Using transcranial duplex sonography for monitoring vessel patency during surgery for intracranial aneurysms

A rapid noninvasive method to visualize ruptured aneurysms in the emergency room: three-dimensional power Doppler imaging

OBJECT

Three-dimensional (3D) power Doppler ultrasonography imaging provides a rapid, noninvasive visualization of ruptured intracranial aneurysms, including their relationship to other vascular structures.

METHODS

The authors used transcranial 3D power Doppler imaging in the emergency room to examine patients with acute subarachnoid hemorrhage. In all patients, the ruptured aneurysm was rapidly located with 3D power Doppler imaging. Conventional x-ray angiography confirmed both the ultrasonography-based diagnosis and the location of aneurysmal bleeding.

CONCLUSIONS

These preliminary results indicate that 3D power Doppler imaging is a rapid, noninvasive screening method for the visualization of ruptured aneurysms.

Cerebrovascular ultrasound

Rapid progress in noninvasive ultrasound techniques has resulted in a wide variety of clinical applications for assessment of both extracranial and intracranial arterial diseases. Recent highlights in cerebrovascular ultrasound research include imaging methods for characterization of intracranial aneurysms, use of echocontrast agents for improved evaluation of acute stroke patients and transient response harmonic imaging for depiction of brain perfusion. The important role of transcranial Doppler microembolism detection in carotid endarterectomy has been defined, new approaches to noninvasive Doppler measurement of intracranial pressure are progressing, and the clinical indications for transcranial Doppler monitoring of intracranial vasospasm to prevent secondary stroke have expanded. New functional transcranial Doppler applications, which are complementary to positron emission tomography and functional magnetic resonance imaging studies, are evolving for evaluation of functional recovery after stroke; investigation of perfusion asymmetries during complex spatial tasks; assessment of hemispheric dominance in surgical candidates for epilepsy surgery; and elucidation of temporal patterns of regional neuronal activity. With increasing sophistication of cerebrovascular ultrasound methodology, it is essential that standards for data acquisition and interpretation be established. Three recent consensus meetings have provided detailed recommendations on quantification of carotid artery stenosis, on characterization of carotid artery plaques and on microembolism detection by transcranial Doppler.

The value of transcranial duplex sonography in the management of patients subsequent to surgery for middle cerebral artery aneurysms

OBJECTIVE

We intended to evaluate the value of transcranial color-coded duplex sonography (TCCS) in the management of patients after clipping of an aneurysm of the middle cerebral artery. Question was whether this method was able to predict poor clinical outcome by detection of local circulation disorders in the postoperative course.

METHODS

A series of 15 consecutive patients was examined daily by TCCS. Special attention was paid to the branches of the middle cerebral artery distal from the clip (M2 branches). We correlated the TCCS results to the clinical outcome and occurrence of infarction on CCT.

RESULTS

In six patients, one or more M2 branches could not be found in the immediate postoperative course, but reappeared after a period of 1-12 days in five patients. The three patients with a missing signal for more than 4 days suffered from infarction of the dependent territory and permanent neurological deficit not due to vasospasm of the middle cerebral artery. In the nine patients with constant TCCS signals, there was only one infarction due to pre-hospital systemical hypotension.

CONCLUSION

TCCS cannot give exact postoperative information about incidental vessel occlusion during surgery for MCA aneurysms because M2 branches can remain invisible for some days without being occluded, but this invisibility seems to be coupled with ischemic complications.