From the Guidelines
Fixed dilated pupils in cerebral stroke are a sign of severe brain injury and increased intracranial pressure, indicating a high risk of deterioration and poor outcome.
Significance of Fixed Dilated Pupils
- Fixed dilated pupils can be a sign of third nerve palsy due to transtentorial herniation, which is a life-threatening complication of increased intracranial pressure 1
- The development of midposition pupils and worsening of motor response may also indicate deterioration in patients with supratentorial ischemic stroke 1
- Clinicians should frequently monitor level of arousal and ipsilateral pupillary dilation in patients with supratentorial ischemic stroke at high risk for deterioration 1
- Changes in pupillary size, including dilation, can be a sign of brainstem compression and increased intracranial pressure in patients with cerebellar infarction 1
Management and Monitoring
- Patients with suspected elevation in intracranial pressure may be managed according to institutional protocols, such as administration of hyperosmolar therapy and head of bed elevation 1
- Close and frequent monitoring of neurological status, including assessments of level of consciousness, worsening symptom severity, and blood pressure, is crucial in patients at high risk for deterioration 1
- Repeat CT scans are recommended for patients when deterioration in neurological status occurs, including changes in pupillary size or reactivity 1
From the Research
Significance of Fixed Dilated Pupils in Cerebral Stroke
- Fixed dilated pupils in cerebral stroke patients can be an ominous sign of brainstem dysfunction, indicating a severe prognosis 2.
- Bilateral fixed dilated pupils can be present in basilar artery occlusion (BAO), which has a high mortality rate of over 85% 2.
- However, with timely and adequate treatment, such as recanalization, a good outcome can be obtained in up to 35% of patients, and mortality can be reduced to 40% 2.
- Unilateral fixed dilation of the pupil can be a false-localizing sign in patients with intracranial hemorrhage, and its presence does not always indicate a bad outcome 3.
- Pupillary dilation can be associated with decreased brain stem blood flow (BBF), and ischemia, rather than mechanical compression of the IIIrd cranial nerve, may be an important causal factor 4.
- Objective pupillometry can be used to evaluate the pupillary light reflex and correlate with midline shift in acute stroke patients, providing valuable information for diagnosis and treatment 5.
- Fixed dilated pupils after cardiac surgery can rarely be caused by bilateral anteromedial midbrain infarctions, which can be differentiated from diffuse hypoxic-ischemic injury 6.
Prognosis and Treatment
- The presence of fixed dilated pupils in cerebral stroke patients should not be accepted as a sign of a definite bad outcome, and all efforts should be focused on finding the right diagnosis in a timely manner 2.
- Timely recanalization within 12 hours and potentially up to 24 hours is the goal for treating BAO patients, which can lead to a favorable outcome 2.
- Pupillary dysfunction can be an indicator of ischemia of the brain stem, and rapid restoration of cerebral blood flow and cerebral perfusion pressure may improve the prognosis 4.