Principles of Pituitary Surgery

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Approach to the Sellar and Parasellar Regions

Introduction  Surgery of the sellar and parasellar regions can be challenging due to the complexity of neurovascular relationships. The main goal of this study is to develop an educational resource to help trainees understand the pertinent anatomy and procedural steps of the endoscopic endonasal approaches (EEAs) to the sellar and parasellar regions. Methods  Ten formalin-fixed latex-injected specimens were dissected. Endoscopic endonasal transsphenoidal transsellar, transtuberculum-transplanum, and transcavernous approaches were performed by a neurosurgery trainee, under supervision from the senior authors and a PhD in anatomy with advanced neuroanatomy experience. Dissections were supplemented with representative case applications. Results  Endoscopic endonasal transsphenoidal approaches afford excellent direct access to sellar and parasellar regions. After a wide sphenoidotomy, a limited sellar osteotomy opens the space to sellar region and medial portion of the cavernous sinus. To reach the suprasellar space (infrachiasmatic and suprachiasmatic corridors), a transplanum-prechiasmatic sulcus-transtuberculum adjunct is needed. The transcavernous approach gains access to the contents of the cavernous sinus and both medial (posterior clinoid and interpeduncular cistern) and lateral structures of the retrosellar region. Conclusion  The anatomical understanding and technical skills required to confidently remove skull base lesions with EEAs are traditionally gained after years of specialized training. We comprehensively describe EEAs to sellar and parasellar regions for trainees to build knowledge and improve familiarity with these approaches and facilitate comprehension and learning in both the surgical anatomy laboratory and the operating room.

Evaluation of early postoperative day 1 discharge after endoscopic endonasal pituitary adenoma resection

OBJECTIVE

While multiple studies have evaluated the length of stay after endonasal transsphenoidal surgery (ETS) for pituitary adenoma, the potential for early discharge on postoperative day 1 (POD 1) remains unclear. The authors compared patients discharged on POD 1 with patients discharged on POD > 1 to better characterize factors that facilitate early discharge after ETS.

METHODS

A retrospective chart review was performed for patients undergoing ETS for pituitary adenoma at a single tertiary care academic center from February 2005 to February 2020. Discharge on POD 1 was defined as a discharge within 24 hours of surgery.

RESULTS

A total of 726 patients (mean age 55 years, 52% male) were identified, of whom 178 (24.5%) patients were discharged on POD 1. These patients were more likely to have pituitary incidentaloma (p = 0.001), require dural substitutes and DuraSeal (p = 0.0001), have fewer intraoperative CSF leaks (p = 0.02), and have lower postoperative complication rates (p = 0.006) compared with patients discharged on POD > 1. POD 1 patients also showed higher rates of macroadenomas (96.1% vs 91.4%, p = 0.03) and lower rates of functional tumors (p = 0.02). POD > 1 patients were more likely to have readmission within 30 days (p = 0.002), readmission after 30 days (p = 0.0001), nasal synechiae on follow-up (p = 0.003), diabetes insipidus (DI; 1.7% vs 9.8%, p = 0.0001), postoperative hypocortisolism (21.8% vs 12.1%, p = 0.01), and postoperative steroid usage (44.6% vs 59.7%, p = 0.003). The number of patients discharged on POD 1 significantly increased during each subsequent time epoch: 2005-2010, 2011-2015, and 2016-2020 (p = 0.0001). On multivariate analysis, DI (OR 7.02, 95% CI 2.01-24.57; p = 0.002) and intraoperative leak (OR 2.02, 95% CI 1.25-3.28; p = 0.004) were associated with increased risk for POD > 1 discharge, while operation epoch (OR 0.46, 95% CI 0.3-0.71; p = 0.0001) was associated with POD 1 discharge.

CONCLUSIONS

This study demonstrates that discharge on POD 1 after ETS for pituitary adenomas was safe and feasible and without increased risk of 30-day readmission. On multivariate analysis, surgical epoch was associated with decreased risk of prolonged length of stay, while factors associated with increased risk of prolonged length of stay included DI and intraoperative CSF leak. These findings may help in selecting patients who are deemed reasonable for safe, early discharge after pituitary adenoma resection.

Surgical Outcomes of Endoscopic Transsphenoidal Pituitary Adenoma Resection in Elderly Versus Younger Patients

Introduction  Pituitary adenomas (PAs) are one of the most common types of intracranial neoplasm with increased incidence in elderly patients. The outcomes of endoscopic transsphenoidal surgery (ETS) specifically on elderly patients remain unclear. Methods  We performed a retrospective cohort study to compare elderly patients (age ≥65 years) with nonelderly patients (age <65 years) who underwent ETS for PA from January 2005 to December 2020. Surgical outcomes, including extent of resection, complication profile, length of stay, and endocrinopathy rates, were compared between elderly and nonelderly patients. Results  A total of 690 patients were included, with 197 (29%) being elderly patients. Elderly patients showed higher rates of hypertension ( p  < 0.05), myocardial infarction ( p  < 0.01), and atrial fibrillation ( p  = 0.01) but not other comorbidities. Elderly patients also had more frequent optic nerve involvement (72 vs. 61% of cases, p  = 0.01). Tumor characteristics and other patient variables were otherwise similar between younger and elderly patients. Postoperative cerebrospinal fluid (CSF) leaks (2 vs. 2%, p  = 0.8), 30-day readmission, reoperation, postoperative complications, and postoperative endocrinopathies were similar between younger and older patients. Subdividing patients into age <65, 65 to 79, and >80 years also did not demonstrate a worsening of surgical outcomes with age. Conclusion  For well-selected elderly patients in experienced endoscopic skull base centers, good surgical outcomes similarly to younger patients may be achieved.

Management of Coincident Pituitary Macroadenoma and Cavernous Carotid Aneurysm: A Systematic Literature Review

Introduction  Pituitary adenomas are a common intracranial pathology with an incidence of 15 to 20% in the population while cerebral aneurysms are less common with a prevalence of 1:50 patients. The incidence of aneurysms in patients with pituitary adenoma has been estimated at 2.3 to 5.4% of patients; however, this remains unclear. Equally, the management of concomitant lesions lacks significant understanding. Methods  A case report is presented of a concomitant cerebral aneurysm and pituitary adenoma managed by minimally invasive endovascular and endoscopic methods, respectively. A systematic review of the literature for terms "pituitary adenoma" and "aneurysm" yielded 494 studies that were narrowed to 19 relevant articles. Results  We report a case of a 67-year-old patient with an enlarging pituitary macroadenoma, cavernous carotid aneurysm, and unilateral carotid occlusion. After successful treatment of the aneurysm by a pipeline flow diverter, the pituitary adenoma was surgically resected by an endoscopic transsphenoidal approach. Conclusion  The use of a pipeline flow diverter and endonasal approach was feasible in the treatment of our patient. This is the first report to our knowledge of the use of pipeline flow diversion in the management of a cavernous carotid aneurysm prior to pituitary adenoma treatment.

Predictive Clinical and Surgical Factors Associated with Recurrent Apoplexy in Pituitary Adenomas

Introduction Pituitary apoplexy is an uncommon clinical condition that can require urgent surgical intervention, but the factors resulting in recurrent apoplexy remain unclear. The purpose of this study is to determine the risks of a recurrent apoplexy and better understand the goals of surgical treatment.

Methods A retrospective chart review was performed for all consecutive patients diagnosed and surgically treated for pituitary apoplexy from 2004 to 2021. Univariate analysis was performed to identify risk factors associated with recurrent apoplexy.

Results A total of 115 patients were diagnosed with pituitary apoplexy with 11 patients showing recurrent apoplexy. This occurred at a rate of 2.2 cases per 100 patient-years of follow-up. There were no major differences in demographic factors, such as hypertension or anticoagulation use. There were no differences in tumor locations, cavernous sinus invasion, or tumor volumes (6.84 ± 4.61 vs. 9.15 ± 8.45 cm, p = 0.5). Patients with recurrent apoplexy were less likely to present with headache (27.3%) or ophthalmoplegia (9.1%). Recurrent apoplexy was associated with prior radiation (0.0 vs. 27.3%, p = 0.0001) and prior subtotal resection (10.6 vs. 90.9%, p = 0.0001) compared with first time apoplexy. The mean time to recurrent apoplexy was 48.3 ± 76.9 months and no differences in overall follow-up were seen in this group.

Conclusion Recurrent pituitary apoplexy represents a rare event with limited understanding of pathophysiology. Prior STR and radiation treatment are associated with an increased risk. The relatively long time from the first apoplectic event to a recurrence suggests long-term patient follow-up is necessary.

Autophagy and Pituitary Adenoma

Pituitary adenomas (PAs) are common, benign intracranial tumors that are usually effectively controlled with surgery, pharmacotherapy or radiotherapy. Some PAs against which conventional treatment is ineffective are great clinical challenges at present. Autophagy is a widespread physiological process in cells. Through autophagy, cells can degrade damaged or redundant proteins and organelles and achieve the recycling of intracellular substances to maintain the homeostasis of the intracellular environment. An increasing number of studies have demonstrated the importance of autophagy in tumor therapy. Both radiotherapy and chemotherapy can induce autophagy, which plays different roles in the course of therapy. In recent years, there has been growing interest in the role of autophagy during the treatment of PAs. This chapter reviews the recent progress of research on autophagy in PA and the autophagic mechanisms in the treatment of PA.

Sphenoid Sinus Fat Packing in Transsphenoidal Surgery: Long-Term Fate Assessment Using Magnetic Resonance Imaging

Background and Objectives: Following the transsphenoidal approach (TSA), appropriate sphenoid sinus fat packing has been preferred to prevent postoperative cerebrospinal fluid leakage; however, studies on the behavior of fat tissue transplanted in the sphenoid sinus are lacking. This study aimed to determine the long-term fate of these fat grafts using magnetic resonance imaging (MRI).Subjects and Method: A total of 139 postoperative MRI scans of 41 patients who underwent sphenoid sinus fat packing using the standard TSA were evaluated. Additionally, MRI time series indicating the vital fat volumes were assessed postoperatively.Results: In 82.9% of cases, the fat volumes measured in the final MRI scans declined to <20% of the initial volumes; only 4.9% of cases exhibited declines to >60% of the initial volume. The fat tissue volume decreased significantly with time, with a median half-life of 18 months. Typically, the sphenoid sinus was eventually almost filled with air rather than transplanted fat. In the subgroup analysis, the fat clearance rate was significantly lower in patients with residual tumors than in those without such remnants (p=0.013).Conclusion: Long-term MRI surveillance of fat grafts in the sphenoid sinus revealed that the transplanted fat graft had degraded and was gradually eliminated.

Rate of rhinosinusitis and sinus surgery following a minimally destructive approach to endoscopic transsphenoidal hypophysectomy

BACKGROUND

There remains considerable variation in the extent of sinonasal preservation during the approach for endoscopic transsphenoidal hypophysectomy (TSH). We advocate for a minimally destructive approach utilizing turbinate lateralization, small posterior septectomy, no ethmoidectomy, and preservation of nasoseptal flap (NSF) pedicles bilaterally. Due to these factors, this approach may affect the rates of postoperative rhinosinusitis. The objective of this study is to define the rates of postoperative rhinosinusitis in patients undergoing this approach.

METHODS

Single institution, retrospective chart review of patients undergoing TSH from 2005 to 2018.

RESULTS

A total of 415 patients were identified and 14% developed an episode of postoperative rhinosinusitis within 3 months. These patients were significantly more likely to have had a history of recurrent acute or chronic rhinosinusitis. Most cases were sphenoethmoidal sinusitis managed with 1 to 2 courses of antibiotics. Of patients with postoperative rhinosinusitis, most did not undergo NSF. Average follow-up was 38 months. Six patients (1.4%) underwent post-TSH functional endoscopic sinus surgery (FESS). Average time from TSH to FESS was 26.3 months. Two of these patients had a history of prior chronic rhinosinusitis without polyposis. Two patients underwent revision TSH for recurrent tumor as the primary indication for surgery at time of FESS. Twenty-two-item Sino-Nasal Outcome Test (SNOT-22) scores generally increased immediately postoperatively, but frequently decreased below preoperative level by the time of last follow-up, regardless of whether patients developed rhinosinusitis.

CONCLUSION

Sinonasal preservation during TSH is associated with a low rate of postoperative rhinosinusitis requiring FESS and excellent long-term patient reported outcomes. We continue to advocate for sinonasal preservation during pituitary surgery.

Anatomical Workspace Study of Endonasal Endoscopic Transsphenoidal Approach

Purpose

To determine the workspace through an anatomical dimensional study of the skull base to further facilitate the design of the robot for endonasal endoscopic transsphenoidal (EET) surgery.

Methods

There were 120 cases having a paranasal sinus CT scan in the database. The internal volumes of the nasal cavities (NC), the volumes of the sphenoid sinuses (SS), and the distance between the anterior nasal spine and base of the sellar (d-ANS-BS) were measured.

Results

The Pearson correlation coefficient (PCC) between the relevant distances and the volumes of the right NC was 0.32; between the relevant distances and the volumes of the left NC was 0.43; and between the relevant distances and volumes of NC was 0.41; with a statistically significant difference (p < 0.001). All PCCs had a statistically significant meaningful difference (p < 0.05).

Conclusion

The volume of NCs were significantly correlated with distances (p < 0.05). The safest and shortest distance to guide the robotic arm length in the EET approach could be represented by d-ANS-BS. This result was also used as primary information for further robotic design.

Management of Nonfunctioning Recurrent Pituitary Adenomas

Pituitary adenomas are typically slow-growing benign tumors. However, 50% to 60% of tumors progress following subtotal resection and up to 30% recur after apparent complete resection. Options for treatment of recurrent pituitary adenomas include repeat surgical resection, radiation therapy, and systemic therapies. There is no consensus approach for the management of recurrent pituitary adenomas. This article reviews the natural history of recurrent adenomas and emerging biomarkers predictive of clinical behavior as well as the outcomes associated with the various treatment modalities for these challenging tumors, with an emphasis on the surgical treatment.

Endocrinological Outcome of Endoscopic Transsphenoidal Surgery for Functioning and Non-Functioning Pituitary Adenoma

Introduction

The present study analysed the (i) remission and preservation of hormones, (ii) endocrinological and anatomical complications and (iii) visual improvement after endoscopic transsphenoidal surgery (ETS).

Methods

The retrospective observational study of all consecutive cases of pituitary adenoma treated with ETS in Hospital Kuala Lumpur (HKL) between 2006 and 2015. Age, sex, pre- and post-operative hormone level, tumour size, and complications were noted.

Results

A total of 67 patients were diagnosed with non-functioning pituitary adenoma throughout this period. Of these, 11 patients had both visual and hormonal improvement post-operation. Of the 27 patients with tumour invaded into the cavernous sinus, 13 showed an improved vision. In the adenoma patients who had impaired hormonal function before the surgery, the hormone level normalised post-surgery in 42 patients. Moreover, 39 patients were diagnosed with functioning pituitary adenoma. Ten patients recovered from acromegaly and four patients recovered from Cushing disease within seven days post-operative. Also, five patients with functioning adenoma suffered complications.

Conclusion

Outcome for the preservation and hormone recovery in non-functioning pituitary adenoma group was satisfactory, with only one patient’s hormonal level worsening. No visual deterioration and mortality were detected throughout this study. A dedicated team specialised in endoscopic transsphenoidal pituitary surgery further improved the outcome of this surgical method.

A cadaveric model for measuring sinonasal continuous positive airway pressure-a proof-of-concept study

BACKGROUND

Obstructive sleep apnea is a common respiratory disorder that can have negative effects on health and quality of life. Positive pressure therapy (CPAP) is the primary treatment. There is a lack of consensus on the risk of postoperative CPAP after endoscopic sinus or skull base surgery. We present a proof-of-concept cadaver model for measuring sinonasal pressure delivered by CPAP.

METHODS

Three fresh cadaver heads were prepared by removing the calvaria and brain. Sphenoidotomies were made and sellar bone was removed. Pressure sensors were placed in the midnasal cavity, sphenoid sinus, and sella. CPAP was applied and the delivered pressure was recorded at increasing levels of positive pressure. Paired t tests and intraclass correlation coefficients were used to analyze results.

RESULTS

Increases in positive pressure led to increased pressure recordings for all locations. Nasal cavity pressure was, on average, 81% of delivered CPAP. Pressure was highest in the sphenoid sinus. The effect of middle turbinate medialization on intrasphenoid pressure was not statistically significant in 2 heads. Intrasellar pressure was 80% of delivered CPAP with lateralized turbinates and 84% with medialized turbinates. Pressure recordings demonstrated excellent reliability for all locations. All heads developed non-sellar-based cranial base leaks at higher pressures. Cribriform region leaks were successfully sealed with DuraSeal®.

CONCLUSION

Our proof-of-concept cadaver model represents a novel approach to measure pressures delivered to the nasal cavity and anterior skull base by CPAP. With further study, it may have broader clinical application to guide the safe postoperative use of CPAP in this population.

Technical notes on the endoscopic endonasal approach to the craniovertebral junction for odontoidectomy

INTRODUCTION

Odontoidectomy can help decompress ventral compression of the brainstem and upper cervical spinal cord in the presence of bony abnormalities of the craniovertebral junction (CVJ), e.g., an odontoid pannus. Endonasal approaches have been shown to be associated with lower morbidity compared with traditional transoral approaches. We demonstrated an entirely endonasal approach to the CVJ.

MATERIALS AND METHODS

We presented our technique for performing an endoscopic endonasal odontoidectomy.

RESULTS

The patient underwent an open posterior cervical spinal fusion to stabilize the CVJ due to destabilization that occurs with odontoidectomy either as part of a single procedure or in a staged manner, depending on the surgeon's preference. By using a two-surgeon, multihanded technique in collaboration with neurosurgery, the anterior CVJ was safely approached endoscopically through the nasopharynx. A midline incision was created and the soft tissue was lateralized widely. The first cervical vertebra (C1) arch was removed with a drill exposing the odontoid process and any associated pannus, which were then resected. Because this approach was entirely extradural, no reconstruction was necessary. Closure was accomplished by placing absorbable packing material in the defect and medializing the nasopharyngeal tissues.

CONCLUSION

Endoscopic endonasal odontoidectomy offers excellent exposure and less morbidity than traditional transoral approaches. This technique should be considered in appropriately selected patients.