Reviewed and revised 20 September 2016
- Pseudocoma is the term used for a patient feigning a comatose state, however it is sometimes also used for conditions like locked-in syndrome where patients may involuntarily appear unconscious but are actually self aware
- This document focusses on how to distinguish feigned coma from true coma
The pattern of clinical findings are not consistent with a specific neurological syndrome or anatomical lesion.
- pupils are equal and reactive to light.
- passive eyelid opening results in pupillary constriction, whereas if the patient is sleeping or comatose (with intact pupillary reflexes) the pupils dilate on passive eyelid opening.
- Eye movements and oculovestibular reflexes:
- fluttering of the eyelids when the eyelashes are gently stroked
- the patient may resist passive eye opening. Occasionally patients with metabolic or structural lesions may resist eye opening.
- any spontaneous eye movements are saccadic (rapid and jerking) rather than slowly roving
- the patient actually makes eye contact with the examiner when the eyelids are opened; or the eyes always look to the side away from the examiner, or the eyes always look towards the ground
- the awake patient’s eyes move concomitantly with head rotation when assessing the oculocephalic reflex. It is nearly impossible for an awake patient to mimic the brainstem oculocephalic responses of a truly comatose patient.
- on cold caloric testing the patient may wake up or exhibit preservation of the fast component of nystagmus.
- active resistance or varying resistance to passive motor tone testing, or cog-wheeling resistance with sudden “giving-away” phenomena
- no abnormal reflex posturing in response to painful stimuli
- the patient may occasionally make voluntary movements or change body position in bed
- the patient will show avoidance of ‘self injury’ — do not allow the patient to be injured!
- Eyelid apraxia (or lid opening apraxia) is the inability to voluntarily open eyes despite intact frontalis muscle contraction and normal oculomotor function
- Is an unusual coma mimic
- Caused by injuries of:
- the nondominant hemisphere (e.g. R MCA stroke)
- medial frontal lobe
- bilateral thalami (e.g. bilateral thalamic stroke)
- brainstem (e.g. progressive supranuclear palsy)
- Suspect this condition if the patient tries to raise their eyelids by contracting forehead muscles when asked to open eyes
References and Links
- Poser JB, et al. Plum and Posner’s Diagnosis of Stupor and Coma (4th edition), Oxford university Press, 2007.