Kalita Jayantee, Soni Neetu, Dubey Deepanshu, Kumar Sunil, Misra Usha Kant
1 Department of Neurology, Sanjay Gandhi Post Graduate medical Sciences , Lucknow , India.
2 Department of Radiodiagnosis, Sanjay Gandhi Post Graduate medical Sciences , Lucknow , India.
Br J Radiol. 2018 Nov;91(1091):20180086. doi: 10.1259/bjr.20180086. Epub 2018 Jul 20.
: To evaluate optic nerve involvement in subacute combined degeneration (SACD) using diffusion tensor imaging (DTI) and visual evoked potential (VEP) studies, and their changes following cobalamine treatment.
: Six patients with SACD and six healthy matched controls were included. Visual acuity, field of vision, and color vision were tested. Pattern shift VEP was done, and P100 latency and amplitude were measured. Optic nerve MRI, and DTI of optic nerve to muscle ratio were measured, and fractional anisotropy ratio (FAR), axial diffusivity ratio (ADR), radial diffusivity ratio (RDR), and mean diffusivity ratio (MDR) were calculated. The patients received hydroxyl cobalamine 1000 µg intramuscularly and their clinical examination, VEP and DTI studies were repeated at 3 months.
: The age of the patients ranged between 16 and 60 years and two were females. Their visual acuity, field of vision, and color vision were normal. P100 latency was prolonged in five patients (10 eyes) and amplitude was reduced in one (1 eye). The SACD patients had reduced FAR (1.94 ± 0.55 vs 2.81 ± 0.42; p = 0.01) and increased MDR (1.00 ± 0.04 vs 0.95 ± 0.01; p = 0.01) and RDR (0.96 ± 0.03 vs 0.89 ± 0.01; p = 0.002) compared to the controls. The FAR value correlated with P100 latency (r = -0.88). At 3 months, FAR value increased which was associated with improvement in P100 latency.
: In SACD patients, optic nerve FAR is reduced and correlates with P100 latency. Both these parameters improve on cobalamine treatment.
: Subclinical VEP abnormalities are common in SACD but conventional MRI sequence of optic nerve is normal. DTI of optic nerve reveals reduced fractional anisotropy (FA) values which improve after cobalamine treatment. FA values correlate with prolongation of P100 latency. DTI and VEP abnormalities suggest subclinical optic nerve myelin dysfunction.
使用弥散张量成像（DTI）和视觉诱发电位（VEP）研究评估亚急性联合变性（SACD）患者的视神经受累情况，以及钴胺素治疗后的变化。
纳入6例SACD患者和6例健康对照者。检测视力、视野和色觉。进行图形翻转VEP检查，测量P100潜伏期和波幅。进行视神经MRI检查，并测量视神经与肌肉的DTI，计算各向异性分数比（FAR）、轴向扩散率比（ADR）、径向扩散率比（RDR）和平均扩散率比（MDR）。患者接受1000μg羟钴胺素肌肉注射，3个月后重复进行临床检查、VEP和DTI研究。
患者年龄在16至60岁之间，2例为女性。他们的视力、视野和色觉均正常。5例患者（10只眼）的P100潜伏期延长，1例患者（1只眼）的波幅降低。与对照组相比，SACD患者的FAR降低（1.94±0.55对2.81±0.42；p=0.01），MDR升高（1.00±0.04对0.95±0.01；p=0.01），RDR升高（0.96±0.03对0.89±0.01；p=0.002）。FAR值与P100潜伏期相关（r=-0.88）。3个月时，FAR值升高，这与P100潜伏期的改善相关。
在SACD患者中，视神经FAR降低且与P100潜伏期相关。这两个参数在钴胺素治疗后均有改善。
亚临床VEP异常在SACD中常见，但视神经的传统MRI序列正常。视神经DTI显示各向异性分数（FA）值降低，在钴胺素治疗后改善。FA值与P100潜伏期延长相关。DTI和VEP异常提示亚临床视神经髓鞘功能障碍。
