CT Angiogram Head and Neck in Dizziness: When to Order
CT angiography of the head and neck has extremely limited utility in isolated dizziness, with a diagnostic yield of only 3% and should not be routinely ordered. 1
Evidence Against Routine CTA in Isolated Dizziness
The data is clear and consistent across multiple studies:
- CTA demonstrates a sensitivity of only 14%, specificity of 98%, positive predictive value of 40%, and negative predictive value of 92% for detecting causative pathology in isolated dizziness 1
- In large cohorts, CTA changed clinical management in only 1.3% of patients presenting with uncomplicated dizziness 2
- CTA provides no additional diagnostic information beyond non-contrast head CT in the setting of isolated dizziness 1
- Non-contrast CT actually has higher sensitivity (21.4%) and positive predictive value (100%) compared to CTA (14.3% and 40% respectively) for detecting central causes of dizziness 3
Specific Clinical Scenarios Where CTA May Be Appropriate
High Vascular Risk Patients with Acute Vestibular Syndrome
Order CTA head and neck when patients present with acute persistent vertigo (lasting days to weeks) AND have multiple vascular risk factors including: 4
- History of stroke, TIA, or arterial dissection 5
- Coronary artery disease 5, 6
- Diabetes mellitus 5, 6
- Current or long-term smoking 5
- Hypertension 6
- Current anticoagulation or antiplatelet therapy 5
Suspected Vertebrobasilar Insufficiency
CTA is indicated when dizziness occurs with chronic recurrent brainstem neurologic deficits suggesting posterior circulation pathology 7
- Patients with dizziness face nearly twice the risk for vertebrobasilar artery stenosis compared to those without dizziness (13.3% vs 7.6%) 6
- This risk increases to 19.4% in patients with prior stroke history 6
Pulsatile Tinnitus with Dizziness
CTA head and neck is supported as first-line imaging when dizziness accompanies pulsatile tinnitus to evaluate for: 1
- Vascular malformations (dural arteriovenous fistula, AVM) 1
- Arterial dissection 1
- Sigmoid sinus wall abnormalities 1
- Aberrant vascular anatomy 1
Critical Decision Points: What to Order Instead
For Isolated Dizziness Without Red Flags
No imaging is indicated when: 4
- Brief episodic vertigo with typical BPPV features (seconds to minutes, triggered by head movements) 4
- Acute persistent vertigo with normal neurologic exam AND HINTS examination consistent with peripheral vertigo by a trained examiner 4
- Treatment: Perform canalith repositioning procedures (Epley maneuver) with 80-98% success rate 4
When Imaging IS Needed
Order MRI head without contrast (NOT CTA) for: 4
- Acute persistent vertigo with abnormal neurologic examination 4
- HINTS examination suggesting central cause 4
- Focal neurological deficits 4
- Sudden hearing loss 4
- Inability to stand or walk 4
- New severe headache 4
- Downbeating nystagmus 4
Clinical Decision Rule to Exclude Need for CTA
A validated decision rule can exclude acute vascular pathology with 100% sensitivity and negative predictive value, potentially avoiding CTA in 52% of cases when ALL of the following are absent: 5
- No history of stroke, TIA, or arterial dissection 5
- No coronary artery disease 5
- No diabetes 5
- No migraines 5
- Not a current or long-term smoker 5
- Not on anticoagulation or antiplatelet therapy 5
Common Pitfalls to Avoid
- Do not assume normal neurologic exam excludes stroke: 75-80% of patients with acute vestibular syndrome from posterior circulation infarct have no focal neurologic deficits 4
- Do not order CTA when CT is already negative: CTA adds no diagnostic value beyond non-contrast CT in isolated dizziness 1, 3
- Do not use CT/CTA instead of MRI when stroke is suspected: CT misses many posterior circulation infarcts, which are the most common central cause of acute dizziness 4
- Do not order imaging for typical BPPV: Patients meeting diagnostic criteria with positive Dix-Hallpike test require treatment, not imaging 4