戴立体定向仪磁共振复查在帕金森病丘脑底核脑深部刺激术中的意义

目的 ;总结帕金森病丘脑底核脑深部刺激(Subthalamic nucleus deep brain sti mulation,STN-DBS)术中戴立体定向仪磁共振复查对提高定位准确性、降低手术并发症的意义。方法 2003年~2009年共有124例帕金森病病人进行了丘脑底核DBS手术,共191侧,其中男性64例,女性60例,年龄45~80岁,平均65.5±8.7岁。术中未用微电极记录技术,但均戴立体定向仪磁共振复查,对电极触点目标位和实际位有明显误差的病人术中进行必要的调整。结果治疗效果与国内外文献报道类似,但无脑出血等手术并发症。结论术中戴立体定向仪复查磁共振既可以提高定位的准确性,又可以避免应用微电极记录可能导致的脑出血并发症、缩短手术时间。     

Role of Microelectrode Recording in Deep Brain Stimulation of the Pedunculopontine Nucleus: A Physiological Study of Two Cases

BackgroundDeep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) has been reported to improve gait disturbances in Parkinson's disease (PD); however, there are controversies on the radiological and electrophysiological techniques for intraoperative and postoperative confirmation of the target and determination of optimal stimulation parameters.ObjectivesWe investigated the correlation between the location of the estimated PPN (ePPN) and neuronal activity collected during intraoperative electrophysiological mapping to evaluate the role of microelectrode recording (MER) in identifying the effective stimulation site in two PD patients.Materials and MethodsBilateral PPN DBS was performed in two patients who had suffered from levodopa refractory gait disturbance. They had been implanted previously with DBS in the internal globus pallidus and the subthalamic nucleus, respectively. The PPN was determined on MRI and identified by intraoperative MER. Neuronal activity recorded was analyzed for mean discharge rate, bursting, and oscillatory activity. The effects were assessed by clinical ratings for motor signs before and after surgery.ResultsThe PPN location was detected by MER. Groups of neurons characterized by tonic discharges were found 9–10 mm below the thalamus. The mean discharge rate in the ePPN was 19.1 ± 15.1 Hz, and 33% of the neurons of the ePPN responded with increased discharge rate during passive manipulation of the limbs and orofacial structures. PPN DBS with bipolar stimulation at a frequency range 10–30 Hz improved gait disturbances in both patients. Although PPN DBS provided therapeutic effects post-surgery in both cases, the effects waned after a year in case 1 and three years in case 2.ConclusionsEstimation of stimulation site within the PPN is possible by combining physiological guidance using MER and MRI findings. The PPN is a potential target for gait disturbances, although the efficacy of PPN DBS may depend on the location of the electrode and the stimulation parameters.     

Effect of globus pallidus internus stimulation on neuronal activity in the pedunculopontine tegmental nucleus in the primate model of Parkinson's disease

The pedunculopontine tegmental nucleus (PPN) is being explored as a site for deep brain stimulation (DBS) for the treatment of patients with medically refractory gait and postural abnormalities (MRGPA) associated with Parkinson's disease (PD). The PPN is involved in initiation and modulation of gait and other stereotyped motor behaviors and is inter-connected with the pallido-thalamo-cortical circuit. Internal segment of the globus pallidus (GPi) DBS is effective at treating the motor signs associated with PD, however its impact on MRGPA is limited and its effect on PPN neuronal activity is unknown. The current work characterizes the effect of therapeutically-effective GPi DBS on PPN neuronal activity in a single rhesus monkey made parkinsonian using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). A scaled-down, quadripolar DBS lead was implanted into sensorimotor GPi under electrophysiological and stereotactic guidance. Single-neuron activity was recorded from PPN before, during and after DBS. GPi DBS reduced the mean discharge rate of PPN neurons from 16.8 Hz to 12.8 Hz, with 30 (66.7%) neurons showing a decreased mean rate, 3 (6.7%) increased and 12 (26.7%) unchanged. Consistent with known GABAergic projections from GPi to PPN, and with previous observations that stimulation increases output from the stimulated structure, GPi DBS suppressed activity in the PPN. The present observations, together with previous reports of improvement in MRGPA during low frequency stimulation in PPN, suggest that activation of PPN output may be required to improve MRGPA and may account for the lack of improvement in MRGPA typically observed with GPi or subthalamic nucleus (STN) DBS.     

Deep brain stimulation of globus pallidus interna, subthalamic nucleus, and pedunculopontine nucleus for Parkinson's disease: which target?

Deep brain stimulation (DBS) is an accepted therapy for people with Parkinson's disease (PD) motor symptoms that are refractory to pharmacologic therapy. Standard DBS targets are globus pallidus interna (GPi) and subthalamic nucleus (STN). The pedunculopontine nucleus (PPN) is being investigated as a novel target. Which target provides the best outcomes is unknown. The utility of GPi and STN as targets has been confirmed in numerous studies, including randomized comparisons of GPi DBS and STN DBS that demonstrated no difference in motor outcomes. DBS at either site improves appendicular motor symptoms, but beneficial effects on axial manifestations of PD such as postural instability or gait dysfunction (PIGD) are less apparent. PPN has been introduced as a DBS target due to failure of GPi and STN DBS to improve PIGD. Small observational studies indicate improved PIGD with PPN DBS, but small blinded trials show only subjective reduction in falls with no other impact on PIGD or other PD manifestations. No single DBS target is superior to the others. Each target offers relative advantages. Further studies are needed to better define the roles of each target, particularly PPN. Choice of target should be individualized according to providers' preferences and patients' needs.     

Role of electrode design on the volume of tissue activated during deep brain stimulation

Deep brain stimulation (DBS) is an established clinical treatment for a range of neurological disorders. Depending on the disease state of the patient, different anatomical structures such as the ventral intermediate nucleus of the thalamus (VIM), the subthalamic nucleus or the globus pallidus are targeted for stimulation. However, the same electrode design is currently used in nearly all DBS applications, even though substantial morphological and anatomical differences exist between the various target nuclei. The fundamental goal of this study was to develop a theoretical understanding of the impact of changes in the DBS electrode contact geometry on the volume of tissue activated (VTA) during stimulation. Finite element models of the electrodes and surrounding medium were coupled to cable models of myelinated axons to predict the VTA as a function of stimulation parameter settings and electrode design. Clinical DBS electrodes have cylindrical contacts 1.27 mm in diameter (d) and 1.5 mm in height (h). Our results show that changes in contact height and diameter can substantially modulate the size and shape of the VTA, even when contact surface area is preserved. Electrode designs with a low aspect ratio (d/h) maximize the VTA by providing greater spread of the stimulation parallel to the electrode shaft without sacrificing lateral spread. The results of this study provide the foundation necessary to customize electrode design and VTA shape for specific anatomical targets, and an example is presented for the VIM. A range of opportunities exist to engineer DBS systems to maximize stimulation of the target area while minimizing stimulation of non-target areas. Therefore, it may be possible to improve therapeutic benefit and minimize side effects from DBS with the design of target-specific electrodes.     

MRI- and skull x-ray-based approaches to evaluate the position of deep brain stimulation electrode contacts--a technical note

Deep brain stimulation (DBS) has developed into an established therapy for the treatment of movement disorders, most commonly Parkinson's disease and tremor of different etiology. The subthalamic nucleus (STN) has evolved as the preferred target for DBS in patients with idiopathic Parkinson's disease. The principal target for DBS in tremor patients is the ventrolateral thalamus which has been explored for ablative procedures (thalamotomy) for some decades. Detailed information about the exact site of chronic stimulation, i.e. the location of the active electrode contacts, are important to map the actual subcortical structures modulating the therapeutic effects of DBS. We compared two different methods not requiring intra-operative teleradiography to determine the stereotactic coordinates of single electrode contacts, (i) correlation of pre- and post-operative MRI, and (ii) post-operative stereotactic skull x-ray. For seven patients implanted bilateral with quadripolar DBS electrodes the coordinates for each contact were determined by both approaches. This revealed for a total of 56 electrode contacts a median euclidean 3D-difference between both methods of 1.18 mm (range 0.42 to 1.93 mm). These data suggest that both approaches may be used to determine the position of single electrode contacts.     

Gait-Phase Modulates Alpha and Beta Oscillations in the Pedunculopontine Nucleus

The pedunculopontine nucleus (PPN) is a reticular collection of neurons at the junction of the midbrain and pons, playing an important role in modulating posture and locomotion. Deep brain stimulation of the PPN has been proposed as an emerging treatment for patients with Parkinson''s disease (PD) or multiple system atrophy (MSA) who have gait-related atypical parkinsonian syndromes. In this study, we investigated PPN activities during gait to better understand its functional role in locomotion. Specifically, we investigated whether PPN activity is rhythmically modulated by gait cycles during locomotion. PPN local field potential (LFP) activities were recorded from PD or MSA patients with gait difficulties during stepping in place or free walking. Simultaneous measurements from force plates or accelerometers were used to determine the phase within each gait cycle at each time point. Our results showed that activities in the alpha and beta frequency bands in the PPN LFPs were rhythmically modulated by the gait phase within gait cycles, with a higher modulation index when the stepping rhythm was more regular. Meanwhile, the PPN–cortical coherence was most prominent in the alpha band. Both gait phase-related modulation in the alpha/beta power and the PPN–cortical coherence in the alpha frequency band were spatially specific to the PPN and did not extend to surrounding regions. These results suggest that alternating PPN modulation may support gait control. Whether enhancing alternating PPN modulation by stimulating in an alternating fashion could positively affect gait control remains to be tested.SIGNIFICANCE STATEMENT The therapeutic efficacy of pedunculopontine nucleus (PPN) deep brain stimulation (DBS) and the extent to which it can improve quality of life are still inconclusive. Understanding how PPN activity is modulated by stepping or walking may offer insight into how to improve the efficacy of PPN DBS in ameliorating gait difficulties. Our study shows that PPN alpha and beta activity was modulated by the gait phase, and that this was most pronounced when the stepping rhythm was regular. It remains to be tested whether enhancing alternating PPN modulation by stimulating in an alternating fashion could positively affect gait control.     

Typical variations of subthalamic electrode location do not predict limb motor function improvement in Parkinson’s disease

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for patients with medically refractory Parkinson’s disease (PD). The degree to which the anatomic location of the DBS electrode tip determines the improvement of contralateral limb movement function has not been defined. This retrospective study was performed to address this issue. Forty-two DBS electrode tips in 21 bilaterally implanted patients were localized on postoperative MRI. The postoperative and preoperative planning MRIs were merged with the Stealth FrameLink 4.0 stereotactic planning workstation (Medtronic Inc., Minneapolis, MN, USA) to determine the DBS tip coordinates. Stimulation settings were postoperatively optimized for maximal clinical effect. Patients were videotaped 1 year postoperatively and assessed by a movement disorder neurologist blinded to electrode tip locations. The nine limb-related components of the Unified PD Rating Scale Part III were tabulated to obtain a limb score, and the electrode tip locations associated with the 15 least and 15 greatest limb scores were evaluated. Two-tailed t-tests revealed no significant difference in electrode tip location between the two groups in three-dimensional distance (p = 0.759), lateral–medial (x) axis (p = 0.983), anterior–posterior (y) axis (p = 0.949) or superior–inferior (z) axis (p = 0.894) from the intended anatomical target. The range of difference in tip location and limb scores was extensive. Our results suggest that anatomic targeting alone may provide the same clinical efficacy as is achieved by “fine-tuning” DBS placement with microelectrode recording to a specific target.     

Tractography-Activation Models Applied to Subcallosal Cingulate Deep Brain Stimulation

Deep brain stimulation (DBS) of the subcallosal cingulate white matter (SCCWM) is an experimental therapy for major depressive disorder (MDD). The specific axonal pathways that mediate the anti-depressant effects of DBS remain unknown. Patient-specific tractography-activation models (TAMs) are a new tool to help identify pathways modulated by DBS. TAMs consist of four basic components: 1) anatomical and diffusion-weighted imaging data acquired on the patient; 2) probabilistic tractography from the brain region surrounding the implanted DBS electrode; 3) finite element models of the electric field generated by the patient-specific DBS parameter settings; and 4) application of the DBS electric field to multi-compartment cable models of axons, with trajectories defined by the tractography, to predict action potential generation in specific pathways. This study presents TAM predictions from DBS of the SCCWM in one MDD patient. Our findings suggest that small differences in electrode location can generate substantial differences in the directly activated pathways.     

Mood response to deep brain stimulation of the subthalamic nucleus in Parkinson's disease

Deep brain stimulation of the subthalamic nucleus (STN DBS) in Parkinson's disease (PD) improves motor functioning but has variable effects on mood. Little is known about the relationship between electrode contact location and mood response. The authors identified the anatomical location of electrode contacts and measured mood response to stimulation with the Visual Analog Scale in 24 STN DBS PD patients. Participants reported greater positive mood and decreased anxiety and apathy with bilateral and unilateral stimulation. Left DBS improved mood more than right DBS. Right DBS-induced increase in positive mood was related to more medial and dorsal contact locations. These results highlight the functional heterogeneity of the STN.     

Deep brain stimulation in the treatment of movement disorders]

The introduction of deep brain stimulation (DBS) was a historical step forward for the treatment of advanced and medically intractable movement disorders that include Parkinson's disease, dystonias, essential tremor, and Holmes' tremor. DBS is able to modulate the target region electrically in a reversible and adjustable fashion in contrast to an irreversible and destructive lesioning procedure. In the treatment of movement disorders, the potential targets are the thalamic ventral intermediate nucleus (Vim), globus pallidus internus (GPi), subthalamic nucleus (STN), pedunculopontine nucleus (PPN), and thalamic Vo-complex nucleus. With the development of DBS technology and stereotactic neurosurgical techniques, its therapeutic efficacy has been increased while reducing surgical complications. DBS has become an established therapy for disabling movement disorders and is currently being used to treat neuropsychiatric disorders.     

Stereotactic neurosurgical planning, recording, and visualization for deep brain stimulation in non-human primates

Methodologies for stereotactic neurosurgery and neurophysiological microelectrode recordings (MER) in non-human primate research typically rely on brain atlases that are not customized to the individual animal, and require paper records of MER data. To address these limitations, we developed a software tool (Cicerone) that enables simultaneous interactive 3D visualization of the neuroanatomy, neurophysiology, and neurostimulation data pertinent to deep brain stimulation (DBS) research studies in non-human primates. Cicerone allows for analysis of co-registered magnetic resonance images (MRI), computed tomography (CT) scans, 3D brain atlases, MER data, and DBS electrode(s) with predictions of the volume of tissue activated (VTA) as a function of the stimulation parameters. We used Cicerone to aid the implantation of DBS electrodes in two parkinsonian rhesus macaques, targeting the subthalamic nucleus in one monkey and the globus pallidus in the other. Cicerone correctly predicted the anatomical position of 79% and 73% of neurophysiologically defined MER sites in the two animals, respectively. In contrast, traditional 2D print atlases achieved 61% and 48% accuracy. Our experience suggests that Cicerone can improve anatomical targeting, enhance electrophysiological data visualization, and augment the design of stimulation experiments.     

Somatosensory evoked potential and clinical changes after electrode implant in basal ganglia of parkinsonian patients

Median nerve somatosensory evoked potentials (SEPs) were recorded in three parkinsonian patients who underwent electrode implant in the subthalamic nucleus and/or globus pallidus for chronic deep brain stimulation (DBS). SEPs were evoked before surgery, in a medication-free condition, and after the functional stereotactic procedure, before beginning DBS. In order to evaluate the timing of the SEP changes after the electrode implant, in three further patients SEPs were recorded within the operating theater, before and immediately after the implantation. Patients' symptoms improved immediately after the electrode implant, and both N20 and N30 amplitudes increased in the postsurgical SEP recording. The clinical and neurophysiological effects observed after surgery, before commencing DBS, can be explained by microdamage in the target nucleus following the electrode implant. They occurred also in the patients studied in the operating theater, thus suggesting that they occur immediately after the stereotactic procedure. Our results suggest that the circuitries between the basal ganglia and the primary sensorimotor cortex may be modified not only by DBS but also by microdamage due to surgery and that they exert an important influence on SEP amplitude.     

Deep Brain Stimulation and Levodopa Affect Gait Variability in Parkinson Disease Differently

BackgroundBoth dopaminergic medication and subthalamic nucleus (STN) deep brain stimulation (DBS) can improve the amplitude and speed of gait in Parkinson disease (PD), but relatively little is known about their comparative effects on gait variability. Gait irregularity has been linked to the degeneration of cholinergic neurons in the pedunculopontine nucleus (PPN).ObjectivesThe STN and PPN have reciprocal connections, and we hypothesized that STN DBS might improve gait variability by modulating PPN function. Dopaminergic medication should not do this, and we therefore sought to compare the effects of medication and STN DBS on gait variability.Materials and MethodsWe studied 11 patients with STN DBS systems on and off with no alteration to their medication, and 15 patients with PD without DBS systems on and off medication. Participants walked for two minutes in each state, wearing six inertial measurement units. Variability has previously often been expressed in terms of SD or coefficient of variation over a testing session, but these measures conflate long-term variability (eg, gradual slowing, which is not necessarily pathological) with short-term variability (true irregularity). We used Poincaré analysis to separate the short- and long-term variability.ResultsDBS decreased short-term variability in lower limb gait parameters, whereas medication did not have this effect. In contrast, STN DBS had no effect on arm swing and trunk motion variability, whereas medication increased them, without obvious dyskinesia.ConclusionsOur results suggest that STN DBS acts through a nondopaminergic mechanism to reduce gait variability. We believe that the most likely explanation is the retrograde activation of cholinergic PPN projection neurons.     

Deep Brain Stimulation of the Subthalamic and Pedunculopontine Nucleus in a Patient with Parkinson's Disease

Deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) is a novel therapy developed to treat Parkinson''s disease. We report a patient who underwent bilateral DBS of the PPN and subthalamic nucleus (STN). He suffered from freezing of gait (FOG), bradykinesia, rigidity and mild tremors. The patient underwent bilateral DBS of the PPN and STN. We compared the benefits of PPN-DBS and STN-DBS using motor and gait subscores. The PPN-DBS provided modest improvements in the gait disorder and freezing episodes, while the STN-DBS failed to improve the dominant problems. This special case suggests that PPN-DBS may have a unique role in ameliorating the locomotor symptoms and has the potential to provide improvement in FOG.     

Chronic subthalamic high-frequency deep brain stimulation in Parkinson's disease – a histopathological study

This study describes the pathological findings in the brain of a patient with Parkinson's disease (PD) treated with bilateral subthalamic high-frequency deep brain stimulation (STN DBS) for 29 months prior to death. After routine neuropathological examination, tissue blocks containing the electrode tracts, the subthalamic nucleus (STN), the substantia nigra and the pre-frontal cortex were paraffin embedded and cut into 5- μ m-thick serial sections and stained with several conventional staining methods and immunohistochemistry. Bilateral nigral depigmentation, cell loss and Lewy body formation confirmed the diagnosis of PD. Microscopic evaluation furthermore confirmed the location of the electrodes in the STN. The electrode tracts were surrounded by a 150- μ m-wide glial fibrillary acidic protein (GFAP)-positive capsule consisting of a thin collagen layer lining the lumen of the tract, whilst an area with few cells and axons constituted the capsule wall towards the surrounding normal brain tissue. The brain tissue appeared normal outside the capsule boundaries with no difference in areas of stimulation compared with areas of no stimulation. Our results correspond with previous studies performed after fewer months of STN DBS and indicate mild histopathological changes in the vicinity of the electrode tract, appearing to result from the electrode placement and not from the electrical stimulation.     

Pedunculopontine stimulation from primate to patient

Deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) is a novel neurosurgical therapy developed to address symptoms of gait freezing and postural instability in Parkinson’s disease and related disorders. Here we summarise our non-human primate investigations of relevance to our surgical targeting of the PPN and relate the primate research to initial clinical experience of PPN DBS.     

Subthalamic nucleus stimulation in Parkinson''s disease: Postoperative CT–MRI fusion images confirm accuracy of electrode placement using intraoperative multi-unit recording

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is increasingly used to treat advanced Parkinson's disease (PD). The optimal method for targeting the STN before implanting the definitive DBS electrode is still a matter of debates. Beside methods of direct visualization of the nucleus based on stereotactic magnetic resonance imaging (MRI), the most often used technique for targeting STN consists in recording single-cell activity along exploratory tracks of 10-15mm in length, centered on the theoretical or MRI-defined target coordinates. Single-unit recordings with a microelectrode present various drawbacks. They are time-consuming if correctly performed and a single-cell precision is probably superfluous, taking into account the size of the implanted electrode. In this study, we present an original method of recording and quantification of a multi-unit signal recorded intraoperatively with a semi-microelectrode for targeting the STN. Twelve patients with advanced PD have been included and assessed clinically before and one year after bilateral STN-DBS electrode implantation guided by multi-unit electrophysiological recordings. After one year of chronic stimulation, all patients showed a marked clinical improvement. The motor score of the unified Parkinson's disease rating scale decreased by more than 57% and the required levodopa-equivalent daily dose by 59.5% in on-stimulation off-medication condition compared to off-stimulation off-medication condition. The accuracy of STN-DBS lead placement was confirmed on postoperative computed tomography (CT) scans, which were fused to preoperative T2-weighted MRI. The boundaries of the STN were easily determined by an increase in multi-unit signal amplitude, which was observed on average from 0.492mm below the rostral border of the STN down to 0.325mm above its caudal border. Signal amplitude significantly increased at the both rostral and caudal STN margins (P<0.05) and the level of neuronal activity easily distinguished inside from outside the nucleus. This study showed that STN boundaries could be adequately determined on the basis of intraoperative multi-unit recording with a semi-microelectrode. The accuracy of our method used for positioning DBS electrodes into the STN was confirmed both on CT-MRI fusion images and on the rate of therapeutic efficacy.     

Contact dependent reproducible hypomania induced by deep brain stimulation in Parkinson's disease: clinical, anatomical and functional imaging study

Hypomanic symptoms depending on anatomical location of contacts are reported in patients with Parkinson's disease (PD) treated by deep brain stimulation (DBS) of the subthalamic nucleus (STN). However, the underlying cortical and subcortical dysfunction is debated. In this study, five PD patients implanted with DBS-STN who presented with reversible and reproducible hypomanic symptoms after stimulation of specific 'manic' contacts were investigated. Hypomanic symptoms were assessed using the Bech and Rafaelsen Mania Scale (MAS). Three dimensional anatomical location of 'euthymic' and 'manic' contacts, after matching the postoperative CT scan with the preoperative stereotactic MRI, and a H(2)(15)O positron emission tomography (PET) study testing 'euthymic' and 'manic' contacts, were performed. Under 'euthymic' conditions, MAS score (mean±SD) was 0.6±0.5 compared with 7.8±3.1 under 'manic' conditions. Nine of 10 'manic' contacts were located in the substantia nigra, mainly in its ventral part. PET showed that hypomania was associated with strong asymmetrical cerebral activation involving preferentially the right hemisphere and was mediated by activation of the anterior cingulate and medial prefrontal cortex. The present study demonstrates the role of the subcortical structures in the genesis of hypomania in PD patients treated with DBS and stresses the involvement of the substantia nigra.     

脑深部刺激术靶点定位准确性的术中确认方法

目的探讨脑深部电刺激术（DBS）术中确认靶点定位准确性的方法。方法回顾性分析146例帕金森病人行丘脑底核（STN）DBS治疗的靶点定位经验。单侧手术70例,双侧76例。术前采用磁共振扫描图像直接定位和坐标值定位相结合的方法计算靶点坐标。术中行微电极记录细胞外放电．通过观察微毁损效应、刺激效果和副作用。及X-线透视和戴立体定向仪行MRI复查进行靶点确认。结果术中电极植入后。112例肌张力增高病人中的76例、91例震颤病人中的44例和109例运动迟缓病人中的40例观察到微毁损效应。术中刺激时,106例仍有肌张力增高病人中的103例、86例震颤病人中的64例和109例运动迟缓病人中的69例有相应改善。在1．0—3．5V低电压刺激下,仅出现轻度异动副作用27例;而3．5—10．0V高电压刺激下出现各种明显副作用126例,其中3例因副作用阈值低而调整坐标。16例术中行C形臂X-线透视,发现电极过深4例;87例行术中MRJ复查,发现电极过深16例,电极偏内3例。结论微毁损效应、刺激效果和副作用观察有助于判断电极位置的准确性;戴立体定向仪MRI复查能替代微电极记录,及时纠正电极位置偏差,减少脑出血和2次手术定位。