Endoscope-assisted Retrosigmoid Research Articles

Retrosigmoid versus Retrolabyrinthine Posterior Petrosal Route to the Petroclival Area: Quantitative Assessment of Endoscope-Assisted Approaches and Correlations with Morphometric Features

Using a cadaveric model, we compared endoscope-assisted retrosigmoid (EAR) and endoscope-assisted retrolabyrinthine posterior petrosal (EARPP) approaches towards the petroclival area, regarding surgical exposure and instrument maneuverability, also verifying how some petroclival morphometric parameters correlate with these variables. In five cadaver heads, EAR approach was performed on one side and EARPP on the other (10 approaches). Under endoscopic view, neuronavigation coordinates were acquired to compute areas of exposure (petroclival and pontomedullary) and maneuverability at Dorello's canal entrance to run the comparison. Correlations of these variables with petroclival angle and clival depth were also analyzed. EAR and EARPP showed equivalence regarding surgical exposure (petroclival: 365.85 ± 133.12 mm2 and 320.62 ± 103.44 mm2, respectively, P= 0.69; pontomedullary: 255.83 ± 88.26 mm2 and 229.80 ± 74.39 mm2, respectively, P= 0.83), but EAR afforded greater maneuverability at Dorello's canal (1155.88 ± 134.35 mm2, P= 0.03). The petroclival angle and clival depth showed different strong correlations with maneuverability depending upon the route, but not with surgical exposure in both approaches. Endoscopic techniques can spare the need for additional steps of greater morbidity when approaching the petroclival area in both routes. A simpler and faster approach as EAR was favored over EARPP in this standardized quantitative assessment. The petroclival angle and clival depth may interfere with maneuverability, but not with surgical exposure in both endoscope-assisted approaches.

Trigeminal neuralgia: updated management

The so-called idiopathic trigeminal neuralgia is easily diagnosed by the clinical history of the patient and present a constant cause, a neurovascular conflict in the cerebellopontine angle in the majority of cases, which is clearly identified by MRI assessment. Knowing the cause, after a trial period with a medical treatment, a curative surgical solution can be now offered to the patient when the medications do not provide a pain-free result or when the patients wish a more definitive solution. Combining the use of both operating microscope and endoscope increases the efficiency of the neurovascular decompression and decreases drastically the potential morbidity of the surgical procedure. From 355 patients suffering of trigeminal neuralgia who underwent endoscope-assisted retrosigmoid approach, the authors present their experiences and results.

Endoscope-Assisted Retrosigmoid Approach for Cerebellopontine Angle Epidermoid Tumor.

Objectives Surgical resection is the only effective treatment modality for epidermoid tumors. Complete resection with preservation of neurological function must be pursued whenever possible, because it offers a cure for patients. However, the inability to identify hidden remnants, interdigitating around cranial nerves, especially in larger tumors, may be a contributing factor for incomplete resection. This operative video demonstrates the technical nuances in achieving complete resection of a cerebellopontine angle epidermoid tumor via an endoscope-assisted retrosigmoid approach. Design and Setting Operative video of an endoscope-assisted retrosigmoid, approach for complete resection of a cerebellopontine angle epidermoid tumor. The patient was a 16-year-old female, who presented with 1-year history of worsening headaches and imbalance. Her neurological exam was normal, including normal cranial nerve function, and hearing. Radiological evaluation revealed an epidermoid tumor in the right cerebellopontine angle, extending to the interpeduncular cistern. Surgical resection was recommended. Given extension of the tumor across the midline, an endoscope-assisted procedure was planned to increase the odds of complete resection. Results The video demonstrates the surgical technique applied for tumor resection. The patient's clinical symptoms resolved completely after surgery and she remained neurologically intact. Postoperative magnetic resonance imaging (MRI) confirmed complete tumor resection. There were no postoperative complications. Conclusions The use of endoscopic techniques for resection of cerebellopontine angle epidermoid tumor is safe and effective and may increase the odds of complete resection, especially in larger tumors spreading across the midline, by enabling the surgeon clear visualization of deep-seated and contralateral relevant neurovascular structures, not readily accessible by the surgical microscope. The link to the video can be found at: https://youtu.be/X6YP_7OeQQE .

Resection of a Petroclival Meningioma via the Endoscope-Assisted Retrosigmoid Approach: 2-D Operative Video.

We present a case of a petroclival meningioma that was resected through an endoscope-assisted retrosigmoid approach via corridors above and below the facial-vestibulocochlear nerve complex. The patient is a 61-year-old female with complaints of left-sided hypesthesia and neuralgia of the infraorbital and zygomatic region, intermittent periorbital myokymia, and a slight facial palsy (HB II). This 2D video demonstrates the operative technique, anatomical and surgical nuances of the skull base approach and microdissection of the tumor from the critical neurovascular structures. A gross total resection was achieved. The patient’s facial and trigeminal symptoms resolved completely within a few weeks. At 2 year follow up there was no indication of residual or recurrence.In summary, the retrosigmoid approach with endoscopic assistance is an important and powerful tool in the armamentarium for the microsurgical management of meningiomas of the lateroventral skullbase of the posterior fossa. The link to the video can be found at: https://youtu.be/Px4XIRDoALc .

Endoscope-assisted retrosigmoid approach in hemifacial spasm: our experience

IntroductionThe use of surgical decompression of facial hemispasm due to the loop in the internal auditory canal is not always accepted due to the risk related to the surgical procedure. Currently a new surgical technique allows surgeons to work in safer conditions. ObjectiveTo report the results with endoscope-assisted retrosigmoid approach for facial nerve microvascular decompression in hemifacial spasm due to neurovascular conflict. The surgical technique is described. MethodsWe carried out a prospective study in a tertiary referral center observing 12 (5 male, 7 female) patients, mean age 57.5 years (range 49–71) affected by hemifacial spasm, that underwent to an endoscope assisted retrosigmoid approach for microvascular decompression. We evaluated intra-operative findings, postoperative HFS resolution and complication rates. ResultsHemifacial spasm resolution was noticed in 9/12 (75%) cases within 24h after surgery and in 12/12 (100%) subjects within 45 days. A significant (p<0.001) correlation between preoperative historical duration of hemifacial spasm and postoperative recovery timing was recorded. Only 1 patient had a complication (meningitis), which resolved after intravenous antibiotics with no sequelae. No cases of cerebrospinal fluid leak, facial palsy or hearing impairment were recorded. Hemifacial spasm recurrence was noticed in the only subject where the neurovascular conflict was due to a vein within the internal auditory canal. ConclusionsThe endoscope assisted retrosigmoid approach technique offers an optimal visualization of the neurovascular conflict thorough a minimally invasive approach, thus allowing an accurate decompression of the facial nerve with low complication rates. Due to the less invasive nature, the procedure should be considered in functional surgery of the cerebellar pontine angle as hemifacial spasm treatment, specially when the procedure is performed by an otolaryngologist.

Applied anatomy of the cerebelloponotine angle through retrosigmoid approach

Objective:To privde anatomical basis for the surgical operation of endoscope-assisted retrosigmoid approach. Method:In 20 adult head cadavers fixed with formalin (40 sides), the surgery via retrosigmoid approach was simulated. The anatomic features of the cerebellopontine angle were examined and measured. Result:The distance from the midpoint of posterior border of sigmoid sinus to acoustic nerve near internal acoustic pore, trigeminal nerve near Meckel's cave, glossopharyngeal nerve near jugular foramen and the posterior margin of internal acoustic meatus were (32.8±1.7)mm, (46.3±1.8)mm, (29.4±3.0)mm, (31.2±2.0)mm. The tracks of degree of angle of median sagittal plane were (32.6±7.7)°, (31.4±4.1)°, (40.2±6.9)°, (32.7±4.9)°. Conclusion:The measurement provides some useful references for defining the position in operating.

Surgical Treatment of Jugular Foramen Schwannoma: Surgical Treatment Based on a New Classification.

Surgery plays a crucial role in the management of jugular foramen schwannomas (JFSs). Still, it remains challenging, particularly in cases of tumor growth inside the bony canal of the jugular foramen (JF). To present our recent experience with surgical treatment of JFSs, with particular focus on the efficacy and safety of the endoscope-assisted retrosigmoid infralabyrinthine and transcervical approaches for tumors extending through the JF bony canal. Sixteen consecutive patients with JFSs were retrospectively evaluated. Tumor extension was classified using a modification of our previous classification, and surgical approach was selected accordingly. The extent of tumor resection, cranial nerve outcome, approach-related morbidities, and recurrence of the tumors were documented. Four cases of JFSs were subtotally resected elsewhere and 12 were primary. The most common type was B2 (6 cases). The average tumor size was 38.5 mm. Gross total resection was achieved in all patients, and none recurred during follow-up. There was no operative mortality or new permanent neurological deficits. A postoperative cerebrospinal fluid leak developed in 2 patients, 1 managed with lumbar drain and the other with wound revision. The preoperative swallowing difficulty temporarily deteriorated in 3 patients, but recovered well within the first 2 postoperative weeks in all 3. Improvement of the preoperative lower cranial nerve dysfunction was observed in 5 patients. The surgical approach selection to JFSs should be tailored individually to their extension pattern. The judicious application of endoscope-assisted retrosigmoid infralabyrinthine and transcervical techniques allow for safe and more radical removal of JFSs with a major intraosseous part.

Microsurgical and endoscopic anatomy of the extended retrosigmoid inframeatal infratemporal approach.

Different and often complex routes are available to deal with jugular foramen tumors with extracranial extension. To describe a novel extension of the retrosigmoid approach useful to expose the extracranial area abutting the posterior fossa skull base. A navigation-guided, endoscope-assisted retrosigmoid inframeatal approach was performed on 6 cadaveric heads in the semisitting position, displaying an area from the internal acoustic meatus to the lower cranial nerves and exposing the intrapetrous internal carotid artery. We then continued removing the temporal bone located between the sigmoid sinus and the hearing apparatus, reaching the infratemporal area just lateral to the jugular fossa. This drilling, which we refer to as posterolateral inframeatal drilling, has not previously been described. Drilling of the horizontal segment of the occipital squama allowed good visualization of the uppermost cervical internal carotid artery, internal jugular vein, and lower extracranial cranial nerves. We were able to provide excellent exposure of the inframeatal area and of the posterior infratemporal fossa from different operative angles, preserving the neurovascular structures and the labyrinth in all specimens. The intradural operative window on the extracranial compartment was limited by the venous sinuses and the hearing apparatus and presented a mean width of 8.52 mm. Sigmoid sinus transection led to better visualization of the lateral half of the jugular foramen and of the uppermost cervical internal carotid artery. The navigation-guided endoscope-assisted extended retrosigmoid inframeatal infratemporal approach provides an efficient and versatile route for resection of jugular foramen tumors with extracranial extension.

A combined dual-port endoscope-assisted pre- and retrosigmoid approach to the cerebellopontine angle: an extensive anatomo-surgical study.

The use of the endoscope in the cerebellopontine angle (CPA) has been suggested to minimize cerebellar retraction and reduce the size of the craniotomy. 3D endoscopy combines the benefits of conventional 2D endoscopy with the added benefit of stereoscopic perception, though improved visualization alone does not guarantee improved surgical maneuverability and a better surgical outcome. We propose a new combined dual-port endoscope-assisted pre- and retrosigmoid approach to improve visualization and accessibility of the CPA with shortened distances and increased surgical maneuverability of neurovascular structures. We analyze surgical exposure and maneuverability of this approach and compare it with the surgical microscopic and a conventional single-port endoscope-assisted retrosigmoid approach. This combined pre- and retrosigmoid approach was performed on eight cadaveric heads (16 sides). The endoscopic probe was inserted through the presigmoid surgical port while surgical manipulation was performed through the retrosigmoid corridor. The CPA was divided into three compartments, from medial to lateral, the anteromedial, and the middle and the posterolateral. The microscope provided good visualization of the posterolateral and middle compartments, whereas poor visualization was offered of the anteromedial compartment. The dual-port endoscopic approach dramatically improved visualization and surgical maneuverability of the anteromedial compartments, clivus, and related neurovascular structures. Additionally, the 3D endoscope allowed for a better understanding of the surgical anatomy of the CPA and improved visualization of structures located in the anteromedial compartments towards the midline. This approach allowed for full realization of the benefits of endoscopic-assisted technique by improving surgical access and maneuverability.

Endoscope-assisted retrosigmoid keyhole approach for cerebellopontine angle: cadaveric study

Conclusion: A 20 mm hole made backwards from the midpoint of the asterion to the mastoid process is suitable for a retrosigmoid keyhole approach with the aid of an endoscope. The endoscope-assisted retrosigmoid keyhole approach can be considered an effective and safe method for removal of vestibular schwannoma. Objective: To investigate the feasibility of the endoscope-assisted retrosigmoid keyhole approach for exposing the cerebellopontine angle (CPA) and internal auditory canal (IAC). Methods: With the aid of an endoscope, we simulated surgical procedures in 30 sides of 15 formalin-fixed cadaver heads. Results: (1) For 24 (80%) sides, the midpoint of the top notch to the mastoid process was in the anterior edge of the sigmoid sinus; for 27 sides (90%) the midpoint of the asterion to the mastoid process was in the posterior edge of the sigmoid sinus. (2) The IAC and CPA were exposed by the retrosigmoid keyhole approach with the aid of the endoscope.

Endoscope-assisted retrosigmoid intradural suprameatal approach to the middle fossa: Anatomical and surgical considerations

Introduction Lesions involving the posterior and middle fossa may be reached by several surgical approaches depending mostly on tumors' location and characteristics. The retrosigmoid intradural suprameatal approach has been used to remove tumors of the posterior fossa extending into Meckel's cave and the middle fossa. With large tumors, this approach may allow exposure of the oculomotor and optic nerves, the supraclinoid internal carotid and communicating posterior arteries. Methods Three formaldehyde-fixed specimens have been prepared on both sides using the conventional retrosigmoidal-suprameatal approach. The entire endoscopic preparations have been documented via a digital recording system, using a 5 mm endoscope with a 25° perspective. The authors describe the anatomical corridor and technique of the endoscope-assisted retrosigmoid intradural suprameatal approach to lesions that are located predominantly within the posterior fossa and supratentorial extension into Meckel's cave, sellar and parasellar region. Conclusions The endoscope-assisted suprameatal approach provides exposure of the antero-medial middle fossa even in cases of skull base lesions that have not caused significant displacement of neurovascular structures.