Retrosigmoid Suprameatal Approach Research Articles

Retrosigmoid Suprameatal Approach for the Resection of a Petrotentorial and a Petroclival Meningioma: 3-Dimensional Operative Video

Posterior skull base meningiomas pose a formidable surgical challenge because of their proximity to critical neurovascular structures and the narrow corridor available for their resection. While radiosurgery may be an effective treatment alternative, 1 microsurgery remains superior in addressing associated compressive symptoms. 2 Several approaches have been described to access these lesions, with varying degrees of exposure to the petroclival region. 3-7 The choice of the optimal approach depends on different factors related to the tumor morphological features and the surgeon's preference and experience. The retrosigmoid approach is a straightforward procedure compared with other more laborious skull base approaches to the petroclival region. Its described intradural extensions contribute to its high versatility for posterior skull base tumors. One of these extensions involves drilling the suprameatal tubercle, significantly increasing exposure and maneuverability for tumors located medial to the internal acoustic canal. 8 The semisitting position adds further value as it allows for a gravity-assisted clearance of blood and debris, achieving a clear surgical field. 9 We present 2 patients suffering from trigeminal neuralgia secondary to a petrotentorial and a petroclival meningioma. Given the location of both tumors predominantly medial and superior to the internal acoustic canal, resection was carried out through a retrosigmoid suprameatal approach with the patient in a semisitting position. Relevant anatomic and surgical considerations are discussed and illustrated in this 3-dimensional operative video. Gross total resection was achieved, and both patients remained neurologically intact and pain-free at long-term follow-up. Both patients consented to the procedure and to the publication of their image.

Retrosigmoid Suprameatal Approach for Resection of Petrotentorial Cerebellopontine Angle Meningioma: Operative Video and Technical Nuances.

Meningiomas are the second most common tumor to arise in the cerebellopontine angle. In this operative video atlas manuscript, the authors demonstrate a step-by-step technique for microsurgical resection of a petrotentorial meningioma in the cerebellopontine angle via a retrosigmoid suprameatal approach. Drilling of the hyperostotic suprameatal tubercle was necessary to gain access to the dural origin and anterior petrosal extent of the tumor. The nuances of microsurgical and skull base technique are illustrated including microsurgical dissection of the tumor away from the brainstem and neurovascular structures, facial nerve preservation, and fat graft-assisted Medpor Titan reconstruction to prevent cerebrospinal fluid leakage. A gross total resection was achieved, and the patient was neurologically intact. In summary, the retrosigmoid suprameatal approach is an important strategy in the armamentarium for surgical management of petrotentorial meningiomas in the cerebellopontine angle. The link to the video can be found at: https://youtu.be/kwQP6BSYK7U .

Trochlear Nerve Repair during Retrosigmoid Suprameatal Approach for Petrotentorial Meningioma: Operative Video.

When operating on difficult skull base lesions, it is essential to be able to handle unexpected intraoperative findings or troubles, while achieving maximal lesion removal and minimal functional deficit. This video demonstrates a case of trochlear nerve repair that was performed during the retrosigmoid suprameatal approach for treatment of a petrotentorial meningioma, extending into the Meckel's cave. The patient is a 47-year-old woman with a right petrotentorial meningioma, extending into the Meckel's cave. The retrosigmoid suprameatal approach was performed with preservation of the superior petrosal vein. However, a divided trochlear nerve was incidentally found during tumor resection. We hence carefully dissected both nerve ends from the tumor without shortening their lengths, and repaired them by end-to-end anastomosis, using fibrin glue without any graft materials. The tumor was removed completely and the patient's preoperative facial sensory impairment disappeared after the surgery. The patient's facial sensory impairment disappeared completely, but she had transient diplopia after the surgery. However, the newly developed diplopia resolved completely, and she had no neurological deficits or tumor recurrence during the follow-up period of 1-year. The link to the video can be found at: https://youtu.be/g-B-w_zDudg .

Presigmoid Approach to Dumbbell Trigeminal Schwannoma.

This case is a 15-year-old male, presenting with headaches, right face, and arm numbness, and ataxia. MRI (magnetic resonance imaging) revealed a large right sided dumbbell shaped lesion, extending into the middle and posterior fossa with compression of the brainstem consistent with a trigeminal schwannoma. Treatment options here would be a retrosigmoid suprameatal approach or a lateral presigmoid approach. Given the tumor extension into multiple compartments, a presigmoid craniotomy, combining a middle fossa approach with anterior petrosectomy, and retrolabyrinthine approach with posterior petrosectomy were used to maximize the direct access corridor for resection. The petrous apex was already expanded and remodeled by the tumor. Nerve fascicles preservation technique is paramount to the functional preservation of the trigeminal nerve. The extent of resection should be weighed against the anatomical functional integrity of the nerve. Near total resection is considered if that means more nerve preservation. Postoperatively, the patient had a slight (House–Brackman grade II) facial droop, which resolved over days and developed right trigeminal hypesthesia at several weeks. This case is presented to demonstrate a combined petrosectomy technique for resection of lesions extending into both the middle and posterior cranial fossa with near total resection and trigeminal nerve preservation. The link to the video can be found at: https://youtu.be/kA9GyFhL1dg .

Two step approach for surgical removal of petroclival meningiomas with large supratentorial extension

The treatment of petroclival meningiomas is still a matter of controversy in literature. In the last decades, many approaches have been introduced. Our strategy for the treatment of such tumors having large supratentorial extension with encasement of the internal carotid artery or compression of optic and oculomotor nerves has evolved in the attempt to improve the outcome. Currently, we favor a surgical technique consisting of two steps. As first step, we perform a retrosigmoid suprameatal approach in order to resect the posterior part of the tumor and obtain brainstem decompression. In the second step, carried out after patient's recovery from the first surgery, we remove the supratentorial portion of the lesion using a frontotemporal craniotomy to achieve the decompression of the optic nerve, oculomotor nerve, and carotid artery. The retrosigmoid suprameatal approach allows for adequate brainstem decompression: the tumor itself creates a surgical channel increasing the accessibility to the lower and upper petroclival surface. Moreover, this route allows for early visualization of cranial nerves in the posterior fossa and safe tumor removal under direct visual control, reducing the risk of postoperative deficits. Via the simple and safe frontotemporal craniotomy, the supratentorial part of the lesion can be removed thus avoiding the need of invasive approaches. We propose a two-stage surgery for treatment of petroclival meningiomas combining two simple routes such as retrosigmoid suprameatal and frontotemporal craniotomy. This approach reflects our philosophy to use simple and less invasive approaches in order to preserve neurological function and a good quality of life of the patient.

The retrosigmoid intradural suprameatal approach to posterior cavernous sinus – Microsurgical anatomy

Objective The retrosigmoid intradural suprameatal approach includes the standard retrosigmoid suboccipital route with drilling of the petrous bone above and anterior of the internal auditory meatus, allowing for exposure of the trigeminal nerve within the Meckel's cave and of the middle fossa. In this study, the authors analyzed the potential use of an extended variation of the suprameatal route to approach the posterior cavernous sinus for microsurgery of, e.g., petroclival meningiomas and trigeminal schwannomas. Methods The microsurgical anatomy of the retrosigmoid suprameatal approach was examined by using 10 adult cadaveric specimens (20 sides), using 3–40× magnification. The exposure to the posterior cavernous sinus provided by this approach was focused. Results After drilling the suprameatal tubercle toward the petrous apex, the Meckel's cave was exposed. The trochlear nerve was the landmark for opening the cavernous sinus by this approach. The dura located medially to the entry point of the trochlear nerve into the tentorium was resected, allowing exposure of the intracavernous carotid artery with its meningohypophyseal trunk. Conclusion The extended retrosigmoid intradural suprameatal approach allows exposure of the posterior cavernous sinus and may be used to remove lesions of the posterior fossa extending into the Meckel's cave and into the cavernous sinus.

Microsurgical anatomy of the superior petrosal venous complex: new classifications and implications for subtemporal transtentorial and retrosigmoid suprameatal approaches

The purpose of this study was to define the patterns of drainage of the superior petrosal venous complex (SPVC) along the petrous ridge in relation to the Meckel cave and internal acoustic meatus (IAM) and to delineate its effect on the surgical exposures obtained in subtemporal transtentorial and retrosigmoid suprameatal approaches. The patterns of drainage of the SPVC along the petrous ridge were characterized according to their relation to the Meckel cave and the IAM based on an examination of 30 hemispheres. Subtemporal transtentorial and retrosigmoid suprameatal approaches were performed in three additional cadavers to demonstrate the effect of the drainage pattern on the surgical exposures. The SPVC emptied into the superior petrosal sinus (SPS) within a distance of 1 cm from the midpoint of the Meckel cave. The patterns of drainage of the SPVC were classified into three groups. Type I emptied into the SPS above and lateral to the boundaries of the IAM. The most common type, Type II, emptied between the lateral limit of the trigeminal nerve at the Meckel cave and the medial limit of the facial nerve at the IAM, within an area of approximately 13 mm. Type III emptied into the SPS above or medial to the Meckel cave. The ideal SPVC for a subtemporal transtentorial approach (with or without anterior extradural petrosectomy) seems to be a Type I. In SPVC Type III and those Type II cases in which the SPVC is located near the Meckel cave, the amount of working space is significantly limited in a subtemporal transtentorial approach. In contrast, the ideal type of SPVC for a retrosigmoid suprameatal approach would be a Type III, and the SPVC must be divided in the majority of Type I and II cases for a satisfactory surgical exposure along the Meckel cave and middle fossa dura. The proposed modified classification system and its effect on the surgical exposure may aid in planning the approach directed along the petrous apex and may reduce the probability of venous complications.