Transcranial Doppler: Windows, Velocities, Sickle Cell Disease (STOP), Vasospasm and Reporting
The windows and vessels of transcranial Doppler, reference velocities, the STOP criteria in sickle cell disease, grading vasospasm with the Lindegaard ratio and what to write in the report.
LaudárioUltrasound reports in practice
Transcranial Doppler measures flow velocity in the large intracranial arteries through acoustic windows in the skull, and its two classic indications are stroke risk screening in sickle cell disease and vasospasm surveillance after subarachnoid hemorrhage. The cut-offs in these two settings differ and rely on different parameters, so the report must state which velocity was measured and in which vessel.
Transcranial Doppler: windows, vessels and velocities
Values from a 2026 review, for adults. Depth ranges vary across sources, and velocities fall with age.
| Window | Artery | Depth (mm) | Mean velocity (cm/s) |
|---|---|---|---|
| Temporal | Middle cerebral | 30 to 67 | 62 ± 12 |
| Temporal | Anterior cerebral | 60 to 80 | 50 ± 11 |
| Temporal | Terminal internal carotid | 60 to 67 | 39 ± 9 |
| Temporal | Posterior cerebral | 55 to 80 | 39 ± 10 |
| Orbital | Ophthalmic | 40 to 60 | 21 ± 5 |
| Orbital | Carotid siphon | 60 to 80 | 47 ± 10 |
| Suboccipital | Vertebral | 40 to 85 | 38 ± 10 |
| Suboccipital | Basilar | above 80 | 41 ± 10 |
In about 10 to 20% of people no temporal window is usable. The pulsatility index is (systolic minus diastolic) divided by mean velocity, with a reference close to 1 (0.7 to 1.2 in the same review). The Lindegaard ratio is the middle cerebral velocity divided by the velocity in the ipsilateral extracranial internal carotid.
Sickle cell disease: STOP criteria
The 2020 ASH guideline recommends annual screening in children with HbSS or HbSβ0 aged 2 to 16 years. Classification uses the highest time-averaged maximum mean velocity (TAMM) in the distal internal carotid or middle cerebral artery. The 2016 UK standard organizes it as follows:
- Below 170 cm/s: normal, repeat in 1 year.
- 170 to 199 cm/s: conditional, repeat in 6 weeks to 3 months.
- 200 cm/s or more: abnormal, repeat within 1 week and discuss risk and transfusion.
- Anterior cerebral: 170 cm/s or more calls for early repeat; 200 cm/s or more is high risk.
- Middle cerebral below 70 cm/s, or below 50% of the contralateral side: also abnormal, possible occlusion; further imaging is needed.
In STOP, transfusion was indicated after two studies at 200 cm/s or more, or one above 220 cm/s, and it reduced stroke risk by more than 90%. The treatment decision belongs to hematology. A poor window makes the study non-diagnostic, and the UK standard points to MRI or MRA in that case.
Vasospasm after subarachnoid hemorrhage
Vasospasm usually appears from day 3, peaking between days 7 and 14 depending on the source. The bands below apply to the middle cerebral artery; severity labels differ across publications.
| Mean velocity (cm/s) | Lindegaard | Reading |
|---|---|---|
| Below 120 | Below 3 | No vasospasm criterion |
| 120 to 200 | 3 to 6 | Mild to moderate |
| Above 200 | Above 6 | Severe |
High velocity with a Lindegaard ratio below 3 favors a hyperdynamic state. In a 2026 meta-analysis, middle cerebral velocity had 76% sensitivity and 75% specificity; the Lindegaard ratio, 82% and 88%. Performance is lower in the other vessels, and validated pediatric thresholds are lacking.
What the report should include
- Indication, method (imaging or non-imaging) and windows that succeeded or failed.
- Velocity of each vessel, by side, stating whether it is TAMM or mean.
- In sickle cell disease: highest TAMM, vessel and STOP category.
- In vasospasm: day after the bleed, Lindegaard ratio and comparison with the prior study.
Common mistakes
- Applying vasospasm cut-offs to sickle cell disease, or the reverse.
- Reporting a study without an adequate window as normal.
- Ignoring a low velocity or asymmetry in a child with sickle cell disease.
See also our articles on carotid Doppler and transfontanelle ultrasound.
How Laudário helps
Laudário does not yet have a dedicated transcranial Doppler template. What exists today:
- Free form: the clinic registers the exam and the physician writes the title, description and impression.
- Carotid Doppler template, with vertebral and subclavian tabs, for the extracranial study.
Try it for 15 days free, no credit card required.
References
- Adams RJ, et al. STOP trial. N Engl J Med 1998;339:5-11.
- DeBaun MR, et al. ASH 2020 guidelines: cerebrovascular disease. Blood Adv 2020;4:1554-88.
- UK Forum on Haemoglobin Disorders. Transcranial Doppler Scanning for Children with Sickle Cell Disease: Standards and Guidance. 2nd ed. 2016.
- Point-of-Care Transcranial Doppler Sonography at the Intensive Care Unit. J Clin Med 2026;15:1630.
- Fujimoto, et al. Diagnostic accuracy of transcranial Doppler for cerebral vasospasm. Crit Care 2026;30.
Physician with an RQE specialty registration in general ultrasound. Writes on the Laudário blog about reports, classifications and standardization. Who writes and how.
Educational content for healthcare professionals. It does not replace clinical judgment or the guidelines adopted by your service. Editorial policy.