Optic nerve mobilization to enhance the exposure of the pituitary stalk during craniopharyngioma resection: early experience

Cranio-Orbital Approach and Decompression of the Optic Nerves: A 2-Stage, 4-by-4-Step Approach to Improve Vision in Sellar and Parasellar Lesions

BACKGROUND AND OBJECTIVES

Despite advances in cranial base techniques, surgery of the sellar and parasellar regions remains challenging because of complex neurovascular relationships. Lesions within this region frequently present with progressive visual deterioration caused by distortion and compression of the optic chiasm and nerves. In addition to the direct mass effect from mechanical forces acting on the optic apparatus, these lesions alter blood supply and reduce vascular perfusion, prompting surgical treatment to remove the lesion, alleviate compression, and improve blood flow to the optic nerve. We sought to describe a 2-stage, 4-by-4-step approach, broken down and described as a "four-by-four" technique for optic apparatus decompression and a wide approach to different sellar and parasellar lesions.

METHODS

We describe the operative nuances and key anatomic points in the microsurgical removal of sellar and parasellar lesions. The technique is illustrated with examples of different cases with pre- and follow-up MRI imaging and a brief overview of visual outcomes.

RESULTS

The described technique has been demonstrated in various lesions in 5 patients. Patients presented with bilateral visual loss in 4 (80.0%) cases and with unilateral visual loss in 1 (20.0%) case. Improvement in visual function was noted in all cases, confirmed with visual acuity and visual field testing.

DISCUSSION

The transcranial approach ("from above") remains an important surgical option for patients with excellent exposure and visualization of the sellar and parasellar regions. It permits early access to the optic canal for careful microsurgical decompression and relaxation of the optic nerve to preserve and improve its microvascularization and ultimately vision.

CONCLUSION

The authors augmented the 2-stage, 4-by-4-step technique of decompression with elaborate illustrations of diverse sellar and parasellar lesions to demonstrate the versatility of this approach.

Cisternal, Falciform, and Optic Canal Decompression Influencing Optic Nerve Biomechanics: A Microsurgical Anatomic Study

BACKGROUND

Questions remain regarding optic nerve (ON) physiology, mechanical compliance, and microvasculature, particularly surgical outcomes and atypical visual field defects associated with sellar/parasellar pathology (eg, tumors and aneurysms).

OBJECTIVE

To study the microsurgical/histological anatomy of each ON segment and corresponding microvasculature, calculate area of optic-carotid space at each decompression stage, and measure ON tension before/after compression.

METHODS

Five cadaveric heads (10 sides) underwent sequential dissection: (1) intradural (arachnoidal) ON dissection; (2) falciform ligament opening; (3) anterior clinoidectomy, optic canal decompression, and ON sheath release. At each step, we pulled the nerve superiorly/laterally with a force meter and measured maximal mobility/mechanical tension in each position.

RESULTS

Cisternal ON microvasculature was more superficial and less dense vs the orbital segment. ON tension was significantly lower with higher mobility when manipulated superiorly vs lateromedially. Optic-carotid space significantly increased in size at each decompression stage and with ON mobilization both superiorly and laterally, but the increase was statistically significant in favor of upward mobilization. At decompression step, upward pull provided more space with less tension vs side pull. For upward pull, each step of decompression provided added space as did side pull.

CONCLUSION

Opening the optic canal, falciform ligament, and arachnoid membrane decompresses the ON for safer manipulation and provided a wider optic-carotid surgical corridor to access sellar/parasellar pathology. When tailoring decompression, the ON should be manipulated superiorly rather than lateromedially, which may guide surgical technique, help prevent intraoperative visual deterioration, facilitate postoperative visual improvement, and help understand preoperative visual field deficits based on mechanical factors.

Expanded Transsphenoidal Trans-Lamina Terminalis Approach to Tumors Extending Into the Third Ventricle: Technique Notes and a Single Institute Experience

Object

The trans lamina terminalis approach (TLTA) has been described as a way to remove third ventricular tumors. The aim of this paper was to analyze the feasible outcomes of TLTA applied to tumors extending into the third ventricle in our institute.

Methods

Suprasellar tumors (n = 149) were treated by the extended endonasal approach from September 2019 to December 2020 in Beijing Tiantan Hospital. Eleven of the tumors were treated by TLTA or TLTA via the trans-chiasm-pituitary corridor (TCPC). The surgical technique notes of TLTA were described and indications and outcomes of the approach were analyzed.

Results

There were 11 patients enrolled in the study, six with papillary craniopharyngiomas, two with adamantinomatous craniopharyngiomas, one with a germinal cell tumor (GCT), one with cavernous malformation and one with chordoid glioma. Four of the patients received a radical resection by TLTA alone, while seven of them received TLTA via the TCPC. Gross total resection was achieved in eight patients (72.7%), and partial resection in three patients (27.3%). Visual function was improved in four of the 11 patients (36.4%), was unchanged in five patients (45.5%), and deteriorated in two patients (18.2%). New-onset hypopituitarism occurred in seven patients (63.3%) and new-onset diabetes insipidus occurred in two patients (18.2%). Electrocyte imbalance were observed in six patients (54.5%) at post-operative week 2. There were no surgery-related deaths or cerebrospinal fluid leaks. Postoperative intracranial infection was observed in one patient (9.1%), and during the follow-up period, tumor recurrence occurred in one patient (9.1%).

Conclusion

The expanded TLTA provides a feasible suprachiasm corridor to remove tumors extending into the third ventricle, especially for craniopharyngiomas. Sound understanding of the major strengths and limitations of this approach, as well as strategies for complication avoidance, is necessary for its safe and effective application.

Interoptic, Trans-lamina Terminalis, Opticocarotid Triangle, and Caroticosylvian Windows From Mini-Supraorbital, Frontomedial, and Pterional Perspectives: A Comparative Cadaver Study With Artificial Lesions

Introduction: The mini-supraorbital (MSO) and pterional (PT) approaches have been compared in a number of studies focusing on the treatment of aneurysms, craniopharyngiomas, and meningiomas. The goal of this study was to analyze the surgical exposure to different artificial lesions through interoptic (IO), trans-lamina terminalis (TLT), opticocarotid triangle (OCT), and caroticosylvian (CS) windows from the MSO, frontomedial (FM), and PT perspectives. Methods: The MSO, PT, and FM approaches were performed sequentially in two fixed cadaver heads. Three colored spheres were placed around the optic chiasm: (1) between the optic nerves; (2) between the optic nerve and the internal carotid artery; and (3) between the internal carotid artery and the oculomotor nerve. The surgical exposures to these structures by using the IO, TLT, OCT, and CS windows were compared. Results: (1) IO window: from the MSO and PT approaches, the total surgical exposure mainly allows visualization of contralateral lesions. The FM approach was superior for exploration of both sides of the area between the optic nerves. (2) TLT pathway: the MSO and PT approaches mainly expose the contralateral third ventricle wall. (3) OCT window: the PT approach allows exposure of a larger part of the sphere between the optic nerve and the internal carotid artery than the MSO approach. (4) CS window: the PT approach allows a better exposure of lateral structures such as the oculomotor nerve and of the medial prepontine area in comparison to the MSO approach. Conclusion: Simulation of the surgical situation with artificial lesions is a good model for comparing surgical perspectives and for analyzing feasibility of lesion exposure and resection.

Transcranial Evacuation of Atypical Progressive Supradiaphragmatic Hematoma After Transsphenoidal Complete Resection of Pituitary Adenoma

OBJECTIVE

Supradiaphragmatic hematoma is a type of hematoma that occurs after transsphenoidal (TS) resection of pituitary adenoma and requires special management.

METHODS

Two patients had symptomatic supradiaphragmatic hematomas after total TS resection of pituitary adenomas in the absence of vascular anomalies. Both patients also had hydrocephalus at the time of diagnosis of the hematoma. The initial endoscopic endonasal inspection showed no subdiaphragmatic bleeding. The hematoma was evacuated via a frontolateral approach after insertion of an external ventricular drain (EVD).

RESULTS

The supradiaphragmatic hematoma could be clinically and radiologically distinguished. It presented early with visual deterioration without headache. The patients developed hydrocephalus, which was associated with deterioration of level of consciousness. Radiologically, the hematoma filled the suprasellar space and was associated with the extension of bleeding in the basal cisterns. Recovery was good in both patients. There were no permanent neurologic deficits. The EVD was removed in both patients. One patient required a ventriculoperitoneal shunt because of delayed hydrocephalus.

CONCLUSIONS

Supradiaphragmatic hematoma can be clinically and radiologically distinguished from other types of hematoma occurring after TS resection of pituitary adenoma. Transcranial surgery should be performed to manage supradiaphragmatic hematoma, when symptomatic. Insertion of an EVD at the time of evacuation is mandatory to relax the brain and to alleviate the hydrocephalus.

Frontolateral Approach Applied to Sellar Region Lesions: A Retrospective Study in 79 Patients

Background:

Various surgical approaches for the removal of sellar region lesions have previously been described. This study aimed to evaluate the reliability and safety of the frontolateral approach (FLA) to remove sellar region lesions.

Methods:

We presented a retrospective study of 79 patients with sellar region lesions who were admitted and operated by the FLA approach from August 2011 to August 2015 in Department of Neurosurgery of Beijing Tian Tan Hospital. We classified FLA into three types, compared the FLA types to the areas of lesion invasion, and analyzed operation bleeding volume, gross total resection (GTR) rate, visual outcome, and mortality.

Results:

Seventy-nine patients were followed up from 2.9 to 50.3 months with a mean follow-up of 20.5 months. There were 42 cases of meningiomas, 25 cases of craniopharyngiomas, and 12 cases of pituitary adenomas. The mean follow-up Karnofsky Performance Scale was 90.4. GTR was achieved in 75 patients (94.9%). Two patients (2.5%) had tumor recurrence. No patients died perioperatively or during short-term follow-up. Three patients (3.8%) with craniopharyngioma died 10, 12, and 23 months, respectively, after surgery. The operative bleeding volume of this study was no more than that of the other approaches in the sellar region (P = 0.783). In this study, 35 patients (44.3%) had visual improvement after surgery, 38 patients (48.1%) remained unchanged, and three patients’ visual outcome (3.8%) worsened.

Conclusions:

FLA was an effective approach in the treatment of sellar region lesions with good preservation of visual function. FLA classification enabled tailored craniotomies for each patient according to the anatomic site of tumor invasion. This study found that FLA had similar outcomes to other surgical approaches of sellar region lesions.