Perioperative management of complex skull base surgery: the anesthesiologist's point of view

Special Considerations in Pediatric Endoscopic Skull Base Surgery

Originally pioneered in adults, endoscopic endonasal approaches for skull base pathology are being increasingly applied as a minimally invasive alternative for young children. Intrinsic anatomic differences between these patient populations have sparked discussions on the feasibility, safety, and efficacy of these techniques in pediatric patients. This work aims to serve as a primer for clinicians engaged in the rapidly evolving field of pediatric endoscopic skull base surgery. A succinct overview of relevant embryology, sinonasal anatomy, and diagnostic workup is presented to emphasize key differences and unique technical considerations. Additional discussions regarding select skull base lesions, reconstructive paradigms, potential surgical complications, and postoperative care are also highlighted in the setting of multidisciplinary teams.

360 Degrees Endoscopic Access to and Through the Orbit

The treatment of pathologies located within and surrounding the orbit poses considerable surgical challenges, due to the intricate presence of critical neurovascular structures in such deep, confined spaces. Historically, transcranial and craniofacial approaches have been widely employed to deal with orbital pathologies. However, recent decades have witnessed the emergence of minimally invasive techniques aimed at reducing morbidity. Among these techniques are the endoscopic endonasal approach and the subsequently developed endoscopic transorbital approach (ETOA), encompassing both endonasal and transpalpebral approaches. These innovative methods not only facilitate the management of intraorbital lesions but also offer access to deep-seated lesions within the anterior, middle, and posterior cranial fossa via specific transorbital and endonasal corridors. Contemporary research indicates that ETOAs have demonstrated exceptional outcomes in terms of morbidity rates, cosmetic results, and complication rates. This study aims to provide a comprehensive description of endoscopic-assisted techniques that enable a 360° access to the orbit and its surrounding regions. The investigation will delve into indications, advantages, and limitations associated with different approaches, while also drawing comparisons between endoscopic approaches and traditional microsurgical transcranial approaches.

Postoperative protocols following endoscopic skull base surgery: An evidence-based review with recommendations

BACKGROUND

Postoperative management strategies for endoscopic skull base surgery (ESBS) vary widely because of limited evidence-based guidance.

METHODS

The PubMed, EMBASE, and Cochrane databases were systematically reviewed from January 1990 through February 2022 to examine 18 postoperative considerations for ESBS. Nonhuman studies, articles written in a language other than English, and case reports were excluded. Studies were assessed for levels of evidence, and each topic's aggregate grade of evidence was evaluated.

RESULTS

A total of 74 studies reporting on 18 postoperative practices were reviewed. Postoperative pain management, prophylactic antibiotics, and lumbar drain use had the highest grades of evidence (B). The literature currently lacks high quality evidence for a majority of the reviewed ESBS precautions. There were no relevant studies to address postoperative urinary catheter use and medical intracranial pressure reduction.

CONCLUSION

The evidence for postoperative ESBS precautions is heterogeneous, scarce, and generally of low quality. Although this review identified the best evidence available in the literature, it suggests the urgent need for more robust evidence. Therefore, additional high-quality studies are needed in order to devise optimal postoperative ESBS protocols.

Opioid Prescriptions Following Otologic Surgery: A Population-Based Study

OBJECTIVE

To examine postoperative opioid-prescribing patterns following otologic surgery.

STUDY DESIGN

Retrospective population-based descriptive study.

SETTING

All hospitals in the Canadian province of Ontario.

METHODS

Of all patients with advanced ear surgery between July 1, 2012, and March 31, 2019, 7 cohorts were constructed: tympanoplasty with or without ossiculoplasty (n = 7812), atticotomy/limited mastoidectomy (n = 1371), mastoidectomy (n = 3717), semicircular canal occlusion (SCO; n = 179), stapedectomy (n = 2735), bone-implanted hearing aid insertion (n = 280), and cochlear implant (n = 2169). Prescriptions filled for narcotics postoperatively were calculated per morphine milligram equivalent (MME) opioid dose. Multivariable regression was used to determine predictors of higher opioid doses.

RESULTS

The mean ± SD MMEs prescribed were as follows: tympanoplasty with or without ossiculoplasty, 246.77 ± 1380.78; atticotomy/limited mastoidectomy, 283.32 ± 956.10; mastoidectomy, 280.56 ± 1018.50; SCO, 328.61 ± 1090.86; stapedectomy, 164.64 ± 657.18; bone-implanted hearing aid insertion, 326.11 ± 1054.66; and cochlear implant, 200.87 ± 639.93. SCO (odds ratio [OR], 1.69 [95% CI, 1.16-2.48]) and mastoidectomy (OR, 1.50 [95% CI, 1.36-1.66]) were associated with higher opioid doses than tympanoplasty-ossiculoplasty. Asthma (OR, 1.24 [95% CI, 1.12-1.38]), chronic obstructive pulmonary disease (OR, 1.29 [95% CI, 1.12-1.47]), myocardial infarction (OR, 1.33 [95% CI, 1.05-1.68]), diabetes (OR, 1.22 [95% CI, 1.08-1.39]), and substance-related and addictive disorders (OR, 2.59 [95% CI, 1.67-4.00]) were associated with higher opioid doses prescribed. Overall MME prescribed by year demonstrates a sharp drop from 2017-2018 to 2018-2019.

CONCLUSION

This large comprehensive population study provides insight into the prescribing patterns following otologic surgery. The large amounts prescribed and substantial variation require further study to determine barriers that limit good opioid-prescribing stewardship in the postoperative period.

Tranexamic acid to reduce operative blood loss in brain tumor surgery: A meta-analysis

Background:

Major blood loss during neurosurgery may result in a variety of complications, such as potentially fatal hemodynamic instability. Brain tumor and skull base surgery is among the high bleeding risk procedures. Tranexamic acid (TXA) has been found to reduce bleeding events in various fields of medicine.

Methods:

We searched for all randomized controlled trials published in English or Bahasa which compared the use of TXA with placebo in brain tumor surgery. The studies should include adult patients with intracranial tumor who received TXA before skin incision. The primary and secondary outcomes are intraoperative blood loss and the need of transfusion.

Results:

This meta-analysis included a total of 200 patients from three studies. TXA resulted in less blood loss with pooled mean difference of −292.80 (95% CI, −431.63, −153.96, P<0.05). The need of transfusion was not significant between TXA and control group (pooled mean difference −85.36, 95% CI, −213.23 – (42.51), P=0.19).

Conclusion:

TXA reduced the volume of blood loss but did not reduce the need of blood transfusion.

Options to manage postcraniotomy acute pain in neurosurgery: no protocol available

The physical processes of incision, traction and hemostasis used for craniotomy, stimulate nerve fibers and specific nociceptors, resulting in postoperative pain. During the first 24 h after craniotomy, 87% of patients have postoperatory pain. The rate of suffering pain after craniotomy falls 3% for every year of life. The objective of this study is to review the available therapeutic options to help physicians treating this pain, and discuss pain mechanisms, pathophysiology, plasticity, risk factors and psychological factors. This is a narrative review of the literature from 1970 to June 2019. Data were collected by doing a search in PubMed, EMBASE, Cochrane Reviews and a manual search of all relevant literature references. The literature includes some drugs treatment: Opioids, codeine, morphine, and tramadol, anti-inflammatory non-steroids such as cyclooxygenase-2 inhibitors, gabapentin. It discusses: side effects, pharmacodynamics and indications of each drug, anatomy and Inervation of Skull and its Linigs, pathogenesis of pain Post-craniotomy, scalp nerve block, surgical nerve injury, neuronal plasticity, surgical factors and chronic post-surgical pain.

Perioperative Pain Management Following Otologic Surgery

Otologic surgery involves a broad range of procedures. In general, postoperative pain from most otologic surgeries can be managed with little to no opioids, and surgeons should make a concerted effort to minimize narcotic prescriptions in the midst of the opioid crisis. Many procedures, including transcanal surgeries and even postauricular surgeries, may performed with local anesthetic in selected patients. Multimodal pain regimens, local anesthesia, and alternative approaches have shown promise in minimizing narcotic use, and should be considered. Preoperative counseling to appropriately manage expectations and goals is imperative for patient satisfaction and safety.

Designing a pain management protocol for craniotomy: A narrative review and consideration of promising practices

BACKGROUND

Craniotomy is a relatively common surgical procedure with a high incidence of postoperative pain. Development of standardized pain management and enhanced recovery after surgery (ERAS) protocols are necessary and crucial to optimize outcomes and patient satisfaction and reduce health care costs.

METHODS

This work is based upon a literature search of published manuscripts (between 1996 and 2017) from Pubmed, Cochrane Central Register, and Google Scholar. It seeks to both synthesize and review our current scientific understanding of postcraniotomy pain and its part in neurosurgical ERAS protocols.

RESULTS

Strategies to ameliorate craniotomy pain demand interventions during all phases of patient care: preoperative, intraoperative, and postoperative interventions. Pain management should begin in the perioperative period with risk assessment, patient education, and premedication. In the intraoperative period, modifications in anesthesia technique, choice of opioids, acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs), regional techniques, dexmedetomidine, ketamine, lidocaine, corticosteroids, and interdisciplinary communication are all strategies to consider and possibly deploy. Opioids remain the mainstay for pain relief, but patient-controlled analgesia, NSAIDs, standardization of pain management, bio/behavioral interventions, modification of head dressings as well as patient-centric management are useful opportunities that potentially improve patient care.

CONCLUSIONS

Future research on mechanisms, predictors, treatments, and pain management pathways will help define the combinations of interventions that optimize pain outcomes.

Use of Tranexamic Acid Is Associated with Reduced Blood Product Transfusion in Complex Skull Base Neurosurgical Procedures: A Retrospective Cohort Study

BACKGROUND

Compared with other procedures, complex skull base neurosurgery has the potential for increased intraoperative blood loss yet coagulation near eloquent cranial structures should be minimized. The safety and efficacy of the antifibrinolytic, tranexamic acid in elective neurosurgical procedures is not known. Our primary objective was to determine the relationship between the use of tranexamic acid and transfusion at our institution. Our secondary objective was to determine the incidence of adverse events associated with the use of tranexamic acid.

METHODS

In this retrospective cohort study, we included all patients who underwent complex skull base neurosurgical procedures at our institution between 2001 and 2013. Tranexamic acid was introduced during these procedures in 2006. Patient and surgical variables, transfusion data, and adverse events in the perioperative period were abstracted from the medical record. The rates of transfusion and adverse events were compared between patients who did and did not receive tranexamic acid. Multivariate regression was used to identify independent predictors of perioperative transfusion.

RESULTS

We compared 245 patients who received tranexamic acid with 274 patients who did not receive the drug during the study period. The 2 groups were similar, with the exception that patients who received tranexamic acid had larger tumors (mean, 3.5 vs 2.9 cm; P < 0.001) and longer procedures (mean, 7.2 vs 6.2 hours, P < 0.001). The rate of perioperative transfusion in patients who received tranexamic acid was lower (7% vs 13%, P = 0.04). After adjusting for preoperative hemoglobin, tumor diameter, and surgical procedure category, the use of tranexamic acid was independently predictive of perioperative transfusion (adjusted odds ratio, 0.32; 95% confidence interval, 0.15-0.65, P = 0.002). The rates of thromboembolic events and seizure were similar between the 2 groups.

CONCLUSIONS

Our results demonstrate that tranexamic acid use is associated with reduced transfusion rates in our study population, with no apparent increase in seizure or thrombotic complications. Our data support the need for further randomized clinical trials to evaluate the efficacy and safety of tranexamic acid on perioperative blood loss during complex skull base neurosurgery.

Neuroanesthesia

Neuroanesthesia is a subspecialty area of anesthesia that deals with the complex relationships of anesthetic medications, neurosurgical procedures, and the critical care issues that surround the management of these patients. In this chapter we will focus on a brief overview of the key features associated with the management of patients undergoing neurosurgical procedures, including a review of hemodynamic/neurologic effects of anesthetic agents, neurophysiologic monitoring, and unique medical complications associated with these procedures. For successful patient outcomes, multidisciplinary approaches and effective team communications are essential in these high-intensity environments. This chapter should serve as an introduction to the multitude of issues that face the anesthesiologist and surgeon when dealing with this patient population.

Somatosensory evoked potentials help prevent positioning-related brachial plexus injury during skull base surgery

OBJECTIVE

Evaluate the use of somatosensory evoked potentials (SSEP) monitoring to detect positioning-related brachial plexus injury during skull base surgery.

STUDY DESIGN

Prospective cohort observational study.

SETTING

University Hospital.

SUBJECTS AND METHODS

Patients undergoing skull base surgery had a focused neurologic exam of the brachial plexus performed before and after surgery. Under stable anesthesia, brachial plexus SSEP values were obtained before and after surgical positioning. Significant SSEP changes required a readjustment of arm or neck positions. SSEPs were assessed every 30 minutes. If changes were noted, position was readjusted and SSEPs were reassessed until surgical completion. Demographic data, neurologic exams, SSEP latency, and amplitude values were recorded. Persistent changes were correlated with postoperative neurologic findings.

RESULTS

Sixty-five patients, 15 to 77 years old, were studied. Six patients (9.2%) developed SSEP amplitude changes after positioning (average amplitude decrease 72.8%). One patient had a significant latency increase. The sensitivity of SSEP for detection of injury was 57%, while specificity was 94.7%. The average body mass index (BMI) of patients with normal and abnormal SSEPs was 28.7 ± 5.6 versus 29.2 ± 8.0, respectively. Average BMI of patients with postoperative symptoms regardless of SSEP findings was 33.8 ± 4.3. Two patients who had persistent SSEP changes after positioning had BMIs of 40.1 and 31.2 kg/m(2), respectively. Improvement in neurologic findings occurred in all patients after surgery.

CONCLUSIONS

This study demonstrates that upper extremity nerve stress can be detected in real time using SSEP and may be of value in protecting patients from nerve injury undergoing lateral skull base surgery.

Body Mass Index Predicts Risk for Complications from Transtemporal Cerebellopontine Angle Surgery

Objectives

To determine the relationship between body mass index (BMI) and risk for specific complications from transtemporal cerebellopontine angle (CPA) surgery for nonmalignant disease.

Study Design

Case series with chart review.

Setting

Tertiary-care academic hospital.

Subjects and Methods

Retrospective review of 134 consecutive patients undergoing transtemporal cerebellopontine angle surgery for nonmalignant disease from 2009 to 2011. Data were collected regarding demographics, body mass index, intraoperative details, hospital stay, and complications including cerebrospinal fluid leak, wound complications, and brachial plexopathy.

Results

One hundred thirty-four patients were analyzed with a mean preoperative body mass index of 28.58. Statistical analysis demonstrated a significant difference in body mass index between patients with a postoperative cerebrospinal fluid leak and those without ( P = .04), as well as a similar significant difference between those experiencing postoperative brachial plexopathy and those with no such complication ( P = .03). Logistical regression analysis confirmed that body mass index is significant in predicting both postoperative cerebrospinal fluid leak ( P = .004; odds ratio, 1.10) and brachial plexopathy ( P = .04; odds ratio, 1.07). Elevated body mass index was not significant in predicting wound complications or increased hospital stay beyond postoperative day 3.

Conclusion

Risk of cerebrospinal fluid leak and brachial plexopathy is increased in patients with elevated body mass index undergoing surgery of the cerebellopontine angle. Consideration should be given to preoperative optimization via dietary and lifestyle modifications as well as intraoperative somatosensory evoked potential monitoring of the brachial plexus to decrease these risks.

The impact of hypotension due to the trigeminocardiac reflex on auditory function in vestibular schwannoma surgery

Object

Surgical manipulation of the fifth cranial nerve during its intra- or extracranial course may lead to bradycardia or even asystole as well as arterial hypotension, a phenomenon described as the trigeminocardiac reflex (TCR). The authors studied the impact of this reflex on postoperative auditory function in patients undergoing vestibular schwannoma (VS) surgery.

Methods

One hundred patients scheduled for VS surgery were studied prospectively for parameters influencing the postoperative auditory function. The evaluation included sex, age, pre- and postoperative auditory function, preoperative mean arterial blood pressure, preoperative medical diseases or medication (for example, antiarrhythmia drugs), tumor size and localization, and the intraoperative occurrence of the TCR.

The TCR, which occurred in 11% of the patients, influenced the postoperative hearing function in the patients with Hannover Class T3 and T4 VSs.

With an overall hearing preservation of 47%, 11.1% of the patients in the TCR group and 51.4% of those in the non-TCR group experienced preserved hearing function postoperatively. In cases involving larger tumors (Hannover Class T3 and T4), an intraoperative TCR was associated with a significantly worse postoperative hearing function during VS surgery (p = 0.005).

Conclusions

The hypotension following TCR is a negative prognostic factor for hearing preservation in patients undergoing VS surgery. Patients’ knowledge of this can be increased pre- and postoperatively. Further study of this phenomenon will advance the understanding of the underlying mechanisms and may help to improve hearing preservation by controlling the occurrence of the TCR.