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Causes of Acute Neurological Deterioration

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General Practice ( GP ) / Family Medicine
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3 minutes

Early detection of neurological deterioration in patients means interventions are more likely to be successful (CCSO 2015)

Therefore, you must be informed about the possible causes of neurological deterioration, know how to correctly assess the patient and intervene appropriately.

What is Neurological Deterioration?

Neurological deterioration can be defined as a decrease of two or more points on the Glasgow Coma Scale (GCS), which measures a patient’s level of consciousness on a scale of 3 to 15 (Shkirkova et al. 2018).

Patients may present in a variety of consciousness states ranging from full alertness and awareness, to some level of impairment, to complete unawareness and unresponsiveness (Cooksley, Rose & Holland 2018).

A patient with a GCS score of less than eight is considered to be neurologically compromised, which is a medical emergency relying on prompt diagnosis and medical management for a favourable patient outcome (Cooksley, Rose & Holland 2018).


Read: Performing a Neurological Assessment Common Causes of Neurological Deterioration

While a neurological assessment is useful for recognising deterioration, the cause will need to be identified so that the patient can be appropriately treated. The following are some common causes of neurological deterioration:


Sedation-related neurological deterioration may be caused by opiate overdose or anaesthetic that has not been reversed effectively, causing the patient to remain heavily sedated.

The patient may present with:

  • Pinpoint pupils;
  • Respiratory decline or a decrease in respiratory rate. This may cause apnoea, which is a medical emergency;
  • Drowsiness or unresponsiveness (in the case of opiate overdose);
  • Airway obstruction or hypoxia (may occur if an anaesthetic has not been reversed appropriately).

(Vincent et al. 2018; CEC 2013; Schiller et al. 2020)


Neurological deterioration may be caused by a:

  • Ischaemic stroke;
  • Haemorrhagic stroke; or
  • Space-occupying lesion.

The patient’s pupils may appear unequal. A stroke is a medical emergency and requires early intervention.

(Jeffery, Young, Swann & Lueck 2019; Stroke Foundation 2017)


A patient experiencing a seizure may present with mydriasis (dilated pupils) (Kutlu et al. 2014).

In the case of a seizure, protect the patient and call for assistance.


Hypoglycaemia (abnormally low glucose levels) can cause neurological deterioration, as the brain relies on blood glucose for energy (Harvard Medical School 2019). It may be caused by:

  • Fasting;
  • Poor nutrition;
  • Administration of insulin;
  • Medications;
  • Excessive alcohol consumption; and
  • Endocrine disorders.

Other causes of neurological deterioration include:

  • Traumatic brain injury;
  • Tumours;
  • Lack of oxygen (e.g. from drowning or a heart attack)
  • Infections;
  • Toxins (e.g. carbon monoxide); and
  • Drugs and alcohol.

(Mayo Clinic 2018)


Managing Neurological Deterioration
  • Assess the patient using the GCS in conjunction with a head-to-toe assessment.
  • Assess the patient’s level of consciousness.
  • Ensure the patient is free from any environmental danger. If the patient is on the floor, call for assistance and only move them to the bed if they are haemodynamically stable and all manual handling equipment is available.
  • Support the patient’s respiratory demands.
  • Increase the frequency of observations.
  • Coordinate relevant scans and tests.
  • Implement 3 or 5-lead cardiac monitoring if appropriate.
  • Optimise oxygenation and perfusion status.
  • Perform basic life support if required.
  • Care may need to be escalated to critical care services.



  • The patient may be unable to protect their own airway - this is an emergency situation.
  • If the patient is unresponsive, commence basic life support.
  • If a post-collapse injury occurs, escalate care as required.
  • Consider critical care admission if required.

Early detection of neurological deterioration contributes to successful intervention and favourable patient outcomes. Ensure you:

  • Treat the patient’s signs and symptoms promptly;
  • Increase the frequency of observation;
  • Identify the cause of the deterioration;
  • Correct any metabolic and electrolyte imbalances; and
  • Support the patient’s haemodynamic status.

Note: This article is intended as a refresher and should not replace best-practice care. Always refer to your facility's policy on recognising and responding to acute neurological deterioration.

Additional Resources
  • Critical Care Services Ontario, Guidelines for Basic Adult Neurological Observation
  • Glasgow Coma Scale
  • Neurological Assessment and GCS
Multiple Choice Questions Q1. How is neurological deterioration defined using the GCS?
  • An increase of two points.
  • A decrease of two points.
  • A score of below eight points.
  • A score of above eight points.
  • Q2. True or false? Hypoglycaemia refers to abnormally high blood glucose levels.
  • True
  • False
  • Q3. Which of the following can cause neurological deterioration?
  • Ischaemic stroke.
  • OHaemorrhagic stroke.
  • Space-occupying lesion.
  • All of the above.

    • Brutsaert, E F 2019, ‘Hypoglycemia’, MSD Manual, viewed 14 May 2020, https://www.msdmanuals.com/home/hormonal-and-metabolic-disorders/diabetes-mellitu s-dm-and-disorders-of-blood-sugar-metabolism/hypoglycemia?query=Hypoglycemi a#v773444
    • Clinical Excellence Commission 2013, Patient Controlled Analgesia, Clinical Excellence Commission, viewed 14 May 2020, http://cec.health.nsw.gov.au/__data/assets/pdf_file/0009/259209/patient-safety-report-pc a-web.pdf
    • Cooksley, T, Rose, S & Holland, M 2018, ‘A Systematic Approach to the Unconscious Patient’, Clin Med (Lond), vol. 18 no. 1, viewed 14 May 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6330912/
    • Critical Care Services Ontario 2015, Guidelines for Basic Adult Neurological Observation, Critical Care Services Ontario, viewed 14 May 2020, https://www.criticalcareontario.ca/EN/Education/CCSO%20Webinar-Adult%20BNO%20Guideli nes-Nov%2012%202015.pdf
    • Harvard Medical School 2019, Hypoglycemia, Harvard Health Publishing, viewed 14 May 2020, https://www.health.harvard.edu/a_to_z/hypoglycemia-a-to-z
    • Jeffery, R C H, Young, B, Swann, P G & Lueck, C J 2019, Unequal Pupils, Royal Australian College of General Practitioners, viewed 14 May 2020, https://www1.racgp.org.au/getattachment/26f85d1e-c084-4ae7-ac27-58839cd3d0b1/Unequal-pupils.aspx
    • Kutlu, N O, Emeksiz, S, Alkan, G, Alacakir, N & Caksen, H 2014, ‘Abstract 843: Seizure as a Cause of Unilateral Mydriasis in Critical Patients’, Pediatric Critical Care Medicine, vol. 15 no. 4, viewed 14 May 2020, https://journals.lww.com/pccmjournal/Fulltext/2014/05001/ABSTRACT_843__SEIZURE_AS_A_CAUSE_OF_UNILATE RAL.840.aspx
    • Mayo Clinic 2018, Coma, Mayo Clinic, viewed 14 May 2020, https://www.mayoclinic.org/diseases-conditions/coma/symptoms-causes/syc-20371099
    • Schiller, E Y, Goyal, A, Cao, F & Mechanic, O J 2020, ‘Opioid Overdose’, StatPearls, viewed 14 May 2020, https://www.ncbi.nlm.nih.gov/books/NBK470415/
    • Shkirkova, K, Saver, J L, Starkman, S et al. 2018, ‘Frequency, Predictors, and Outcomes of Prehospital and Early Postarrival Neurological Deterioration in Acute Stroke’, JAMA Neurology, viewed 14 May 2020, https://jamanetwork.com/journals/jamaneurology/fullarticle/2688300
    • Stroke Foundation 2017, Clinical Guidelines for Stroke Management, Stroke Foundation, viewed 14 May 2020, https://informme.org.au/Guidelines/Clinical-Guidelines-for-Stroke-Management-2017
    • Vincent, J et al. 2018, ‘Improving Detection of Patient Deterioration in the General Hospital Ward Environment’, Eur J Anaesthesiol, vol. 35 no. 5, viewed 14 May 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5902137/


    (Answers : b, b, d)





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    Causes of Acute Neurological Deterioration
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