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Difficulty: EasyNeurosurgery

A 38-year-old woman is evaluated in the emergency department due to the sudden onset of a severe headache that began 4 hours ago. She describes it as the "worst headache I have ever had in my entire life." She has no significant past medical history and takes no medications. Vital signs are temperature 37.0°C (98.6°F), blood pressure 150/90 mmHg, heart rate 92/min, and respiratory rate 16/min. On physical examination, she is awake, alert, and oriented (Glasgow Coma Scale score 15). Cranial nerve function is intact, and there are no focal sensory or motor deficits in the extremities. She exhibits marked photophobia and nuchal rigidity. A computed tomography scan of the head without contrast reveals no intracranial abnormalities. Which of the following is the most appropriate next step in management?

  1. A
    Magnetic resonance imaging of the brain
  2. B
    Empiric administration of ceftriaxone and vancomycin
  3. Lumbar punctureAnswer
  4. D
    Catheter-based cerebral angiography
  5. E
    Administration of sumatriptan and discharge

Answer

Lumbar puncture
The correct answer is lumbar puncture. This patient has the classic presentation of a subarachnoid hemorrhage (SAH), marked by a sudden, extremely severe "thunderclap" headache and signs of meningeal irritation (nuchal rigidity, photophobia). The first step in evaluating suspected SAH is a non-contrast CT of the head. However, if the CT is negative and clinical suspicion remains high (which is common, as CT sensitivity is not 100% and decreases over time), the next required step is a lumbar puncture. The cerebrospinal fluid is examined for elevated red blood cells and xanthochromia (a yellowish discoloration caused by the breakdown of hemoglobin), which confirms the diagnosis.

Step-by-Step Solution

1
Analyze the patient's symptoms and examination findings.
The patient presents with a sudden-onset "thunderclap" headache, photophobia, and nuchal rigidity.
These findings are classic for an acute subarachnoid hemorrhage (SAH), prompting immediate diagnostic evaluation.
2
Evaluate the results of the initial diagnostic workup.
The initial non-contrast head CT is negative for hemorrhage.
Non-contrast CT is highly sensitive for acute SAH, but its sensitivity decreases as time passes from the initial bleeding event, meaning a negative CT does not definitively rule out the condition.
3
Determine the necessary subsequent diagnostic intervention.
A lumbar puncture must be performed to check the cerebrospinal fluid for red blood cells and xanthochromia (bilirubin).
When clinical suspicion for SAH remains high despite a negative head CT, a lumbar puncture is the mandatory next step to confirm or exclude the diagnosis.

Key Concept

In patients with a high clinical suspicion for subarachnoid hemorrhage (SAH) who have a negative non-contrast head CT, a lumbar puncture is required to definitively diagnose or rule out the condition.
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Topics

Neurosurgery

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