Zygomaticotemporal approach to the basis cranii and basilar artery

Accessing the basilar artery apex: is the temporopolar transcavernous route an anatomically advantageous alternative?

The restricted operative field, difficulty of obtaining proximal vascular control, and close relationship to important anatomic structures limit approaches to basilar apex aneurysms. We used a cadaveric model to compare three surgical transcavernous routes to the basilar apex in the neutral configuration. Five cadaveric heads were dissected and analyzed. Working areas and length of exposure provided by the transcavernous (TC) approach via pterional, orbitozygomatic, and temporopolar (TP) routes were measured along with assessment of anatomic variation for the basilar apex region. In the pterional TC and orbitozygomatic TC approaches, the mean length of exposure of the basilar artery measured 6.9 and 7.2 mm, respectively (p = NS). The mean length of exposure in a TP TC approach increased to 9.3 mm (p < 0.05). Compared with the pterional and orbitozygomatic approaches, the TP TC approach provided a larger peribasilar area of exposure ipsilaterally and contralaterally (p < 0.05). The multiplanar working area related to the TP TC approach was 77.7 and 69.5% wider than for the pterional TC and orbitozygomatic TC, respectively. For a basilar apex in the neutral position, the TP TC approach may be advantageous, providing a wider working area for the basilar apex region, improving maneuverability for clip application, fine visualization of perforators, and better proximal control.

Zygomatic anterior subtemporal approach for lesions in the interpeduncular cistern

The interpeduncular cistern is a difficult region to approach through conventional methods due to its deep location and important adjacent neurovascular structures. Therefore, it is usually difficult to expose the region sufficiently. Technical problems associated with various surgical approaches have led to emergence of combined approaches and their modifications (i.e., the removal of the zygomatic arch). In addition, a frontotemporal craniotomy is reported to provide a wide exposure of the anterior temporal base, thus allowing oblique access to the interpeduncular cistern with minimal brain retraction. This study describes clinicians' experience and the surgical results of 24 patients who underwent a zygomatic anterior subtemporal approach.

Anatomo-radiological evaluation of lateral approaches to the skull base

Our objective is to correlate the anatomical exposure provided by complex skull base approaches to the lateral skull base with their CT and MRI scans counterparts and to introduce a modular concept emphasizing the derivation of complex skull base approaches from simpler ones.We executed 10 lateral approaches to the skull base in 20 embalmed cadaveric heads (40 sides). Each approach was executed a minimum of three times on each specimen. These approaches were the pterional and its modifications, the subtemporal and its modifications, and the suboccipital and its modifications. We correlated the approaches and the areas of the skull base exposed by scanning the surgical cavity filled with material imageable by CT and MRI and throughly surveying the operative field.Visualization of the area of the skull base exposed was excellent using our CT-MRI imageable cadaveric preparation. The topographic areas of the skull base exposed correlated well with their radiological counterparts.The areas of the skull base exposed by each of the complex surgical approaches to the skull base were clearly delineated by using our anatomo-radiological correlation. Complex approaches to the skull base are formed by simple neurosurgical approaches (building blocks) to which different modules are added.

[Fronto-temporo-orbito-zygomatic approach - analysis of the surgical technique on cadaver simulations]

This paper presents consecutive stages of the fronto-temporo-orbito-zygomatic approach (FTOZA). Two simulations of FTOZA were performed on non-fixed human cadavers without any known pathologies in the head and neck. The consecutive stages of the procedure were documented with photographs and schematic diagrams. The starting point for FTOZA is a pterional craniotomy and osteotomy including the orbital rim, body of the zygomatic bone and zygomatic arch. In justified cases it is also possible to temporarily remove the upper and lateral walls of the orbit. Wide drawing apart of the Sylvian fissure is an important supplement of the approach. The fronto-temporo-orbito-zygomatic approach is a reproducible technique, which provides surgical penetration of the middle cranial fossa and related regions. This approach is particularly useful in the treatment of tumours of the above-mentioned anatomical areas as well as vascular malformation of the posterior part of the arterial circle of the brain.

Interactive 3D stereoscopic digital-image analysis of the basilar artery bifurcation

The goal of this study was to analyze morphometrical variations of the basilar artery bifurcation (BAB), so that physicians could map out a patients anatomical structure prior to delicate neurosurgical procedures. The CT-angio files of 98 patients ranging from 12 to 78 years of age were retrieved. These files were evaluated using Gradual Angiographic Image Data Analyzer (GAIDA) software, where a new interactive three-dimensional (3D) stereoscopic visualization method was used to reconstruct computer images of the BAB complex. Subsequently the measurements of the BAB angles and BAB distances in relation to the dorsum sellae (DS), posterior clinoid processes (PCPs), and posterior biclinoid plane (PBP) were carried out. The average BAB angle was determined to be 117.7 degrees (30.93 degrees -172.2 degrees ). The three types of BAB were classified as type T with a BAB angle greater than 145 degrees (mean 154.4 degrees ), type Y for an angle being equal or less than 145 degrees but greater than 100 degrees (mean 121.5 degrees ) and type V for angles less than 100 degrees (mean 83.28 degrees ). The mean distances between BAB and DS (9.55 mm), BAB and left PCP (12.97 mm), and BAB and right PCP (13.01 mm), BAB and PBP (2.2 mm) were evaluated. Furthermore, the BAB is of great importance when examining basilar artery aneurysm development, particularly at the point of greatest hemodynamic stress, as well as the BAB distances in relation to the bony landmarks used for different approach methods in neurosurgical procedures.

Microsurgical and endoscopic approaches to the basilar bifurcation: quantitative comparison of combined pterional/anterior temporal and orbitozygomatic extended approaches

To determine the most effective route to the upper third of the basilar artery, 10 cadaver dissections were performed comparing the exposure gained using the combined pterional/anterior temporal approach and the orbitozygomatic extended approach. Endoscopic evaluation through an eyebrow incision in each dissection helped determine whether any advantage was conferred by the cranial base approach. This also served to assess the benefit of using the endoscope as an adjunct to open procedures in evaluating the opticocarotid and retrocarotid routes to the basilar artery. The results of cadaveric dissections suggest that compared with the exposure afforded by the combined pterional/anterior temporal approach, the orbitozygomatic extended approach yields an increase of 8 cm in the anteroposterior axis and 10 cm in the superoinferior axis. Furthermore, as expected, the increases in visibility were directed anteriorly and posteriorly. When employed through the craniotomy site during aneurysm clipping, endoscopy was found to be potentially useful in assessing the contralateral elements of the upper basilar complex.

Subtemporal approach to the tentorial incisura: normative morphometric data based on magnetic resonance imaging scans

OBJECTIVE

The tentorial notch can be contained within a transversal line made in front of the cerebral peduncles and another line through the posterior border of the quadrigeminal plate into the anterior, middle and posterior parts. Different approaches to the tentorial incisura have been established. The subtemporal approach represents one of those options. Since morphometrical analyses of this approach in this region have not yet been performed, the aim of the present study was to measure the surgical corridor along these borders.

METHODS

Fifty-three magnetization prepared rapid acquisition gradient echo-sequences of individual brains without pathological lesions were analyzed. For this study, an axial section along the pontomesencephalic sulcus and two coronal sections along the above-described borders were measured using a program specially written by one of the coauthors to obtain various parameters. A triangle circumscribing the surgical corridor was delimited by exactly defined anatomic landmarks for the coronal section, and the depths of the temporal lobe at the incisural borders were measured for the axial section.

RESULTS

Various data are given concerning the surgical corridor of a subtemporal approach to the tentorial incisura. The different shapes of this corridor to the incisural region were recorded. According to our measurements, four different types of the temporal lobe could be differentiated.

CONCLUSION

Knowledge of these distances and various contours of the path is crucial to avoid brain damage during retraction or manipulation. The curvature of the floor of the middle cranial fossa is highly variable and thus determines the surgical path chosen.

Lateral Transmandibular Approach to the Skull Base in Children: Three Case Reports

The choice of surgical approach to tumors of the cranial base in children is determined by strict criteria. The criteria include optimal visibility for the surgeon, minimal possible impairment of facial skull growth, and the preservation of motor and sensory nerve integrity. From 1993 to 1996, three children (6 years old, 22 months old, 6 months old, respectively) underwent surgery to resect cranial base tumors through a modified lateral transmandibular approach. In all three patients a preauricular incision with temporal and submandibular extensions was performed. After the mandible was prepared, an osteotomy was conducted cranially to the mandibular foramen. When the capitulum was temporarily disarticulated, wide access to the cranial base was provided and the tumors were resected. Two of these children were available for follow-up, and we continue to observe their development. Given the severity of their conditions, treatment yielded good results. Growth impairment of the mandible was corrected by the distraction osteogenesis technique.

Surgical approaches to suprasellar and parasellar tumors

Uncommonly, pituitary tumors require a complex intracranial approach. In such instances of extensive para- and suprasellar involvement, an approach that incorporates basic techniques enhanced by developments in contemporary cranial base surgery is effective. Tumors with extensive invasion of the cavernous sinus unilaterally are generally best approached by a frontotemporal transcavernous strategy. Those with bilateral cavernous sinus involvement are better suited for a bifrontal transbasal type of approach. Supra-sellar tumors are best exposed by a strategy that affords the surgeon an adequate inferior-to-superior viewing angle, which is generally accomplished by removal of all or part of the orbital rim. These approaches yield benefits in decreased frontal lobe retraction, which may be particularly important in cases requiring a bilateral approach. Finally, some tumors with more modest extensions outside the bounds of the sella are now treated with a more minimalistic type of approach via a small incision in the eyebrow. This marks a move toward a "minimally invasive" type of strategy. Sound judgment based on adequate experience with these approaches must be exercised to ensure appropriate application of this strategy.

Craniofacial access to the anterior and middle cranial fossae and skull base

A profusion of surgical approaches to gain access to the anterior and middle cranial fossa and skull base have been described. An attempt has been made to simplify the position by suggesting a classification of surgical approaches and to describe a standard approach (of at most 4 defined osteotomies, or at least 2) to give a craniofacial approach to the anterior and middle cranial fossae, the infratemporal fossa, the orbit and the superior nasal cavity. The full extent of the osteotomies have been likened to an ancient Corinthian face mask, or to the stylized face-mask worn by the comic book hero, Batman.

The transzygomatic approach: an anatomical study

The transzygomatic approach has been utilised to facilitate neurosurgical access to the skull base for a number of years. Advocates of the technique claim the additional access gained provides wider exposure of the neurosurgical pathology and improved visualisation of adjacent vital neurovascular structures. The aim of this study was to photographically demonstrate the technique and to highlight the anatomical areas to which access can be improved. A morphological cadaver study was undertaken. Specific intracranial structures in the vicinity of the skull base were targeted and exposure was compared with and without the zygoma in position. This study demonstrates the increase in exposure of the basilar bifurcation (via a transsylvian approach) and the P2 segment of the posterior cerebral artery (via a subtemporal approach) that can be achieved and the improved access to adjacent anatomical compartments. It can be concluded that the transzygomatic approach is a relatively simple technique which can readily increase exposure of the skull base. It also provides simultaneous access to the superior pole of the infratemporal fossa, the pterygopalatine fossa and the orbit.

Technical aspects and recent trends in the management of large and giant midbasilar artery aneurysms

OBJECTIVE

Cranial base approaches that involve radical petrosectomy are associated with significant rates of morbidity. We have sought alternative approaches to the midbasilar artery to reduce the extent of temporal bone removal and correspondingly to reduce complications while still providing adequate surgical exposure. The extended orbitozygomatic and far-lateral approaches are two such approaches. We compared our experience with these approaches to our experience with the standard transpetrosal approaches in the treatment of midbasilar artery aneurysms.

METHODS

Between 1990 and 1995, 28 patients with large and giant midbasilar artery aneurysms were treated with approaches involving either radical or conservative petrosectomy.

RESULTS

Overall, good outcomes (Glasgow Outcome Scale scores of 1 and 2) were observed in 21 patients (75%), and three patients (11%) had permanent treatment-associated neurological deficits. Four patients died. Later in the series, the pterional-subtemporal approach (four patients) was supplanted by the orbitozygomatic approach (six patients). The increased use of hypothermic circulatory arrest involved exposure of the midbasilar region from above (orbitozygomatic approach) and below (far-lateral approach, 13 patients). Concomitantly, the use of transpetrosal approaches (five patients) decreased.

CONCLUSION

Modified orbitozygomatic and far-lateral approaches adequately expose the midbasilar region and can replace transpetrosal approaches in some cases. These extended approaches can be associated with lower morbidity rates than can transpetrosal approaches. Hypothermic circulatory arrest is critical to clipping large and giant midbasilar artery aneurysms directly when approaches that conserve the temporal bone are used.

The effect of orbitozygomatic access for ruptured basilar and related aneurysms on management outcome

BACKGROUND

Despite increasing use of craniofacial access for complex intracranial and skull base pathology, there have been no reports detailing the impact of improved access on clinical outcome.

METHODS

Orbitozygomatic access was used in 32 patients with an aneurysm of the basilar bifurcation, superior cerebellar, or posterior cerebral arteries over a 9-year period.

RESULTS

Operative mortality was 0%, overall management mortality 9% and management morbidity was 9%. This approach was selected for these patients because of the anatomy of the aneurysm and its relationship to the terminal basilar complex and the dorsum sellae/posterior clinoid process. The flexibility achieved by the access allowed intraoperative use of multiple corridors of access. Morbidity directly attributable to the use of orbitozygomatic access was minimal.

CONCLUSIONS

While management outcome after aneurysmal subarachnoid hemorrhage relates directly to the severity of the initial hemorrhage, rather than the surgical approach chosen, in selected patients we recommend the use of this approach as a valuable adjunct to the armamentarium of the vascular neurosurgeon.

A surgical technique to avoid postoperative enophthalmos in the cranioorbital approach. Technical note

The authors describe a surgical technique to avoid postoperative enophthalmos when using the cranioorbital approach. To perform osteotomies with a less demanding technique, two separate bone flaps were created: 1) a free frontotemporal bone flap and 2) en bloc removal of the superior and lateral orbital rims: Because the latter bone flap includes both the orbital roof and the posterolateral wall of the orbit with the greater wing of the sphenoid bone, unnecessary bone defects in the lateral orbital wall are avoided. The technique has been performed in seven patients treated for medially located skull base neoplasms or complex anterior circulation aneurysms without postoperative enophthalmos or other cosmetic problems. The authors believe this cranioorbital approach, with its simpler, less invasive surgical technique, offers a definite advantage by avoiding postoperative enophthalmos.

The orbitozygomatic infratemporal fossa approach: a quantitative anatomical study

Using detailed cadaveric dissections this study has demonstrated and quantified the increase in exposure and additional access gained by using the orbitozygomatic infratemporal fossa approach for neurosurgical access. The surgical window of exposure can be increased by up to 300% when this technique is utilised to facilitate access via either a subtemporal (to access the P2 segment of the posterior cerebral artery) or transsylvian (to access the basilar bifurcation) approach. In addition the distance between the surgeon and the operative field can be decreased by approximately 2-3 cm. The orbitozygomatic infratemporal fossa approach is a relatively simple technique which can readily increase neurosurgical exposure of the skull base. It also provides simultaneous access to the infratemporal fossa, pterygopalatine fossa and the orbit.

The transzygomatic approach: a long-term clinical review

The transzygomatic approach has been utilised to improve access to the skull base, infratemporal fossa and orbit for a number of years. It provides a low anterolateral approach to the skull base, along the floor of the middle fossa. It allows both a transsylvian and subtemporal approach with a reduction in brain retraction and better exposure of adjacent neurovasculature structures. A long term review of 53 patients is presented highlighting outcome at two years post surgery and morbidity of the approach. It is concluded that the technique is versatile and can be used to improve exposure of a variety of anatomical locations. There is minimal long term morbidity attributable to the surgery of access and the majority of patients have had good outcomes.

The pretemporal approach to the interpeduncular and petroclival regions

A pretemporal approach to the interpeduncular and petroclival regions is described. Through a frontotemporal craniotomy based very low in the middle fossa the temporal lobe is completely exposed. The Sylvian, carotid, chiasmatic, and lamina terminalis cisterns are widely opened. The arachnoid fibers between the uncus and the frontal lobe, as well as those binding the temporal lobe to the tentorial edge and to the oculomotor nerve are also separated. The bridging veins from the temporal pole to the spheno-parietal sinus are usually coagulated and sacrificed allowing for posterior displacement of the temporal lobe. The approach combines the advantages of both the classical pterional and subtemporal approaches providing unhindered exposure of the anterior portion of the tentorial incisura in dealing with vascular and tumoural lesions arising at the sellar, parasellar, and interpeduncular regions, and at the superior aspect of the petroclival region.

Craniofacial osteotomies for skull base access

During a five year period 150 craniofacial access osteotomies for skull base access have been performed allowing direct exposure of pathology in difficult anatomical acreas with minimal complications. These approaches have been developed by considering the craniofacial skeleton as a single osteoplastic structure. Bone segments are mobilised and replaced using rigid fixation. In this way osteotomies can be planned which significantly improve access and preserve form and function in the complex region of the skull base.

Characteristics of pterional routes to basilar bifurcation aneurysm

In an attempt to clarify the characteristics of the pterional routes to the basilar bifurcation aneurysm, 65 consecutive surgical cases were retrospectively analyzed concerning the size of the aneurysm, the height of the aneurysm neck, the length of the clip blades, and the direction of clip application. Clipping was performed through the pterional route in 59 cases consisting of 14 opticocarotid and 45 retrocarotid routes. A subtemporal approach was performed for six low-positioned aneurysms. The opticocarotid approach was undertaken because of the following situations: 1) laterally protruded and/or highly sclerotic internal carotid artery (n = 8); 2) long, redundant A1 segment (n = 3); 3) an associated aneurysm of the internal carotid artery obstructing the retrocarotid space (n = 2); and 4) a short and/or large posterior communicating artery obstructing the retrocarotid space (n = 1). The range in height of the aneurysm neck was narrower in the opticocarotid approach (1-10 mm) than in the retrocarotid approach (-7-15 mm). The direction of clip application on the axial plane was more anteriorly deviated in the opticocarotid approach (41.4 +/- 12.8 degrees from the glabella-inion line) than in the retrocarotid approach (58.8 +/- 11.1 degrees; P = 0.01). The retrocarotid route (n = 45) was further subdivided into the medial or lateral retrocarotid routes, depending on the medial or lateral side to the posterior communicating artery, respectively. The medial retrocarotid approach (n = 9) made it possible to reach relatively high-positioned aneurysms (7.0 +/- 3.9 mm) compared with the lateral retrocarotid approach (4.2 +/- 4.7 mm; n = 29).(ABSTRACT TRUNCATED AT 250 WORDS)

Cranial base approaches to intracranial aneurysms in the subarachnoid space

The use of cranial base approaches to aneurysm surgery is illustrated by means of patient examples. Over a 9-year period, cranial base approaches were used to expose and treat 38 aneurysms involving the anterior communicating artery complex, proximal internal carotid artery, basilar artery, or vertebral artery. The approaches included orbital osteotomy, orbitozygomatic osteotomy, petrous apicectomy, presigmoid petrosectomy, and extreme lateral transcondylar methods. Complications related to the approaches included one partial ptosis and two cerebrospinal fluid leaks, which resolved with treatment. The technique of three-dimensional computed tomographic angiography was useful in delineating the vascular anatomy and its relation to the cranial base structures. This helped the surgeon plan the appropriate approach to the aneurysm. Cranial base approaches, used selectively, can provide improved exposure of deep-seated aneurysms and large or giant aneurysms, while minimizing brain retraction.

The temporo-polar approach to basilar artery aneurysms with or without zygomatic arch translocation

Since the publication of the temporo-polar approach to basilar artery aneurysms by Sano (1980 and 1987), various modifications of the approach were reported. The approach provides a better view and a wider operating field than the subtemporal or pterional ones. Usually the approach does not need temporary remove of the zygomatic arch. If however, a basilar tip aneurysm is located very high above the posterior clinoid, temporary removal of the zygomatic arch is necessary which is sutured back to its original position at the end of the operation.

A multidisciplinary approach to tumours involving the orbit: orbital re-construction, a 3-dimensional concept

Radical tumour removal in the region of the anterior skull base with involvement of the orbit requires not only good exposure but also acceptable reconstruction with good cosmesis, no visible scars and no injury to the eye. The possible approaches, which should be flexible and adapted to the location and extent of the pathology and the appropriate methods of reconstruction, are illustrated by four patients. The relevant literature is reviewed. Emphasis on the need for a 3-dimensional concept in the reconstruction and the importance of a multi disciplinary team is stressed.

Reconstruction following extensive removal of meningioma from around the orbit

Three patients with a meningioma involving the bone around the orbit are presented. The need for a complete resection and immediate reconstruction is emphasized. The principles of a 3-D orbital reconstruction are discussed.

An alternative surgical approach to aneurysms of the posterior cerebral artery

The value of a skull base approach (the transzygomatic approach) is assessed in the treatment of patients with posterior cerebral artery aneurysms. The operative approach is outlined, and the advantages and disadvantages of the procedure are discussed.

Chondrosarcoma of the skull base: a series of eight cases

Chondrosarcomas of the skull base are indolent, locally invasive tumors with a marked tendency to recur. Surgery is the mainstay of treatment because these tumors are generally resistant to other forms of treatment. A surgical approach with wide access to the skull base and one that is easily repeatable is required, because recurrence is common. We have used the LeFort I maxillotomy or mobilization of the zygoma at the time of craniotomy to obtain wide access to the skull base in eight cases of chondrosarcoma. Three patients have undergone subsequent procedures by us for recurrent disease. One patient died 30 days after the operation, and one has required an open repair of a cerebrospinal fluid leak. Good palliation of symptoms has been achieved in all survivors. These approaches fulfill the criteria for the surgical management of these difficult tumors by allowing excellent exposure, safe repetition if required, satisfactory palliation, and acceptable morbidity.

The zygomatico-temporal approach to the skull base: a critical review of 11 patients

The zygomatico-temporal approach to the base of the skull is a relatively new but established surgical technique. The approach involves the removal of the zygomatic bone to provide access to the skull base, middle cranial fossa, parasellar region and interpeduncular cistern with minimal brain retraction. An excellent view of the bifurcation of the basilar artery and suprasellar region is provided. The outcome of 11 patients undergoing this procedure is reported with particular reference to the post-operative morbidity and the cosmetic result.

A review of the management of 15 cases of aneurysms of the posterior cerebral artery

The presenting features of 15 cases of posterior cerebral artery aneurysm are discussed. The use of the axial radiographic view in determining the anatomy of these aneurysms is highlighted. Ten out of 15 patients underwent surgery. In three patients the aneurysm was approached by the transzygomatic route, in six via the subtemporal route and in one using the pterional approach. There was no operative mortality. Nine out of 10 patients made good long-term recoveries following surgery, one patient remains moderately disabled. Three out of five patients in the non-surgical group made a good recovery. The advantages and disadvantages of the various operative approaches are discussed with particular reference to ease of access, brain retraction and adequate exposure of the aneurysm. It was possible to clip the aneurysm and spare the parent vessel in all three cases using the transzygomatic approach, but this was possible in only one of the remaining cases.

Transfacial access for neurosurgical procedures: an extended role for the maxillofacial surgeon. II. Middle cranial fossa, infratemporal fossa and pterygoid space

A variety of osteoplastic flaps have been devised for transoral or extraoral access to the base of skull and the upper anterior cervical spine. Part I of this two-part review describes access to the clivus and upper anterior cervical spine. Part II will describe access to the middle cranial fossa, the infratemporal fossa and the pterygoid (retromaxillary) "space".

Adenoid cystic carcinoma of the infraspheno-temporal fossa. Latero-facial resection combined with multiple osteotomies

Two cases of Adenoid Cystic Carcinoma (ACC) of the infrasphenotemporal fossa with invasion of the floor of the middle fossa are presented. Preoperative studies included CT-scan and cervical and cerebral angiography. The exposure and operative management comprised a latero-facial approach combined with multiple exposure osteotomies of the ascending mandibular ramus, orbitozygomatic region and a frontosphenotemporal craniotomy. This approach provides wide exposure of the posterolateral orbit, sphenoid wing and infratemporal and pterygomaxillary fossa. One of our patients died from massive recurrence in proximity to the cavernous sinus and the other is free of disease after 30 months.

Modifications of temporal approaches: anatomical aspects of a microneurosurgical approach

All subtemporal approaches have in common the risk of temporal lobe damage. To reduce the retraction of the temporal lobe we combine two synergistic modifications of temporal approaches to reach the prepontine space. The first is the temporary resection of the zygomatic arch which allows to bring the temporalis muscle more caudally and subsequently allows an anterior subtemporal approach with only minimal temporal lobe retraction. The second modification is the resection of the apex of the petrous bone after incision of the tentorium. This provides an excellent view into the posterior fossa between the trigeminal nerve medially, the internal carotid artery caudally and the internal auditory canal laterally. The anatomical aspects of a microneurosurgical approach regarding these modifications are reported and discussed.

Modifications of temporal lobectomy according to the extent of epileptic foci and speech-related areas

The authors applied combined depth and subdural electrodes in patients with intractable complex partial seizures to detect the precise extent of epileptic foci and functionally map speech-related areas. The medial temporal structures were explored with depth electrodes and the lateral temporal cortex with subdural electrodes. On the speech-dominant side, electrical stimulation was given to demarcate the speech-related areas in the lateral temporal cortex. Based on these data, the extent of surgical resections was tailored to include as much of the epileptogenic areas as possible while preserving the functionally essential zones of the lateral cortex. According to the range of resection, three different approaches were employed for en bloc ablation of the lateral cortex and opening of the inferior ventricle. The results thus acquired have been satisfactory in terms of seizure control and the preservation of speech function.

Surgical management of midline skull-base tumors: a new approach

Many surgical approaches to the clivus and upper cervical spine have been used in the treatment of skull-base tumors over the past 50 years. However, the outcome of surgery has been complicated by difficulties of access to the whole clivus, together with pharyngeal wound breakdown with subsequent development of cerebrospinal fluid (CSF) fistula and meningitis. A technique described recently utilized Le Fort I osteotomy to improve exposure of the clivus in the approach to vertebrobasilar aneurysms, facilitating control of the aneurysm and reducing the risk of posttraumatic CSF fistula. The same approach, via maxillotomy, has permitted partial or total tumor resection in 13 consecutive procedures carried out at Atkinson Morley's Hospital on 10 patients presenting with tumors of the skull base. Neurological status was either improved or unchanged in all patients postoperatively, and pain relief was obtained in five of eight cases in which this was a presenting symptom. No patient developed a CSF fistula following surgery. Cosmetic results were good, and no problems related to malocclusion were reported. This approach may be used to advantage in the surgical treatment of skull-base tumors, at initial presentation, and can be repeated without undue difficulty should there be tumor recurrence.