What is the initial evaluation and management of a 13-year-old patient presenting to the Emergency Room with headache and anisocoria (unequal pupil size)?

Emergency Room Evaluation of a 13-Year-Old with Headache and Anisocoria

Immediate neuroimaging with CT scan is essential for any pediatric patient presenting with headache and anisocoria (unequal pupil size) to rule out life-threatening intracranial pathology. 1

Initial Assessment

Urgent Neurological Evaluation

• Monitor level of consciousness and pupillary changes frequently
• Document:
  • Size of both pupils in millimeters
  • Reactivity to light (direct and consensual)
  • Presence of ptosis
  • Extraocular movements
  • Other focal neurologic signs

Red Flags Requiring Immediate Attention

• Sudden onset severe headache
• Altered mental status
• Focal neurological deficits
• Worsening pupillary dilation
• Nausea/vomiting
• Fever
• History of recent trauma

Diagnostic Workup

Immediate Imaging

• Non-contrast CT scan of the head should be performed immediately 1
• If CT is normal but clinical suspicion remains high:
  • Consider CT angiography to evaluate for vascular abnormalities 1
  • Consider MRI if available for better visualization of posterior fossa, brainstem lesions

Laboratory Studies

• Complete blood count
• Basic metabolic panel
• Consider toxicology screen (if altered mental status)
• If fever present: blood cultures, lumbar puncture (only after ruling out increased intracranial pressure)

Differential Diagnosis

Life-Threatening Causes (Require Immediate Intervention)

1. Expanding intracranial mass - tumor, hemorrhage, abscess
2. Increased intracranial pressure - hydrocephalus, cerebral edema
3. Cerebrovascular event - stroke, aneurysm, arterial dissection 2
4. Acute subdural hematoma 3
5. Uncal herniation - progressive anisocoria with ipsilateral pupillary dilation 1

Less Urgent Causes

1. Migraine with pupillary involvement - can cause transient anisocoria 4, 5
2. Pharmacologic mydriasis - accidental exposure to mydriatic agents
3. Physiologic anisocoria - typically <1mm difference, equal reactivity
4. Horner syndrome - ptosis, miosis, anhidrosis
5. Third nerve palsy - pupillary dilation with impaired extraocular movements

Management Algorithm

If Abnormal CT Findings:

1. Immediate neurosurgical consultation 1
2. Elevate head of bed to 30° 1
3. Consider osmotic therapy if evidence of cerebral edema:
   • Mannitol 0.5-1g/kg IV or
   • Hypertonic saline (3%) 1
4. Secure airway if decreased level of consciousness
5. Transfer to tertiary center with neurosurgical capabilities if not available 1

If Normal CT Findings but Persistent Symptoms:

1. Consider additional imaging (MRI, MRA/CTA)
2. Neurological consultation
3. Observe for at least 6 hours with serial neurological examinations
4. Consider lumbar puncture if subarachnoid hemorrhage is suspected and CT is negative 1

If Normal CT and Improving/Resolved Symptoms:

1. Consider migraine as potential diagnosis 4
2. Discharge with close follow-up if:
   • Normal neurological examination
   • Resolution of anisocoria
   • No concerning features
   • Reliable follow-up available 1

Important Caveats

• Do not administer sedatives without securing airway in patients with fluctuating consciousness
• Do not perform lumbar puncture before ruling out increased intracranial pressure
• Do not assume migraine as the cause without first excluding life-threatening conditions
• Do not delay neuroimaging in a patient with new-onset anisocoria and headache
• Anisocoria that develops during a headache episode requires thorough investigation even if other symptoms are consistent with migraine 4

Follow-up Recommendations

• Neurology follow-up within 1-2 weeks if discharged
• Return to ED instructions for worsening symptoms
• Documentation of pupil size and reactivity at discharge as baseline

Remember that anisocoria with headache in a pediatric patient should be considered a neurological emergency until proven otherwise, as early detection and management of intracranial pathology significantly impacts morbidity and mortality outcomes.