| ObjectiveTo investigate features of the magnetic resonance imaging in two pedigrees with hereditary spastic paraplegia type 4 and type 31, which were determined by genetic linkage analysis. To elaborate whether MRI may be regarded as one of assistant diagnostic indexes for HSP subtypes.Materials and MethodsIn this study, all two pedigrees were found in Linyi People's Hospital neurology clinic, consistent with the autosomal dominant mode of inheritance. All patients met diagnostic criteria for Harding. Severity of the disease was graded 1～5 according to previously published criteria. Two pedigrees were determined as SPG4 or SPG31 by genetic linkage analysis in previous work. MRI of brain and the whole spine were performed in these 8 patients and 16 age- and gender- matched control subjects utilizing a 1.5 T magnet. MR images were transferred to an imaging workstation for further analysis by two independent neuroraddiagnosis, blinded to clinical diagnosis. The area of the corpus callosum was measured from the midsagittal view, and the corpus callosum index was calculated as previously published. The cross-section areas of the spinal cord at levels of C2, C7, T4 and T9 were measured from T2-weighted axial images. Three measurements for each segment were obtained, and an average value was calculated. The data were treated with SPSS 13.0. p<0.05 is considered statistically significant.Results⑴All patients had grossly normal MRI of the brain with the exception of subjectⅢ10 of familyⅡ, who had mild brain atrophy. No atrophy of corpus callosum and abnormal T2 high signal intensity of white matter lesions were detected in MR images. The areaes of the corpus callosum, brain and corpus callosum index did not differ between affected patients and healthy age- and gender- matched controls.⑵MRI of the spinal cord revealed no signs of atrophy or abnormal cord signal in SPG4 subjects. Cervical and thoracic MRI of SPG31 subjects revealed atrophies of the spinal cord and enlarged subarachnoid cavity. There was symmetric patch or point flake high signal intensity in the gray matter on the axial image. There was a linear T2 hyperintense signal intensity in the grey matter and white matter of the spinal cord on the midsagittal image.⑶The cross-sectional areas of SPG4 subjects at the levels of C2, C7, T4 and T9 were (66.80±4.81) mm2, (51.53±3.30) mm2, (35.42±3.82) mm2 and (34.22±3.75) mm2, there was no significant abnormality between SPG4 subjects and controls. The cross-sectional areas of SPG31 subjects at the levels of C2, C7, T4 and T9 were (50.13±3.43) mm2, (40.45±2.00) mm2, (22.03±4.55) mm2 and (26.10±4.55) mm2. All of these values were less than those in the healthy control (t=6.331, 6.889, 4.647, 3.345, p<0.05).⑷An association between the spinal cord size and duration of the disease was analyzed using the Pearson correlation analysis. An association between the spinal cord size and severity of the disease was analyzed using Spearman rank correlation test. There was no association between the degree of spinal cord atrophy and severity and duration of the disease in these two genetic subtypes of HSP. ConclusionBrain MRI of SPG4 and SPG31 subjects revealed no atrophy of corpus callosum. Cervical and thoracic MRI of SPG31 subjects revealed atrophies of the spinal cord and enlarged subarachnoid cavity. There was a abnormal linear T2 hyperintense signal intensity of the spinal cord. While no atrophies of the spinal cord were detected in SPG4 subjects. There was no association between the cross-sectional areas at the levels of C2, C7, T4, T9 and severity and duration of the disease in these two genetic subtypes of HSP. These observations indicate that the degree of spinal cord atrophy varies among different genetic types of HSP. MRI may be to some extent regarded as a assistant diagnostic index for HSP subtypes. |
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