Outcome of stereo-electroencephalography with single-unit recording in drug-refractory epilepsy.

OBJECTIVE: The aim of this study was to evaluate the utility and safety of "hybrid" stereo-electroencephalography (SEEG) in guiding epilepsy surgery and in providing information at single-neuron levels (i.e., single-unit recording) to further the understanding of the mechanisms of epilepsy and the neurocognitive processes unique to humans. METHODS: The authors evaluated 218 consecutive patients undergoing SEEG procedures from 1993 through 2018 at a single academic medical center to assess the utility and safety of this technique in both guiding epilepsy surgery and providing single-unit recordings. The hybrid electrodes used in this study contained macrocontacts and microwires to simultaneously record intracranial EEG and single-unit activity (hybrid SEEG). The outcomes of SEEG-guided surgical interventions were examined, as well as the yield and scientific utility of single-unit recordings in 213 patients who participated in the research involving single-unit recordings. RESULTS: All patients underwent SEEG implantation by a single surgeon and subsequent video-EEG monitoring (mean of 10.2 electrodes per patient and 12.0 monitored days). Epilepsy networks were localized in 191 (87.6%) patients. Two clinically significant procedural complications (one hemorrhage and one infection) were noted. Of 130 patients who underwent subsequent focal epilepsy surgery with a minimum 12-month follow-up, 102 (78.5%) underwent resective surgery and 28 (21.5%) underwent closed-loop responsive neurostimulation (RNS) with or without resection. Seizure freedom was achieved in 65 (63.7%) patients in the resective group. In the RNS group, 21 (75.0%) patients achieved 50% or greater seizure reduction. When the initial period of 1993 through 2013 before responsive neurostimulator implantation in 2014 was compared with the subsequent period of 2014 through 2018, the proportion of SEEG patients undergoing focal epilepsy surgery grew from 57.9% to 79.7% due to the advent of RNS, despite a decline in focal resective surgery from 55.3% to 35.6%. A total of 18,680 microwires were implanted in 213 patients, resulting in numerous significant scientific findings. Recent recordings from 35 patients showed a yield of 1813 neurons, with a mean yield of 51.8 neurons per patient. CONCLUSIONS: Hybrid SEEG enables safe and effective localization of epileptogenic zones to guide epilepsy surgery and provides unique scientific opportunities to investigate neurons from various brain regions in conscious patients. This technique will be increasingly utilized due to the advent of RNS and may prove a useful approach to probe neuronal networks in other brain disorders.

Novel tonometer device distinguishes brain stiffness in epilepsy surgery.

Complete surgical resection of abnormal brain tissue is the most important predictor of seizure freedom following surgery for cortical dysplasia. While lesional tissue is often visually indiscernible from normal brain, anecdotally, it is subjectively stiffer. We report the first experience of the use of a digital tonometer to understand the biomechanical properties of epilepsy tissue and to guide the conduct of epilepsy surgery. Consecutive epilepsy surgery patients (n = 24) from UCLA Mattel Children's Hospital were recruited to undergo intraoperative brain tonometry at the time of open craniotomy for epilepsy surgery. Brain stiffness measurements were corrected with abnormalities on neuroimaging and histopathology using mixed-effects multivariable linear regression. We collected 249 measurements across 30 operations involving 24 patients through the pediatric epilepsy surgery program at UCLA Mattel Children's Hospital. On multivariable mixed-effects regression, brain stiffness was significantly associated with the presence of MRI lesion (ß = 32.3, 95%CI 16.3-48.2; p < 0.001), severity of cortical disorganization (ß = 19.8, 95%CI 9.4-30.2; p = 0.001), and recent subdural grid implantation (ß = 42.8, 95%CI 11.8-73.8; p = 0.009). Brain tonometry offers the potential of real-time intraoperative feedback to identify abnormal brain tissue with millimeter spatial resolution. We present the first experience with this novel intraoperative tool for the conduct of epilepsy surgery. A carefully designed prospective study is required to elucidate whether the clinical application of brain tonometry during resective procedures could guide the area of resection and improve seizure outcomes.

Theta-burst microstimulation in the human entorhinal area improves memory specificity.

The hippocampus is critical for episodic memory, and synaptic changes induced by long-term potentiation (LTP) are thought to underlie memory formation. In rodents, hippocampal LTP may be induced through electrical stimulation of the perforant path. To test whether similar techniques could improve episodic memory in humans, we implemented a microstimulation technique that allowed delivery of low-current electrical stimulation via 100 µm-diameter microelectrodes. As thirteen neurosurgical patients performed a person recognition task, microstimulation was applied in a theta-burst pattern, shown to optimally induce LTP. Microstimulation in the right entorhinal area during learning significantly improved subsequent memory specificity for novel portraits; participants were able both to recognize previously-viewed photos and reject similar lures. These results suggest that microstimulation with physiologic level currents-a radical departure from commonly used deep brain stimulation protocols-is sufficient to modulate human behavior and provides an avenue for refined interrogation of the circuits involved in human memory.

Modeling Laterality of the Globus Pallidus Internus in Patients With Parkinson's Disease.

OBJECTIVE: Neurosurgical interventions such as deep brain stimulation surgery of the globus pallidus internus (GPi) play an important role in the treatment of medically refractory Parkinson's disease (PD), and require high targeting accuracy. Variability in the laterality of the GPi across patients with PD has not been well characterized. The aim of this report is to identify factors that may contribute to differences in position of the motor region of GPi. MATERIALS AND METHODS: The charts and operative reports of 101 PD patients following deep brain stimulation surgery (70 males, aged 11-78 years) representing 201 GPi were retrospectively reviewed. Data extracted for each subject include age, gender, anterior and posterior commissures (AC-PC) distance, and third ventricular width. Multiple linear regression, stepwise regression, and relative importance of regressors analysis were performed to assess the predictive ability of these variables on GPi laterality. RESULTS: Multiple linear regression for target vs. third ventricular width, gender, AC-PC distance, and age were significant for normalized linear regression coefficients of 0.333 (p < 0.0001), 0.206 (p = 0.00219), 0.168 (p = 0.0119), and 0.159 (p = 0.0136), respectively. Third ventricular width, gender, AC-PC distance, and age each account for 44.06% (21.38-65.69%, 95% CI), 20.82% (10.51-35.88%), 21.46% (8.28-37.05%), and 13.66% (2.62-28.64%) of the R2 value, respectively. Effect size calculation was significant for a change in the GPi laterality of 0.19 mm per mm of ventricular width, 0.11 mm per mm of AC-PC distance, 0.017 mm per year in age, and 0.54 mm increase for male gender. CONCLUSION: This variability highlights the limitations of indirect targeting alone, and argues for the continued use of MRI as well as intraoperative physiological testing to account for such factors that contribute to patient-specific variability in GPi localization.

Ictal onset patterns of local field potentials, high frequency oscillations, and unit activity in human mesial temporal lobe epilepsy.

OBJECTIVE: To characterize local field potentials, high frequency oscillations, and single unit firing patterns in microelectrode recordings of human limbic onset seizures. METHODS: Wide bandwidth local field potential recordings were acquired from microelectrodes implanted in mesial temporal structures during spontaneous seizures from six patients with mesial temporal lobe epilepsy. RESULTS: In the seizure onset zone, distinct epileptiform discharges were evident in the local field potential prior to the time of seizure onset in the intracranial EEG. In all three seizures with hypersynchronous (HYP) seizure onset, fast ripples with incrementally increasing power accompanied epileptiform discharges during the transition to the ictal state (p < 0.01). In a single low voltage fast (LVF) onset seizure a triad of evolving HYP LFP discharges, increased single unit activity, and fast ripples of incrementally increasing power were identified ~20 s prior to seizure onset (p < 0.01). In addition, incrementally increasing fast ripples occurred after seizure onset just prior to the transition to LVF activity (p < 0.01). HYP onset was associated with an increase in fast ripple and ripple rate (p < 0.05) and commonly each HYP discharge had a superimposed ripple followed by a fast ripple. Putative excitatory and inhibitory single units could be distinguished during limbic seizure onset, and heterogeneous shifts in firing rate were observed during LVF activity. SIGNIFICANCE: Epileptiform activity is detected by microelectrodes before it is detected by depth macroelectrodes, and the one clinically identified LVF ictal onset was a HYP onset at the local level. Patterns of incrementally increasing fast ripple power are consistent with observations in rats with experimental hippocampal epilepsy, suggesting that limbic seizures arise when small clusters of synchronously bursting neurons increase in size, coalesce, and reach a critical mass for propagation.

Acute Ischemic Stroke During Deep Brain Stimulation Surgery of Globus Pallidus Internus: Report of 5 Cases.

BACKGROUND: Cerebrovascular accident (CVA) is a potentially devastating complication of deep brain stimulation (DBS) surgery. Although there are substantial data reporting the incidence and cause of hemorrhagic CVA, reports of acute ischemic infarctions during DBS implantation surgery are rare. OBJECTIVE: To present a series of 5 patients who experienced clinically significant ischemic CVA during microelectrode-guided globus pallidus internus (GPi) DBS, and evaluate the potential risk factors and mechanisms. METHODS: A retrospective analysis of GPi DBS surgeries performed between June 2010 and February 2015 at UCLA Medical Center and June 2010 and February 2014 at Cedars-Sinai Medical Centers was performed to identify stroke risk factors. Statistical analysis was performed, comparing the stroke group with all patients undergoing GPi DBS. RESULTS: All 5 patients developed acute onset of lethargy, dysarthria, and contralateral facial and/or hemibody weakness intraoperatively. Computed tomographic scans in all cases were negative for hemorrhage. Magnetic resonance images obtained in 3 patients revealed infarction in the posterior limb of the internal capsule. During the time period analyzed, a total of 234 GPi leads were placed in 129 patients, yielding a 2.14% rate of ischemic stroke per lead. No statistically significant risk factors were identified in the stroke group. Given the variability of symptom onset during surgery, the mechanism is not clear, but it could be related to compression, compromise, or vasospasm of lenticulostriate arteries and/or anterior choroidal branches near the GPi target. CONCLUSION: Ischemic stroke in GPi DBS is a significant complication for clinicians to be aware of and discuss with their patients preoperatively.

Eyelid apraxia associated with deep brain stimulation of the periaqueductal gray area.

We report a patient with eyelid apraxia following deep brain stimulation of the periaqueductal gray area. Based on the position of our electrode, we argue that the phenomenon is linked to inhibition of the nearby central caudal nucleus of the oculomotor nucleus by high frequency stimulation.

Human hypocretin and melanin-concentrating hormone levels are linked to emotion and social interaction.

The neurochemical changes underlying human emotions and social behaviour are largely unknown. Here we report on the changes in the levels of two hypothalamic neuropeptides, hypocretin-1 and melanin-concentrating hormone, measured in the human amygdala. We show that hypocretin-1 levels are maximal during positive emotion, social interaction and anger, behaviours that induce cataplexy in human narcoleptics. In contrast, melanin-concentrating hormone levels are minimal during social interaction, but are increased after eating. Both peptides are at minimal levels during periods of postoperative pain despite high levels of arousal. Melanin-concentrating hormone levels increase at sleep onset, consistent with a role in sleep induction, whereas hypocretin-1 levels increase at wake onset, consistent with a role in wake induction. Levels of these two peptides in humans are not simply linked to arousal, but rather to specific emotions and state transitions. Other arousal systems may be similarly emotionally specialized.

Hypothalamic deep brain stimulation reduces weight gain in an obesity-animal model.

Prior studies of appetite regulatory networks, primarily in rodents, have established that targeted electrical stimulation of ventromedial hypothalamus (VMH) can alter food intake patterns and metabolic homeostasis. Consideration of this method for weight modulation in humans with severe overeating disorders and morbid obesity can be further advanced by modeling procedures and assessing endpoints that can provide preclinical data on efficacy and safety. In this study we adapted human deep brain stimulation (DBS) stereotactic methods and instrumentation to demonstrate in a large animal model the modulation of weight gain with VMH-DBS. Female Göttingen minipigs were used because of their dietary habits, physiologic characteristics, and brain structures that resemble those of primates. Further, these animals become obese on extra-feeding regimens. DBS electrodes were first bilaterally implanted into the VMH of the animals (n = 8) which were then maintained on a restricted food regimen for 1 mo following the surgery. The daily amount of food was then doubled for the next 2 mo in all animals to produce obesity associated with extra calorie intake, with half of the animals (n = 4) concurrently receiving continuous low frequency (50 Hz) VMH-DBS. Adverse motoric or behavioral effects were not observed subsequent to the surgical procedure or during the DBS period. Throughout this 2 mo DBS period, all animals consumed the doubled amount of daily food. However, the animals that had received VMH-DBS showed a cumulative weight gain (6.1±0.4 kg; mean ± SEM) that was lower than the nonstimulated VMH-DBS animals (9.4±1.3 kg; p<0.05), suggestive of a DBS-associated increase in metabolic rate. These results in a porcine obesity model demonstrate the efficacy and behavioral safety of a low frequency VMH-DBS application as a potential clinical strategy for modulation of body weight.

Memory enhancement and deep-brain stimulation of the entorhinal area.

BACKGROUND: The medial temporal structures, including the hippocampus and the entorhinal cortex, are critical for the ability to transform daily experience into lasting memories. We tested the hypothesis that deep-brain stimulation of the hippocampus or entorhinal cortex alters memory performance. METHODS: We implanted intracranial depth electrodes in seven subjects to identify seizure-onset zones for subsequent epilepsy surgery. The subjects completed a spatial learning task during which they learned destinations within virtual environments. During half the learning trials, focal electrical stimulation was given below the threshold that elicits an afterdischarge (i.e., a neuronal discharge that occurs after termination of the stimulus). RESULTS: Entorhinal stimulation applied while the subjects learned locations of landmarks enhanced their subsequent memory of these locations: the subjects reached these landmarks more quickly and by shorter routes, as compared with locations learned without stimulation. Entorhinal stimulation also resulted in a resetting of the phase of the theta rhythm, as shown on the hippocampal electroencephalogram. Direct hippocampal stimulation was not effective. In this small series, no adverse events associated with the procedure were observed. CONCLUSIONS: Stimulation of the entorhinal region enhanced memory of spatial information when applied during learning. (Funded by the National Institutes of Health and the Dana Foundation.).

Multi-institutional evaluation of deep brain stimulation targeting using probabilistic connectivity-based thalamic segmentation.

OBJECT: Due to the lack of internal anatomical detail with traditional MR imaging, preoperative stereotactic planning for the treatment of tremor usually relies on indirect targeting based on atlas-derived coordinates. The object of this study was to preliminarily investigate the role of probabilistic tractography-based thalamic segmentation for deep brain stimulation (DBS) targeting for the treatment of tremor. METHODS: Six patients undergoing bilateral implantation of DBS electrodes in the thalamus for the treatment of upper-extremity tremor were studied. All patients underwent stereotactic surgical implantation using traditional methods (based on indirect targeting methodologies and intraoperative macrostimulation findings) that were programmed for optimal efficacy, independent of tractography-based segmentations described in this report. Connectivity-based thalamic segmentations were derived by identifying with which of 7 cortical target regions each thalamic voxel had the highest probability of connectivity. The authors retrospectively analyzed the location of the optimal contact for treatment of tremor with connectivity-based thalamic segmentations. Findings from one institution (David Geffen School of Medicine at UCLA) were validated with results from 4 patients at another institution (University of Virginia Health System). RESULTS: Of 12 electrodes implanted using traditional methodologies, all but one resulted in efficacious tremor control. Connectivity-based thalamic segmentation consistently revealed discrete thalamic regions having unique connectivity patterns with distinct cortical regions. Although the authors initially hypothesized that the most efficacious DBS contact for controlling tremor would colocalize with the thalamic region most highly connected with the primary motor cortex, they instead found it to highly colocalize with those thalamic voxels demonstrating a high probability of connectivity with premotor cortex (center-to-center distance: 0.36 ± 0.55 mm). In contrast to the high degree of colocalization with optimal stimulation site, the precise localization of the premotor cortex-defined thalamic region relative to the anterior and posterior commissures was highly variable. Having defined a connectivity-based target for thalamic stimulation in a cohort of patients at David Geffen School of Medicine at UCLA, the authors validated findings in 4 patients (5 electrodes) who underwent surgery at a different institution (University of Virginia Health System) by a different surgeon. CONCLUSIONS: This report identifies and provides preliminary external validation of a novel means of targeting a patient-specific therapeutic thalamic target for the treatment of tremor based on individualized analysis of thalamic connectivity patterns. This novel thalamic targeting approach is based on identifying the thalamic region with the highest probability of connectivity with premotor and supplementary motor cortices. This approach may prove to be advantageous over traditional preoperative methods of indirect targeting, providing patient-specific targets that could improve the precision, efficacy, and efficiency of deep brain stimulation surgery. Prospective evaluation and development of methodologies to make these analyses more widely available to neurosurgeons are likely warranted.

Accuracy of frame-based stereotactic magnetic resonance imaging vs frame-based stereotactic head computed tomography fused with recent magnetic resonance imaging for postimplantation deep brain stimulator lead localization.

BACKGROUND: Introduction of the portable intraoperative CT scanner provides for a precise and cost-effective way of fusing head CT images with high-tesla MRI for the exquisite definition of soft tissue needed for stereotactic targeting. OBJECTIVE: To evaluate the accuracy of stereotactic electrode placement in patients undergoing deep brain stimulation (DBS) by comparing frame-based postimplantation intraoperative CT (iCT) images fused to a recent 3T-MRI with frame-based postimplantation intraoperative MRI (iMRI) alone. METHODS: Frame-based DBS surgeries of 46 targets performed from February 8, 2007 to April 28, 2008 in 26 patients with the use of immediate postimplantation iMRI for target localization were compared with frame-based immediate postimplantation iCT fused with a recent 3T brain MRI for DBS localization of 50 targets performed from August 13, 2008 to February 18, 2010 in 26 patients. Pre- and postoperative mid anterior commissure-posterior commissure line coordinates and XYZ coordinates for preoperatively calculated DBS targets (intended target) and for the permanent DBS lead tips were determined. The differences between preoperative DBS target and postoperative permanent DBS lead-tip coordinates based on postimplantation intraoperative MRI for the MRI-alone group and based on postimplantation intraoperative CT fused to recent preoperative MRI in the CT-MRI group were measured. The t test and Yuen test were used for comparison. RESULTS: No statistically significant differences were found between the 2 groups when comparing the pre- and postperative changes in mid anterior commissure-posterior commissure line coordinates and XYZ coordinates. CONCLUSION: Postimplantation DBS lead localization and therefore targeting accuracy was not significantly different between frame-based stereotactic 1.5T-MRI and frame-based stereotactic head CT fused with recent 3T-MRI.

Diffusion tensor imaging and colored fractional anisotropy mapping of the ventralis intermedius nucleus of the thalamus.

BACKGROUND: The ventralis intermedius (VIM) nucleus of the thalamus is the primary surgical target for treatment of tremor. Most centers rely on indirect targeting based on atlas-defined coordinates rather than patient-specific anatomy, making intraoperative physiological mapping critical. Detailed identification of this target based on patient-specific anatomic features can help optimize the surgical treatment of tremor. OBJECTIVE: To study colored fractional anisotropic images and diffusion tensor imaging (DTI) tractography to identify characteristic magnetic resonance appearances of the VIM nucleus. METHODS: Four patients undergoing stereotactic surgery for essential tremor (ET) were retrospectively studied with analysis of magnetic resonance imaging-based colored fractional anisotropy (FA) images and fiber tractography. All were scanned with a 1.5-T magnetic resonance imaging unit, and all sequences were obtained before frame placement. Because the goal of this study was to identify the DTI characteristics of physiologically defined VIM nucleus, we selected and studied patients who had undergone DTI and had efficacious tremor control with intraoperative microlesioning effect and tremor reduction with less than 2.0-V stimulation. RESULTS: Analysis of color FA maps, which graphically illustrate fiber directionality, revealed consistent anatomic patterns. The region of the VIM nucleus can be seen as an intermediate region where there is a characteristic transition of color. Presumptive VIM nucleus interconnectivity with sensorimotor cortex and cerebellum was identified via the internal capsule and the superior cerebellar peduncle, respectively. FA maps could also be used to distinguish segments of gray matter, white matter, and gray-white matter boundaries. CONCLUSION: Analysis of DTI and FA maps on widely available 1.5-T magnetic resonance imaging yields clear identification of various structures key to neurosurgical targeting. Prospective evaluation of integrating DTI into neurosurgical planning may be warranted.

White matter connectivity of human hypothalamus.

The macroscopic extrinsic white matter connectivity and the internal structure of the hypothalamus are still incompletely defined in humans. We investigated whether in-vivo diffusion tensor imaging tractography provides evidence of systematization according to hypothalamic compartmentalization. Six defined hypothalamic macroscopic compartments, preoptic, supraoptic, anteroventral, anterodorsal, lateral and posterior, were probed, within the right and left hemispheres of 14 subjects. Important new insights into the macroscopic structure of hypothalamus and white matter connections were found; the preoptic, anteroventral, lateral and posterior compartments are strongly connected to the cortex. The anteroventral connects particularly to the prefrontal cortex while the preoptic compartment connects mainly to the deep anterior brain. The anterodorsal connects mainly to the medial thalamus and the midline gray matter. There is a rightward frontal trend of hemispheric connectivity for the preoptic, anteroventral and lateral compartments. These findings may aid new neuromodulation applications and understanding in brain connectomics.

Diffusion tensor imaging (DTI) and colored fractional anisotropy (FA) mapping of the subthalamic nucleus (STN) and the globus pallidus interna (GPi).

INTRODUCTION: The subthalamic nucleus (STN) and the globus pallidus internus (GPi) are the most common surgical targets for the treatment of Parkinson's disease. We studied directionally colored fractional anisotropy (FA) and diffusion tensor imaging (DTI) sequences to better target these anatomical regions. METHODS: Four patients undergoing stereotactic surgery for movement disorders were studied. Stereotactic targets and fiber tractography were determined on MRIs using the Schaltenbrand-Wahren atlas for definition in the iPlan software. In addition, post-operative imaging was fused to preoperative FA sequences for end-result identification. Axial, sagittal, and coronal images of the FA sequence were studied. DTI parameters used ranged from 2 to 4 mm for voxel size in the x/y/z planes, fiber length was kept constant at 15 mm and FA threshold of 0.25. RESULTS: Colored FA maps resulted in a key signature in and around the STN and GPi. Regions identified include, but were not limited to: the internal capsule, nigral projections, the thalamic fasciculus, Forel's fields H1 and H2, zona incerta, suthalamic fasciculus, tegmental tracts, and cerebello-rubro-thalamic tract. CONCLUSIONS: Colored FA maps allow a potential method to identify the STN and GPi accurately. DTI has proven to be a powerful tool that can be used to augment identification of the STN nucleus and GPi used for stereotactic surgery.

A role of diffusion tensor imaging in movement disorder surgery.

The safe and reversible nature of deep brain stimulation (DBS) has allowed movement disorder neurosurgery to become commonplace throughout the world. Fundamental understanding of individual patient's anatomy is critical for optimizing the effects and side effects of DBS surgery. Three patients undergoing stereotactic surgery for movement disorders, at the institution's intraoperative magnetic resonance imaging operating suite, were studied with fiber tractography. Stereotactic targets and fiber tractography were determined on preoperative magnetic resonance imagings using the Schaltenbrand-Wahren atlas for definition in the BrainLab iPlan software (BrainLAB Inc., Feldkirchen, Germany). Subthalamic nucleus, globus pallidus interna, and ventral intermediate nucleus targets were studied. Diffusion tensor imaging parameters used ranged from 2 to 8 mm for volume of interest in the x/y/z planes, fiber length was kept constant at 30 mm, and fractional anisotropy threshold varied from 0.20 to 0.45. Diffusion tensor imaging tractography allowed reliable and reproducible visualization and correlation between frontal eye field, premotor, primary motor, and primary sensory cortices via corticospinal tracts and corticopontocerebellar tracts. There is an apparent increase in the number of cortical regions targeted by the fiber tracts as the region of interest is enlarged. This represents a possible mechanism of the increased effects and side effects observed with higher stimulation voltages. Currently available diffusion tensor imaging techniques allow potential methods to characterize the effects and side effects of DBS. This technology has the potential of being a powerful tool to optimize DBS neurosurgery.

Stereotactic coordinates associated with facial musculature contraction during high-frequency stimulation of the subthalamic nucleus.

OBJECT: High-frequency stimulation of the subthalamic nucleus (STN) in patients with parkinsonian symptoms is often used to ameliorate debilitating motor symptoms associated with this condition. However, individual variability in the shape and orientation of this relatively small nucleus results in multiple side effects related to the spread of electrical current to surrounding structures. Specifically, contraction of the muscles of facial expression is noted in a small percentage of patients, although the precise mechanism remains poorly understood. METHODS: Facial muscle contraction was triggered by high-frequency stimulation of 49 contacts in 18 patients undergoing deep brain stimulation of the STN. The mean coordinates of these individual contacts relative to the anterior commissure-posterior commissure midpoint (also called the midcommissural point) were calculated to determine the location or structure(s) most often associated with facial contraction during physiological macrostimulation. RESULTS: The x, y, and z coordinates associated with contraction of the facial musculature were found to be 11.52, 1.29, and 1.15 mm lateral, posterior, and inferior to the midcommissural point, respectively. This location, along the lateral-anterior-superior border of the STN, may allow for the spread of electrical current to the fields of Forel, zona incerta, and/or descending corticospinal/corticobulbar tracts. Because stimulation of corticobulbar tracts produces similar findings, these results are best explained by the spread of electrical current to nearby internal capsule axons coursing lateral to the STN. CONCLUSIONS: Thus, if intraoperative deep brain stimulation lead testing results in facial musculature contraction, placement of the electrode in a more medial, posterior position may reduce the amount of current spread to corticobulbar fibers and resolve this side effect.

Infection following deep brain stimulator implantation performed in the conventional versus magnetic resonance imaging-equipped operating room.

OBJECT: Risk factors for deep brain stimulator (DBS) infection are poorly defined. Because DBS implants are not frequently performed in the MR imaging-equipped operating room (OR), no specific data about infection of DBS implants performed in the MR imaging environment are available in the literature. In this study the authors focus on the incidence of infection in patients undergoing surgery in the conventional versus MR imaging-equipped OR. METHODS: To identify cases of DBS-associated infection, the authors performed a retrospective cohort study with nested case-control analysis of all patients undergoing DBS implantation at the University of California Los Angeles Medical Center. Cases of DBS infection were identified using standardized clinical and microbiological criteria. RESULTS: Between January 1998 and September 2003, 228 DBSs were implanted. Forty-seven operations (20.6%) were performed in the conventional OR and 181 (79.4%) in the MR imaging-equipped OR. There was definite infection in 13 cases (5.7%) and possible infection in 7 cases (3%), for an overall infection rate of 8.7% (20 of 228 cases). There was no significant difference in infection rates in the conventional (7 [14.89%] of 47) versus MR imaging-equipped OR (13 [7.18%] of 181) (p = 0.7). Staphylococcus aureus was isolated in 62% of cases. Twelve of 13 confirmed cases underwent complete hardware removal. On case-control analysis, younger age (< or = 58.5 years) was a significant predictor of DBS infection (odds ratio 3.4, p = 0.027) CONCLUSIONS: Infection is a serious complication of DBS implantation and commonly requires device removal for cure. The authors found that DBS implantation can be safely performed in MR imaging-equipped suites, possibly allowing improved lead placement. Young age was associated with an increased risk of DBS infection.

Inter-racial, gender and aging influences in the length of anterior commissure-posterior commissure line.

OBJECTIVE: The length of anterior-posterior commissure (AC-PC) in racial groups, age, gender of patients with deep brain stimulation (DBS) and pallidotomy were investigated. METHODS: From January 1996 to December 2003, 211 patients were treated with DBS and pallidotomy. There were 160 (76%) Caucasians, 35 (17%) Hispanics, 12 (5%) Asians and 4 Blacks (2%). There were 88 males and 52 females in DBS-surgery group and 44 males, 27 females in pallidotomy group. Mean age was 58 year-old. There were 19 males and 19 females and mean age was 54.7 years in the control group. Measurements were made on MRI and @Target software. RESULTS: The average AC-PC distance was 24.89 mm (range 32 to 19), which increased with aging until 75 years old in Caucasian and also increased with aging in Hispanic, but the AC-PC distance peaked at 45 years old in Hispanic. The order of AC-PC distance were 25.2+/-2 mm in Caucasian, 24.6+/-2.24 mm in Asian, 24.53 mm in Black, 23.6+/-1.98 mm in Hispanic. The average AC-PC distance in all groups was 24.22 mm in female who was mean age of 56.35, 25.28 mm in male who was mean age of 60.19 and 24.5+/-2 mm in control group that was excluded because of the difference of thickness of slice. According to multiple regression analysis, the AC-PC distance was significantly correlated with age, race, and gender. CONCLUSION: The AC-PC distance is significantly correlated with age, gender, and race. The atlas of functional stereotaxis would be depended on the variation of indivisual brain that can influenced by aging, gender, and race.

High-resolution depth electrode localization and imaging in patients with pharmacologically intractable epilepsy.

Localization and targeting of depth electrodes in specific regions of the human brain is critical for accurate clinical diagnoses and treatment as well as for neuroscientific electrophysiological research. By using high-resolution magnetic resonance imaging combined with 2D computational unfolding, the authors present a method that improves electrode localization in the medial temporal lobe. This method permits visualization of electrode placements in subregions of the hippocampus and parahippocampal gyrus, allowing for greater specificity in relating electrophysiological and anatomical features in the human medial temporal lobe. Such methods may be extended to therapeutic procedures targeting specific neuronal circuitry in subfields of structures deep in the human brain.