Perioperative complications of deep brain stimulation among patients with advanced age

J Neurosurg 135:1421–1428, 2021

Deep brain stimulation (DBS) is an elective procedure that can dramatically enhance quality of life. Because DBS is not considered lifesaving, it is important that providers produce consistently good outcomes, and one factor they usually consider is patient age. While older age may be a relative contraindication for some elective surgeries, the progressive nature of movement disorders treated with DBS may suggest that older patients stand to benefit substantially from surgery. To better understand the risks of treating patients of advanced age with DBS, this study compares perioperative complication rates in patients ≥ 75 to those < 75 years old.

METHODS Patients undergoing DBS surgery for various indications by a single surgeon (May 2013–July 2019) were stratified into elderly (age ≥ 75 years) and younger (age < 75 years) cohorts. The risks of common perioperative complications and various outcome measures were compared between the two age groups using risk ratios (RRs) and 95% confidence intervals (CIs).

RESULTS A total of 861 patients were available for analysis: 179 (21%) were ≥ 75 years old and 682 (79%) were < 75 years old (p < 0.001). Patients ≥ 75 years old, compared with those < 75 years old, did not have significantly different RRs (95% CIs) of seizure (RR 0.4, 95% CI 0.1–3.3), cerebrovascular accident (RR 1.9, 95% CI 0.4–10.3), readmission within 90 days of discharge (RR 1.22, 95% CI 0.8–1.8), explantation due to infection (RR 2.5, 95% CI 0.4–15.1), or surgical revision (for lead, RR 2.5, 95% CI 0.4–15.1; for internal pulse generator, RR 3.8, 95% CI 0.2–61.7). Although the risk of postoperative intracranial bleeding was higher in the elderly group (6.1%) than in the younger group (3.1%), this difference was not statistically significant (p = 0.06). However, patients ≥ 75 years old did have significantly increased risk of altered mental status (RR 2.5, 95% CI 1.6–4.0), experiencing more than a 1-night stay (RR 1.7, 95% CI 1.4–2.0), and urinary retention (RR 2.3, 95% CI 1.2–4.2; p = 0.009).

CONCLUSIONS Although elderly patients had higher risks of certain outcome measures than younger patients, this study showed that elderly patients undergoing DBS for movement disorders did not have an increased risk of more serious complications, such as intracranial hemorrhage, infection, or readmission. Advanced age alone should not be considered a contraindication for DBS.

Postmortem Dissections of Common Targets for Lesion and Deep Brain Stimulation Surgeries

Neurosurgery 86:860–872, 2020

The subthalamic nucleus (STN), globus pallidus internus (GPi), and pedunculopontine nucleus (PPN) are effective targets for deep brain stimulation (DBS) in many pathological conditions. Previous literature has focused on appropriate stimulation targets and their relationships with functional neuroanatomic pathways; however, comprehensive anatomic dissections illustrating these nuclei and their connections are lacking. This information will provide insight into the anatomic basis of stimulation-induced DBS benefits and side effects.

OBJECTIVE: To combine advanced cadaveric dissection techniques and ultrahigh field magnetic resonance imaging (MRI) to explore the anatomy of the STN, GPi, and PPN with their associated fiber pathways.

METHODS: A total of 10 cadaveric human brains and 2 hemispheres of a cadaveric head were examined using fiber dissection techniques. The anatomic dissections were compared with 11.1 Tesla (T) structural MRI and 4.7 T MRI fiber tractography.

RESULTS: The extensive connections of the STN (caudate nucleus, putamen, medial frontal cortex, substantia innominata, substantia nigra, PPN, globus pallidus externus (GPe), GPi, olfactory tubercle, hypothalamus, and mammillary body) were demonstrated. The connections of GPi to the thalamus, substantia nigra, STN, amygdala, putamen, PPN, and GPe were also illustrated. The PPN was shown to connect to the STN and GPi anteriorly, to the cerebellum inferiorly, and to the substantia nigra anteriorly and superiorly.

CONCLUSION: This study demonstrates connections using combined anatomic microdissections, ultrahigh field MRI, and MRI tractography. The anatomic findings are analyzed in relation to various stimulation-induced clinical effects. Precise knowledge of neuroanatomy, anatomic relationships, and fiber connections of the STN, GPi, PPN will likely enable more effective targeting and improved DBS outcomes.

Stereotactic Lesion in the Forel’s Field H: A Two-Years Prospective Open-Label Study on Motor and Nonmotor Symptoms, Neuropsychological Functions and Quality of Life in Parkinson Disease

Neurosurgery, Volume 85, Issue 4, October 2019, Pages E650–E659

Stereotactic lesion in the Forel’s field H (campotomy) was proposed in 1963 to treat Parkinson disease (PD) symptoms. Despite its rationale, very few data on this approach have emerged. Additionally, no study has assessed its effects on nonmotor symptoms, neuropsychological functions and quality of life.

OBJECTIVE: To provide a prospective 2-yr assessment of motor, nonmotor, neuropsychological and quality of life variables after unilateral campotomy.

METHODS: Twelve PD patients were prospectively evaluated using the Unified Parkinson’s Disease Rating Scale (UPDRS), the Dyskinesia Rating Scale and the Parkinson’s disease quality of life questionnaire (PDQ39) before campotomy, and after 6 and 24 mo. Nonmotor, neuropsychiatric, neuropsychological and quality of life variables were assessed. The impact of PD on global health was also rated.

RESULTS: A significant reduction in contralateral rest tremor (65.7%, P < .001), rigidity (87.8%, P < .001), bradykinesia (68%, P < .001) and axial symptoms (24.2%, P < .05) in offmedication condition led to a 43.9% reduction in UPSDRS III scores 2 yr after campotomy (P < .001). Gait improved by 31.9% (P < .05) and walking time to cover 7 m was reduced by 43.2% (P< .05). Pain decreased by 33.4% (P< .01), while neuropsychiatric and neuropsychological functions did not change. Quality of life improved by 37.8% (P < .05), in line with a 46.7% reduction of disease impact on global health (P < .001).

CONCLUSION: A significant 2-yr improvement of motor symptoms, gait performance and pain was obtained after unilateral campotomy without significant changes to cognition. Quality of life markedly improved in parallel with a significant reduction of PD burden on global health.

Role of Biomarkers in Adaptive Modulation of Clinical Brain Stimulation

Neurosurgery, Volume 85, Issue 3, September 2019:  E430–E439

Therapeutic brain stimulation has proven efficacious for treatment of nervous system diseases, exerting widespread influence via disease-specific neural networks. Activation or suppression of neural networks could theoretically be assessed by either clinical symptom modification (ie, tremor, rigidity, seizures) or development of specific biomarkers linked to treatment of symptomatic disease states.

For example, biomarkers indicative of disease state could aid improved intraoperative localization of electrode position, optimize device efficacy or efficiency through dynamic control, and eventually serve to guide automatic adjustment of stimulation settings.

Biomarkers to control either extracranial or intracranial stimulation span from continuous physiological brain activity, intermittent pathological activity, and triggered local phenomena or potentials, to wearable devices, blood flow, biochemical or cardiac signals, temperature perturbations, optical or magnetic resonance imaging changes, or optogenetic signals.

The goal of this review is to update new approaches to implement control of stimulation through relevant biomarkers. Critical questions include whether adaptive systems adjusted through biomarkers can optimize efficiency and eventually efficacy, serve as inputs for stimulation adjustment, and consequently broaden our fundamental understanding of abnormal neural networks in pathologic states.

Neurosurgeons are at the forefront of translating and developing biomarkers embedded within improved brain stimulation systems. Thus, criteria for developing and validating biomarkers for clinical use are important for the adaptation of device approaches into clinical practice.

Subthalamic deep brain stimulation under general anesthesia and neurophysiological guidance while on dopaminergic medication

Acta Neurochirurgica (2018) 160:823–829

The authors have previously reported on the technical feasibility of subthalamic nucleus deep brain stimulation (STN DBS) under general anesthesia (GA) with microelectrode recording (MER) guidance in Parkinsonian patients who continued dopaminergic therapy until surgery. This paper presents the results of a prospective cohort analysis to verify the outcome of the initial study, and report on wider aspects of clinical outcome and postoperative recovery. Methods All patients in the study group continued dopaminergic therapy until GA was administered. Baseline characteristics, intraoperative neurophysiological markers, and perioperative complications were recorded. Long-term outcome was assessed using selective aspects of the unified Parkinson’s disease rating scale motor score. Immediate postoperative recovery from GA was assessed using the Btime needed for extubation^ and Btotal time of recovery.^ Data for the Bstudy group^ was collected prospectively. Examined variables were compared between the Bstudy group^ and Bhistorical control group^ who stopped dopaminergic therapy preoperatively. Results The study group, n = 30 (May 2014–Jan 2016), were slightly younger than the Bcontrol group,^ 60 (51–64) vs. 64 (56– 69) years respectively, p = 0.043. Both groups were comparable for the recorded intraoperative neurophysiological parameters;number of MER tracks: 60% of the study group had single track vs. 58% in the control group, p = 1.0. Length of STN MER detected was 9 vs. 7 mm (median) respectively, p = 0.037. A trend towards better recovery from GA in the study group was noted, with shorter total recovery time: 60 (50–84) vs. 89 (62–120) min, p = 0.09. Long-term improvement in motor scores and reduction in L-dopa daily equivalent dose were equally comparable between both groups. No cases of dopamine withdrawal or problems with immediate postop dyskinesia were recorded in the on medications group. The observed rate of dopamine withdrawal side effects in the off-medications group was 15%.

Conclusions The continuation of dopaminergic treatment for patients with PD does not affect the feasibility/outcome of the STN DBS surgery. This strategy appears to reduce the risk of dopamine-withdrawal adverse effects and may improve the recovery in the immediate postoperative period, which would help enhance patients’ perioperative experience.


Optimization of Microelectrode Recording in Deep Brain Stimulation Surgery Using Intraoperative Computed Tomography

WORLD NEUROSURGERY 103: 168-173, JULY 2017

Microelectrode recording (MER) is used to confirm targeting accuracy during deep brain stimulation (DBS) surgery. We describe a technique using intraoperative computed tomography (CT) extrapolation (iCTE) to predetermine and adjust the trajectory of the guide tube to improve microelectrode targeting accuracy. We hypothesized that this technique would decrease the number of MER tracks and operative time, while increasing the recorded length of the subthalamic nucleus (STN).

– METHODS: Thirty-nine patients with Parkinson’s disease who underwent STN DBS before the iCTE method were compared with 33 patients undergoing STN DBS using iCTE. Before dural opening, a guide tube was inserted and rested on dura. Intraoperative computed tomography (iCT) was performed, and a trajectory was created along the guide tube and extrapolated to the target using targeting software. If necessary, headstage adjustments were made to correct for error. The guide tube was inserted, and MER was performed. iCT was performed with the microelectrode tip at the target. Coordinates were compared with planned/ adjusted track coordinates. Radial error between the MER track and the planned/adjusted track was calculated. Cases before and after implementation of iCTE were compared to determine the impact of iCTE on operative time, number of MER tracks and recorded STN length.

– RESULTS: The use of iCTE reduced the average radial MER track error from 1.90  0.12 mm (n[54) to 0.84  0.09 mm (n[49) (P < 0.001) while reducing the operative time for bilateral lead placement from 272  9 minutes (n [ 30) to 233  10 minutes (n [ 24) (P < 0.001). The average MER tracks per hemisphere was reduced from 2.24  0.13 mm (n[66) to 1.75  0.09 mm (n[63) (P < 0.001), whereas the percentage of hemispheres requiring a single MER track for localization increased from 29% (n [ 66) to 43% (n [ 63). The average length of recorded STN increased from 4.01  0.3 mm (n [ 64) to 4.75  0.28 mm (n [ 56) (P < 0.05).

-CONCLUSION: iCTE improves microelectrode accuracy and increases the first-pass recorded length of STN, while reducing operative time. Further studies are needed to determine whether this technique leads to less morbidity and improved clinical outcomes.


Probabilistic versus deterministic tractography for delineation of the cortico-subthalamic hyperdirect pathway in patients with Parkinson disease selected for deep brain stimulation

J Neurosurg 126:1657–1668, 2017

Diffusion-weighted MRI (DWI) and tractography allows noninvasive mapping of the structural connections of the brain, and may provide important information for neurosurgical planning. The hyperdirect pathway, connecting the subthalamic nucleus (STN) with the motor cortex, is assumed to play a key role in mediating the effects of deep brain stimulation (DBS), which is an effective but poorly understood treatment for Parkinson disease. This study aimed to apply recent methodological advances in DWI acquisition and analysis to the delineation of the hyperdirect pathway in patients with Parkinson disease selected for surgery.

METHODS High spatial and angular resolution DWI data were acquired preoperatively from 5 patients with Parkinson disease undergoing DBS. The authors compared the delineated hyperdirect pathways and associated STN target maps generated by 2 different tractography methods: a tensor-based deterministic method, typically available in clinical settings, and an advanced probabilistic method based on constrained spherical deconvolution. In addition, 10 highresolution data sets with the same scanning parameters were acquired from a healthy control participant to assess the robustness of the tractography results.

RESULTS Both tractography approaches identified connections between the ipsilateral motor cortex and the STN. However, the 2 methods provided substantially different target regions in the STN, with the target center of gravity differing by > 1.4 mm on average. The probabilistic method (based on constrained spherical deconvolution) plausibly reconstructed a continuous set of connections from the motor cortex, terminating in the dorsolateral region of the STN. In contrast, the tensor-based method reconstructed a comparatively sparser and more variable subset of connections. Furthermore, across the control scans, the probabilistic method identified considerably more consistent targeting regions within the STN compared with the deterministic tensor-based method, which demonstrated a 1.9–2.4 times higher variation.

CONCLUSIONS These data provide a strong impetus for the use of a robust probabilistic tractography framework based on constrained spherical deconvolution, or similar advanced DWI models, in clinical settings. The inherent limitations and demonstrated inaccuracy of the tensor-based method leave it questionable for use in high-precision stereotactic DBS surgery. The authors have also described a straightforward method for importing tractography-derived information into any clinical neuronavigation system, based on the generation of track-density images.

Simultaneous bilateral stereotactic procedure for deep brain stimulation implants

Simultaneous bilateral stereotactic procedure for deep brain stimulation implants

J Neurosurg 125:85–89, 2016

Currently, bilateral procedures involve 2 sequential implants in each of the hemispheres. The present report demonstrates the feasibility of simultaneous bilateral procedures during the implantation of deep brain stimulation (DBS) leads.

Methods Fifty-seven patients with movement disorders underwent bilateral DBS implantation in the same study period. The authors compared the time required for the surgical implantation of deep brain electrodes in 2 randomly assigned groups. One group of 28 patients underwent traditional sequential electrode implantation, and the other 29 patients underwent simultaneous bilateral implantation. Clinical outcomes of the patients with Parkinson’s disease (PD) who had undergone DBS implantation of the subthalamic nucleus using either of the 2 techniques were compared.

Results Overall, a reduction of 38.51% in total operating time for the simultaneous bilateral group (136.4 ± 20.93 minutes) as compared with that for the traditional consecutive approach (220.3 ± 27.58 minutes) was observed. Regarding clinical outcomes in the PD patients who underwent subthalamic nucleus DBS implantation, comparing the preoperative off-medication condition with the off-medication/on-stimulation condition 1 year after the surgery in both procedure groups, there was a mean 47.8% ± 9.5% improvement in the Unified Parkinson’s Disease Rating Scale Part III (UPDRS-III) score in the simultaneous group, while the sequential group experienced 47.5% ± 15.8% improvement (p = 0.96). Moreover, a marked reduction in the levodopa-equivalent dose from preoperatively to postoperatively was similar in these 2 groups. The simultaneous bilateral procedure presented major advantages over the traditional sequential approach, with a shorter total operating time.

Conclusions A simultaneous stereotactic approach significantly reduces the operation time in bilateral DBS procedures, resulting in decreased microrecording time, contributing to the optimization of functional stereotactic procedures.

Fully Automated Targeting Using Nonrigid Image Registration Matches Accuracy and Exceeds Precision of Best Manual Approaches to Subthalamic Deep Brain Stimulation Targeting in Parkinson Disease

DBS 2 leads metal head holder

Neurosurgery 76:756–765, 2015

Finding the optimal location for the implantation of the electrode in deep brain stimulation (DBS) surgery is crucial for maximizing the therapeutic benefit to the patient. Such targeting is challenging for several reasons, including anatomic variability between patients as well as the lack of consensus about the location of the optimal target.

OBJECTIVE: To compare the performance of popular manual targeting methods against a fully automatic nonrigid image registration-based approach.

METHODS: In 71 Parkinson disease subthalamic nucleus (STN)-DBS implantations, an experienced functional neurosurgeon selected the target manually using 3 different approaches: indirect targeting using standard stereotactic coordinates, direct targeting based on the patient magnetic resonance imaging, and indirect targeting relative to the red nucleus. Targets were also automatically predicted by using a leave-one-out approach to populate the CranialVault atlas with the use of nonrigid image registration. The different targeting methods were compared against the location of the final active contact, determined through iterative clinical programming in each individual patient.

RESULTS: Targeting by using standard stereotactic coordinates corresponding to the center of the motor territory of the STN had the largest targeting error (3.69 mm), followed by direct targeting (3.44 mm), average stereotactic coordinates of active contacts from this study (3.02 mm), red nucleus-based targeting (2.75 mm), and nonrigid image registration-based automatic predictions using the CranialVault atlas (2.70 mm). The CranialVault atlas method had statistically smaller variance than all manual approaches.

CONCLUSION: Fully automatic targeting based on nonrigid image registration with the use of the CranialVault atlas is as accurate and more precise than popular manual methods for STN-DBS.

Multitract Orthogonal Microelectrode Localization of the Subthalamic Nucleus

Multitract Orthogonal Microelectrode Localization of the Subthalamic Nucleus

Operative Neurosurgery 10:240–245, 2014

Microelectrode recording helps surgeons accurately localize boundaries of the subthalamic nucleus (STN) and surrounding structures in deep brain stimulation.

OBJECTIVE: To describe a novel adaptation of the Ben gun device to optimize efficient mapping.

METHODS: Patients who underwent STN deep brain stimulation over a 3-year period were reviewed. For the final year, the Ben gun was rotated 45 and the target was offset 1.4 mm lateral and anterior in the plane orthogonal to the intended trajectory to allow for simultaneous parallel tracks at target, 2.8 mm anterior (localizing the front of STN), and 2.8 mm lateral (identifying the internal capsule). Before this step, the initial pass consisted of 1 to 2 tracks with the frame center targeted to STN. The primary outcome measure was the number of passes required for accurate localization of the nucleus and boundaries.

RESULTS: Eighty-three electrodes were implanted in 45 patients (mean age, 62; range, 37-78 years), of which 29 electrodes were placed by the use of the new technique. One electrode (4%) required more than 1 pass using the new technique compared with 36 (67%) using the older technique (P , .01). The distance from original target to final electrode position increased from 0.67 6 0.13 mm to 1.06 6 0.15 mm (P , .05) with a greater tendency to move the final electrode position posteriorly. There was no statistically significant difference in benefit from neurostimulation.

CONCLUSION: This technique facilitates reliable localization of the STN with fewer passes, possibly decreasing the risks associated with more passes and longer duration of surgery.

Fiber tractography of basal ganglia and cerebellum in PD

Fiber tractography of basal ganglia and cerebellum in PD

J Neurosurg 120:988–996, 2014

Stimulation of white matter pathways near targeted structures may contribute to therapeutic effects of deep brain stimulation (DBS) for patients with Parkinson disease (PD). Two tracts linking the basal ganglia and cerebellum have been described in primates: the subthalamopontocerebellar tract (SPCT) and the dentatothalamic tract (DTT). The authors used fiber tractography to evaluate white matter tracts that connect the cerebellum to the region of the basal ganglia in patients with PD who were candidates for DBS.

Methods. Fourteen patients with advanced PD underwent 3-T MRI, including 30-directional diffusion-weighted imaging sequences. Diffusion tensor tractography was performed using 2 regions of interest: ipsilateral subthalamic and red nuclei, and contralateral cerebellar hemisphere. Nine patients underwent subthalamic DBS, and the course of each tract was observed relative to the location of the most effective stimulation contact and the volume of tissue activated.

Results. In all patients 2 distinct tracts were identified that corresponded closely to the described anatomical features of the SPCT and DTT, respectively. The mean overall distance from the active contact to the DTT was 2.18 ± 0.35 mm, and the mean proportional distance relative to the volume of tissue activated was 1.35 ± 0.48. There was a nonsignificant trend toward better postoperative tremor control in patients with electrodes closer to the DTT.

Conclusions. The SPCT and the DTT may be related to the expression of symptoms in PD, and this may have implications for DBS targeting. The use of tractography to identify the DTT might assist with DBS targeting in the future.

The Anatomical and Electrophysiological Subthalamic Nucleus Visualized by 3-T Magnetic Resonance Imaging

The Anatomical and Electrophysiological Subthalamic Nucleus Visualized by 3-T Magnetic Resonance Imaging

Neurosurgery 71:1089–1095, 2012

Accurate localization of the subthalamic nucleus (STN) is critical to the success of deep brain stimulation surgery for Parkinson disease. Recent developments in high-field-strength magnetic resonance imaging (MRI) have made it possible to visualize the STN in greater detail. However, the relationship of the MR-visualized STN to the anatomic, electrophysiological, or atlas-predicted STN remains controversial.

OBJECTIVE: To evaluate the size of the STN visualized on 3-T MRI compared with anatomic measurements in cadaver studies and to compare the predictions of 3-T MRI and those of the Schaltenbrand-Wahren (SW) atlas for intraoperative STN microelectrode recordings.

METHODS: We evaluated the STN by 3-T MRI and intraoperative microelectrode recordings in 20 Parkinson disease patients undergoing deep brain stimulation surgery. We compared our findings with anatomic cadaver studies and with the individually scaled SW atlas-based predictions for each patient.

RESULTS: The dimensions of the 3-T MR-visualized STN were very similar to those of the largest anatomic study (MRI length, width, and height: 9.8 6 1.6, 11.5 6 1.6, and 3.7 6 0.7 mm, respectively; n = 40; cadaver length, width, and height: 9.3 6 0.7, 10.6 6 0.9, and 3.1 6 0.5 mm, respectively; n = 100). The amount of STN traversed during intraoperative microelectrode recordings was better correlated to the 3-T MR-visualized STN than the SW atlas-predicted STN (R = 0.38 vs R = 20.17).

CONCLUSION: The STN as visualized on 3-T MRI corresponds well with cadaveric anatomic studies and intraoperative electrophysiology. STN visualization with 3-T MRI may be an improvement over SW atlas-based localization for STN deep brain stimulation surgery in Parkinson disease.

Unilateral Extradural Motor Cortex Stimulation Is Safe and Improves Parkinson Disease at 1 Year

Neurosurgery 71:815–825, 2012

The primary motor cortex, which is part of the corticobasal ganglia loops, may be an alternative option for the surgical treatment of Parkinson disease.

OBJECTIVE: To report on the 1-year safety and efficacy of unilateral extradural motor cortex stimulation in Parkinson disease.

METHODS: A quadripolar electrode strip was extradurally implanted over the motor cortex. Stimulation was continuously delivered through the electrode paddle contralateral to the most affected clinical side. Subjects were prospectively evaluated by the Unified Parkinson’s Disease Rating Scale (UPDRS) and the Parkinson’s Disease Quality of Life Questionnaire. In addition, an extensive cognitive and behavioral assessment and electroencephalogram recording were performed.

RESULTS: Nine patients were included in this study. No surgical complications or adverse events occurred. Moreover, no cognitive or behavioral changes were observed. Under the off-medication condition, the UPDRS III at baseline was decreased by 14.1%, 23.3%, 19.9%, and 13.2%, at 1, 3, 6, and 12 months, respectively. The motor effects were bilateral, appeared after 3 to 4 weeks of stimulation, and outlasted the stimulation itself for 3 to 4 weeks in 1 case of stimulator accidental switching off. The UPDRS IV was decreased by 40.8%, 42.1%, and 35.5% at 1, 3, and 12 months, respectively. The scores on the Parkinson’s Disease Quality of Life Questionnaire were increased at months 3, 6, and 12.

CONCLUSION: Extradural motor cortex stimulation is a safe procedure. After 12 months, the patients demonstrated a moderate improvement of motor symptoms (particularly axial symptoms) and quality of life.

Limbic and Motor Function Comparison of Deep Brain Stimulation of the Zona Incerta and Subthalamic Nucleus

Neurosurgery 70[ONS Suppl 1]:ons125–ons131, 2012 DOI: 10.1227/NEU.0b013e318232fdac

Psychiatric and neuropsychological side effects of subthalamic nucleus (STN) stimulation have been increasingly recognized. Most programming regimens focus on contacts 0 and 1, whereas contact 3, which often is located near or in the zona incerta (ZI), is usually not used. The question of whether ZI stimulation may limit limbic effects has not been answered.

OBJECTIVE: To examine the effects of short-term stimulation near or in the ZI (contact 3) compared with stimulation of the STN using standard trajectories and targeting as measured by limbic and motor functions.

METHODS: Motor and limbic functions of 11 patients with STN DBS were assessed with the Unified Parkinson Disease Rating Scale-3, structured gait video analysis, Visual Analog Scale mood scales, task testing of impulsivity, and facial recognition under routine STN programming and under stimulation in or near the ZI. Postoperative magnetic resonance imaging confirmed the location of contact 3 near or in the ZI.

RESULTS: Data analysis with repeated-measures analysis of variance revealed that motor scores remained stable with both stimulation settings, with specific improvements in finger taps (P = .02) and rapid alternating movements (P = .03) in ZI stimulation. Stimulation near or in the ZI led to a decrease in self- reported anxiety and depression (P = .03 for both) and an improvement in fear recognition (P = .02).

CONCLUSION: We provide preliminary evidence that stimulation in or near the ZI results in maintained motor function while improving self-reported depression and anxiety in patients with bilateral STN DBS. Stimulation in or near the ZI may provide a useful programming setting for patients prone to psychiatric side effects.

Fiducial Registration With Spoiled Gradient-Echo Magnetic Resonance Imaging Enhances the Accuracy of Subthalamic Nucleus Targeting

Neurosurgery 69:870–875, 2011 DOI: 10.1227/NEU.0b013e318222ae33

A variety of imaging strategies may be used to derive reliable stereotactic coordinates when performing deep brain stimulation lead implants. No single technique has yet proved optimal.

OBJECTIVE: To compare the relative accuracy of stereotactic coordinates for the subthalamic nucleus (STN) derived either from fast spin echo/inversion recovery (FSE/IR) magnetic resonance imaging MRI alone (group 1) or FSE/IR in conjunction with T1- weighted spoiled gradient-echo MRI (group 2).

METHODS: A retrospective analysis of 145 consecutive STN deep brain stimulation lead placements (group 1, n = 72; group 2, n = 73) was performed in 81 Parkinson disease patients by 1 surgical team. From the operative reports, we recorded the number of microelectrode recording trajectories required to localize the desired STN target and the span of STN traversed along the implantation trajectory. In addition, we calculated the 3-dimensional vector difference between the initial MRI-derived coordinates and the final physiologically refined coordinates.

RESULTS: The proportion of implants completed with just 1 microelectrode recording trajectory was greater (81% vs 58%; P < .001) and the 3-dimensional vector difference between the anatomically selected target and the microelectrode recording–refined target was smaller (0.6 ± 1.2 vs 0.9 ± 1.3; P = .04) in group 2 than in group 1. At the same time, the mean expanse of STN recorded along the implantation trajectory was 8% greater in group 2 (4.8 ± 0.6 vs 5.2 ± 0.6 mm; P < .001).

CONCLUSION: A combination of stereotactic FSE/IR and spoiled gradient-echo MRI yields more accurate coordinates for the STN than FSE/IR MRI alone.

Intraoperative magnetic resonance imaging findings during deep brain stimulation surgery

J Neurosurg 115:852–857, 2011.DOI: 10.3171/2011.5.JNS101457

Deep brain stimulation (DBS) is an established neurosurgical technique used to treat a variety of neurological disorders, including Parkinson disease, essential tremor, dystonia, epilepsy, depression, and obsessive-compulsive disorder. This study reports on the use of intraoperative MR imaging during DBS surgery to evaluate acute hemorrhage, intracranial air, brain shift, and accuracy of lead placement.

Methods. During a 46-month period, 143 patients underwent 152 DBS surgeries including 289 lead placements utilizing intraoperative 1.5-T MR imaging. Imaging was supervised by an MR imaging physicist to maintain the specific absorption rate below the required level of 0.1 W/kg and always included T1 magnetization-prepared rapid gradient echo and T2* gradient echo sequences with selected use of T2 fluid attenuated inversion recovery (FLAIR) and T2 fast spin echo (FSE). Retrospective review of the intraoperative MR imaging examinations was performed to quantify the amount of hemorrhage and the amount of air introduced during the DBS surgery.

Results. Intraoperative MR imaging revealed 5 subdural hematomas, 3 subarachnoid hemorrhages, and 1 intraparenchymal hemorrhage in 9 of the 143 patients. Only 1 patient experiencing a subarachnoid hemorrhage developed clinically apparent symptoms, which included transient severe headache and mild confusion. Brain shift due to intracranial air was identified in 144 separate instances.

Conclusions. Intraoperative MR imaging can be safely performed and may assist in demonstrating acute changes involving intracranial hemorrhage and air during DBS surgery. These findings are rarely clinically significant and typically resolve prior to follow-up imaging. Selective use of T2 FLAIR and T2 FSE imaging can confirm the presence of hemorrhage or air and preclude the need for CT examinations

Transgressing the Ventricular Wall During Subthalamic Deep Brain Stimulation Surgery for Parkinson Disease Increases the Risk of Adverse Neurological Sequelae

Neurosurgery 69:294–300, 2011 DOI: 10.1227/NEU.0b013e318214abda

Deep brain stimulation (DBS) at the subthalamic nucleus (STN) is an effective treatment for the motor manifestations of advanced medically refractory Parkinson disease. Because of the medial location of the target, surgical trajectories to the STN may violate the ipsilateral lateral ventricle.

OBJECTIVE: To determine whether violating the ventricle during STN DBS surgery is associated with postoperative confusion.

METHODS: A retrospective chart review of all STN implantation procedures for Parkinson disease performed by 1 surgeon between January 2005 and September 2008 was performed. Postoperative magnetic resonance imaging was performed in all cases, and each scan was reviewed for evidence of ventricular wall violation. All charts were reviewed for postoperative confusion and/or increased length of hospital stay.

RESULTS: A total of 145 leads were implanted in 81 patients over 102 admissions. Fortythree patients underwent contemporaneous bilateral lead implantation; 23 underwent unilateral implantation; and 18 underwent staged bilateral implantation. The cases of 8 patients were complicated by postoperative confusion and increased length of stay. Sixteen magnetic resonance imaging scans demonstrated evidence of ventricular wall violation including all 8 patients with postoperative confusion. The relative risk of having postoperative confusion after traversing the ventricle is 87 (P , .001).

CONCLUSION: Violating the ventricular system during STN DBS surgery correlated significantly with postoperative altered mental status and subsequent increased length of hospital stay. This finding may explain why cognitive complications are observed more frequently in Parkinson disease patients undergoing DBS at the STN compared with the internal globus pallidus.

High-Frequency Pallidal Stimulation for Camptocormia in Parkinson Disease: Case Report

Neurosurgery 68:E1501–E1505, 2011 DOI: 10.1227/NEU.0b013e318210c859

Camptocormia is characterized by abnormal flexion of the thoracolumbar spine that increases during upright posture and abates in the recumbent position and has been reported to occur in patients with Parkinson disease. Camptocormia causes significant spinal and abdominal pain, impairment of balance, and social stigma.

CLINICAL PRESENTATION: A 57-year-old woman with Parkinson disease developed severe camptocormia, which did not improve with trials of antiparkinsonian and muscle relaxant medications. The patient was successfully treated with bilateral globus pallidus interna deep brain stimulation surgery under general anesthesia. High-frequency neuromodulation afforded relief of camptocormia and improvement in Parkinson disease symptoms.

CONCLUSION: Camptocormia in Parkinson disease may represent a form of dystonia and can be treated effectively with chronic pallidal neuromodulation.

Direct visualization of deep brain stimulation targets in Parkinson disease with the use of 7-tesla magnetic resonance imaging

J Neurosurg 113:639–647, 2010.DOI: 10.3171/2010.3.JNS091385

A challenge associated with deep brain stimulation (DBS) in treating advanced Parkinson disease (PD) is the direct visualization of brain nuclei, which often involves indirect approximations of stereotactic targets. In the present study, the authors compared T2*-weighted images obtained using 7-T MR imaging with those obtained using 1.5- and 3-T MR imaging to ascertain whether 7-T imaging enables better visualization of targets for DBS in PD.

Methods. The authors compared 1.5-, 3-, and 7-T MR images obtained in 11 healthy volunteers and 1 patient with PD.

Results. With 7-T imaging, distinct images of the brain were obtained, including the subthalamic nucleus (STN) and internal globus pallidus (GPi). Compared with the 1.5- and 3-T MR images of the STN and GPi, the 7-T MR images showed marked improvements in spatial resolution, tissue contrast, and signal-to-noise ratio.

Conclusions. Data in this study reveal the superiority of 7-T MR imaging for visualizing structures targeted for DBS in the management of PD. This finding suggests that by enabling the direct visualization of neural structures of interest, 7-T MR imaging could be a valuable aid in neurosurgical procedures.

Effect of subthalamic deep brain stimulation on postural abnormality in Parkinson disease

J Neurosurg 112:1283–1288, 2010.DOI: 10.3171/2009.10.JNS09917

Parkinson disease (PD) is often accompanied by various postural abnormalities such as camptocormia (bent spine) or Pisa syndrome (lateral flexion). The authors studied the effect of subthalamic nucleus deep brain stimulation (STN DBS) on postural abnormality in patients with PD.

Methods. The authors retrospectively reviewed the clinical course of 18 patients who suffered from significant postural abnormality and underwent bilateral STN DBS. Patients whose preoperative posture score (Unified Parkinson’s Disease Rating Scale III, item 28) was 2 or more in the “medication-on” state were enrolled in this study. Eight patients were considered to have camptocormia, and 10 patients were considered to have so-called Pisa syndrome. Nine patients showed apparent thoracolumbar spinal deformity on radiography. Most patients had significant motor fluctuations from levodopa.

Results. In 13 patients with moderate postural abnormality (score of 2 on item 28), 9 patients improved soon after surgery, but 1 patient relapsed. Two patients improved gradually over a long period after surgery, whereas 2 patients did not improve at all. In 5 patients with severe postural abnormality (score of 3 or 4 on item 28), 2 patients improved slightly in the long-term follow-up period after surgery, but 3 patients did not improve at all.

Conclusions. Postural abnormality in patients with PD could be ameliorated by STN DBS, and therefore surgery should be considered before irreversible spinal deformity develops

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