Intraoperative Ultrasound-Assisted Endoscopic Endonasal Resection of a Rathke’s Cleft Cyst in an Atypical Location: Using a Novel Small Ultrasound Probe

Introduction: The surgical resection of skull base lesions through the endoscopic endonasal approach (EEA) poses challenges due to anatomical complexity and limited visualization. While intraoperative ultrasound (IUS) is gaining popularity as an adjunct to EEA, its widespread adoption is hindered by the large probe size and suboptimal imaging quality. Routine use of forward-looking phased array probes provides a limited visualization of parasellar regions, given bone artifacts and near-field visualization. Small-probe IUS shows promise in addressing these limitations, providing accurate real-time imaging feedback during EEA to complex lesions. In this study, the authors present the surgical application of a novel small-probe IUS in a case of recurrent Rathke’s cleft cyst (RCC) located in an atypical retrosellar region, causing extensive dorsum sella and upper clival erosion.

Objective: This study highlights the role of small-probe IUS as an adjunct in enhancing visualization, offering real-time guidance, and optimizing resection techniques for complex skull base lesions during EEA.

Methods: A novel small-probe minimally invasive ultrasound with a tip size of 6 mm and shaft length of 150 mm was integrated into the extended transclival EEA in a patient with a retrosellar RCC. The system involved a high-resolution B-mode Doppler-powered transducer. After initial routine nasal and sphenoidal phases, complete removal of the sellar floor, dorsum sellae, posterior clinoid processes, and upper clivus was performed to completely expose the sellar and prepeduncular dura. IUS findings were documented pre- and post-cyst removal.

Results: The new small-probe IUS successfully aided in delineating the margins of the cyst, posterior to the posterior pituitary gland, and identifying the cavernous and paraclival segments of bilateral internal carotid arteries alongside standard endoscopic instruments. Following initial decompression of the cyst, the ultrasound probe was inserted into the resection cavity to ensure the lack of residual wall or aberrant extension to the cavernous sinus and the interpeduncular fossa, as well as to confirm the restoration of the pituitary gland and prepeduncular dura’s configuration. No adverse events or interference with surgical maneuverability was observed. The IUS findings regarding the relationship of the cyst to the nearby normal gland and interpeduncular cistern were congruent to the preoperative MRI. Following the initial decompression of the cyst, an extensive marsupialization was performed, followed by cyst wall resection using circumferential extracapsular dissection. The blind corners of the field, including the anteromedial compartment of the cavernous sinuses and lateral compartments of the interpeduncular fossa, were checked to ensure gross total removal without the need for a dural opening over these areas. Postoperative imaging confirmed cyst removal and restoration of the pituitary gland ([Figs. 1] and [2]).

Conclusion: IUS is a cheap two-dimensional navigation tool with evolving uses during transsphenoidal surgery. It facilitates accurate localization of the lesion and critical surrounding neurovascular structures. The novel small-probe IUS is a promising surgical adjunct, providing good quality real-time navigation while allowing free surgical maneuverability. It potentially decreases operation times and visualizes tumor remnants, thereby increasing the extent of resection. Ongoing technological advancements in neuroradiology are still expected to enhance the role of IUS in endoscopic endonasal procedures.

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Artikel online veröffentlicht:
05. Februar 2024