Stylohamular dissection: a new method for en bloc reaction of malignancies of the infratemporal fossa

Modified Maxillary-Swing Approach for Resection of Primary Malignancies in the Pterygopalatine Fossa

Background

En bloc resection of malignancies in the pterygopalatine fossa (PPF) poses critical challenges. Using the modified maxillary-swing (MMS) approach, we achieved monobloc removal of primary malignancies in this region. This study provides a detailed account of the surgical techniques and indications used.

Methods

We enrolled seven patients with primary malignancies in the PPF during a period from January 2012 to January 2019 in this retrospective study. After malignancies were confirmed by biopsy as well as evaluation with computed tomography (CT) and magnetic resonance imaging (MRI) scans, all of the patients underwent MMS surgery under general anesthesia to extirpate these tumors. We performed regular postoperative follow-up using CT and MRI scans.

Results

En bloc resection was successfully performed in all cases. We observed negative margins in six cases and positive margins in one patient with adenoid cystic carcinoma, who received postoperative radiotherapy. The most common complication was facial numbness. During the follow-up period (range, 6-69 months), one patient suffered from recurrence, while the others did not.

Conclusion

The advantages of the MMS include a wide surgical field, full exposure, and easy manipulation. We expect this approach to become an alternative to the monobloc resection of malignancies in the PPF that involve the infratemporal fossa, maxillary sinus, nasal cavity, orbit, or oral cavity.

A lateral transzygomatic-transtemporal approach to the infratemporal fossa: technical note for mobilization of the second and third branches of the trigeminal nerve

This report describes an alternative approach to the infratemporal fossa lesions through a lateral zygomato-temporal craniotemy, which modifies the extradural temporopolar technique for cavernous sinus surgery. First, an L-shaped osteotomy of the zygoma from the frontozygomatic suture attaching the zygomatre arch and low positioned temporal cramotomy are made. Through this zygomato-temporal craniotomy and orbitotemporal drilling, leaving the lateral orbital rim and orbital roof intact, skeletonization of the foramens rotundum and ovale are carried out. The key element of this infratemporal exposure is the dissection and mobilization of the trigeminal nerve, trigeminal second branch rostrally, and the third branch caudally, which facilitates a wide exposure of the infratemporal fossa with preserving trigeminal function. The corridor between the mobilized trigeminal branches provides direct access to the lateral and medial pterygoid plate, internal maxillary artery, sphenoid and maxillary sinuses, maxilla and, finally, the parapharyngeal area. Our experiences have demonstrated that this lateral transzygomatic-transtemporal exposure is satisfactory for use with infratemporal fossa tumors. This approach has an advantage for cranial-base exposure with decreased risks of cosmetic deformity and of trigeminal nerve dysfunction.

Microanatomy and surgical approaches to the infratemporal fossa: an anaglyphic three-dimensional stereoscopic printing study

OBJECTIVE

The infratemporal fossa (ITF) is a continuation of the temporal fossa between the internal surface of the zygoma and the external surface of the temporal bone and greater wing of the sphenoid bone that is sitting deep to the ramus of the mandible. The principal structure to understanding its relationships is the lateral pterygoid muscle. Other important structures are the medial pterygoid muscle, the maxillary artery, the pterygoid venous plexus, the otic ganglion, the chorda tympani nerve and the mandibular nerve. In this study, we describe the microsurgical anatomy of the ITF, as viewed by step-by-step anatomical dissection and also through the perspective of three lateral approaches and one anterior surgical approach.

METHODS

Eight cadaver specimens were dissected. In one side of all specimens, an anatomical dissection was done in which a wide preauricular incision from the neck on the anterior border of the sternoclidomastoid muscle at the level of the cricoid cartilage to the superior temporal line was made. The flap was displaced anteriorly and the structures of the neck were dissected followed by a zygomatic osteotomy and dissection of the ITF structures. On the other side were the surgical approaches to the ITF. The combined infratemporal and posterior fossa approach was done in two specimens, the subtemporal preauricular infratemporal fossa approach in two, the zygomatic approach in two, and the lateral transantral maxillotomy in two. The anatomical dissections were documented on the three-dimensional (3D) anaglyphic method to produce stereoscopic prints.

RESULTS

The lateral pterygoid muscle is one of the principal structures to enable understanding of the relationships into the ITF. The tendon of the temporal muscle inserts in the coronoid process at the ITF. The maxillary artery is the terminal branch of the external carotid artery that originates at the neck of the mandible and runs into the parotid gland. In our dissections the maxillary artery was lateral to the buccal, lingual, and inferior alveolar nerves. We found the second part of the maxillary artery superficial to the lateral pterygoid muscle in all specimens The anterior and posterior branches of the deep temporal artery supply the temporal muscle. In two cases we found a middle deep temporal artery. The different approaches that we used provided different views of the same anatomical landmarks and this provides not only safer surgery but also the best choice to approach the ITF according with the pathology extension.

CONCLUSIONS

The ITF is a complex region on the skull base that is affected by benign and malignant tumors. The study through different routes is helpful to disclose the relationship among the anatomical structures. Although the authors have shown four approaches, there are a variety of approaches and even a combination of these can be used. This type of anatomical knowledge is essential to choosing the best approach to treat lesions in this area.

Direct and remote outcome after treatment of tumours involving the subtemporal fossa and related structures with the extended subtemporal approach

BACKGROUND AND PURPOSE

The aim of the study was to present our results of the surgical treatment of subtemporal fossa tumours and surrounding regions using the extended subtemporal approach.

MATERIAL AND METHODS

Twenty-five patients (10 women, 15 men) with subtemporal fossa tumours were included in the study. The neurological and performance status of the patients were assessed before and after surgery as well as at the conclu-sion of treatment. The approximate volume of the operated tumour, its relation to large blood vessels and cranial nerves, as well as consistency and vascularisation were assessed.

RESULTS

The symptom duration ranged from 2 to 80 months (mean: 14 months). In 44% of patients, headache was the predominant symptom. Less frequent symptoms were: paralysis of the abducent nerve and disturbances of the trigeminal nerve. Approximate volume of the tumours ranged from 13 to 169 cm3 (mean: 66 cm3). The most frequent histological diagnosis was meningioma (16%), followed by angiofibroma, neurinoma and adenocystic carcinoma (12%). Total or subtotal resection was achieved in 80% of patients.

CONCLUSIONS

The extended subtemporal approach allows for the removal of tumours of the subtemporal fossa and surrounding regions. This approach also allows one to remove tumours expanding in the regions surrounding the subtemporal fossa only. In such cases the subtemporal fossa constitutes the way of the surgical approach.

Microsurgical anatomy of the infratemporal fossa as viewed laterally and superiorly

OBJECTIVE

Benign tumors involving cavernous sinus, trigeminal nerve, and middle cranial fossa occasionally extend to the infratemporal fossa (ITF). In this study, we describe the microsurgical anatomy and dissection of the ITF, as viewed laterally and superiorly. We also describe a new bypass graft to the supraclinoid internal carotid artery using the internal maxillary artery (IMA), which is found in the ITF.

METHODS

Twelve cadaver specimens were used. Dissection required zygomatic arch osteotomy, downward displacement of the temporalis muscle, extensive subtemporal craniectomy, and mild elevation of the temporal lobe together with the dura.

RESULTS

The anatomic relationships between the lateral and medial pterygoid muscles and the neurovascular bundle of the ITF are demonstrated. The neurovascular bundle contains the IMA, which runs horizontally, and the main branches of the mandibular nerve, which run vertically. The course and anatomic variations of the IMA and inferior alveolar, lingual, auriculotemporal, and buccal nerves are shown. The distal IMA was quite tortuous and, when the artery straightened, we were able to perform a tension-free in situ IMA graft to the supraclinoid carotid artery in 9 of 12 specimens.

CONCLUSIONS

Knowledge of the anatomy of the ITF is a prerequisite for tumor resection in this area. The IMA may serve as a bypass graft to the supraclinoid internal carotid artery if the cavernous or petrous carotid artery is involved by tumor and needs to be sacrificed.

Infratemporal fossa surgery for malignant diseases

The improvement in the knowledge of the main anatomical landmarks permits an evolution in the safety of the surgical treatment and a conceptual development of the geometrical anatomico-surgical characteristics of the infratemporal fossa. This conceptual evolution determines surgical and oncological advantages: firstly, improved comprehension of the anatomico-surgical limits of the resection and secondly the safeguarding of the oncological "en-bloc" dissection. The lateral approach of the infratemporal fossa gives a wider exposure of the surgical field, a shorter depth of work, a good control over the vessels and the possibility of carry out a microsurgical transfer. The surgical approaches correspond to the topographical location and the biology of the neoplasm in cases with infratemporal fossa and inferior compartment location the lateral transfacial approach is indicated. In cases with involvement of the superior compartment a lateral transcraniofacial subtemporal approach is necessary in order to remove the skull base. In cases with a neoplastic invasion of the skull base where the dura mater is the anatomical plane free from disease it is necessary to utilize an intradural approach. In patients with a secondary spread into the inferior compartment from the maxilla a combined antero-lateral transfacial approach is indicated. Finally, an orbitomaxillary involvement with secondary spread in the upper compartment of the infratemporal fossa necessitates an antero-lateral transcraniofacial subtemporal subfrontal approach.

Transmandibular transpterygoid approach to the nasopharynx, parapharyngeal space, and skull base

The nasopharynx, upper part of the parapharyngeal space, and skull base are relatively inaccessible to the surgeon without major postoperative complications. Operative fields reached by conventional approaches through the palate and maxillary sinus are too limited and narrow to remove extensive tumors. The authors applied a transmandibular transpterygoid approach for the removal of five residual nasopharyngeal carcinomas (NPCs) after full doses of irradiation, one pleomorphic adenoma of the nasopharynx, and one large parapharyngeal schwannoma extending into the jugular foramen. This approach offers a wide operative field so that large blood vessels and cranial nerves can be managed easily. All tumors were successfully resected. Two patients with benign neoplasma had uneventful recoveries after treatment. Of five patients with NPC, two are alive with no evidence of disease for 68 months and 50 months, respectively, while two died of metastases to the liver and bones. The other patient is alive with metastases in the lungs. No tumor recurred in the local primary site, however. Since the number of NPC cases is small, the usefulness of surgical removal of the postirradiation residual NPC is not clear. Our experience proved that the transmandibular transpterygoid approach is a practical method in the treatment of neoplastic lesions in the nasopharynx, parapharyngeal space, and skull base.

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.

Infratemporal fossa and lateral skull base dissection: long-term results

In 1981, we described a new surgical technique featuring en bloc removal of infratemporal fossa malignancies. This approach offered a systematic resection of cancers in this region and was designated "stylohamular dissection" because the medial boundary of the bloc is surgical plane between the styloid process and the hamulus of the pterygoid. All structures lateral to this plane are removed, sparing the internal carotid artery. Since 1977, twenty infratemporal fossa and lateral skull base dissections have been performed for palliation of metastatic or recurrent disease in the infratemporal fossa. Most patients obtained palliation of trismus, facial pain, or relief from an unmanageable ulcerating lesion. This technique offers improved average disease-free intervals, as well as enhanced survival rates compared to non-en bloc resections. A summary of the case presentations, survival statistics, and surgical technique with detailed cadaver dissections are presented.

The surgical management of advanced malignancies of the parotid gland

Advanced malignancies of the parotid gland frequently invade the parapharyngeal space and the infratemporal fossa. The majority of these lesions have not been cured by surgery and/or radiotherapy, and palliation or cure can only be achieved by en bloc resection of this region. Stylohamular dissection is a systematic method for en bloc resection of the infratemporal fossa and lateral skull base. From January 1980 until December 1987, 18 patients with advanced parotid malignancies underwent stylohamular dissection. Pathologic examination revealed the following diagnosis: adenocarcinoma (7), squamous cell carcinoma (5), high-grade mucoepidermoid carcinoma (2), metastatic adenocarcinoma (1), fibrosarcoma (1), malignant hemangiopericytoma (1), and melanoma (1). Nine patients in this series are alive after a mean follow-up period of 3.5 years (range 1 to 9 years). Three patients are dead of uncontrolled local disease and three of distant metastasis. Three patients died of unrelated causes. All patients except the three who had uncontrolled disease experienced marked palliation from their pain, trismus, and unmanageable ulcerative lesions after surgery. The operative morbidity was relatively low.

Experience with the resection of parapharyngeal cancers via the infratemporal fossa approach

Between 1982 and 1984, a modified infratemporal fossa approach was used to resect cancers with extensive primary or secondary involvement of the infratemporal fossa and parapharynx in 10 patients. Nine patients exhibited persistent or recurrent disease of the upper aerodigestive tract and posterior cranial fossa following planned, curative-intent therapy; the remaining patient had a carcinoma ex-pleomorphic adenoma of the deep lobe of the parotid gland with a significant infratemporal fossa extension. Considered to have "unresectable" tumors, by traditional methods, 7 of the 10 patients underwent an en-bloc resection of their lesions with tumor-free margins. Tumor was present at the margins of the specimens in the other 3 patients. Two of the 10 patients died early in the postoperative period of medical complications. Another died 5 months postoperatively of a tumor-induced internal carotid artery rupture at the level of the foramen lacerum. A fourth patient died of his disease 6 months following his resection. One patient is alive, but has metastatic meningioma 2 years after surgery. The 5 remaining patients are without evidence of disease, with a mean follow up of 2 years. Indications for and refinements of the operative technique, particularly those related to the repair of such extensive ablative defects, are outlined on the basis of this early experience.

Surgeon's view of the skull base from the lateral approach

This paper presents the surgical anatomy of the skull base and infratemporal fossa. The information has been derived from the author's own experience in surgical and cadaver dissection, standard anatomical references, and selected experience of other skull base surgeons. Because the lateral approach has become the utilitarian method of exposure, the intricate detailed anatomy is demonstrated from this view at five levels of dissection, so the surgeon may gain a practical understanding of the surgical relationship of critical structures. Consistent anatomical landmarks can be used by the surgeon in the location of these critical structures. The styloid process, sphenoidal spine, and middle meningeal artery identify the internal carotid artery as it enters the carotid canal. The bony or fibrous septum that divides the jugular foramen into neural and vascular compartments may be used to better identify nerves IX, X, and XI. The zygomatic root is useful for location of the middle fossa dura. The lateral pterygoid plate leads directly to the foramen ovale. The increased precision of dissection permitted by use of the microscope requires an increased level of knowledge of anatomical structures in this area. It is hoped that the information presented in this paper will assist surgeons in the meticulous and thorough removal of skull base tumors and in the preservation of neural and vascular structures that are presently being sacrificed.