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Difficulty: MediumNeurosurgery

Family members bring a 68-year-old male to the emergency room due to a progressive decline in his mental status over the last 72 hours. He has a past medical history of normal pressure hydrocephalus, which was treated with the placement of a ventriculoperitoneal (VP) shunt four years ago. According to his relatives, he has been reporting severe, diffuse headaches and experienced two episodes of non-bilious vomiting this morning. Upon physical examination, the patient appears lethargic but localizes appropriately to painful stimuli. His temperature is 36.9∘C36.9^{\circ} \text{C} (98.4∘F98.4^{\circ} \text{F}), blood pressure is 170/92 mm Hg170/92 \text{ mm Hg}, pulse is 52/min52/\text{min}, and respiratory rate is 12/min12/\text{min} and irregular. Funduscopic evaluation demonstrates bilateral blurring of the optic disc margins with absent venous pulsations. Which of the following is the most appropriate next step in the management of this patient?

  1. Noncontrast CT scan of the headAnswer
  2. B
    Lumbar puncture
  3. C
    Intravenous ceftriaxone and vancomycin
  4. D
    Intravenous dexamethasone
  5. E
    Exploratory laparotomy

Answer

The most appropriate next step is a noncontrast CT scan of the head to evaluate for ventricular dilation indicative of shunt malfunction.
The correct answer is a noncontrast CT scan of the head. This patient's progressive lethargy, headaches, vomiting, and objective physical findings (bradycardia, hypertension, irregular respirations, papilledema) form a classic picture of acutely elevated intracranial pressure (ICP). Given his history of a ventriculoperitoneal (VP) shunt, the most likely etiology is mechanical shunt malfunction leading to hydrocephalus. A noncontrast CT of the head is the fastest and most reliable initial test to confirm ventricular enlargement compared to previous baseline imaging, guiding the need for emergent neurosurgical shunt revision.

Step-by-Step Solution

1
Analyze the clinical signs and vital signs.
The patient exhibits a classic Cushing reflex (hypertension, bradycardia, irregular respirations) along with papilledema and vomiting.
These findings are hallmark indicators of acutely elevated intracranial pressure (ICP).
2
Integrate the patient's medical history.
The patient has a ventriculoperitoneal (VP) shunt, making a mechanical obstruction or failure the most likely cause of his elevated ICP.
Shunt failure leads to the re-accumulation of cerebrospinal fluid and obstructive hydrocephalus.
3
Determine the safest and most effective diagnostic modality.
A noncontrast CT scan of the head is selected as the initial diagnostic step.
It rapidly visualizes ventricular size to confirm the diagnosis of hydrocephalus while avoiding the herniation risks associated with a lumbar puncture.

Key Concept

Patients with a ventriculoperitoneal (VP) shunt who present with signs of elevated intracranial pressure (headache, vomiting, lethargy, papilledema, Cushing reflex) require immediate neuroimaging, typically a noncontrast CT scan of the head, to evaluate for shunt malfunction and hydrocephalus.

Alternative Method

In some specialized centers, a 'shunt series' (rapid plain radiographs of the skull, neck, chest, and abdomen) is obtained simultaneously with the head CT to trace the mechanical integrity of the entire shunt tubing for disconnections or kinks.
Estimated Time:1m 0s
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Neurosurgery

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