In a patient with a sudden onset exertional headache during heavy lifting, facial and neck rash, neck discomfort, and a normal neurological examination, is emergent non‑contrast head CT still indicated?

Yes, Emergent Non-Contrast Head CT Is Absolutely Indicated Despite Normal Neurological Examination

This patient meets multiple high-risk Ottawa SAH Rule criteria (exertional onset + neck discomfort) and therefore requires immediate non-contrast head CT regardless of a normal neurological examination. 1

Why Imaging Cannot Be Deferred Based on Normal Exam Alone

Ottawa SAH Rule Application

Your patient triggers at least two of the six Ottawa SAH Rule criteria, which mandates further investigation: 1

• Onset during exertion (heavy lifting) – explicitly listed criterion
• Neck pain or stiffness (neck discomfort) – explicitly listed criterion

The Ottawa SAH Rule was prospectively validated in 1,153 patients and demonstrated 100% sensitivity for detecting subarachnoid hemorrhage, meaning a normal neurological exam does not exclude SAH when clinical red flags are present. 1, 2

The Critical Distinction: Chronic vs. Acute Presentation

The evidence showing imaging is unnecessary in neurologically intact patients applies only to chronic headache (≥15 days/month for >3 months), where the yield is 0.2–0.5%. 3 Your patient has a sudden-onset exertional headache—an entirely different clinical scenario with SAH prevalence of approximately 2.7% in neurologically intact patients presenting to emergency settings. 4

Optimal Imaging Strategy

Timing-Dependent Approach

If presenting within 6 hours of symptom onset: 1

• Non-contrast head CT performed within 6 hours has 98.7% sensitivity for SAH (missing <1.5 in 1,000 cases) when interpreted by a neuroradiologist or radiologist experienced in brain imaging. 1, 5
• If CT is negative and read by an experienced neuroradiologist, no lumbar puncture is required. 1

If presenting >6 hours from symptom onset: 1, 5

• CT sensitivity drops considerably (≤90% beyond 6 hours). 5
• Lumbar puncture with spectrophotometric analysis for xanthochromia is mandatory following negative CT when clinical suspicion remains high. 1
• Xanthochromia evaluation is most sensitive after 12 hours from headache onset, though this delay may not always be clinically appropriate. 1

Technical Requirements for CT Adequacy

The high sensitivity cited applies only when: 1

• High-quality (third-generation or higher) CT scanner is used
• Images are interpreted by a fellowship-trained, board-certified neuroradiologist or radiologist who routinely interprets brain imaging
• If these conditions are not met, lumbar puncture should be performed even with negative CT. 1

Why the Normal Neurological Exam Is Misleading Here

Atypical Presentations Still Require Full Workup

The 2023 AHA/ASA guidelines explicitly state: "It is important to note that many of these analyses do not apply to patients with atypical presentations such as primary neck pain... Therefore, the lack of a classic presentation should still prompt appropriate imaging and workup." 1

Your patient's presentation includes:

• Neck discomfort as a prominent feature
• Facial and neck rash (potentially representing sympathetic dysfunction or vascular phenomenon)
• Exertional trigger

The Stakes of Missing SAH

• Case fatality is approximately 50% overall (including pre-hospital deaths). 6
• One-third of survivors remain dependent. 6
• Misdiagnosis is most likely in patients with normal neurological examination, and the consequences are catastrophic. 4, 7
• Diagnosis of a sentinel bleed before catastrophic rupture is lifesaving. 1

Common Pitfalls to Avoid

Do not apply chronic headache imaging guidelines to acute presentations. The evidence showing low yield (0.2%) applies only to patients with chronic headache (≥3 months duration) and normal exams—not sudden-onset exertional headaches. 3

Do not assume a normal neurological exam excludes SAH. The Ottawa SAH Rule exists precisely because neurologically intact patients can harbor life-threatening hemorrhage. 1, 2

Do not skip lumbar puncture if CT is performed >6 hours from onset or lacks expert interpretation. The CT-LP pathway has 100% sensitivity when properly executed. 5

Do not order CTA as a substitute for CT followed by LP. CTA evaluates only cerebrovascular pathology (sensitivity ~97.2% for aneurysms, but only 61% for aneurysms <3 mm) and does not directly detect subarachnoid blood. 1