Optical Monitoring and Detection of Spinal Cord Ischemia

Abstract

Spinal cord ischemia can lead to paralysis or paraparesis, but if detected early it may be amenable to treatment. Current methods use evoked potentials for detection of spinal cord ischemia, a decades old technology whose warning signs are indirect and significantly delayed from the onset of ischemia. Here we introduce and demonstrate a prototype fiber optic device that directly measures spinal cord blood flow and oxygenation. This technical advance in neurological monitoring promises a new standard of care for detection of spinal cord ischemia and the opportunity for early intervention. We demonstrate the probe in an adult Dorset sheep model. Both open and percutaneous approaches were evaluated during pharmacologic, physiological, and mechanical interventions designed to induce variations in spinal cord blood flow and oxygenation. The induced variations were rapidly and reproducibly detected, demonstrating direct measurement of spinal cord ischemia in real-time. In the future, this form of hemodynamic spinal cord diagnosis could significantly improve monitoring and management in a broad range of patients, including those undergoing thoracic and abdominal aortic revascularization, spine stabilization procedures for scoliosis and trauma, spinal cord tumor resection, and those requiring management of spinal cord injury in intensive care settings.

Fiber-optic Monitoring of Spinal Cord Hemodynamics in Experimental Aortic Occlusion

“…The monitor, which collects blood flow (DCS) and oxygenation (DOS) data, is composed of two modules as described previously 17 . Briefly, the DCS module uses a long-coherent, continuous-wave 785 nm laser (CrystaLaser Inc., NV) as a light source.…”

“…We have developed a near-infrared optical device that can accurately monitor and immediately detect the occurrence of spinal cord ischemia 17 . The device is based on the principles of Diffuse Correlation Spectroscopy (DCS) and Diffuse Optical Spectroscopy (DOS), which have previously been employed successfully in research to measure cerebral hemodynamics, in cancer diagnostics, and muscle perfusion studies 18,19 .…”

Diffuse correlation spectroscopy for measurement of cerebral blood flow: future prospects

“…3). In addition, DCS has been used to detect acute spinal cord ischemia in sheep models, 44 to assess CBF changes due to vocal stuttering, 45 and to elucidate the effects of normal aging on posture manipulations. 46 Per new therapeutics, DCS has been used to characterize the cerebral hemodynamic responses due to transcranial magnetic stimulation (TMS) in an effort to elucidate the mechanisms of TMS.…”

Spinal cord autoregulation using near-infrared spectroscopy under normal, hypovolemic, and post-fluid resuscitation conditions in a swine model: a comparison with cerebral autoregulation

“…NIRS estimates mixed tissue hemoglobin oxygen saturation levels of the arterial, venous, and capillary blood within the field of view [10,11], which allows the oxygen supply-and-demand balance to be evaluated under differing conditions. Similar to what has been done with the cerebrum, several studies have measured spinal cord oxygenation using NIRS directly [12][13][14][15] (via surgical procedure or thin fiber-optic probe placed in the intrathecal or epidural space) or indirectly [16][17][18][19] (via paraspinal muscle oxygenation monitoring, based on the paraspinal collateral network concept) to monitor spinal cord perfusion, but few studies to date have assessed spinal cord autoregulation using this method.…”