title: Neuronavigated microvascular Doppler sonography for intraoperative monitoring of blood flow velocity changes during aneurysm surgery - a feasible monitoring technique.
abstract: OBJECTIVE
  The intraoperative microvascular Doppler sonography (iMDS) is a well-established tool in vascular surgery for blood flow velocity (BFV) monitoring, capable of detecting vessel occlusion. However, identification of subtotal vessel compromise is more difficult, since the measured BFV may substantially vary with changing insonation angles and insonated vessel segments. To keep these parameters constant we combined neuronavigation with iMDS (niMDS). The question was if niMDS allows the detection of subtotal vessel compromise in aneurysm surgery.
  
  
  METHODS
  During surgery, the 3-dimensional reconstruction of the CT-angiography, which was obtained routinely prior to surgery, was displayed by the neuronavigational system. Prior to clipping, neuronavigation was used to define target point and trajectory, which, by coupling the neuronavigational pointer with the Doppler probe, correspond to the insonated vessel segment and the insonation angle. After clipping, for each vessel segment, the same trajectory was used for all consecutive measurements. The mean BFVs pre- and post-clipping were documented.
  
  
  RESULTS
  We performed 82 BFV-measurements in 39 aneurysm surgeries. Mean deviation between pre- and post-clipping BFV values was 2.12cm/s. There was a significant correlation between the mean BFV values before and after clipping (r=0.45 [95% CI 17-66%]; p=0.002). One patient experienced new neurological deficits due to occlusion of a perforating vessel that was not insonated.
  
  
  CONCLUSIONS
  The study could not answer the question if niMDS can detect BFV changes after clipping indicating vessel compromise, as no subtotal vessel occlusion occurred in the 39 operations. However, we proofed that niMDS-measured BFVs only varied minimally in uncompromised vessels pre- and post-clipping, suggesting that vessel compromises might be easily detected during aneurysm surgery.
authors.affiliation: Department of Neurosurgery, Georg August University Göttingen, Germany. Electronic address: vesna.malinova@gmail.com.
authors.forename: Vesna
authors.initials: V
authors.lastname: Malinova
authors.affiliation: Department of Neurosurgery, Georg August University Göttingen, Germany.
authors.forename: Kajetan
authors.initials: K
authors.lastname: von Eckardstein
authors.affiliation: Department of Neurosurgery, Georg August University Göttingen, Germany.
authors.forename: Veit
authors.initials: V
authors.lastname: Rohde
authors.affiliation: Department of Neurosurgery, Georg August University Göttingen, Germany.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Mielke
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D002533:Cerebral Angiography / Q000379:methods; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000601:surgery*; D008297:Male; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D038361:Neuronavigation / Q000379:methods; D014656:Vascular Surgical Procedures / Q000379:methods
keywords: Aneurysm surgery; Microvascular Doppler; Neuronavigation