BACKGROUND: Accurate electrode position is important for the efficacy of deep brain stimulation (DBS). Several reports revealed errors during stereotactic surgery due to cerebrospinal fluid (CSF) loss and subdural air invasion. Because subdural air resolves in the weeks after surgery and the brain returns to its original position, DBS electrodes may become displaced postoperatively.
OBJECTIVE: To quantitatively assess postoperative DBS electrode displacement in relation to subdural air invasion.
METHODS: We retrospectively analyzed 14 patients with advanced Parkinson disease and subthalamic nucleus DBS electrodes that underwent immediate postoperative frame-based stereotactic computer tomography (CT) and repeated CT after longer follow-up. We performed volumetric measurements of postoperative subdural air collections on both sides of the brain and determined stereotactic coordinates of the deepest DBS contact on the direct postoperative and follow-up CT.
RESULTS: Subdural air collections measured on average 17 ± 24 cm3. Consequently, the frontal cortex shifted posteriorly. On follow-up imaging after 16 ± 8 months, air collections had resolved and the frontal cortex had returned to its original position, causing anterior curving of the electrodes. The electrodes moved on average 3.3 ± 2.5 mm upward along the trajectory. This displacement significantly correlated with the amount of postoperative subdural air.
CONCLUSION: Considerable displacement of DBS electrodes may occur in the weeks following surgery, especially in cases with large postoperative subdural air volumes. Postoperative documentation of electrode localization should therefore be repeated after longer follow-up.
Department of Neurosurgery, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands (Munckhof) (Schuurman)
Department of Neurology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands (Contarino) (Speelman) (Bie)
Department of Clinical Neurophysiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands (Bour)
Reprint requests: Pepijn van den Munckhof, MD, Department of Neurosurgery H2–241, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. E-mail: firstname.lastname@example.org
Received, March 13, 2009.
Accepted, December 4, 2009.