Duration and reliability of the silent period in individuals with spinal cord injury

Sfreddo, Hannah J; Wecht, Jaclyn R.; Alsalman, Ola; Wu, Yu‐Kuang; Harel, Noam Y.

doi:10.1038/s41393-021-00649-x

Cited by 6 publications

(6 citation statements)

References 29 publications

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“…Future studies are needed to strengthen the use of TMS for clinical assessments in individuals with SCI. There are discrepancies in the findings of TMS studies, for example, delayed ( 41 , 45 ) vs. non-delayed ( 42 , 47 ) MEP latencies, smaller ( 14 , 48 ) vs. larger ( 67 ) MEP amplitudes, absent ( 75 ) vs. similar ( 44 ) vs. prolonged ( 40 ) cSP, smaller ( 47 ) vs. large motor maps ( 81 ). The factors leading to these discrepancies need to be addressed.…”

Section: Discussionmentioning

confidence: 97%

“…Lower motor neuron lesions influence TMS measures and should be taken into consideration by use of F-waves ( 14 ), H-reflexes or lower motor neuron integrity tests ( 95 ). The psychometric properties of any technique are population specific, and currently only a few studies have investigated the psychometric properties of TMS-based measures in individuals with SCI ( 44 , 96 , 97 ). The smallest detectable change (SDC; the smallest change that is above the inherent measurement error and can be reliably detected) of TMS-based measures in proximal arm muscles is typically high for individuals with SCI ( 96 ).…”

Section: Discussionmentioning

confidence: 99%

“…The motor threshold, defined as TMS intensity (expressed as % maximum stimulator output; MSO) for eliciting consistent MEP, is typically higher in muscles impaired from SCI ( 40 , 44 – 48 ). In some cases, the thresholds can be too high to elicit MEP even with the maximum intensity (i.e., 100% MSO).…”

Section: Introductionmentioning

confidence: 99%

“…TMS can suppress ongoing muscle activities in the target muscles, causing electrical silence in the surface EMG ( Table 5 ). This brief interruption can be observed at subthreshold ( 45 , 46 ) and suprathreshold ( 40 , 44 , 69 ) intensities and is termed the contralateral silent period (cSP). The early part of cSP is thought to involve spinal inhibitory networks ( 70 ), whereas the later part involves intracortical circuits ( 71 ).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Utility of transcranial magnetic stimulation in the assessment of spinal cord injury: Current status and future directions

Arora

Desai

Kirshblum

et al. 2022

Front. Rehabilit. Sci.

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Comprehensive assessment following traumatic spinal cord injury (SCI) is needed to improve prognostication, advance the understanding of the neurophysiology and better targeting of clinical interventions. The International Standards for Neurological Classification of Spinal Cord Injury is the most common clinical examination recommended for use after a SCI. In addition, there are over 30 clinical assessment tools spanning across different domains of the International Classification of Functioning, Disability, and Health that have been validated and recommended for use in SCI. Most of these tools are subjective in nature, have limited value in predicting neurologic recovery, and do not provide insights into neurophysiological mechanisms. Transcranial magnetic stimulation (TMS) is a non-invasive neurophysiology technique that can supplement the clinical assessment in the domain of body structure and function during acute and chronic stages of SCI. TMS offers a better insight into neurophysiology and help in better detection of residual corticomotor connectivity following SCI compared to clinical assessment alone. TMS-based motor evoked potential and silent period duration allow study of excitatory and inhibitory mechanisms following SCI. Changes in muscle representations in form of displacement of TMS-based motor map center of gravity or changes in the map area can capture neuroplastic changes resulting from SCI or following rehabilitation. Paired-pulse TMS measures help understand the compensatory reorganization of the cortical circuits following SCI. In combination with peripheral stimulation, TMS can be used to study central motor conduction time and modulation of spinal reflexes, which can be used for advanced diagnostic and treatment purposes. To strengthen the utility of TMS in SCI assessment, future studies will need to standardize the assessment protocols, address population-specific concerns, and establish the psychometric properties of TMS-based measurements in the SCI population.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Utility of transcranial magnetic stimulation in the assessment of spinal cord injury: Current status and future directions

Arora

Desai

Kirshblum

et al. 2022

Front. Rehabilit. Sci.

View full text Add to dashboard Cite

show abstract

“…Another limitation is the low signal to noise ratio which was found to be at best similar to EEG and could be made worse due to SCI, which is thought to decrease the amplitude of spared descending signals [44]. However, previous work has demonstrated that transcranial magnetic stimulation in conjunction with voluntary effort can create motor evoked potentials that can be recorded on the surface of the skin over the spinal column above, at, and below the lesion in individuals who are motor and sensory complete (AIS A) [45].…”

Section: Discussionmentioning

confidence: 99%

Electrospinography for non-invasively recording spinal sensorimotor networks in humans

Steele,

Faraji,

Contreras-Vidal

2023

J. Neural Eng.

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Objective. Currently, few non-invasive measures exist for directly measuring spinal sensorimotor networks. Electrospinography (ESG) is one non-invasive method but is primarily used to measure evoked responses or for monitoring the spinal cord during surgery. Our objectives were to evaluate the feasibility of ESG to measure spinal sensorimotor networks by determining spatiotemporal and functional connectivity changes during single-joint movements at the spinal and cortical levels.Approach. We synchronously recorded electroencephalography (EEG), electromyography, and ESG in ten neurologically intact adults while performing one of three lower-limb tasks (no movement, plantar-flexion and knee flexion) in the prone position. A multi-pronged approach was applied for removing artifacts using H∞ filtering, artifact subspace reconstruction and independent component analysis. Next, data were segmented by task and independent components (ICs) of EEG were clustered across participants. Within-participant analysis of ICs and ESG data was conducted, and ESG was characterized in the time and frequency domains. Generalized Partial Directed Coherence (gPDC) analysis was performed within ICs and between ICs and ESG data by participant and task. Results. K-means clustering resulted in five clusters of ICs at Brodmann areas (BA) 9, BA 8, BA 39, BA 4, and BA 22. Areas associated with motor planning, working memory, visual processing, movement, and attention, respectively. Time-frequency analysis of ESG data found localized changes during movement execution when compared to no movement. Lastly, we found bi-directional changes in functional connectivity (p < 0.05, adjusted for multiple comparisons) within IC’s and between IC’s and ESG sensors during movement when compared to the no movement condition. Significance. To our knowledge this is the first report using high density ESG for characterizing lower limb movements. Our findings provide support that ESG contains information about efferent and afferent signaling in neurologically intact adults and suggests that we can utilize ESG to directly study the spinal cord.

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Clinical diagnostic utility of transcranial magnetic stimulation in neurological disorders. Updated report of an IFCN committee

Vucic¹,

Chen²,

Kiernan³

et al. 2023

Clinical Neurophysiology

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Duration and reliability of the silent period in individuals with spinal cord injury

Cited by 6 publications

References 29 publications

Utility of transcranial magnetic stimulation in the assessment of spinal cord injury: Current status and future directions

Utility of transcranial magnetic stimulation in the assessment of spinal cord injury: Current status and future directions

Electrospinography for non-invasively recording spinal sensorimotor networks in humans

Clinical diagnostic utility of transcranial magnetic stimulation in neurological disorders. Updated report of an IFCN committee

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