Surgical outcomes of the minimum anterior and posterior combined transpetrosal approach for resection of retrochiasmatic craniopharyngiomas with complicated conditions

Characteristics and Outcomes in Pediatric Versus Adult Craniopharyngiomas: A Systematic Review and Meta-Analysis

BACKGROUND

Craniopharyngiomas account for 1.2% to 4.6% of all intracranial tumors. Although age at presentation is distributed bimodally, with a pediatric peak occurring between 5 and 15 years and an adult peak between 50 and 70 years, presentation, treatment, and outcome differences between these two craniopharyngioma populations have not been thoroughly characterized.

OBJECTIVE

To compare treatments and outcomes between adult and pediatric craniopharyngiomas.

METHODS

This is a systematic review and meta-analysis. Web of Science, MEDLINE, and Scopus databases were searched for primary studies reporting postoperative complications, functional outcomes, recurrence, and overall survival in patients with craniopharyngioma undergoing surgery.

RESULTS

The search yielded 1,202 unique articles, of which 106 (n=4,202 patients) met criteria for qualitative synthesis and 23 (n=735 patients) met criteria for meta-analysis. Compared with adult, pediatric craniopharyngiomas were less likely to present with visual defects (odds ratio [OR] 0.54, 95% CI 0.36-0.80) or cognitive impairment (OR 0.29, 95% CI 0.12-0.71) and more likely with headaches (OR 2.08, 95% CI 1.16-3.73). Children presented with significantly larger tumors compared with adults (standardized mean difference 0.68, 95% CI 0.38-0.97). Comparing functional outcomes, pediatric patients sustained higher rates of permanent diabetes insipidus (OR 1.70, 95% CI 1.13-2.56), obesity (OR 3.15, 95% CI 1.19-8.31), and cranial nerve and/or neurological defects (OR 4.87, 95% CI 1.78-13.31) than adults. No significant differences were found in rates of postoperative cerebrospinal fluid leak, overall or progression-free survival, or recurrence.

CONCLUSION

Adult and pediatric craniopharyngiomas seem to have fundamental differences in clinical presentation and functional outcomes. These patients frequently require multimodality treatment and are best managed with a multidisciplinary team and an individualized approach.

Gross-total resection of a suprasellar with recurrent cerebellopontine angle region craniopharyngioma by endoscopic far-lateral supracerebellar infratentorial approach: illustrative case

BACKGROUND

Craniopharyngiomas that rarely extend into the posterior fossa are treated with staged operations or combined approaches. The authors reported a patient undergoing gross-total resection of a suprasellar with recurrent cerebellopontine angle (CPA) craniopharyngioma using an endoscopic far-lateral supracerebellar infratentorial approach (EFL-SCITA).

OBSERVATIONS

The patient was a 15-year-old boy who presented with headache and decreased vision that lasted for half a year. He previously received three surgeries related to CPA craniopharyngioma. Preoperative magnetic resonance imaging revealed a suprasellar with recurrent CPA craniopharyngioma. Gross-total resection of this suprasellar and CPA tumor was achieved through EFL-SCITA. All symptoms and signs were improved. There were no postsurgical complications except for mild facial paralysis.

LESSONS

EFL-SCITA can be used not only for tumors in the posterolateral pontomesencephalon and ptero-clival-tentorial area but also for tumors in the suprasellar region with posterior fossa extension.

The mini-combined transpetrosal approach: an anatomical study and comparison with the combined transpetrosal approach

BACKGROUND

The combined transpetrosal approach (CTPA) is a versatile technique suitable for challenging skull base pathologies. Despite the advantages provided by a wide surgical exposure, the soft tissue trauma, complex and time-consuming bony work, and cosmetic issues make it far from patient expectations. In this study, the authors describe a less invasive modification of the CTPA, the mini-combined transpetrosal approach (mini-CTPA), and perform a quantitative comparison between these two approaches.

METHODS

Five human specimens were used for this study. CTPA was performed on one side and mini-CTPA on the opposite side. The surgical freedom, petroclival and brainstem area of exposure, and maneuverability for 6 anatomical targets, provided by the CTPA and mini-CTPA, were calculated and statistically compared. The bony volumes corresponding to each anterior petrosectomy were also measured and compared. Three clinical cases with an operative video are also reported to illustrate the effectiveness of the approach.

RESULTS

The question-mark skin incision done along the muscle attachments permits an optimal cosmetic result. Even though the limited incision, the smaller craniotomy, and the less extensive bone drilling of mini-CTPA provide a smaller area of surgical freedom, the areas of exposure of petroclival region and brainstem were not statistically different between the two approaches. The antero-posterior maneuverability for the oculomotor foramen (OF), Meckel's cave (MC) and the REZ of trigeminal nerve, and the supero-inferior maneuverability for OF, MC, Dorello's canal, and REZ of CN VII are significantly reduced by the smaller opening. The bony volume of anterior petrosectomy resulted similar among the approaches.

CONCLUSIONS

The mini-CTPA is an interesting alternative to the CTPA, providing comparable surgical exposure both for petroclival region and for brainstem. Although the lesser soft tissue dissection and bony opening decrease the surgical maneuverability, the mini-CTPA may reduce surgical time, potential approach-related morbidities, and improve cosmetic and functional outcomes for the patients.

Modified Transpetrosal-Transtentorial Approach for Resection of Large and Giant Petroclival Meningioma: Technical Nuance and Surgical Experiences

BACKGROUND

 Meningiomas arising from the petroclival area remain a challenge for neurosurgeons. Various approaches have been proposed to achieve maximum resection with minimal morbidity and mortality. Also, some articles correlated preservation of adjacent veins with less neurologic deficits.

OBJECTIVE

 To describe the experiences in using a new technique to achieve maximal resection of petroclival meningiomas and preserving the superior petrosal veins (SPVs) and the superior petrosal sinus (SPS).

METHODS

 A retrospective analysis of 26 patients harboring a true petroclival meningioma with a diameter ≥25 mm and undergoing surgery with the modified transpetrosal-transtentorial approach (MTTA) was performed.

RESULTS

 Fifty-four percent of 22 patients complained of severe headache at presentation. There was also complaint of cranial nerve (CN) deficit, with CN VII deficit being the most common (present in 42% of patients). The average tumor size (measured as maximum diameter) was 45.2 mm, and most of the tumors compressed the brainstem. Total resection was achieved in 12 patients (46.2%), whereas the others were excised subtotally (54.8%). Most of the patients had WHO grade I (96.1%) meningioma; only one had a grade II (3.8%) meningioma. In addition, clinical improvement and persistence of symptoms were observed in 17 (65.4%) and 8 (30.7%) patients, respectively, and postoperative permanent CN injury was observed in 3 (11.5%) patients.

CONCLUSION

 Using the MTTA, maximal resection with preservation of the CNs and neurovascular SPV-SPS complex can be achieved. Therefore, further studies and improvements of the technique are required to increase the total resection rate without neglecting the complications that may develop postoperatively.

Tentorial Peeling: Surgical Extradural Navigation to Protect the Temporal Lobe in the Focused Combined Transpetrosal Approach

BACKGROUND

Transpetrosal approaches have been used for treatment of tumors in the petroclival region for many years. Injury to the temporal lobe, however, has been a potential drawback of the techniques described to date.

OBJECTIVE

To describe modifications of the transpetrosal surgical technique, which allows extradural manipulation of the temporal lobe during the focused combined transpetrosal approach. This extra layer of protection avoids mechanical brain retraction, direct trauma to the temporal lobe and disruption of the local venous structures.

METHODS

The present manuscript describes an innovative technical nuance based on the combination of the focused combined transpetrosal approach, the peeling of the dural layers of the tentorium, and the reverse peeling of the middle fossa dura mater. Ample illustrative material is provided and illustrative cases are presented.

CONCLUSION

Peeling of the dural layers of the tentorium is a promising modification of the transpetrosal approach to increase the safety of the temporal lobe manipulation.

Variability in Wall Thickness and Related Structures of Major Dural Sinuses in Posterior Cranial Fossa: A Microscopic Anatomical Study and Clinical Implications

BACKGROUND

Regional variability in dural sinus (DS) wall thickness in posterior cranial fossa (PCF) have not been studied in detail yet.

OBJECTIVE

To clarify the possible regional variability in DS wall thickness and determine the occurrence and localization of the chordae Willisii (CW) in PCF.

METHODS

Fifty-nine human cadaveric DSs of PCF were investigated. A measurement of the DS walls/dura mater/CW thickness of parafin-embedded/hematoxylin-eosin stained axial sections was performed by using Cell Sens Science Imaging Software (Olympus Corporation, Tokyo, Japan).

RESULTS

The osseus wall (OW) was the thickest one in the confluens sinuum (CS) and the thinnest one in the jugular bulb (JB) and sigmoid sinus (P < .05). The biggest differences between individual walls were observed in the JB where the superior wall was almost twice as thick as the OW. At the transverse-sigmoid junction, the thickness of the walls was comparable. In the CS and transverse sinuses, the OW was even thicker than the surrounding dura mater. The occurrence and thickness of the CW increased from the JB towards CS and prevailed on the right side. An overall number of the CW in PCF was comparable to that observed in the superior sagittal sinus.

CONCLUSION

The present study displayed for the first time the regional variability in the DS walls thickness and occurrence of the CW in PCF. Application of these findings may afford greater freedom in exposure of the DSs or neoplasms adhering to the DSs.

Approach selection and outcomes of craniopharyngioma resection: a single-institute study

Since there are many approaches for successful craniopharyngioma resection, how to choose a suitable approach remains problematic. The aim of this study was to summarize experience of approach selection and outcomes of craniopharyngioma resection in our institute. The data of 182 primary craniopharyngiomas between January 2013 and June 2019 were retrospectively reviewed. Craniopharyngiomas were classified into intrasellar, intra-suprasellar, suprasellar, and intra-third ventricle types based on the location. The surgical approaches, extent of resection, endocrine and ophthalmological outcomes, and complications were evaluated. Gross total resection (GTR) was achieved in 158 (86.8%) patients, near-total resection (NTR) in 20 (11%), and partial resection (PR) in 4 (2.2%). New-onset hypopituitarism occurred in 90 (49.5%) and new-onset diabetes insipidus in 48 (26.4%). Visual function was improved in 110 of the 182 patients, unchanged in 52, and deteriorated in 20. For intra-suprasellar and suprasellar tumors, patients in the endoscopic endonasal approach (EEA) group had higher GTR rate, lower incidence of new-onset hypopituitarism, and better visual outcome than patients in transcranial approach group, but no significant difference in the incidence of new-onset diabetes insipidus was found. There were no surgery-related deaths, and the common complications included permanent oculomotor nerve palsy, hemorrhage, and cerebrospinal fluid leaks. During the follow-up period, tumor recurrence or regrowth occurred in 6.6% of the cases. Tumor location is key for choosing an optimal surgical approach for craniopharyngioma resection. The EEA should be considered as the first choice for intra-suprasellar and suprasellar craniopharyngiomas to achieve better visual outcomes and fewer pituitary hormonal disorders.

Pediatric craniopharyngioma

BACKGROUND

Craniopharyngioma has historically been recognized to be a formidable pathology primarily due to its proximity to critical neurovascular structures and the challenging surgical corridors that surgeons have tried to reach this lesion.

FOCUS OF REVIEW

In this work, we review the medical and surgical management of these tumors with a focus on clinical presentation, diagnostic identification, surgical approach, and associated adjuvant therapies. We will also discuss our current treatment paradigm using endoscopic, open, and combined approaches to craniopharyngiomas. The management of craniopharyngiomas requires a multidisciplinary team of surgeons, endocrinologists, and neuroanesthesiologists as well as neurocritical care specialists to deliver the most comprehensive and safest surgical resection with minimal postoperative morbidity.

The Transpetrosal-Ridge Approach: A Modification of the Combined Transpetrosal Approach

Background

Petroclival tumors are formidable challenges for skull base surgeons. Obtaining adequate surgical access is a paramount consideration. Although the combined transpetrosal approach provides a wide surgical corridor, it is technically challenging and, to a degree, morbid. This article describes the transpetrosal-ridge approach, which is a modification of the combined transpetrosal approach with improvements with regards to ease of execution and reduced surgical morbidity.

Methods

The key elements of the transpetrosal-ridge approach are outlined, followed by a detailed description of the steps. The head is placed in the lateral position. After skin incision and muscle elevation, a temporo-suboccipital craniotomy is performed. Middle fossa dura is elevated to the petrous ridge. A limited mastoidectomy is performed with preservation of the semicircular canals. The remaining petrous ridge is then resected and the posterior fossa dura is opened, with the opening extending through the trigeminal dural ring.

Results

Steps of the combined transpetrosal approach that do not contribute to the final surgical corridor are omitted. Extensive mastoid and petrous apex resection is avoided. Posterior fossa dural opening extending through the trigeminal dural ring is a critical step, as it detaches the superior petrosal sinus and sigmoid sinus from the petrous bone. With the retraction of the temporal lobe and the cerebellum and sigmoid sinus, a wide surgical corridor is obtained.

Conclusions

The transpetrosal-ridge approach is a modification of the combined transpetrosal approach with optimization of the operative steps while continuing to provide a wide surgical corridor to the petroclival region.

Safe maximal resection of primary cavernous sinus meningiomas via a minimal anterior and posterior combined transpetrosal approach

OBJECTIVE

Meningiomas arising from the cavernous sinus (CS) continue to be a significant technical challenge, and resection continues to carry a relatively higher risk of neurological morbidity in patients with these lesions because of the tumor’s proximity to neurovascular structures. The authors report the surgical outcomes of 9 patients with primary CS meningiomas (CSMs) that were surgically treated using a minimal anterior and posterior combined (MAPC) transpetrosal approach, and they emphasize the usefulness of the approach.

METHODS

This retrospective study included 9 patients who underwent surgery for CSM treatment between 2015 and 2016 via the MAPC transpetrosal approach. Two patients were men and 7 were women, with a mean age of 58.5 years (39–72 years). Five patients (55.5%) had undergone previous treatment. The surgical technique consisted of a temporo-occipito-suboccipital craniotomy and exposure of the posterolateral part of the CS via the presigmoidal MAPC approach. After opening Meckel’s cave and identifying the 3rd–5th cranial nerves in the prepontine cistern, Parkinson’s triangle and supratrochlear triangles were opened. Finally, the tumor occupying the posterolateral part of the CS was removed.

RESULTS

All lesions were safely and maximally removed, with preservation of external ocular movements and preoperative Karnofsky Performance Scale scores. The mean extent of resection was 77.0% (range 58.7%–95.4%). Six patients underwent adjuvant therapy in the form of stereotactic radiosurgery (SRS) or stereotactic radiotherapy (SRT) during the follow-up period; none of these patients experienced recurrence.

CONCLUSION

The authors conclude that the MAPC transpetrosal approach could be superior to other approaches for CSMs, as it provides direct visual access to the posterolateral portion of the CS. In their experience, this approach is an alternative and better option for safe maximal resection of CSMs.

Contralateral Minimum Anterior and Posterior Combined Petrosal Approach for Retrochiasmatic Craniopharyngiomas: An Alternative Technique

Retrochiasmatic craniopharyngiomas (RC) are a challenge for the neurosurgeon to treat surgically, restrained by their location in the interpeduncular fossa, surrounded by vital neurovascular structures, narrow corridor and poor visibility. Many approaches are possible and elucidated in the literature, which the surgeon chooses, based on multiple factors, such as the size of tumor, calcification, laterality, preoperative neurological deficits and the endocrine function status, recurrence, postradiotherapy status, or significant superior and/or posterior extension. 1 2 We describe a contralateral minimum anterior and posterior (CL-MAPC) petrosal approach for a case of recurrent RC, in a 37-year-old female patient operated before using a pterional approach, now presented with left homonymous hemianopia and panhypopituitarism ( Fig. 1 ). We preferred a contralateral approach to protect the ipsilateral optic tract (OT) from retraction injury, which formed an obstacle to the tumor from ipsilateral side. Apart from various benefits described by the author previously for RC, using MAPC petrosal approach, the CL-MAPC offers a safe corridor, protecting the ipsilateral OT, visualization of tumor origin usually posterior to chiasm, wider corridor if PCoM could be sacrificed, as it was done in this case, and pituitary stalk identification, with a probability of its functional preservation, unlike a necessity of pituitary transposition in EEA, though the endocrine outcome is poor after a radical resection irrespective of the approach chosen. 1 3 4 There was complete excision of the tumor with preservation of visual function postoperatively. We recommend the use of CL-MAPC as an alternative to EEA in some specific indications when the tumor is large, calcified, obscuring OT on the ipsilateral side and with significant lateral extension, which may be limiting factors in EEA ( Fig. 2 ). The link to the video can be found at: https://youtu.be/gWCJmh4_evs .

Microscopic versus endoscopic approaches for craniopharyngiomas: choosing the optimal surgical corridor for maximizing extent of resection and complication avoidance using a personalized, tailored approach

Resection remains the mainstay of treatment for craniopharyngiomas with the goal of radical resection, if safely possible, to minimize the rate of recurrence. Endoscopic endonasal and microscopic transcranial surgical approaches have both become standard methods for the treatment for craniopharyngiomas. However, the approach selection paradigm for craniopharyngiomas is still a point of discussion. Choosing the optimal surgical approach can play a significant role in maximizing the extent of resection and surgical outcome while minimizing the risks of potential complications. Craniopharyngiomas can present with a variety of different sizes, locations, and tumor consistencies, and each individual tumor has distinct features that favor one specific approach over another. The authors review standard cranial base techniques applied to craniopharyngioma surgery, using both the endoscopic endonasal approach and traditional open microsurgical approaches, and analyze factors involved in approach selection. They discuss their philosophy of approach selection based on the location and extent of the tumor on preoperative imaging as well as the advantages and limitations of each surgical corridor, and they describe the operative nuances of each technique, using a personalized, tailored approach to the individual patient with illustrative cases and videos.

Aggressive surgery based on an anatomical subclassification of craniopharyngiomas

OBJECTIVE

Craniopharyngiomas remain a particularly formidable challenge in the neurosurgical field. Because these lesions involve the hypothalamus and ophthalmological systems, their resection is associated with either higher rates of mortality and recurrence or a lower rate of radical resection. The authors report the outcomes of aggressive surgeries based on an anatomical subclassification of craniopharyngiomas.

METHODS

Clinical and ophthalmological examinations, imaging studies, endocrinological studies, neuropsychological function, and surgical complications in all patients who had undergone microsurgical resection for craniopharyngioma at Osaka City University hospital between January 2000 and December 2014 were retrospectively reviewed through the medical records. Radical resections were planned in all of the patients. To help choose the correct surgical approach, craniopharyngiomas were classified based on tumor origin. The 4 possible groups included the intrasellar type, prechiasmatic type, retrochiasmatic type, and intra–third ventricle type. A multistage surgery was planned in some cases.

RESULTS

Seventy-two cases of craniopharyngioma were resected. Thirty-two patients (44.4%) had undergone previous surgical procedures at other institutions. Thirty-five cases (48.6%) were classified as retrochiasmatic, 19 (26.4%) as prechiasmatic, 12 (16.7%) as intra–third ventricle, and 6 (8.3%) as intrasellar. In 26 cases (36.1%), multistage surgery was required to complete the radical resection. Overall, 41 cases involved an orbitozygomatic approach; 21, a transpetrosal approach; 21, an interhemispheric approach; and 14, a transsphenoidal approach. In 3 cases, other approaches were applied. Gross-total resection was achieved in 43 patients (59.7%), near-total resection in 28 (38.9%), and partial resection in only 1 patient (1.4%). The mean follow-up period after resection was 4.7 years. Tumor recurrence or regrowth occurred in 15 (20.8%) of the 72 patients, with 14 of the 15 cases successfully controlled after additional resections and stereotactic radiosurgery. However, 1 patient died of uncontrollable tumor progression, and 2 patients died of unrelated diseases during the follow-up. Overall, disease in 69 (95.8%) of 72 patients was well controlled at the last follow-up.

CONCLUSIONS

Aggressive tumor resection is the authors' treatment policy for craniopharyngioma. Using an anatomical subclassification of craniopharyngioma to choose the most appropriate surgical approach is helpful in achieving that goal of aggressive resection.

Factors related to endocrine changes and hormone substitution treatment during pre- and post-operation stages in craniopharyngioma

Factors related to endocrine changes and hormone substitution treatment during pre- and post-operation periods in craniopharyngioma cases were examined. Twenty patients who underwent tumor resection from January 2012 to January 2015 were included in the study. We monitored factors related to endocrine changes and hormone substitution treatment during pre- and post-operation periods. Blood thyroid-stimulating hormone, triiodothyronine, thyroxine, prolactin, follicle-stimulating hormone, luteinizing hormone and cortisol levels were measured in the patients. Urinary volume and urine specific gravity were also measured before and after the operation. After the operation, we observed diabetes insipidus and a decrease in TSH and gonadal hormone levels more frequently compared to pre-operation. However, incidence of high prolactin was markedly reduced following surgery. The number of hypothyroidism cases before and after surgery had no statistical significance. In conclusion, surgery for craniopharyngioma aggravated endocrine dysfunction. Craniotomy and total tumor resection had considerable effects on the endocrine system. Routine hormone therapy as an alternative treatment was necessary after operation. Alternative treatment of adrenal cortex hormones reduced the incidence on low blood cortisol.

Shattering the Rock: Technique of Bilateral Optic Nerve Mobilization and Drilling Heavily Calcified Craniopharyngiomas for Its Excision

BACKGROUND

Resection of heavily calcified craniopharyngioma is quite challenging. The stretched optic nerves, perforators, and stalk are likely to be jeopardized further during attempts to break the calcified chunks, especially through narrow corridors. We describe a surgical technique to mobilize bilateral optic nerves and drill the calcified chunk to crumple it.

METHODS

This technique was used in 6 patients with heavily calcified craniopharyngiomas (2 recurrent) who had presented with progressive visual loss. Frontotemporal craniotomy was used in 5 patients, and fronto-temporo-orbito-zygomatic craniotomy was used in 1 patient with a large retrosellar component. The Sylvian fissure was widely split. The bilateral optic canal was deroofed, and the falciform ligament was cut to mobilize both optic nerves. The calcified tumor could be dissected and mobilized into the widened corridor where the tumor was drilled. Multiple holes were drilled in the calcified chunk to shatter it to small pieces. These pieces were then dissected from perforators and stalk, while protecting them.

RESULTS

Symptoms improved in all of the patients. Gross total excision could be achieved in 3 patients, near total excision in 2 patients (both recurrent), and subtotal excision in 1 patient (because of extensive skull base involvement). All of the patients had transient diabetes insipidus. Two patients who had preoperative hypopituitarism required long-term postoperative hormonal replacement. There were no approach-related complications.

CONCLUSIONS

Mobilizing bilateral optic nerves improves the exposure and allows dissection of arachnoid from calcified craniopharyngiomas. Its drilling through widened corridors helps to shatter it. Using the technique, the neurovascular structures can possibly be better preserved while achieving maximal resection.

Removal of craniopharyngioma via fronto-basal interhemispheric approach

The effectiveness and safety of fronto-basal interhemispheric approach in treating craniopharyngioma were evaluated. In this retrospective study, the safety and effectiveness of fronto-basal interhemispheric approach for surgical resection of craniopharyngioma in 20 patients was analyzed. Of the 20 patients, 12 were men and 8 were women, aged 15–65 years, with an average age of 42.5 years. The course of disease ranged from 1 to 36 months. The craniopharyngioma tumor was completely removed through surgical resection in 18 patients (90%) and partially removed in 2 patients. The pituitary stalk was preserved in 18 patients and 1 patient succumbed during the study period due to large area pulmonary embolism. In conclusion, fronto-basal interhemispheric approach provides better access to the tumor that grows in the sella-hypothalamus and anterior third ventricle region. Using this approach, tumors can be resected while preserving the vital structures such as the pituitary stalk and hypothalamus.

Comparison of surgical exposure and maneuverability associated with microscopy and endoscopy in the retrolabyrinthine and transcrusal approaches to the retrochiasmatic region: a cadaveric study

BACKGROUND

The retrolabyrinthine and transcrusal approaches (RLA and TCA, respectively) are the two most often used posterior transpetrosal approaches that are used to treat lesions in the retrochiasmatic region. Endoscopes are increasingly used in neurosurgical practice. To determine whether a difference exists between the two transpetrosal approaches in the retrochiasmatic region, we evaluated and compared the exposure and maneuverability associated with the microscope and the endoscope in these approaches.

METHODS

Seven formalin-fixed cadaveric heads were dissected bilaterally through the two approaches: four for evaluation and three injected with colored latex for photography. The retrochiasmatic region was divided into four sub-compartments: the compartment before the infundibulum, which was further divided into two parts, (1) the ipsilateral and (2) the contralateral compartments; (3) the retroinfundibulum compartment; (4) the third ventricle. After each approach, exposure and maneuverability of the structures in these four compartments obtained by microscopy and endoscopy were scored under a guidance of a numerical grading system for further comparison.

RESULTS

The TCA provided better exposure and maneuverability at the retrochiasmatic region than the RLA in both the microscopy model [scores of 39.75 ± 2.12 and 32.38 ± 2.56 respectively (p < 0.05)] and the endoscopy model [scores of 82.13 ± 3.40 and 43.75 ± 1.67 respectively (p < 0.05)].

CONCLUSIONS

The TCA is better than the RLA at offering exposure and manipulation to structures in the retrochiasmatic region, especially in patients whose lesion is located high into the third ventricle and/or expanded into the contralateral part. Endoscopes may be helpful in TCA in terms of exposing and maneuvering structures in the contralateral and interpeduncle fossa areas. However, in RLA, not enough room is available for simultaneously maneuvering an endoscope and a surgical instrument.

The Subtemporal Approach to Retroinfundibular Craniopharyngiomas: A New Look at an Old Approach

BACKGROUND

Retrochiasmatic, retroinfundibular craniopharyngiomas are surgically challenging tumors. Anterolateral, posterolateral, and endoscopic endonasal approaches represent the most commonly used techniques to access these tumors, but all require an extensive exposure time, and each has its own risks and limitations. The subtemporal approach is a well-known neurosurgical approach that is rarely described for craniopharyngiomas.

OBJECTIVE

To assess the feasibility, advantages, and disadvantages of a subtemporal approach for craniopharyngiomas.

METHODS

Five patients with retrochiasmatic craniopharyngiomas where the majority of the tumor extended behind the dorsal clival line underwent a subtemporal approach for resection. Extent of resection, degree of temporal lobe injury, visual and endocrine outcomes, and time to recurrence were analyzed.

RESULTS

Average tumor volume was 6.4 cm3. Near-total resection was achieved in 80% (4/5) and subtotal in 20% (1/5). All patients had stable or improved vision. There was 1 new permanent endocrine deficiency. Minimal temporal lobe edema was observed in 80% (4/5) of patients. Three patients required postoperative radiation.

CONCLUSION

The subtemporal approach represents a feasible approach for retrochiasmatic, retroinfundibular craniopharyngiomas when gross total resection is not mandatory. It provides rapid access to the tumor and a caudal-to-cranial visualization that promotes minimal manipulation of critical neurovascular structures, particularly the optic apparatus.

Anatomic comparison of the endonasal and transpetrosal approaches for interpeduncular fossa access

OBJECT

The interpeduncular cistern, including the retrochiasmatic area, is one of the most challenging regions to approach surgically. Various conventional approaches to this region have been described; however, only the endoscopic endonasal approach via the dorsum sellae and the transpetrosal approach provide ideal exposure with a caudal-cranial view. The authors compared these 2 approaches to clarify their limitations and intrinsic advantages for access to the interpeduncular cistern.

METHODS

Four fresh cadaver heads were studied. An endoscopic endonasal approach via the dorsum sellae with pituitary transposition was performed to expose the interpeduncular cistern. A transpetrosal approach was performed bilaterally, combining a retrolabyrinthine presigmoid and a subtemporal transtentorium approach. Water balloons were used to simulate space-occupying lesions. "Water balloon tumors" (WBTs), inflated to 2 different volumes (0.5 and 1.0 ml), were placed in the interpeduncular cistern to compare visualization using the 2 approaches. The distances between cranial nerve (CN) III and the posterior communicating artery (PCoA) and between CN III and the edge of the tentorium were measured through a transpetrosal approach to determine the width of surgical corridors using 0- to 6-ml WBTs in the interpeduncular cistern (n = 8).

RESULTS

Both approaches provided adequate exposure of the interpeduncular cistern. The endoscopic endonasal approach yielded a good visualization of both CN III and the PCoA when a WBT was in the interpeduncular cistern. Visualization of the contralateral anatomical structures was impaired in the transpetrosal approach. The surgical corridor to the interpeduncular cistern via the transpetrosal approach was narrow when the WBT volume was small, but its width increased as the WBT volume increased. There was a statistically significant increase in the maximum distance between CN III and the PCoA (p = 0.047) and between CN III and the tentorium (p = 0.029) when the WBT volume was 6 ml.

CONCLUSIONS

Both approaches are valid surgical options for retrochiasmatic lesions such as craniopharyngiomas. The endoscopic endonasal approach via the dorsum sellae provides a direct and wide exposure of the interpeduncular cistern with negligible neurovascular manipulation. The transpetrosal approach also allows direct access to the interpeduncular cistern without pituitary manipulation; however, the surgical corridor is narrow due to the surrounding neurovascular structures and affords poor contralateral visibility. Conversely, in the presence of large or giant tumors in the interpeduncular cistern, which widen the spaces between neurovascular structures, the transpetrosal approach becomes a superior route, whereas the endoscopic endonasal approach may provide limited freedom of movement in the lateral extension.