Combined subtemporal and retrosigmoid keyhole approach for extensive petroclival meningioma surgery: report of experience with 7 cases.

OBJECTIVE: Resection of petroclival meningiomas offers great challenges to the neurosurgeons. Our experience of 7 cases using a combined subtemporal and retrosigmoid keyhole approach surgery was evaluated for the treatment of extensive petroclival meningiomas. METHODS: From July 2002 to July 2005, resections of 7 petroclival meningiomas, which involved both supra- and infratentorial regions, were performed via a combined subtemporal and retrosigmoid keyhole approach. The extent of tumor resection was evaluated by MRI 3 months after surgery, and postoperative complications were investigated. RESULTS: The maximum diameter of the tumors ranged from 3.4 to 6.0 cm (mean: 4.4 cm). Gross total resection (GTR) was achieved in 3 cases, giving a GTR rate of 43%. Subtotal resection (STR) was carried out in 4 cases. Neurological status remained intact in one case, while others presented with cranial nerve deficits (VII, VI, V, III and lower CN). No death was reported in the cases during the postoperative period. CONCLUSION: The combined keyhole approach is suitable for the treatment of extensive petroclival meningiomas. It provides easy and quick access to the supra- and infratentorial juxtaclival region without any petrous bone drilling. Complications related to the approach can be minimized.     

Selection of surgical approaches based on semi-quantifying the skull-base invasion by petroclival meningiomas: a review of 66 cases

Background

Petroclival meningiomas are still challenging for neurosurgeons. In the present study, we reviewed 66 petroclival meningiomas that underwent craniotomy to assess the surgical approaches for petroclival meningiomas based on semi-quantifying tumor extension to skull base and to evaluate the outcomes.

Methods

According to invasion characteristics, skull base related to petroclival meningiomas was semi-quantitatively divided into five regions: upper, middle, and lower petroclival regions (region A, B, and C, respectively), cerebellopontine angle region (region D), and parasellar and cavernous sinus region (region E). Appropriate surgical approaches were adopted for petroclival meningiomas with varying degrees of invasion, including the subtemporal (11/66), retrosigmoid (15/66), presigmoid (32/66), combined retrosigmoid and far-lateral (2/66), supra-infratentorial (4/66), and extended middle cranial fossa (2/66) approaches.

Results

The results showed that involvement of region A, B, and C was in 64, 50, and eight patients, respectively. Invasion to region D and E occurred in 13 and 39 cases, respectively. The ratio of single region involvement was only 7.6 %, whereas most petroclival meningiomas tended to invade more regions (39.4 % for two, 37.9 % for three, 12.1 % for four, and 3.0 % for five regions, respectively). Gross total resection was achieved in 29 cases (43.9 %), near total resection in 27 cases (40.9 %), and subtotal resection in ten cases (15.2 %). After a mean follow-up period of 32.21 months, obvious cranial nerve deficits existed in seven patients, and recurrence occurred in eight patients.

Conclusions

We introduced a simple and practicable method for classification of petroclival meningiomas, which could semi-quantify tumor invasion and help to select surgical approaches. With careful preoperative evaluation, a cautiously selected approach would improve the prognosis.     

Combined Pre- and Retrosigmoid Approach for Petroclival Meningiomas with the Aid of a Rotatable Head Frame: Peri-Auricular Three-Quarter Twist-Rotation Approach: Technical Note

We used the combined subtemporal presigmoid and suboccipital retrosigmoid multidirectional approach with the aid of a rotatable head frame (periauricular three-quarter twist-rotation approach) in 20 cases of petroclival meningiomas. Patients were placed in the lateral decubitus (park-bench) position. The head is twisted, rotated, and positioned 30 degrees face down in the Sugita rotatable head frame. By rotating this head frame, a 30- to 60-degree face-down position can be obtained when the suboccipital retrosigmoid route is used. Alternatively, the straight lateral or slightly brow-up position is obtained when the subtemporal presigmoid route is used. This twist-rotation approach provides multiple trajectories through the petroclival region with minimal drilling of the petrous bone, fatigue of the surgeon, and retraction of the brain.     

Conventional posterior fossa approach for surgery on petroclival meningiomas: a report on an experience with 28 cases

BACKGROUND: This is a report of our experience with 28 cases of select petroclival meningiomas operated by a posterior fossa route encompassing the lateral supracerebellar-infratentorial and retrosigmoid avenues. METHODS: Twenty-eight cases of petroclival meningiomas treated during the period 1991 to 2002 by conventional posterior cranial fossa route are analyzed. The average length of follow-up is 48 months. RESULTS: The maximum diameter of the tumors ranged from 1.8 to 6.8 cm (mean, 4.0 cm). Five tumors extended up to or beyond the contralateral petroclival junction. Basilar artery was at least partially encased in 9 cases. Gross total tumor resection was achieved in 21 cases and a partial tumor resection was achieved in the remaining 7 cases. Two patients died in the postoperative phase. CONCLUSIONS: Conventional posterior cranial fossa surgery can be suitable for a select group of petroclival meningioma. Apart from other advantages, it provides easy and quick exposure of the tumor without any petrous bone drilling. It also provides a direct and early exposure of the tumor-cranial nerve-brainstem interface facilitating the dissection. The lateral and inferior tumor extensions in relationship to the clivus can be more easily accessed. The site of attachment of the tumor to the dura overlying the posterior face of the petrous apex can be seen directly.     

Retrosigmoid intradural suprameatal approach to Meckel's cave and the middle fossa: surgical technique and outcome

OBJECT: The goal of this study was to determine whether some petroclival tumors can be safely and efficiently treated using a modified retrosigmoid petrosal approach that is called the retrosigmoid intradural suprameatal approach (RISA). METHODS: The RISA was introduced in 1983, and since that time 12 patients harboring petroclival meningiomas have been treated using this technique. The RISA includes a retrosigmoid craniotomy and drilling of the suprameatus petrous bone, which is located above and anterior to the internal auditory meatus, thus providing access to Meckel's cave and the middle fossa. Radical tumor resection (Simpson Grade I or II) was achieved in nine (75%) of the 12 patients. Two patients underwent subtotal resection (Simpson Grade III). and one patient underwent complete resection of tumor at the posterior fossa with subtotal resection at the middle fossa. There were no deaths or severe complications in this series; all patients did well postoperatively, being independent at the time of their last follow-up examinations (mean 5.6 years). Neurological deficits included facial paresis in one patient and worsening of hearing in two patients. CONCLUSIONS: The approach described here is a useful modification of the retrosigmoid approach, which allows resection of large petroclival tumors without the need for supratentorial craniotomies. Although technically meticulous, this approach is not time-consuming; it is safe and can produce good results. This is the first report on the use of this approach for petroclival meningiomas.     

Value of retrolabyrinthine approach for surgical resection of meningiomas inserted around the lateral sinus between the transverse and sigmoid parts

PURPOSE: To describe the retrolabyrinthine approach for the resection of 9 meningiomas inserted around the lateral sinus between the transverse and sigmoid parts, to discuss the value of this approach compared to the retrosigmoid approach for resection of meningioma in this localization and to review the literature. METHODS: Retrospective study. Between 1988 and 2002, 9 patients (8 female, mean age 50 years) underwent surgery via the retrolabyrinthine approach for resection of meningiomas inserted around the lateral sinus between the transverse and sigmoid parts. RESULTS: Resection was total (8 Simpson I and 1 Simpson II) in all patients. In the early postoperative course, one patient was treated for meningitidis with an LCR leak and one patient present a temporary paresis of the vagus nerve. Mean follow-up was 5 years (6 months-10 years). All patients continued their pre-treatment occupation after surgery. No recurrence was observed. CONCLUSION: Two approaches can be used for resection of meningiomas in this localization. The retrosigmoid approach is a common neurosurgical approach exposure of the cerobellopontine angle. It is practised by most neurosurgeons. Via this approach, the cerebellar lobe must be pushed back so the arteries feeding the tumor are in the operative field at the end of the procedure. For numerous authors the operative field is too narrow. On the other hand, the retrolabyrinthine approach described in 1972 by Hitselberger and Pulec allows exposure of feeding arteries during the first steps of operation, an easier resection of meningioma insertion and better control of the lateral sinus. This approach can be enlarged to the retrosigmoid or the subtemporal anatomic region.     

岩斜区肿瘤手术入路选择的探讨

目的 探讨岩斜区肿瘤的手术入路选择。对53例岩斜区肿瘤患者的手术治疗进行分析。方法患者采用颞底经天幕入路11例,枕下乙状窦后入路12例;（颧弓或眶颧）翼点入路12例;乙状窦前入路2例;颞底、乙状窦后幕上下联合入路7例;颞下前岩骨硬膜外入路7例;扩大的前颅底硬膜外入路2例。结果32例（61％）患者肿瘤全切除,9例（17％）次全切除,12例（22％）大部切除。术后新发生颅神经功能障碍16例（30％）,死亡2例（4％）。结论枕下乙状窦后入路、颞底经天幕入路等岩斜区手术入路均可以在熟练的显微操作技术及神经导航、神经内镜下进行。主体生长于硬膜外的岩斜肿瘤适合于采用硬膜外入路手术切除。幕上下联合入路对巨大岩斜区肿瘤是理想的手术入路。     

Long-term follow-up of meningiomas of the cavernous sinus after surgical treatment alone

OBJECT: The authors report on the long-term outcome in 100 consecutive patients with meningiomas arising from the cavernous sinus (CS) with compressive extension outside the CS. The treatment in all cases was surgery alone without adjuvant radiosurgery or radiotherapy. The aim of this study was to evaluate the percentage of patients in whom surgery alone was able to produce long-term tumor control. METHODS: All 100 patients harbored meningiomas with supra- and/or laterocavernous extension, and 27 had petroclival extension. Surgery was performed via frontopterionotemporal craniotomy associated with orbital and/or zygomatic osteotomy in 97 patients. Proximal control of the internal carotid artery at the foramen lacerum was undertaken in 65 patients; the paraclinoid carotid segment was exposed extradurally at the space made by the anterior clinoidectomy in 81 patients. For the petroclival tumor extension, a second-stage surgery was performed via a presigmoid-retrolabyrinthine or retrosigmoid approach in 13 and 14 patients, respectively. RESULTS: The mortality rate was 5% and two patients had severe hemiplegic or aphasic sequelae. The creation or aggravation of disorders in vision, ocular motility, or trigeminal function occurred in 19, 29, and 24% of patients respectively, with a significantly higher rate of complications when resection was performed inside the CS (p < 0.05). Gross-total removal of both the extra- and intracavernous portions was achieved in 12 patients (Group 1), removal of the extracavernous portions with only a partial resection of the intracavernous portion in 28 patients (Group 2), and removal only of the extracavernous portions was performed in 60 patients (Group 3). The follow-up period ranged from 3 to 20 years (mean 8.3 years). There was no tumor recurrence in Group 1. In the 83 surviving patients in Groups 2 and 3 combined, the tumor remnant did not regrow in 72 patients (86.7%); regrowth was noted in 11 (13.3%). CONCLUSIONS: The results suggest that there is no significant oncological benefit in performing surgery within the CS. Because entering the CS entails a significantly higher risk of complications, radiosurgical treatment should be reserved for remnants with secondary growth and clinical manifestations.     

Lateral Suboccipital Retrosigmoid Approach with Tentorial Incision for Petroclival Meningiomas: Technical Note

Introduction The resection of petroclival meningiomas presents great neurosurgical challenges. Although multiple surgical approaches have been developed, the retrosigmoid route tends to be used to address tumors that are predominantly located in the posterior fossa. Our modification of the lateral suboccipital retrosigmoid approach with the placement of a tentorial incision yields good visualization of the supratentorial part of the tumor around the midbrain. Methods We treated four patients, one with primary and three with recurrent petroclival meningioma, by our modified approach. After lateral suboccipital craniotomy, the infratentorial part of the tumor was removed after detaching it from the tentorial surface. The cerebellar tentorium was then carefully incised from the supracerebellar angle, taking care not to damage the superior cerebellar artery and trochlear nerve. Results The operative field surrounding the midbrain was widened by this procedure, and safe dissection of the tumor from the brainstem and other neurovascular structures was performed with direct observation of the interface. Conclusions Our approach is a useful modification of the retrosigmoid approach to petroclival meningiomas. It facilitates the safe resection of the supratentorial part of the tumor in the ambient cistern behind the tentorium.     

Long term surgical results of 154 petroclival meningiomas: A retrospective multicenter study

BackgroundOutcomes of petroclival meningiomas (PCM) (morbidity, permanent cranial nerves deficit, tumor removal and recurrence) are inconsistent in the literature, making it a challenge to predict surgical morbidity.MethodsA multicenter study of patients with PCMs larger than 2.5 cm between 1984 and 2017 was conducted. The authors retrospectively reviewed the patients’ medical records, imaging studies and pathology reports to analyze presentation, surgical approach, neurological outcomes, complications, recurrence rates and predictive factors.ResultsThere were 154 patients. The follow-up was 76.8 months on average (range 8–380 months). Gross total resection (GTR) was achieved in 40 (26.0%) patients, subtotal resection (STR) in 101 (65.6%), and partial resection in 13 (8.3%). Six (2.6%) perioperative deaths occurred. The 5-year, 10-year and 15-year progression-free survival (PFS) of GTR and STR with radiation therapy (RT) was similar (100%, 90% and 75%). PFS of STR without adjuvant radiation was associated with progression in 71%, 51% and 31%, respectively. Anterior petrosectomy and combined petrosectomy were associated with higher postoperative CN V and CN VI deficits compared to the retrosigmoid approach. The latter had a significantly higher risk of CN VII, CN VIII and LCN deficit. Temporal lobe dysfunction (seizure and aphasia) were significantly associated with the anterior petrosectomy approach.ConclusionsOur study shows that optimal subtotal resection of PCMs associated with postoperative RT or stereotactic radiosurgery results in long-term tumor control to equivalent radical surgery. Case selection and appropriate intraoperative judgement are required to reduce the morbidity.     

Combined petrosal approach to petroclival meningiomas

OBJECTIVE: To study the use and advantages of combining the posterior petrosal approach with the anterior petrosal approach to petroclival meningiomas. METHODS: Seven cases of petroclival meningiomas operated on via the combined petrosal approach were retrospectively analyzed. The basis on which this approach was selected was assessed, as were its benefits and risks. RESULTS: Gross total resection was achieved in five of the seven patients. No mortality or decrease in Karnofsky performance score was observed at the time of the last follow-up examination. Six of the seven patients had serviceable hearing before the operation. Only one patient lost hearing after the operation, and this hearing loss occurred in only one ear. Before the operation, six patients were House-Brackmann facial nerve function Grade I, and one patient was Grade II to III. At the last follow-up examination, facial nerve function was Grade I in five patients, Grade II in one patient, and Grade V in one patient. Tumors in all patients involved the cavernous sinus, Meckel's cave, petroclival junction, and middle clivus. All patients possessed a large posterior fossa component of tumor measuring an average of 3.6 x 3.5 x 4.2 cm. In four patients, the tumor was attached for the entire width of the clivus to the contralateral petroclival junction. Four patients displayed central brainstem compression. Four patients displayed bony changes at the petrous apex. All patients displayed total or partial encasement of the vertebrobasilar artery and its major branches. CONCLUSION: The combined petrosal approach should be considered for patients who have a large petroclival meningioma and serviceable hearing. This approach enhances petroclival exposure and the degree of tumor resection, especially in the area of the petroclival junction, middle clivus, apical petrous bone, posterior cavernous sinus, and Meckel's cave. The combined petrosal approach also allows better visualization of the contralateral side and the ventral brainstem, which facilitates safe dissection of the tumor from the brainstem, the basilar artery, and the perforators. If a patient has an early draining bridging vein to the tentorial sinus (before it reaches the transverse-sigmoid junction) or a prominent sigmoid sinus and jugular bulb, the combined petrosal approach provides significant working space.     

Experience with 36 surgical cases of petroclival meningiomas

Summary Thirty-six patients with petroclival meningiomas underwent surgery between 1978 and 1990. The tumours accounted for 13% of a total of 284 skull base meningiomas operated upon during the same time period. The most frequent neurological signs related to cranial nerve deficits, mainly of the 8th, 5th, and 7th nerves respectively. The approaches to the petroclival region were: retromastoid, pterional, subtemporal, and combined retromastoid-subtemporal. In 12 patients we used a modification of the retromastoid-subtemporal approach with preservation of the sigmoid and transverse sinus (presigmoid approach). Total tumour removal was achieved in 27 cases (75%). There was no postoperative death, and in 83% of cases no severe morbidity. With careful pre-operative evaluation, improved operative approaches and microsurgical techniques the treatment of petroclival meningiomas has been considerably improved.Presented at the EANS-Wintermeeting on High Risk Neurosurgery, Budapest, February 20–23, 1991.     

神经内镜辅助眶上锁孔入路治疗巨大嗅沟脑膜瘤

目的探讨神经内镜辅助眶上锁孔入路治疗巨大嗅沟脑膜瘤的手术效果及手术技巧。方法采用内镜辅助、眶上锁孔入路（显微手术）治疗12例巨大（≥7cm）嗅沟脑膜瘤。结果肿瘤全切除9例（SimpsonⅠ级切除5例，Ⅱ级切除4例），次全切除（SimpsonⅢ级切除）3例。无手术死亡。10例随访3个月～2年，平均14个月。9例恢复正常生活，1例生活能自理。NRI随访9例，肿瘤无复发。结论利用神经内镜辅助及显微外科技术，采用眶上锁孔入路、对肿瘤进行分块切除治疗巨大嗅沟脑膜瘤，手术创伤小，疗效满意。     

幕上下经岩骨乙状窦前入路切除巨大岩斜部肿瘤

目的 探讨幕上下经岩骨乙状窦前入路切除岩斜部肿瘤手术的技巧及并发症。方法 取颞枕游离骨瓣,分别于迷路前后将乳突及岩骨根部大部切除,但保留骨性半规管、耳蜗及鼓室的完整性;结扎并切断岩上窦,自乙状窦前方抵达岩斜部。结果 ４１例肿瘤包括脑膜瘤２０例,表皮样囊肿２０例,神经鞘瘤１例。手术全切肿瘤３４例,近全切除６例,大部切除１例。术后一过性失语１０例,脑水肿６例。脑干梗塞２例,第Ⅲ、Ⅵ、Ⅶ及后组颅神经损伤     

Combined extradural subtemporal and anterior transpetrosal approach to tumors located in the interpeduncular fossa and the upper clivus

Background

Central skull base lesions in the interpeduncular fossa and the upper clival regions can be challenging to access because of their location anterior to the brainstem. We have modified the anterior transpetrosal approach by combination with the extradural subtemporal route to increase the surgical corridor.

Methods

Thirty-seven patients underwent surgical treatment via the anterior transpetrosal approach from 2002 to 2012. The combined surgical approach was primarily applied when the tumors arose from the upper clival portion and extended to the interpeduncular fossa. The combined approach was used in seven of these patients, comprising four patients with petroclival meningiomas, one patient with sphenoclival meningiomas, one patient with trigeminal schwannoma, and one patient with an epidermoid cyst extending from the interpeduncular fossa to the prepontine cistern.

Results

The combined approach permitted excellent visualization of the interpeduncular fossa in addition to the upper clivus and the lateral aspect of the brain stem. Mobilization of the temporal lobe by the entire epidural dissection of the lateral wall of the cavernous sinus facilitates access via the subtemporal route. The transient symptom of the temporal lobe in the dominant site may be the only drawback for this combined approach, although it may disappear immediately after the surgery.

Conclusion

The present approach combines Dolenc’s approach and Kawase’s approach, providing a wide exposure to lesions of the interpeduncular fossa and the clivus.     

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.     

Surgical removal of small petroclival meningiomas

Summary Treatment of large petroclival meningiomas causing brain stem compression is surgical removal followed by radiotherapy or radiosurgery if the lesion was partially resected. The management of small petroclival meningiomas is, however, controversial. Clinical observation, radiosurgery and surgical removal are the options of treatment. The natural history of these tumours is not well known. Published series of patients treated with radiosurgery are not comparable with surgical series because the latter also includes large size tumours. In this paper we present a series of 18 patients with small petroclival meningiomas (diameter ≤ 2.8 cm) treated with radical surgical removal. Total resection (Simpson’s Grade 1) [43] was possible with minimal morbidity and no mortality. Background. We present a series of small petroclival meningiomas (SPM) treated by radical surgical removal and compare the outcome with other management modalities proposed for these lesions. Methods. Eighteen patients with SPM were surgically treated at our department of neurological surgery. The tumours were classified as small when they had a diameter < 3.0 cm. Headaches (n = 12), diplopia (n = 8), facial hypoaesthesia (n = 3) and tinnitus (n = 6) were the most frequent symptoms at presentation. The approaches used were retrosigmoid (n = 14), fronto-orbito-zygomatic (n = 3) and presigmoid (n = 1). The post-operative follow-up ranged from 1 to 110 months (mean 41.8 months). Findings. Radical tumour resection (Simpson’s Grades 1 and 2) was achieved in all patients. There was no major morbidity or mortality related to the surgical procedure. Transient abducent nerve palsy was the only post-operative complication. The pre-operative cranial nerves deficits improved after surgery. Only one patient had persistent diplopia postoperatively. Conclusion. Radical surgical removal of SPM is possible with minimal morbidity and may cure the patient. The effectiveness and outcome of surgery for small petroclival meningiomas should be compared with series treated by radiosurgery. Correspondence: Ricardo Ramina, R. Goncalves Dias 713, 80240340 Curitiba, Brazil.     

The combined supra-infratentorial pre-sigmoid sinus avenue to the petro-clival region. surgical technique and clinical applications

Summary Nine patients with tumours located at the petro-clival region were operated upon from June 1985 to June 1988 using a combined supra- and infratentorial approach anterior to the sigmoid sinus. Two patients had petroclival meningiomas. 4 foramen jugulare neurinomas and 3 glomus jugulare tumours. There was no mortality. Total tumour removal was accomplished in all the patients. All patients remained independent postoperatively. The surgical approach used involves a temporal craniotomy, a suboccipital craniectomy, an extensive mastoidectomy and petrous pyramid drilling without entering the bony labyrinth, the middle ear or the Fallopian canal. The dura is incised supratentorially over the posterior temporal lobe and infratentorially in front of the sigmoid sinus. The temporal lobe is retracted superiorly and the cerebellum and the sigmoid sinus medially. This approach makes use of a very short distance to the petroclival area, offers a multiangled exposure, preserves the dural sinuses, does not iatrogenically impair hearing and minimizes temporal lobe retraction. This exposure is particularly useful in large tumours.     

Subtemporal Transtentorial Petrosalapex Approach for Giant Petroclival Meningiomas: Analyzation and Evaluation of the Clinical Application

With the advent of microsurgery and surgical techniques, along with the improvement in neuroimaging techniques and the microanatomy in cadaver study, improvement in terms of surgical morbidity and mortality has been remarkable; however, controversy still exists regarding the optimal surgical strategies for giant petroclival meningiomas (GPMs). We report a study of clinical and radiological features as well as the surgical findings and outcomes for patients with GPM treated at our institution over the past 6 years. During a 6-year period (April 2004 to March 2010), 16 patients with GPM underwent surgery by subtemporal transtentorial petrosal apex approach during which electrophysiological monitoring of cranial nerves and brainstem function were reviewed. There were nine females and seven males with a mean age of 56.9 years (range from 32 to 78 years). The most frequent clinical manifestations were headache (93.7%) and dizziness (93.7%). Regions and directions of tumor extension include clivus, parasellar, and cavernous sinus, as well as compression of brainstem, and so on. The trochlear nerve was totally wrapped in nine cases (56.2%). The postoperative Karnofsky Performance Scale (KPS) score was 76.3 ± 13.1. Mean maximum diameter of the tumors on magnetic resonance imaging was 5.23 cm (range, 4.5 to 6.2 cm). Subtemporal transtentorial petrosalapex approach was performed in all 16 cases. Gross total resection was achieved in 14 cases (87.5%) and subtotal resection in 2 cases (12.5%) with no resultant mortality. Follow-up data were available for all 16 patients, with a mean follow-up period of 28.8 months (range from 4 to 69 months), of which 11 (68.75%) lived a normal life (KPS, 80–100). Our suggestion is that GPM could be completely resected by subtemporal transtentorial petrosalapex approach. The surgical strategy of GPM should be focused on survival and postoperative quality of life. Microneurosurgical technique plays a key role in tumor resection and preservation of nerve function. Intraoperative electrophysiological monitoring also contributes dramatically to the preservation of the nerve function. Complete resection of the tumor should be attempted at the first operation. Any remnant is treated by radiosurgery.     

Anatomical variation of superior petrosal vein and its management during surgery for cerebellopontine angle meningiomas

No systematic study is yet available that focuses on the surgical anatomy of the superior petrosal vein and its significance during surgery for cerebellopontine angle meningiomas. The aim of the present study was to examine the variation of the superior petrosal vein via the retrosigmoid suboccipital approach in relation to the tumor attachment of cerebellopontine angle meningiomas as well as postoperative complications related to venous occlusion. Forty-three patients with cerebellopontine angle meningiomas were analyzed retrospectively. Based on the operative findings, the tumors were classified into four subtypes: the petroclival type, tentorial type, anterior petrous type, and posterior petrous type. According to a previous anatomical report, the superior petrosal veins were divided into three groups: Type I which emptied into the superior petrosal sinus above and lateral to the internal acoustic meatus, Type II which emptied between the lateral limit of the trigeminal nerve at Meckel’s cave and the medial limit of the facial nerve at the internal acoustic meatus, and Type III which emptied into the superior petrosal sinus above and medial to Meckel’s cave. In both the petroclival and anterior petrous types, the most common vein was Type III which is the ideal vein for a retrosigmoid approach. In contrast, the Type II vein which is at high risk of being sacrificed during a suprameatal approach procedure was most frequent in posterior petrous type, in which the superior petrosal vein was not largely an obstacle. Intraoperative sacrificing of veins was associated with a significantly higher rate of venous-related phenomena, while venous complications occurred even in cases where the superior petrosal vein was absent or compressed by the tumor. The variation in the superior petrosal vein appeared to differ among the tumor attachment subtypes, which could permit a satisfactory surgical exposure without dividing the superior petrosal vein. In cases where the superior petrosal vein was previously occluded, other bridging veins could correspond with implications for the crucial venous drainage system, and should thus be identified and protected whenever possible.