Novelties for increased safety in cranio-vertebral surgery: a review.

The cranio-vertebral junction (CVJ) was formerly considered a surgical "no man's land" due to its complex anatomical and biomechanical features. Surgical approaches and hardware instrumentation have had to be tailored in order to achieve successful outcomes. Nowadays, thanks to the ongoing development of new technologies and surgical techniques, CVJ surgery has come to be widely performed in many spine centers. Accordingly, there is a drive to explore novel solutions and technological nuances that make CVJ surgery safer, faster, and more precise. Improved outcome in CVJ surgery has been achieved thanks to increased safety allowing for reduction in complication rates. The Authors present the latest technological advancements in CVJ surgery in terms of imaging, biomaterials, navigation, robotics, customized implants, 3D-printed technology, video-assisted approaches and neuromonitoring.

Role of Enhanced Recovery after Surgery (ERAS) Protocol in the Management of Elderly Patients with Glioblastoma.

OBJECTIVE: Among the already difficult management of neuro-oncological patients, the elderly population remains vulnerable. Because of the pathology and the comorbidities, they present a significantly higher rate of medical issues related to surgical management. Despite this, the surgical option, if feasible, remains the gold standard in these patients, and an Enhanced Recovery After Surgery (ERAS) protocol could improve the postoperative safety of the patients. With this purpose, we prepared this study with the aim of defining the postoperative hospital length of stay (LOS), but also of evaluating the postoperative morbidity, perioperative complications, and postoperative pain scores. METHODS: This was a retrospective, single-cohort study performed at an academic hospital (Department of Neurosurgery, Neurocenter of South Switzerland, Switzerland) on elderly patients who underwent craniotomy for glioblastoma. Patients were enrolled in a novel ERAS protocol from January 2022 to December 2022. Since this is a feasibility study and a direct comparison was not possible, we used a historical cohort of elderly patients who had undergone elective craniotomy surgery for glioblastoma as a control group. RESULTS: A total of 19 patients treated in our center for glioblastoma multiforme (GBM) who were aged over 75 years were included in this study. Among those, seven were newly recruited patients included in the ERAS protocol, while the remaining twelve were part of a historical cohort of previously treated patients. From a statistical point of view, the two cohorts were comparable in terms of baseline demographics. In the follow-up, it was shown that in the ERAS group, there was a reduction in the use of opioids after the surgical procedures that could be seen at 30 days (36.2% vs. 71.7%, p < 0.001), but also at 3 months, after surgery (33.0% vs. 80.0%, p < 0.001). A significant difference has also been documented in terms of mobilization and ambulation: compared to the historical cohort, in the ERAS group, there was a higher rate of mobilization (60.0% vs. 10.0%, p < 0.001), but also of ambulation (36.1% vs. 10.0%, p < 0.001). CONCLUSIONS: The ERAS protocol for the management of glioblastoma in elderly patients seems to be an effective option for reducing LOS in the hospital, as well as for reducing the number of days spent in the ICU, improving the general recovery of the patient, and reducing the costs associated with hospitalization.

Sacral Tarlov cysts: Neurophysiology abnormalities and correlation with pelvic sensory and visceral symptoms.

BACKGROUND AND PURPOSE: Recent studies suggest a possible association between Tarlov cysts (TCs), usually considered as incidental radiological findings, and neurological symptoms such as pain, numbness and urogenital complaints. The aim was to explore the relationship between TCs and sacral nerve root functions using pelvic neurophysiology tests, and to correlate changes with clinical symptoms and magnetic resonance imaging (MRI) findings. METHODS: Consecutive patients with sacral TCs, referred for pelvic neurophysiology testing and presenting with at least one symptom related to the pelvic area, participated in a cross-sectional review of symptoms using validated questionnaires. Findings of pelvic neurophysiology (pudendal sensory evoked potentials, sacral dermatomal sensory evoked potentials, external anal sphincter electromyography) and urodynamics testing were collected retrospectively. The relationship between neurophysiology, MRI findings and patients' symptoms was assessed using Fisher and ANOVA tests. RESULTS: Sixty-five females were included (mean age 51.2 ± 12.1 years). The commonest symptom was pain (92%). Urinary (91%), bowel (71%) and sexual (80%) symptoms were also frequently reported. Thirty-seven patients (57%) had abnormal neurophysiology findings reflecting sacral root dysfunction. No association was seen between MRI findings (size, location of the cysts, severity of compression) and neurophysiology. A negative association was observed between neurophysiology abnormalities and occurrence of urgency urinary incontinence (p = 0.03), detrusor overactivity (p < 0.01) and stress urinary incontinence (p = 0.04); however, there was no association with voiding difficulties. CONCLUSIONS: Contrary to current understanding, TCs are associated with injury to the sacral somatic innervation in the majority of patients with presumed symptomatic cysts. However, urinary incontinence is unlikely to be related to TC-induced nerve damage.

The cruciform drain: a technical note on the surgical management of cystic lesions of the sella.

BACKGROUND: The postoperative recurrence of cystic lesions of the sella is frequent and may require further surgery for re-drainage. OBJECTIVE: To tackle this problem, we propose to insert a small cross-shaped drain coursing from the cyst lumen to the suprasellar cistern. At this early stage of innovation, the technique is primarily intended for patients who present with a recurrence. METHODS: The cruciform drain is fashioned from the tip of a ventricular catheter and is inserted under endoscopic vision. We retrospectively reviewed the pre- and postoperative records of patients in whom this technique was implemented. RESULTS: A cruciform drain was placed in five patients since the introduction of the technique into our practice in 2018. The use of the cruciform drain did not impact upon the expected surgical workflow nor was it associated with adverse intraoperative events, but three patients did develop a postoperative CSF leak that was successfully treated in all cases. None of the patients showed re-collection of their cysts on early radiological follow-up. CONCLUSION: The cruciform drain is intended to prevent the renewed build-up of cystic fluid by allowing it to flow through and around the drain into the subarachnoid space. We have modified our repair protocol in response to the observed high CSF leak rate, as a basis for further development of the technique. Studies involving long-term follow-up will also be required to assess its efficacy in reducing cyst recurrence.

A patient-reported outcome measure for patients with pituitary adenoma undergoing transsphenoidal surgery.

PURPOSE: Pituitary adenomas affect patients' quality-of-life (QoL) across several domains, with long-term implications even following gross-total resection or disease remission. While clinical outcomes can assess treatment efficacy, they do not capture variations in QoL. We present the development and validation of a patient reported outcome measure (PROM) for patients with pituitary adenomas undergoing transsphenoidal surgery. METHODS: The COSMIN checklist informed the development of the pituitary outcome score (POS). Consecutive patients undergoing surgical treatment for suspected pituitary adenoma at a single centre were included prospectively. An expert focus group and patient interviews informed item generation. Item reduction was conducted through exploratory factor analysis and expert consensus, followed by assessment of the tool's validity, reliability, responsiveness, and interpretability. RESULTS: 96 patients with a median age of 50 years validated the POS. The final questionnaire included 25 questions with four subscales: EQ-5D-5L-QoL, Visual Symptoms, Endocrine Symptoms and Nasal Symptoms. CONCLUSION: The POS is the first validated PROM for patients undergoing transsphenoidal surgery for a pituitary adenoma. This PROM could be integrated into contemporary practice to provide patient-centred outcomes assessment for this patient group, aligning more closely with patient objectives.

A Novel Intraoperative Ultrasound Probe for Transsphenoidal Surgery: First-in-human study.

Background. Ultrasound has been explored as an alternative, less bulky, less time-consuming and less expensive means of intraoperative imaging in pituitary surgery. However, its use has been limited by the size of its probes relative to the transsphenoidal corridor. We developed a novel prototype that is more slender than previously reported forward-viewing probes and, in this report, we assess its feasibility and safety in an initial patient cohort. Method. The probe was integrated into the transsphenoidal approach in patients with pituitary adenoma, following a single-centre prospective proof of concept study design, as defined by the Innovation, Development, Exploration, Assessment and Long-Term Study (IDEAL) guidelines for assessing innovation in surgery (IDEAL stage 1 - Idea phase). Results. The probe was employed in 5 cases, and its ability to be used alongside the standard surgical equipment was demonstrated in each case. No adverse events were encountered. The average surgical time was 20 minutes longer than that of 30 contemporaneous cases operated without intraoperative ultrasound. Conclusion. We demonstrate the safety and feasibility of our novel ultrasound probe during transsphenoidal procedures to the pituitary fossa, and, as a next step, plan to integrate the device into a surgical navigation system (IDEAL Stage 2a - Development phase).

Midline sacral meningeal cyst decompression and repair.

BACKGROUND: Symptomatic midline sacral meningeal cysts (MSMC) are rare, and, as a consequence, so are reports on the surgical techniques to address these lesions. Here we provide a description of the senior author's (ATC) technique. METHOD: A sacral laminectomy is performed. The cyst's relation with the dural sac and sacral nerves is inspected; it is then opened and drained. Its lumen is explored for its point of communication with the dural sac, and this ostium is closed off with non-penetrating clips. A lumbar drain is inserted in select cases. CONCLUSION: Cyst wall resection is unnecessary and closing the ostium is sufficient to treat MSMC.

Intraoperative monitoring of visual evoked potentials in patients undergoing transsphenoidal surgery for pituitary adenoma: a systematic review.

BACKGROUND: Transsphenoidal surgery is the gold standard for pituitary adenoma resection. Although rare, a serious complication of surgery is worsened vision post-operatively. OBJECTIVE: To determine whether, in patients undergoing transsphenoidal surgery for pituitary adenoma, intraoperative monitoring of visual evoked potentials (VEP) is a safe, reproducible, and effective technological adjunct in predicting postoperative visual function. METHODS: The PubMed and OVID platforms were searched between January 1993 and December 2020 to identify publications that (1) featured patients undergoing transsphenoidal surgery for pituitary adenoma, (2) used intraoperative optic nerve monitoring with VEP and (3) reported on safety or effectiveness. Reference lists were cross-checked and expert opinion sought to identify further publications. RESULTS: Eleven studies were included comprising ten case series and one prospective cohort study. All employed techniques to improve reliability. No safety issues were reported. The only comparative study included described a statistically significant improvement in post-operative visual field testing when VEP monitoring was used. The remaining case-series varied in conclusion. In nine studies, surgical manipulation was halted in the event of a VEP amplitude decrease suggesting a widespread consensus that this is a warning sign of injury to the anterior optic apparatus. CONCLUSIONS: Despite limited and low-quality published evidence regarding intra-operative VEP monitoring, our review suggests that it is a safe, reproducible, and increasingly effective technique of predicting postoperative visual deficits. Further studies specific to transsphenoidal surgery are required to determine its utility in protecting visual function in the resection of complex pituitary tumours.

Accuracy of bolt external ventricular drain insertion by neurosurgeons of different experience.

OBJECTIVE: The accuracy of tunneled external ventricular drain (EVD) placement has been shown to be similar among practitioners of varying experience, but this has not yet been investigated for bolt EVDs. Tunneled and bolt EVDs are distinct techniques, and it is unclear if conclusions regarding accuracy can be inferred from one method to the other. The goal of this study was to determine whether neurosurgical experience influences the accuracy of bolt EVD placement. METHODS: We performed a single-center retrospective analysis of accuracy of bolt EVD placement between 1st December 2018 and 31st May 2020, comparing the accuracy outcomes between three levels of training (junior trainees (JT); mid-grade trainees (MT); senior trainees/fellows (ST)). Accuracy was determined radiologically by two methods: Kakarla grade and by measuring the distance of the catheter tip to its optimal position (DTOP) at the foramen of Monro. RESULTS: Eighty-seven patients underwent insertion of bolt EVDs, of which n = 19 by JT, n = 40 by MT and n = 28 by ST, with a significant difference found between training grades in the median Kakarla grade (p = 0.0055) and in the accuracy of placement as per DTOP (p = 0.0168). CONCLUSIONS: In contrast to previous published results on tunneled EVDs, we demonstrate that the accuracy of bolt EVD placement is dependent on neurosurgical experience. Our results draw awareness to the fact that the bolt EVD technique can represent a challenge for less experienced practitioners and underline the importance of dedicated training to support the safe insertion of bolt ventricular catheters.

CSF rhinorrhoea after endonasal intervention to the anterior skull base (CRANIAL): proposal for a prospective multicentre observational cohort study.

BACKGROUND: The endonasal transsphenoidal approach (TSA) has emerged as the preferred approach in order to treat pituitary adenoma and related sellar pathologies. The recently adopted expanded endonasal approach (EEA) has improved access to the ventral skull base whilst retaining the principles of minimally invasive surgery. Despite the advantages these approaches offer, cerebrospinal fluid (CSF) rhinorrhoea remains a common complication. There is currently a lack of comparative evidence to guide the best choice of skull base reconstruction, resulting in considerable heterogeneity of current practice. This study aims to determine: (1) the scope of the methods of skull base repair; and (2) the corresponding rates of postoperative CSF rhinorrhoea in contemporary neurosurgical practice in the UK and Ireland. METHODS: We will adopt a multicentre, prospective, observational cohort design. All neurosurgical units in the UK and Ireland performing the relevant surgeries (TSA and EEA) will be eligible to participate. Eligible cases will be prospectively recruited over 6 months with 6 months of postoperative follow-up. Data points collected will include: demographics, tumour characteristics, operative data), and postoperative outcomes. Primary outcomes include skull base repair technique and CSF rhinorrhoea (biochemically confirmed and/or requiring intervention) rates. Pooled data will be analysed using descriptive statistics. All skull base repair methods used and CSF leak rates for TSA and EEA will be compared against rates listed in the literature. ETHICS AND DISSEMINATION: Formal institutional ethical board review was not required owing to the nature of the study - this was confirmed with the Health Research Authority, UK. CONCLUSIONS: The need for this multicentre, prospective, observational study is highlighted by the relative paucity of literature and the resultant lack of consensus on the topic. It is hoped that the results will give insight into contemporary practice in the UK and Ireland and will inform future studies.

Neuronavigation-assisted bedside placement of bolt external ventricular drains in the intensive care setting: a technical note.

BACKGROUND: The insertion of bolt external ventricular drains (EVD) on the intensive care unit (ICU) has enabled rapid cranial cerebrospinal fluid (CSF) diversion. However, bolt EVDs tend to be perceived as a more challenging technique, particularly when dealing with small ventricles or when there is midline shift distorting the ventricular morphology. Furthermore, if neuronavigation guidance is felt to be necessary, this usually assumes a transfer to an operating theatre. In this technical note, we describe the use of electromagnetic neuronavigation for bolt EVD insertion on the ICU and assess the protocol's feasibility and accuracy. METHODS: Case series of neuronavigation-assisted bolt EVD insertion in ICU setting, using Medtronic Flat Emitter for StealthStation EM. RESULTS: Neuronavigation-guided bolt EVDs were placed at the bedside in n = 5 patients on ICU. Their widest frontal ventricular horn diameter in the coronal plane ranged from 11 to 20 mm. No procedural complications were encountered. Post-procedural CT confirmed the optimal placement of the EVDs. CONCLUSIONS: Electromagnetic neuronavigation is feasible at the ICU bedside and can assist the insertion of bolt EVDs in this setting. The preference for a bolt EVD to be inserted in ICU-as is standard practice at this unit-should not prohibit patients from benefitting from image guidance if required.

Endoscopic endonasal intracanalicular optic nerve decompression: how I do it.

BACKGROUND: The endoscopic endonasal approach for optic nerve decompression is suited for the management of non-traumatic optic neuropathy but remains underreported, presumably due to transcranial approaches still being favoured at individual centres. METHOD: The optic canal is approached endoscopically and transsphenoidally through the contralateral nostril. Its inferomedial wall is opened using an irrigated diamond drill, and neuronavigation is used to confirm anatomical bearings. CONCLUSION: This technique provides rapid and easy access to the inferomedial aspect of the optic canal and nerve. Optic nerve decompression through this approach is associated with low morbidity and should be considered as an alternative to transcranial approaches.

Intraoperative monitoring with visual evoked potentials for brain surgeries.

OBJECTIVE: The goal of this study was to determine the performance of intraoperative visual evoked potentials (VEPs) in detecting visual field changes. METHODS: Assessments of VEPs were performed with simultaneous retinal responses by using white light-emitting diodes protected from scialytic microscope lights. The alarm criterion was a reproducible decrease in amplitude of the VEP P100 wave of 20% or more. Visual fields were assessed preoperatively and 1 month postsurgery (Goldmann perimetry). RESULTS: The VEPs were analyzed for 29 patients undergoing resection of a brain lesion. In 89.7% of patients, steady VEP and retinal responses were obtained for monitoring. The absence of alarm was associated in 94.4% of cases with the absence of postoperative visual changes (specificity). The alarms correctly identified 66.7% of cases with any postoperative changes and 100% of cases with changes more severe than just a discrete quadrantanopia or deterioration of an existing quadrantanopia (sensitivity, new diffuse deterioration < 2 dB). In 11.5% of patients, a transitory VEP decrease with subsequent recovery was observed without postoperative defects. CONCLUSIONS: Intraoperative VEPs were performed with simultaneous recording of electroretinograms, with protection from lights of the operating room and with white light-emitting diodes. Intraoperative VEPs were shown to be reliable in predicting postoperative visual field changes. In this series of intraaxial brain procedures, reliable intraoperative VEP monitoring was achieved, allowing at minimum the detection of new quadrantanopia. The standardization of this technique appears to be a valuable effort in regard to the functional risks of homonymous hemianopia.

Corpus callosotomy.

BACKGROUND: Corpus callosotomy is an effective, relatively low-risk, palliative procedure for a selected population of patients with medically intractable epilepsy. Here we describe this technique. METHOD: An interhemispheric microsurgical approach is performed. Neuronavigation facilitates orientation. The callosal body is transected through to the roof of the ipsilateral ventricle using an ultrasonic aspirator; the genu and rostrum are then identified and also split. If a total callosotomy is performed, transection of the splenium is performed with care given to preserve the crus of the fornix. CONCLUSIONS: Meticulous microsurgical technique and knowledge of the limbic system's anatomy is essential to keeping this procedure safe and effective.

Anterior temporal lobectomy.

BACKGROUND: Anterior temporal lobectomy is the most established neurosurgical procedure for temporal lobe epilepsy. Here we describe this technique. METHOD: A temporal craniotomy is performed flush with the middle fossa and exposing the Sylvian fissure. The posterior extent of resection is determined as 4.5 cm in the dominant temporal lobe and 5.5 cm in the nondominant one. The first stage consists of removing the lateral neocortex and part of the fusiform gyrus, parallel to the Sylvian fissure, while keeping the temporal horn as the medial limit in the coronal plane. Then, the amygdala, uncus, fimbriae, hippocampus and collateral eminence are identified, transected and resected with the parahippocampal gyrus to complete the procedure. CONCLUSION: Knowledge of the temporomesial anatomy, including neurovascular structures around the brainstem, is essential to keep this procedure safe and effective.

Right insular damage decreases heartbeat awareness and alters cardio-visual effects on bodily self-consciousness.

Recent evidence suggests that multisensory integration of bodily signals involving exteroceptive and interoceptive information modulates bodily aspects of self-consciousness such as self-identification and self-location. In the so-called Full Body Illusion subjects watch a virtual body being stroked while they perceive tactile stimulation on their own body inducing illusory self-identification with the virtual body and a change in self-location towards the virtual body. In a related illusion, it has recently been shown that similar changes in self-identification and self-location can be observed when an interoceptive signal is used in association with visual stimulation of the virtual body (i.e., participants observe a virtual body illuminated in synchrony with their heartbeat). Although brain imaging and neuropsychological evidence suggest that the insular cortex is a core region for interoceptive processing (such as cardiac perception and awareness) as well as for self-consciousness, it is currently not known whether the insula mediates cardio-visual modulation of self-consciousness. Here we tested the involvement of insular cortex in heartbeat awareness and cardio-visual manipulation of bodily self-consciousness in a patient before and after resection of a selective right neoplastic insular lesion. Cardio-visual stimulation induced an abnormally enhanced state of bodily self-consciousness; in addition, cardio-visual manipulation was associated with an experienced loss of the spatial unity of the self (illusory bi-location and duplication of his body), not observed in healthy subjects. Heartbeat awareness was found to decrease after insular resection. Based on these data we propose that the insula mediates interoceptive awareness as well as cardio-visual effects on bodily self-consciousness and that insular processing of interoceptive signals is an important mechanism for the experienced unity of the self.

Augmented reality-assisted bypass surgery: embracing minimal invasiveness.

OBJECTIVE: The overlay of virtual images on the surgical field, defined as augmented reality, has been used for image guidance during various neurosurgical procedures. Although this technology could conceivably address certain inherent problems of extracranial-to-intracranial bypass procedures, this potential has not been explored to date. We evaluate the usefulness of an augmented reality-based setup, which could help in harvesting donor vessels through their precise localization in real-time, in performing tailored craniotomies, and in identifying preoperatively selected recipient vessels for the purpose of anastomosis. METHODS: Our method was applied to 3 patients with Moya-Moya disease who underwent superficial temporal artery-to-middle cerebral artery anastomoses and 1 patient who underwent an occipital artery-to-posteroinferior cerebellar artery bypass because of a dissecting aneurysm of the vertebral artery. Patients' heads, skulls, and extracranial and intracranial vessels were segmented preoperatively from 3-dimensional image data sets (3-dimensional digital subtraction angiography, angio-magnetic resonance imaging, angio-computed tomography), and injected intraoperatively into the operating microscope's eyepiece for image guidance. RESULTS: In each case, the described setup helped in precisely localizing donor and recipient vessels and in tailoring craniotomies to the injected images. CONCLUSIONS: The presented system based on augmented reality can optimize the workflow of extracranial-to-intracranial bypass procedures by providing essential anatomical information, entirely integrated to the surgical field, and help to perform minimally invasive procedures.