A Study on Trans-Neuronal Striato-Nigral Degeneration-Induced Movement Disorders after Stroke: Evaluation with Grey Matter Suppression Ir and Diffusion Tensor Imaging( I )

Background Stroke is the third most common cause of death and a primary source of disability among the elderly in Taiwan. Ischemic stroke accounts for 80 to 85 percent of all strokes and occurs most frequently in the middle cerebral artery (MCA) territory. Previous studies have shown a subgroup of MCA infarct patients who developed movement disorders in the subacute period of stroke, had delayed recovery. The postinfarct movement disorders include chorea, dystonia, tremors and parkinsonism which appear to be caused by secondary trans-neuronal degeneration of the substantial nigra (SN) along with Wallerian degeneration of the corticospinal tracts. Because the occurrence of trans-synaptic neuronal degeneration is difficult to quantify, we aim to investigate quantitatively the delayed neuronal changes in SN and motor-related structures using MR inversion recovery grey matter-suppressed (GMS) technique, diffusion tensor imaging (DTI) and proton MR spectroscopy in these groups of patients in an attempt to find out the causal relationship between the imaging findings and specific movement disorders. Our study results may shed light on new therapeutic targets for post-infarct movement disorders and discover prognosticating biomarkers for the levels of recovery of motor function that further help to innovate an adapted rehabilitation programs for stroke patients. Materials and Methods In this 3-year project, we plan to enroll 30 patients who sustain unilateral or bilateral MCA infarct and develop movement disorders later on after ictus. Another 60 MCA infarct patients without movement disorders and 30 age- and gender-matched normal elderly subjects will also be included for control. Various functional scales for specific movement disorders will be implemented. First year We aim to optimize the scanning parameters for different MR sequences and design the post-processing methods including quantitative analysis of GMS, DTI images and proton MR spectroscopy. Second year and Third year-statistic analysis We will begin to enroll 90 patients and 30 normal controls in the second and third years. MRI examinations are arranged seven days and one month, respectively, after infarct. A comparison of derived functional and clinical parameters between stroke patients and control groups will be explored using statistical analysis in the third year. Project Aims (1) To evaluate quantitatively the trans-neuronal degeneration in substantia nigra using grey matter-suppressed inversion recovery sequence; (2) To study the impaired microstructural integrity of motor-related structures associated with Wallerian degeneration using DTI; (3) To measure metabolic changes of the extrapyramidal system (striatum) by MR spectroscopy; (4) To correlate quantitative imaging results with the clinical assessment and functional recovery scales at subacute or chronic stages of stroke patients and to compare with the normal control group.