，周围神经损伤和锥体外系体征更为突出。SCA1患者的P100视觉诱发电位振幅显著降低，且与CAG重复次数呈负相关。
这些结果为基因定义的SCA1和SCA2患者的表型差异提供了进一步证据，表现为SCA1中锥体束受累和抑郁反应更常见，而SCA2表型的临床特征为周围神经受累和锥体外系体征。此外，MRI显示的脑和小脑萎缩比电生理功能改变更明显，尤其是在SCA2中。SCA1患者P100 VEP振幅降低是区分两组患者的唯一电生理参数。
