Essay Example on SCI Mechanism and Pathophysiology

The potentially devastating consequences of SCI can include major dysfunction to the motor sensory and autonomic systems Appropriate pre hospital management and consideration of the mechanism of injury can significantly improve outcomes in patients with SCI Mechanism and Pathophysiology SCI is usually caused when two or more vertebrae have an unstable fracture but can also be caused by ruptured ligaments allowing movement of the vertebra to damage the spinal cord without an actual fracture Marsland and Kapoor 2008 127 Blunt trauma to the head and neck is the most common cause of fracture or ligament rupture 50 80 of SCI result from a hyperflexion rotation injury Cole 2009 SCI can occur both in isolation or with other injuries Hess et al 2016 However it only presents in 2 6 of trauma patients although this figure doubles in patients with a head injury and trebles in those with decreased level of consciousness Milby et al 2008 Halpern et al 2010 

A SCI can be complete or incomplete In a complete spinal injury sensation and motor function below the point of injury are lost whether or not the spinal cord is severed Bledsoe and Benner 2006 394 In an incomplete SCI full or partial motor or sensory function are preserved below the level of injury Wyatt et al 2012 369 A patient's level of injury is defined as the lowest level of full sensation and function Greaves and Porter 2007 282 Paraplegia occurs when the legs are affected by spinal cord damage in thoracic lumbar or sacral injuries and tetraplegia occurs when all four limbs are affected as a direct result of cervical spine damage Douglas et al 2013 260 As spinal nerve tissue is very similar to brain tissue the nature of injuries are comparable Spinal nerve tissue can be concussed bruised and suffer cell death It can also be subject to compression and swelling Bledsloe and Benner 2006 394 Serious SCI result in a high percentage of permanent damage with poor outcomes for the patient's quality of life Dixon et al 2014

The two main results of SCI are spinal shock and neurogenic shock In spinal shock the symptoms are similar to neurogenic shock but are temporary and include loss of motor and sensory function Unlike neurogenic shock haemodynamic function is not directly affected Bledsloe and Benner 2006 395 In neurogenic shock the sympathetic nervous system is compromised This results in parasympathetic nervous system stimulation without any regulation from the sympathetic nervous system Axelrad et al 2013 Neurogenic shock is not to be confused with spinal shock which is not circulatory in nature In neurogenic shock the body loses its ability to activate the sympathetic nervous system With the loss of sympathetic stimulation to the blood vessels there is no vasoconstriction which results in a sudden decrease in blood pressure Bledsloe and Benner 2006 395 Neurogenic shock results from spinal cord damage above the level of the sixth thoracic vertebra and occurs within the first twenty four hours of injury and can last beyond three weeks If the injury is below the fifth cervical vertebra the patient will present with diaphragmatic breathing due to loss of nervous control of the intercostal muscles however if the injury is above the third cervical vertebra the patient will deteriorate into respiratory arrest immediately post injury due to loss of nervous control of the diaphragm Bradycardia may also result from lack of sympathetic stimulation to the myocardium Paramedic management in this case would support the use of Atropine to reverse the bradycardia JR Calc guidelines 2016 Immobilisation 

Theory The potential risk of missing a life changing SCI in the prehospital field has cultivated a practice of presuming SCI until ruled out once the patient has been conveyed to hospital Nutbeam and Boyland 2013 Marsland and Kapoor 2008 129 Abram and Bulstrode 2009 Wyatt et al 2012 378 The practice of immobilizing fractured bones with a splint has also prompted the use of triple immobilization which involves strapping the patient to a rigid board or mattress immobilising their neck with a stiff collar and securing their head with foam blocks Bledsoe and Faaem 2013 Current ambulance service guidelines advocate prompt spinal immobilisation while the primary assessment is undertaken with a heavy emphasis on the mechanism of injury Fisher et al 2013 228 UK Ambulance Services Clinical Practice Guidelines 2016 There are currently two decision making tools in use the Canadian C Spine Rules CCR and the National Emergency X Radiography Utilization Study NEXUS Michaleff et al 2012 UK ambulance services use protocols that are based on both tools However the purpose of these two tools was not to reduce spinal immobilization but to reduce the need for x ray to rule out a c spine injury in the hospital setting Therefore the threshold for a positive test with both tools is very low and has helped drive pre hospital culture for routine immobilization Vaillancourt et a 2011 Distracting Injuries 

A separate injury which is sufficient to interfere with the assessment of a patient's c spine is regarded as a distracting injury in UK ambulance guidelines for spinal immobilisation and features in the NEXUS guidelines Fisher et al 2013 Michaleff et al 2012 There is no evidence to support this with some studies casting doubt on distracting injuries by showing that even major limb injury does not distract from c spine tenderness Cason et al 2016 Dahlquist et al 2015 Although adrenaline can mask pain it's short effect is well known and pain will usually return within 10 minutes of the injury Grossman and Christensen 2008 Grange and Cotton 2004 We never apply the distracting injury rule to any other part of the body except the c spine which casts further doubt on its validity If the patient is alert and compliant a thorough physical assessment using established principles will identify a potential c spine injury even in the presence of a distracting injury Purcell 2013 75 Rose et al 2012