gms | German Medical Science

62nd Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Polish Society of Neurosurgeons (PNCH)

German Society of Neurosurgery (DGNC)

7 - 11 May 2011, Hamburg

Intracranial air collections, brain shift, and the accuracy of stereotactic electrode implantion analyzed by intraoperative computertomography

Meeting Abstract

  • W. Hamel - Klinik für Neurochirurgie, Universitätsklinikum Hamburg-Eppendorf, Hamburg
  • D. Matzner - Klinik für Neurochirurgie, Universitätsklinikum Hamburg-Eppendorf, Hamburg
  • C. Moll - Institut für Neurophysiologie & Pathophysiologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg
  • C. Buhmann - Klinik für Neurologie, Universitätsklinikum Hamburg-Eppendorf, Hamburg
  • M. Westphal - Klinik für Neurochirurgie, Universitätsklinikum Hamburg-Eppendorf, Hamburg
  • J.A. Köppen - Klinik für Neurochirurgie, Universitätsklinikum Hamburg-Eppendorf, Hamburg

Deutsche Gesellschaft für Neurochirurgie. Polnische Gesellschaft für Neurochirurgen. 62. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgen (PNCH). Hamburg, 07.-11.05.2011. Düsseldorf: German Medical Science GMS Publishing House; 2011. DocMO.12.08

DOI: 10.3205/11dgnc093, URN: urn:nbn:de:0183-11dgnc0936

Published: April 28, 2011

© 2011 Hamel et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

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Objective: The effects of intraoperative air collections on brain shift and the precision of stereotactic electrode implantation is a matter of ongoing debate.

Methods: In 53 patients electrodes were implanted into the subthalamic nucleus (31), internal pallidum (12), or ventrolateral thalamus (9). Intraoperative CT scans obtained at the end of surgery were evaluated for the stereotactic electrode position, intracranial air collections, and the position of clearly identifiable anatomic landmarks (tip of lateral ventricles, pineal calcifications; and commissures were affected by electrode-induced artefacts).

Results: Air collections were found in 34 patients (mean volume 7.2 ml ± 13.7). The posterior shift of the tip of the lateral ventricles correlated with the volume of frontal air (r = 0.87; p < 0.0001). Only > 10 ml of air (n = 7) resulted in posterior ventricle shifts of more than 1.0 mm (mean 3.1 mm ± 1.9), which differed significantly from patients without or with less than 10 ml of air (p = 0.0001). Air collections that were restricted to or dominant in one hemisphere resulted in the increased shift of the ipsilateral ventricle. Pineal calcifications had shifted an average of 0.5 mm (± 0.7). In a few patients, anterior shift was noted and most patients revealed no shift (median 0 mm). The eucledian mean distance from the planned stereotactic target to the actual position of the electrodes was 2.2 mm (± 1.5). The deviation was highest in the direction of electrode implantation (i.e. error in depth; 1.7 mm, ± 1.6). The more critical lateral shift was 1.2 mm (± 0.8). In sterotactic coordinates the deviation was: x = 0.9 (± 0.8); y = 1.0 (± 1.0); z = 1.4 (± 1.4). In patients with intracranial air collections the average euclidan deviation was 2.2 mm (± 1.7) and did not differ from patients without air (2.4 ± 1.3 mm). Posterior shift of lateral ventricles of > 1 mm did not lead to (compensatory) selection of the posterior trajectory for permanent electrode implantation.

Conclusions: In contrast to what has been claimed, the overall accuracy of electrode implantation is not affected by even large air collections. Frontal air > 10 ml resulted in brain shift, which may affect the intracranial location of the anatomic target but this had no influence on trajectory selection. It is advisable to minimize the loss of CSF during stereotactic electrode implantation, although the effects of intracranial air collections < 10 ml on both stereotactic precision and the anatomic location of basal ganglia targets are negligible.