A simplified approach to spontaneous eye movements in coma is:
- roving eye movements — metabolic/ toxic encephalopathy most likely, or although they can also occur with bilateral lesions above the brainstem.
- other ‘weird and wonderful’ eye movements — structural, metabolic or toxicological cause of comas.
- saccadic eye movements or fixing and following — pseudocoma (feigned coma).
Most individuals have a degree of exophoria when drowsy for any reason and any underlying strabismus tends to worsen — thus dysconjugate gaze is difficult to interpret in the stuporous or comatose patient.
TYPES OF EYE MOVEMENTS
Eye movements seen in the comatose patient include:
- roving eye movements —
Description: slow random predominantly horizontal conjugate eye movements (though there may be a degree of exophoria) similar to those seen in deep sleep.
Likely cause: metabolic encephalopathy (may be absent in deep coma), bilateral supranuclear lesions
- ocular bobbing —
Description: Rapid, conjugate, downward movement; slow return to primary position
Likely cause: Pontine strokes; other structural, metabolic, or toxic disorders
- ocular dipping —
Description: Slow downward movement; rapid return to primary position
Likely cause: Unreliable for localization; follows hypoxic-ischemic insult or metabolic disorder
- reverse ocular bobbing —
Description: Rapid upward movement; slow return to primary position
Likely cause: Unreliable for localization; may occur with metabolic disorders
- reverse ocular dipping —
Description: Slow upward movement; rapid return to primary position
Likely cause: Unreliable for localization; pontine infarction and with AIDS
- ping-pong gaze —
Description: Horizontal conjugate deviation of the eyes, alternating every few seconds
Likely cause: metabolic encephalopathy, bilateral cerebral hemispheric dysfunction; toxic ingestion
- periodic alternating gaze deviation —
Description: Horizontal conjugate deviation of the eyes, alternating every 2 minutes
Likely cause: Hepatic encephalopathy; disorders causing periodic alternating nystagmus and unconsciousness or vegetative state
- vertical myoclonus —
Description: vertical pendular oscillations (2–3 Hz)
Likely cause: Pontine strokes
- horizontal myoclonus —
Description: rapid horizontal pendular oscillations; the eyes appear to be shaking.
Likely cause: Serotonin toxicity
- monocular eye movements —
Description: Small, intermittent, rapid monocular horizontal, vertical, or torsional movements
Likely cause: Pontine or midbrain destructive lesions, perhaps with coexistent seizures
References and Links
- Posner JB, Saper CB, Schiff N, Plum F. Plum and Posner’s Diagnosis of Stupor and Coma 4e Oxford university Press, 2009.
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.