W. Jeff Elias
Volker A. Coenen and Cameron C. McIntyre
Nader Pouratian, Davis L. Reames, Robert Frysinger, and W. Jeff Elias
The aim of this study was to assess risk factors for postoperative seizures after deep brain stimulation (DBS) lead implantation surgery and the impact of such seizures on length of stay and discharge disposition.
The authors reviewed a consecutive series of 161 cases involving patients who underwent implantation of 288 electrodes for treatment of movement disorders at a single institution to determine the absolute risk of postoperative seizures, to describe the timing and type of seizures, to identify statistically significant risk factors for seizures, and to determine whether there are possible indications for seizure prophylaxis after DBS lead implantation. The electronic medical records were reviewed to identify demographic details, medical history, operative course, and postoperative outcomes and complications. To evaluate significant associations between potential risk factors and postoperative seizures, both univariate and multivariate analyses were performed.
Seven (4.3%) of 161 patients experienced postoperative seizures, all of which were documented to have been generalized tonic-clonic seizures. In 5 (71%) of 7 cases, patients only experienced a single seizure. Similarly, in 5 of 7 cases, patients experienced seizures within 24 hours of surgery. In 6 (86%) of the 7 cases, seizures occurred within 48 hours of surgery. Univariate analysis identified 3 significant associations (or risk factors) for postoperative seizures: abnormal findings on postoperative imaging (hemorrhage, edema, and or ischemia; p < 0.001), age greater than 60 years (p = 0.021), and transventricular electrode trajectories (p = 0.023). The only significant factor identified on multivariate analysis was abnormal findings on postoperative imaging (p < 0.0001, OR 50.4, 95% CI 5.7–444.3). Patients who experienced postoperative seizures had a significantly longer length of stay than those who were seizure free (mean ± SD 5.29 ± 3.77 days vs 2.38 ± 2.38 days; p = 0.002, Student 2-tailed t-test). Likewise, final discharge to home was significantly less likely in patients who experienced seizures after implantation (43%) compared with those patients who did not (92%; p = 0.00194, Fisher exact test).
These results affirm that seizures are an uncommon complication of DBS surgery and generally occur within 48 hours of surgery. The results also indicate that hemorrhage, edema, or ischemia on postoperative images (“abnormal” imaging findings) increases the relative risk of postoperative seizures by 30- to 50-fold, providing statistical credence to the long-held assumption that seizures are associated with intracranial vascular events. Even in the setting of a postimplantation imaging abnormality, long-term anticonvulsant therapy will not likely be required because none of our patients developed chronic epilepsy.
W. Jeff Elias and G. Rees Cosgrove
Report of two cases
Mark Quigg, David S. Geldmacher, and W. Jeff Elias
✓ Assessment of eloquent functions during brain mapping usually relies on testing reading, speech, and comprehension to uncover transient deficits during electrical stimulation. These tests stem from findings predicted by the Geschwind–Wernicke hypothesis of receptive and expressive cortices connected by white matter tracts. Later work, however, has emphasized cortical mechanisms of language function. The authors report two cases that demonstrate that conduction aphasia is cortically mediated and can be inadequately assessed if not specifically evaluated during brain mapping.
To determine the distribution of language on the dominant cortex, electrical cortical stimulation was performed in two cases by using implanted subdural electrodes during brain mapping before epilepsy surgery. A transient isolated deficit in repetition of language was reported during stimulation of the posterior portion of the dominant superior temporal gyrus in one patient and during stimulation of the supramarginal gyrus in the other patient.
These cases demonstrate a localization of language repetition to the posterior perisylvian cortex. Brain mapping of this region should include assessment of verbal repetition to avoid potential deficits resembling conduction aphasia.
W. Jeff Elias, Charles A. Sansur, and Robert C. Frysinger
The authors analyzed deep brain stimulation electrode trajectories on MR images to identify risks of cerebrovascular complications associated with the number of electrode insertions, traversal of a sulcus, and penetration of the ventricle.
Pre- and postoperative MR volumes were fused to determine the proximity of electrodes to a sulcus or ventricle and whether there were cortical, subcortical, or intraventricular complications. Complications were further classified as hemorrhagic or nonhemorrhagic and symptomatic or asymptomatic. The authors examined 258 electrode implantation for deep brain stimulation. There were 4 symptomatic events (1.6% incidence): 3 hemorrhagic and 1 nonhemorrhagic, all within the cortex. Asymptomatic events included cortical hemorrhage in 1 patient, nonhemorrhagic cortical changes in 6, pallidal hemorrhage in 1, thalamic infarction in 1, and intraventricular hemorrhage (IVH) in 5 patients.
Proximity to a sulcus was a significant risk factor for hemorrhagic and nonhemorrhagic cortical complications (p = 0.001). There was a complication rate of 10.1% within the trajectories penetrating or adjacent to a sulcus, and a 0.7% rate with trajectories clearly positioned within the gyrus. Asymptomatic IVH was observed in 5% of ventricular penetrations. A history of hypertension was a risk factor for cortical hemorrhage (p = 0.019), but not for cortical ischemic/edematous events (p = 0.605). The number of electrode penetrations did not differ between patients with and without complications (p = 0.868), and the sequence of electrode insertions was not a risk factor in bilateral surgeries.
Symptomatic cortical complications occur when electrodes traverse close to a sulcus. Asymptomatic IVH occurs infrequently with ventricular penetration. Despite intraoperative efforts to avoid cortical sulci, a higher than expected incidence of electrode proximity to the sulci was identified on careful postoperative trajectory analysis. This finding emphasizes the importance of assiduously planning trajectories and reviewing cases with thorough MR analysis.
W. Jeff Elias, Dibyendu Kumar Ray, and John A. Jane Sr.
Dr. Lennart Heimer, the famous neuroanatomist of Swedish descent, died last year but left a legacy that will impact the neurosciences and potentially psychosurgery for years to come. He developed an anatomical technique for demonstrating the terminal boutons that helped to delineate basal forebrain anatomy. During these studies, he realized the relationship of basal forebrain structures to the limbic system, thus initiating the concept of the ventral striatum and parallel basal ganglia circuitry.
Heimer excelled as a teacher as well and honed his brain dissection technique to one of the most effective tools for understanding neuroanatomy. His legendary sessions with neurosurgical residents resulted in his recognition as one of the world’s leading fiber tract dissectors. His gentle, engaging manner has been documented in several media formats.
Stephen Monteith, Jason Sheehan, Ricky Medel, Max Wintermark, Matthew Eames, John Snell, Neal F. Kassell, and W. Jeff Elias
Magnetic resonance–guided focused ultrasound surgery (MRgFUS) has the potential to create a shift in the treatment paradigm of several intracranial disorders. High-resolution MRI guidance combined with an accurate method of delivering high doses of transcranial ultrasound energy to a discrete focal point has led to the exploration of noninvasive treatments for diseases traditionally treated by invasive surgical procedures. In this review, the authors examine the current intracranial applications under investigation and explore other potential uses for MRgFUS in the intracranial space based on their initial cadaveric studies.