Pilot Validation of a 3-Dimensional Printed Pituitary Adenoma, Vascular Injury, and Cerebrospinal Fluid Leak Surgical Simulator.

BACKGROUND AND OBJECTIVES: Endoscopic skull base surgery is a subspecialty field which would benefit significantly from high-fidelity surgical simulators. Giving trainees the opportunity to flatten their learning curve by practicing a variety of procedures on surgical simulators will inevitably improve patient outcomes. METHODS: Four neurosurgeons, 8 otolarynologists, and 6 expert course faculty agreed to participate. All participants were asked to perform a transsphenoidal exposure and resection of a pituitary adenoma, repair a cerebrospinal fluid (CSF) leak, control a carotid injury, and repair a skull base defect. The content, face, and construct validity of the 3-dimensional printed model was examined. RESULTS: The heart rate of the participants significantly increased from baseline when starting the carotid injury simulation (mean 90 vs 121, P = .029) and significantly decreased once the injury was controlled (mean 121 vs 110, P = .033, respectively). The participants reported a significant improvement in anxiety in facing a major vascular injury, as well as an increase in their confidence in management of major vascular injury, resecting a pituitary adenoma and repair of a CSF leak using a 5-point Likert scale (mean 4.42 vs 3.58 P = .05, 2 vs 3.25 P < .001, 2.36 vs 4.27 P < .001 and 2.45 vs 4.0 P = .001, respectively). The mean Objective Structured Assessment of Technical Skills score for experienced stations was 4.4, significantly higher than the Objective Structured Assessment of Technical Skills score for inexperienced stations (mean 3.65, P = .016). CONCLUSION: We have demonstrated for the first time a validated 3-dimensional printed surgical simulator for endoscopic pituitary surgery that allows surgeons to practice a transsphenoidal approach, surgical resection of a pituitary adenoma, repair of a CSF leak in the diaphragma sellae, control of a carotid injury, and repair of skull base defect.

Neuronavigation in endoscopic skull base surgery and the accuracy of different MRI sequences.

OBJECTIVE: Neuronavigation is common technology used by skull base teams when performing endoscopic endonasal surgery. A common practice of MRI imagining is to obtain 3D isotopic gadolinium enhanced T1W magnetisation prepared rapid gradient echo (MPRAGE) sequences. These are prone to distortion when undertaken on 3 T magnets. The aim of this project is to compare the in vivo accuracy of MRI sequences between current and new high resolution 3D sequences. The goal is to determine if geometric distortion significantly affects neuronavigation accuracy. METHODS: Patients were scanned with a 3D T1 MPRAGE sequence, 3D T1 SPACE sequence and a CT stereotactic localisation. Following general anaesthesia, patients were registered on the Stealth Station (Medtronic, USA) using a side mount emitter for Electromagnetic navigation. A variety of surgically relevant anatomical landmarks in the sagittal and coronal plane were selected with real and virtual data points measured. RESULTS: A total of 10 patients agreed be enrolled in the study with datapoints collected during surgery. The distance between real and virtual datapoints trended to be lower in SPACE sequences compared to MPRAGE. Paired t test did not demonstrate a significant difference. CONCLUSION: We have demonstrated that navigational accuracy is not significantly affected by the type of MRI sequence selected and that current corrective algorithms are sufficient. Navigational accuracy is affected by many factors, with registration error likely playing the most significant role. Further research involving real time imaging such as endoscopic ultrasound may hopefully address this potential error.

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.

Transorbital drillout to the cavernous sinus: an approach for squamous cell carcinoma with perineural spread. Illustrative cases.

BACKGROUND: This study describes a transorbital apical approach to the cavernous sinus, where the greater wing of sphenoid (GWS) and superior orbital fissure (SOF) are drilled out to access the interdural incision zone and lateral wall of the cavernous sinus. OBSERVATIONS: This was a retrospective series of 3 patients with periocular squamous cell carcinoma (SCC) and radiological evidence of perineural spread to the cavernous sinus. Following an orbital exenteration, the GWS was drilled to reach the lateral border of the SOF. The meningo-orbital band, a periosteal transition between the frontotemporal basal dura and periorbita, was incised to enter the lateral wall of the cavernous sinus. The relevant cranial nerves were biopsied to provide an accurate zonal classification of disease. LESSONS: The transorbital apical approach via the SOF provides a corridor of access to the cranial nerves within the lateral wall of the cavernous sinus. This technique was successfully performed on 3 patients with periocular SCC. One case had radiological evidence of intracavernous oculomotor nerve involvement, 1 patient demonstrated nasociliary nerve enlargement at the SOF, and another had frontal nerve involvement extending into the cavernous sinus. Cerebrospinal fluid leak occurred in 1 case addressed with fat packing and fascial closure.

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.

Update on endoscopic endonasal resection of skull base meningiomas.

BACKGROUND: The objective of this work was to report success rates as well as potential obstacles in transnasal endoscopic resection of anterior skull base meningiomas. METHODS: The study design was a case series with chart review at tertiary referral centers in South Australia and New Zealand. The patients were 37 consecutive patients who underwent endoscopic resection of skull-base meningiomas between 2004 and 2013. Review of patient charts and operative details were performed. Outcomes including complications are reported. RESULTS: Eighty-four percent of patients were women. There were 28 primary and 9 revision cases. Tumor locations were as follows: 14 olfactory groove/subfrontal; 12 planum/jugum sphenoidale; 7 tuberculum sellae; 3 clinoidal; and 1 clival. Vision change was the most common presenting symptom. Mean tumor volume was 33.68 cm(3) , mean diameter was 2.78 cm. Average operating times decreased with an initial learning curve and then plateaued. Primary tumors larger than 60 cm(3) took an average of 10 hours to resect. Gross total removal was achieved in 29 patients. There were no perioperative deaths. Two deaths occurred within 1 year of surgery. Postoperative cerebrospinal fluid (CSF) leaks occurred in 13 patients. Seventy-five percent of patients presenting with visual loss reported visual improvement. Of the 29 patients considered to have had complete resection at surgery, one was found to have residual disease on a postoperative magnetic resonance imaging (MRI) and another one later developed radiological evidence of recurrence. CONCLUSION: Using a 2-team approach, meningiomas of the skull base were successfully removed via an intranasal endoscopic technique. Although complete resection is typically possible even with large tumors, the lengthy resection required time for tumors larger than 60 cm(3) (diameter ≥4 cm) may obviate some of the advantages of this approach. The rate of postoperative CSF leak decreases when a synthetic dural substitute is added but does not approach zero.

Endoscopic endonasal resection of anterior skull base meningiomas.

OBJECTIVE: Anterior cranial fossa (ACF) meningiomas are difficult to surgically manage. Endoscopic transnasal approaches have increasingly been used as a minimally invasive route and thus offer significant advantages. However, a paucity of literature describing the intraoperative challenges and postoperative outcomes of this technique still exists. STUDY DESIGN: Case series with chart review. SETTING: The Royal Adelaide Hospital, Flinders Medical Centre, Wellington Hospital. SUBJECTS AND METHODS: Fifteen consecutive patients who underwent endoscopic resection of ACF meningiomas between 2004 and 2010 by the South Australian and Wellington Skull Base Units. Demographic and clinical information was compiled by reviewing patient charts and operation notes. Safety and efficacy of the procedure, role of a team approach, and areas for further improvement were analyzed. RESULTS: Of the patients, 87% were women. Tumor locations: 8 olfactory groove, 2 tuberculum sellae, 1 clinoidal, 1 jugum sphenoidale, 1 planum sphenoidale, 1 subfrontal, and 1 midline ACF floor. Commonest presenting symptom was visual change. Mean volume of tumor was 25.69 cm(3), with a size area of 7.28 cm(2). Five were revision cases. None had previous endonasal surgery. Average operating times decreased over time. Gross total removal was achieved in 14, with no deaths. Four patients had postoperative cerebrospinal fluid (CSF) leak. Rate of CSF leak decreased over time. Sixty percent of patients reported visual improvement. Two patients had radiological evidence of recurrence. CONCLUSION: ACF meningiomas can be safely removed endonasally, offering significant advantages over the traditional transcranial approach for suitable tumors. Early audit of this approach shows results achieved by this unit are comparable with the published literature.

Endoscopic surgery of skull base chordomas.

Objective To assess our clinical experience in treating midline intracranial pathology using minimally invasive surgical techniques. Design Retrospective chart review of patients undergoing endoscopic endonasal resection of clival chordomas. Setting Two tertiary referral centers in Australia and New Zealand. Main Outcome Measures Patients were assessed by intraoperative findings (macroscopic resection rate, tumor size, and operative complications) and clinical outcomes (residual disease, postoperative complications, recurrence rate, and mortality). Results Fourteen patients underwent endoscopic resection of clival chordomas (seven primary, seven revision) with a mean follow-up of 41.45 months (3 to 104 months). Macroscopic resection rates were 71% and 29%, respectively. Mean operative time was 386 minutes. Overall cerebrospinal fluid (CSF) leak rate was 3/14 (21%) and, using the nasoseptal flap, it was 0/5 (0%). Two patients developed late recurrence; one died of disease and one was treated with intensity modulated radiation therapy. Overall mortality was 2/14 (14%). Conclusion Endoscopic resection of clival chordomas is a safe and viable alternative to the traditional open approach. The nasoseptal flap is an excellent method of obtaining a watertight skull base closure. Furthermore, this series highlighted the fact that the primary attempt at surgery offers the best chance to achieve a total resection.

A novel use of temozolomide in a patient with malignant prolactinoma.

We report a 64-year-old male who presented to our department in 2007 with bitemporal hemianopia secondary to a large recurrent pituitary prolactinoma in the sellar region and metastatic deposits elsewhere in his neuraxis. He underwent a transphenoidal excision of the large pituitary adenoma which was uncomplicated, although he did suffer from diabetes insipidus post-operatively. He had initially been diagnosed with prolactinoma some years before and had undergone multiple craniotomies to debulk recurrent metastatic lesions. As the patient had already undergone radiotherapy in the past, a novel approach to adjuvant therapy was necessary and he was started on a course of oral chemotherapy, temozolomide, with good results.

Fully endoscopic transsphenoidal resection of pituitary tumors: technique and results.

BACKGROUND: The aim of this study was to describe our two-surgeon fully endoscopic approach to pituitary surgery and to report results in terms of tumor remission, improvement in vision, and complications. A retrospective chart review was performed. METHODS: Our prospectively recorded surgical database was searched for all endoscopic transsphenoidal procedures between January 2001 and December 2005. Those patients who had surgery had their medical charts reviewed and presenting symptoms and signs, lesion characteristics, endocrine investigations, operative details, complications, and treatment outcomes recorded. RESULTS: Thirty-two patients were included in the study. Twenty-three patients had macroadenomas, five patients had microadenomas, and four patients had other pathologies. Most patients with macroadenomas had significant supra- or parasellar extension. Of the 14 patients who had visual loss at presentation, 13 had postoperative improvement. Two patients had postoperative cerebrospinal fluid leaks, which were successfully treated endoscopically. Eight patients required some form of hormone replacement after surgery. After a mean follow-up of 31 months, the overall remission rate for patients with macroadenomas was 82% and for patients with microadenomas was 100%. CONCLUSION: The fully endoscopic transsphenoidal approach provides excellent visualization for tumor resection and results in acceptable remission rates.