En bloc resection of the temporal bone by the lateral approach in carcinoma of the middle ear associated with skull base infiltration with reference to the resection of the petrous apex

En bloc resection of the temporal bone was performed by the lateral approach on two patients with carcinoma of the middle ear, which was associated with destruction in the temporal bone and tumor infiltration of the cranial base. In one of the patients, the petrous apex was resected along with the temporal bone.En bloc resection on the temporal bone with the petrous apex is believed to be difficult because the internal carotid artery (ICA), cavernous sinus, and the brainstem are adjacent to each other in the petrous apex. However, the intra- and extracranial surgical procedures by this approach allow resection of the temporal bone ranging from the anterior part including the petrous apex to the posterior part including the mastoid process, the dura of the middle and posterior cranial fossae, and the sigmoid sinus, without exposure of the tumor. Special attention should be paid to the procedural points of surgery, such as, exposure of the petrous ICA, bleeding from the petrous sinus, and dural suturing in the vicinity of the apex. With regard to surgical indication, it is important to determine whether tumor infiltration is confined to the temporal bone and the dura of the middle and posterior fossa. If tumor infiltration into the petrous ICA, the dominant side of sigmoid sinus and/or the inferior cranial nerve is observed, then indication for surgery should be determined in a more critical manner.     

En Bloc Resection of the Temporal Bone by the Lateral Approach in Carcinoma of the Middle Ear Associated with Skull Base Infiltration with Reference to the Resection of the Petrous Apex

En bloc resection of the temporal bone was performed by the lateral approach on two patients with carcinoma of the middle ear, which was associated with destruction in the temporal bone and tumor infiltration of the cranial base. In one of the patients, the petrous apex was resected along with the temporal bone.

En bloc resection on the temporal bone with the petrous apex is believed to be difficult because the internal carotid artery (ICA), cavernous sinus, and the brainstem are adjacent to each other in the petrous apex. However, the intra- and extracranial surgical procedures by this approach allow resection of the temporal bone ranging from the anterior part including the petrous apex to the posterior part including the mastoid process, the dura of the middle and posterior cranial fossae, and the sigmoid sinus, without exposure of the tumor. Special attention should be paid to the procedural points of surgery, such as, exposure of the petrous ICA, bleeding from the petrous sinus, and dural suturing in the vicinity of the apex. With regard to surgical indication, it is important to determine whether tumor infiltration is confined to the temporal bone and the dura of the middle and posterior fossa. If tumor infiltration into the petrous ICA, the dominant side of sigmoid sinus and/or the inferior cranial nerve is observed, then indication for surgery should be determined in a more critical manner.

     

Extradural neuromas at the petrous apex: report of two cases

OBJECTIVE AND IMPORTANCE: Two rare cases of middle cranial fossa neuroma located in the epidural space at the petrous apex are reported. CLINICAL PRESENTATION: Two women, aged 58 and 49 years, were admitted to our hospital with diagnoses of cavernous sinus tumor. Analysis of preoperative computed tomography scans showed bone erosion of the petrous apex, and magnetic resonance imaging demonstrated the presence of an extradural mass located along the course of the petrous internal carotid artery in both patients. INTERVENTION: The tumor was completely removed in one patient and partially removed in the other by use of the epidural middle cranial fossa transpetrosal approach. In both patients, histological examination of tumor specimens revealed neuroma. CONCLUSION: Because surgical exploration revealed that these epidural tumors adhered tightly to the internal carotid artery, and because they had no relationship to the trigeminal nerve, facial nerve, or proximal greater superficial petrosal nerve, in our opinion, these tumors originated from the distal portion of the greater superficial petrosal nerve or the deep petrosal nerve. These neuromas were mainly found in a site under the cavernous sinus at the petrous apex, a location not previously reported.     

Epidermoid tumor originating from the petrous bone: report of two cases

In case 1, the tumor was incidentally found in the right petrous bone, middle cranial fossa and cerebello-pontine angle. T1 weighted MRI demonstrated a low intense mass and T2 weighted imaging demonstrated hyperintensity. Through the subtemporal extradural approach, an epidermoid in the middle cranial fossa was partially removed. Postoperative course was uneventfull but an episode of rhinorrhea occurred 15 months later. Bone-window CT scan disclosed air cells of the petrous bone were exposed to the previous surgical cavity. Using the same approach, an epidermoid was totally removed. With the sealing of the tumor cavity with the vascularized muscle flap, the patient became free from rhinorrhea. Case 2 had complainted of sensory impairment in the left trigeminal nerve distribution, atrophy of the left temporal and masseter muscle, and diplopia. T1 weighted imaging of MRI demonstrated a low-intense mass in the left petrous bone, middle cranial fossa, temporal lobe, and cerebello-pontine angle, and T2 weighted imaging demonstrated hyperintensity. The intradural tumor under the temporal lobe was removed at another hospital. As the diplopia deteriorated 5 years later, the patient was re-introduced to our hospital. At first, the tumor in the cerebello-pontine angle was removed using the left retromastoid lateral suboccipital approach. Later, the tumor in the petrous bone and middle cranial fossa was removed through the left subtemporal extradural approach. With the sealing of the tumor cavity with the vascularized muscle flap, postoperative cerebrospinal fluid leakage was prevented. The epidermoid tumor in the petrous apex is a congenital and rare disease. The obstruction of the petrous air cell and dural defect using the vascularized flap is most important to prevent postoperative cerebrospinal fluid leakage.     

Surgical anatomy of the extended middle cranial fossa approach

The extended middle cranial fossa approach includes removal of the petrous bone from its subtemporal surface in order to expose widely the internal auditory canal and the posterior fossa dura around its porus while preserving all the important and closely related anatomical structures. We have dissected 25 temporal bones and five fresh cadavers in order to define the limits of this approach. Measurements were obtained between the different structures to find reliable angles and distances that could guide working in this area. A new method of identification of the internal auditory canal is discussed based on the measurements taken.The results of the present work showed wide variations in the different structures. The arcuate eminence was coincident with the superior semicircular canal in only 48% of bones. Dehiscence of the geniculate ganglion and of the internal carotid artery was noted in 16% and 20% of specimens, respectively. The angles measured between the different structures showed great variations. However, the angle between the internal auditory canal and superior petrosal sinus was constant. Though the extended middle cranial fossa is a versatile approach, it affords a limited access to the cerebellopontine angle. A thorough understanding of the complex and variable anatomy of this area is necessary should this approach be utilized.     

Primary sphenoid and petrous apex esthesioneuroblastoma: case report

A 62-year-old woman presented with raised intracranial pressure and features of a right cerebellopontine angle tumour with extension into the right middle cranial fossa. The patient died before a surgical excision could be performed. The autopsy revealed a primary esthesioneuroblastoma of the sphenoid sinus eroding the petrous bone and extending into the middle cranial fossa with metastatic tumour in the liver, and paratracheal and hilar lymph nodes. Although rare, esthesioneuroblastoma must be considered in the differential diagnosis of petrous-sphenoid lesions.     

Surgical removal of giant acoustic neurinomas involving the skull base. Report of two cases

Neurinomas arising from the peripheral branch of the acoustic nerve distal to the internal auditory canal in the temporal bone are rare. Two advanced skull-base neurinomas are described which were situated mainly in the temporal petrous bone, and extended to the parapharyngeal space anteriorly, to the lateral cervical portion inferiorly, into the sphenoidal sinus medially, and into the middle and posterior cranial fossae compressing the brain stem. Both patients had been deaf for several years without other neurological deficits. The operative findings revealed that the fifth, seventh, and caudal cranial nerves were intact; therefore, it was suspected that these neurinomas originated primarily within the cochlea or the vestibule in the temporal bone. The tumors were completely removed via an extradural approach, with good results. Since the surgical treatment of such advanced skull-base neurinomas is difficult, the operative infratemporal fossa approach is described in detail.     

Petrous Bone Cholesteatoma

Petrous bone cholesteatoma is a rare pathologic entity and may be a difficult surgical challenge because of potential involvement of the facial nerve, carotid artery, dura mater, otic capsule, and risk of cerebrospinal fluid leak. The objective of this article is to present a personal classification of petrous bone cholesteatomas, a survey of recent surgical attitudes, and our present surgical strategy based on our experience with 54 operations between 1978 and 1990. Radical petromastoid exenteration with marsupialization and the middle cranial fossa approach were used only for small pure infra- or supralabyrinthine cholesteatomas, respectively. The enlarged transcochlear approach with closure of the external auditory canal was used for infralabyrinthine, infralabyrinthine-apical, and massive petrous bone cholesteatomas. Five cases with petrous bone cholesteatomas in different locations are described in detail to present the signs and symptoms together with the management.     

Petrous bone cholesteatoma

Petrous bone cholesteatoma is a rare pathologic entity and may be a difficult surgical challenge because of potential involvement of the facial nerve, carotid artery, dura mater, otic capsule, and risk of cerebrospinal fluid leak. The objective of this article is to present a personal classification of petrous bone cholesteatomas, a survey of recent surgical attitudes, and our present surgical strategy based on our experience with 54 operations between 1978 and 1990. Radical petromastoid exenteration with marsupialization and the middle cranial fossa approach were used only for small pure infra- or supralabyrinthine cholesteatomas, respectively. The enlarged transcochlear approach with closure of the external auditory canal was used for infralabyrinthine, infralabyrinthine-apical, and massive petrous bone cholesteatomas. Five cases with petrous bone cholesteatomas in different locations are described in detail to present the signs and symptoms together with the management.     

The Middle Fossa Transpetrous Approach for Petroclival Meningiomas

Seventeen patients with petroclival meningioma were operated on through a middle fossa transpetrous approach. This approach exposes the anterior cerebellopontine angle through a middle fossa craniotomy with removal of the petrous apex medial to the cochlea and petrous carotid artery. This approach may be enlarged by transection of the superior petrosal sinus and tentorium. The surgical technique and application of the middle fossa transpetrous approach for petroclival meningiomas is presented.     

The middle fossa transpetrous approach for petroclival meningiomas

Seventeen patients with petroclival meningioma were operated on through a middle fossa transpetrous approach. This approach exposes the anterior cerebellopontine angle through a middle fossa craniotomy with removal of the petrous apex medial to the cochlea and petrous carotid artery. This approach may be enlarged by transection of the superior petrosal sinus and tentorium. The surgical technique and application of the middle fossa transpetrous approach for petroclival meningiomas is presented.     

Surgical Anatomy of the Extended Middle Cranial Fossa Approach

The extended middle cranial fossa approach includes removal of the petrous bone from its subtemporal surface in order to expose widely the internal auditory canal and the posterior fossa dura around its porus while preserving all the important and closely related anatomical structures. We have dissected 25 temporal bones and five fresh cadavers in order to define the limits of this approach. Measurements were obtained between the different structures to find reliable angles and distances that could guide working in this area. A new method of identification of the internal auditory canal is discussed based on the measurements taken.

The results of the present work showed wide variations in the different structures. The arcuate eminence was coincident with the superior semicircular canal in only 48% of bones. Dehiscence of the geniculate ganglion and of the internal carotid artery was noted in 16% and 20% of specimens, respectively. The angles measured between the different structures showed great variations. However, the angle between the internal auditory canal and superior petrosal sinus was constant. Though the extended middle cranial fossa is a versatile approach, it affords a limited access to the cerebellopontine angle. A thorough understanding of the complex and variable anatomy of this area is necessary should this approach be utilized.

     

Surgical approaches to the cavernous sinus: a microsurgical study

The surgical approaches to the cavernous sinus were examined in 50 adult cadaveric cavernous sinuses using magnification of X3 to X40. The following approaches were examined: 1) the superior intradural approach directed through a frontotemporal craniotomy and the roof of the cavernous sinus; 2) the superior intradural approach combined with an extradural approach for removing the anterior clinoid process and unroofing the optic canal and orbit; 3) the superomedial approach directed through a supraorbital craniotomy and subfrontal exposure to the wall of the sinus adjacent to the pituitary gland; 4) the lateral intradural approach directed below the temporal lobe to the lateral wall of the sinus; 5) the lateral extradural approach for exposure of the internal carotid artery in the floor of the middle cranial fossa proximal to the sinus; 6) the combined lateral and inferolateral approach, in which the infratemporal fossa was opened and the full course of the petrous carotid artery and the lateral wall of the sinus were exposed and; 7) the inferomedial approach, in which the medial wall of the sinus was exposed by the transnasal-transsphenoidal route. It was clear that a single approach was not capable of providing access to all parts of the sinus. The intracavernous structures best exposed by each route are reviewed. The osseous relationships in the region were examined in dry skulls. Anatomic variants important in exposing the cavernous sinus are reviewed.     

Extradural middle fossa approach. Proposal of a learning method: the "rule of two fans." Technical note.

The extradural middle fossa approach is used to access lesions of the petroclival and cavernous sinus regions. It may be included in combined petrosal and anterolateral transcavernous approaches. Technically, it is a demanding exposure that provides a wide extradural corridor between the 5th, 7th, and 8th cranial nerves. Its major advantages are that it offers extradural dissection, limits temporal lobe retraction, and avoids the transposition of nerves or vessels. Its disadvantages are primarily related to the complicated anatomy of the petrous apex from the middle fossa trajectory, which can be unfamiliar to neurosurgeons. To facilitate the first attempts with this relatively uncommon approach during dissections of human cadaveric injected heads and isolated temporal bones, we developed a simple learning method useful for localizing all anatomical structures. Using this "rule of two fans," vascular, nervous, fibrous, and osseous structures are localized within two bordering fans with a 90-degree relationship to each other.     

Petrectomy of the point during approach to the clivus: technic, values and limitations. Apropos of a case of meningioma

A voluminous clivus meningioma was removed by a middle fossa transpetrous approach. We describe the surgical technique, with its advantages and its limits. The petrous bone was burred between the internal auditory canal, the internal carotid artery, the superior petrosal sinus and the inferior petrosal sinus. This approach gives excellent exposure of the clivus, anterior to the brainstem and the cranial nerves. This approach can be used for removal of voluminous intradural tumors arisen anterior to the internal auditory canal, and for clipping of aneurysms of the basilar artery. It appeared that the choice of the side for this approach must only depend on the extension of the tumour and displacements of the brainstem and the basilar artery, without concern on the hemispheric lateralization.     

Endoscopic balloon dilation as an adjunct to extended endoscopic approaches to the skull base

Cholesterol granulomas (CGs) are benign, expanding cystic lesions surrounded by a thick fibrous capsule and filled with fluid, formed by the degradation of blood elements. The goal of surgery is to open the granuloma widely, creating a well-drained cavity. The endonasal endoscopic approach for this extradural lesion is a minimal access method for surgical removal or fenestration. The role of balloon dilation in creating a wide fenestration has not been previously described. The authors describe a patient with a recurrent petrous apex CG who underwent an endoscopic, endonasal, transmaxillary transpterygoid approach to the petrous apex. A balloon sinuplasty catheter was used to dilate the surgical fenestration to maintain continued patency. The authors report on their first experience using balloon dilation combined with endoscopic drainage of the petrous apex. The excellent surgical outcome of this minimally invasive technique holds promise for future endonasal approaches to the middle cranial fossa.     

Transzygomatic Approach with Intraoperative Neuromonitoring for Resection of Middle Cranial Fossa Tumors

The authors reviewed the surgical experience and operative technique in a series of 11 patients with middle fossa tumors who underwent surgery using the transzygomatic approach and intraoperative neuromonitoring (IOM) at a single institution. This approach was applied to trigeminal schwannomas (n = 3), cavernous angiomas (n = 3), sphenoid wing meningiomas (n = 3), a petroclival meningioma (n = 1), and a hemangiopericytoma (n = 1). An osteotomy of the zygoma, a low-positioned frontotemporal craniotomy, removal of the remaining squamous temporal bone, and extradural drilling of the sphenoid wing made a flat trajectory to the skull base. Total resection was achieved in 9 of 11 patients. Significant motor pathway damage can be avoided using a change in motor-evoked potentials as an early warning sign. Four patients experienced cranial nerve palsies postoperatively, even though free-running electromyography of cranial nerves showed normal responses during the surgical procedure. A simple transzygomatic approach provides a wide surgical corridor for accessing the cavernous sinus, petrous apex, and subtemporal regions. Knowledge of the middle fossa structures is essential for anatomic orientation and avoiding injuries to neurovascular structures, although a neuronavigation system and IOM helps orient neurosurgeons.     

Combined therapy with surgery and stereotactic radiosurgery for facial schwannoma: case report

The authors report the successful case of combined therapy using surgery and stereotactic radiosurgery for facial schwannoma in the middle cranial fossa, and discuss the surgical strategy for preservation of facial nerve function. This 27-year-old man presented with a 9-year history of right facial palsy and spasm. CT scan and MR imaging demonstrated a tumor 3 x 3 x 4 cm in size extending to the intradural middle cranial fossa from the petrous bone. After total removal of the intradural tumor, gamma knife radiosurgery was performed for residual tumor in the petrous bone. The marginal dose to the tumor was 12 Gy. Facial spasm disappeared, but facial palsy is unchanged 14 months after the radiosurgery.     

A novel treatment approach to cholesterol granulomas. Technical note

The authors report a novel technique for the treatment of cholesterol granulomas. An extradural middle fossa approach was used to access the granuloma, with drainage through silastic tubes into the sphenoid sinus via the anteromedial triangle between V1 and V2. Cholesterol granulomas occur when the normal aeration and drainage of temporal bone air cells is occluded, resulting in vacuum formation and transudation of blood into the air cells. This process results in anaerobic breakdown of the blood with resulting cholesterol crystal formation and an inflammatory reaction. Traditional treatment of this lesion involves extensive drilling of the temporal bone to drain the granuloma cyst and establish a drainage tract into the middle ear. Such drainage procedures can be time consuming and difficult, and potentially involve structural damage to the inner ear and facial nerve. An extradural middle fossa approach provides easy access to the granuloma and anterior petrous bone entry into the granuloma for resection. Granuloma drainage is then achieved using shunt tubing in the sphenoid sinus via a small hole in the anteromedial triangle between V1 and V2. Five patients with symptomatic cholesterol granuloma were treated without complication using this novel extradural middle fossa approach. One patient required reoperation 1-year postoperatively for cyst regrowth and occlusion of the drainage tube. At the 5-year follow-up examination, no patient reported recurrent symptoms. Extradural middle fossa craniotomy and silastic tube drainage into the sphenoid sinus is a viable alternative method for treatment of cholesterol granuloma.     

Temporopolar epidural transcavernous transpetrous approach. Technique and indications

BACKGROUND AND PURPOSE: Several selective approaches have been recommended for access to the petroclival region (PCR). However, locoregional extension of the tumor may necessitate more extensive procedures. Dissections from injected specimens allowed us to describe the different osteodural triangles that are exposed to provide an extensive access to the PCR. METHOD: The bony step included a temporopterional flap and exposure of the paraclinoid carotid after removal of the anterior clinoid process. The sphenoid wing was then extensively drilled, exposing the foramen rotundum and ovale. An anterior petrosectomy was subsequently performed. The dura propria of the cavernous sinus was elevated as far as the Meckel cave. The sylvian fissure was also opened. Then, the temporobasal dura and the dura from the posterior surface of the petrous bone were opened and the superior petrosal sinus was coagulated and divided. The tentorium was divided toward its free edge. RESULTS: Via this approach, cranial nerves from the olfactory tract to the acousticofacial bundle are exposed. In the same way, the ventral and lateral surface of the pons is identified. CONCLUSION: The epidural temporopolar transcavernous transpetrous approach is useful to expose during the same procedure, elements of the posterior and middle cranial fossa. It is of particular value when managing tumors simultaneously involving the PCR, the parasellar, and the suprasellar regions.