A Comparison Analysis Of Magnetic Resonance Imaging Features Of Optic Nerve And Spinal Cord Of In The Patients With Neuromyelitis Optica And Multiple Sclerosis

Objective: To investigate the differences of magnetic resonance imaging (MRI) fingdings in the optic nerve and the spinal cord between the patients with neuromyelitis optica (NMO) and multiple sclerosis (MS).Methods: Subjects who were diagnosed or suspected as NMO or MS in the hospital from December 2005 to June 2008 underwent the brain, optic and spinal cord MRI scanning and imaging analysis. In reference to MRI records, the results of cerebrospinal fluid (CSF) and visual evoked potential (VEP), patients who fulfilled the latest diagnostic criteria for NMO or McDonald diagnostic criteria for MS were enrolled and the follow-up study was carried out. Thirty-two healthy volunteers were enrolled as control subjects.Results: Forty-one patients with NMO and 121 patients with MS were included into this study. (1) Optic nerves imaging analysis: The shapes of bilateral optic nerves were straight in healthy volunteers. The coronal T₂WI with fat suppression images showed just a moiety of the optic nerve sheath demonstrated lightly higher signal, and the"double track-like"sign on the axial T₂WI with fat suppression images was not obvious. All of NMO patients, the signal of the optic nerve sheath at unilateral or bilateral sides increased obviously and appeared the"double track-like"sign on the axial T₂WI with fat suppression images and showed ringlike sign on the coronal T₂WI with fat suppression images. Twenty-two patients (53.7%) had optic swelling accompanied by distortion in the acute stage, and 17 cases (41.5%) had high signal spots in optic nerve on the coronal T₂WI with fat suppression images. In the remission stage, the MRI of 15 patients (36.6%) showed that the optic nerves at unilateral or bilateral sides were atrophied or thinned. At the end of the study, the coronal T₂WI with fat suppression images showed 35 cases (80.5%) had high signal spots in the optic nerves. Among 121 patients with MS, there were 81 cases (66.9%) whose optic nerves were abnormal on MRI,whicun showed the signal of the optic nerve sheath at unilateral (32 cases, 26.4%) or bilateral (49 cases, 40.5%) sides discontinuous or whole course intensified obviously in the axial T₂WI with fat suppression images ,and the signal of retrobulbar optic nerve sheath in 23 patients (28.4%) strengthened topically. Twenty-five patients (20.7%) had optic swelling accompanied by distortion in acute stage. Fifteen cases (12.4%) had optic distortion accompanied by atrophy in the remission stage. At the end of the study, there were 12 cases (9.9%) in whom the coronal T₂WI with fat suppression images showed high signal spots in the optic nerve. (2) Spinal cord imaging analysis: In all of NMO patients, MRI showed the damaged segments of spinal cord were more than 3.And the number of damaged segments were more than 5 (32 cases, 78.1%), the average damaged segments were 7.59±4.32, and most of them (33 cases, 80.5%) suffered either cervical spinal cord damage or cervical - thoracic spinal cord damage. The lesions changed continually. The axial T₂WI images showed the signal of the peripheral and central regions in the spinal cord increased or demonstated nodular high signal, and the increased signal was obvious especially in the central region. MRI showed the spinal cord swelled obviously in acute stage. There were 69 patients showed spinal cord damage in MS group. There were 41 patients (59.4%) in whom the damaged segments were more than 3, the average damage segments were3.57±2.68, and they appeared which were discontinuously. The axial T₂WI images showed most of the lesions were in the peripheral regions of spinal. The spinal cord swelling was unobvious in acute stage. There was significant difference between the results of MRI about damaged segments in two groups (p<0.01). (3) Used the coronal T₂WI with fat suppression images which showed high signal spots in the optic nerve as the standard of abnormity. The results of MRI had significant difference in two groups (p <0.01).Compared with the result of VEP in NMO group, the overall sensitivity of MRI showed optic nerve demyelination was 94.6%, but the sensitivity in acute stage was only 43.6%.Conclusion: (1) There is a certain difference in the MRI findings of the optic nerve between NMO and MS groups. The signal increasing of the optic nerve sheath (the"double track-like"sign), the optic nerve swelling, thinning and distortion, and the high signal spot in the optic nerve showed by MRI in NMO group are more common and more severe than MS. (2) There are different characteristics in the changes of spinal cord damages in patients with NMO and MS. All of the NMO patients had spinal cord damages, which were continuous and have a wide range of signal abnormalities, and the dmaged spinal cord segments are often≥5 segments. Only some of MS patients show spinal cord damages and the abnormal signal ranges are limited, and discontinuous. (3) The changes of the optic nerves and spinal cord can be showed clearly by MRI, so MRI should be the preferred method of imaging examnation. MRI examination has important clinical value in diagnosis and differential diagnosis between NMO and MS.