Neurosurgery Blog


Daily bibliographic review of the Neurosurgery Department. La Fe University Hospital. Valencia, Spain

Exploring the brain through posterior hypothalamus surgery for aggressive behavior

Neurosurg Focus 43 (3):E14, 2017

Neurological surgery offers an opportunity to study brain functions, through either resection or implanted neuromodulation devices. Pathological aggressive behavior in patients with intellectual disability is a frequent condition that is difficult to treat using either supportive care or pharmacological therapy.

The bulk of the laboratory studies performed throughout the 19th century enabled the formulation of hypotheses on brain circuits involved in the generation of emotions.

Aggressive behavior was also studied extensively. Lesional radiofrequency surgery of the posterior hypothalamus, which peaked in the 1970s, was shown to be an effective therapy in many reported series. As with other surgical procedures for the treatment of psychiatric disorders, however, this therapy was abandoned for many reasons, including the risk of its misuse.

Deep brain stimulation (DBS) offers the possibility of treating neurological and psychoaffective disorders through relatively reversible and adaptable therapy. Deep brain stimulation of the posterior hypothalamus was proposed and performed successfully in 2005 as a treatment for aggressive behavior. Other groups reported positive outcomes using target and parameter settings similar to those of the original study. Both the lesional and DBS approaches enabled researchers to explore the role of the posterior hypothalamus (or posterior hypothalamic area) in the autonomic and emotional systems.


Complications in awake versus asleep DBS

J Neurosurg 127:360–369, 2017

As the number of deep brain stimulation (DBS) procedures performed under general anesthesia (“asleep” DBS) increases, it is more important to assess the rates of adverse events, inpatient lengths of stay (LOS), and 30-day readmission rates in patients undergoing these procedures compared with those in patients undergoing traditional “awake” DBS without general anesthesia.

METHODS All patients in an institutional database who had undergone awake or asleep DBS procedures performed by a single surgeon between August 2011 and August 2014 were reviewed. Adverse events, inpatient LOS, and 30-day readmissions were analyzed.

RESULTS A total of 490 electrodes were placed in 284 patients, of whom 126 (44.4%) underwent awake surgery and 158 (55.6%) underwent asleep surgery. The most frequent overall complication for the cohort was postoperative mental status change (13 patients [4.6%]), followed by hemorrhage (4 patients [1.4%]), seizure (4 patients [1.4%]), and hardwarerelated infection (3 patients [1.1%]). Mean LOS for all 284 patients was 1.19 ± 1.29 days (awake: 1.06 ± 0.46 days; asleep: 1.30 ± 1.67 days; p = 0.08). Overall, the 30-day readmission rate was 1.4% (1 awake patient, 3 asleep patients). There were no significant differences in complications, LOS, and 30-day readmissions between awake and asleep groups.

CONCLUSIONS Both awake and asleep DBS can be performed safely with low complication rates. The authors found no significant differences between the 2 procedure groups in adverse events, inpatient LOS, and 30-day readmission rates.

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.


Underutilization of deep brain stimulation for Parkinson’s disease?

Acta Neurochir (2017) 159:771–778

Only 10% of the up to 15% of patients with advanced Parkinson’s disease (PD) eligible for deep brain stimulation (DBS) are referred to specialized centers. This survey evaluated the reasons for the reluctance of patients and referring physicians regarding DBS.

Methods: Two different questionnaires containing multiple choice and open verbalized questions were developed, one for neurologists and one for patients with PD. The first questionnaire was sent to 87 neurologists in private practice in the catchment area of the authors’ medical center, the second to patient support groups in the same region with the help of the German Parkinson Association.

Results: Of the addressed neurologists, 56.3% completed the questionnaire; 61.2% of themestimated the risk of intracerebral hemorrhage as the most severe complication at 4.3% on average; 30.6% were concerned about patients developing mood changes or depression after DBS. Only 16.3% felt unable to care for patients after DBS; 61.2% already had personal experience with patients after DBS and reported good clinical outcome in 90.0% of patients. Although 87.8% claimed to know the specific criteria for DBS, only 40.8% could actively describe them. Only 14.0% could state each of the three main criteria. Of the 46 patients, 88.1% completing the questionnaire had obtained information on DBS from regional patient organizations and 54.8% also from a physician; 44.7% assumed the risk of severe complications to be ≥5.0%. Not being satisfied with their medical treatment was reported by 22.2%, of whom more than 70% considered DBS a further treatment option.

Conclusions The latter numbers indicate that treating neurologists tend to overestimate the reluctance of their patients to undergo DBS. Therefore, education of patients and neurologists should be improved and give more realistic figures on the actual outcomes and frequencies of possible complications.

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.

Combined thalamic and subthalamic deep brain stimulation for tremor-dominant Parkinson’s disease

Acta Neurochir (2017) 159:265–269

Deep brain stimulation (DBS) in the thalamic ventral intermediate (Vim) or the subthalamic nucleus (STN) reportedly improves medication-refractory Parkinson’s disease (PD) tremor. However, little is known about the potential synergic effects of combined Vim and STN DBS.

We describe a 79-year-old man with medication-refractory tremor-dominant PD. Bilateral Vim DBS electrode implantation produced insufficient improvement. Therefore, the patient underwent additional unilateral left-sided STN DBS. Whereas Vim or STN stimulation alone led to partial improvement, persisting tremor resolution occurred after simultaneous stimulation.

The combination of both targets may have a synergic effect and is an alternative option in suitable cases.

Endoventricular Deep Brain Stimulation of the Third Ventricle: Proof of Concept and Application to Cluster Headache

Neurosurgery 79:806–815, 2016

The third ventricle (3rd V) is surrounded by centers related to satiety, homeostasis, hormones, sleep, memory, and pain. Stimulation of the wall of the 3rd V could be useful to treat disorders related to dysfunction of the hypothalamus.

OBJECTIVE: To assess safety and efficacy of endoventricular electrical stimulation of the hypothalamus using a floating deep brain stimulation (DBS) lead laid on the floor of the 3rd V to treat refractory cluster headaches (CH).

METHODS: Seven patients, aged 24 to 60 years, experiencing chronic CH (mean chronic duration 5.8 6 2.5 years) were enrolled in this pilot, prospective, open study assessing the safety and potential efficacy of chronic DBS of the 3rd V. Number of attacks was collected during baseline and was compared with those occurring at 3, 6, and 12 months postoperation. Any side effects that occurred during or after surgery were reported. Effect on mood was assessed using the Hospital Anxiety and Depression scale during baseline and at 6 and 12 months postoperation.

RESULTS: Insertion of the lead into the posterior 3rd V and chronic stimulation was feasible and safe in all patients. The voltage ranged from 0.9 to 2.3 volts. The most common side effect was transient trembling vision during stimulation. At 12 months, 3 of 7 patients were pain free, 2 had 90% improvement, 1 of 7 had 75% improvement, and 1 of 7 was not significantly improved.

CONCLUSION: This proof of concept demonstrates the feasibility, safety, and potential efficacy of 3rd V DBS using an endoventricular road that could be applied to treat various diseases involving hypothalamic areas. Read the rest of this entry »

STN DBS for Parkinson’s disease: results from a series of ten consecutive patients implanted under general anaesthesia with intraoperative use of 3D fluoroscopy to control lead placement

Artis Zeego

Acta Neurochir (2016) 158:1783–1788

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a recognised treatment for advanced Parkinson’s disease (PD). We present our results of 10 consecutive patients implanted under general anaesthesia (GA) using intraoperative robotic three-dimensional (3D) fluoroscopy (Artis Zeego; Siemens, Erlangen, Germany).

Method Ten patients (nine men, one woman) with a mean age of 57.6 (range, 41–67) years underwent surgery between October 2013 and January 2015. The mean duration of PD was 9.2 [1–10] year. The procedure was performed under GA: placement of the stereotactic frame, implantation of the electrodes (Lead 3389; Medtronic, Minnesota,MN, USA) and 3D intraoperative fluoroscopic control (Artis Zeego) with image fusion with the preoperative MRI scans. All patients were evaluated preoperatively and 6 months postoperatively.

Results The mean operative time was 240.1 (185–325) min. Themean Unified Parkinson’s Disease Rating Scale (UPDRS) II OFF medication decreased from 23.9 preoperatively to 15.7 postoperatively. The mean OFF medication UPDRS III decreased from 41 to 11.6 and the UPDRS IV decreased from 10.6 to 7. The mean preoperative and postoperative L-Dopa doses were 1,178.5 and 696.5 mg, respectively. Two complications were recorded: one episode of transient confusion (24 h) and one internal pulse generator (IPG) infection.

Conclusions With improvement in preoperative magnetic resonance imaging (MRI) and the ability to control the position of the leads intraoperatively using Artis Zeego, we now perform this procedure under GA. Our results are comparable to others reported. The significant decrease in the duration of surgery could be associated with a reduced rate of complications (infection, loss of patient collaboration). However, this observation needs to be confirmed.

Interventional magnetic resonance imaging‑guided subthalamic nucleus deep brain stimulation for Parkinson’s disease: Patient selection


Surg Neurol Int 02-Aug-2016;7:

Interventional magnetic resonance imaging (iMRI) guided deep brain stimulation (DBS) for Parkinson’s disease (PD) has been shown to be effective. The costs of a dedicated intraoperative MRI may be prohibitive. The procedure can also be performed in a diagnostic scanner, however this presents challenges for utilization of time when the scanner is used both as a diagnostic and an interventional unit. This report outlines our novel methodology for patient selection for implantation in a diagnostic MR scanner, as an attempt to streamline the use of resources. A retrospective review of our outcomes is also presented.

Methods: DBS candidacy evaluation included a PD questionnaire‑39. Anxiety, age, difficulties in communication and body habitus were factors that were assessed in selecting patients for this technique. Eleven patients underwent iMRI‑guided DBS implantation in the subthalamic nucleus. All patients were implanted bilaterally. Unified PD rating scale (UPDRS) part III and L‑dopa dose were compared pre‑ and post‑stimulation. A cohort of 11 DBS patients not selected for iMRI‑guided DBS were also reported for comparison.

Results: For the iMRI‑guided patients, mean “Off” UPDRS III score was 47.6 (standard deviation [SD] 8.26). Postoperative “On” medication, “On” stimulation UPDRS III was 13.6 (SD 5.23). Mean preoperative L‑dopa dose was 1060 mg (SD 474.3) and mean postoperative L‑dopa dose was 320 (SD 298.3).

Conclusion: iMRI‑guided DBS is a newly emerging technique for surgical treatment of patients with PD. We present a novel scoring system for patient selection assessing anxiety, age, ability to communicate, and body habitus to identify patients who will be benefited most from this technique.

Improved Function After Deep Brain Stimulation for Chronic, Severe Traumatic Brain Injury

Improved Function After Deep Brain Stimulation for Chronic, Severe Traumatic Brain Injury

Neurosurgery 79:204–211, 2016

Severe traumatic brain injury (TBI) damages the frontal lobes and connecting networks, which impairs executive functions, including the ability to selfregulate. Despite significant disabling effects, there are few treatment options in the chronic phase after injury.

OBJECTIVE: To investigate the safety and potential effectiveness of deep brain stimulation (DBS) for individuals with chronic, disabling TBI and problems of behavioral and emotional self-regulation.

METHODS: This study was an open-label, prospective design with serial assessments of behavioral outcomes and positron emission tomography 2 years after DBS implantation. Four participants 6 to 21 years after severe TBIs from automobile crashes were included. Although alert and volitional, all experienced significant executive impairments, including either impulsivity or reduced initiation. DBS implants were placed bilaterally in the nucleus accumbens and anterior limb of the internal capsule to modulate the prefrontal cortex.

RESULTS: The procedure was safe, and all participants had improved functional outcomes. Two years after implantation, 3 met a priori criteria for improvement on the Mayo-Portland Adaptability Inventory-4. Improvement was due largely to better emotional adjustment, although 1 participant showed marked increases in multiple domains. Significant improvement in a composite score of functional capacity indicated improved independence in self-care and activities of daily living. The pattern of change in cognition corresponded with changes in activation of the prefrontal cortex observed in serial scanning.

CONCLUSION: This first study of DBS to this target for severe TBI supports its safety and suggests potential effectiveness to improve function years after injury. The primary impact was on behavioral and emotional adjustment, which in turn improved functional independence.

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.

Bilateral deep brain stimulation of the fornix for Alzheimer’s disease

Bilateral deep brain stimulation of the fornix for Alzheimer’s disease

J Neurosurg 125:75–84, 2016

This report describes the stereotactic technique, hospitalization, and 90-day perioperative safety of bilateral deep brain stimulation (DBS) of the fornix in patients who underwent DBS for the treatment of mild, probable Alzheimer’s disease (AD).

Methods The ADvance Trial is a multicenter, 12-month, double-blind, randomized, controlled feasibility study being conducted to evaluate the safety, efficacy, and tolerability of DBS of the fornix in patients with mild, probable AD. Intraoperative and perioperative data were collected prospectively. All patients underwent postoperative MRI. Stereotactic analyses were performed in a blinded fashion by a single surgeon. Adverse events (AEs) were reported to an independent clinical events committee and adjudicated to determine the relationship between the AE and the study procedure.

Results Between June 6, 2012, and April 28, 2014, a total of 42 patients with mild, probable AD were treated with bilateral fornix DBS (mean age 68.2 ± 7.8 years; range 48.0–79.7 years; 23 men and 19 women). The mean planned target coordinates were x = 5.2 ± 1.0 mm (range 3.0–7.9 mm), y = 9.6 ± 0.9 mm (range 8.0–11.6 mm), z = -7.5 ± 1.2 mm (range -5.4 to -10.0 mm), and the mean postoperative stereotactic radial error on MRI was 1.5 ± 1.0 mm (range 0.2–4.0 mm). The mean length of hospitalization was 1.4 ± 0.8 days. Twenty-six (61.9%) patients experienced 64 AEs related to the study procedure, of which 7 were serious AEs experienced by 5 patients (11.9%). Four (9.5%) patients required return to surgery: 2 patients for explantation due to infection, 1 patient for lead repositioning, and 1 patient for chronic subdural hematoma. No patients experienced neurological deficits as a result of the study, and no deaths were reported.

Conclusions Accurate targeting of DBS to the fornix without direct injury to it is feasible across surgeons and treatment centers. At 90 days after surgery, bilateral fornix DBS was well tolerated by patients with mild, probable AD.

Anterior Nucleus Deep Brain Stimulation for Refractory Epilepsy

Anterior Nucleus Deep Brain Stimulation for Refractory Epilepsy

Neurosurgery 78:802–811, 2016

Anterior nucleus (AN) deep brain stimulation (DBS) is a palliative treatment for medically refractory epilepsy. The long-term efficacy and the optimal target localization for AN DBS are not well understood.

OBJECTIVE: To analyze the long-term efficacy of AN DBS and its predictors.

METHODS: We performed a retrospective review of 16 patients who underwent AN DBS. We selected only patients with reliable seizure frequency data and at least a 1-year follow-up. We studied the duration of the seizure reduction after DBS insertion and before stimulation (the insertional effect) and its association with long-term outcome. We modeled the volume of activation using the active contacts, stimulation parameters, and postoperative imaging. The overlap of this volume was plotted in Montreal Neurological Institute 152 space in 7 patients with significant clinical efficacy.

RESULTS: Nine patients reported a decrease in seizure frequency immediately after electrode insertion (insertional or microthalamotomy effect). The duration of insertional effect varied from 2 to 4 months. However, 1 patient had a long-term insertional effect of 36 months. Altogether, 11 patients reported .50% decrease in seizure frequency with long-term stimulation. The most common pattern of seizure control was immediate and sustained stimulation benefit (n = 8). In patients with long-term stimulation benefit, the efficacious target was localized in the anteroventral AN in close proximity to the mammillothalamic tract.

CONCLUSION: AN DBS is efficacious in the control of seizure frequency in selected patients. An insertional effect is commonly observed (56%). The most efficacious site of stimulation appears to be the anteroventral AN.

Cost analysis of awake versus asleep deep brain stimulation


J Neurosurg 124:1517–1523, 2016

The objective of this study was to compare the cost of deep brain stimulation (DBS) performed awake versus asleep at a single US academic health center and to compare costs across the University HealthSystem Consortium (UHC) Clinical Database.

Methods Inpatient and outpatient demographic and hospital financial data for patients receiving a neurostimulator lead implant (from the first quarter of 2009 to the second quarter of 2014) were collected and analyzed. Inpatient charges included those associated with International Classification of Diseases, Ninth Revision (ICD-9) procedure code 0293 (implantation or replacement of intracranial neurostimulator lead). Outpatient charges included all preoperative charges ≤ 30 days prior to implant and all postoperative charges ≤ 30 days after implant. The cost of care based on reported charges and a cost-to-charge ratio was estimated. The UHC database was queried (January 2011 to March 2014) with the same ICD-9 code. Procedure cost data across like hospitals (27 UHC hospitals) conducting similar DBS procedures were compared.

Results Two hundred eleven DBS procedures (53 awake and 158 asleep) were performed at a single US academic health center during the study period. The average patient age (± SD) was 65 ± 9 years old and 39% of patients were female. The most common primary diagnosis was Parkinson’s disease (61.1%) followed by essential and other forms of tremor (36%). Overall average DBS procedure cost was $39,152 ± $5340. Asleep DBS cost $38,850 ± $4830, which was not significantly different than the awake DBS cost of $40,052 ± $6604. The standard deviation for asleep DBS was significantly lower (p ≤ 0.05). In 2013, the median cost for a neurostimulator implant lead was $34,052 at UHC-affiliated hospitals that performed at least 5 procedures a year. At Oregon Health & Science University, the median cost was $17,150 and the observed single academic health center cost for a neurostimulator lead implant was less than the expected cost (ratio 0.97).

Conclusions In this single academic medical center cost analysis, DBS performed asleep was associated with a lower cost variation relative to the awake procedure. Furthermore, costs compared favorably to UHC-affiliated hospitals. While asleep DBS is not yet standard practice, this center exclusively performs asleep DBS at a lower cost than comparable institutions.


Neurosurgery for schizophrenia

Neurosurgery for schizophrenia

J Neurosurg 124:917–928, 2016

The main objectives of this review were to provide an update on the progress made in understanding specific circuit abnormalities leading to psychotic symptoms in schizophrenia and to propose rational targets for therapeutic deep brain stimulation (DBS).

Refractory schizophrenia remains a major unsolved clinical problem, with 10%–30% of patients not responding to standard treatment options. Progress made over the last decade was analyzed through reviewing structural and functional neuroimaging studies in humans, along with studies of animal models of schizophrenia. The authors reviewed theories implicating dysfunction in dopaminergic and glutamatergic signaling in the pathophysiology of the disorder, paying particular attention to neurosurgically relevant nodes in the circuit. In this context, the authors focused on an important pathological circuit involving the associative striatum, anterior hippocampus, and ventral striatum, and discuss the possibility of targeting these nodes for therapeutic neuromodulation with DBS. Finally, the authors examined ethical considerations in the treatment of these vulnerable patients.

The functional anatomy of neural circuits relevant to schizophrenia remains of great interest to neurosurgeons and psychiatrists and lends itself to the development of specific targets for neuromodulation. Ongoing progress in the understanding of these structures will be critical to the development of potential neurosurgical treatments of schizophrenia.

Parkinson’s disease outcomes after intraoperative CT-guided “asleep” deep brain stimulation in the globus pallidus internus

Parkinson’s disease outcomes after intraoperative CT-guided “asleep” deep brain stimulation in the globus pallidus internus

J Neurosurg 124:902–907, 2016

Recent studies show that deep brain stimulation can be performed safely and accurately without microelectrode recording or test stimulation but with the patient under general anesthesia. The procedure couples techniques for direct anatomical targeting on MRI with intraoperative imaging to verify stereotactic accuracy. However, few authors have examined the clinical outcomes of Parkinson’s disease (PD) patients after this procedure. The purpose of this study was to evaluate PD outcomes following “asleep” deep brain stimulation in the globus pallidus internus (GPi).

Methods The authors prospectively examined all consecutive patients with advanced PD who underwent bilateral GPi electrode placement while under general anesthesia. Intraoperative CT was used to assess lead placement accuracy. The primary outcome measure was the change in the off-medication Unified Parkinson’s Disease Rating Scale motor score 6 months after surgery. Secondary outcomes included effects on the 39-Item Parkinson’s Disease Questionnaire (PDQ-39) scores, on-medication motor scores, and levodopa equivalent daily dose. Lead locations, active contact sites, stimulation parameters, and adverse events were documented.

Results Thirty-five patients (24 males, 11 females) had a mean age of 61 years at lead implantation. The mean radial error off plan was 0.8 mm. Mean coordinates for the active contact were 21.4 mm lateral, 4.7 mm anterior, and 0.4 mm superior to the midcommissural point. The mean off-medication motor score improved from 48.4 at baseline to 28.9 (40.3% improvement) at 6 months (p < 0.001). The PDQ-39 scores improved (50.3 vs 42.0; p = 0.03), and the levodopa equivalent daily dose was reduced (1207 vs 1035 mg; p = 0.004). There were no significant adverse events.

Conclusions Globus pallidus internus leads placed with the patient under general anesthesia by using direct anatomical targeting resulted in significantly improved outcomes as measured by the improvement in the off-medication motor score at 6 months after surgery.

Intraoperative MRI and DBS for Parkinson disease


J Neurosurg 124:62–69, 2016

The degree of clinical improvement achieved by deep brain stimulation (DBS) is largely dependent on the accuracy of lead placement. This study reports on the evaluation of intraoperative MRI (iMRI) for adjusting deviated electrodes to the accurate anatomical position during DBS surgery and acute intracranial changes.

MethodsTwo hundred and six DBS electrodes were implanted in the subthalamic nucleus (STN) in 110 patients with Parkinson disease. All patients underwent iMRI after implantation to define the accuracy of lead placement. Fifty-six DBS electrode positions in 35 patients deviated from the center of the STN, according to the result of the initial postplacement iMRI scans. Thus, we adjusted the electrode positions for placement in the center of the STN and verified this by means of second or third iMRI scans. Recording was performed in adjusted parameters in the x-, y-, and z-axes.

ResultsFifty-six (27%) of 206 DBS electrodes were adjusted as guided by iMRI. Electrode position was adjusted on the basis of iMRI 62 times. The sum of target coordinate adjustment was -0.5 mm in the x-axis, -4 mm in the y-axis, and 15.5 mm in the z-axis; the total of distance adjustment was 74.5 mm in the x-axis, 88 mm in the y-axis, and 42.5 mm in the z-axis. After adjustment with the help of iMRI, all electrodes were located in the center of the STN. Intraoperative MRI revealed 2 intraparenchymal hemorrhages in 2 patients, brain shift in all patients, and leads penetrating the lateral ventricle in 3 patients.

ConclusionsThe iMRI technique can guide surgeons as they adjust deviated electrodes to improve the accuracy of implanting the electrodes into the correct anatomical position. The iMRI technique can also immediately demonstrate acute changes such as hemorrhage and brain shift during DBS surgery.

Deep Brain Stimulation in Gilles de la Tourette Syndrome

Deep Brain Stimulation in Gilles de la Tourette Syndrome

Neurosurgery 78:91–100, 2016

Gilles de la Tourette syndrome (GTS) is a severe neuropsychiatric disorder with childhood onset, characterized by disabling motor and vocal tics lasting for more than 1 year and associated with a wide range of psychiatric comorbidities. Pharmacological treatment is indicated for moderate to severe GTS patients. However, when GTS is refractory to conventional medical and behavioral treatments, deep brain stimulation (DBS) can be considered as a last resort therapeutic avenue.

OBJECTIVE: To evaluate the efficacy of DBS and its comorbidities in the largest pool of GTS patients to date.

METHODS: Our cohort study was based on 48 patients’ refractory to conventional treatment who underwent DBS for GTS at Galeazzi Institute, Milan, Italy. An exhaustive preoperative and a follow-up battery of tests was performed including the Yale Global Tic Severity Rating Scale, the Yale-Brown Obsessive Compulsive Scale, the Beck Depression Inventory, the State Trait Anxiety Inventory, and the Subjective Social Impairment on a 10-point Visual Analogue Scale tests.

RESULTS: Eleven patients in whom the device was removed for inflammatory complications or for poor compliance were excluded from final analysis. Twenty-seven of the remaining 37 patients had a Yale Global Tic Severity Rating Scale score at the last follow-up that was less than 35. Of the 37 patients, in 29 cases (78%) a reduction of more than 50% of the Yale Global Tic Severity Rating Scale score was observed.

CONCLUSION: The clinical efficacy of DBS in GTS is promising. Although DBS is associated with risks, as is any surgical intervention, DBS should be considered as a last resort therapeutic option in carefully selected GTS patients.

Deep Brain Stimulation of Heschl Gyrus


Neurosurgery 77:940–947, 2015

Tinnitus is a source of considerable morbidity, and neuromodulation has been shown to be a potential treatment option. However, the location of the primary auditory cortex within Heschl gyrus in the temporal operculum presents challenges for targeting and electrode implantation.

OBJECTIVE: To determine whether anatomic targeting with intraoperative verification using evoked potentials can be used to implant electrodes directly into the Heschl gyrus (HG).

METHODS: Nine patients undergoing stereo-electroencephalogram evaluation for epilepsy were enrolled. HG was directly targeted on volumetric magnetic resonance imaging, and framed stereotaxy was used to implant an electrode parallel to the axis of the gyrus by using an oblique anterolateral-posteromedial trajectory. Intraoperative evoked potentials from auditory stimuli were recorded from multiple electrode contacts. Postoperatively, stimulation of each electrode was performed and participants were asked to describe the percept. Audiometric analysis was performed for 2 participants during subthreshold stimulation.

RESULTS: Sounds presented to the contralateral and ipsilateral ears produced evoked potentials in HG electrodes in all participants intraoperatively. Stimulation produced a reproducible sensation of sound in all participants with perceived volume proportional to amplitude. Four participants reported distinct sounds when different electrodes were stimulated, with more medial contacts producing tones perceived as higher in pitch. Stimulation was not associated with adverse audiometric effects. There were no complications of electrode implantation.

CONCLUSION: Direct anatomic targeting with physiological verification can be used to implant electrodes directly into primary auditory cortex. If deep brain stimulation proves effective for intractable tinnitus, this technique may be useful to assist with electrode implantation.

Deep brain stimulation of the subthalamic nucleus: histological verification and 9.4-T MRI correlation

Deep brain stimulation of the subthalamic nucleus- histological verification and 9

Acta Neurochir (2015) 157:2143–2147

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) using an MRI-guided and MRI-verified technique without microelectrode recording is an effective and safe surgical treatment for patients with Parkinson’s disease (PD).

Objectives To assess the anatomical accuracy of lead placement after MRI-guided, MRI-verified STN DBS using postmortem histology and high-field MRI at 9.4 T.

Methods We conducted post-mortem analysis of a patient’s brain who had had MRI-guided, MRI-verified STN DBS for PD, using 9.4-TMRI and histology. After death, the brain was retrieved and a block including the electrode tracks down to the mesencephalon was examined with high-field MRI at 9.4 T and histological analysis.

Results High-field MRI images and corresponding histological examination showed that each electrode track ended within the intended target area, and that DBS did not cause significant neuroparenchymal tissue damage.

Conclusions This study supports the anatomical accuracy of the MRI-guided and MRI-verified method of STN DBS.

Neurosurgery Department. “La Fe” University Hospital. Valencia, Spain


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