Influence of inter-stimulus interval of spinal cord stimulation in patients with disorders of consciousness: A preliminary functional near-infrared spectroscopy study

• Published in: NeuroImage clinical Vol. 17; pp. 1 - 9
• Main Authors: Zhang, Yujin, Yang, Yi, Si, Juanning, Xia, Xiaoyu, He, Jianghong, Jiang, Tianzi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.01.2018; Elsevier
• Subjects: Adolescent; Adult; Brain - metabolism; Brain - physiopathology; Child; Consciousness Disorders - diagnostic imaging; Consciousness Disorders - metabolism; Consciousness Disorders - therapy; Disorders of consciousness; Female; Functional near-infrared spectroscopy; Glasgow Outcome Scale; Hemodynamics - physiology; Humans; Inter-stimulus interval; Male; Middle Aged; Prefrontal cortex; Regular; Spectroscopy, Near-Infrared; Spinal cord stimulation; Spinal Cord Stimulation - methods; Time Factors; Young Adult; SCS; CBF; JFKCRS-R; LTP; rCBV; DBS; DOC; Inter-stimulus interval; ISI; fNIRS; EEG; Disorders of consciousness; Spinal cord stimulation; MSN; GOS; Prefrontal cortex; Functional near-infrared spectroscopy; fMRI; MBLL; HbO; FWHM; HbR; HbT; TMS; MCS; ARAS; VS; SCS, spinal cord stimulation; DBS, deep brain stimulation; DOC, disorders of consciousness; FWHM, full-width-at-half-maximum; TMS, transcranial magnetic stimulation; HbT, total hemoglobin; fNIRS, functional near-infrared spectroscopy; MBLL, modified Beer-Lambert law; HbO, oxygenated hemoglobin; MCS, minimally conscious state; ISI, inter-stimulus interval; ARAS, ascending reticular activating system; fMRI, functional magnetic resonance imaging; MSN, medium spiny neuron; VS, vegetative state; LTP, long-term potentiation; CBF, cerebral blood flow; EEG, electroencephalography; HbR, deoxygenated hemoglobin; rCBV, regional cerebral blood volume; GOS, Glasgow Outcome Scale; JFKCRS-R, JFK Coma Recovery Scale
• ISSN: 2213-1582; 2213-1582
• DOI: 10.1016/j.nicl.2017.09.017

Spinal cord stimulation (SCS) is a promising treatment for disorders of consciousness (DOC), but the underlying mechanism and most effective procedures remain uncertain. To optimize the protocol, previous studies evaluated the frequency-specific effects of SCS on neurophysiological activities. However, whether and how the inter-stimulus interval (ISI) parameter affects the SCS neuromodulation in DOC remains unknown. We enrolled nine DOC patients who had implanted SCS devices and conducted three different durations of ISIs. Using functional near-infrared spectroscopy (fNIRS), we monitored the blood volume fluctuations in the prefrontal and occipital cortices during the SCS. The results showed that short stimuli (30s) induced significant cerebral blood volume changes, especially in the prefrontal cortex, an important area in the consciousness system. By comparing the mean value of the responses from the first and the last block in each session, a shorter ISI was found to improve the blood volume in the prefrontal cortex. This phenomenon was more significant for the subgroup of patients with a favorable prognosis. These preliminary results imply that the ISI may be an important factor for SCS. The research paradigm proposed here also provides insights for further quantitative evaluations of the therapeutic effects of neuromodulation. •Spinal cord stimulation rapidly evokes activity in consciousness-related brain areas.•Inter-stimulus interval of neuromodulation is important for treating disorders of consciousness.•Shorter inter-stimulus interval can better improve the blood volume in frontal area.•Near-infrared spectroscopy is feasible for evaluating neuromodulation effects.