The Glasgow Coma Scale (GCS) Evidence based practice Sophie Porter 3rd year Kingston University Student Studying a Bachelors with honours in nursing
Introduction to the GCS • Neurological assessment tool • Published in 1974 by Jennett and Teasdale • Aim of the tool: determining the severity of a patients’ brain dysfunction • Originally intended for post head injury patients, now a tool for all acute medical and trauma patients. • It is widely used to assess level of consciousness in a variety of clinical settings and is a recommended observation tool in all patients with head injuries (NICE, 2007)
Scoring system • A patients assessment will result in a score between three; no response and fifteen; fully alert and responsive (Jevon, 2008) • The score out of 15 is derived from the three tests on eye opening, verbal response and motor response. Alongside this, pupil response, neurological limb response and basic vital signs are also recorded (Fairley et al, 2005).
How are the components assessed? (Jevon, 2008) • Eyes Opening: • Score 4: eyes open spontaneously; • Score 3: eyes open to speech; • Score 2: eyes open in response to pain only, for example trapezium squeeze (caution if applying a painful stimulus); • Score 1: eyes do not open to verbal or painful stimuli. • ‘C’ is recorded for patients unable to open eyes due to for example swelling
How are the components assessed?(Jevon, 2008) • Verbal Response: • Score 5: orientated; must be able to tell you their full name, the place in which they are and the date. If the patient doesn’t know any of these it is assumed they are confused. • Score 4: confused; not able to answer orientation questions • Score 3: inappropriate words; swearing, aggression, unrelated words to the questions being asked • Score 2: incomprehensible sounds; • Score 1: no verbal response. • ‘D’ is marked for patients who are dysphasic (unable to speak coherently. ‘T’ is marked for those with a tracheostomy
How are the components assessed?(Jevon, 2008) Best Motor Response: • Score 6: obeys commands. The patient can perform two different movements; primative reflexes should not be tested • Score 5: localises to central pain. The patient does not respond to a verbal stimulus but purposely moves an arm to remove the cause of a central painful stimulus • Score 4: normal flexion. The patient flexes or bends the arm towards the source of the pain but fails to locate the source of the pain (no wrist rotation) • Score 3: abnormal flexion to pain(see picture) • Score 2: extension to pain(see picture) • Score 1: no response to painful stimuli.
Eye Opening Validity • Neurone collection in the brain stem, hypothalamus and thalamus Reticular Activation System (RAS) • RAS is the centre responsible for generating the eye opening response (Tortora and Grabowski, 2003, p. 462) • Increased stimuli = impairment of RAS • May be due to direct trauma or a rise in Intracranial pressure (ICP) (Hickey, 1997, p.156) • A rise in I.C.P can indicate lesions within the cranium or can be due to a disorder in the circulation of cerebral spinal fluid. Headaches, nausea, vomiting and visual problems are all symptomatic of increased I.C.P (Dunn, 2002).
Verbal Response Validity • Determines the level of awareness patients have of their environment (Richards and Edwards, 2003, p.32) • Temporal lobe of the cerebral cortex: controls a persons’ ability to percept their environment and access their long and short term memory (Waterhouse, 2009, p.210) • Confusion, memory loss and inability to compose sentences could be an indication of damage or abnormalities in the temporal lobe. (Yonelinas et al¸ 2002, p.1236) • This damage, causing increased pressure on the cranium, could include; haemorrhaging, tumours, fluid around the brain (hydrocephalus), infection i.e. meningitis, or swelling of the brain matter itself (Bradley et al, 2008). • Of course there are other reasons which may cause confusion...
Best Motor Response Validity • How well a patient can respond to simple commands, recording the best limb. • Good indication of how well the brain is functioning as a whole (Edwards, 2001, p.95) • In particular the primary motor and sensory cortex (Waterhouse, 2009, p.210) these areas allow us to generate voluntary movement (Marieb, 2001, p. 436-437) • Difficult to understand what deterioration in this component would indicate without more extensive investigations • Lack of clarity questions the components validity
Reliability of components: factors • Differences between application of stimulus • Sedation- causes decreased arousal • No considerations for neurological diseases i.e. dementia • Medication side effects – delirium • Untrained healthcare practioner: inter-user reliability • Broken limbs etc
References • NICE (2007) Head Injury: Triage, Assessment, Investigation and Early Management of Head Injury in Infants, Children and Adults. [Online]. Available at: http://www.nice.org.uk (Accessed: 12 February 2012). • Jevon, P. (2008) ‘Neurological assessment part 2- pupillary assessment’, Nursing Times, 104, July [Online]. Available at: http://www.nursingtimes.net/Binaries/0-4-1/4-1710333.pdf (Accessed: 15 February 2012). • Fairley, D., Timothy, J. and Cosgrove, J. (2005) ‘Using a coma scale to assess patient consciousness levels’, Nursing Times, 101, June [Online]. Available at: http://www.nursingtimes.net/nursing-practice-clinical-research/using-a-coma-scale-to-assess-patient-consciousness-levels/203819.article (Accessed: 15 February 2012). • Yonelinas, P., Kroll, N.E.A., Quamme, J.R., Lazzara, M.M., Suave, M.J., Widaman, K.F. and Knight, R.T.(2002) ‘Effects of extensive temporal lobe damage or mild hypoxia on recollection and familiarity’, Nature Neuroscience, 5, November [Online]. Available at: http://psychology.ucdavis.edu/labs/Widaman/mypdfs/wid111.pdf (Accessed: 22 February 2012). • Waterhouse, C. (2009) ‘The use of painful stimulus in relation to Glasgow Coma Scale observations’, British Journal of Neuroscience Nursing, 5(5), pp. 209-215 • Tortora, G.J. and Grabowski, S.R. (2003) Principles of anatomy and physiology. 10thedn. USA: John Wiley and Sons, Inc • Hickey, J.V. (1997) The clinical practice of Neurological and Neurosurgical Nursing. 4th edn. New York: JB Lippincott.