Awake craniotomy with dexmedetomidine in pediatric patients

Awake craniotomy in pediatric low-grade glioma: barriers and future directions

INTRODUCTION

The goal of surgical management in pediatric low-grade gliomas (pLGGs) is gross total resection (GTR), as it is considered curative with favorable long-term outcomes. Achieving GTR can be challenging in the setting of eloquent-region gliomas, in which resection may increase risk of neurological deficits. Awake craniotomy (AC) with intraoperative neurofunctional mapping (IONM) offers a promising approach to achieve maximal resection while preserving neurological function. However, its adoption in pediatric cases has been hindered, and barriers to its adoption have not previously been elucidated.

FINDINGS

This review includes two complementary investigations. First, a survey study was conducted querying pediatric neurosurgeons on their perceived barriers to the procedure in children with pLGG. Next, these critical barriers were analyzed in the context of existing literature. These barriers included the lack of standardized IONM techniques for children, inadequate surgical and anesthesia experience, concerns regarding increased complication risks, doubts about children's ability to tolerate the procedure, and perceived non-indications due to alternative monitoring tools.

CONCLUSION

Efforts to overcome these barriers include standardizing IONM protocols, refining anesthesia management, enhancing patient preparation strategies, and challenging entrenched beliefs about pediatric AC. Collaborative interdisciplinary efforts and further studies are needed to establish safety guidelines and broaden the application of AC, ultimately improving outcomes for children with pLGG.

Awake Craniotomy in Pediatric Patients: A Meta-analysis of Operative Outcomes

BACKGROUND

Awake craniotomy allows neurosurgeons to make critical decisions when operating in eloquent regions of the brain. The phenomenon of "waking up" during surgery is underexplored in pediatric patients, and the operative outcomes following awake craniotomy are not well understood. Correspondingly, the aim of this study was to quantitatively aggregate the contemporary metadata regarding the operative outcomes of awake craniotomy when used in the pediatric setting.

METHODS

Multiple electronic databases from inception to June 2023 were searched following PRISMA guidelines. Respective cohort-level outcomes were then abstracted and pooled by means of meta-analysis utilizing random-effects modeling, and trends evaluated by meta-regression analysis.

RESULTS

There were 4 observational studies that satisfied all selection criteria, describing a total cohort of 57 pediatric patients undergoing awake craniotomy. There were 34 (60%) male patients with a median age of 14 years old, with lesions on the left side in 80% of cases when reported. Meta-analysis demonstrated pooled incidences of intraoperative complication to be 17% (95% CI 4%-37%), the need to convert cases to general anesthesia to be 2% (95% CI 0%-9%), immediate postoperative complication to be 18% (95% CI 6%-33%), and long-term complications to be 6% (95% CI 0%-15%). The most common intraoperative complication reported was seizure. Certainty of these estimates were very low due to limited metadata. Meta-regression did not indicate any trend bias due to study and cohort parameters.

CONCLUSIONS

Multiple studies have demonstrated the feasibility of the awake craniotomy approach in pediatric patients. The risks for intraoperative and postoperative complications are non-zero, with their incidences trending towards incidences seen in the adult demographic. It is likely formal neuropsychologic preparation and follow-up will increase the candidacy and success of this approach in the future.

Awake Craniotomy Language Mapping in Children With Drug-Resistant Epilepsy due to Focal Cortical Dysplasia

BACKGROUND

Language mapping during awake craniotomy can allow for precise resection of epileptogenic lesions, while reducing the risk of damage to eloquent cortex. There are few reports in the literature of language mapping during awake craniotomy in children with epilepsy. Some centers may avoid awake craniotomy in the pediatric age group due to concerns that children are unable to cooperate with such procedures.

METHODS

We reviewed pediatric patients from our center with drug-resistant focal epilepsy who underwent language mapping during awake craniotomy and subsequent resection of the epileptogenic lesion.

RESULTS

Two patients were identified, both female, aged 17 years and 11 years at the time of surgery. Both patients had frequent and disabling focal seizures despite trials of multiple antiseizure medications. Both patients had resection of their epileptogenic lesions with the aid of intraoperative language mapping; in both cases pathology was consistent with focal cortical dysplasia. Both patients had transient language difficulties in the immediate postoperative period but no deficits at six-month follow-up. Both patients are now seizure-free.

CONCLUSIONS

Awake craniotomy should be considered in pediatric patients with drug-resistant epilepsy in whom the suspected epileptogenic lesion is in close proximity to cortical language areas.

Dexmedetomidine - An emerging option for sedation in neonatal patients

Dexmedetomidine is a sedative agent with limited dosing, safety, and efficacy information in the neonatal population. This comprehensive review describes the available evidence summarizing the use of dexmedetomidine in various neonatal populations. We identified 21 studies and 1 case report supporting the efficacy and short-term safety of DEX in neonates. Reported dosing ranges from 0.5-1.5 mcg/kg/h with or without loading doses. Clinically relevant adverse effects include bradycardia and hypotension. Future studies are needed to determine long-term safety and facilitate clinical applicability.

Language improvement after awake craniotomy in a 12-year-old child: illustrative case

BACKGROUND

Although the standard procedure to treat adult patients with lesions in eloquent brain areas is awake craniotomy with direct electrical stimulation, this procedure is not often used in children because of feasibility concerns. Some studies have shown that the procedure is feasible in children. They reported the postoperative language ability, which was not based on standardized language tests for children. To give an objective overview of preoperative assessment of the language ability of a child before and after this procedure, the authors described the perioperative course, including standardized language tests for children and the awake surgery setting, of a 12-year-old child undergoing awake craniotomy with brain mapping for the indication of cavernoma in the left somatosensory cortex close to the motor cortex.

OBSERVATIONS

The patient performed better on language tests after surgery, showing that his language ability improved. He also cooperated well during the entire perioperative period. His mother was present during the awake surgery, and the patient tolerated the surgery well.

LESSONS

The authors conclude that awake craniotomy is indeed feasible in a child and that it can even result in an improved postoperative language outcome. It is, however, crucial to carefully assess, inform, and monitor the child and their proxies.

Dexmedetomidine Co-Administered with Lidocaine Decreases Nociceptive Responses and Trigeminal Fos Expression without Motor Dysfunction and Hypotension in a Murine Orofacial Formalin Model

Administration of dexmedetomidine significantly induces sedation and anti-nociception in several nociceptive models, but clinical trials are restricted due to adverse side effects, including lethargy, hypotension, and bradycardia. Herein, we investigated whether intraperitoneal inoculation of dexmedetomidine reduced the orofacial nociceptive response and affected motor coordination and blood pressure and examined whether a lower dose of dexmedetomidine in combination with 0.5% lidocaine produced an antinociceptive effect without any adverse side events in a murine model. To perform the experiment, 5% formalin (10 µL) was subcutaneously inoculated into the right upper lip, and the rubbing responses were counted for 45 min. Different doses of dexmedetomidine combined with 0.5% lidocaine were administered 10 and 30 min before formalin injection, respectively. Dexmedetomidine (10 μg/kg) significantly reduced orofacial nociceptive responses during the second phase of the formalin test and decreased the expression of Fos in trigeminal nucleus caudalis (TNC). Besides, a high dose of dexmedetomidine (30 μg/kg) induced lessening physical ability and significantly reduced systolic pressure and heart rate. When 0.5% lidocaine was injected subcutaneously, nociceptive responses were reduced only in the first phase. Interestingly, although a low dose of dexmedetomidine (3 μg/kg) alone did not show an antinociceptive effect, its co-administration with lidocaine significantly reduced the nociceptive response in both phases and decreased TNC Fos expression without motor dysfunction and hypotension. This finding suggests that the combination of a low-dose of systemic dexmedetomidine with lidocaine may be a safe medicinal approach for acute inflammatory pain management in the orofacial region, particularly mucogingival pain.

Intraoperative neurophysiological monitoring in paediatric neurosurgery

Intraoperative neurophysiological monitoring (IONM) is commonly used in various surgical procedures in adults, but with technological and anaesthetic advancements, its use has extended to the paediatric population. The use of IONM in children poses a unique set of challenges considering the anatomical and physiological differences in this group of patients. The use of IONM aids in the localization of neural structures and enables surgeons to preserve the functional neural structures leading to decreased incidence of postoperative neurological deficits and better patient outcomes. In this article, we review the use of IONM in paediatric patients undergoing various spinal and cranial neurosurgical procedures. We discuss the patient characteristics, type of surgeries, and technical and anaesthetic considerations about IONM in this population.

Technical Considerations in Awake Craniotomy with Cortical and Subcortical Motor Mapping in Preadolescents: Pushing the Envelope

INTRODUCTION

Unlike adult gliomas, the utility of combined application of awake anesthesia and intraoperative neurophysiological monitoring (IONM) for maximal safe resection in eloquent region gliomas (ERG) has not been established for pediatric population while it remains unexplored in preadolescents (below 11 years old).

CASE PRESENTATION

We report 2 cases of awake craniotomy with IONM in an 8 and 9 year old for safe maximal resection of ERG. In both the cases, repeated preoperative visits of the operating room was performed to familiarize and educate the children about intraoperative communication, comfortable positioning, and neurological assessment. Under conscious sedation protocol, cortical and subcortical mapping, and electrocorticography, gross total resection was achieved. In both the cases, there were no postoperative neurodeficits or perioperative complications.

CONCLUSION

Our 2 cases illustrate the first instance of successful use of awake IONM for maximal safe resection of ERG in preadolescent age-group. We believe, with proper preoperative planning and careful titration of anesthetics, it is safe and feasible. The blanket notion that preadolescent age-group should be excluded from awake mapping needs to be challenged, rather curated on a case basis.

Awake Craniotomy in a Child: Assessment of Eligibility with a Simulated Theatre Experience

Background

Awake craniotomy is a useful surgical approach to identify and preserve eloquent areas during tumour resection, during surgery for arteriovenous malformation resections and for resective epilepsy surgery. With decreasing age, a child's ability to cooperate and mange an awake craniotomy becomes increasingly relevant. Preoperative screening is essential to identify the child who can undergo the procedure safely. Case Description. A 11-year-old female patient presented with a tumour in her right motor cortex, presumed to be a dysembryoplastic neuroepithelial tumour (DNET). We had concerns regarding the feasibility of performing awake surgery in this patient as psychological testing revealed easy distractibility and an inability to follow commands repetitively. We devised a simulated surgical experience to assess her ability to manage such a procedure. During the simulated theatre experience, attempts were made to replicate the actual theatre experience as closely as possible. The patient was dressed in theatre attire and brought into the theatre on a theatre trolley. She was then transferred onto the theatre bed and positioned in the same manner as she would be for the actual surgery. Her head was placed on a horseshoe headrest, and she was made to lie in a semilateral position, as required for the surgery. A blood pressure cuff, pulse oximeter, nasal cannula with oxygen flow, and calf pumps were applied. She was then draped precisely as she would have been for the procedure. Theatre lighting was set as it would be for the surgical case. The application of the monitoring devices, nasal cannula, and draping was meant not only to prepare her for the procedure but to induce a mild degree of stress such that we could assess the child's coping skills and ability to undergo the procedure. The child performed well throughout the simulated run, and surgery was thus offered. An asleep-awake-asleep technique was planned and employed for surgical removal of the tumour. Cortical and subcortical mapping was used to identify the eloquent tissue. Throughout the procedure, the child was cooperative and anxiety free. Follow-up MRI revealed gross total removal of the lesion.

Conclusion

A simulated theatre experience allowed us to accurately determine that this young patient, despite relative contraindications, was indeed eligible for awake surgery. We will continue to use this technique for all our young patients in assessing their eligibility for these procedures.

Awake brain surgery in children-a single-center experience

INTRODUCTION

Awake brain surgery (ABS) represents a rare surgical procedure in children as age and psychological aspects, which are considered to interfere with its feasibility and psychological outcome and limit its application. Only few pediatric case series have been reported so far, indicating a more complex translation of this surgical approach to children. However, the advances in neuropsychological testing and monitoring may have a substantial impact on ameliorating the eligibility of children undergoing awake procedures. This study addresses the condition of ABS in a pediatric cohort, focusing on its practicability and diversified outcome aspects.

METHODS

We performed a retrospective review and prospective outcome analysis of pediatric patients with CNS lesions undergoing ABS between 2005 and 2018, completed at the University of Lyon, France.

RESULTS

Eighteen children were considered for ABS with respect to the eloquent location of their CNS lesions documented in their pre-operative MRI. Seventeen of them underwent asleep-awake-asleep brain surgery. The cohort included 5 males and 12 females. The median age at surgery was 14.8 years, (range 9.4 to 17.6 years). Intraoperative testing included electrocortical stimulation while pursuing speech or motor activity. Most of the lesions were intrinsic tumors of glial origin. A complete tumor removal was achieved in 11 patients (65%). Post-operative neurological deficits were transiently observed in 2 patients, whereas severe psychological reactions occurred in 1 child. Persistent attention deficits were found in 2 patients. One patient experienced an infectious complication requiring antibiotic treatment. Two patients died during follow-up due to tumor progression. The mean duration of follow up was 22.2 months (range 3.4 to 46.8 months).

CONCLUSIONS

ABS was shown to be beneficial in terms of efficient tumor resection besides simultaneous preservation of neurological functions. Psychological preparation of the families and the children is essential to increase the number and age range of patients, who can benefit from this technique. Neuropsychological testing before and after surgery is essential to determine cognitive outcome, which can be altered in a minority of patients.

Feasibility of awake craniotomy in the pediatric population

BACKGROUND

Awake craniotomy with direct cortical stimulation and mapping is the gold standard for resection of lesions near eloquent brain areas, as it can maximize the extent of resection while minimizing the risk of neurological damage. In contrast to the adult population, only small series of awake craniotomies have been reported in children.

AIMS

The aim of our study is to establish the feasibility of awake craniotomy in the pediatric population.

METHODS

We performed a retrospective observational study of children undergoing a supratentorial awake craniotomy between January 2009 and April 2019 in a pediatric tertiary care center. Our primary outcome was feasibility of awake craniotomy, defined as the ability to complete the procedure without conversion to general anesthesia. Our secondary outcomes were the incidence of serious intraoperative complications and the mapping completion rate.

RESULTS

Thirty procedures were performed in 28 children: 12 females and 16 males. The median age was 14 years (range 7-17). The primary diagnosis was tumor (83.3%), epilepsy (13.3%), and arterio-venous malformation (3.3%). The anesthetic techniques were asleep-awake-asleep (96.7%) and conscious sedation (3.3%), all cases supplemented with scalp block and pin-site infiltration. Awake craniotomy was feasible in 29 cases (96.7%), one patient converted to general anesthesia due to agitation. Serious complications occurred in six patients: agitation (6.7%), seizures (3.3%), increased intracranial pressure (3.3%), respiratory depression (3.3%), and bradycardia (3.3%). All complications were quickly resolved and without major consequences. Cortical mapping was completed in 96.6% cases. New neurological deficits occurred in six patients (20%)-moderate in one case and mild in 5-being all absent at 6 months of follow-up.

CONCLUSION

Awake craniotomy with intraoperative mapping can be successfully performed in children. Adequate patient selection and close cooperation between neurosurgeons, anesthesiologists, neuropsychologists, and neurophysiologists is paramount. Further studies are needed to determine the best anesthetic technique in this population group.

Awake brain surgery in children-review of the literature and state-of-the-art

OBJECTIVE

Awake brain surgery (ABS) is poorly reported in children as it is considered having limited indications due to age and neuropsychological aspects interfering with its feasibility and psychological outcome. The aim of this article is to review the current state-of-the-art of ABS in children and to offer an objective summary of the published literature on diversified outcome aspects of pediatric awake procedures.

METHODS

A literature review was performed using the MEDLINE (PubMed) electronic database applying the following MeSH terms to the keyword search within titles and abstracts: "awake brain surgery children," "awake brain surgery pediatric," "awake craniotomy children," "awake craniotomy pediatric," and "awake surgery children." Of the initial 753 results obtained from these keyword searches, a full text screening of 51 publications was performed, ultimately resulting in 18 eligible articles for this review.

RESULTS

A total of 18 full text articles reporting the results of 50 patients were included in the analysis. Sixteen of the 18 studies were retrospective studies, comprising 7 case series, 9 case reports, and 2 reviews. Eleven studies were conducted from anesthesiological (25 patients) and 7 from neurosurgical (25 patients) departments. Most of the patients underwent ABS for supratentorial lesions (26 patients), followed by epilepsy surgery (16 patients) and deep brain stimulation (DBS) (8 patients). The median age was 15 years (range 8-17 years). Persistent deficits occurred in 6 patients, (12%), corresponding to minor motor palsies (4%) and neuropsychological concerns (8%). An awake procedure was aborted in 2 patients (4%) due to cooperation failure and anxiety, respectively.

CONCLUSIONS

Despite well-documented beneficial aspects, ABS remains mainly limited to adults. This review confirms a reliable tolerability of ABS in selected children; however, recommendations and guidelines for its standardized implementation in this patient group are pending. Recommendations and guidelines may address diagnostic workup and intra-operative handling besides criteria of eligibility, psychological preparation, and coordinated neuropsychological testing in order to routinely offer ABS to children.

Dexmedetomidine: present and future directions

Dexmedetomidine is a potent, highly selective α-2 adrenoceptor agonist, with sedative, analgesic, anxiolytic, sympatholytic, and opioid-sparing properties. Dexmedetomidine induces a unique sedative response, which shows an easy transition from sleep to wakefulness, thus allowing a patient to be cooperative and communicative when stimulated. Dexmedetomidine may produce less delirium than other sedatives or even prevent delirium. The analgesic effect of dexmedetomidine is not strong; however, it can be administered as a useful analgesic adjuvant. As an anesthetic adjuvant, dexmedetomidine decreases the need for opioids, inhalational anesthetics, and intravenous anesthetics. The sympatholytic effect of dexmedetomidine may provide stable hemodynamics during the perioperative period. Dexmedetomidine-induced cooperative sedation with minimal respiratory depression provides safe and acceptable conditions during neurosurgical procedures in awake patients and awake fiberoptic intubation. Despite the lack of pediatric labelling, dexmedetomidine has been widely studied for pediatric use in various applications. Most adverse events associated with dexmedetomidine occur during or shortly after a loading infusion. There are some case reports of dexmedetomidine-related cardiac arrest following severe bradycardia. Some extended applications of dexmedetomidine discussed in this review are promising, but still limited, and further research is required. The pharmacological properties and possible adverse effects of dexmedetomidine should be well understood by the anesthesiologist prior to use. Moreover, it is necessary to select patients carefully and to determine the appropriate dosage of dexmedetomidine to ensure patient safety.

Sedation for Paediatric Stereotactic Radiosurgery: The Dexmedetomidine Experience

Dexmedetomidine is a potent a2 adrenergic agonist, with sedative and analgesic properties which may make it a suitable sedative agent for procedures on paediatric patients. A six-year-old boy required sedation for stereotactic radiosurgical ablation of an arteriovenous malformation on two occasions. Sedation with dexmedetomidine was planned, with increased dosage used on the second occasion. On both occasions dexmedetomidine was inadequate as a sole agent and required supplementation with other agents.

Who Needs Sleep? An Analysis of Patient Tolerance in Awake Craniotomy

BACKGROUND

Awake craniotomy (AC) is generally a safe and effective procedure; however, a small but not insignificant portion of cases are aborted due to patient intolerance of the awake portion of surgery. There is not yet a firm understanding of what characteristics indicate patient tolerance or failure of AC.

METHODS

We retrospectively reviewed a single-surgeon database of patients treated by AC over a 5-year period. Charts were reviewed for demographic, clinical, and operative characteristics, including anesthetic administration during the awake portion of surgery. Statistical analysis was performed to determine which factors predicted patient tolerance or failure.

RESULTS

Our study cohort comprised 120 patients with an average age of 56.0 ± 15.2 years. A majority of patients were male (55.8%). The most common surgical indication was tumor (95.8%), with gliobastoma as the most common diagnosis (43.3%). Male sex predicted surgical tolerance on univariate analysis (P = 0.015). Remifentanil administration was associated with surgical failure on univariate analysis (P = 0.068), and also predicted failure on multivariate analysis (P = 0.030). Preoperative seizure, ketamine administration, and right-sided surgery each predicted patient tolerance, but did not achieve statistical significance. Similarly, respiratory comorbidity was associated with surgical failure, but did not achieve significance.

CONCLUSIONS

AC remains an effective treatment option; the majority of patients tolerate the procedure without issue. Male patients have lower rates of surgical failure, whereas remifentanil administration may increase failure rate.

Awake surgery for hemispheric low-grade gliomas: oncological, functional and methodological differences between pediatric and adult populations

INTRODUCTION

Brain mapping through a direct cortical and subcortical electrical stimulation during an awake craniotomy has gained an increasing popularity as a powerful tool to prevent neurological deficit while increasing extent of resection of hemispheric diffuse low-grade gliomas in adults. However, few case reports or very limited series of awake surgery in children are currently available in the literature.

METHODS

In this paper, we review the oncological and functional differences between pediatric and adult populations, and the methodological specificities that may limit the use of awake mapping in pediatric low-grade glioma surgery.

RESULTS

This could be explained by the fact that pediatric low-grade gliomas have a different epidemiology and biologic behavior in comparison to adults, with pilocytic astrocytomas (WHO grade I glioma) as the most frequent histotype, and with WHO grade II gliomas less prone to anaplastic transformation than their adult counterparts. In addition, aside from the issue of poor collaboration of younger children under 10 years of age, some anatomical and functional peculiarities of children developing brain (cortical and subcortical myelination, maturation of neural networks and of specialized cortical areas) can influence direct electrical stimulation methodology and sensitivity, limiting its use in children.

CONCLUSIONS

Therefore, even though awake procedure with cortical and axonal stimulation mapping can be adapted in a specific subgroup of children with a diffuse glioma from the age of 10 years, only few pediatric patients are nonetheless candidates for awake brain surgery.

Effects of dexmedetomidine postconditioning on myocardial ischemia and the role of the PI3K/Akt-dependent signaling pathway in reperfusion injury

The present study aimed to determine whether post-ischemic treatment with dexmedetomidine (DEX) protected the heart against acute myocardial ischemia/reperfusion (I/R)-induced injury in rats. The phosphatidylinositol-3 kinase/protein kinase B(PI3K/Akt)-dependent signaling pathway was also investigated. Male Sprague Dawley rats (n=64) were subjected to ligation of the left anterior descending artery (LAD), which produced ischemia for 25 min, followed by reperfusion. Following LAD ligation, rats were treated with DEX (5, 10 and 20 µg/kg) or underwent post-ischemic conditioning, which included three cycles of ischemic insult. In order to determine the role of the PI3K/Akt signaling pathway, wortmannin (Wort), a PI3K inhibitor, was used to treat a group of rats that had also been treated with DEX (20 µg/kg). Post-reperfusion, lactate dehydrogenase (LDH), cardiac troponin I (cTnI), creatine kinase isoenzymes (CK-MB), superoxide dismutase (SOD) and malondialdehyde (MDA) serum levels were measured using an ultraviolet spectrophotometer. The protein expression levels of phosphorylated (p)-Akt, Ser9-p-glycogen synthase kinase-3β (p-GSK-3β) and cleaved caspase-3 were detected in heart tissue by western blotting. The mRNA expression levels of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were detected using reverse transcription-polymerase chain reaction. At the end of the experiment, the hearts were removed and perfused in an isolated perfusion heart apparatus with Evans blue (1%) in order to determine the non-ischemic areas. The risk and infarct areas of the heart were not dyed. As expected, I/R induced myocardial infarction, as determined by the increased serum levels of cTnI, CK-MB and MDA, and the decreased levels of SOD. Post-ischemic treatment with DEX increased the expression levels of p-Akt and p-GSK-3β, whereas caspase-3 expression was reduced following DEX treatment compared with in the I/R group. Compared with the I/R group, the ratio of Bcl-2/Bax at the mRNA level was elevated in the DEX and ischemic post-conditioning groups, whereas the expression levels of Bax were decreased. Conversely, the effects of DEX were attenuated by Wort. These results indicated that, similar to post-ischemic conditioning, post-ischemic treatment with DEX protects the heart against I/R via the PI3K/Akt-dependent signaling pathway, possibly by activating GSK-3β.

Dexmedetomidine decreases the emergence agitation in infant patients undergoing cleft palate repair surgery after general anesthesia

Background

To determine whether continuous intravenous infusion of dexmedetomidine (DEX) can affect the incidence of Emergence Agitation (EA) after general anesthesia in infant undergoing cleft palate repair surgery.

Methods

Forty infants underwent cleft palate repair surgery under general anesthesia were randomly divided into the DEX (D) group and Placebo (P) groups. Patients in group D received continuous intravenous infusion of DEX 0.8 μg · kg-1 · min-1 after the induction. Patients in group P were administered with continuous intravenous infusion of the equivalent volume of normal saline. Both groups were induced with fentanyl 0.005 mg/Kg, propofol 2 mg/Kg and cisatracurium 0.2 mg/Kg. Anaesthesia was maintained with continuous intravenous infusion of propofol (2 mg/Kg · h), remifentanil (0.1 μg/Kg · h), and inhalation of 1 to 3 % sevoflurane.

Result

The heart rate (HR) in group P was significant higher than that in group D at the time of operation (P < 0.05), postoperative 15 min, 30 min and the time of extubation (P < 0.01). The mean arterial pressure (MAP) in group P was higher comparing with MAP in group D at the time of extubation (P < 0.05). The spontaneous eye opening times and spontaneous arm or leg motion times were longer in group D (P < 0.05). The mean agitation scores of patients in group D were significantly lower than that in group P (P < 0.01). However, the incidence of EA in group P and group D was 90 % and 15 % (P <0.05).

Conclusion

The continuous intravenous infusion of DEX after induction could significantly reduce the occurrence of EA.

Trial registration

The Chinese Clinical Trial Register ChiCTR-TRC-13003865

Neuroprotective effect of dexmedetomidine on hyperoxia-induced toxicity in the neonatal rat brain

Dexmedetomidine is a highly selective agonist of α2-receptors with sedative, anxiolytic, analgesic, and anesthetic properties. Neuroprotective effects of dexmedetomidine have been reported in various brain injury models. In the present study, we investigated the effects of dexmedetomidine on neurodegeneration, oxidative stress markers, and inflammation following the induction of hyperoxia in neonatal rats. Six-day-old Wistar rats received different concentrations of dexmedetomidine (1, 5, or 10 µg/kg bodyweight) and were exposed to 80% oxygen for 24 h. Sex-matched littermates kept in room air and injected with normal saline or dexmedetomidine served as controls. Dexmedetomidine pretreatment significantly reduced hyperoxia-induced neurodegeneration in different brain regions of the neonatal rat. In addition, dexmedetomidine restored the reduced/oxidized glutathione ratio and attenuated the levels of malondialdehyde, a marker of lipid peroxidation, after exposure to high oxygen concentration. Moreover, administration of dexmedetomidine induced downregulation of IL-1β on mRNA and protein level in the developing rat brain. Dexmedetomidine provides protections against toxic oxygen induced neonatal brain injury which is likely associated with oxidative stress signaling and inflammatory cytokines. Our results suggest that dexmedetomidine may have a therapeutic potential since oxygen administration to neonates is sometimes inevitable.

Awake craniotomy: A qualitative review and future challenges

Neurosurgery in awake patients incorporates newer technologies that require the anesthesiologists to update their skills and evolve their methodologies. They need effective communication skills and knowledge of selecting the right anesthetic drugs to ensure adequate analgesia, akinesia, along with patient satisfaction with the anesthetic conduct throughout the procedure. The challenge of providing adequate anesthetic care to an awake patient for intracranial surgery requires more than routine vigilance about anesthetic management.

Pediatric awake craniotomy and intra-operative stimulation mapping

The indications for operating on lesions in or near areas of cortical eloquence balance the benefit of resection with the risk of permanent neurological deficit. In adults, awake craniotomy has become a versatile tool in tumor, epilepsy and functional neurosurgery, permitting intra-operative stimulation mapping particularly for language, sensory and motor cortical pathways. This allows for maximal tumor resection with considerable reduction in the risk of post-operative speech and motor deficits. We report our experience of awake craniotomy and cortical stimulation for epilepsy and supratentorial tumors located in and around eloquent areas in a pediatric population (n=10, five females). The presenting symptom was mainly seizures and all children had normal neurological examinations. Neuroimaging showed lesions in the left opercular (n=4) and precentral or peri-sylvian regions (n=6). Three right-sided and seven left-sided awake craniotomies were performed. Two patients had a history of prior craniotomy. All patients had intra-operative mapping for either speech or motor or both using cortical stimulation. The surgical goal for tumor patients was gross total resection, while for all epilepsy procedures, focal cortical resections were completed without any difficulty. None of the patients had permanent post-operative neurologic deficits. The patient with an epileptic focus over the speech area in the left frontal lobe had a mild word finding difficulty post-operatively but this improved progressively. Follow-up ranged from 6 to 27 months. Pediatric awake craniotomy with intra-operative mapping is a precise, safe and reliable method allowing for resection of lesions in eloquent areas. Further validations on larger number of patients will be needed to verify the utility of this technique in the pediatric population.

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.

Challenges in pediatric neuroanesthesia: awake craniotomy, intraoperative magnetic resonance imaging, and interventional neuroradiology

This article gives a review of 3 challenges in caring for children undergoing neurosurgical and neurointerventional procedures. Anesthesiologists may have experience with certain aspects of these situations but may not have extensive experience with each clinical setting. This review addresses issues with awake craniotomy, intraoperative magnetic resonance imaging, and neurointerventional procedures in children with neurologic disease. Familiarization with these complex clinical scenarios and their unique considerations allows the anesthesiologist to deliver optimal care and helps facilitate the best possible outcome for these patients.

Comparison of dexmedetomidine and propofol for conscious sedation in awake craniotomy: a prospective, double-blind, randomized, and controlled clinical trial

BACKGROUND

It has been reported that dexmedetomidine (DEX) can be used for conscious sedation in awake craniotomy, but few data exist to compare DEX versus propofol (PRO).

OBJECTIVE

To compare the efficacy and safety of DEX versus PRO for conscious sedation in awake craniotomy.

METHODS

Thirty patients of American Society of Anesthesiologists grade I-II scheduled for awake craniotomy, were randomized into 2 groups each containing 15 subjects. Group D received DEX and group P received PRO. Two minutes after tracheal intubation (T1), PRO (target plasma concentration) was titrated down to 1 to 4 µg/mL in group P. In group D, PRO was discontinued and DEX was administered 1.0 µg/kg followed by a maintenance dose of 0.2 to 0.7 µg/kg/h. The surgeon preset the anticipated awake point-in-time (T0) preoperatively. Ten minutes before T0 (T3), DEX was titrated down to 0.2 µg/kg/h in group D, PRO was discontinued and normal saline (placebo) 5 mL/h was infused in group P. Arousal time, quality of revival and adverse events during the awake period, degree of satisfaction from surgeons and patients were recorded.

RESULTS

Arousal time was significantly shorter in group D than in group P (P < .001). The quality of revival during the awake period in group D was similar to that of group P (P = .68). The degree of satisfaction of surgeons was significantly higher in group D than in group P (P < .001), but no difference was found between the 2 groups with respect to patient satisfaction (P = .80). There was no difference between the 2 groups in the incidence of adverse events during the awake period (P > .05).

CONCLUSIONS

Either DEX or PRO can be effectively and safely used for conscious sedation in awake craniotomy. Comparing the two, DEX produced a shorter arousal time and a higher degree of surgeon satisfaction.

[Awake craniotomy. Considerations in special situations]

Awake craniotomy was the earliest surgical procedure known, and it has become fashionable again. In the past it was used for the surgical management of intractable epilepsy, but nowadays, its indications are increasing, and it is a widely recognized technique for the resection of mass lesions involving the eloquent cortex, and for deep brain stimulation. The procedure is safe, provides excellent results, and saves money and resources. The anesthesiologist should know the principles underlying neuroanesthesia, the technique of scalp blockade, and the sedation protocols, as well as feeling comfortable with advanced airway management. The main anesthetic aim is to keep patients cooperating when required (analgesia-based anesthesia). This review attempts to summarize the most recent evidence from the clinical literature, a long as the number of patients undergoing craniotomies in the awake state are increasing, specifically in the pediatric population.

Intermittent general anesthesia with controlled ventilation for asleep-awake-asleep brain surgery: a prospective series of 140 gliomas in eloquent areas

BACKGROUND

Awake brain tumor surgery is a unique opportunity for mapping sensorimotor and cognitive functions, allowing the operator to optimize the resection while preserving the patient's quality of life. During this type of procedure, active participation of the patient is necessary.

OBJECTIVE

To assess the efficacy and safety of a method of intermittent general anesthesia with controlled ventilation for performing invasive cerebral mapping.

METHODS

We report our prospective and observational single-center study with an asleep-awake-asleep protocol. Aspects of feasibility, airway management, timing of each phase, and occurrence of adverse events were detailed.

RESULTS

During a 35-month period, 140 patients underwent resection of a glioma in an eloquent area. During the asleep phases, controlled ventilation with a laryngeal mask was always efficient. Orotracheal intubation was performed for some patients for the second asleep period. The patients remained fully awake for a mean time of 98 minutes. Postural discomfort was reported in 17.8% of cases. There was 1 case of aspiration of gastric contents with a favorable outcome and no mortality.

CONCLUSION

Intermittent general anesthesia with controlled ventilation for this type of neurosurgical procedure remains an anesthesiological challenge. However, the results of this study suggest that it may be feasible, reproducible, and relatively safe in the context of a standardized protocol involving members of both anesthesiology and surgery teams. Such a technique has a great potential to improve the surgical results, from both oncological and functional perspectives.

Dexmedetomidine: current role in anesthesia and intensive care

BACKGROUND AND OBJECTIVES

To update and review the application of dexmedetomidine in anesthesia and intensive care. This study is a comprehensive review of clinical uses, pharmacology, pharmacokinetics, mechanism of action and adverse effects of dexmedetomidine.

CONTENT

The effective use of sedative-hypnotic agents and analgesics is an integral part of comfort and safety of patients. Dexmedetomidine is a potent and highly selective α-2 adrenoceptor agonist with sympatholytic, sedative, amnestic, and analgesic properties, which has been described as a useful and safe adjunct in many clinical applications. It provides a unique "conscious sedation", analgesia, without respiratory depression. The current reviewed uses include sedation at Intensive Care Unit-ICU (both adult and pediatric), emergency department, regional and general anesthesia, neurosurgery, sedation for pediatric procedures, awake fiber-optic intubation, cardiac surgery and bariatric surgery.

CONCLUSIONS

Dexmedetomidine offers a unique ability of providing both sedation and analgesia without respiratory depression. It is a new agent with a wide safety margin, excellent sedative capacity and moderate analgesic properties. Although its wide use is currently in patients of surgical and non-surgical intensive care units, dexmedetomidine seems to have promising future applications in neuroprotection, cardioprotection and renoprotection. More detailed studies are required to define its role as sedative in critical, neurosurgical and pediatric patients, as anesthesia adjunct and sedative during procedures.

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.

Effects of dexmedetomidine added to caudal ropivacaine in paediatric lower abdominal surgeries

Purpose:

The objectives of this study were to compare the effects of caudal dexmedetomidine combined with ropivacaine to provide postoperative analgesia in children and also to establish its safety in the paediatric population.

Methods:

In a randomised, prospective, parallel group, double-blinded study, 60 children were recruited and allocated into two groups: Group RD (n=30) received 0.25% ropivacaine 1 ml/kg with dexmedetomidine 2 μg/kg, making the volume to 0.5 ml and Group R (n=30) received 0.25% ropivacaine 1 ml/kg + 0.5 ml normal saline. Induction of anaesthesia was achieved with 50% N₂O and 8% sevoflurane in oxygen in spontaneous ventilation. An appropriate-sized LMA was then inserted and a caudal block performed in all patients. Behaviour during emergence was rated with a 4-point scale, sedation with Ramsay's sedation scale, and pain assessed with face, legs, activity, cry, consolability (FLACC) pain score.

Results:

The duration of postoperative analgesia recorded a median of 5.5 hours in Group R compared with 14.5 hours in Group RD, with a P value of <0.001. Group R patients achieved a statistically significant higher FLACC score compared with Group RD patients. The difference between the means of mean sedation score, emergence behaviour score, mean emergence time was statistically highly significant (P<0.001). The peri-operative haemodynamics were stable among both the groups.

Conclusion:

Caudal dexmedetomidine (2 μg/kg) with 0.25% ropivacaine (1 ml/kg) for paediatric lower abdominal surgeries achieved significant postoperative pain relief that resulted in a better quality of sleep and a prolonged duration of arousable sedation and produced less incidence of emergence agitation following sevoflurane anaesthesia.

Dexmedetomidine: pediatric pharmacology, clinical uses and safety

IMPORTANCE OF THE FIELD

Dexmedetomidine is an α(2)-adrenoceptor agonist with sedative, anxiolytic and analgesic properties. It is used off-label in pediatric patients due to its efficacy and lack of adverse respiratory effects. Dexmedetomidine may cause severe circulatory complications in adults. Despite its popularity, the safety of dexmedetomidine in the pediatric population has not been extensively studied.

AREAS COVERED IN THIS REVIEW

This article reviews the current literature (up to 2010) focusing on applications and safety of dexmedetomidine administered to pediatric patients.

WHAT THE READER WILL GAIN

Dexmedetomidine is a useful sedative and anxiolytic drug in the pediatric intensive care unit as well as during diagnostic and therapeutic procedures. Deleterious effects of dexmedetomidine include hypotension and bradycardia. Additionally, hypertension may occur during the "loading dose" or with high infusion rates. Few studies have been performed to evaluate the safety of dexmedetomidine in pediatrics. The development of tolerance and withdrawal has not been studied in children.

TAKE HOME MESSAGE

Despite its favorable respiratory profile, dexmedetomidine may cause deleterious cardiovascular effects. Close monitoring of circulatory dynamics and judicious titration is recommended. Further studies are needed to better define adverse effects following long-term infusions as well as in special populations such as pre-term infants.

Anesthesia for pediatric deep brain stimulation

In patients refractory to medical therapy, deep brain stimulations (DBSs) have emerged as the treatment of movement disorders particularly Parkinson's disease. Their use has also been extended in pediatric and adult patients to treat epileptogenic foci. We here performed a retrospective chart review of anesthesia records from 28 pediatric cases of patients who underwent DBS implantation for dystonia using combinations of dexmedetomidine and propofol-based anesthesia. Complications with anesthetic techniques including airway and cardiovascular difficulties were analyzed.

Update on dexmedetomidine: use in nonintubated patients requiring sedation for surgical procedures

Dexmedetomidine was introduced two decades ago as a sedative and supplement to sedation in the intensive care unit for patients whose trachea was intubated. However, since that time dexmedetomidine has been commonly used as a sedative and hypnotic for patients undergoing procedures without the need for tracheal intubation. This review focuses on the application of dexmedetomidine as a sedative and/or total anesthetic in patients undergoing procedures without the need for tracheal intubation. Dexmedetomidine was used for sedation in monitored anesthesia care (MAC), airway procedures including fiberoptic bronchoscopy, dental procedures, ophthalmological procedures, head and neck procedures, neurosurgery, and vascular surgery. Additionally, dexmedetomidine was used for the sedation of pediatric patients undergoing different type of procedures such as cardiac catheterization and magnetic resonance imaging. Dexmedetomidine loading dose ranged from 0.5 to 5 μg kg⁻¹, and infusion dose ranged from 0.2 to 10 μg kg⁻¹ h⁻¹. Dexmedetomidine was administered in conjunction with local anesthesia and/or other sedatives. Ketamine was administered with dexmedetomidine and opposed its bradycardiac effects. Dexmedetomidine may by useful in patients needing sedation without tracheal intubation. The literature suggests potential use of dexmedetomidine solely or as an adjunctive agent to other sedation agents. Dexmedetomidine was especially useful when spontaneous breathing was essential such as in procedures on the airway, or when sudden awakening from sedation was required such as for cooperative clinical examination during craniotomies.

Dexmedetomidine: perioperative applications in children

Dexmedetomidine is a highly specific and selective alpha-2-adrenergic agonist with sedative, anxiolytic, and organ protective effects. Its clinical applications in children include premedication, prevention of emergence delirium, as part of multimodal anesthetic regimen and sedation in the pediatric intensive care unit. Its role in neuroprotection in children undergoing anesthesia should be explored. In this review, various uses of dexmedetomidine are discussed in detail.

Dexmedetomidine/ketamine for diagnostic cardiac catheterization in a child with idiopathic pulmonary hypertension

The use of a combination of dexmedetomidine and ketamine to provide procedural sedation in a 12-year old boy with a diagnosis of idopathic pulmonary hypertension and a behavioral disorder, undergoing diagnostic cardiac catheterization, is presented. Following a loading dose of ketamine one mg/kg and dexmedetomidine one mcg/kg, an infusion of dexmedetomidine at one mcg/kg/hr was used with the patient breathing spontaneously. Stable hemodynamics were observed throughout the procedure and pulmonary vascular resistance was measured under three conditions. The dexmedetomidine infusion was continued for two hours post-catheterization, facilitating a smooth emergence.

Dexmedetomidine Use in Pediatric Intensive Care and Procedural Sedation

OBJECTIVE

Dexmedetomidine was approved by the Food and Drug Administration in 1999 for the sedation of adults receiving mechanical ventilation in an intensive care setting. It provides sedation with minimal effects on respiratory function and may be used prior to, during, and following extubation. Based on its efficacy in adults, dexmedetomidine is now being explored as an alternative or adjunct to benzodiazepines and opioids in the pediatric intensive care setting. This review describes the studies evaluating the safety and efficacy dexmedetomidine in infants and children and provides recommendations on dosing and monitoring.

METHODS

The MEDLINE (1950–November 2009) database was searched for pertinent abstracts, using the key term dexmedetomidine. Additional references were obtained from the bibliographies of the articles reviewed and the manufacturer. All available English-language case reports, clinical trials, retrospective studies, and review articles were evaluated.

RESULTS

Over two dozen case series and clinical studies have documented the utility of dexmedetomidine as a sedative in children requiring mechanical ventilation or procedural sedation. In several papers, dexmedetomidine use resulted in a reduction in the dose or discontinuation of other sedative agents. It may be of particular benefit in children with neurologic impairment or in those who do not tolerate benzodiazepines. The most frequent adverse effects reported with dexmedetomidine have been hypotension and bradycardia, in 10% to 20% of patients. These effects typically resolve with dose reduction.

CONCLUSIONS

Dexmedetomidine offers an additional choice for the sedation of children receiving mechanical ventilation in the intensive care setting or requiring procedural sedation. While dexmedetomidine is well tolerated when used at recommended doses, it has the potential to cause hypotension and bradycardia and requires close monitoring. In addition to clinical trials currently underway, larger controlled studies are needed to further define the role of dexmedetomidine in pediatric intensive care.

Awake craniotomy

Awake craniotomy has become an increasingly frequent procedure. In this paper, the principles of its anaesthetic management are reviewed. The means allowing achievement of anaesthetic objectives are described, with emphasis on points that determine success of the procedure. A careful and adequate selection and preparation of patients are mandatory, and the intervening team must be a skilled team. Choosing an awake technique or general anaesthesia depends on several factors, including the risk of obstructive apnoea, seizures, nausea and vomiting, patient's ability to cooperate, and localization of lesions. The main challenge of intraoperative anaesthetic management relies on the ability of rapidly adjusting the level of sedation and analgesia according to the sequence of surgical events, while ensuring haemodynamic stability, adequate ventilation, and minimal interference with eventual electrophysiological recordings. Throughout the procedure, complications must be anticipated and managed according to predefined guidelines. More prospective randomized clinical trials are still needed to improve safety and efficacy of awake craniotomies, as well as to validate this technique in comparison with more conventional anaesthetic management.