Diffusion Tensor Imaging Evaluation of Neural Network Development in Patients Undergoing Therapeutic Repetitive Transcranial Magnetic Stimulation following Stroke

Abstract

We aimed to investigate plastic changes in cerebral white matter structures using diffusion tensor imaging following a 15-day stroke rehabilitation program. We compared the detection of cerebral plasticity between generalized fractional anisotropy (GFA), a novel tool for investigating white matter structures, and fractional anisotropy (FA). Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) of 2400 pulses applied to the nonlesional hemisphere and 240 min intensive occupation therapy (OT) daily over 15 days. Motor function was evaluated using the Fugl-Meyer assessment (FMA) and Wolf Motor Function Test (WMFT). Patients underwent diffusion tensor magnetic resonance imaging (MRI) on admission and discharge, from which bilateral FA and GFA values in Brodmann area (BA) 4 and BA6 were calculated. Motor function improved following treatment (p < 0.001). Treatment increased GFA values for both the lesioned and nonlesioned BA4 (p < 0.05, p < 0.001, resp.). Changes in GFA value for BA4 of the lesioned hemisphere were significantly inversely correlated with changes in WMFT scores (R2 = 0.363, p < 0.05). Our findings indicate that the GFA may have a potentially more useful ability than FA to detect changes in white matter structures in areas of fiber intersection for any such future investigations.

Predicting Recovery of Upper Extremity Motor Function After Stroke According to the NovEl Intervention Using Repetitive Transcranial Magnetic Stimulation and Occupational Therapy: NEURO

“…14 Since there were no data on the time of onset of stroke in patients, it was difficult to estimate and compare the predicted scores of the spontaneous biological recovery using the PRR formula. 13, 14 However, these results are consistent with those of previous reports, 7, 18 and more than half of patients with NEURO who had a longer time since the onset of stroke recovered more. How NEURO alters the spontaneous recovery estimated in chronic stroke patients needs to be tested using acute phase data.…”

“…[15][16][17] Although the PRR and the PREP algorithms can be used within days of stroke patients to provide accurate predictions of the upper extremity functional outcomes at 3 to 6 months after stroke. 14,17 Patients who were treated with NEURO were those who had stroke for longer than 6 months; 7,18 therefore, it was difficult to predict the recovery from hemiparesis without the initial acute values, such as in those who received NEURO. On the other hand, the long-term recovery prediction models, as time series functional changes, were substituted into a logarithmic model for analysis.…”

“…Studies have verified upper extremity motor recovery in hemiplegic stroke patients by comparing function pre-and posttreatment. [22][23][24] The effects of NEURO have been demonstrated at the population level, 8,18 but no known studies have evaluated the effects of NEURO at the individual level. Moreover, it is unclear whether recovery from paralysis is maintained after treatment; there is thus a need to verify whether the recovered function is maintained after it plateaus even with continued treatment when recovered by further treatment.…”

Aberrant Maturation of the Uncinate Fasciculus Follows Exposure to Unpredictable Patterns of Maternal Signals

“…These measures rely on the tensor model, which assumes a single fiber orientation per voxel and does not properly account for fiber crossing, bending, or twisting (Alexander et al, 2001). A strength of our approach of modeling multiple fiber orientations using orientation distribution functions is possibly more likely to approximate microstructural properties of complex neural tissue than the tensor model (Gorczewski et al, 2009;Fritzsche et al, 2010;Yamada et al, 2018).…”

“…GFA is one of several model-free diffusion measures and is known to correlate with fractional anisotropy of the tensor model. GFA was used to assess the structural integrity of complex tissues in a clinical setting, particularly when there are heterogeneous fiber tissues (Koh et al, 2018;Yamada et al, 2018), and has been used in studies of affective disorders (Chiang et al, 2016;Lo et al, 2017). However, it should be noted that the accuracy of GFA depends on the type of tissue being evaluated as well as the b value at which the raw data are collected (Tuch et al, 2002;Tuch, 2004;Gorczewski et al, 2009;Fritzsche et al, 2010).…”