Diffusion Tensor Imaging and Motor-Evoked Potential Changes in 2 Patients with Locked-In Syndrome Due To Brainstem Stroke

Objective: Locked-in syndrome is a devastating state that occurs after brainstem stroke. The combined use of Diffusion Tensor Imaging (DTI) and Motor-Evoked Potential (MEP) monitoring has the potential to confirm and evaluate concisely the damage to the pyramidal pathway in the brainstem, and it is possible that DTI and MEP changes during the clinical course could reflect the clinical outcome. Clinical Presentation: Two patients were admitted to the hospital because of sudden weakness affecting the four extremities and an inability to talk. The patients presented with quadriplegia, anarthria, and preserved consciousness and intellectual functioning, but they could not speak and could only communicate with the medical staff by blinking their eyes. Brain CTs showed hypo density in the ventral part of the upper brainstem in one case and hyper density in the same area in the other. Intervention: Positive-pressure ventilation assistance was performed after admission to the hospital, and other treatments were also administered, including antiplatelet aggregation in response to brainstem infarction and hemostasis in response to brainstem hemorrhage. DTI and MEP monitoring were conducted during their hospital stays. Conclusion: DTI demonstrated that FA values were decreased and that the white matter fibers descending through the brainstem were significantly reduced in number on admission. Both FA values and the number of the white matter fibers were increased two weeks after admission. Cortical MEPs were absent on admission but were observed two weeks later as FA values increased. The changes observed by DTI were associated with appearance of the MEPs, and both were positively correlated with motor function.