Dissection using pulsed radiofrequency energy device (PlasmaBlade) is safe and efficient in experimental revision neuromodulation implant surgery

BACKGROUND

The use of functional neurosurgical implants has increased over the past 10 years. PlasmaBlade is an innovative electrosurgical appliance harnessing pulsed radiofrequency (RF) energy. Our aim was to assess the risk of damage to neuromodulation hardware during PlasmaBlade dissection.

MATERIALS AND METHODS

A simulated setting with chicken breast threaded with different hardware and PlasmaBlade used in three configurations. . Post dissection, the wires were inspected naked eye and under an operating microscope. The induced current was assessed contemporaneously using an oscilloscope.

RESULTS

Five surgeons tested the PlasmaBlade at different generator settings. Sixty dissections were undertaken. No structural damage or induced current was identified at CUT 3/4, COAG 5. At CUT 6, COAG 5 and during dissection in a perpendicular orientation with prolonged hardware contact, opacification of insulation material occurred in 15/20 dissections. There was no dissolution of insulation even at this setting. On deviation from Medtronic advice, hardware damaged occurred if one was reckless with the PlasmaBlade.

CONCLUSION

When using the recommended settings and operational technique, PlasmaBlade dissection did not cause any damage to implant wiring/tubing in this simulated setting. This report seeks to add to clinical data suggesting PlasmaBlade is safe for dissection around deep brain stimulator (DBS), vagal nerve stimulator (VNS), and spinal cord stimulator (SCS) hardware.

Intracerebral hemorrhage after deep brain stimulation surgery guided with microelectrode recording: analysis of 297 procedures

OBJECTIVES

Report the incidence of symptomatic and asymptomatic intracerebral hemorrhage (ICH) in patients submitted to deep brain stimulation (DBS) guided with microelectrode recording (MER) with further analysis of potential risk factors, both inherent to the patient and related to the pathology and surgical technique.

METHODS

We performed a retrospective observational study. 297 DBS procedures were concluded in 277 patients in a single hospital centre between January 2010 and December 2020. All surgeries were guided with MER. We analysed the incidence of symptomatic and asymptomatic ICH and its correlation to age, sex, diagnosis, hypertension and perioperative hypertension, diabetes, dyslipidaemia, antiplatelet drugs, anatomic target, and number of MER trajectories.

RESULTS

There were a total of 585 electrodes implanted in 277 patients. 16 ICH were observed, of which 6 were symptomatic and 10 asymptomatic, none of which incurred in permanent neurological deficit. The location of the hemorrhage varied between cortical and subcortical plans, always in relation with the trajectory or the final position of the electrode. The incidence of symptomatic ICH per lead-implantation was 1%, and the CT-scan demonstrated asymptomatic ICH in 1.7% more patients. Male patients or with hypertension are 2.7 and 2.2 times more likely to develop ICH, respectively. However, none of these characteristics has been shown to have a statistically significant association with the occurrence of ICH, as well as age, diagnosis, diabetes, dyslipidaemia, antiplatelet drugs, anatomic target, number of MER trajectories and perioperative hypertension.

CONCLUSIONS

MER-guided DBS is a safe technique, with low incidence of ICH and no permanent deficits in our study. Hypertension and male sex seem to be risk factors for the development of ICH in this surgery. Nevertheless, no statistically significant factors were found for the occurrence of this complication.

Neuromodulation in Parkinson's disease targeting opioid and cannabinoid receptors, understanding the role of NLRP3 pathway: a novel therapeutic approach

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta, resulting in motor and non-motor symptoms. Although levodopa is the primary medication for PD, its long-term use is associated with complications such as dyskinesia and drug resistance, necessitating novel therapeutic approaches. Recent research has highlighted the potential of targeting opioid and cannabinoid receptors as innovative strategies for PD treatment. Modulating opioid transmission, particularly through activating µ (MOR) and δ (DOR) receptors while inhibiting κ (KOR) receptors, shows promise in preventing motor complications and reducing L-DOPA-induced dyskinesia. Opioids also possess neuroprotective properties and play a role in neuroprotection and seizure control. Similar to this, endocannabinoid signalling via CB1 and CB2 receptors influences the basal ganglia and may contribute to PD pathophysiology, making it a potential therapeutic target. In addition to opioid and cannabinoid receptor targeting, the NLRP3 pathway, implicated in neuroinflammation and neurodegeneration, emerges as another potential therapeutic avenue for PD. Recent studies suggest that targeting this pathway holds promise as a therapeutic strategy for PD management. This comprehensive review focuses on neuromodulation and novel therapeutic approaches for PD, specifically highlighting the targeting of opioid and cannabinoid receptors and the NLRP3 pathway. A better understanding of these mechanisms has the potential to enhance the quality of life for PD patients.

Intrathecal catheter for severe low back pain during deep brain stimulation placement: illustrative case

BACKGROUND

Deep brain stimulation (DBS) is a U.S. Food and Drug Administration–approved therapy for medically refractory Parkinson’s disease, essential tremor, and other neurological conditions. The procedure requires prolonged immobility and can result in significant patient discomfort, potentially limiting patient selection. In addition, surgical requirements necessitate avoidance of medications that may alter or suppress the patient’s arousal or baseline tremor during macrostimulation testing.

OBSERVATIONS

In this study, the authors describe the use of continuous spinal anesthesia with local anesthetic to manage a patient with severe back pain who was intolerant of semisupine position during stereotactic computed tomography and stage 1 of DBS placement.

LESSONS

Continuous spinal anesthesia is an effective strategy to manage patients with severe back pain undergoing DBS surgery for upper extremity motor symptoms.

Optimized Propofol Anesthesia Increases Power of Subthalamic Neuronal Activity in Patients with Parkinson's Disease Undergoing Deep Brain Stimulation

Introduction

Propofol is a general anesthetic option for deep brain stimulation (DBS) of the subthalamic nucleus (STN) of patients with Parkinson's disease (PD). However, its effects on STN activity and neuropsychological outcomes are controversial. The optimal propofol anesthesia for asleep DBS is unknown. This study investigated the safety and effectiveness of an optimized propofol anesthesia regimen in asleep DBS.

Methods

This retrospective study enrolled 68 PD patients undergoing bilateral STN-DBS surgery. All patients received local scalp anesthesia, with (asleep group, n = 35) or without (awake group, n = 33) propofol-remifentanil general anesthesia by target-controlled infusion under electroencephalogram monitoring. The primary outcome was subthalamic neuronal spiking characterization during microelectrode recording. The secondary outcomes were clinical outcomes including motor, cognition, mind, sleep, and quality of life at 6 months.

Results

Significantly increased delta and theta power were obtained under propofol anesthesia (awake vs. asleep group, mean ± standard deviation; delta: 31.97 ± 9.87 vs. 39.77 ± 10.56, p < 0.01; theta: 21.09 ± 5.55 vs. 24.82 ± 6.63, p = 0.01). After excluding the influence of confounding factors of age and preoperative motor scores, there was a statistically significant influence on the delta, theta, and alpha power of STN neuronal activity under different anesthesia regimens (delta: β = 2.64, p < 0.01; theta: β = 2.11, p < 0.01; alpha: β = 1.42, p = 0.01). There were no differences in modified burst index, firing rate, tract numbers of microelectrode recording, and other clinical outcomes between the two groups.

Conclusion

Optimized propofol anesthesia enhanced the delta, theta, and alpha power in STN compared with the awake technique and likely contributed to target recognition under propofol anesthesia. These results demonstrate that propofol is suitable, but needs to be optimized, for asleep STN-DBS.

Trial Registration

Chinese Clinical Trial Registry Identification number: ChiCTR2100045942. Registered 29 April 2021–Retrospectively registered

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00259-y.

Comparison of recovery profiles in patients with Parkinson's disease for 2 types of neuromuscular blockade reversal agent following deep brain stimulator implantation

As an anesthetic reversal agent, there are concerns with cholinesterase inhibitors regarding worsening of Parkinson's disease (PD)-related symptoms. Sugammadex, a relatively new reversal agent, does not inhibit acetylcholinesterase and does not require co-administration of an antimuscarinic agent. The present study compared the recovery profiles of 2 agents initially administered for reversal of neuromuscular blockade in patients with advanced PD who underwent deep brain stimulator implantation.A total of 121 patients with PD who underwent deep brain stimulator implantation were retrospectively analyzed. Patients were divided into 1 of 2 groups according to the type of neuromuscular blockade reversal agent (pyridostigmine vs sugammadex) initially administered. Recovery profiles reflecting time to extubation, reversal failure at first attempt, and hemodynamic stability, including incidence of hypertension or tachycardia during the emergence period, were compared.Time to extubation in the sugammadex group was significantly shorter (P < .001). In the sugammadex group, reversal failure at first attempt did not occur in any patient, while it occurred in seven (9.7%) patients in the pyridostigmine group (P = .064), necessitating an additional dose of pyridostigmine (n = 3) or sugammadex (n = 4). The incidence of hemodynamic instability during anesthetic emergence was significantly lower in the sugammadex group than in the pyridostigmine group (P = .019).Sugammadex yielded a recovery profile superior to that of pyridostigmine during the anesthesia emergence period in advanced PD patients. Sugammadex is also likely to be associated with fewer adverse effects than traditional reversal agents, which in turn would also improve overall postoperative management in this patient population.

Effect of Anesthesia on Microelectrode Recordings during Deep Brain Stimulation Surgery in Tourette Syndrome Patients

BACKGROUND

Deep brain stimulation (DBS) is an accepted treatment for patients with medication-resistant Tourette syndrome (TS). Sedation is commonly required during electrode implantation to attenuate anxiety, pain, and severe tics. Anesthetic agents potentially impair the quality of microelectrode recordings (MER). Little is known about the effect of these anesthetics on MER in patients with TS. We describe our experience with different sedative regimens on MER and tic severity in patients with TS.

METHODS

The clinical records of all TS patients who underwent DBS surgery between 2010 and 2018 were reviewed. Demographic data, stimulation targets, anesthetic agents, perioperative complications, and MER from each hemisphere were collected and analyzed. Single-unit activity was identified by filtering spiking activity from broadband MER data and principal component analysis with K-means clustering. Vocal and motor tics which caused artifacts in the MER data were manually selected using visual and auditory inspection.

RESULTS

Six patients underwent bilateral DBS electrode implantation. In all patients, the target was the anterior internal globus pallidus. Patient comfort and hemodynamic and respiratory stability were maintained with conscious sedation with one or more of the following anesthetic drugs: propofol, midazolam, remifentanil, clonidine, and dexmedetomidine. Good quality MER and clinical testing were obtained in 9 hemispheres of 6 patients. In 3 patients, MER quality was poor on one side.

CONCLUSION

Cautiously applied sedative drugs can provide patient comfort, hemodynamic and respiratory stability, and suppress severe tics, with minimal interference with MER.

Vestibular Implantation and the Feasibility of Fluoroscopy-Guided Electrode Insertion

Recent research has shown promising results for the development of a clinically feasible vestibular implant in the near future. However, correct electrode placement remains a challenge. It was shown that fluoroscopy was able to visualize the semicircular canal ampullae and electrodes, and guide electrode insertion in real time. Ninety-four percent of the 18 electrodes were implanted correctly (<1.5 mm distance to target). The median distances were 0.60 mm, 0.85 mm, and 0.65 mm for the superior, lateral, and posterior semicircular canal, respectively. These findings suggest that fluoroscopy can significantly improve electrode placement during vestibular implantation.

Eye Movements Evoked by Pulsed Infrared Radiation of the Rat Vestibular System

Light at infrared wavelengths has been demonstrated to modulate the pattern of neural signals transmitted from the angular motion sensing semicircular canals of the vestibular system to the brain. In the present study, we have characterized physiological eye movements evoked by focused, pulsed infrared radiation (IR) stimuli directed at an individual semicircular canal in a mammalian model. Pulsed IR (1863 nm) trains were directed at the posterior semicircular canal in a rat using 200-400 µm optical fibers. Evoked bilateral eye movements were measured using a custom-modified video-oculography system. The activation of vestibulo-ocular motor pathways by frequency modulated pulsed IR directed at single posterior semicircular canals evoked significant, characteristic bilateral eye movements. In this case, the resulting eye movements were disconjugate with ipsilateral eye moving upwards with a rotation towards the stimulated ear and the contralateral eye moving downwards. The eye movements were stable through several hours of repeated stimulation and could be maintained with 30 + minutes of continuous, frequency-modulated IR stimulation. Following the measurements, the distance of the fiber from target structures and orientation of the beam relative to vestibular structures were determined using micro-computed tomography. Results highlight the spatial selectivity of optical stimulation. Our results demonstrate a novel strategy for direct optical stimulation of the vestibular pathway in rodents and lays the groundwork for future applications of optical neural stimulation in inner ear research and therapeutic applications.

Anaesthesiologist's Approach to Awake Craniotomy

Awake craniotomy, which was initially used for the surgical treatment of epilepsy, is performed for the resection of tumours in the vicinity of some eloquent areas of the cerebral cortex which is essential for language and motor functions. It is also performed for stereotactic brain biopsy, ventriculostomy, and supratentorial tumour resections. In some institutions, avoiding risks of general anaesthesia, shortened hospitalization and reduced use of hospital resources may be the other indications for awake craniotomy. Anaesthesiologists aim to provide safe and effective surgical status, maintaining a comfortable and pain-free condition for the patient during surgical procedure and prolonged stationary position and maintaining patient cooperation during intradural interventions. Providing anaesthesia for awake craniotomy require scalp blockage, specific sedation protocols and airway management. Long-acting local anaesthetic agents like bupivacaine or levobupivacaine are preferred. More commonly, propofol, dexmedetomidine and remifentanyl are used as sedative agents. A successful anaesthesia for awake craniotomy depends on the personal experience and detailed planning of the anaesthetic procedure. The aim of this review was to present an anaesthetic technique for awake craniotomy under the light of the literature.

Cautery selection for oculofacial plastic surgery in patients with implantable electronic devices

PURPOSE

To discover oculofacial plastic surgeon practice patterns for cautery selection in the setting of implantable electronic devices and present guidelines based on a review of current literature.

METHODS

A 10-Question web-based survey was sent to the email list serve of the American Society of Ophthalmic Plastic and Reconstructive Surgery to determine surgeon cautery preference in the setting of various implantable electronic devices and comfort level with the guidelines for cautery selection in their practice or institution. The relationship between survey questions was assessed for statistical significance using Pearson's Chi-square tests.

RESULTS

Two hundred ninety-three (41% response rate) surveys were completed and included for analysis. Greater than half of respondents either had no policy (36%) or were unaware of a policy (19%) in their practice or institution regarding cautery selection in patients with a cardiac implantable electronic device. Bipolar cautery was favored for use in patients with a cardiac implantable electronic device (79%-80%) and this number dropped in patients with implantable neurostimulators (30%). Overall, one-third of respondents did not feel comfortable with their practice/institution policy.

CONCLUSION

Choices and comfort level among oculofacial plastic surgeons for cautery selection in patients with implantable electronic devices vary considerably, and some choices may increase the risk for interference-related complications. Practice patterns vary significantly in the setting of a neurostimulator or cochlear implant, where interference can cause thermal injury to the brain and implant damage, respectively. Guidelines are proposed for cautery selection in patients with implantable electronic devices undergoing oculofacial plastic surgery.

Outcomes of Primary Total Knee Arthroplasty in Patients With Parkinson's Disease

BACKGROUND

Parkinson's disease is a degenerative disorder causing rigidity, bradykinesia, and tremor of the motor system. There is significant paucity of evidence regarding whether total knee arthroplasty (TKA) is of benefit in patients with both Parkinson's disease and osteoarthritis. We aimed to compare outcomes and complications of TKA between patients with Parkinson's disease and those without.

METHODS

A cohort of 43 knees from 35 patients with Parkinson's disease who received a primary TKA between January 2004 and December 2015 were retrospectively extracted from a private clinical database held by 2 surgeons and compared to an age and gender-matched control group of 50 knees from 41 patients. TKAs were performed by 2 surgeons at 1 tertiary private hospital.The indication for TKA in both groups was osteoarthritis. Difference between preoperative and 1-year range of movement (ROM) and 12-point Oxford Knee Score (OKS) was assessed using Student's unpaired t-test. Postoperative complications and revision procedures were also recorded during the follow-up period. The minimal clinically important difference for OKS at 1-year follow-up, defined as improvement of ≥6, was also assessed.

RESULTS

In the Parkinson's group, mean ROM improvement was 14° (100° preoperatively to 114° at 12 months), compared to 12° in the control group (102°-114°, respectively). Mean OKS improvement was 15 in the Parkinson's group (23 preoperatively to 38 at 12 months) compared to 17 in the control group (23 and 40, respectively.) No significant difference was identified between the 2 groups for either ROM (P = .96) or OKS (P = .45.) All Parkinson's patients achieved the minimal clinically important difference at 1-year follow-up. There were no mortalities during the study follow-up period and no significant difference in complication rates between the 2 groups (P = .41).

CONCLUSION

Parkinson's disease was not associated with poorer functional outcomes or increased complications compared to controls in our study. We suggest that Parkinson's disease is not an absolute contraindication to TKA.

Remifentanil Requirement for Inhibiting Responses to Tracheal Intubation and Skin Incision Is Reduced in Patients With Parkinson's Disease Undergoing Deep Brain Stimulator Implantation

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative disease affecting the quality of life in the elderly. We speculated that PD patients might have abnormal pharmacodynamics due to the degenerative neural system, and the present study was performed to investigate the pharmacodynamics of remifentanil in PD patients.

MATERIALS AND METHODS

Two arms of patients were recruited, including 31 PD patients undergoing pulse generator placement after deep brain stimulator implantation and 31 pair-controlled patients undergoing intracranial surgery without PD (NPD). Patients were anesthetized with target-controlled infusion of propofol and remifentanil. The effective concentration of remifentanil to inhibit responses to intubation and skin incision in 50% and 95% patients (EC50 and EC95) was determined by the up and down method.

RESULTS

Demographic data, bispectral index, and hemodynamic values were similar between the PD and the NPD groups. The average remifentanil concentration used in the PD group for tracheal intubation is significantly lower than in the NPD group (P<0.001). The EC50 for inhibiting the response to tracheal intubation were 1.86 ng/mL (95% confidential interval [CI], 1.77-1.96 ng/mL) in the PD group and 3.20 ng/mL (95% CI, 3.13-3.27 ng/mL) in the NPD group. The average remifentanil concentration used in the PD group for skin incision is significantly lower than in the NPD group (P<0.001). EC50 for inhibiting the response to skin incision were 2.17 ng/mL (95% CI, 2.09-2.25 ng/mL) in the PD group and 3.09 ng/mL (95% CI, 3.02-3.17 ng/mL) in the NPD group.

CONCLUSIONS

The remifentanil concentrations required for inhibiting responses to tracheal intubation and skin incision are reduced markedly in PD patients undergoing pulse generator placement (NCT01992692).

MRI-guided stereotactic neurosurgical procedures in a diagnostic MRI suite: Background and safe practice recommendations

The development of navigation technology facilitating MRI-guided stereotactic neurosurgery has enabled neurosurgeons to perform a variety of procedures ranging from deep brain stimulation to laser ablation entirely within an intraoperative or diagnostic MRI suite while having real-time visualization of brain anatomy. Prior to this technology, some of these procedures required multisite workflow patterns that presented significant risk to the patient during transport. For those facilities with access to this technology, safe practice guidelines exist only for procedures performed within an intraoperative MRI. There are currently no safe practice guidelines or parameters available for facilities looking to integrate this technology into practice in conventional MRI suites. Performing neurosurgical procedures in a diagnostic MRI suite does require precautionary measures. The relative novelty of technology and workflows for direct MRI-guided procedures requires consideration of safe practice recommendations, including those pertaining to infection control and magnet safety issues. This article proposes a framework of safe practice recommendations designed for assessing readiness and optimization of MRI-guided neurosurgical interventions in the diagnostic MRI suite in an effort to mitigate patient risk. The framework is based on existing clinical evidence, recommendations, and guidelines related to infection control and prevention, health care-associated infections, and magnet safety, as well as the clinical and practical experience of neurosurgeons utilizing this technology.

The Effects of Dexmedetomidine on Microelectrode Recordings of the Subthalamic Nucleus during Deep Brain Stimulation Surgery: A Retrospective Analysis

BACKGROUND

The placement of subthalamic nucleus (STN) deep brain stimulation (DBS) electrodes can be facilitated by intraoperative microelectrode recording (MER) of the STN.

OBJECTIVES

Optimal anesthetic management during surgery remains unclear because of a lack of quantitative data of the effect of anesthetics on MER. Therefore, we measured the effects of dexmedetomidine (DEX) on MER measures of the STN commonly taken intraoperatively.

METHODS

MER from 45 patients was retrospectively compared between patients treated with remifentanil (REMI) alone or both REMI and DEX, which are the 2 main standards of care at our center. The measures examined were population activity, such as root mean square, STN length, and number of passes yielding STN, and the single-neuron measures of firing rate and variability.

RESULTS

The addition of DEX does not affect population measures (number of passes: DEX+REMI, n = 68, REMI only, n = 154), or neuronal firing rates (number of neurons: DEX+REMI, n = 64, REMI only, n = 72), but firing rate variability was reduced.

CONCLUSIONS

In this cohort, population-based measures routinely used for electrode placement in the STN were unaffected by DEX when added to REMI. Neuronal firing rates were also unaffected, but their variability was reduced, even beyond 20 min after cessation.

Preanesthetic evaluation of a patient with a deep brain stimulator: a practical guide and checklist for patient safety

As the patient population with deep brain stimulators grows, medical personnel need to be comfortable managing these patients because they will likely encounter them in practice. Caring for a patient with a deep brain stimulator during surgery or a procedure requires technical knowledge of the device and its possible interactions in order to take the correct precautionary measures. Here we discuss the key issues and questions that should be covered in every preanesthetic evaluation visit of a patient with a deep brain stimulator along with an evaluation checklist.

Implantable Devices: Assessment and Perioperative Management

Technology is the prominent feature of the twenty-first century, including in medicine. There are very few organs that cannot be stimulated, shocked, or infused. With more and more implantable devices being approved for clinical use, anesthesiologists have to regularly take care of patients who have these devices. An understanding of the devices, the associated comorbidities, and the perioperative risks is crucial for safe management of these patients. Cardiac devices are discussed in some detail; neurostimulators and other implantable devices are briefly described. The principles of assessment and management are similar for all patients with implanted devices.

Practical considerations and nuances in anesthesia for patients undergoing deep brain stimulation implantation surgery

The field of functional neurosurgery has expanded in last decade to include newer indications, new devices, and new methods. This advancement has challenged anesthesia providers to adapt to these new requirements. This review aims to discuss the nuances and practical issues that are faced while administering anesthesia for deep brain stimulation surgery.

Anaesthetic management of a patient with deep brain stimulation implant for radical nephrectomy

A 63-year-old man with severe Parkinson's disease (PD) who had been implanted with deep brain stimulators into both sides underwent radical nephrectomy under general anaesthesia with standard monitoring. Deep brain stimulation (DBS) is an alternative and effective treatment option for severe and refractory PD and other illnesses such as essential tremor and intractable epilepsy. Anaesthesia in the patients with implanted neurostimulator requires special consideration because of the interaction between neurostimulator and the diathermy. The diathermy can damage the brain tissue at the site of electrode. There are no standard guidelines for the anaesthetic management of a patient with DBS electrode in situ posted for surgery.

Preservation of microelectrode recordings with non-GABAergic drugs during deep brain stimulator placement in children

OBJECT

Deep brain stimulation (DBS) has become accepted therapy for intractable dystonia and other movement disorders. The accurate placement of DBS electrodes into the globus pallidus internus is assisted by unimpaired microelectrode recordings (MERs). Many anesthetic and sedative drugs interfere with MERs, requiring the patient to be awake for target localization and neurological testing during the procedure. In this study, a novel anesthetic technique was investigated in pediatric DBS to preserve MERs.

METHODS

In this paper, the authors describe a sedative/anesthetic technique using ketamine, remifentanil, dexmedetomidine, and nicardipine in 6 pediatric patients, in whom the avoidance of GABAergic stimulating drugs permitted excellent surgical conditions with no detrimental effects on intraoperative MERs. The quality of the MERs, and the frequency of its use in making electrode placement decisions, was reviewed.

RESULTS

All 6 patients had good-quality MERs. The data were of sufficient quality to make a total of 9 trajectory adjustments.

CONCLUSIONS

Microelectrode recordings in pediatric DBS can be preserved with a combination of dexmedetomidine and ketamine, remifentanil, and nicardipine. This preservation of MERs is particularly crucial in electrode placement in children.

[The use of neuromodulation for the treatment of tremor]

BACKGROUND

Tremor may be a disabling disorder and pharmacologic treatment is the first-line therapy for these patients. Nevertheless, this treatment may lead to a satisfactory tremor reduction in only 50% of patients with essential tremor. Thalamotomy was the treatment of choice for tremor refractory to medical therapy until deep brain stimulation (DBS) of the ventral intermedius nucleus (Vim) of the thalamus has started being used. Nowadays, thalamotomy is rarely performed.

METHODS

This article is a non-systematic review of the indications, results, programming parameters and surgical technique of DBS of the Vim for the treatment of tremor.

RESULTS

In spite of the fact that it is possible to achieve similar clinical results using thalamotomy or DBS of the Vim, the former causes more adverse effects than the latter. Furthermore, DBS can be used bilaterally, whereas thalamotomy has a high risk of causing disartria when it is performed in both sides. DBS of the Vim achieved an adequate tremor improvement in several series of patients with tremor caused by essential tremor, Parkinson's disease or multiple sclerosis. Besides the Vim, there are other targets, which are being used by some authors, such as the zona incerta and the prelemniscal radiations.

CONCLUSION

DBS of the Vim is a useful treatment for disabling tremor refractory to medical therapy. It is essential to carry out an accurate patient selection as well as to use a proper surgical technique. The best stereotactic target for tremor is still unknown, although the Vim is the most used one.

Anaesthetic management of shoulder arthroscopic repair in Parkinson's disease with deep brain stimulator

We describe the anaesthetic management of arthroscopic repair for complete rotator cuff tear of shoulder in a 59-year-old female with Parkinson's disease (PD) with deep brain stimulator (DBS) using a combination of general anaesthesia with interscalene approach to brachial plexus block. The DBS consists of implanted electrodes in the brain connected to the implantable pulse generator (IPG) normally placed in the anterior chest wall subcutaneously. It can be programmed externally from a hand-held device placed directly over the battery stimulator unit. In our patient, IPG with its leads was located in close vicinity of the operative site with potential for DBS malfunction. Implications of DBS in a patient with PD for shoulder arthroscopy for anaesthesiologist are discussed along with a brief review of DBS.

Neuronal Entropy Depends on the Level of Alertness in the Parkinsonian Globus Pallidus in vivo

A new working hypothesis of Parkinson's disease (PD) proposes to focus on the central role of entropy increase in the basal ganglia (BG) in movement disorders. The conditions necessary for entropy increase in vivo are, however, still not fully described. We recorded the activity of single globus pallidus pars interna neurons during the transition from deep anesthesia to full alertness in relaxed, head-restrained, control, and parkinsonian (6-hydroxydopamine-lesioned group-lesioned) rats. We found that during awakening from anesthesia, the variation of neuronal entropy was significantly higher in the parkinsonian than in the control group. This implies in our view that in PD the entropy of the output neurons of the BG varies dynamically with the input to the network, which is determined by the level of alertness. Therefore, entropy needs to be interpreted as a dynamic, emergent property that characterizes the global state of the BG neuronal network, rather than a static property of parkinsonian neurons themselves. Within the framework of the "entropy hypothesis," this implies the presence of a pathological feedback loop in the parkinsonian BG, where increasing the network input results in a further increase of neuronal entropy and a worsening of akinesia.

[Anesthesiological aspects of deep brain stimulation : special features of implementation and dealing with brain pacemaker carriers]

Deep brain stimulation (DBS) provides a very effective treatment for a number of neurological diseases including Parkinson's disease, movement disorders and epilepsy. In DBS microelectrodes are positioned in defined cerebral target areas and connected to a pacemaker. It is most often performed as an awake craniotomy with intraoperative testing. Various anesthesiological regimes are used to protect the patient from surgical stress on the one hand and to achieve ideal test conditions on the other. They include local anesthesia or scalp blocks, intermittent general anesthesia or analgosedation with or without airway protection; however, anesthetic agents interfere with hemodynamic stability and ventilation, with vigilance and cooperation and in addition with the symptoms and microelectrode recording. Guidance and communication have a pivotal impact on patient needs for pharmacological interventions. With increasing numbers of DBS procedures, anesthesiologists are more often faced with patients carrying brain pacemakers. For anesthesia the characteristics of the disease as well as the respective long-term medication have to be considered. In addition, the rules for handling patients with pacemakers need to be followed to avoid both dysfunction of the generator and tissue damage due to overheating of the electrodes.

Continuous perioperative apomorphine in deep brain stimulation surgery for Parkinson's disease

BACKGROUND

Patients with Parkinson's disease (PD) deprived of dopaminergic medication to facilitate awake testing during the deep brain stimulation (DBS) procedure are at increased risk of neurologic deterioration.. The aim of this survey was to demonstrate the safety of subcutaneous apomorphine treatment for reducing surgery-related neurologic deterioration in patients undergoing DBS surgery for PD.

METHODS

Ninety-two patients who underwent DBS surgery for PD between 11/2007 and 10/2011 in our department were retrospectively analyzed for this survey. Demographic data, apomorphine dosage, side-effects and need of ICU/IMC stay were collected and analyzed.

RESULTS

Seventy-two out of 92 patients (78.3%) received apomorphine treatment; main reason for omission of treatment was intolerable nausea (16/92, 17.3%). Apomorphine treatment was well tolerated and the most common side effect was nodular panniculitis. No severe complications were observed. No patient required ICU/IMC stay related to dopaminergic deprivation.

CONCLUSIONS

Perioperative withdrawal of dopaminergic medication in PD patients leads to an increased risk of neurologic and respiratory deterioration during DBS procedures. These complications can likely be tempered using perioperative subcutaneous apomorphine as a substitute. Our 5-year experience indicates a reduction in postoperative neurologic deterioration and ICU/IMC stay need. We consider perioperative apomorphine safe during DBS surgery for PD.

Implantation of a cardiac resynchronization therapy defibrillator in a patient with bilateral deep brain stimulator: feasibility and technique

Uncommonly, a patient with a NeuroStimulator Device (NSD) for a neurologic indication requires a cardiovascular implantable electronic device (CIED) for a cardiac indication. Typically in those with a unilateral pectoral NSD, the contralateral pectoral space is used for CIED implantation; however, in very rare occasions the patient has bilateral pectoral NSDs which makes subsequent implantation of a CIED challenging both because of placement and device interaction. Herein, we introduce the case of a 68-year-old gentleman with bilateral pectoral deep brain stimulators for Parkinsonism who received cardiac resynchronization therapy-defibrillator (CRT-D) for advanced heart failure. The CRT-D generator was implanted in the abdomen and the CRT-D leads were placed through a minimally invasive epicardial approach. Both devices were tested without any evidence of device interaction.

Anesthetic considerations for awake craniotomy for epilepsy and functional neurosurgery

The two most common neurosurgical procedures that call for an awake patient include epilepsy surgery and functional neurosurgery. Monitoring patients in the awake state allows more aggressive resection of epileptogenic foci in functionally important brain regions. Careful patient selection and preparation combined with attentive monitoring and anticipation of events are fundamental to a smooth awake procedure. Current pharmacologic agents and techniques at the neuroanesthesiologist's disposal facilitate an increasing number of procedures performed in awake patients.

The modified ampullar approach for vestibular implant surgery: feasibility and its first application in a human with a long-term vestibular loss

Objective: To assess, for the first time in a human with a long-term vestibular loss, a modified approach to the ampullae and the feasibility of evoking a VOR by ampullar stimulation. Materials and methods: Peroperative stimulation of the ampullae, using the ampullar approach, was performed under full anesthesia during cochlear implantation in a 21-year-old female patient, who had experienced bilateral vestibular areflexia and sensorineural hearing loss for almost 20 years. Results: The modified ampullar approach was performed successfully with as minimally invasive surgery as possible. Ampullar stimulation evoked eye movements containing vectors congruent with the stimulated canal. As expected, the preliminary electrophysiological data were influenced by the general anesthesia, which resulted in current spread and reduced maximum amplitudes of eye movement. Nevertheless, they confirm the feasibility of ampullar stimulation. Conclusion: The modified ampullar approach provides safe access to the ampullae using as minimally invasive surgery as possible. For the first time in a human with long-term bilateral vestibular areflexia, it is shown that the VOR can be evoked by ampullar stimulation, even when there has been no vestibular function for almost 20 years. This approach should be considered in vestibular surgery, as it provides safe access to one of the most favorable stimulus locations for development of a vestibular implant.