Brain shift during bur hole–based procedures using interventional MRI

Abstract

Object. Brain shift during minimally invasive, bur hole-based procedures such as deep brain stimulation (DBS) electrode implantation and stereotactic brain biopsy is not well characterized or understood. We examine shift in various regions of the brain during a novel paradigm of DBS electrode implantation using interventional imaging throughout the procedure with high-field interventional MRI.Methods. Serial MR images were obtained and analyzed using a 1.5-T magnet prior to, during, and after the placement of DBS electrodes via frontal bur holes in 44 procedures. Three-dimensional coordinates in MR space of unique superficial and deep brain structures were recorded, and the magnitude, direction, and rate of shift were calculated. Measurements were recorded to the nearest 0.1 mm.Results. Shift ranged from 0.0 to 10.1 mm throughout all structures in the brain. The greatest shift was seen in the frontal lobe, followed by the temporal and occipital lobes. Shift was also observed in deep structures such as the anterior and posterior commissures and basal ganglia; shift in the pallidum and subthalamic region ipsilateral to the bur hole averaged 0.6 mm, with 9% of patients having over 2 mm of shift in deep brain structures. Small amounts of shift were observed during all procedures; however, the initial degree of shift and its direction were unpredictable.Conclusions. Brain shift is continual and unpredictable and can render traditional stereotactic targeting based on preoperative imaging inaccurate even in deep brain structures such as those used for DBS. This article contains some figures that are displayed in color on line but in black-and-white in the print edition.M. E. Ivan et al. 150J Neurosurg / Volume 121 / July 2014 pressure) or to mechanical force on the brain resulting from the intracranial passage of guidance catheters. Methods Patient Selection and DemographicsA total of 39 patients underwent 47 consecutive operations for implantation of a deep brain stimulator for either Parkinson's disease (PD) or dystonia at the University of California, San Francisco (UCSF) Medical Center. These patients underwent unilateral or bilateral placement of their DBS electrodes via a bur hole procedure. Table 1 shows the patient population, procedure, location, target, and disease process. Three surgeries were excluded from the analysis. One patient was intentionally moved between MRI sequences, invalidating the methodology used to assess brain shift. In 2 additional cases, data were analyzed but the control values for fixed points in the cranium were above our acceptable threshold (> 0.5 mm, see below). Therefore, 44 separate operations were included in this study. Six patients were operated on twice either due to staged unilateral placement of stimulators (5 patients) or replacement of stimulators after infection (1 patient). The average age at the time of surgery was 58 ± 13 years old, and 48% of the patients were female. Fifteen patients had unilateral stimulator placement and 29 had bilateral placement. The target was t...

Asleep Deep Brain Stimulation Reduces Incidence of Intracranial Air during Electrode Implantation

“…Quantification of shift of these structures is important; the correlation between shift in cortical surface and deep brain structures per se is weak [31], but other studies have shown that this correlation is statistically significant [17]. The focus of this study, however, was largely on the incidence of air in aDBS versus wkDBS, with the contention that reducing the incidence of pneumocephalus should mitigate its adverse effects.…”

Clinical outcomes using ClearPoint interventional MRI for deep brain stimulation lead placement in Parkinson’s disease

“…ClearPoint uses real-time MRI to perform target selection and monitor lead placement; it does not rely on MR images obtained preoperatively, which cannot account for intraoperative brain shift due to pneumocephalus, or CT images obtained intraoperatively, which must be fused with preoperative image sets and are therefore subject to potential fusion errors. 13,14 It therefore has the advantage of detecting lead placement errors as well as other intraoperative complications such as hemorrhages in real time, with shorter operative times than awake surgery. Finally, because iMRI DBS can be safely done under general anesthesia and does not require withholding of parkinsonian medications, it may broaden the accessibility to those who might not otherwise be able to tolerate awake surgery.…”

Improving outcomes of subthalamic nucleus deep brain stimulation in Parkinson’s disease

“…Thus, STN DBS is typically performed under local anesthesia to allow MER and physiologic testing in an awake patient. Finally, brain shift due to loss of CSF from the dural opening should be minimized with the use of dural sealants [37].…”