Tricks and traps of ICG endoscopy for effectively applying endoscopic transsphenoidal surgery to pituitary adenoma

Endoscopic Endonasal Transsphenoidal Surgery for Intrasellar Mixed Germ Cell Tumors

A mixed germ cell tumor (MGCT) in the neurohypophysis is very rare, with only a few reported cases1-4 but none with surgical videos. In this report, the endoscopic endonasal transsphenoidal approach for MGCT in the neurohypophysis is presented (Video 1). A 12-year-old girl with ocular pain, fatigue, and nausea presented with gradual onset of quadrant hemianopsia and left oculomotor palsy. Magnetic resonance imaging showed an enhanced mass in the sella turcica with multiple components involving the pituitary gland and stalk. Her endocrinological examination showed decreased levels of pituitary hormones and simultaneously elevated serum levels of alpha-fetoprotein and beta-human chorionic gonadotropin. After pituitary hormone replacement, endoscopic endonasal transsphenoidal surgery was planned. The tumor was strongly adherent to the surrounding structures, and gross total resection was achieved. The histological diagnosis was MGCT with a teratoma component. Postoperatively, her vision and oculomotor palsy improved swiftly, and adjuvant chemotherapy and radiotherapy were administered. In this case, 3-dimensional computer graphics were created from the preoperative computed tomography and magnetic resonance imaging studies. Preoperative simulation with the 3-dimensional computer graphic images and intraoperative verification with indocyanine green images facilitated our understanding of the surrounding anatomy, including the tumor components, pituitary gland, and internal carotid arteries.5 After removal of the tumor, multilayer fascial closure was performed for skull base reconstruction.6 MGCT in the neurohypophysis can be strongly adherent to the surrounding structures, requiring careful dissection and resection under endoscopy. At the last follow-up (8 months after surgery), the tumor was successfully controlled, and the patient had no neurological symptoms with pituitary hormone replacement therapy.

Indocyanine green endoscopic evaluation of pituitary stalk and gland blood flow in craniopharyngiomas

To assess the use of indocyanine green (ICG) fluorescence endoscopy to evaluate pituitary blood flow in craniopharyngioma resection and its possible impact on intraoperative decisions regarding pituitary stalk processing. Patients with craniopharyngiomas who had undergone transsphenoidal surgery since March 2021, when an ICG endoscope was introduced at the Kagoshima University Hospital, were included in the study. When targeted tumor removal was approaching completion, 10 mg of ICG was administered intravenously to evaluate blood flow in the pituitary stalk and gland. ICG signals and endocrinological status before and after surgery were evaluated retrospectively. Pituitary stalk and gland blood flow were evaluated as positive (++), weakly positive (+), and no signal (-).Ten patients with craniopharyngiomas underwent transsphenoidal surgery using an ICG endoscope (mean age 56.6 ± 14.2 years; 40% male). Among the eight patients in whom the pituitary stalk was preserved, pituitary function with positive signal on the stalk was intact in two. Two other patients with weakly positive stalk and positive pituitary gland signals showed intact function or minimal pituitary dysfunction. Four patients had impairments in more than three axes with poor ICG signals in the stalk or pituitary gland. Two patients underwent pituitary amputation because of high tumor invasion and lack of ICG signal in the stalk after tumor removal, resulting in panhypopituitarism. A negative ICG signal in the pituitary stalk is likely to indicate postoperative pituitary function loss. Craniopharyngioma surgery using ICG endoscopy may be useful for predicting endocrine prognosis and improving tumor outcomes.

Indocyanine Green Endoscopy for Pituitary Adenomas with Parasellar Extension: Results from a Preliminary Case Series

BACKGROUND

Advances in visualization tools have brought new confidence, including endoscope-integrated indocyanine (E-ICG), which makes pituitary and skull-base surgery safer and more effective. We report here our preliminary experience with the use of E-ICG to 1) visualize the cavernous segment of the internal carotid artery (ICA); and 2) functionally and anatomically preserve the pituitary gland.

METHODS

A dedicated ICG-integrated endoscope was used in 15 patients with parasellar pituitary adenomas. Indocyanine was administered at 2 different time points during surgery: an early bolus of 12.5 mg at the sphenoid sinus opening to expose the position of the parasellar segment of the ICAs and to identify the position of the normal pituitary gland so that it could be preserved during tumor removal. Subsequently, a second late bolus of 12 mg of ICG was injected to obtain a real-time "wire angiographic" visualization of the flow of the ICAs.

RESULTS

Gross total resection was achieved in 12 cases (80%), whereas subtotal resection was performed in the other 3 cases (20%). The pituitary gland was clearly discernable in 11 cases (91.6%). None of the patients manifested new endocrinologic deficits or major vascular complications.

CONCLUSIONS

E-ICG is a safe and essential aid for pituitary adenomas invading the cavernous sinus. Its performance as a pituitary marker and real-time video angiography showed promising results in terms of extent of resection, endocrinologic outcomes, and prevention of intraoperative complications.

Fluorescence-Guided Surgery: A Review on Timing and Use in Brain Tumor Surgery

Fluorescence-guided surgery (FGS) allows surgeons to have improved visualization of tumor tissue in the operating room, enabling maximal safe resection of malignant brain tumors. Over the past two decades, multiple fluorescent agents have been studied for FGS, including 5-aminolevulinic acid (5-ALA), fluorescein sodium, and indocyanine green (ICG). Both non-targeted and targeted fluorescent agents are currently being used in clinical practice, as well as under investigation, for glioma visualization and resection. While the efficacy of intraoperative fluorescence in studied fluorophores has been well established in the literature, the effect of timing on fluorophore administration in glioma surgery has not been as well depicted. In the past year, recent studies of 5-ALA use have shown that intraoperative fluorescence may persist beyond the previously studied window used in prior multicenter trials. Additionally, the use of fluorophores for different brain tumor types is discussed in detail, including a discussion of choosing the right fluorophore based on tumor etiology. In the following review, the authors will describe the temporal nature of the various fluorophores used in glioma surgery, what remains uncertain in FGS, and provide a guide for using fluorescence as a surgical adjunct in brain tumor surgery.

Fluorophores Use in Pituitary Surgery: A Pharmacokinetics and Pharmacodynamics Appraisal

(1) Background: Despite many surgical and technological advances, pituitary adenoma surgery is still burdened by non-negligible rates of incomplete tumor resection, mainly due to difficulties in differentiating pathology from normal pituitary tissue. Some fluorescent agents have been recently investigated as intraoperative contrast agents in pituitary surgery. The aim of this study is to evaluate the actual knowledge about the usefulness of such fluorophores with a particular focus on both the pharmacokinetics and pharmacodynamics issues of the pituitary gland. (2) Methods: We reviewed the current literature about fluorophores use in pituitary surgery and reported the first fully endoscopic experience with fluorescein. (3) Results: The studies investigating 5-ALA use reported contrasting results. ICG showed encouraging results, although with some specificity issues in identifying pathological tissue. Low-dose fluorescein showed promising results in differentiating pathology from normal pituitary tissue. Apart from the dose and timing of administration, both the fluorophores' volume of distribution and the histological variability of the interstitial space and vascular density played a crucial role in optimizing intraoperative contrast enhancement. (4) Conclusions: Both pharmacokinetics and pharmacodynamics issues determine the potential usefulness of fluorophores in pituitary surgery. ICG and fluorescein showed the most promising results, although further studies are needed.