[Scalp blocks. A useful technique for neurosurgery, dermatology, plastic surgery and pain therapy]

What is the effect of benzodiazepines on deep brain activity? A study in pediatric patients with dystonia

Introduction

Benzodiazepines (BDZs) are commonly used to treat the symptoms of movement disorders; however, deep brain stimulation (DBS) has become a popular treatment for these disorders. Previous studies have investigated the effects of BDZ on cortical activity, no data are currently available on their effects on deep brain regions, nor on these regions' responses to DBS. How the BDZ affects the thalamus and basal ganglia in dystonia patients remains unknown.

Methods

DBS recordings were performed in ventral oralis anterior/posterior (VoaVop), ventral intermediate (VIM) and ventral anterior (VA) thalamic subnuclei, as well as globus pallidus interna (GPi) and subthalamic nucleus (STN). Evoked potentials (EP) and frequency domain analysis were performed to determine the BDZ effect on neural activities compared to the control condition (off-BDZ). Three male pediatric patients with dystonia treated with BDZ and undergoing depth electrode evaluation for clinical targeting were recruited for the study. Stimulation was administered at 25 and 55 Hz frequencies and recordings were simultaneously gathered through pairs of externalized stereoelectroencephalography (sEEG) electrodes. EP amplitude and the effect of stimulation on the frequency spectrum of activity were compared at baseline and following clinical administration of BDZ.

Results

Frequency analysis showed consistent reductions in activity during BDZ treatment in all studied brain regions for all patients. Evoked potential (EP) analysis showed increased subthalamic nucleus (STN) EP amplitude and decreased ventral intermediate (VIM) and STN EP amplitude during BDZ treatment.

Interpretation

BDZs reduce thalamic and basal ganglia activity in multiple regions and alter the efficacy of transmission between these regions. While the mechanism is unknown our results confirm the known widespread effects of this class of medications and identify specific areas within the motor system that are directly affected.

Scalp block for postoperative pain after craniotomy: A meta-analysis of randomized control trials

Background

Postoperative pain after craniotomy is an important clinical concern because it might lead to brain hyperemia and elevated intracranial pressure. Considering the side effects of opioid, several studies have been conducted to investigate the effect of local anesthetics, especially the scalp block, on postoperative pain. However, the strength of evidence supporting this practice for postoperative pain after craniotomy was unclear and the best occasion of scalp block was also not identified. Therefore, we conducted a meta-analysis to evaluate the efficacy, safety, and the best occasion of scalp block for postoperative pain after craniotomy.

Methods

PubMed, Embase, and the Cochrane Library databases from database inception to October 10, 2021 were searched for all randomized controlled trials evaluating the effect of scalp block on postoperative pain after craniotomy. Data were assessed by StataMP 16 software.

Results

A total of 12 studies were included. A random-effect model was used to analyze all data. Patients under scalp block earned fewer scores than the non-scalp block group in visual analogue scale at the very early period (MD = −1.97, 95% CI = −3.07 to −0.88), early period (MD = −1.84, 95% CI = −2.95 to −0.73) and intermediate period (MD = −1.16, 95% CI = −1.84 to −0.49). Scalp block could also significantly prolong the time of the first request of rescue analgesia and reduce the use of additional analgesics without a significant difference in the incidence of complications. Subgroup analysis showed there was no significant difference in analgesia effect between pre-incision scalp block and post-incision scalp block in all periods.

Conclusion

Scalp block could lead to lower pain intensity scores, more time of the first request of rescue analgesia, and fewer analgesic drugs applied in the first 12 h after craniotomy. There was no significant difference between pre-incision and post-incision scalp block in the occurrence and severity of postoperative pain.

Local anesthetics for brain tumor resection: current perspectives

This review summarizes the added value of local anesthetics in patients undergoing craniotomy for brain tumor resection, which is a procedure that is carried out frequently in neurosurgical practice. The procedure can be carried out under general anesthesia, sedation with local anesthesia or under local anesthesia only. Literature shows a large variation in the postoperative pain intensity ranging from no postoperative analgesia requirement in two-thirds of the patients up to a rate of 96% of the patients suffering from severe postoperative pain. The only identified causative factor predicting higher postoperative pain scores is infratentorial surgery. Postoperative analgesia can be achieved with multimodal pain management where local anesthesia is associated with lower postoperative pain intensity, reduction in opioid requirement and prevention of development of chronic pain. In awake craniotomy patients, sufficient local anesthesia is a cornerstone of the procedure. An awake craniotomy and brain tumor resection can be carried out completely under local anesthesia only. However, the use of sedative drugs is common to improve patient comfort during craniotomy and closure. Local anesthesia for craniotomy can be performed by directly blocking the six different nerves that provide the sensory innervation of the scalp, or by local infiltration of the surgical site and the placement of the pins of the Mayfield clamp. Direct nerve block has potential complications and pitfalls and is technically more challenging, but mostly requires lower total doses of the local anesthetics than the doses required in surgical-site infiltration. Due to a lack of comparative studies, there is no evidence showing superiority of one technique versus the other. Besides the use of other local anesthetics for analgesia, intravenous lidocaine administration has proven to be a safe and effective method in the prevention of coughing during emergence from general anesthesia and extubation, which is especially appreciated after brain tumor resection.

Deep Brain Stimulation Surgery without Sedation

<b><i>Background:</i></b> Sedatives and opioids used during deep brain stimulation (DBS) surgery interfere with optimal target localization and add to side effects and risks, and thus should be minimized. <b><i>Objective:</i></b> To retrospectively test the actual need for sedatives and opioids when cranial nerve blocks and specific therapeutic communication are applied. <b><i>Methods:</i></b> In a case series, 64 consecutive patients treated with a strong rapport, constant contact, non-verbal communication and hypnotic suggestions, such as dissociation to a “safe place,” reframing of disturbing noises and self-confirmation, were compared to 22 preceding patients under standard general anaesthesia or conscious sedation. <b><i>Results:</i></b> With introduction of the protocol the need for sedation dropped from 100% in the control group to 5%, and from a mean dose of 444 mg to 40 mg in 3 patients. Remifentanil originally used in 100% of the patients in an average dose of 813 µg was reduced in the study group to 104 µg in 31% of patients. There were no haemodynamic reactions indicative of stress during incision, trepanation, electrode insertion and closure. <b><i>Conclusion:</i></b> With adequate therapeutic communication, patients do not require sedation and no or only low-dose opioid treatment during DBS surgery, leaving patients fully awake and competent during surgery and testing.

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.

Anesthesiologic regimen and intraoperative delirium in deep brain stimulation surgery for Parkinson's disease

BACKGROUND

In many centers the standard anesthesiological care for deep brain stimulation (DBS) surgery in Parkinson's disease patients is an asleep-awake-asleep procedure. However, sedative drugs and anesthetics can compromise ventilation and hemodynamic stability during the operation and some patients develop a delirious mental state after the initial asleep phase. Further, these drugs interfere with the patient's alertness and cooperativeness, the quality of microelectrode recordings, and the recognition of undesired stimulation effects. In this study, we correlated the incidence of intraoperative delirium with the amount of anesthetics used intraoperatively.

METHODS

The anesthesiologic approach is based on continuous presence and care, avoidance of negative suggestions, use of positive suggestions, and utilization of the patient's own resources. Clinical data from the operations were analyzed retrospectively, the occurrence of intraoperative delirium was extracted from patients' charts. The last 16 patients undergoing the standard conscious sedation procedure (group I) were compared to the first 22 (group II) psychologically-guided patients.

RESULTS

The median amount of propofol decreased from 146 mg (group I) to 0mg (group II), remifentanyl from 0.70 mg to 0.00 mg, respectively (P<0.001 for propofol and remifentanyl). Using the new procedure, 12 of 22 patients (55%) in group II required no anesthetics. Intraoperative delirium was significantly less frequent in group II (P=0.03).

CONCLUSIONS

The occurrence of intraoperative delirium correlates with the amount of intraoperative sedative and anesthetic drugs. Sedation and powerful analgesia are not prerequisites for patients' comfort during awake-DBS-surgery.

[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.

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.

[Neuroanaesthesia. Principles of optimized perioperative management]

Because of the high vulnerability of the brain as a primary target, neuroanaesthesia requires a close look at basic physiological principles and factors of influence during surgery and subsequent intensive care. Anticipatory management is crucial for anaesthesia within the scope of neurosurgical interventions: essential components of anaesthesia management must already be prepared before the surgical procedure. Intracranial compliance and pressure determine the patient's fate; accordingly they have to be assessed correctly and measured continuously. Advanced methods of monitoring allow sophisticated and individually focused treatment thus contributing to patient safety. Only few pharmacologic approaches have been proven with solid evidence, yet some new studies have revealed interesting brain protective effects of pharmacological and/or adjuvant therapeutic measures. For the treatment of intracranial hypertension, osmotherapy is still of the highest value. Decompressive craniotomy seems to have become a promising alternative, although this must be judged to date as a last resort therapy. Perioperative care of patients with complex intracranial pathologies thus needs a close interaction and cooperation between the operation theatre and intensive care units in the sense of continuous track anaesthesia.