Systemic and Cerebral Hemodynamic Contribution to Cognitive Performance in Spinal Cord Injury

Cognitive deficits are prevalent in the spinal cord injury (SCI) population, and consensus suggests that concomitant traumatic brain injury or comorbid conditions are primarily responsible for these deficits. However, mounting evidence supports the possibility that systemic and cerebral hemodynamic dysfunction may contribute to the cognitive deficits reported in persons with SCI. We sought to determine the contribution of changes in blood pressure (BP) and changes in cerebral blood flow velocity (CBFv) to test performance on the Symbol Digit Modalities Test (SDMT) in persons with SCI compared with matched non-SCI controls. Participants included 36 non-SCI controls and 67 persons with SCI: 33 with paraplegia (T2-T12) and 34 with tetraplegia (C3-T1). Continuous beat-to-beat BP and simultaneous CBFv was monitored for 5 min during seated rest and during the SDMT, which assesses information processing speed, sustained attention, and visual working memory. The results indicate significantly lower SDMT scores in the group with tetraplegia (44 ± 10) compared to the non-SCI controls (53 ± 14; p