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Transcranial Doppler pulsatility in vasodilation and stenosis
C A Giller1, K Hodges, H H Batjer
1Department of Neurological Surgery, University of Texas Southwestern Medical School, Dallas.
Journal of Neurosurgery
|June 1, 1990
Summary
Transcranial Doppler (TCD) pulsatility can differentiate between intracranial stenosis and reduced downstream resistance. A greater pulsatility drop with increased velocity indicates reduced resistance, aiding blood flow interpretation.
Area of Science:
- Neurosonology
- Cerebrovascular Physiology
- Medical Ultrasound
Background:
- Transcranial Doppler (TCD) ultrasound measures intracranial blood velocity.
- Interpreting TCD velocity changes is complex, as increases can indicate stenosis or reduced downstream resistance.
- These two mechanisms have different implications for cerebral blood flow.
Purpose of the Study:
- To investigate if TCD pulsatility can distinguish between local stenosis and decreased downstream resistance in intracranial vessels.
- To compare pulsatility changes in models and patients with known conditions.
Main Methods:
- Used an artificial vascular model to simulate stenosis and distal dilation.
- Collected Doppler ultrasonic readings from the model.
- Reviewed TCD studies of patients with arteriovenous malformations (AVMs) and aneurysmal vasospasm.
- Compared pulsatility in AVMs (decreased resistance) versus vasospasm (stenosis).
Main Results:
- The model showed a significantly greater pulsatility drop per velocity increase in vasodilation (0.38) compared to stenosis (0.20).
- Patient data revealed a higher pulsatility drop in AVMs (0.67) versus vasospasm (0.26).
- These differences were statistically significant (p < 0.05).
Conclusions:
- The fall in TCD pulsatility relative to a velocity increase is significantly greater when caused by diminished downstream resistance than by stenosis.
- TCD pulsatility is a valuable parameter for differentiating the causes of elevated intracranial blood velocity.