gms | German Medical Science

Objective: Intraoperative microdoppler (IOMD), intraoperative Digital Substraction Angiography (iDSA), microscope integrated Indocyanine Green angiography (ICG) are methods that guide neurosurgical resection of arteriovenous malformations (AVM) to facilitate sequential dissection of first feeders and then veins. In this study authors are emphasizing the use of IOMD in AVM-surgery analysing the advantages and the limitations of this methode.

Method: In 32 AVM patients IOMD was evaluated according to a structured protocol. Supplying arteries and draining veins were analysed regarding haemodynamic profiles, flow velocities, pulsatility index (PI) and resistance index (RI). An angle of 60° between examined vessel and the probe was prespecified to achieve reliable, reproducible and comparable measurement. A post-operative DSA was performed in all patients.

Results: Supplying arterial blood vessels of AVMs could be identified by their characteristic blood flow profiles with PI<0.7 and RI<0.55. Venous drainages were accompanied by arterial blood flow disturbances which showed typical characteristics in all cases. Drainage veins in all 32 cases showed normalized venous flow patterns without arterial flow turbulences at the end of the surgical procedure. Postoperative DSA revealed a residual AVM in one patient.

Conclusions: IOMD constitutes a safe, accurate, and low cost imaging modality for evaluating blood flow velocities and for optimal, step-wise elimination avoiding premature sacrifice of veins. While PI and RI are reliable parameters in diagnosing cerebrovascular malformations, systolic and diastolic flow velocities may vary to a greater extent. This phenomena has never been elucidated previously and therefore needs to be emphasized when using this technique intraoperatively.