Revisiting the rules for freehand ventriculostomy: a virtual reality analysis.

Raabe, Clemens; Fichtner, Jens; Beck, Jürgen; Gralla, Jan; Raabe, Andreas (2018). Revisiting the rules for freehand ventriculostomy: a virtual reality analysis. Journal of neurosurgery, 128(4), pp. 1250-1257. American Association of Neurological Surgeons 10.3171/2016.11.JNS161765

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OBJECTIVE Frontal ventriculostomy is one of the most frequent and standardized procedures in neurosurgery. However, many first and subsequent punctures miss the target, and suboptimal placement or misplacement of the catheter is common. The authors therefore reexamined the landmarks and rules to determine the entry point and trajectory with the best hit rate (HtR). METHODS The authors randomly selected CT scans from their institution's DICOM pool that had been obtained in 50 patients with normal ventricular and skull anatomy and without ventricular puncture. Using a 5 × 5-cm frontal grid with 25 entry points referenced to the bregma, the authors examined trajectories 1) perpendicular to the skull, 2) toward classic facial landmarks in the coronal and sagittal planes, and 3) toward an idealized target in the middle of the ipsilateral anterior horn (ILAH). Three-dimensional virtual reality ventriculostomies were simulated for these entry points; trajectories and the HtRs were recorded, resulting in an investigation of 8000 different virtual procedures. RESULTS The best HtR for the ILAH was 86% for an ideal trajectory, 84% for a landmark trajectory, and 83% for a 90° trajectory, but only at specific entry points. The highest HtRs were found for entry points 3 or 4 cm lateral to the midline, but only in combination with a trajectory toward the contralateral canthus; and 1 or 2 cm lateral to the midline, but only paired with a trajectory toward the nasion. The same "pairing" exists for entry points and trajectories in the sagittal plane. For perpendicular (90°) trajectories, the best entry points were at 3-5 cm lateral to the midline and 3 cm anterior to the bregma, or 4 cm lateral to the midline and 2 cm anterior to the bregma. CONCLUSIONS Only a few entry points offer a chance of a greater than 80% rate of hitting the ILAH, and then only in combination with a specific trajectory. This "pairing" between entry point and trajectory was found both for landmark targeting and for perpendicular trajectories, with very limited variability. Surprisingly, the ipsilateral medial canthus, a commonly reported landmark, had low HtRs, and should not be recommended as a trajectory target.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurosurgery 04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic and Interventional Neuroradiology
UniBE Contributor:	Fichtner, Jens, Beck, Jürgen, Gralla, Jan, Raabe, Andreas
Subjects:	600 Technology > 610 Medicine & health
ISSN:	0022-3085
Publisher:	American Association of Neurological Surgeons
Language:	English
Submitter:	Martin Zbinden
Date Deposited:	08 Aug 2017 09:12
Last Modified:	05 Dec 2022 15:05
Publisher DOI:	10.3171/2016.11.JNS161765
PubMed ID:	28524798
Uncontrolled Keywords:	CLV = contralateral ventricle; CMC = contralateral medial canthus; HtR = hit rate; ILAH = ipsilateral anterior horn; ILPC = ipsilateral pars centralis; IMC = ipsilateral medial canthus; Kocher’s point; external ventricular drainage; hydrocephalus; surgical technique; ventriculostomy; virtual reality
URI:	https://boris.unibe.ch/id/eprint/100898