Identifying the injury in demyelinating cervical spinal cord disease: A diffusion tensor imaging and tractography study

Background & Objectives: Multiple sclerosis (MS), neuromyelitis optica (NMO) and acute transverse myelitis (ATM) are common diseases in neurology; however their corresponding cervical spinal cord involvements are still ambiguous. The purpose of this study was to demonstrate the utility of diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) in identifying the injury in cervical spinal cord. Methods: Nine patients and nine healthy volunteers were enrolled in this study. Conventional sequences and DTI scan were performed on each participant. Results: The average fractional anisotrophy (FA) values of the cervical cord in patients with acute cerebral type MS, acute or stationary cerebrospinal type MS, acute NMO, or acute ATM were all significantly decreased relative to the control group (p <0.05). As to the cerebrospinal type MS, the changes in acute-stage patients were more apparent (p <0.05). The average FA value of the cervical cord in acute NMO was decreased more extensively, involving the normal-appearing spinal cord (p <0.05). In patients with MS or NMO, The lesions showed significantly hypointense on FA images and directionally encoded color (DEC) images, nevertheless the pathological areas on DTI images were no significantly different from those on routine sequences. On DTT, the fiber tracts in the lesion-involved regions were all sparser than that in control regions, nevertheless interruption or impairment of fiber tracts could only be noted in NMO patients. Bilateral differences of average FA values in the cervical cord was noted in one case with ATM and another case with MS (p <0.05), and the decrease of FA values was significant in the main side of clinical presentations. Conclusion: DTI and DTT may be a sensitive measure for early cervical injury in MS, NMO and ATM. Neurology Asia 2016; 21(1) : 73 – 80 Address correspondence to: Shaokuan Fang MD PhD, Department of Neurology, The First Teaching Hospital of the Jilin University, Changchun, China. Tel: (86) 431-88782396; e-mail: [email protected] INTRODUCTION Myelopathy is frequent in demyelinating diseases of central nervous system where acute inflammatory response and cervical spinal involvement is common. In the spectrums of demyelinating diseases, multiple sclerosis (MS), neuromyelitis optica (NMO) and acute transverse myelitis (ATM) are common particularly among Asians, often resulting in significant disability. The commonly occurring lesions in cervical spinal cord can be detected with conventional sequences of MRI in acute-onset patients. However, differential diagnosis often depends upon laboratory tests to demonstrate the absence of associated systemic diseases. Besides differential diagnosis, quantitative analysis of the disease severity as well as the prognostic evaluation based on the current radiological examinations is still unavailable. Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) are advanced MRI techniques that enables the measurement of the anisotropic restricted diffusion of water in tissue in order to produce neural tract images. It enables the quantification of diffusion anisotropy, and detection of subtle changes in the white matter which is normally not observed on conventional MRI images. Recently, the application of DTI in cerebral diseases, especially MS, have been reported. However, evidence on the clinical value of DTI in spinal cord diseases, especially in patients with NMO or ATM is lacking. In the present study, we used DTI and clinical functional assessment systems to quantitatively evaluate the severity of disease in patients with MS, NMO and ATM. Neurology Asia March 2016