Posterior Transpetrosal Approach Research Articles

Usefulness of Posterior Transpetrosal Approach for Paramedian Vascular Lesions

Usefulness of Posterior Transpetrosal Approach for Paramedian Vascular Lesions

Transpetrosal Routes to the Skull Base-Anterior and Posterior Transpetrosal Approaches.

The extended middle fossa approach with anterior petrosectomy, or anterior transpetrosal approach, is a highly effective and direct approach to difficult-to-access petroclival tumors and basilar artery aneurysms. This surgical approach exposes a significant window of the posterior fossa dura between the mandibular nerve, internal auditory canal, and petrous internal carotid artery, below the level of the petrous ridge, and provides an unobstructed view of the middle fossa floor to the upper half of the clivus and petrous apex, without requiring removal of the zygoma. The posterior transpetrosal approaches, including the perilabyrinthine, translabyrinthine, and transcochlear approaches, provide direct and wide exposure of the cerebellopontine angle and posterior petroclival region. The translabyrinthine approach is commonly used for the removal of acoustic neuromas and other lesions of the cerebellopontine angle. We provide a stepwise description of how we perform these approaches and how to combine and extend them in order to achieve transtentorial exposure.

Posterolateral Routes to the Skull Base, Craniocervical Junction, and Jugular Foramen-The Far Lateral Transcondylar Approach and Combined Transpetrosal Transcervical Approaches.

The far lateral approach provides wide surgical access to the lower third of the clivus, pontomedullary junction, and anterolateral foramen magnum and rarely requires craniovertebral fusion. The most common indications for this approach are posterior inferior cerebellar artery and vertebral arteryaneurysms, brainstem cavernous malformations, and tumors anterior to the lower pons and medulla, including meningiomas of the anterior foramen magnum, schwannomas of the lower cranial nerves, and intramedullary tumors at the craniocervical junction. We provide a stepwise description of how we perform the far lateral approach, as well as how to combine the far lateral approach with other skull base approaches, including the subtemporal transtentorial approach, for lesions involving the upper clivus; the posterior transpetrosal approach, for lesions involving the cerebellopontine angle and/or petroclival region; and/or lateral cervical approaches, for lesions involving the jugular foramen or carotid sheath regions.

Posterior Transpetrosal Approaches to the Posterior Cranial Fossa: radiological preoperative assessment and microneurosurgical anatomy

Posterior Transpetrosal Approaches to the Posterior Cranial Fossa: radiological preoperative assessment and microneurosurgical anatomy

Microsurgical anatomy and surgical exposure of the cerebellar peduncles.

A better understanding of the surgical anatomy of the cerebellar peduncles in different surgical approaches and their relationship with other neural structures are delineated through cadaveric dissections. We aimed to revisit the surgical anatomy of the cerebellar peduncles to describe their courses along the brain stem and the cerebellum and revise their segmental classification in surgical areas exposed through different approaches. Stepwise fiber microdissection was performed along the cerebellar tentorial and suboccipital surfaces. Multiple surgical approaches in each of the cerebellar peduncles were compared in eight silicone-injected cadaveric whole heads to evaluate the peduncular exposure areas. From a neurosurgical point of view, the middle cerebellar peduncle (MCP) was divided into a proximal cisternal and a distal intracerebellar segments; the inferior cerebellar peduncle (ICP) into a ventricular segment followed by a posterior curve and a subsequent intracerebellar segment; the superior cerebellar peduncle (SCP) into an initial congregated, an intermediate intraventricular, and a distal intramesencephalic segment. Retrosigmoid and anterior petrosectomy approaches exposed the junction of the MCP segments; telovelar, supratonsillar, and lateral ICP approaches each reached different segments of ICP; paramedian supracerebellar infratentorial, suboccipital transtentorial, and combined posterior transpetrosal approaches displayed the predecussation SCP within the cerbellomesencephalic fissure, whereas the telovelar approach revealed the intraventricular SCP within the superolateral recess of the fourth ventricle. Better understanding of the microsurgical anatomy of the cerebellar peduncles in various surgical approaches and their exposure limits constitute the most critical aspect for the prevention of surgical morbidity during surgery in and around the pons and the upper medulla. Our findings help in evaluating radiological data and planning an operative procedure for cerebellar peduncles.

Petroclival Meningiomas: A Simple System That Could Help in Selecting the Approach.

BACKGROUNDPetroclival meningiomas (PCM) represent a neurosurgical challenge due to their strategic location close to the brainstem.OBJECTIVETo assess the applicability of a retrosigmoid approach (RSA) by analyzing the degree of displacement of the middle cerebellar peduncle (MCP) elicited by PCM.METHODSPatients with PCM were prospectively included and divided into those whose imaging studies showed that the posterior end of the MCP was displaced by the tumor and were eligible for and underwent RSA (group A) and those who were not eligible for RSA and who underwent surgery via a posterior transpetrosal approach (group B). We compared tumor behavior, clinical characteristic of patients and surgical results.RESULTSTwenty patients with PCM were enrolled and allocated to group A (n = 15) or group B (n = 5). The clinical manifestations were more severe in group B; tumors in this group were larger and gross total removal was achieved in only 1 patient (20%). In comparison, in 12 cases on group A, tumors could be totally removed (80%) and all of these patients could recover their quality of life after surgery.CONCLUSIONTo our knowledge, this study is the first to consider displacement of the MCP when establishing a suitable surgical approach for PCM. Our results suggest that the RSA becomes increasingly suitable when peduncle displacement is greater. By using this method, it was also possible to identify two types of tumors: petroclivals (group A) and clivopetrosals (group B), that show some specific clinical and surgical differences.

Petroclival meningiomas: long-term outcomes of multimodal treatments and management strategies based on 30 years of experience at a single institution.

A thorough investigation of the long-term outcomes and chronological changes of multimodal treatments for petroclival meningiomas is required to establish optimal management strategies. The authors retrospectively reviewed the long-term clinical outcomes of patients with petroclival meningioma according to various treatments, including various surgical approaches, and they suggest treatment strategies based on 30 years of experience at a single institution. Ninety-two patients with petroclival meningiomas were treated surgically at the authors' institution from 1986 to 2015. Patient demographics, overall survival, local tumor control rates, and functional outcomes according to multimodal treatments, as well as chronological change in management strategies, were evaluated. The mean clinical and radiological follow-up periods were 121 months (range 1-368 months) and 105 months (range 1-348 months), respectively. A posterior transpetrosal approach was most frequently selected and was followed in 44 patients (48%); a simple retrosigmoid approach, undertaken in 30 patients, was the second most common. The initial extent of resection and following adjuvant treatment modality were classified into 3 subgroups: gross-total resection (GTR) only in 13 patients; non-GTR treatment followed by adjuvant radiosurgery or radiation therapy (non-GTR+RS/RT) in 56 patients; and non-GTR without adjuvant treatment (non-GTR only) in 23 patients. The overall progression-free survival rate was 85.8% at 5 years and 81.2% at 10 years. Progression or recurrence rates according to each subgroup were 7.7%, 12.5%, and 30.4%, respectively. The authors' preferred multimodal treatment strategy, that of planned incomplete resection and subsequent adjuvant radiosurgery, is a feasible option for the management of patients with large petroclival meningiomas, considering both local tumor control and postoperative quality of life.

Surgical Strategies for Ruptured Complex Aneurysms Using Skull Base Technique and Revascularization Surgeries.

Object:Surgical clipping of paraclinoid aneurysm, thrombosed large aneurysm, and/or vertebral-basilar dissecting aneurysms can be very difficult and has relatively high morbidity. We describe our experience using skull base and bypass technique and discuss the advantages and its pitfalls.Patients and Methods:We retrospectively reviewed medical charts of 22 consecutive patients with complex aneurysmal lesions underwent skull base and/or bypass techniques between March 2012 and April 2017.Results:There were 5 patients with paraclinoid or internal carotid artery (ICA) aneurysm underwent modified extradural temporopolar approach with mini-peeling of the dura propria with suction decompression, 3 patients with ICA aneurysm underwent intradural anterior clinoidectomy, 12 patients with vertebral dissecting aneurysm through transcondylar fossa approach (6 patients underwent occipital artery-posterior inferior cerebellar artery [OA-PICA] bypass), 1 patients with vertebral artery dissection underwent superficial temporal artery-superior cerebellar artery and OA-PICA bypass through posterior transpetrosal approach, 1 patient with arteriovenous fistula at the ventral side of the craniovertebral junction through extremely far lateral approach. Surgical outcome was good recovery in 10 patients, moderate disability in 4, severe disability in 4, vegetative state in 2, and dead is 2 patients. The favorable outcome was 63.6%, and poor outcome was 36.4%, which showed poor grade subarachnoid hemorrhagic patients. No patient suffered any complication related to re-rupture and/or incomplete clipping.Conclusion:Skull base technique, which can create a wide and shallow operative space, allowed us to improve surgical outcome and to reduce the risk of intraoperative neurovascular injury for surgical treatment of deeply located complex aneurysms.

The Posterior Transpetrosal Approach in a Case of Large Retrochiasmatic Craniopharyngioma: Operative Video and Technical Nuances.

Objectives To discuss the use of the posterior petrosal approach for the resection of a retrochiasmatic craniopharyngioma. Design Operative video. Results In this case video, the authors discuss the surgical management of a large craniopharyngioma, presenting with mass effect on the third ventricle and optic apparatus. A first surgical stage, through an endoscopic endonasal transtubercular approach, allowed satisfactory decompression of the optic chiasma and nerves in preparation for adjuvant therapy. However, accelerated growth of the tumor, with renewed visual deficits and mass effect on the hypothalamus and third ventricle, warranted a supplementary resection. A posterior transpetrosal 1 2 (also called “retrolabyrinthine transtentorial”) was performed to obtain a better exposure of the tumor and the surrounding anatomy (floor and walls of the third ventricle, perforating vessels, optic nerves, etc.) 3 . Nuances of technique and surgical pearls related to the posterior transpetrosal are discussed and illustrated in this operative video, including the posterior mobilization of the transverse–sigmoid sinuses junction, preservation of the venous anatomy during the tentorial incision, identification and preservation of the floor of the third ventricle during tumor resection, and a careful multilayer closure. Conclusion Retrochiasmatic craniopharyngiomas are difficult to reach tumors that often require skull base approaches, either endoscopic endonasal or transcranial. The posterior transpetrosal approach is an important part of the surgical armamentarium to safely resect these complex tumors. The link to the video can be found at: https://youtu.be/2MyGLJ_v1kI .

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

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. 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. 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)]. 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.

Superficial temporal artery to proximal posterior cerebral artery bypass through the anterior temporal approach.

Background:The superficial temporal artery (STA) to proximal posterior cerebral artery (PCA) (P2 segment) bypass is one of the most difficult procedures to perform because the proximal PCA is located deep and high within the ambient cistern. STA to proximal PCA bypass is usually performed through a subtemporal approach or posterior transpetrosal approach, and rarely through a transsylvian approach. The aim of this study was to describe the operative technique of STA to proximal PCA bypass through a modified transsylvian approach (anterior temporal approach).Methods:STA to proximal PCA bypass was performed through an anterior temporal approach in three patients with intracranial aneurysm. We describe the details of the surgical technique.Results:The STA was successfully anastomosed to the proximal PCA in all cases. One patient suffered hemiparesis and aphasia due to infarction in the anterior thalamoperforating artery territory.Conclusions:STA to proximal PCA bypass can be performed through an anterior temporal approach in selected patients. We recommend that every precaution, including complete hemostasis, placement of cellulose sponges beneath the recipient artery to elevate the site of the anastomosis, and placement of a continuous drainage tube at the bottom of the operative field to avoid blood contamination during the anastomosis, should be taken to shorten the temporary occlusion time.

Trautmann's triangle anatomy with application to posterior transpetrosal and other related skull base procedures

Trautmann's triangle (TT) faces the cerebellopontine angle and is exposed during posterior transpetrosal approaches. However, reports on the morphometric analysis of this structure are lacking in the literature. The goal was to better understand this important operative corridor. TT was exposed from an external approach (transmastoid) in ten cadavers (20 sides) and from an internal approach on 20 dry adult temporal bones. Measurements included calculation of the area of TT and the distance of the endolymphatic sac from the anterior border of the sigmoid sinus. The area range of TT was 45-210 mm(2) (mean 151 mm(2); SD 37 mm(2)). Three types of triangles were identified based on area. Type I triangles had areas less than 75 mm(2), Type II areas were 75-149 mm(2), and Type III areas were 150 mm(2) and greater. These types were observed in 37.5%, 35%, and 27.5% of sides, respectively. The distance from the jugular bulb's anterior border to the posterior border of the posterior semicircular canal ranged from 6 to 11 mm (mean 8.5 mm). The endolymphatic sac was located in the inferior portion of TT and traveled anterior to the sigmoid sinus. The horizontal distance from the anterior edge of the sigmoid sinus to the posterior edge of the endolymphatic sac ranged from 0 to 13.5 mm (mean 9 mm). Additional anatomic knowledge regarding TT may improve neurosurgical procedures in this region by avoiding intrusion into the endolymphatic sac and sigmoid sinus.

A suggestion of modified classification of trigeminal schwannomas according to location, shape, and extension.

BackgroundComprehensive knowledge of the anatomical features of trigeminal schwannomas (TSs) is essential in planning surgery to achieve complete tumor resection. In the current report, we propose a modified classification of TSs according to their location of origin, shape, and extension into the adjacent compartment, and discuss appropriate surgical strategies with this classification.MethodsWe retrospectively analyzed 49 patients with TS who were treated surgically by a single neurosurgeon at the Asan Medical Center between 1993 and 2013.ResultsThere were 22 males and 27 females, with the median age of 40 years (range, 21-75 years). Median tumor size was 4.0 cm in diameter (2.0-7.0 cm). Tumors were classified as follows: Type M (confined to the middle fossa; 8 cases, 19.0%), P (confined to the posterior fossa; 2 cases, 4.8%), MP (involving equally both middle and posterior fossae; 5 cases, 11.9%), Mp (predominantly middle fossa with posterior fossa extension; 6 cases, 14.3%), Pm (predominantly posterior fossa with middle fossa extension; 16 cases, 38.1%), Me (predominantly middle fossa with extracranial extension; 4 cases, 9.5%). Surgical approach was chosen depending on the tumor classification. More specifically, a frontotemporal craniotomy and extradural approach with or without zygomatic or orbitozygomatic osteotomy was applied to M- or Mp-type tumors; a lateral suboccipital craniotomy with or without suprameatal approach was applied to the majority of P- or Pm-type tumors; and a posterior transpetrosal approach was used in four tumors (three Pm and one MP). Gross total resection was achieved in 95.9% of patients, and the overall recurrence rate was 4.1% (2 patients). Postoperatively, trigeminal symptoms were improved or unchanged in 51.0% of cases (25 patients). Surgical complications included meningitis (5 patients) and cerebrospinal fluid leakage (3 patients). There was no mortality.ConclusionTSs are well to be classified with our modified classification and able to be removed effectively and safely by selecting appropriate surgical approaches.

Double Plombage Using Abdominal Adipose Tissue for Posterior Transpetrosal Approach–induced Liquorrhea

Objective: To prevent posterior transpetrosal approach–induced liquorrhea, we developed a method involving the double application of abdominal adipose tissue in the subdural and epidural spaces. Materials and Methods: The method was applied to 8 patients who underwent surgery under a posterior transpetrosal approach: 4 with petroclival meningioma and 1 each with tentorial meningioma, jugular foramen neurinoma, trigeminal neurinoma, and metastatic brain tumor. The combined transpetrosal approach was used for 6 patients and the combination with the lateral suboccipital approach was used for the other 2 patients. After tumor resection, the divided dura mater of the presigmoid space was closed as follows: first, a fat mass excised from the abdominal region was divided into 2 parts, and several excisions were made in each part to flatten them. The exposed brain surface was covered with the flattened fat, and the fat margin was circumferentially inserted under the dura mater. The division was then closed by suturing the dural stumps at several sites, loading tension to some extent. Finally, the other part of the adipose tissue was spread in the epidural space in the dural-defective region for double closure inside and outside the dura mater. Results: Liquorrhea was prevented in all patients. Conclusions: It was concluded that this method is useful to prevent postoperative liquorrhea induced by a posterior transpetrosal approach.

A three-dimensional quantitative measurement related to sigmoid sinus by using multi-slices spiral CT

To provide a valuable imaging anatomic method for operation of the posterior transpetrosal approach and accurate positioning among relative structures in order to reduce the incidence of surgical complications. The clinical information of 119 adult cases (238 sides) was analyzed. All the cases underwent 16 layer helix CT scanning and three-dimensional image reconstruction of skull base without a skull base disease. Axial and coronal images were reconstructed using multiplanar reconstruction technique of ADW 4.2 workstation, and the anatomic objective structure were displayed by rotating imaging slices. The data were analyzed in statistically and compared with the published cadaver data. Quantitative measurement of anatomic structure was shown as below: The distance of width of sigmoid sinus was (11.14 + or - 2.13) mm, the distance of depth of sigmoid sinus was (6.04 + or - 1.67) mm; the distance from the lateral wall of sigmoid sinus to the surface of mastoid process was (9.74 + or - 2.95) mm; the distance from the anterior wall of sigmoid sinus to the posterior wall of external auditory meatus was (12.98 + or - 2.71) mm; the distance from the most posterior portion of the posterior semicircular canal to the anterior wall of sigmoid sinus was (9.87 + or - 2.60) mm; the distance from the most posterior portion of the posterior semicircular canal to the posterior pyramidal wall was (3.18 + or - 1.30) mm; the distance from the posterior extremity of long axis of the lateral semicircular canal to the anterior wall of sigmoid sinus was (13.17 + or - 2.59) mm; the distance from the posterior extremity of long axis of the lateral semicircular canal to the posterior pyramidal wall was (5.46 + or - 1.38) mm; the vertical distance from the lateral semicircular canal to the jugular bulb was (6.69 + or - 3.08) mm; and the distance from the vertical portion of facial nerve to the jugular bulb was (5.32 + or - 2.13) mm. Statistically, there were no significant differences between imaging quantitative measurement and published cadaver data. However, the measurement result, included the distance from the lateral wall of sigmoid sinus to the surface of mastoid process and the distance from the lateral semicircular canal to the jugular bulb as well as the distance from the vertical portion of facial nerve to the jugular bulb, were found a positively correlated to the distance from the anterior wall of sigmoid sinus to the posterior wall of external auditory meatus (r value was 0.284, 0.145, 0.208, respectively, all P < 0.05). The result of three-dimensional quantitative measurement by using multiplanar reconstruction technique of 16 layer spiral CT could represent a real distance of anatomic structures. The reconstruction of spiral CT images could display a anatomic feature of temporal bone accurately, and it may provide a valuable method for surgical approach and accurate positioning of relative structure in operation. As the location of sigmoid sinus moving forward, the lateral shift of it may occur more easily and the jugular bulb become closer to the vertical portion of facial nerve, while the extension of anterior location in sigmoid sinus should be a positively correlated to the height of jugular bulb.

Surgical and Histological Observations of Trochlear Neurinoma -Case Report-

A 47-year-old woman presented with an extremely rare case of trochlear nerve neurinoma manifesting as left hemiparesis. Magnetic resonance imaging demonstrated a cystic tumor, 4 cm in diameter, in the right ambient and cerebellopontine cisterns, compressing the midbrain and upper pons. The preoperative diagnosis was trigeminal neurinoma. However, the tumor was identified arising from the trochlear nerve, and was totally removed via the posterior transpetrosal approach. The histological diagnosis was neurinoma. The patient's hemiparesis improved postoperatively. Preoperative diagnosis of trochlear neurinoma must distinguish the neurological presentations of trochlear and trigeminal neurinomas and to analyze the microanatomy of the tumor and skull base structures on neuroimaging.

POSTERIOR TRANSPETROSAL APPROACH

We describe our surgical posterior transpetrosal technique, particularly the transcrusal variant for lesions involving the upper and middle clivus, petroclival regions, and lesions that involve both the posterior and middle fossae. An outline of the posterior transpetrosal technique involved, particularly the transcrusal variant, is described. Important superficial landmarks are identified, and a radical mastoidectomy is performed. The antrum is identified and entered, and, upon completion of the mastoidectomy and when Trautman's triangle is defined, the temporal and suboccipital craniotomies are completed. After bone flap elevation, dura opening, and incision along the middle fossa dura, the superior petrosal sinus is ligated and cut. Tentorium cut completion is at the incisura posterior to the trochlear nerve. Watertight dural closure and standard flap replacement and skin closure complete the technique. Clival exposure and the degree of temporal bone resection increase. Operative freedom also increases with increased temporal bone resection, especially when going from the retrolabyrinthine to transcrusal variants. Little is gained in terms of operative freedom and exposure of the clivus with resection of additional temporal bone beyond that of the transcrusal variant, and resection carries the cost of increasing morbidity, especially with respect to VIIth and VIIIth nerve function. The posterior transpetrosal approach and the transcrusal variant provide a lateral operative corridor to lesions of the upper and middle clivus. The transcrusal variant provides increased exposure and operative freedom similar to that provided by the transcochlear approach while minimizing cranial nerve morbidity.

Transpetrosal approaches to the posterior fossa

Resection of the petrous temporal bone to various degrees provides different levels of access to lesions of the posterior fossa. Although their nomenclature can be confusing, the numerous variants of the transpetrosal approaches can be classified broadly into anterior and posterior groups. The posterior transpetrosal approaches include the retrolabyrinthine, translabyrinthine, and transcochlear, whereas the ones in the anterior group are extensions of the basic middle fossa approach. Both the anterior and posterior approaches have the potential of exposing the cerebellopontine angle and the petroclival region. The posterior approaches are based on the standard mastoidectomy and involve resection of the petrous bone to various degrees. This results in progressively increased exposure anteriorly, but comes at the expense of hearing in the translabyrinthine approach and of hearing and facial strength in the transcochlear approach. In contrast, the middle fossa approaches spare the lateral petrous bone and involve resection of the medial petrous bone to various degrees. All of the middle fossa approaches are designed to preserve hearing. Extensions of the middle fossa approaches involve resection of bone within the Kawase rhomboid and division of the tentorium to provide exposure of the posterior fossa.

Resection of arteriovenous malformation in the middle cerebellar peduncle by a posterior transpetrosal approach: illustration of a case and correlative microsurgical anatomy

Background Lesions located in the posterolateral brain stem, particularly the middle cerebellar peduncle, have presented surgeons with a challenge associated with significant morbidity. Methods We present a case of a 20-year-old woman who had a hematoma in the right middle cerebellar peduncle with a ventricular rupture. Angiography revealed an arteriovenous malformation (AVM) located in the same portion, extending from the lateral surface near the entry zone of the trigeminal nerve to the paraventricular area of the fourth ventricle, which was completely resected through a posterior transpetrosal approach. We also describe the microsurgical anatomy of this region in a cadaveric specimen, presenting the anatomic landscape at the target when approaching through this route. Results The patient's postoperative course was uneventful and her neurologic deficits progressively but gradually improved. When a lesion exists at or close to the surface of the middle cerebellar peduncle, the best approach, in our estimation, is a transpetrosal approach because the lesion can be approached perpendicularly with a short working distance, various angles for dissection are available, and minimal retraction of the temporal lobe and cerebellum is required. Conclusion An AVM embedded in the middle cerebellar peduncle can be successfully resected using a posterior transpetrosal approach, though we concede this approach is slightly labor-intensive and time-consuming.

Surgical removal of retrochiasmatic craniopharyngiomas with transpetrosal approach

Although there is general agreement that surgery is the preferred treatment for craniopharyngiomas, the extent of resection and optimal approach are still debated. Since 1973 our institute has used the transpetrosal approach to remove cerebellopontine angle and clivus tumors. We also prefer this approach for the removal of retrochiasmatic craniopharyngiomas. The principal advantage of the transpetrosal approach is that it allows the hypothalamus, the wall of the third ventricle, and the inferior surface of the optic chiasm to be visualized directly during surgery. Between 1980 and 2002, 28 patients with retrochiasmatic craniopharyngiomas underwent a combined anterior and posterior transpetrosal approach with a partial labyrinthectomy. The mean follow-up was 13.6 years (range, 0.8–23 years). Total removal of the tumor was confirmed in 25 (89%) cases. Preoperatively, patients had a visual disturbance, which improved in 10 cases, worsened 3 cases, and was unchanged in 1 case. This approach is useful for the aggressive surgical treatment of retrochiasmatic craniopharyngiomas.