🩺What is Stroke (Cerebrovascular Accident)?
The FOUR Score evaluates four domains: Eye response (0-4), Motor response (0-4), Brainstem reflexes (0-4), and Respiration (0-4). Total score ranges from 0-16. It provides more neurological detail than GCS, including brainstem function and respiratory patterns, making it particularly useful in the ICU setting.
📊Clinical Assessment & Risk Scoring
Healthcare professionals use these validated clinical calculators, diagnostic scales, and risk scoring systems to assess the severity, prognosis, or therapeutic dosing requirements for Stroke (Cerebrovascular Accident):
FOUR Score — Full Outline of UnResponsiveness
The FOUR (Full Outline of UnResponsiveness) Score is a coma scale developed as an alternative to the Glasgow Coma Scale (GCS), with advantages in intubated patients and those with severe brain injury.
🧬Diagnostic Logic & Scoring Breakdown
The FOUR Score is calculated by summing the scores of its four components, each scored 0-4. Eye response assesses whether eyes open spontaneously and track the examiner's finger (4), open but do not track (3), open to loud voice (2), open to pain (1), or remain closed with no response (0). Motor response evaluates upper limb function: the patient can make a thumbs-up or fist (4), localizes to pain (3), flexion response to pain (2), extension response to pain (1), or no response (0). Brainstem reflexes assess pupillary light reflex and corneal reflex: both pupil and corneal reflexes present (4), one pupil wide and fixed with corneal reflex present (3), one pupil or one corneal reflex present (2), one of the two reflexes present (1), or both absent (0). Respiration evaluates breathing pattern: regular breathing (4), Cheyne-Stokes respiration (3), irregular breathing (2), mechanically ventilated with triggered breaths (1), or apnea or ventilator-driven respirations (0). The total score ranges from 0 (deep coma/no brainstem function) to 16 (fully conscious with normal brainstem function and respiration). The FOUR Score avoids the verbal component limitation of GCS in intubated patients and incorporates brainstem function assessment, which is critical for prognostication.
📢Clinical Significance & Implications
The FOUR (Full Outline of UnResponsiveness) Score was developed by Dr. Eelco Wijdicks and colleagues at the Mayo Clinic, first published in Neurology in 2005. It was designed to address several limitations of the Glasgow Coma Scale (GCS). First, the FOUR Score eliminates the verbal component, which cannot be assessed in intubated patients — a significant limitation of GCS in ICU settings where up to 40-60% of patients are intubated. Second, it incorporates brainstem reflex assessment (pupillary light reflex and corneal reflex), providing critical neurological information that GCS omits. Brainstem function is one of the strongest predictors of outcome after severe brain injury. Third, the FOUR Score includes respiratory pattern assessment, capturing important clinical information about brainstem respiratory centers. Fourth, the motor component is tested in the upper limbs only, avoiding the confounding effect of lower extremity spinal cord injury. The FOUR Score has been validated across multiple clinical settings including traumatic brain injury, intracerebral hemorrhage, subarachnoid hemorrhage, cardiac arrest, and general neurocritical care populations. Studies have demonstrated excellent inter-rater reliability, with weighted kappa values exceeding 0.80 across all four components. The FOUR Score has also shown comparable or superior prognostic accuracy to GCS for predicting mortality and poor functional outcomes after severe brain injury. A score of 0 on the FOUR Score (all four components absent) is a critical finding that, in the absence of sedative medications, raises concern for brain death and should prompt formal brain death evaluation. Major neurocritical care societies, including the Neurocritical Care Society (NCS), recognize the FOUR Score as a valuable complement to GCS in the ICU setting.
💡 Clinical Assessment Scenario Example
A 55-year-old male is admitted to the ICU following a massive intracerebral hemorrhage. On neurological examination, his eyes are closed and do not open to verbal stimulation but open briefly to painful nail bed pressure — he does not track the examiner's finger (Eye = 1). Motor examination shows the patient extends his arms to painful stimulation (decerebrate posturing) — no localization or withdrawal (Motor = 1). Pupillary examination reveals both pupils are 4 mm and sluggishly reactive to light; the corneal reflex is absent bilaterally — only one reflex (pupillary) is partially present (Brainstem = 1). The patient is on mechanical ventilation with no spontaneous respiratory efforts above the set rate (Respiration = 0). Total FOUR Score = 1 + 1 + 1 + 0 = 3/16. This indicates severe brain injury with extremely high mortality risk. The patient requires neuroprotective measures including head-of-bed elevation, avoidance of hyperthermia and hyperglycemia, and ICP monitoring. Given the brainstem involvement and poor neurological exam, discussions regarding goals of care and prognosis should be initiated with the family.
💊Common Medications & Interventions
The following pharmacological therapies and substances are commonly referenced or adjusted based on the clinical assessment of Stroke (Cerebrovascular Accident):
⚠️Clinical Assessment Pitfalls
❌ Mistake: Confusing FOUR Score motor component with GCS motor scale
✅ Correction: FOUR Score motor response is assessed in the upper limbs only (0-4), while GCS motor is assessed in the best limb (1-6). FOUR tests specific hand commands (thumbs up/fist) rather than general command-following. Do not attempt to convert between the two scales.
❌ Mistake: Scoring brainstem reflexes in patients under sedation
✅ Correction: Sedative medications can suppress pupillary and corneal reflexes. Document any sedative use and, when possible, assess brainstem reflexes during sedation holidays or at trough levels. A FOUR Score of 0 on brainstem reflexes may be drug-induced rather than indicating brain death.
🚑When to Seek Medical Attention
This reference supports clinical assessment of Stroke (Cerebrovascular Accident); it does not replace urgent evaluation. Seek prompt in-person medical care if symptoms are severe, rapidly worsening, or life-threatening, or if you are unsure about a diagnosis or treatment plan. Patients should always consult their physician before starting or changing any therapy.
❓Frequently Asked Questions
Q: How is the FOUR Score different from GCS?
The FOUR Score differs from GCS in four key ways: (1) It eliminates the verbal component, making it assessable in intubated patients. (2) It incorporates brainstem reflex testing (pupillary light reflex and corneal reflex), providing critical information about brainstem function that GCS omits. (3) It includes respiratory pattern assessment. (4) Motor response is tested in upper limbs only (0-4 scale) rather than best limb (1-6). The FOUR Score ranges from 0-16 compared to GCS 3-15. Studies suggest the FOUR Score has comparable or superior prognostic accuracy in neurocritical care populations, particularly for predicting mortality.
Q: What does a FOUR Score of 0 indicate?
A FOUR Score of 0 (Eye 0 + Motor 0 + Brainstem 0 + Respiration 0) indicates absent eye opening, no motor response, absent pupillary and corneal reflexes, and apnea or complete ventilator dependence. In the absence of sedative medications, this is highly concerning for brain death. It should prompt formal brain death evaluation including an apnea test as per local protocols. However, sedatives, neuromuscular blockers, and hypothermia can produce a score of 0 temporarily, so these confounders must be excluded before brain death evaluation.
📚Evidence-Based References
Medically Reviewed By
Dr. Mahmoud El-Sayed
MD, MSc | Neurology
Dr. Mahmoud El-Sayed is a consultant neurologist with over 15 years of experience in clinical neurology, neurocritical care, and stroke medicine.