Poster No:
2056
Submission Type:
Abstract Submission
Authors:
Na Jin Seo1, Christian Schranz1, Adam Baker1
Institutions:
1Medical University of South Carolina, Charleston, SC
First Author:
Na Jin Seo
Medical University of South Carolina
Charleston, SC
Co-Author(s):
Introduction:
Many stroke survivors suffer from persistent impairment in hand function, even after completing a full course of rehabilitation services (Lawrence et al. 2001). Hand impairment diminishes stroke survivors' abilities to perform activities of daily living and thus lowers their functional independence and quality of life (Steward and Cramer, 2013). One primary function of the hand is gripping and manipulating objects for activities of daily living. Biomechanically, secure grip of objects can be hindered by abnormally directed grip force post stroke (Seo et al., 2015). The objective of this study was to investigate the neural origin of the impaired grip force direction control post stroke.
Methods:
Three studies were conducted. First, the role of the sensorimotor integration was investigated using short-latency afferent inhibition (SAI) which represents the responsiveness of the primary motor cortex to somatosensory input (Ackerley et al. 2014). SAI was quantified as the extent to which the motor evoked potential (MEP) induced by transcranial magnetic stimulation (TMS) applied to the primary motor cortex of the lesioned hemisphere is suppressed by preceding electrical sensory stimulation targeting the median nerve in the wrist of the affected hand. The association between SAI and grip force direction control in the paretic hand was investigated in 10 chronic stroke survivors. In two additional studies, the role of structural connectivity and the role of functional neural connectivity within the brain's sensorimotor network were investigated using diffusion tensor imaging (DTI) in 22 chronic stroke survivors and using electroencephalography (EEG) in 12 chronic stroke survivors, respectively. The association between structural connectivity and grip force direction control as well as the association between functional connectivity and grip force direction control were investigated, with the lesion volume (measured from brain MRI) accounted for as a covariate.
Results:
The poor performance in grip force direction control in stroke survivors was associated with less SAI (r = 0.63). In addition, the poor performance in grip force direction control was associated with the lower structural connectivity in the network involving bilateral Rolandic, ipsilesional SMA, and contralesional thalamus (r = -0.34) (Schranz et al. 2023). It was also associated with lower functional neural connectivity between the premotor and primary somatosensory cortices of the non-lesioned hemisphere in the alpha frequency band (r = -0.57) (Baker et al., 2023).
Conclusions:
Impaired performance in grip force direction control in the hand affected by a stroke may be manifested as a result of impaired sensorimotor integration as measured by SAI. We postulate that the performance may be facilitated by utilizing the residual neural resources including the unaffected hemisphere. This study contributes to improved understanding of neural mechanisms behind impaired hand function post stroke. This knowledge is expected to pave the way for development of novel treatments. For example, future studies may examine if SAI or cortical functional connectivity could be reinforced via novel interventions such as repetitive brain stimulation targeting the SAI pathway or the unimpaired sensorimotor network in conjunction with targeted hand rehabilitation therapy. Such development of novel treatments may address the impaired grip force direction and thus improve stroke survivors' hand grip function.
Brain Stimulation:
TMS
Motor Behavior:
Motor Behavior Other 1
Novel Imaging Acquisition Methods:
Diffusion MRI
EEG
Physiology, Metabolism and Neurotransmission :
Neurophysiology of Imaging Signals 2
Keywords:
Electroencephaolography (EEG)
Motor
Movement Disorder
Neurological
Peripheral Nerve
Physical Therapy
Somatosensory
Source Localization
Transcranial Magnetic Stimulation (TMS)
WHITE MATTER IMAGING - DTI, HARDI, DSI, ETC
1|2Indicates the priority used for review
Provide references using author date format
Ackerley SJ, Stinear CM, Barber PA, Byblow WD (2014). Priming sensorimotor cortex to enhance task-specific training after subcortical stroke. Clinical Neurophysiology, vol. 125, pp. 1451-1458.
Baker A, Schranz C, Seo NJ (2023). Associating Functional Neural Connectivity and Specific Aspects of Sensorimotor Control in Chronic Stroke. Sensors, vol. 23, no. 12, pp. 5398.
Lawrence ES, Coshall C, Dundas R, Stewart J, Rudd AG, Howard R, Wolfe CDA (2001). Estimates of the Prevalence of Acute Stroke Impairments and Disability in a Multiethnic Population. Stroke, vol. 32, pp. 1279–1284.
Schranz C, Srivastava S, Seamon BA, Marebwa B, Bonilha L, Ramakrishnan V, Wilmskoetter J, Neptune RR, Kautz S, Seo NJ (2023). Different aspects of hand grip performance associated with structural connectivity of distinct sensorimotor networks in chronic stroke. Physiological Reports, vol. 11, no. 7, pp. e15659.
Seo NJ, Enders LR, Motawar B, Kosmopoulos ML, Fathi-Firoozabad M (2015). The extent of altered digit force direction correlates with clinical upper extremity impairment in chronic stroke survivors. Journal of Biomechanics, vol. 48, pp. 383-387.
Stewart JC, Cramer SC (2013). Patient-reported measures provide unique insights into motor function after stroke. Stroke, vol. 44, pp. 1111-1116.