The middle fossa transpetrous approach: experience with 13 cases

Surgical access to lesions of the temporal bone anterior to the internal auditory canal and medial to the petrous carotid artery has concerned surgeons for nearly a century. A variety of approaches have been developed to gain access to this region. We report our experience with the middle fossa transpetrous approach for the treatment of a variety of petroclival and/or prepontine lesions. Tentorial transection and the retrolabyrinthine approach to extend this technique is also discussed. In properly selected cases, the middle fossa transpetrous approach is successful in maintaining hearing, labyrinthine and facial function without compromising surgical exposure.     

Surgical resection of large and giant petroclival meningiomas via a modified anterior transpetrous approach

The authors describe a modified anterior transpetrous approach (ATPA) for the surgical resection of 21 cases of petroclival meningiomas (PCMs). Briefly, a curved periauricular skin incision was used. The cerebellar tentorium and the dura on the petrous apex were coagulated and incised to expose the petrous apex bone fully. The drilling of the petrous apex bone was performed subdurally and began internally from the trigeminal impression, not exceeding 1.5 cm laterally, not exceeding 6 mm from the posterior edge of the petrous ridge, and not exceeding 8 mm in depth from the surface of the petrous bone. The tumors were removed totally in 12 (57.1 %) cases, subtotally in 8 (38.1 %) cases, and partially in 1 (4.8 %) case. The transient neurological deficit includes mild oculomotor nerve palsy in three cases, abducens nerve palsy in six cases, language disorder in three cases, and mild hemiplegia in two cases. Facial numbness became worse postoperatively in six patients, and only two patients improved at 6 months after surgery. No death occurred in this series. The modified ATPA is an efficient treatment alterative for large or giant PCMs located at the medial and superior internal acoustic meatus with relatively low risk of complications.     

Petrosal approach for petroclival meningiomas

Thirteen patients harboring large petroclival meningiomas are reported. The evolution of the petrosal approach is discussed, and modifications for improvement in surgical technique are described. There was no mortality in this series, and total removal was achieved in all but two patients. Morbidity included cranial nerve deficit, pulmonary embolism, and hemiparesis.     

岩斜部脑膜瘤的微侵袭治疗

目的探讨微侵袭神经外科技术在岩斜脑膜瘤治疗中的应用。方法采用锁孔技术治疗14例岩斜部脑膜瘤。累及上中斜坡8例，广基或宽基累及上中下斜坡5例，累及中下斜坡1例其中6例同时扩展至鞍旁或海绵窦内，采用枕下乙状窦后锁孔入路6例，颞下锁孔入路2例，幕上下联合入路6例。结果全切除肿瘤8例，次全切除4例，大部切除2例(均为术后复发患者)。术后神经功能完好或未见新增脑神经损伤8例，术后出现轻度面瘫4例，外展功能障碍3例，动眼神经麻痹2例，后组脑神经功能影响1例，均未发生术后脑脊液漏和切口感染经11～19个月随访，轻度面瘫和动眼神经麻痹均有明显改善，但外展功能障碍恢复缓慢。结论针对岩斜部脑膜瘤累及范围，采用单独／联合采用颞下锁孔入路和枕下乙状窦后锁孔入路可有效切除肿瘤，并可减少手术创伤，缩短手术和患者康复时间，减少术后并发症。联合运用微侵袭技术(锁孔入路联合)，术中显微技术与术后放射外科治疗等是今后岩斜部脑膜瘤的治疗方向。     

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.     

Presigmoid sinus approach to petroclival meningiomas

Between August 1987 and May 1989 five patients with petroclival meningiomas were operated on at the Neurosurgical Clinic of the Krankenhaus Nordstadt. Hannover, Germany, using an original combined supra- and infratentorial presigmoid sinus approach. There were two men and three women, ranging in age from 34 to 61 years (mean, 48 years; median, 46 years). Follow-up ranged between 1 and 22 months. There was no death. Postoperatively, two patients had no useful hearing, one had a permanent facial palsy (the facial nerve had to be sacrificed intraoperatively due to its involvement with tumor), one had a permanent abducens palsy (the VI nerve was involved with tumor and had to be cut). Temporary lower (IX to XII) cranial nerve palsy was observed in all the patients; temporary VI, in two patients; temporary VII, in two patients, temporary hemiparesis, in one patient, temporary gait ataxia, in three patients; and persistent gait ataxia, in one patient. All patients had total tumor removal as assessed at surgery and with postoperative enhanced computed tomography. Four patients were independent and able to carry on normal activity, and one patient was independent at home but not outside due to severe ataxia 4 months after the operation. The presigmoid sinus avenue to the petroclival region shortens the distance to the clivus, permits a multiangled exposure of this difficult surgical area, minimizes the amount of temporal lobe retraction, preserves the integrity of the transverse sinus, and allows for better preservation of the neurovascular structures. These factors translate into a high percentage of total tumor removal and a low incidence of permanent morbidity.     

Middle fossa transpetrosal-transtentorial approaches for petroclival meningiomas selective pyramid resection and radicality

Summary Fourty-two patients with petroclival meningioma were operated upon by the middle fossa transpetrosal-transtentorial approaches since 1977. Half of those showed tumour extension into the middle fossa and one-third in the cavernous sinus. Seventeen (40%) had a large tumour of 40 mm in diameter or larger, and 8 of those had a broad attachment from the clivus to petrous pyramid of the temporal bone. The site of pyramid resection was selected from three types, depending on the tumour location and the patients' pre-operative hearing. There was no surgical mortality. Significant risk of lower cranial nerves palsy was minimal and useful hearing was preserved in 18 out of 21 patients. The follow-up, an average of 4 and a half years, showed tumours were completely eradicated in 32 patients (76%) and there was regrowfh in 3 (7%). Thirty-four patients (81%) were independent, 3 disabled and only one died of rapid tumour regrowth. The most influential factor on surgical results was the extent to which the tumour had invaded the brain stem. The presence or absence of arterial encasement and of peritumoural oedema on MRI were important in the selection for radical surgery.     

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.     

The results of radiosurgical management of 72 middle fossa meningiomas

Summary Of 812 patients with intracranial tumours treated by radiosurgery during the period 1984–1990, 129 had meningiomas. Of these latter, 72 had middle fossa meningiomas. Patients with meningiomas treated by us since March 1990 are not included in this report since we established the investigative principle of a minimum of 30 months follow-up. Seventeen of the 72 patients were treated after incomplete surgical resection, and 21 for tumour regrowth. In 34 patients, radiosurgery was the primary treatment.The tumour volume was calculated by the ellipsoid method. It ranged from 0.588–76.346 ml. Radiosurgery was performed using the non-invasive stereotactic fixation head device (Greitz-Bergström) adapted to the Fixster frame, and dynamic irradiation performed with the linear accelerator, using especially designed collimators. The total tumour dose for each patient ranged from 15–45 Gy.The minimum follow-up was 2 1/2 years and the maximum 8 years. In 50 patients there was tumour shrinkage ranging from 24–91% of the initial tumour volume. Shrinkage was associated with central tumour necrosis in 11 of these 50 patients. In 18 patients the tumour volume remained stable. In 2 patients there was tumour progression and in 2 there was regrowth after initial reduction of tumour volume. There were no significant treatment complications.Radiosurgery is preferable to re-operation in recurrent meningiomas and indicated after incomplete surgical removal. In high risk patients, as well as in unresectable meningiomas, it is an obvious alternative to microsurgery.     

枕下乙状窦后-内听道上入路切除岩斜区脑膜瘤

目的介绍应用枕下乙状窦后-内听道上入路显微手术切除岩斜区脑膜瘤的显微手术技术。方法回顾性分析采用枕下乙状窦后-内听道上入路显微手术治疗的8例岩斜区脑膜瘤的临床资料,并对手术方法进行分析。结果肿瘤全切除6例,次全切除2例。术后新增脑神经损害2例,无手术死亡病例。结论枕下乙状窦后-内听道上入路是切除主体位于后颅窝、同时累及中颅窝的岩斜区脑膜瘤的安全有效的改良入路,娴熟的显微神经外科技术,熟练掌握入路的显微解剖可获得满意的手术疗效,有利于提高肿瘤切除率和疗效。     

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.     

Natural history of petroclival meningiomas

OBJECTIVE: For evaluation of the natural history of petroclival meningiomas, a cooperative retrospective study of 21 conservatively treated patients is reported. METHODS: All patients had petroclival meningiomas that were observed for at least 4 years, with regular clinical and radiological control examinations. The follow-up periods ranged from 48 to 120 months (mean, 82 mo; median, 85 mo). Functional evaluations were performed by using the Karnofsky index. Individual growth curves and rates were defined. RESULTS: Age and sex distributions and presenting symptoms were comparable to those of other studies. During follow-up monitoring, radiological tumor growth was observed in 76% of the cases. With 63% of the growing tumors, there was functional deterioration. We performed statistical analyses of demographic features, radiological findings, and functional deterioration. Severe functional deterioration was observed to be statistically significantly associated with infratentorial growth and increased growth rates. A change in the growth pattern often preceded functional deterioration. CONCLUSION: This study provides a better understanding of the natural course of petroclival meningiomas. The growth patterns of these tumors are unpredictable and variable. The exact factors influencing growth remain unclear. This study can contribute to the optimization of individual management of these tumors.     

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

Neurosurgical Review - 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...     

The selection of the optimal therapeutic strategy for petroclival meningiomas

BACKGROUND: Broad experience with the management of petroclival meningiomas was analyzed to optimize therapeutic strategy. METHODS: The records of 75 patients with petroclival meningioma were reviewed. The population was divided into a microsurgery group (n = 49), a radiosurgery group (n = 12), a radiation therapy group (n = 5), and an observation group (n = 9) according to the modality of primary treatment. In the microsurgery group, the tumor was completely resected in 10 patients. Eleven of the 39 patients with incomplete resections sequentially underwent adjuvant radiation therapy or radiosurgery. The median follow-up period was 86 months (range, 48-210 months). The median follow-up period of the radiosurgery, the radiation therapy, and the observation group was 52 months (range, 48-71 months), 56 months (range, 51-72 months), and 63 months (range, 53-68 months), respectively. Management outcomes were evaluated with respect to tumor control rate, neurological deficit, and functional status assessed by the Karnofsky Performance Score. RESULTS: In the microsurgery group, 11 (22.4%) patients eventually showed tumor progression. However, there was only one recurrence if adjuvant therapy was used after incomplete removal. The incidence of favorable outcomes for cranial neuropathies was better in the incomplete resection group (69.2%) than for patients in the complete resection group (20%, P = .032). Moreover, a favorable functional outcome predominated in the incomplete resection group (76.9%) compared with the complete resection group (30%, P = .049). The disease was stable in both the radiation therapy and the radiosurgery groups during the follow-up period, with functional status and cranial nerve function perfectly preserved in these patients. No predictive factor other than short symptom duration was found to be significant. CONCLUSIONS: Because the growth rate of petroclival meningioma is low and good functional status can be guaranteed, intended incomplete resection should be considered as an acceptable treatment option. Adjuvant treatment after surgery is useful in the control of residual tumors. Radiosurgery may be appropriate as the primary treatment in asymptomatic patients with small tumor; however, more aggressive treatment is needed in young patients or patients with short symptom durations.     

Extended lateral subtemporal approach for petroclival meningiomas: report of experience with 24 cases

Subtemporal craniotomy centred on the external ear canal and its basal extension, involving resection of the roots of the zygomatic arch, roof of the external ear canal and superior third to half of the mastoid bone was used to treat surgically 24 meningiomas located in the petroclival region, having their maximum bulk at the level of tentorium. The approach was found to be suitable for dealing with middle fossa extensions of the tumour in addition to the part extending up to the mid-clivus or vertebrobasilar junctional region. The direction of the approach to the petroclival region was the shortest and most perpendicular from surface and avoided any neural or vascular exposure or manipulation. The basal exposure was horizontally wide and significantly low, which reduced the operating distance, limited the extent of temporal lobe retraction and provided additional space for manipulation of instruments. The exposure was manoeuverable with anterior, posterior and medial expansion being possible during or prior to tumour resection. The approach had the advantage of being simple and relatively quick, and of its familiarity to general neurosurgeons. The experience with the approach with petroclival meningiomas and its possible advantages over other available approaches to these lesions are analysed in this report.     

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.