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

Awake versus Asleep Anesthesia in Deep Brain Stimulation Surgery for Parkinson's Disease: A Systematic Review and Meta-Analysis

INTRODUCTION

Deep brain stimulation (DBS) is a well-established surgical therapy for patients with Parkinsons' Disease (PD). Traditionally, DBS surgery for PD is performed under local anesthesia, whereby the patient is awake to facilitate intraoperative neurophysiological confirmation of the intended target using microelectrode recordings. General anesthesia allows for improved patient comfort without sacrificing anatomic precision and clinical outcomes.

METHODS

We performed a systemic review and meta-analysis on patients undergoing DBS for PD. Published randomized controlled trials, prospective and retrospective studies, and case series which compared asleep and awake techniques for patients undergoing DBS for PD were included. A total of 19 studies and 1,900 patients were included in the analysis.

RESULTS

We analyzed the (i) clinical effectiveness - postoperative UPDRS III score, levodopa equivalent daily doses and DBS stimulation requirements. (ii) Surgical and anesthesia related complications, number of lead insertions and operative time (iii) patient's quality of life, mood and cognitive measures using PDQ-39, MDRS, and MMSE scores. There was no significant difference in results between the awake and asleep groups, other than for operative time, for which there was significant heterogeneity.

CONCLUSION

With the advent of newer technology, there is likely to have narrowing differences in outcomes between awake or asleep DBS. What would therefore be more important would be to consider the patient's comfort and clinical status as well as the operative team's familiarity with the procedure to ensure seamless transition and care.

Dexmedetomidine depresses neuronal activity in the subthalamic nucleus during deep brain stimulation electrode implantation surgery

Background

Micro-electrode recordings are often necessary during electrode implantation for deep brain stimulation of the subthalamic nucleus. Dexmedetomidine may be a useful sedative for these procedures, but there is limited information regarding its effect on neural activity in the subthalamic nucleus and on micro-electrode recording quality.

Methods

We recorded neural activity in five patients undergoing deep brain stimulation implantation to the subthalamic nucleus. Activity was recorded after subthalamic nucleus identification while patients received dexmedetomidine sedation (loading - 1 μg kg-1 over 10-15 min, maintenance - 0.7 μg kg-1 h-1). We compared the root-mean square (RMS) and beta band (13-30 Hz) oscillation power of multi-unit activity recorded by microelectrode before, during and after recovery from dexmedetomidine sedation. RMS was normalised to values recorded in the white matter.

Results

Multi-unit activity decreased during sedation in all five patients. Mean normalised RMS decreased from 2.8 (1.5) to 1.6 (1.1) during sedation (43% drop, p = 0.056). Beta band power dropped by 48.4%, but this was not significant (p = 0.15). Normalised RMS values failed to return to baseline levels during the time allocated for the study (30 min).

Conclusions

In this small sample, we demonstrate that dexmedetomidine decreases neuronal firing in the subthalamic nucleus as expressed in the RMS of the multi-unit activity. As multi-unit activity is a factor in determining the subthalamic nucleus borders during micro-electrode recordings, dexmedetomidine should be used with caution for sedation during these procedures.

Clinical trial number

NCT01721460.

Asleep DBS under ketamine sedation: Proof of concept

BACKGROUND

Deep brain stimulation (DBS) is commonly and safely performed for selective Parkinson's disease patients. Many centers perform DBS lead positioning exclusively under local anesthesia, to optimize brain microelectrode recordings (MER) and testing of stimulation-related therapeutic and side effects. These measures enable physiological identification of the DBS borders and subdomains based on electrophysiological properties like firing rates and patterns, intra-operative evaluation of therapeutic window, and improvement of lead placement accuracy. Nevertheless, due to the challenges of awake surgery, some centers use sedation or general anesthesia, despite the distortion of discharge properties and interference with clinical testing, resulting in potential impact on surgical outcomes. Thus, there is a need for a novel anesthesia regimen that enables sedation without compromising intra-operative monitoring.

OBJECTIVE

This open-label study investigates the use of low-dose ketamine for conscious sedation during microelectrode recordings and lead positioning in subthalamic nucleus (STN) DBS for Parkinson's disease patients.

METHODS

Three anesthetic regimens were retrospectively compared in 38 surgeries (74 MER trajectories, 5962 recording sites) across three DBS centers: 1) Interleaved propofol-ketamine (PK), 2) Interleaved propofol-awake (PA), and 3) Fully awake (AA).

RESULTS

All anesthesia regimens achieved satisfactory MER. Detection of STN borders and subdomains by expert electrophysiologist was similar between the groups. Electrophysiological signature of the STN under ketamine was not inferior to either control group. All patients completed stimulation testing.

CONCLUSIONS

This study supports a low-dose ketamine anesthesia regimen for DBS which allows microelectrode recordings and stimulation testing that are not inferior to those conducted under awake and propofol-awake regimens and may optimize patient experience. A prospective double-blind study that would also compare patients' satisfaction level and clinical outcome should be performed to confirm these findings.

Delayed Recovery After Deep Brain Stimulation Surgery for Parkinson's Disease Under General Anesthesia-Cases Report

Objective

Parkinson's disease (PD) is a neurodegenerative syndrome, and deep-brain stimulation (DBS) is an effective therapy for carefully screened patients with PD. However, delayed recovery after anesthesia, which occurs after taking prolonged general anesthesia for such patients, has been reported less frequently in literature. This report explores the possible causes of postoperative awakening delay in patients undergoing DBS surgery due to general anesthesia and provides a reference for anesthesia management of similar operations in the future.

Case Presentation

Three patients with PD elective underwent DBS surgery. The first patients demonstrated walking disability, gait deficits, unstable posture, limb stiffness, and imbalance. The second demonstrated left limb static tremor, stiffness, and bradykinesia. The third demonstrated bradykinesia, rigidity, walking deficits, and decreased facial expression. These included two males and one female with a mean patient age of 60.7 ± 6.7year, weight of 63.7 ± 11 kg, the height of 163.3 ± 7.6 cm, and preoperative American Society of Anesthesiology rating of 2.3 ± 0.6. The preoperative Glasgow Coma Scale mean score was 15. All patients completed the operation under general anesthesia (the mean anesthesia time was 5.3 ± 1.1 h). The mean operation time was 252 ± 60 min. The mean bleeding volume was 50 ml, and the urine volume was 867 ± 569 ml. However, all the patients showed unconsciousness after 95 ± 22 min after stopping the anesthetic, and the respiratory function was in good condition, but they could not cooperate with anesthesiologists and had no response to the anesthesiologist's instructions. The mean hospital stay was 17 ± 7 days. All patients were discharged uneventfully. The average number of days patients followed up postoperatively was 171 ± 28.5 days. Motor and speech were improved significantly postoperatively in three patients compared with preoperatively. Taking anti-Parkinson medication was markedly reduced. There were no complications during postoperative follow-up.

Conclusions

To prevent delayed recovery occurring after DBS surgery in Parkinson's disease, it is recommended to take scalp nerve block + general anesthesia to complete the procedure while avoiding general anesthesia.

Long-Term Outcomes of Deep Brain Stimulation for Pediatric Dystonia

BACKGROUND

Deep brain stimulation (DBS) has been utilized for over two decades to treat medication-refractory dystonia in children. Short-term benefit has been demonstrated for inherited, isolated, and idiopathic cases, with less efficacy in heredodegenerative and acquired dystonia. The ongoing publication of long-term outcomes warrants a critical assessment of available information as pediatric patients are expected to live most of their lives with these implants.

SUMMARY

We performed a review of the literature for data describing motor and neuropsychiatric outcomes, in addition to complications, 5 or more years after DBS placement in patients undergoing DBS surgery for dystonia at an age younger than 21. We identified 20 articles including individual data on long-term motor outcomes after DBS for a total of 78 patients. In addition, we found five articles reporting long-term outcomes after DBS in 9 patients with status dystonicus. Most patients were implanted within the globus pallidus internus, with only a few cases targeting the subthalamic nucleus and ventrolateral posterior nucleus of the thalamus. The average follow-up was 8.5 years, with a range of up to 22 years. Long-term outcomes showed a sustained motor benefit, with median Burke-Fahn-Marsden dystonia rating score improvement ranging from 2.5% to 93.2% in different dystonia subtypes. Patients with inherited, isolated, and idiopathic dystonias had greater improvement than those with heredodegenerative and acquired dystonias. Sustained improvements in quality of life were also reported, without the development of significant cognitive or psychiatric comorbidities. Late adverse events tended to be hardware-related, with minimal stimulation-induced effects.

KEY MESSAGES

While data regarding long-term outcomes is somewhat limited, particularly with regards to neuropsychiatric outcomes and adverse events, improvement in motor outcomes appears to be preserved more than 5 years after DBS placement.

Anesthesia for deep brain stimulation: an update

PURPOSE OF REVIEW

Deep brain stimulation (DBS) is a rapidly expanding surgical modality for the treatment of patients with movement disorders. Its ability to be adjusted, titrated, and optimized over time has given it a significant advantage over traditional more invasive surgical procedures. Therefore, the success and popularity of this procedure have led to the discovery of new indications and therapeutic targets as well as advances in surgical techniques. The aim of this review is to highlight the important updates in DBS surgery and to exam the anesthesiologist's role in providing optimal clinical management.

RECENT FINDINGS

New therapeutic indications have a significant implication on perioperative anesthesia management. In addition, new technologies like frameless stereotaxy and intraoperative magnetic resonance imaging to guide electrode placement have altered the need for intraoperative neurophysiological monitoring and hence increased the use of general anesthesia. With an expanding number of patients undergoing DBS implantation, patients with preexisting DBS increasingly require anesthesia for unrelated surgery and the anesthesiologist must be aware of the considerations for perioperative management of these devices and potential complications.

SUMMARY

DBS will continue to grow and evolve requiring adaptation and modification to the anesthetic management of these patients.

Toward asleep DBS: cortico-basal ganglia spectral and coherence activity during interleaved propofol/ketamine sedation mimics NREM/REM sleep activity

Deep brain stimulation (DBS) is currently a standard procedure for advanced Parkinson's disease. Many centers employ awake physiological navigation and stimulation assessment to optimize DBS localization and outcome. To enable DBS under sedation, asleep DBS, we characterized the cortico-basal ganglia neuronal network of two nonhuman primates under propofol, ketamine, and interleaved propofol-ketamine (IPK) sedation. Further, we compared these sedation states in the healthy and Parkinsonian condition to those of healthy sleep. Ketamine increases high-frequency power and synchronization while propofol increases low-frequency power and synchronization in polysomnography and neuronal activity recordings. Thus, ketamine does not mask the low-frequency oscillations used for physiological navigation toward the basal ganglia DBS targets. The brain spectral state under ketamine and propofol mimicked rapid eye movement (REM) and Non-REM (NREM) sleep activity, respectively, and the IPK protocol resembles the NREM-REM sleep cycle. These promising results are a meaningful step toward asleep DBS with nondistorted physiological navigation.

Deep Brain Stimulation of the Globus Pallidus Internus for Secondary Dystonia: Clinical Cases and Systematic Review of the Literature Regarding the Effectiveness of Globus Pallidus Internus versus Subthalamic Nucleus

OBJECTIVE

Deep brain stimulation (DBS) is a frequently applied therapy in primary dystonia. For secondary dystonia, the effects can be less favorable. We share our long-term findings in 9 patients with severe secondary dystonia and discuss these findings in the light of the literature.

METHODS

Patients who had undergone globus pallidus internus (GPi)-DBS for secondary dystonia were included. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores, clinical improvement rates, follow-up periods, stimulation parameters and the need for internal pulse generator replacements were analyzed. The PubMed and Google Scholar databases were searched for articles describing GPi-DBS and subthalamic nucleus (STN)-DBS only for secondary dystonia cases. Keywords were "dystonia," "deep brain stimulation," "GPi," "dystonia," "deep brain stimulation," and "STN."

RESULTS

A total of 9 secondary dystonia patients (5 male, 4 female) had undergone GPi-DBS with microelectrode recording in our units. The mean follow-up period was 29 months. The average BFMDRS score was 58.2 before the surgery, whereas the mean value was 36.5 at the last follow-up of the patients (mean improvement, 39%; minimum, 9%; maximum, 63%). In the literature review, we identified 264 GPi-DBS cases (mean follow-up, 19 months) in 72 different articles about secondary dystonia. The mean BFMDRS improvement rate was 52%. In 146 secondary dystonia cases, reported in 19 articles, STN-DBS was performed. The average follow-up period was 20 months and the improvement in BFMDRS score was 66%.

CONCLUSIONS

Although GPi-DBS has favorable long-term efficacy and safety in the treatment of patients with secondary dystonia, STN seems a promising target for stimulation in patients with secondary dystonia. Further studies including a large number of patients, longer follow-up periods, and more homogenous patients are necessary to establish the optimal target for DBS in the management of secondary dystonias.

The role of dexmedetomidine in neurosurgery

Dexmedetomidine can be used for sedation and analgesia and has been approved for this use by the European Medicines Agency since 2017. It causes an arousable state of sedation, which is beneficial during neurosurgical procedures that require the patient to cooperate with neurological tests (i.e. tumor surgery or implantation of deep brain stimulators). During procedures where monitoring of somatosensory evoked potentials and/or motor evoked potentials is required, dexmedetomidine can be used as an adjunct to general anesthesia with GABAergic drugs to decrease the dose of the latter when these drugs impair the monitoring signals. The use of dexmedetomidine has also been associated with neuroprotective effects and a decreased incidence of delirium, but studies confirming these effects in the peri-operative (neuro-)surgical setting are lacking. Although dexmedetomidine does not cause respiratory depression, its hemodynamic effects are complex and careful patient selection, choice of dose, and monitoring must be performed.

The Effects of Intraoperative Sedation on Surgical Outcomes of Deep Brain Stimulation Surgery

BACKGROUND

Intraoperative sedation is often used to facilitate deep brain stimulation (DBS) surgery; however, these sedative agents also suppress microelectrode recordings (MER). To date, there have been no studies that have examined the effects of differing sedatives on surgical outcomes and the success of DBS surgery.

METHODS

We performed a retrospective study to evaluate the effect of differing sedative agents on postoperative surgical outcomes at 6 months in parkinsonian adult patients who underwent DBS surgery, from January 2004 through December 2014, at one academic center. Surgical outcomes of DBS were evaluated using a simplified Unified Parkinson Diseases Rating Score-III and levodopa dose equivalent reduction at baseline and 6 months postoperatively.

RESULTS

We analyzed data from 121 of 124 consecutive parkinsonian patients. Propofol, dexmedetomidine, remifentanil, and midazolam were used individually or in combination. All sedatives were routinely discontinued 20 to 30 minutes before MER, in accordance with our institutional protocol. We found no statistically significant association between the use of individual agent or combination of sedative agents and surgical outcomes at 6 months, the success of DBS, duration of MER, duration of stage 1 procedure, and perioperative complications.

CONCLUSIONS

Our study showed that the choice of sedative agent was not associated with poor surgical outcomes after DBS surgery using MER and macrostimulation techniques in parkinsonian patients.

A comparative historical and demographic study of the neuromodulation management techniques of deep brain stimulation for dystonia and cochlear implantation for sensorineural deafness in children

Cochlear implants for sensorineural deafness in children is one of the most successful neuromodulation techniques known to relieve early chronic neurodisability, improving activity and participation. In 2012 there were 324,000 recipients of cochlear implants globally.

AIM

To compare cochlear implant (CI) neuromodulation with deep brain stimulation (DBS) for dystonia in childhood and explore relations between age and duration of symptoms at implantation and outcome.

METHODS

Comparison of published annual UK CI figures for 1985-2009 with a retrospective cohort of the first 9 years of DBS for dystonia in children at a single-site Functional Neurosurgery unit from 2006 to 14.

RESULTS

From 2006 to 14, DBS neuromodulation of childhood dystonia increased by a factor of 3.8 to a total of 126 cases over the first 9 years, similar to the growth in cochlear implants which increased by a factor of 4.1 over a similar period in the 1980s rising to 527 children in 2009. The CI saw a dramatic shift in practice from implantation at >5 years of age at the start of the programme towards earlier implantation by the mid-1990s. Best language results were seen for implantation <5 years of age and duration of cochlear neuromodulation >4 years, hence implantation <1 year of age, indicating that severely deaf, pre-lingual children could benefit from cochlear neuromodulation if implanted early. Similar to initial CI use, the majority of children receiving DBS for dystonia in the first 9 years were 5-15 years of age, when the proportion of life lived with dystonia exceeds 90% thus limiting benefits.

CONCLUSION

Early DBS neuromodulation for acquired motor disorders should be explored to maximise the benefits of dystonia reduction in a period of maximal developmental plasticity before the onset of disability. Learning from cochlear implantation, DBS can become an accepted management option in children under the age of 5 years who have a reduced proportion of life lived with dystonia, and not viewed as a last resort reserved for only the most severe cases where benefits may be at their most limited.

Anaesthesia for deep brain stimulation: a review

PURPOSE OF REVIEW

Deep brain stimulation (DBS) is a well tolerated and efficacious surgical treatment for movement disorders, chronic pain, psychiatric disorder, and a growing number of neurological disorders. Given that the brain targets are deep and small, accurate electrode placement is commonly accomplished by utilizing frame-based systems. DBS electrode placement is confirmed by microlectrode recordings and macrostimulation to optimize and verify target placement. With a reliance on electrophysiology, proper anaesthetic management is paramount to balance patient comfort without interfering with neurophysiology.

RECENT FINDINGS

To achieve optimal pain control, generous amounts of local anaesthesia are instilled into the planned incision. During the opening and closing states, conscious sedation is the prevailing method of anaesthesia. The preferred agents are dexmedetomidine, propofol, and remifentanil, as they affect neurocognitive testing the least, and shorter acting. All the agents are turned off 15-30 min prior to microelectrode recording. Dexmedetomidine has gained popularity in DBS procedures, but has some considerations at higher doses. The addition of ketamine is helpful for pediatric cases.

SUMMARY

DBS is a robust surgical treatment for a variety of neurological disorders. Appropriate anaesthetic agents that achieve patient comfort without interfering with electrophysiology are paramount.

Anesthesia for deep brain stimulation in traumatic brain injury-induced hemidystonia

Deep brain stimulation in an awake patient presents several unique challenges to the anesthesiologist. It is important to understand the various stages of the procedure and the complexities of anesthetic management in order to have a successful surgical outcome and provide a safe environment for the patient.