From the Guidelines
A computed tomography (CT) head scan without contrast is indicated for patients with headache and neck pain who meet specific criteria, such as those outlined in the Ottawa SAH Rule, which includes patients with new severe nontraumatic headache reaching maximum intensity within 1 hour, age ≥40 years, neck pain or stiffness, witnessed loss of consciousness, onset during exertion, thunderclap headache, or limited neck flexion on examination 1.
When evaluating patients with headache and neck pain, it is essential to consider the potential for serious underlying conditions, such as subarachnoid hemorrhage (SAH). The Ottawa SAH Rule provides a framework for identifying patients who require additional investigation for SAH, including a noncontrast head CT scan. According to the 2023 guideline for the management of patients with aneurysmal subarachnoid hemorrhage, a high-quality CT scanner can detect SAH with a high sensitivity, especially when the images are interpreted by fellowship-trained, board-certified neuroradiologists 1.
Key points to consider when deciding whether to order a CT head scan without contrast include:
- Patient age ≥40 years
- Presence of neck pain or stiffness
- Witnessed loss of consciousness
- Onset of headache during exertion
- Thunderclap headache (instantly peaking pain)
- Limited neck flexion on examination
- Patients who present within 6 hours of headache onset with no new neurological deficits, a noncontrast head CT is likely sufficient to exclude SAH 1
It is crucial to note that many analyses do not apply to patients with atypical presentations, such as primary neck pain, syncope, seizure, or new focal neurological deficit. In these cases, the lack of a classic presentation should still prompt appropriate imaging and workup 1.
The use of the Ottawa SAH Rule can help identify a subset of patients who are unlikely to have SAH, thereby avoiding additional imaging and workup that use resources and expose patients to unnecessary risk 1.
From the Research
Indications for CT Head Scan without Contrast
- A CT head scan without contrast is typically used as the first imaging technique after head injury, as stated in the study by 2.
- It is useful for demonstrating scalp, bone, extra-axial hematomas, and parenchymal injury, and can be used to evaluate the bony anatomy of the spine, as noted in the study by 2.
- For patients presenting with acute non-traumatic headache, the Ottawa subarachnoid haemorrhage rule can be used to aid in the decision for CT of the head, as shown in the study by 3.
CT Head Scan without Contrast for Headache and Neck Pain
- There is limited direct evidence on the use of CT head scans without contrast specifically for headache and neck pain.
- However, the study by 4 highlights the importance of noncontrast head CT in detecting subtle vascular changes, which can be life-saving in some cases.
- The study by 5 found that CT angiography can be useful in patients with acute severe headache, but it is not clear if this applies to patients with headache and neck pain.
Diagnostic Yield and Complications
- The study by 6 found that lumbar puncture after a negative head CT had a low diagnostic yield for subarachnoid hemorrhage, but was associated with complications and extended length of stay.
- The study by 5 found a high percentage of vascular abnormalities in patients with acute severe headache who underwent CT angiography, but it is not clear if this applies to patients with headache and neck pain.