What is the management approach for a patient presenting with a left-sided dilated pupil and altered sensorium (changed mental status)?

Management of Left-Sided Dilated Pupil with Altered Sensorium

This presentation represents a neurological emergency requiring immediate neuroimaging and urgent neurosurgical evaluation, as ipsilateral pupillary dilation with altered mental status most commonly indicates uncal herniation from a supratentorial mass lesion causing brainstem compression. 1

Immediate Assessment and Stabilization

Perform rapid neurological examination focusing on:

• Glasgow Coma Scale score to quantify level of consciousness 1
• Pupillary size, reactivity, and symmetry - document if the dilated pupil is fixed or sluggishly reactive 1
• Motor responses and presence of extensor posturing 1
• Respiratory pattern abnormalities (central neurogenic hyperventilation, ataxic breathing) 1
• Contralateral motor weakness or Babinski sign 1

Critical diagnostic consideration: While ipsilateral pupillary dilation typically indicates herniation on the same side as the mass, be aware that contralateral (false-localizing) pupillary dilation can occur in 10-15% of cases with hemispheric lesions. 2

Emergency Neuroimaging

Obtain immediate head CT without contrast to identify:

• Supratentorial hemorrhage (intracerebral, subdural, epidural) 1, 3
• Cerebral infarction with edema and mass effect 1
• Midline shift and subfalcine herniation 3
• Cerebellar infarction with brainstem compression 1
• Basilar artery occlusion if posterior circulation stroke suspected 4

If CT shows vascular occlusion or aneurysm is suspected, proceed immediately with CT angiography or MR angiography. 1, 4

Immediate Medical Management

Initiate osmotic therapy immediately while arranging definitive intervention:

• Mannitol 1 g/kg of 20% solution OR hypertonic saline 0.686 mL/kg of 23.4% (equiosmolar doses) 1
• Elevate head of bed to 30 degrees 1
• Maintain adequate cerebral perfusion pressure, as decreased brainstem blood flow below 40 mL/100 g/min correlates with pupillary dilation and poor outcome 5

Do NOT use corticosteroids, hypothermia, or barbiturates - insufficient evidence of benefit and not recommended for ischemic cerebral swelling. 1

Urgent Neurosurgical Consultation

Contact neurosurgery immediately for consideration of:

• Decompressive hemicraniectomy for malignant hemispheric infarction with herniation 1, 3
• Hematoma evacuation for traumatic or spontaneous intracranial hemorrhage 3
• External ventricular drain placement if hydrocephalus present 1
• Suboccipital decompression for cerebellar infarction with brainstem compression 1

Specific Etiologies to Consider

Ischemic stroke with herniation:

• Progressive rostrocaudal deterioration with ipsilateral pupillary dysfunction and mydriasis 1
• Basilar artery occlusion can cause bilateral dilated pupils from mesencephalic ischemia - consider endovascular thrombectomy within 12-24 hours even with bilateral fixed pupils, as favorable outcomes occur in up to 35% with recanalization 4

Hemorrhagic stroke:

• Intracerebral hemorrhage with peri-hematoma edema causing mass effect 3
• Subarachnoid hemorrhage from aneurysm rupture (especially posterior communicating artery) 1

Cerebellar pathology:

• Monitor for pinpoint pupils, anisocoria, loss of oculocephalic responses, bradycardia, and irregular breathing patterns indicating brainstem compression 1

Critical Pitfalls to Avoid

Do not assume bilateral fixed dilated pupils indicate futility - with basilar artery occlusion, timely recanalization can produce favorable outcomes despite this ominous sign. 4

Do not rely solely on pupillary lateralization - false-localizing pupillary signs occur, and disparate herniation mechanisms can arise from the same hemispheric lesion. 2

Do not delay intervention for complete diagnostic workup - pupillary dilation with altered sensorium represents impending herniation requiring immediate osmotic therapy and surgical evaluation. 1, 3

Recognize that decreased brainstem blood flow, not just mechanical compression, causes pupillary dilation - rapid restoration of cerebral perfusion pressure may reverse pupillary changes and improve prognosis. 5

Monitoring During Resuscitation

Continuously assess:

• Pupillary size and reactivity every 15-30 minutes 1
• Glasgow Coma Scale score 1
• Motor responses and development of posturing 1
• Respiratory pattern changes 1
• Intracranial pressure if monitor placed 5

Document timing of pupillary changes as rapid reversal after surgical decompression indicates successful intervention. 3