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Hemodynamic and electrophysiological evaluation following extracranial/intracranial bypass surgery
G Dorfmüller1, W P Sollmann, M Lorenz
1Neurosurgical Clinic, Medical University Hannover, Fed. Rep. of Germany.
Insights
Transcranial Doppler sonography reliably assesses intracranial blood flow after bypass surgery. This noninvasive technique confirms bypass patency and evaluates blood flow dynamics, aiding surgical outcomes.
Area of Science:
- Neurosurgery
- Vascular Surgery
- Neurology
Background:
- Extracranial/intracranial bypass surgery is crucial for managing cerebrovascular diseases.
- Assessing the patency and hemodynamic impact of these bypasses is essential for patient outcomes.
Purpose of the Study:
- To evaluate the efficacy of transcranial Doppler (TCD) sonography with flow mapping in assessing intracranial hemodynamics post-bypass surgery.
- To compare TCD findings with somatosensory evoked potentials (SSEPs) and electroencephalogram (EEG) analysis.
Main Methods:
- Fifty patients undergoing extracranial/intracranial bypass were studied.
- Transcranial Doppler sonography, blood flow mapping, SSEPs, and computer-assisted EEG were utilized.
- Temporary compression of the supplying vessel was performed to assess bypass response.
Main Results:
- TCD identified nonpatent bypasses in 4 patients.
- The majority of patients showed bypass-mediated retrograde flow in the middle cerebral artery (MCA).
- Retrograde flow was observed in the M1 segment of the MCA in 9 patients; A1 segment was insonated in most.
Conclusions:
- Transcranial Doppler sonography is a reliable, noninvasive method for assessing intracranial hemodynamics after bypass surgery.
- TCD provides valuable information on bypass patency and blood flow dynamics.
- Minimal alterations in SSEPs and EEG were noted during bypass compression, highlighting TCD's sensitivity.
Abstract:
We examined 50 patients with an extracranial/intracranial bypass using transcranial Doppler blood flow mapping, somatosensory evoked potentials, and computer-assisted EEG analysis. The investigation was supplemented by temporary compression of the extracranial supplying vessel. Transcranial Doppler sonography revealed in addition to 4 patients with nonpatent anastomoses, a bypass-mediated retrograde flow in the ipsilateral middle cerebral artery beyond a depth of 40 mm in the majority of patients. In 9 patients, retrograde flow could be demonstrated in the whole proximal (M1) MCA segment. The precommunicating segment of the anterior cerebral artery (A1) could be reliably insonated in all but 5 patients. Bypass-compression dependent alterations in the SSEP and in EEG analysis were only observed in a small number of patients. Transcranial Doppler sonography, with the aid of the flow mapping system, appears therefore, to be a reliable and repeatedly performable noninvasive technique for the assessment of intracranial hemodynamics following bypass surgery.