From Silence to Awakening: The Role of Amplitude of Low-Frequency Fluctuations in Predicting Recovery After Spinal Cord Stimulation.

BACKGROUND

Disorders of consciousness (DoCs) following traumatic brain injury (TBI), or cerebrovascular disease (CVD) are difficult to prognose, as reliable biomarkers are lacking. Resting-state functional magnetic resonance imaging (fMRI) amplitude of low-frequency amplitude (ALFF) may capture etiology-specific neural activity, but its prognostic value for spinal cord stimulation (SCS) outcomes remains unknown. In this study we therefore investigated etiology-specific ALFF patterns in TBI- and CVD-induced DoCs and evaluated their prognostic value for recovery after SCS.

METHODS

Resting-state fMRI data from patients with TBI (n = 16) and CVD (n = 15), and healthy controls (n = 12), were analyzed. Whole-brain ALFF differences were also compared between the groups. Correlations between ALFF and 6-month post-SCS Coma Recovery Scale-Revised (CRS-R) score improvements were assessed. Logistic regression was used to identify consciousness recovery markers.

RESULTS

Compared with healthy controls, patients with TBI demonstrated a significant increase in ALFF within the bilateral insula, thalamus, and brainstem (p < 0.05), suggesting compensatory neural hyperactivity potentially involving glutamatergic pathways. Patients with CVD exhibited elevated ALFF in the contralateral sensorimotor cortex (p < 0.05), indicating ipsilateral neural reorganization. Notably, the thalamic ALFF were strongly correlated with consciousness recovery, as measured by improvements in CRS-R score at 6 months in both the TBI (r= 0.64, p = 0.0071) and CVD (r = 0.59, p = 0.02) groups. Furthermore, logistic regression analysis identified increased ALFF in the anterior cingulate cortex-thalamic loop (odds ratio [OR] = 3.21, p < 0.05) as a potential cross-etiology biomarker for recovery following SCS.

CONCLUSIONS

ALFF reveal distinct neuroplasticity mechanisms, including compensatory activation in TBI and ipsilateral reorganization in CVD. Elevated anterior cingulate cortex (ACC)-thalamic ALFF are a key cross-etiology biomarker for consciousness recovery to guide SCS target selection.