Stereotactic Neurosurgery Research Articles

Contribution of subcortical structures to cognition assessed with invasive electrophysiology in humans

Implantation of deep brain stimulation (DBS) electrodes via stereotactic neurosurgery has become a standard procedure for the treatment of Parkinson's disease. More recently, the range of neuropsychiatric conditions and the possible target structures suitable for DBS have greatly increased. The former include obsessive compulsive disease, depression, obesity, tremor, dystonia, Tourette's syndrome and cluster-headache. In this article we argue that several of the target structures for DBS (nucleus accumbens, posterior inferior hypothalamus, nucleus subthalamicus, nuclei in the thalamus, globus pallidus internus, nucleus pedunculopontinus) are located at strategic positions within brain circuits related to motivational behaviors, learning, and motor regulation. Recording from DBS electrodes either during the operation or post-operatively from externalized leads while the patient is performing cognitive tasks tapping the functions of the respective circuits provides a new window on the brain mechanisms underlying these functions. This is exemplified by a study of a patient suffering from obsessive-compulsive disease from whom we recorded in a flanker task designed to assess action monitoring processes while he received a DBS electrode in the right nucleus accumbens. Clear error-related modulations were obtained from the target structure, demonstrating a role of the nucleus accumbens in action monitoring. Based on recent conceptualizations of several different functional loops and on neuroimaging results we suggest further lines of research using this new window on brain functions.

Computer-assisted stereotactic neurosurgery with framework neurosurgery navigation

Objective To evaluate mechanical registration in a stereotactic system with framework neurosurgery navigation, setting scalp markers as the mutual frame of reference. Materials and methods The system can automatically convert the coordinates of the stereotactic device and CT or MRI images, and realize computer-assisted neurosurgery by the stereotactic system (framework neurosurgery navigation). We set targets in the skull; seven patients were operated on by open-skull stereotactic neurosurgery for clinical trials. Three cases were operated on by this method; the other four cases were treated by this method and the ASA620S operation plan system at the same time as a comparison. Results The targets were accurately located in seven patients. Four patients underwent the two different localization methods; the probe directed equally accurately (vector error: 3.96 ± 1.90 vs. 3.26 ± 1.22, P = 0.06 > 0.05, paired t-test). All surgical procedures were successful. Conclusions Framework neurosurgery navigation has equal localization accuracy compared with the traditional stereotactic device. Framework neurosurgery navigation does not require installation of a stereotactic framework before imaging or narcotic intubation; this differs from the traditional stereotactic technique. It can alleviate patient suffering, shorten preparation time, benefit anesthesia, and aid patient positioning during surgery.

Diffuse reflectance spectroscopy measurements for tissue-type discrimination during deep brain stimulation

Diffuse reflectance spectroscopy as a method for improving intracerebral guidance during functional neurosurgery has been investigated. An optical probe was developed for measurements during stereotactic and functional neurosurgery in man. The aim of the study was to investigate the spectral differences between white and grey matter and between white matter and functional targets. Diffuse reflectance spectroscopy measurements in ten patients were recorded at incremental steps towards and in three different functional targets (STN, GPi and Zi). The recorded spectra along the trajectory were sorted into white or grey matter, based on preoperative MRI images or the recorded spectral shape and intensity. The difference between tissue types was calculated as a quotient. Significant intensity differences between white and grey matter were found to be at least 14% (p < 0.05) and 20% (p < 0.0001) for MRI and spectral-sorted data respectively. The reflectance difference between white matter and the functional targets of GPi was higher than for STN and Zi. The results indicate that diffuse reflectance spectroscopy has a potential to be developed to a suitable complement to other intracerebral guidance methods.

Extracellular spike microrecordings from the subthalamic area in Parkinson’s disease

Intraoperative neuronal microrecordings can help in localizing the subthalamic nucleus (STN) during stereotactic neurosurgery for deep-brain stimulation (DBS) in Parkinson’s disease. To obtain quantitative information on neuronal spike descriptors, we systematically analysed neuronal spikes in the STN and substantia nigra pars reticulata (SNr) in 31 sides of the brain in awake patients undergoing stereotactic neurosurgery for DBS electrode implantation. In these two structures we evaluated spike amplitude, area, duration, rise time and mean total firing rate. The recording spike density was higher in the STN than in the SNr (94% vs. 28%). Microelectrode recordings showed a larger spike area and amplitude in the SNr than in the STN ([mean ± SD] amplitude: 46.7 ± 31.1 vs. 36.3 ± 29.6 μV; area: 25.6 ± 24.2 vs. 36.7 ± 21.4 μVmsec), a higher total firing rate at rest in the SNr than in the STN (78.6 ± 53.5 vs. 61.9 ± 40.8 Hz), and a longer duration and rise time in the SNr than in the STN (duration: 2.0 ± 1 vs. 1.3 ± 0.6 ms; rise time: 0.95 ± 0.6 vs. 0.67 ± 0.3 ms). Our analysis also revealed sex-related differences in the studied spike descriptors, paralleling recent findings from deep electroencephalography recordings. In the STN, males had larger spike area and amplitude (amplitude: 41.97 ± 32.57 vs. 26.2 ± 19.7 μV; area: 31.8 ± 26.4 vs. 13.0 ± 10.6 μVmsec), whereas females had higher mean total firing rate (66.7 ± 53.4 vs. 82.8 ± 50.8 Hz). Our results have implications for clinical practice and the development of algorithms for the neurophysiological identification of the STN during stereotactic neurosurgery for Parkinson’s disease, based on the on-line automated computation of multiple spike-variables.

Pedunculopontine nucleus microelectrode recordings in movement disorder patients

The pedunculopontine nucleus (PPN) lies within the brainstem reticular formation and is involved in the motor control of gait and posture. Interest has focused recently on the PPN as a target for implantation of chronic deep brain stimulation (DBS) electrodes for Parkinson's disease (PD) and progressive supranuclear palsy (PSP) therapy. The aim of this study was to examine the neurophysiology of the human PPN region and to identify neurophysiological landmarks that may aid the proper placement of DBS electrodes in the nucleus for the treatment of PD and PSP. Neuronal firing and local field potentials were recorded simultaneously from two independently driven microelectrodes during stereotactic neurosurgery for implantation of a unilateral DBS electrode in the PPN in five PD patients and two PSP patients. Within the PPN region, the majority (57%) of the neurons fired randomly while about 21% of the neurons exhibited 'bursty' firing. In addition, 21% of the neurons had a long action potential duration and significantly lower firing rate suggesting they were cholinergic neurons. A change in firing rate produced by passive and/or active contralateral limb movement was observed in 38% of the neurons that were tested in the PPN region. Interestingly, oscillatory local field potential activity in the beta frequency range ( approximately 25 Hz) was also observed in the PPN region. These electrophysiological characteristics of the PPN region provide further support for the proposed role of this region in motor control. It remains to be seen to what extent the physiological characteristics of the neurons and the stimulation-evoked effects will permit reliable identification of PPN and determination of the optimal target for DBS therapy.

Applicants for stereotactic neurosurgery for psychiatric disorders: role of the Flemish advisory board

Research on stereotactic neurosurgery for psychiatric disorders (SNPD) is rapidly evolving. Knowledge on patients undergoing SNPD is of crucial importance. We describe applicants for SNPD and examine the necessity for a multidisciplinary advisory board. Summary of the current practice of the Flemish advisory board (SNPD committee) and analysis of a questionnaire investigating the attitude of clinicians on SNPD. In 7 years, 91 applications were submitted, nine patients did not fulfill diagnostic criteria for OCD, 65 patients received a positive recommendation, 50 SNPD procedures were performed. The prevalence of SNPD in the current year in Belgium is 0.6/million inhabitants. Ninety-seven per cent of clinicians consider the expertise and advice of the SNPD committee essential for indication setting. Forty-four percent of clinicians consider referral of a patient for capsulotomy, 82% for electrical brain stimulation. Neurosurgery is exclusively considered for severe, treatment-refractory psychiatric disorders. Clinicians consider the SNPD committee essential in the decision-making process prior to intervention.

Human pallidothalamic and cerebellothalamic tracts: anatomical basis for functional stereotactic neurosurgery

Anatomical knowledge of the structures to be targeted and of the circuitry involved is crucial in stereotactic functional neurosurgery. The present study was undertaken in the context of surgical treatment of motor disorders such as essential tremor (ET) and Parkinson’s disease (PD) to precisely determine the course and three-dimensional stereotactic localisation of the cerebellothalamic and pallidothalamic tracts in the human brain. The course of the fibre tracts to the thalamus was traced in the subthalamic region using multiple staining procedures and their entrance into the thalamus determined according to our atlas of the human thalamus and basal ganglia [Morel (2007) Stereotactic atlas of the human thalamus and basal ganglia. Informa Healthcare Inc., New York]. Stereotactic three-dimensional coordinates were determined by sectioning thalamic and basal ganglia blocks parallel to stereotactic planes and, in two cases, by correlation with magnetic resonance images (MRI) from the same brains prior to sectioning. The major contributions of this study are to provide: (1) evidence that the bulks of the cerebellothalamic and pallidothalamic tracts are clearly separated up to their thalamic entrance, (2) stereotactic maps of the two tracts in the subthalamic region, (3) the possibility to discriminate between different subthalamic fibre tracts on the basis of immunohistochemical stainings, (4) correlations of histologically identified fibre tracts with high-resolution MRI, and (5) evaluation of the interindividual variability of the fibre systems in the subthalamic region. This study should provide an important basis for accurate stereotactic neurosurgical targeting of the subthalamic region in motor disorders such as PD and ET.

Cervical Dystonia in Bechterev Disease Resulting in Atlantoaxial Rotatory Subluxation and Cranio-Cervical Osseous Fusion

We report on a 46-year-old man with atlantoaxial rotatory subluxation and cranio-cervical osseous fusion secondary to cervical dystonia (CD) and concomitant ankylosing spondylitis (AS). To describe treatment of CD under these unusual circumstances. CD may cause several complications due to enhanced spinal degeneration. Primary and secondary nonresponders to conservative treatment may benefit from neurosurgical procedures including denervation procedures or functional stereotactic neurosurgery. However, if spinal fixation has occurred, usually, treatment of dystonia is considered to be not appropriate. Nevertheless, in the rare case, neurosurgical intervention may still be useful to improve dystonic pain. After a 4-year history of severe CD, the head was rotated to the left in a rigidly fixed position. Three-dimensionally rendered computed tomography imaging studies revealed fixed rotation of the occiput and the C1 vertebra at an angle of 45 degrees to the C2 vertebra. There was abnormal ossification of the facet joints and the ligaments of the odontoid. The patient experienced marked relief of his neck pain after deactivation of the dystonic right sternocleidomastoid muscle by partial myectomy and the left posterior neck muscles by selective posterior ramisectomy. Although rare, the concomitant occurrence of AS and CD should alert treating physicians and result in timely treatment of dystonia.

Towards construction of an ideal stereotactic brain atlas

The role of the brain atlas is changing in many aspects with the advancements in stereotactic and functional neurosurgery. Therefore, there is a critical need to construct a new atlas. This paper addresses the definition and construction of an atlas, ideal (in our opinion) for stereotactic and functional neurosurgery. The essence of the new atlas is not only its population-based structural and functional content, but also its continuous "self-updatability" with the new clinical results obtained. The ideal atlas defined here contains four major components: brain models, knowledge database, tools, and clinical results. Towards its creation, a multi-atlas is proposed. The construction of the initial version of the multi-atlas is detailed with the probabilistic functional atlas (PFA), interpolated Talairach-Tournoux atlas, and enhanced Schaltenbrand-Wahren atlas. These atlases are put in a spatial register by matching their AC-PC distances and heights of the thalamus; the Schaltenbrand coronal and sagittal microseries are scaled laterally to match the target structure centroids with the locations of the best targets of the PFA. Construction of an initial version of the ideal stereotactic atlas is feasible at present from the available resources. To achieve that, our three atlases (PFA, Talairach and Schaltenbrand) are enhanced and combined together. A single lateral scaling factor per target structure is feasible to co-register the Schaltenbrand atlas with PFA in four situations (compensated against the third ventricle, non-compensated, bilateral, and non-bilateral). The STN has to be stretched by 18% more than the VIM on the Schaltenbrand coronal microseries, and the VIM has to be compressed by 13% less than the STN on the Schaltenbrand sagittal microseries. The new multi-atlas can potentially be more useful than the currently employed atlases and will facilitate further development of the ideal atlas for stereotactic and functional neurosurgery.

Brain shift: an error factor during implantation of deep brain stimulation electrodes

The goal of this study was to focus on the tendency of brain shift during stereotactic neurosurgery and the shift's impact on the unilateral and bilateral implantation of electrodes for deep brain stimulation (DBS). Eight unilateral and 10 bilateral DBS electrodes at 10 nuclei ventrales intermedii and 18 subthalamic nuclei were implanted in patients at Kaizuka Hospital with the aid of magnetic resonance (MR) imaging-guided and microelectrode-guided methods. Brain shift was assessed as changes in the 3D coordinates of the anterior and posterior commissures (AC and PC) with MR images before and immediately after the implantation surgery. The positions of the implanted electrodes, based on the midcommissural point and AC-PC line, were measured both on x-ray films (virtual position) during surgery and the postoperative MR images (actual position) obtained on the 7th day postoperatively. Contralateral and posterior shift of the AC and PC were the characteristics of unilateral and bilateral procedures, respectively. The authors suggest the following. 1) The first unilateral procedure elicits a unilateral air invasion, resulting in a contralateral brain shift. 2) During the second procedure in the bilateral surgery, the contralateral shift is reset to the midline and, at the same time, the anteroposterior support by the contralateral hemisphere against gravity is lost due to a bilateral air invasion, resulting in a significant posterior (caudal) shift. To note the tendency of the brain to shift is very important for accurate implantation of a DBS electrode or high frequency thermocoagulation, as well as for the prediction of therapeutic and adverse effects of stereotactic surgery.

What the future holds for deep brain stimulation

For 20 years, deep brain stimulation (DBS) at high frequency has been developed as a substitute for the classical lesioning methods previously used in stereotactic and functional neurosurgery. This method has proven its efficacy, based on its reversibility and adaptability: two factors that are responsible for low morbidity. The method has been initially developed for and applied to movement disorders in several target areas; such as the thalamus, the pallidum and the subthalamic nucleus. It has now also been extended to other indications, such as epilepsy, dystonias and cluster headache and, more recently, to psychiatric disorders, such as obsessive–compulsive disorder, Gilles de la Tourette tics and depression. Several other disorders are currently under investigation and these may become new indications in the future. The mechanism of action is likely to be complex; associating cell-firing inhibition, neurotransmitter depletion, jamming and excitation of inhibitory pathways that lead to functional inhibition, mimicking the effects of lesioning of the stimulated structures. High-frequency stimulation of the subthalamic nucleus induces neuroprotection in animal models but has not yet been demonstrated in human patients suffering from Parkinson’s disease. Technological development will enhance and refine the effects of high-frequency stimulation, and allow further extension of this method to new targets and new indications.

Move it! Fellowship in stereotactic and functional neurosurgery, Vancouver

Functional neurosurgery refers to the branch of brain surgery that involves the modulation of nervous tissue activity. This form of surgery is mainly used in the treatment of movement disorders, epilepsy and pain. Traditionally, this was achieved by injuring key structures in the central or peripheral nervous system. More recently, electrical stimulation has been used to alter the activities of different neuronal groups and deep brain stimulation is now an established treatment option for Parkinson's disease.

Deep Brain Stimulation for Treatment of Parkinson's Disease

Dr. Pilitsis is a Fellow in Stereotactic and Functional Neurosurgery, and Dr. Bakay is A. Watson Armour III and Sarah Armour Presidential Chair and Residency Research Director, Department of Neurosurgery, Rush University, Suite 970, Professional Building, 1725 W. Harrison Street, Chicago, IL 60612; E-mail: roy_bakay_rush.edu. Dr. Pilitsis has disclosed that she is the recipient of grant/research support from Medtronic, Inc. Dr. Bakay has disclosed that he has no significant relationships with or financial interests in any commercial organizations related to this educational activity. Lippincott CME Institute, Inc., has identified and resolved all faculty conflicts of interest regarding this educational activity. Category: Functional

Intracerebral Microvascular Measurements during Deep Brain Stimulation Implantation using Laser Doppler Perfusion Monitoring

The aim of the study was to investigate if laser Doppler perfusion monitoring (LDPM) can be used in order to differentiate between gray and white matter and to what extent microvascular perfusion can be recorded in the deep brain structures during stereotactic neurosurgery. An optical probe constructed to fit in the Leksell® Stereotactic System was used for measurements along the trajectory and in the targets (globus pallidus internus, subthalamic nucleus, zona incerta, thalamus) during the implantation of deep brain stimulation leads (n = 22). The total backscattered light intensity (TLI) reflecting the grayness of the tissue, and the microvascular perfusion were captured at 128 sites. Heartbeat-synchronized pulsations were found at all perfusion recordings. In 6 sites the perfusion was more than 6 times higher than the closest neighbor indicating a possible small vessel structure. TLI was significantly higher (p < 0.005) and the perfusion significantly lower (p < 0.005) in positions identified as white matter in the respective MRI batch. The measurements imply that LDPM has the potential to be used as an intracerebral guidance tool.

Antecedentes, desarrollo y situación actual de la robótica en cirugía

Robotic is an antique concep. The first robots used in surgery were precise path systems in the 80's. Stereotactic neurosurgery was the first field applying this devices. Based on these more complex devices were built: AESOP and Endoassist help the surgeon during the surgery. The surgical assistant will not fatigue and there will be no tremor of the camera. Finally the master-slave devices were developed. They are the most commenly used all around the world. They are involved many types surgery in. To evaluate the cost-effectiviness of robotics in surgery is our responsability. Robotics provides many advantages but also has a few disadvantages including expense.

COMBINED X-RAY AND MAGNETIC RESONANCE IMAGING FACILITY

To assess the feasibility of a hybrid imaging setup combining x-ray and magnetic resonance imaging (MRI) in the setting of both stereotactic and functional neurosurgery. A combined x-ray and MRI scanning facility with a trolley system for a fast patient transfer between both modalities was installed in a neurosurgical setting. A registration algorithm for fusion of MRI scans and x-ray images was derived for augmentation of fluoroscopic x-ray projection images with MRI scan data, such as anatomic structures and planned probe trajectories. Phantom measurements were obtained between both modalities for estimation of registration accuracy. Practical application of our system in stereotactic and functional neurosurgery was tested in brachytherapy, deep brain stimulation, and motor cortex stimulation. Phantom measurements yielded a mean spatial deviation of 0.7 +/- 0.3 mm with a maximum deviation of 1.1 mm for MRI scans versus x-rays. Augmentation of x-ray images with MRI scan data allowed intraoperative verification of the planned trajectory and target in three types of neurosurgical procedures: positioning iodine seeds in brachytherapy in one case with cerebellar metastasis, placement of electrodes for deep brain stimulation in two cases of advanced Parkinson's disease, and placement of an epidural grid for motor cortex stimulation in two cases of intractable pain. Combined x-ray and MRI-guided stereotactic and functional neurosurgery is feasible. Augmentation of x-ray projection images with MRI scan data, such as planned probe trajectories and MRI scan segmented anatomic structures may be beneficial for probe guidance in stereotactic and functional neurosurgery.

Treatment for ataxia in multiple sclerosis

Disabling tremor or ataxia is common in multiple sclerosis (MS) and up to 80% of patients experience tremor or ataxia at some point during their disease. A variety of treatments are available, ranging from pharmacotherapy or stereotactic neurosurgery to neurorehabilitation. To assess the efficacy and tolerability of both pharmacological and non-pharmacologic treatments of ataxia in patients with MS. The following electronic resources were searched: Cochrane MS Group trials register (June 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 2, 2006), National Health Service National Research Register (NRR) including the Medical Research Council Clinical Trials Directory (Issue 2, 2006), MEDLINE (January 1996 to June 2006), and EMBASE (Jan 1988 to June 2006). Manual searches of bibliographies of relevant articles, pertinent medical and neurology journals and abstract books of major neurology and MS conferences (2001-2006) were also performed. Direct communication with experts and drug companies was sought. Blinded, randomised trials which were either placebo-controlled or which compared two or more treatments were included. Trials testing pharmacological agents must have had both participant and assessor blinding. Trials testing surgical interventions or effects of physiotherapy, where participants could not have been blinded to the treatment, must have had independent assessors who were blinded to the treatment. Cross-over trials were included. Three independent reviewers extracted data and the findings of the trials were summarised. A meta-analysis was not performed due to the inadequacy of outcome measures and methodological problems with the studies reviewed. Ten randomised controlled trials met the inclusion criteria. Six placebo-controlled studies (pharmacotherapy) and four comparative studies (one stereotactic neurosurgery and three neurorehabilitation) were reviewed. No standardised outcome measures were used across the studies. In general, pharmacotherapies were unrewarding and data on neurosurgery or rehabilitation is insufficient to lead to a change in practice. The absolute and comparative efficacy and tolerability of pharmacotherapies to treat ataxia in MS are poorly documented and no recommendations can be made to guide prescribing. Although studies on neurosurgery and neurorehabilitation showed promising results, the absolute indications for treating with those methods cannot be developed. Standardised, well validated measures of ataxia and tremor need to be developed and employed in larger randomised controlled trials with careful blinding.

504 定位脳手術中の脳移動の動態解析(OS8-1:デジタルヒューマン,オーガナイズドセッション8:デジタルヒューマン)

504 定位脳手術中の脳移動の動態解析(OS8-1:デジタルヒューマン,オーガナイズドセッション8:デジタルヒューマン)

Stereotactic neurosurgery for disabling tremor in multiple sclerosis: thalamotomy or deep brain stimulation?

Disabling tremor is common in multiple sclerosis and up to 75% of patients experience tremor at some point during their disease. The treatment of this tremor, however, remains challenging. Pharmacotherapy in general has been disappointing and stereotactic neurosurgery is becoming increasingly popular. However, the results of stereotactic treatments reported are variable and no systematic review has been performed. The aim of this study was to assess the role of thalamotomy and deep brain stimulation in the treatment of tremor in multiple sclerosis, and to compare the differences in efficacy and safety between the two techniques. We identified the relevant published studies and cases by searching the MEDLINE, EMBASS and the references lists of related articles, and performed a systematic review and assessment of the full texts of all articles selected. Initial tremor suppression was seen in 93.8% of patients who had thalamotomy and 96% in those who had deep brain stimulation. A total of 63.5% of patients had persistent tremor suppression at 12 months or more after thalamotomy. Twelve results for deep brain stimulation were not available in the reviewed literature. Functional improvement was seen only in 47.8% of those who underwent thalamotomy as opposed to 85.2% of those who had deep brain stimulation. While three of the four reported deaths were in patients who underwent thalamotomy, three of the four procedure-related haemorrhages followed DBS. Other common adverse effects like hemiparesis, dysarthria, swallowing difficulties, balance disorder, etc., was reported in both procedures. Numerous studies have attempted to assess the efficacy and safety of thalamotomy and DBS in the treatment of MS tremor, but no standardized outcome measures were used. Nonetheless, the data suggest that both thalamotomy and thalamic DBS are comparable procedures for tremor suppression and that adverse effects can occur with both procedures.

3.241 Localization of spontaneous thalamic local field potential activity recorded during stereotactic functional neurosurgery

3.241 Localization of spontaneous thalamic local field potential activity recorded during stereotactic functional neurosurgery