A 58-year-old right-handed woman is evaluated in the neurosurgical intensive care unit for… — USMLE Step 2 CK

A $58$ -year-old right-handed woman is evaluated in the neurosurgical intensive care unit for new-onset neurological deficits. Six days ago, she underwent successful surgical clipping of a ruptured left middle cerebral artery aneurysm. Her postoperative course had been uncomplicated, and she was alert and fully oriented this morning. Over the past hour, the nurse noted that the patient developed right-sided hemiparesis and severe expressive aphasia.

Her temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), heart rate is $82 \text{ /min}$ , blood pressure is $112/74 \text{ mmHg}$ , and respirations are $14 \text{ /min}$ . A stat noncontrast head computed tomography scan shows expected postsurgical changes with no evidence of new hemorrhage, cerebral edema, or hydrocephalus. Continuous electroencephalography reveals no epileptiform activity.

Which of the following is the most appropriate next step in management?

A
Intravenous administration of nimodipine
B
Transfer to the angiography suite for mechanical thrombectomy
Intravenous administration of norepinephrineAnswer
D
Initiation of therapeutic hyperventilation
E
Lumbar puncture for cerebrospinal fluid analysis

Answer

Intravenous administration of norepinephrine

This patient's new-onset focal neurological deficits (expressive aphasia, right-sided hemiparesis) occurring 6 days after a subarachnoid hemorrhage, combined with a negative computed tomography head scan and electroencephalogram, are highly indicative of delayed cerebral ischemia secondary to cerebral vasospasm. Vasospasm typically occurs between days 3 and 10 following the initial hemorrhage. The initial treatment of choice for symptomatic vasospasm is induced hypertension (using vasopressors such as norepinephrine or phenylephrine) to increase the mean arterial pressure and maintain adequate cerebral perfusion through the narrowed vessels. Maintenance of strict euvolemia is also essential.

Step-by-Step Solution

Analyze the patient's presentation and timeline.

The patient has new-onset focal neurological deficits (aphasia, hemiparesis) occurring 6 days after a subarachnoid hemorrhage.

Establishing the precise timeline is critical for identifying specific post-hemorrhage complications.

Evaluate the diagnostic findings to rule out alternative etiologies.

The CT scan shows no new hemorrhage or hydrocephalus, and the EEG rules out subclinical seizures.

This effectively rules out early complications like rebleeding and hydrocephalus, leaving delayed cerebral ischemia as the primary diagnosis.

Determine the appropriate acute management for delayed cerebral ischemia.

Select induced hypertension (e.g., with norepinephrine).

Acute symptomatic vasospasm requires increasing the mean arterial pressure to force adequate blood flow through the spastic cerebral vessels.

Key Concept

Delayed cerebral ischemia (vasospasm) classically occurs 3 to 10 days after a subarachnoid hemorrhage and is acutely managed with induced hypertension to maintain cerebral perfusion.

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