gms | German Medical Science

58. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e. V. (DGNC)

Deutsche Gesellschaft für Neurochirurgie (DGNC) e. V.

26. bis 29.04.2007, Leipzig

Intraoperative neurophysiological monitoring and mapping of motor cranial nerve nuclei on the floor of the fourth ventricle in patients with Arnold-Chiari II malformation

Intraoperatives neurophysiologisches Monitoring und Mappen der motorischen Hirnnervenkerne am Boden des 4. Ventrikels bei Patienten mit Arnold-Chiari-II-Malformation

Meeting Abstract

  • corresponding author J. Conrad - Klinik für Neurochirurgie, Universitätsklinikum Mainz
  • S. Welschehold - Klinik für Neurochirurgie, Universitätsklinikum Mainz
  • M. Schwarz - Klinik für Neurochirurgie, Universitätsklinikum Mainz
  • A. Reuland - Klinik für Neurochirurgie, Universitätsklinikum Mainz
  • A. Perneczky - Klinik für Neurochirurgie, Universitätsklinikum Mainz

Deutsche Gesellschaft für Neurochirurgie. 58. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC). Leipzig, 26.-29.04.2007. Düsseldorf: German Medical Science GMS Publishing House; 2007. DocSA.01.07

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/dgnc2007/07dgnc137.shtml

Veröffentlicht: 11. April 2007

© 2007 Conrad et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Objective: The Arnold-Chiari II malformation is found in nearly all patients with myelomeningoceles (MMC). This complex malformation involves the hindbrain, spine and skull and includes a downward dislocation of cerebellar structures, lower brainstem and fourth ventricle through the foramen magnum into the cervical canal. In this study somatosensory evoked potentials (SEPs) and particularly brainstem motor evoked potentials (MEPs) were recorded intraoperatively in patients with Arnold-Chiari II malformation. By mapping of the VII, IX-X, XI and XII cranial nerve motor nuclei on the floor of the fourth ventricle it is possible to show a caudal dislocation of these nuclei into the cervical canal. This is of great value to identify a safe intraoperative entry zone and intraoperative orientation.

Methods: Intraoperative neurophysiological monitoring (SEPs) and mapping of the motor cranial nerve nuclei on the surgically exposed floor of the fourth ventricle (MEPs) were recorded in 11 patients treated for symptomatic Arnold-Chiari II malformation. Mean age was 8 years and 2 months. Surgical strategy consists of craniospinal decompression with laminectomy C1 and partial laminectomy C2, fenestration of fourth ventricle and implantation of durapatch. In some cases also resection of rudimentary cerebellar tissue or choroid plexus was performed. During surgery, SEPs of the median nerve were monitored continuously. After opening of the fourth ventricle, MEPs were recorded of the VIIth, IXth-Xth, XIth and XIIth cranial nerves after bipolar stimulation.

Results: In 9 cases SEPs were not influenced by surgical manipulation, in one case the amplitude of SEPs became smaller during surgery, in another case SEPs were disturbed by artefacts. MEPs of IXth-Xth and XIIth cranial nerves were recorded in 7 cases, of XIth nerve in 4 cases and of the VIIth nerve in 2 cases. In one case no MEPs could be recorded. In two patients manipulation on the floor of the fourth ventricle had a cardiac effect with tachycardia or bradycardia and arrhythmia and stimulation was not possible. Mapping of VII, IX-X, XI and XII cranial nerve motor nuclei showed a dislocation of the nuclei into the cervical canal down to maximum C2.

Conclusions: In surgery of patients with Arnold-Chiari II malformation, the knowledge about the downward dislocation of cranial nerve motor nuclei is very important to improve surgical outcome. Manipulation of the brainstem at the level C2 can easily cause paresis of cranial nerves. If manipulation on these levels is necessary, mapping of cranial nerve motor nuclei will be of great value in the identification of safe entry zones.