Central nervous system organisation following traumatic incomplete spinal cord injury (iSCI) : a longitudinal clinical study

Izzeldin, Isameldin M. H.

Thesis

Central nervous system organisation following traumatic incomplete spinal cord injury (iSCI) : a longitudinal clinical study

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Creator

Izzeldin, Isameldin M. H.

Rights statement

Strathclyde Thesis Copyright

Awarding institution

University of Strathclyde

Date of award

2022

Thesis identifier

T16391

Person Identifier (Local)

200358996

Qualification Level

Doctoral (Postgraduate)

Qualification Name

Doctor of Philosophy (PhD)

Department, School or Faculty

Department of Biomedical Engineering

Abstract

Traumatic spinal cord injury (SCI) triggers pathophysiological consequences and secondary injuries that combine to determine the extent and final outcome of SCI. This study is aimed at examining a set of electrophysiological tests for their potential practicality and accuracy in assessing incomplete SCI and associated clinical presentation. These electrophysiological tests, which are less frequently used in clinical practice, included somatosensory evoked potential (SEP) methods improved with the addition of Dermatomal SEP (D-SEP) and analysis of event related synchronisation (ERS) and desynchronisation (ERD), potentially providing more information about the ascending spinal tracts sub-serving examined sensory modalities. In a manner complementary to this sensory assessment, transcranial magnetic stimulation (TMS) of cerebral cortex was used to assess integrity and function of descending motor cortico-spinal tracts (CST) sub-serving signals from cortical pyramidal neurons to corresponding muscles above and below specified SCI levels. Coupled simultaneous electroencephalography (EEG) and surface electromyography (EMG) from corresponding muscles, Cortico-Muscular Coherence (CMC), was analysed to expose any EEG-EMG synchrony to highlight functional relationships of cerebral motor cortex and target muscles served. Information from sensory and motor spinal tract assessment of 9 SCI patients was charted alongside clinical assessment of neurological function using the American Spinal Injuries Association (ASIA) scale obtaining valid comparative electrophysiological clinical means of longitudinal follow up of any possible improvement or deterioration seen following SCI. Similar electrophysiological assessment was performed for 14 healthy volunteers (normal subjects used as control) obtaining normative data. The resulting data were collected for computational analysis and results obtained on the integrity and function of SCI lesions, as well as trends in electrophysiological measurements. These data also informed ways to predict possible recovery and outcome of SCI. The study faced technical challenges that stood out as limitations to the full potentials.? The electrophysiological tests carried out for SCI patients in acute hospital settings are extremely challenging, raising fundamental questions of how these tests could be brought into the acute clinical setting in the caring for SCI patients. Individual electrophysiological tests included conventional SEP measurements. These were relatively straightforward as part of assessing SCI patients. These include improved SEP measures combined with electrophysiological means of assessing the integrity of peripheral nerves. D-SEPs are generally less reliable than standard mixed-nerve SEPs; however, with the improvements, D-SEP measurements brings useful anatomical detection of level information. For both SEP and D-SEP measurements, reporting of abnormalities might have been enhanced by improving specificity of deciding abnormal results relating to amplitude and latency. Motor Evoked Potentials (MEP) parameters are a reliable electrophysiological measure of motor function, and are used in concordance with the clinical Asia Impairment Scale scores. MEP parameters have a potential relevance to functional outcomes such as hand function and walking following SCI. An area of improvement of MEP includes estimation of central conduction time (CCT) to allow detection of any peripheral nerve abnormality or degeneration affecting MEP measurements. However, the Cortico-Muscular Coherence (CMC) is not easy to obtain due to clinical factors and the use of medications in the context of SCI. CMC however has potential for future improved measures of muscle function in patients with recovering muscle power tested at time intervals. Overall, combining improved SEP and MEP measurements offer better information on sensory and motor function and pathways, respectively. This offers the best chance of obtaining reliable comprehensive information on injured spinal tracts and their recovery process. The study concluded that examined electrophysiological methods of assessing sensory and motor spinal tracts were sensitive, reproducible and accurate. They are reliable for use in assessing SCI patients in an acute hospital setting. This study focussed on the technical challenges facing these electrophysiological methods used in the clinical setting for accurately measurement of outcome or recovery following SCI.

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