Epidural Stimulation May Benefit Cardiovascular Function in Spinal Cord Injury

The use of epidural neuroprosthetics appears to be a feasible approach for the management of cardiovascular (CV) dysfunction among persons with chronic spinal cord injury (SCI), offering an important complement to often slow-acting pharmacotherapeutic agents, according to the results of a case study published in JAMA Neurology.

The individual evaluated, who was in his early 30s, had a chronic C5 motor-complete SCI. The patient had been fitted with an epidural spinal cord stimulation unit and 16-electrode array at T11-L1 vertebral levels 12 months earlier.

The investigators conducted a series of tests during a 2-week period to establish the optimal stimulation parameters for increasing blood pressure (BP) in the seated position, with a wide-field stimulation configuration eventually selected. On the main experimental day, they carried out the following assessments: beat-by-beat BP via finger photoplethysmography corrected to brachial BP, cardiac function using transthoracic echocardiography, cerebral blood flow/neurovascular coupling via transcranial Doppler, and trunk/lower limb electromyography.

All the procedures were initially evaluated in the supine position and then in response to a 60°

head-up tilt, with or without epidural stimulation. To confirm the reliability of their findings, the researchers reassessed the BP response to a 60° head-up tilt, with and without stimulation, on 3 separate days.

Use of the stimulation resolved the patient’s orthostatic hypotension, which is prevalent and quite debilitating among individuals with SCI.² The increase in the patient’s BP in response to stimulation was well-controlled. Regarding brain findings, the use of stimulation prevented the orthostatic-induced 30% decrease in middle cerebral artery blood flow, improved neurovascular coupling, and resolved such orthostatic BP-induced symptoms as lightheadedness, dizziness, and poor concentration. Use of the epidural stimulation also prevented reduction in cardiac filling, thus preserving stroke volume and cardiac output.

This study is the first of its kind to demonstrate the acute cardiovascular benefits of epidural stimulation in a person with SCI, which involved the systemic vasculature, heart, and brain. The incorporation of this approach could provide an important addition to the use of pharmacologic agents, which are often slow-acting and associated with adverse effects, in this population.

References

1. West CR, Phillips AA, Squair JW, et al. Association of epidural stimulation with cardiovascular function in an individual with spinal cord injury [published online February 19, 2018]. JAMA Neurol. doi: 10.1001/jamaneurol.2017.5055
2. Claydon VE, Krassioukov AV. Orthostatic hypotension and autonomic pathways after spinal cord injury. J Neurotrauma. 2006;23(12):1713-1725