Sleep, obstructive sleep apnoea and neuropsychological function in acute quadriplegia

Obstructive sleep apnoea (OSA) is highly prevalent following spinal cord injury (SCI) and is likely caused by the injury. Beyond the devastating physical consequences of SCI, neuropsychological dysfunction is also common. OSA is known to impair many areas of neuropsychological function in both the able-bodied and chronic SCI patients. However, this has not been investigated in patients with acute SCI. The aim of this thesis was to investigate the relationship between OSA severity and neuropsychological function in patients with acute quadriplegia and OSA. To investigate this aim, participants underwent overnight polysomnography (PSG) and neuropsychological testing. Two methodological experiments were firstly carried out to ensure the accuracy and interpretability of the PSG data collected. Ambulatory PSG was conducted on spinal wards acutely, to ensure as little disruption to the patients’ care as possible. A limitation of ambulatory PSG is the inability to measure light level and calculate total dark time, the denominator for several important sleep indices. The usefulness of a prototype light sensor (LS) was investigated for use in ambulatory PSG, where light is uncontrolled and the LS is uncalibrated for use across varied settings. The LS was found to be apt and useful, particularly in patients with acute quadriplegia, where the nearest surrogate marker of the time of lights out, change from upright to lying position, was clinically irrelevant in this group who were commonly lying in bed prior to lights out. Given the results of this first experiment, the LS was implemented when investigating the primary study aims. A second methodological experiment was carried out to quantify the effect of a change in the rules for sleep staging and respiratory scoring which occurred following study commencement. This has previously been examined for other patient groups but not for patients with quadriplegia where the pathogenesis of OSA and respiratory event presentation may