What is the management of anisochoric pupil (unequal pupil size) after head trauma?

Management of Anisochoric Pupil After Head Trauma

Anisocoria (unequal pupil size) after head trauma requires urgent neuroimaging and may indicate the need for intracranial pressure monitoring, especially when accompanied by other neurological deficits. 1

Initial Assessment

• Immediate non-contrast CT scan is essential to characterize potential intracranial hematomas, midline shift, or other traumatic brain injuries 2
• Complete neurological assessment using Glasgow Coma Scale (GCS), detailed pupillary examination (size, reactivity, and symmetry), and evaluation of focal neurological deficits 2
• Check for anticoagulant or antiplatelet medication use, as these increase risk of hematoma expansion 2
• Secure airway with tracheal intubation if GCS ≤8 or if there are signs of increased intracranial pressure 2

Significance of Anisocoria

• Anisocoria after head trauma is a significant clinical finding that may indicate expanding intracranial mass lesion 3
• Preoperative anisocoria is considered a criterion for intracranial pressure (ICP) monitoring after evacuation of post-traumatic intracranial hematoma 1, 4
• Pupillary status is a strong prognostic factor - bilateral fixed dilated pupils have the highest mortality rate (79.7%), while unilateral fixed dilated pupils have a mortality rate of approximately 27.6% 5, 6

Management Algorithm

For patients with anisocoria and abnormal CT findings:

1. If CT shows significant midline shift (>5mm) or hematoma:

   • Urgent neurosurgical consultation for potential surgical evacuation 7
   • Consider decompressive craniectomy, especially in younger patients with refractory intracranial hypertension 2, 7

2. After hematoma evacuation:

   • ICP monitoring is strongly indicated if anisocoria was present preoperatively 1, 4
   • Maintain cerebral perfusion pressure between 60-70 mmHg 1, 4
   • Avoid cerebral perfusion pressure >70 mmHg as it increases risk of respiratory distress syndrome 1

For patients with anisocoria but normal initial CT:

• Close neurological monitoring with serial pupillary examinations 2
• Consider repeat CT if neurological status deteriorates 1
• ICP monitoring may still be indicated if neurological surveillance is not feasible or if patient has hemodynamic instability 1, 4

Special Considerations

• Rule out artificial eye as a cause of anisocoria in unconscious patients (check corneal reflex and manual palpation of the bulbus) 3
• Traumatic optic neuropathy may occur with head trauma and requires case-by-case management 8
• Long-term ophthalmological deficits are common (72%) in survivors with fixed dilated pupils 9
• Age, initial ICP, and pupil status are significant predictive factors of outcome 5

Pitfalls to Avoid

• Delaying neuroimaging in patients with anisocoria after head trauma 2
• Assuming poor prognosis based solely on pupillary findings - even patients with bilateral fixed dilated pupils can achieve good functional outcomes in some cases (1.4%) 5, 6
• Overlooking the need for ICP monitoring after hematoma evacuation in patients with preoperative anisocoria 1, 4
• Failing to maintain appropriate cerebral perfusion pressure (60-70 mmHg) in patients with traumatic brain injury 1