The Effects of Anticonvulsants on Neurological Recovery After Spinal Cord Injury
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THE EFFECTS OF ANTICONVULSANTS ON NEUROLOGICAL RECOVERY AFTER SPINAL CORD INJURY by Freda Warner B.Sc., University of Guelph, 2011 M.P.H., Simon Fraser University, 2015 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in The Faculty of Graduate and Postdoctoral Studies (Kinesiology) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) September 2019 © Freda Warner, 2019 The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: The effects of anticonvulsants on neurological recovery after spinal cord injury Submitted by Freda Warner in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Kinesiology Examining Committee: John Kramer, Kinesiology Supervisor Tania Lam, Kinesiology Supervisory Committee Member Supervisory Committee Member Roanne Preston, Anesthesiology, Pharmacology and Therapeutics University Examiner Thomas Oxland, Mechanical Engineering University Examiner Additional Supervisory Committee Members: Supervisory Committee Member Supervisory Committee Member ii Abstract Spinal cord injury is a devastating neurological condition that results in varying degrees of sensory and motor loss, along with other health complications. Neurological recovery after spinal cord injury is generally thought to be limited to the 6-9 month period after injury, and there are currently no approved pharmacological interventions to improve this recovery. Overlapping with a proposed “window of opportunity” for interventions, neuropathic pain can occur early after injury and necessitate pharmacological management. Among the management options, anticonvulsants are routinely administered. Utilizing longitudinal observational human spinal cord injury data, this thesis explored the effects of anticonvulsants on neurological recovery after spinal cord injury using mixed effects regression, and conduct a meta-analysis on the acute progression of neuropathic pain. The research studies within this thesis are bookended by an introduction and methodology section (Chapters 1 and 2) and the discussion (Chapter 7). In Chapter 3, I examined the effect of anticonvulsants and found a beneficial association with motor recovery contingent on administration at 4 weeks. A review of patient records revealed that the majority of anticonvulsants being administered were gabapentinoids (i.e. pregabalin and gabapentin). To further examine whether this effect was specific to gabapentinoids or obtained by all anticonvulsants, Chapter 4 examined a unique spinal cord injured population administered non-gabapentinoid anticonvulsants and found no statistically significant associations with neurological recovery. Chapter 5 included a chart review to examine the effect of gabapentinoid-specific administration, and found a continued beneficial association with motor score, as well as the sensory outcome of light touch. Further, this chapter identified that very early administration (e.g. within 5 days) was necessary to achieve the largest benefit. Finally, Chapter 6 produced a longitudinal framework of neuropathic pain progression in clinical trials. In short, this thesis presents novel findings regarding the administration of anticonvulsants after spinal cord injury, and the beneficial association of gabapentinoid- specific anticonvulsants on motor recovery. Further, it provides an advance in our iii understanding of neuropathic pain progression after injury and a framework to guide future clinical trials. iv Lay summary Spinal cord injuries can result in a loss of sensation and movement. After injury there is usually an initial period of neurological recovery (i.e. recovery of movement and sensation), after which these impairments are permanent. There are currently no approved drugs that can help maximize this neurological recovery after injury. Anticonvulsants, including gabapentinoids, are drugs that are commonly administered after spinal cord injury for complications including neuropathic pain and seizures. Using human spinal cord injury cohort and registry data, I examined the effects of anticonvulsants on neurological recovery after spinal cord injury. Through secondary data analysis I identified that the early administration of gabapentinoid-specific anticonvulsants (and not anticonvulsants in general) was associated with an improvement in recovery. I also describe the progression of neuropathic pain after injury, with the goal of informing future clinical trials. v Preface A version of Chapter 1 is a published book chapter [Warner FM, Cragg J, Steeves JC, Kramer JLK. “Clinical trials and spinal cord injury: Challenges and therapeutic interventions.” In Neurological Aspects of Spinal Cord Injury. Springer, 2017]. I was the lead investigator, responsible for concept formation and all major manuscript composition. Cragg J, Steeves JC, and Kramer JLK were also responsible for concept formation and manuscript edits. Kramer JLK was the supervisory author on this project. A version of Chapter 3 has been published in Cell Reports [Warner FM, Cragg JJ, Jutzeler CR, Röhrich F, Weidner N, Saur M, Maier DD, Schuld C, EMSCI Study Group, Curt A, Kramer JK. Early administration of gabapentinoids improves motor recovery after human spinal cord injury. Cell Reports 2017; 18:1614-1618]. Cragg JJ, Jutzeler CR, Röhrich F, Weidner N, Saur M, Maier DD, Schuld C, and Curt A contributed to concept formation and manuscript edits. EMSCI Study Group was responsible for data collection. Kramer JK was the supervisory author on this project and was involved in concept formation and manuscript edits. I was involved in concept formation and responsible for all analytical methods, data analysis, and manuscript composition. A version of Chapter 4 has been published in CNS Drugs [Warner FM, Jutzeler CR, Cragg JJ, Tong B, Grassner L, Bradke F, Geisler F, Kramer JK. The effect of non- gabapentinoid anitconvulsants on sensorimotor recovery after spinal cord injury. CNS Drugs 2019; 33(5):503-511]. Jutzeler CR and Cragg JJ contributed to concept formation and manuscript edits. Geisler F was responsible for the data collection and manuscript edits. Tong B, Grassner L, and Bradke F were responsible for content and manuscript edits. Kramer JK was the supervisory author on this project and was involved in concept formation and manuscript edits. I was involved in concept formation and responsible for all analytical methods, data analysis, and manuscript composition. In Chapter 5, Cragg JJ, Jutzeler CR, Maier D, and Curt A contributed to concept formation and chapter edits. Grassner L, Mach O, Curt A and the EMSCI Study Group were responsible for data collection and chapter edits. Kramer JK was the supervisory author on this project and was involved in concept formation and chapter edits. I was involved in concept formation and responsible for all analytical methods, data analysis, and chapter composition. A version of Chapter 6 has been published in the Journal of Neurotrauma [Warner FM, Cragg JJ, Jutzeler CR, Finnerup NB, Weargen L, Weidner N, Maier D, Kalke Y-B, Curt A, Kramer JK. Progression of neuropathic pain after acute spinal cord injury: a meta- analysis and framework for clinical trials. Journal of Neurotrauma 2019; 1-8]. Jutzeler CR, and Cragg JJ contributed to concept formation and manuscript edits. Finnerup NB, Weargen L, Weidner N, Maier D, Kalke Y-B, Curt A and the EMSCI sites were responsible for data collection and manuscript edits. Kramer JK was the supervisory author on this project and was involved in concept formation and manuscript edits. I was involved in concept formation and responsible for all analytical methods, data analysis, and manuscript composition. Ethics approvals for the studies contained in this thesis were obtained by the University of British Columbia’s Research Ethics board (certificates #H16-01119 and H16-03143). vi Table of contents Abstract ................................................................................................................ iii Lay summary ........................................................................................................ v Preface ................................................................................................................ vi Table of contents ................................................................................................ vii List of tables .......................................................................................................... x List of figures....................................................................................................... xii List of abbreviations ............................................................................................ xiii Acknowledgements ............................................................................................ xiv Chapter 1 Introduction .......................................................................................... 1 1.1 Overview: the search for acute interventions to improve neurological outcomes for individuals with spinal cord injuries .............................................. 1 1.2 Challenges of spinal cord injury trials .......................................................... 1 1.2.1 A “moving target”: effect of the natural progression of spinal cord injury ....................................................................................................................... 2 1.2.2 Low numbers