Investigation of robotics-assisted tilt-table therapy for early-stage rehabilitation in spinal cord injury

This article provides the outcome of an investigation of robotics-assisted tilt-table therapy for early-stage rehabilitation in spinal cord injur

Development and evaluation of rehabilitation technologies for early-stage spinal cord injury

Exercise is fundamental to a return to normal living after a Spinal Cord Injury (SCI) but is complicated by a rapid decline in function and fitness immediately following the injury. In addition to muscle paralysis, Orthostatic Hypotension (OH), a decline in cardiopulmonary and vascular fitness, extensive muscle atrophy and bone demineralization each contribute to an inability to carry out effective forms of exercise. Suitable rehabilitation technologies are central to overcoming these complications and to facilitate recovery. The aim of the work presented in this thesis was to identify technologies which may be used for exercise during SCI rehabilitation, with a focus on early-stage SCI patients at the beginning of the rehabilitation process. Two such technologies were identified and investigated: Robotic Assisted Tilt Table Therapy (RATTT) and Whole Body Vibration (WBV). The suitability of these technologies was evaluated by measuring the acute physiological responses of SCI patients during intensive use of these systems. Robotic Assisted Tilt Table Therapy is primarily used to treat OH in stroke and SCI patients. However, the potential therapeutic effect of RATTT as an exercise modality has so far not been investigated. An investigation into the physiological responses of early-stage SCI patients during intensive RATTT stepping was therefore carried out. The intention was to determine whether RATTT may potentially be used for the combined purpose of increasing orthostatic tolerance, improving cardiopulmonary fitness and improving vascular health. RATTT is particularly suited to early-stage rehabilitation because orthostatic tolerance is not a prerequisite for its use. Three motor-complete and three motor-incomplete early- stage SCI patients were recruited from the Queen Elizabeth National Spinal Injuries Unit (QENSIU) in Glasgow to participate in this cross-sectional study. The cardiopulmonary and vascular responses to different RATTT stepping conditions, including the combination of RATTT stepping with Functional Electrical Stimulation (FES), were investigated. Increases in oxygen uptake, respiratory exchange ratio, minute ventilation and heart rate were found for both motor-incomplete and motor-complete SCI participants. The responses were largest for the motor-incomplete volunteers with Metabolic Equivalent (MET) values between 1.5 - 3.1. These results confirmed that RATTT can be used as an exercise modality during early- stage SCI rehabilitation. Whole Body Vibration was initially developed and commercialised for application during exercise in a general population with no neurological deficit, and while the physiological mechanisms which underly the response to WBV are still relatively poorly understood, current research suggests that WBV may lead to increases in muscle strength, power, bone mineral density and flexibility. It is hypothesised that the neuromuscular response to WBV is achieved through reflex activity, though the specific neural pathway is broadly debated. Nonetheless, an increase in neuromuscular activity duringWBV has been confirmed, suggesting that it may potentially be used to increase muscle mass, strength and power, and therefore counteract muscle atrophy and bone demineralization in SCI. However, little is known about the neuromuscular response of SCI patients to WBV, and it is not clear how to best administer WBV to this patient group or which vibration parameters should be applied. A WBV platform was therefore integrated with a partial Body Weight Support (pBWS) system in order to investigate the application of WBV during SCI rehabilitation. The feasibility of this approach was determined in the first instance in experiments with participants from a general population with no neurological deficit, followed by an evaluation with a SCI population. The aim was to determine if the stimulus from WBV applied in conjunction with pBWS was sufficient to elicit an increased neuromuscular response, and if so, to characterise the magnitudes and trends of the responses. Ten participants with no neurological deficit were recruited to investigate the feasibility of WBV-pBWS and to establish a normative data set with which to compare the results from 14 SCI participants recruited from QENSIU. The main factors under investigation were vibration frequency, vibration amplitude, level of pBWS, muscle group and classification of SCI. It was shown that WBV did elicit an increase in neuromuscular activity and that the magnitude of the response could be moderated by vibration frequency, vibration amplitude and level of pBWS. Average changes relative to baseline measurements were up to 71% for the neurologically intact participants, and between 44% to 66% for the SCI participants depending on classification of injury. Neuromuscular activity was characteristic for each muscle group and the characteristic was principally moderated by the proximity of the muscle to the WBV platform and peak platform acceleration. Despite the relatively large change in neuromuscular activity when compared to baseline, the absolute changes in activity were relatively small and likely to be of insufficient magnitude to result in muscle hypertrophy. Results from this study indicated that WBV was of sufficient intensity to elicit a response from the �-motoneuron but of insufficient intensity to increase muscle strength. Based on this, the potential use of WBV as a non-pharmacological treatment of spasm was identified by stimulating part of the neural pathway upon which spasm acts and therefore provide a mechanism to moderate the threshold for spasm, without the risk of increasing muscle strength and therefore potential for injury during a spastic episode. In summary, this thesis presents RATTT and WBV-pBWS as two modalities suitable for use in early-stage SCI rehabilitation. While RATTT can elicit substantial cardiopulmonary responses in this patient group, the evaluation of WBV showed limited effects on muscle activation, but suggested potential application in the treatment of spasticity

A Plio-Pleistocene sediment wedge on the continental shelf west of central Ireland: The Connemara Fan

Glacigenic sediment fans recording shelf edge deposition from marine-terminating ice sheets have previously been recognised along the NW European continental margin from Svalbard to as far south as Donegal, off north-west Ireland. Here we present evidence of a previously unrecognised partially glacially-fed Plio-Pleistocene sediment wedge on the continental shelf west of central Ireland using 2D and 3D seismic reflection data correlated to a commercial borehole. The ‘Connemara Fan’ covers a shelf area of approximately 9000 km2 in water depths of 125–310 m, extending westwards into the Porcupine Seabight from the Irish Mainland Shelf. The wedge comprises up to 160 m of sediment that culminates in a prominent moraininc ridge at seabed and contains two discordant reflection surfaces (R1 and 2) that subdivide it into three seismic units (SU1–3). Stratigraphic boreholes 27/24-2 and 2A located on the inner shelf show that the lower unit (SU1) is composed of Pliocene marine sediments, while SU2 and 3 comprise glacially influenced facies of Quaternary age. Extracts from a 3D seismic data volume within the central part of the fan show channels within the Pliocene succession, while iceberg scours are observed on the R1 and R2 reflectors. The Connemara Fan is inferred to record sediment supply from central western Ireland, with Quaternary units probably recording at least two glacial advance-retreat cycles with ice sheets repeatedly grounding across the inner (Irish Mainland) shelf. Our findings extend the range of glacially-influenced grounding line depocentres southwards along the NW European continental margin

Virtual Ontogeny of Cortical Growth Preceding Mental Illness

Background: Morphology of the human cerebral cortex differs across psychiatric disorders, with neurobiology and developmental origins mostly undetermined. Deviations in the tangential growth of the cerebral cortex during pre/perinatal periods may be reflected in individual variations in cortical surface area later in life. Methods: Interregional profiles of group differences in surface area between cases and controls were generated using T1-weighted magnetic resonance imaging from 27,359 individuals including those with attention-deficit/hyperactivity disorder, autism spectrum disorder, bipolar disorder, major depressive disorder, schizophrenia, and high general psychopathology (through the Child Behavior Checklist). Similarity of interregional profiles of group differences in surface area and prenatal cell-specific gene expression was assessed. Results: Across the 11 cortical regions, group differences in cortical area for attention-deficit/hyperactivity disorder, schizophrenia, and Child Behavior Checklist were dominant in multimodal association cortices. The same interregional profiles were also associated with interregional profiles of (prenatal) gene expression specific to proliferative cells, namely radial glia and intermediate progenitor cells (greater expression, larger difference), as well as differentiated cells, namely excitatory neurons and endothelial and mural cells (greater expression, smaller difference). Finally, these cell types were implicated in known pre/perinatal risk factors for psychosis. Genes coexpressed with radial glia were enriched with genes implicated in congenital abnormalities, birth weight, hypoxia, and starvation. Genes coexpressed with endothelial and mural genes were enriched with genes associated with maternal hypertension and preterm birth. Conclusions: Our findings support a neurodevelopmental model of vulnerability to mental illness whereby prenatal risk factors acting through cell-specific processes lead to deviations from typical brain development during pregnancy