The Learning Curve for Endoscopic Endonasal Transsphenoidal Pituitary Surgery: Evaluating Endocrine Outcomes

OBJECTIVE

In South Australia endoscopic endonasal approach (EEA) pituitary surgery has been practiced since 2006, largely by two neurosurgeons with a small fellowship-trained otolaryngology team. The aim of this cohort study was to determine if a "learning curve" can be established over this time period, as represented by structural and endocrine patient outcomes.

METHOD

Retrospective cohort study of patients undergoing EEA surgery between 2006 and 2021 in Adelaide, South Australia at three tertiary teaching hospitals.. Cases were divided by each surgeon and split into groups of sequential 40 cases. Endocrine assessment pre- and post-operatively involved static pituitary and end-organ hormones, with dynamic tests as required, assessed by an pituitary endocrinologist. Each hormonal axis (gonadal, cortisol, thyroid, prolactin and growth hormone) was documented preoperatively and at an early and long term follow up at 1-2 and 12 months, respectively.

RESULTS

The study included a cohort of 443 pituitary adenomas managed with endoscopic endonasal transsphenoidal surgery in a consecutive fashion between two neurosurgeons over 16-years. Gross tumour resection but not visual visual outcomes improved with surgical experience but this outcome may be neurosurgeon dependent. Endocrine outcomes were not consistently improved with experience, but lower rates of hypopituitarism were seen with experience with one neurosurgeon. Average follow up was approximately 5 years, and a minimum follow up of 12 months for all patients.

CONCLUSIONS

We present long term endocrine follow up for patients with functional and non-functional adenomas. Improved rates of gross tumour resection were evident with with surgical experience. However, there was no apparent change in post-operative endocrine outcomes.

Clipping of a persistent middle cerebral artery aneurysm after previous flow diverter placement: An illustrative case and review of the literature

Flow diverter (FD) is increasingly used in the management of wide necked cerebral aneurysms. Despite a reported lower efficacy in middle cerebral artery (MCA) aneurysms, they are still being utilised. Microsurgery is best considered as an index treatment, but can also be a safe and effective treatment when encountering a persistent MCA aneurysm after prior FD. As there is a paucity in literature and more cases of failed FD are expected to appear, we want to add our experience to the existing literature. The microsurgical management of a persistent MCA bifurcation aneurysm, 3 years after a p48 MW HPC Flow Diverter (phenox GmbH, Bochum Germany) insertion is reported and the relevant literature discussed.

'What's in a name', a systematic review of the pterional craniotomy for aneurysm surgery and its many modifications with a proposal for simplified nomenclature

BACKGROUND

The pterional or frontosphenotemporal craniotomy has stood the test of time and continues to be a commonly used method of managing a variety of neurosurgical pathology. Already described in the beginning of the twentieth century and perfected by Yasargil in the 1970s, it has seen many modifications. These modifications have been a normal evolution for most neurosurgeons, tailoring the craniotomy to the patients' specific anatomy and pathology. Nonetheless, an abundance of variations have appeared in the literature.

METHODS

A search strategy was devised according to the 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. To identify articles investigating the variations in the pterional approach, the following search terms were applied: (pterional OR minipterional OR supraorbital) AND (approach OR craniotomy OR technique).

RESULTS

In total, 3552 articles were screened with 74 articles being read in full with 47 articles being included for review. Each article was examined according the name of the technique, temporalis dissection technique, craniotomy technique and approach.

CONCLUSION

This systematic review gives an overview of the different techniques and modifications to the pterional craniotomy since it was initially described. We advocate for the use of a more standardised nomenclature that focuses on the target zone to simplify the management approach to supratentorial aneurysms.

Imaging evaluation of a proposed 3D generative model for MRI to CT translation in the lumbar spine

BACKGROUND CONTEXT

A computed tomography (CT) and magnetic resonance imaging (MRI) are used routinely in the radiologic evaluation and surgical planning of patients with lumbar spine pathology, with the modalities being complimentary. We have developed a deep learning algorithm which can produce 3D lumbar spine CT images from MRI data alone. This has the potential to reduce radiation to the patient as well as burden on the health care system.

PURPOSE

The purpose of this study is to evaluate the accuracy of the synthetic lumbar spine CT images produced using our deep learning model.

STUDY DESIGN

A training set of 400 unpaired CTs and 400 unpaired MRI scans of the lumbar spine was used to train a supervised 3D cycle-Gan model. Evaluators performed a set of clinically relevant measurements on 20 matched synthetic CTs and true CTs. These measurements were then compared to assess the accuracy of the synthetic CTs.

PATIENT SAMPLE

The evaluation data set consisted of 20 patients who had CT and MRI scans performed within a 30-day period of each other. All patient data was deidentified. Notable exclusions included artefact from patient motion, metallic implants or any intervention performed in the 30 day intervening period.

OUTCOME MEASURES

The outcome measured was the mean difference in measurements performed by the group of evaluators between real CT and synthetic CTs in terms of absolute and relative error.

METHODS

Data from the 20 MRI scans was supplied to our deep learning model which produced 20 "synthetic CT" scans. This formed the evaluation data set. Four clinical evaluators consisting of neurosurgeons and radiologists performed a set of 24 clinically relevant measurements on matched synthetic CT and true CTs in 20 patients. A test set of measurements were performed prior to commencing data collection to identify any significant interobserver variation in measurement technique.

RESULTS

The measurements performed in the sagittal plane were all within 10% relative error with the majority within 5% relative error. The pedicle measurements performed in the axial plane were considerably less accurate with a relative error of up to 34%.

CONCLUSIONS

The computer generated synthetic CTs demonstrated a high level of accuracy for the measurements performed in-plane to the original MRIs used for synthesis. The measurements performed on the axial reconstructed images were less accurate, attributable to the images being synthesized from nonvolumetric routine sagittal T1-weighted MRI sequences. It is hypothesized that if axial sequences or volumetric data were input into the algorithm these measurements would have improved accuracy.

Randomized Trial Comparing Burr Hole Craniostomy, Minicraniotomy, and Twist Drill Craniostomy for Treatment of Chronic Subdural Hematoma

BACKGROUND

The mainstay of treatment for symptomatic or large chronic subdural hematoma (CSDH) is surgery, but controversy still exists regarding the best surgical technique. Three different techniques are commonly used: burr hole craniostomy (BHC), minicraniotomy (MC), and twist drill craniostomy (TDC).

OBJECTIVE

To determine which surgical technique for drainage of CSDH offers best results.

METHODS

We set up a multicenter prospective randomized trial (Comparison of Chronic Subdural Hematoma Treatment [COMPACT] trial) comparing BHC, MC, and TDC for the surgical treatment of CSDH. The primary end point was reoperation rate, and secondary end points included complication rates and clinical outcome. Patients were considered to have good outcome when they did not undergo reoperation, suffered no surgical or medical complication, and had no related mortality. Clinical outcome was also evaluated by evolution of the Markwalder score and the modified Rankin score.

RESULTS

Two-hundred forty-five patients were included in the final analysis: 79 BHC, 84 MC, and 82 TDC. Mean duration of surgery was shorter for TDC than for BHC and MC (P < .001). Reoperation rate was 7.6% for BHC, 13.1% for MC, and 19.5% for TDC (P = .07). This trend toward better results for BHC was not statistically significant in logistic regression analysis. The proportion of patients with good outcome was 78.5% for BHC group, 76.2% for MC, and 69.5% for TDC (P = .4). Evolution of the Markwalder score and modified Rankin score were not significantly different between treatment groups.

CONCLUSION

All 3 techniques are effective at treating patients with CSDH with eventual 6-month outcome being similar. Although not reaching statistical significance in our study, BHC offers the lowest recurrence rate combined with manageable complication rate.

Aneurysmal subarachnoid haemorrhage in Indigenous and non-Indigenous Australians: A retrospective study assessing patient characteristics and outcome

INTRODUCTION

Smoking and hypertension are prevalent among Indigenous Australians (Aboriginal and Torres Strait Islanders). We investigated if these risk factors suggest a greater rate of aneurysmal subarachnoid haemorrhage in Indigenous Australians (IA) compared to non-IA.

MATERIALS AND METHODS

A retrospective cross-sectional study was performed on data retrieved from the Nationwide Hospital Morbidity Database for all aSAH cases in Australia between 2012 and 2018. Patient characteristics, radiological findings, aneurysm characteristics, treatment characteristics and discharge outcomes were assessed. Crude and age-adjusted incidences, trends of aSAH and case fatality rate over time were calculated.

RESULTS

A total of 12,286 patients were included (285 IA, 12,001 non-IA). Indigenous aSAH patients were significantly younger than non-IA, with 89.8 percent of IA younger than 65 years old (p < 0.001). Crude annual incidences were similar between the 2 cohorts, however age-adjusted incidence shows a RR = 1.4 at 45-59 years in IA patients, compared with their non-IA counterparts. 30-day mortality was similar between the two groups, at 25.3 and 26.9% for IA and non-IA groups, respectively.

CONCLUSION

This 10 year nationwide retrospective study highlights a disparity between the crude and age-adjusted incidence of aSAH in IA compared to non-IA.

Pituitary carcinoma - case series and review of the literature

Although pituitary adenomas (PAs) account for 15% of intracranial tumors, pituitary carcinomas (PCs) are a rare entity. Most commonly, PCs evolve from aggressive PAs invading the surrounding structures and eventually leading to metastatic lesions. Due to the low incidence, the diagnosis and treatment remains challenging. We report a case series of five patients with pituitary carcinoma (PC) treated in our center. At first diagnosis 3 patients had an ACTH-producing adenoma, 1 a prolactinoma and 1 a double secreting adenoma (GH and prolactin). The mean time interval from initial diagnosis to diagnosis of PC was 10.7 years (range 5-20 years). All patients underwent multiple surgical resections and radiotherapy. Four patients were treated with temozolomide for metastatic disease. One patient with concomitant radiochemotherapy for local recurrence. Temozolomide led to a stable disease in 2 patients. One patient had a progressive disease after 9 cycles of temozolomide. In absence of standard treatment, immunotherapy was initiated, resulting in a stable disease. We report five cases of PCs. Three patients obtained a stable disease after tailored multidisciplinary treatment. Additionally, one patient was treated with immunotherapy, opening a new treatment option in PCs. Overall, PCs are rare intracranial neoplasms occurring several years after the initial diagnosis of aggressive PAs. Currently, the absence of predictive factors for an aggressive clinical course, provokes a challenging management.

Syringomyelia intermittens: highlighting the complex pathophysiology of syringomyelia. Illustrative case

BACKGROUND

Chiari Type I malformation (CM1) is a disorder recognized by caudal displacement of the cerebellar tonsils through the foramen magnum and into the cervical canal. Syringomyelia is frequently found in patients with CM1, but the pathophysiology of syringomyelia remains an enigma. As a general consensus, symptomatic patients should be treated and asymptomatic patients without a syrinx should not be treated. Mildly symptomatic patients or asymptomatic patients with a syrinx, on the other hand, pose a more challenging dilemma, as the natural evolution is uncertain. For many surgeons, the presence of a syrinx is an indication to offer surgery even if the patient is asymptomatic or mildly symptomatic.

OBSERVATIONS

The authors describe an illustrative case of a 31-year-old female with an incidental finding of a CM1 malformation and cervical syrinx in 2013. Conservative management was advocated as the patient was asymptomatic. Monitoring of the syrinx over a course of 8 years showed resolution, followed by reappearance and finally a complete resolution in 2021. A review of the literature and the possible pathophysiology is discussed.

LESSONS

The unusual course of this patient highlights the importance of guiding treatment by clinical symptoms, not radiological findings. Furthermore it reflects the complexity of the pathophysiology and the uncertain natural history of syringomyelia.

Management of an Internal Carotid Artery Injury During Open Skull Base Surgery With a Crushed Muscle Patch - Technical Note and Lessons Learned

BACKGROUND

Iatrogenic internal carotid artery (ICA) injury is a catastrophic complication in open skull base surgery. There is a lack of information regarding the most appropriate techniques on how to manage this complication.

OBJECTIVE

To highlight the difficulties encountered when an ICA injury arises intraoperatively and discuss the role and the potential pitfalls of the crushed muscle patch in the management of an ICA injury during open skull base surgery.

METHODS

In this technical video, we demonstrate the management of intraoperative ICA injury, which occurred during the resection of a diffuse planum sphenoidale meningioma via a left pterional craniotomy.

RESULTS

When isolation of the defect with temporary clips failed, we opted for a crushed muscle graft to plug the defect. Hemostasis was achieved, but because of prolonged pressure application and "overpacking," the parent vessel was occluded.

CONCLUSION

The crushed muscle patch can be easily applied; however, care must be taken not to "overpack" and occlude the ICA.

When the fat hits the brain-salvage STA-MCA bypass for an intracranial ICA occlusion due to a fat embolus

Background

Large fat embolus is a rare but potential reversible cause of ischaemic stroke.

Methods and results

We describe the neurosurgical management of a complete right internal carotid artery occlusion due to a large fat embolus, caused by a mitral valve replacement.

Conclusion

Knowledge of acute cerebral ischaemia due to large fat embolism and its hallmark 'hypodense artery' is mandatory. Extracranial to intracranial bypass is a feasible rescue treatment after failure of endovascular embolectomy.

Kinked Perforator Due to Clipping of Parent Vessel Aneurysm: Technical Note and Lessons Learned

BACKGROUND

Adverse outcomes after aneurysm clipping can be potentially reversible, when managed appropriately.

METHODS

This is a case report describing kinking of a perforator due to clipping of parent vessel aneurysm.

RESULTS

Complete recovery of a high-grade motor deficit was achieved after instant reintervention with application of smaller clips in combination with gelfoam soaked in papaverine.

CONCLUSION

Use of evoked potentials and intraoperative digital subtraction angiography are recommended and may help in preclinical diagnosis. Knowledge of delayed perforator kinking as a complication may lead to a more rapid diagnosis and management.

Posterior approach for anteriorly located cervical spinal cord hemangioblastomas: technical note

The surgical management of anteriorly located spinal cord hemangioblastomas remains a challenge. Different approaches have been published, of which the anterior approach seems to be the most obvious and commonly used. A posterior approach might be more suitable in certain patients, especially in cases of cystic hemangioblastomas. The authors present 3 cases of anterior spinal hemangioblastomas, which were all resected via a posterior approach. The authors discuss the rationale for choosing this approach and explain the technique in detail.

Mini-craniotomy as the primary surgical intervention for the treatment of chronic subdural hematoma--a retrospective analysis

BACKGROUND

The incidence of chronic subdural hematoma (CSDH) is increasing, but optimal treatment remains controversial. Recent meta-analyses suggest burr hole (BH) drainage is the best treatment because it provides optimal balance between recurrence and morbidity. Mini-craniotomy may offer supplementary technical advantages while maintaining equal or better outcomes. This study investigates the outcome of mini-craniotomy as the sole treatment in patients with CSDH.

METHOD

We analyzed all patients operated on for CSDH with mini-craniotomy in our neurosurgical center between 2005-2010. Baseline patient characteristics (age, sex, comorbidities, imaging characteristics, known risk factors for development of CSDH and neurological examination at presentation) and outcomes (mortality, complications, recurrence and neurological examination at discharge) were recorded.

RESULTS

One hundred twenty-six adult patients were included, mean age was 73.9 (range 18 to 95) years old, and the sex ratio (M:F) was 2:1. Eighty-four percent of the patients showed clinical improvement at discharge, as shown by a decrease in the Markwalder score postoperatively (with 57 % Markwalder 0 and 23 % Markwalder 1). Recurrence rate was 8.7 %. Overall complication rate was 34.1 % (27.8 % medical complications and 6.3 % surgical complications). In-hospital mortality was 13.5 % (8.7 % due to pulmonary infections and 1.6 % to surgical complications). Preoperative Markwalder grade correlated significantly with complication rate, as did the presence of a neurodegenerative disease (p = 0.018). Factors significantly related to mortality in univariate analysis were arterial hypertension (p = 0.038), heart failure (p = 0.02), renal failure (p = 0.017), neurodegenerative disease (p = 0.001), cerebrovascular accident (p = 0.008) and coagulopathy (p = 0.019). Multivariate analysis was not able to confirm any significant relationship.

CONCLUSION

This is the first published series of CSDH in which all consecutive patients were operated on by mini-craniotomy. The invasiveness and complication rate of mini-craniotomy are equal to those of burr hole treatment, but visualization is superior, resulting in lower recurrences. A randomized controlled trial is indicated to identify the best surgical strategy for the treatment of CSDH.