How I do it: combined petrosectomy.

BACKGROUND: Petroclival lesions are among the most complex to address in skull base surgery, being closely related to critical neurovascular structures and brainstem. The combined petrosectomy allows a wide exposure of large petroclival lesions with short working distance and provides multiple angles of attack, while limiting brain retraction. METHOD: We describe in a step-wise fashion the surgical steps of the combined petrosectomy. CONCLUSION: Combined petrosectomy with posterior transposition of the transverse-sigmoid sinus provides a wide surgical corridor to the ventral brainstem, middle and upper clivus, and infra-retrochiasmatic region.

Extra-intradural extracavernous subtemporal approach for chondrosarcomas: technical note and case report.

BACKGROUND: Skull base chondrosarcomas are rare tumors often invading the petrous apex and cavernous sinus, and many surgical approaches have been described. For most of them, these tumors grow slowly and their partial removal can be a first option before complementary radiotherapy. We described herein a minimally invasive approach that could be useful for soft non-calcified chondrosarcomas. METHOD AND RESULTS: We report a case of right parasellar chondrosarcoma, for which an extra-intradural extracavernous subtemporal approach allowed a safe effective partial removal. CONCLUSION: This surgical approach is indicated in selected cases to obtain good decompression or partial removal of lesions involving the parasellar space and the petrous apex.

Morphological and functional anatomy of the trigeminal triangular plexus as an anatomical entity: a systematic review.

PURPOSE: The sensory trigeminal nerve in the trigeminal cave of Meckel-which is an individualized lodge-is classically segmented into two parts: the trigeminal ganglion (TG) and the triangular plexus (TP). The TP has been defined as the portion of the trigeminal nerve from the posterior margin of the TG to the path over the upper ridge of the petrous bone. Due to its relatively unrecognized status, its morphological and functional anatomy has been reviewed by the authors through a PRISMA systematic review of the literature. METHODS: The authors have carried out a systematic review of the TP according to the PRISMA model with various bibliographical bases. Before 1947: Medic @ Library (BIU Santé Paris, 2017); Index-Catalog of the Library of the Surgeon-General's Office (US National Library of Medicine, 2017); Gallica (French National Library, 2017). After 1947: PUBMED, PubMed Central and MEDLINE. RESULTS: 56 articles were retained for full-text examination, of which 23 were chosen and included. The TP was described as having a triangular shape (30.2%), a plexual organization (97.4%) with sensory-, motor- and sympathetic-anastomoses (96.7%) that, however, respect the somatotopic trigeminal distribution (93.3%). The direct electrical stimulation of the root at the level of the TP (during radiofrequency-thermorhizotomy procedures) confirmed a clear-cut somatotopy. CONCLUSION: An understanding of both the morphological and the functional anatomy of the triangular plexus can contribute to accuracy and safety on the surgeries performed for trigeminal neuralgia and tumor removal inside the trigeminal cave.

Preoperative simulation of the running course of the abducens nerve in a large petroclival meningioma: a case report and literature review.

One of the most important and useful pieces of information in the preoperative evaluation of a large petroclival meningioma is the running course of the abducens nerve. The abducens nerve is small and has a long intracranial course, making it prone to compression by the tumor at various anatomical points. In relatively large tumors, it is difficult to confirm the entire course of the abducens nerve, even by heavy T2-thin slice imaging. We report a case of successful preoperative estimation of the course of the abducens nerve that aided in its complete preservation during the resection of a large petroclival tumor.

Combined petrosal approach for petroclival meningioma.

The authors present the case of a 56-year-old patient who presented with a large petroclival meningioma and clinical symptoms of brainstem compression and hydrocephalus. The authors describe a two-stage combined petrosal approach for complete resection of the tumor. The nuances of the approach and microsurgical technique are discussed, as well as the radiographic and clinical outcomes. The video can be found here: https://youtu.be/JxoTXS-uiHM .

Intradural anterior transpetrosal approach.

The standard anterior transpetrosal approach (ATPA) for petroclival lesions is fundamentally an epidural approach and has been practiced for many decades quite successfully. However, this approach has some disadvantages, such as epidural venous bleeding around foramen ovale. We describe here our experience with a modified technique for anterior petrosectomy via an intradural approach that overcomes these disadvantages. Five patients with petroclival lesions underwent surgery via the intradural ATPA. The intraoperative hallmarks are detailed, and surgical results are reported. Total removal of the lesions was achieved in two patients with petroclival meningioma and two patients with pontine cavernoma, whereas subtotal removal was achieved in one patient with petroclival meningioma without significant morbidity. No patient experienced cerebrospinal fluid leakage. The intradural approach is allowed to tailor the extent of anterior petrosectomy to the individually required exposure, and the surgical procedure appeared to be more straightforward than via the epidural route. Caveats encountered with the approach were the temporal basal veins that could be spared as well as identification of the petrous apex due to the lack of familial epidural landmarks. The risk of injury to the temporal bridging veins is higher in this approach than in the epidural approach. Intradural approach is recommended in patients with a large epidural venous route, such as sphenobasal and sphenopetrosal vein. Navigation via bone-window computed tomography is useful to identify the petrous apex.

Subtotal petrosectomy and Codacs™: new possibilities in ears with chronic infection.

Subtotal petrosectomy combined with obliteration of the tympanomastoid is a standard procedure to treat temporal bones in patients with radical cavity and chronic infections. Currently, patients with profound-to-severe sensorineural hearing loss are often fitted with cochlear implants. In the case of profound mixed hearing loss, active middle ear implants have been used successfully. The new Codacs™ system provides an effective treatment for patients with severe-to-profound mixed hearing loss; however, only aerated middle ears have been treated with this device. The question arises whether the Codacs™ can be implanted in patients with radical cavity or ears with chronic otorrhea. Of the 41 patients who were implanted with the Codacs™ at the department, 4 received the device after subtotal petrosectomy and obliteration with abdominal fat. Clinical and audiological results were assessed. The device was implanted without any complications in the obliterated subtotal petrosectomy. The preliminary results of the first two patients showed stable bone conduction thresholds and indicated improved speech intelligibility in quiet and noise. Implanting the Codacs™ device after subtotal petrosectomy and obliteration with abdominal fat has been proven to be a feasible and suitable procedure for patients with radical cavity or chronic otorrhea. The speech intelligibility outcome directly after activation was comparable to patients with aerated middle ears.

Petroclival meningiomas: an update on surgical approaches, decision making, and treatment results.

OBJECT: Petroclival meningiomas remain a formidable challenge for neurosurgeons because of their location deep within the skull base and proximity to eloquent neurovascular structures. Various skull base approaches have been used in their treatment, and deciding which is the optimal one remains controversial. Attempts at achieving gross- or near-total resections are associated with an increased rate of morbidity and mortality. As adjunctive treatment options such as stereotactic radiosurgery have been developed and become widely available, there has been a trend toward accepting subtotal resections in an effort to minimize neurological morbidity. This paper reviews a recent series of patients with petroclival meningiomas and highlights current management trends and important considerations useful in surgical decision making. METHODS: The records of patients with large (> 3 cm) petroclival meningiomas surgically treated by the senior author over the past 5 years were reviewed. The clinical results are presented as examples of the surgical approaches available for approaching these tumors, and treatment options are reviewed. RESULTS: Of 196 meningiomas surgically treated during the study period, 8 lesions in 8 patients met the study criteria. Overall clinical results were excellent, with no death or major morbidity. Intracranial gross- or near-total resection (Simpson Grade 1, 2, or 3) was achieved in 5 patients (67%). New cranial nerve deficits occurred in 3 patients (37%) and were more common in patients in whom a subtotal resection was performed (2 of 3 cases). A variety of surgical approaches were used. Important considerations determining the best approach include the location of the tumor relative to the internal auditory canal, the presence of preoperative hearing loss, and the location of the tumor relative to the tentorium. CONCLUSIONS: Achieving gross- or near-total resections of large petroclival meningiomas remains achievable and should be the primary goal of surgical treatment. A retrosigmoid craniotomy remains a workhorse surgical approach for most petroclival tumors of any size. Tumors that are medial to the internal auditory canal and span both middle and posterior cranial fossae are often best treated with a combined transpetrosal approach, which is especially true if there is a preoperative hearing deficit.

Chondrosarcoma of the petrous apex with nerve abducens involvement in a woman with pre-existing contralateral amblyopia.

We report about a case of a woman in her 50s with a chondrosarcoma of the petrous apex. She has a strabism due to a right-sided amblyopia since childhood and noticed a slowly progressive squint angle in the last months. Her general practitioner (GP) referred her to an ophthalmologist who diagnosed a left abducens paresis and initiated an MRI demonstrating a mass in the left petrous apex. A transnasal endoscopic transsphenoidal biopsy revealed a grade I chondrosarcoma. The patient underwent an endoscopic transsphenoidal anterior petrosectomy approach with complete removal of the tumour. After surgery the squint angle gradually improved to previous levels, so that the patient was able to resume her work. This report demonstrates that even slight changes of a squint angle without diplopia, in this case because of pre-existing amblyopia, could be a hallmark of an intracranial process.

Two-bone flap craniotomy for the transpetrosal-presigmoid approach to avoid a bony defect in the periauricular area after surgery on petroclival lesions: technical note.

The authors describe a two-bone-flap craniotomy technique to avoid the bone defect caused by the transpetrosal-presigmoid approach. Briefly, this technique includes three steps. The first step is to elevate a temporoparietal bone flap located superiorly to the transverse and sigmoid sinuses. The second step is to dissect the transverse and sigmoid sinuses away from the bone by inserting a gelatin sponge. This maneuver provides hemostasis and protects the sinuses from injury. The third step is to cut a second bone flap including part of the temporal bone and the outer table of the mastoid bone with a high-speed drill system. After the operation, the two bone flaps are fixed in place with titanium osteosynthesis fixation material. This approach provides a simple, easy, and safe technique for the transpetrosal-presigmoid approach. The technique has been performed in 83 patients treated for petroclival neoplasms with excellent cosmetic results.

Rapid Recovery of Cranial Nerve Deficits After Anterior Petrosal (Kawase) Approach for Medically Refractory Petrous Apicitis.

BACKGROUND: The mainstay treatment for petrous apicitis (Gradenigo's syndrome) is medical management with antibiotics, steroids, and placement of pressure equalization tubes. The role for surgery is limited as second-line treatment if conservative methods have failed. CASE DESCRIPTION: We report 2 cases of medically refractory petrous apicitis presenting with progressive cranial neuropathies who underwent petrous apex resection and debridement via an anterior petrosal (Kawase) approach. Both patients had improvement of their preoperative cranial nerve deficits within 24-48 hours of surgery, that previously did not improve after 2 weeks of medical management. CONCLUSIONS: To our knowledge, the use of the Kawase approach for petrous apicitis has not been previously reported. In addition, we postulate that surgical intervention can potentially result in quicker recovery of preexisting cranial nerve deficits in medically refractory petrous apicitis. This raises the potential role of earlier surgical intervention.

Endoscopic radial artery harvesting for U-clip EC-IC bypass in the treatment of a giant petrous internal carotid artery aneurysm: technical case report.

INTRODUCTION: High-flow extracranial-intracranial (EC-IC) bypass and aneurysm trapping constitutes a well-known surgical solution for internal carotid artery (ICA) aneurysms that are not amenable to clip ligation or endovascular therapy. The advantages of the radial artery (RA) as a conduit for myocardial revascularization have become widely accepted, with a better patency rate than that of the saphenous vein. CASE REPORT: A 66-year-old woman was found to harbour a right giant, partially thrombosed aneurysm of the intrapetrous segment of the internal carotid artery. Endoscopic harvesting of the RA was achieved combining a resterilizable retractor and a vessel sealing system. After neck dissection, the main trunk of the middle cerebral artery (MCA), its branches, and part of the aneurysm were isolated through a right fronto-orbito-zygomatic craniotomy. The external carotid artery, distal to the origin of the facial artery, was chosen in the neck for an end-to-end microanastomosis. The temporal branch of the MCA was selected for an end-to-side microanastomosis with the radial graft using ten U-clips. The total temporary occlusion time was 13 min. The post-operative course was uneventful. CONCLUSION: Endoscopic technique provides improved patient satisfaction, especially in terms of length of the surgical incision, when compared to the conventional approach. Combined with the innovative use of U-clips, this case illustrates how new technologies can simplify ECA-ICA bypass surgery while yielding a better cosmetic and functional outcome.

The classification of posterior petrous meningiomas and its clinical significance.

This retrospective analysis of the clinical records of 42 patients was used to study the clinical significance of a classification system for posterior petrous meningiomas. According to clinical manifestations and radiological images, posterior petrous meningiomas were classified into three types: type I (cerebella type; 12 patients), tumours involved and compressed the cerebellum; type II (cranial nerve type; 16 patients), tumours involved the cranial nerves; and type III (combined type; 14 patients), tumours involved more than one structure such as the cerebellum, cranial nerves and the brain stem. All patients underwent microneurosurgery and the total resection rate was 90%. It was more difficult totally to resect type II and III tumours than type I tumours and the post-operative functional outcomes were worse. Microneurosurgical techniques and skills are critical to increase the total resection rate of posterior petrous meningiomas in order to decrease the mortality and disability rates.

Trigeminal Neuralgia Due to Petrosal Bone Deformity.

BACKGROUND: There have been a few previous reports of trigeminal neuralgia caused by bony structures. We report a rare case of trigeminal neuralgia caused by petrous bone deformity. CASE DESCRIPTION: A-43-year-old man with facial pain in the left maxillary and mandibular divisions of the trigeminal nerve was referred to our hospital. Computed tomography showed bone hyperplasia protruding into the left cerebellopontine cistern, compressing the left trigeminal nerve. Administration of carbamazepine ameliorated facial pain, but the effect was unsatisfactory, and microvascular decompression was performed through the anterior transpetrosal approach. The protruding petrous bone was drilled out to release compression of the trigeminal nerve, thus straightening the deviated trajectory of the nerve. The superior cerebellar artery adjacent to the thickened petrosal bone seemed to have compressed the trigeminal nerve and was also transposed. The facial pain disappeared completely after microvascular decompression surgery. CONCLUSIONS: The anterior transpetrosal approach is an appropriate and essential strategy for trigeminal neuralgia caused by petrous bone deformity of the petrous apex.

Insidious onset of headache, diplopia and Horner's syndrome: a rare case of petrous bone osteomyelitis.

We present an unusual case of skull base osteomyelitis in an 88-year-old woman. She presented with gradual onset unilateral headache and diplopia. On examination, there was evidence of a left-sided Horner's and ipsilateral sixth nerve palsy. In addition to persistent raised inflammatory markers, an MRI neck identified signal change in the petrous bone confirming a diagnosis of skull base osteomyelitis. Skull base osteomyelitis should be considered in presentations of subacute raised inflammatory markers in the context of ipsilateral cranial nerve signs.

Cholesterol Granulomas: A Comparative Meta-Analysis of Endonasal Endoscopic versus Open Approaches to the Petrous Apex.

Petrous apex cholesterol granulomas (PACG) are rare disorders that can lead to patient morbidity and must, occasionally, be drained by either endoscopic endonasal (EN) or open procedures (OP). The objective of our study was to complete a review of the literature to compare the EN and OP approaches on multiple levels, notably on safety and effectiveness. Ovid MEDLINE and Embase were used to perform a thorough literature review of all cases of PACG treated by either EN or OP dating from January 1948 to August 2017. In total, 49 articles were selected including 23 for EN (n=76) and 26 for OP (n=210). Differences were found in the incidence of preoperative hearing loss (HL) (EN 18.4%, OP 57.3%; p<0.001), headache (EN 48.7%, OP 31.2%; p=0.007), and disequilibrium (EN: 14.5%, OP 26.1%; p=0.04). Differences in lesion proximity to the sphenoid sinus (EN 23.6%, OP: 1.0%; p<0.001), clivus (EN 11.8%, OP 4.7%; p=0.03), otic capsule (EN 0.0%, OP 5.2%; p=0.03), internal auditory canal (EN 2.6%, OP 10.9%; p=0.01), and internal carotid artery (ICA) (EN 9.2%, OP 2.8%; p=0.02) were found on preoperative imaging. The EN procedure had better hearing improvement rates (EN 85.7%, OP 23.4%; p<0.001), lower complication rates (EN 7.9%, OP 17.6%; p=0.04), shorter median follow-up (EN:13.5 months, OP:37.2 months; p<0.001), and shorter time to recurrence (EN 3 months, OP 22.6 months; p=0.002) than the known OP. No differences were found in age, preoperative size, recurrence rate, operative time, stent placement, or improvement of other symptoms. Endoscopic nasal approaches, when feasible, should be favored to open procedures for PACG drainage given their better hearing improvement and less complication rates.

Intralabyrinthine sporadic endolymphatic sac tumour.

INTRODUCTION: Endolymphatic sac tumours are benign, slowly growing tumours that invade the temporal bone, and present clinically in the form of unilateral hearing loss. They can be sporadic or occur in the context of Von Hippel-Lindau disease (VHL). CASE SUMMARY: The authors report a case of endolymphatic sac tumour arising in the utricle presenting histological and immunohistochemical features corresponding to endolymphatic sac tumour in a patient without VHL. DISCUSSION: Endolymphatic sac tumours invade the posterior part of the petrous temporal bone. According to two studies concerning patients with Von Hippel-Lindau disease, endolymphatic sac tumours arise from the endolymphatic duct. This case of intralabyrinthine sporadic endolymphatic sac tumour supports this hypothesis for sporadic forms, indicating the need for labyrinthectomy associated with tumour resection to avoid recurrence.

[Isolated apical petrositis: an atypical case of Gradenigo's syndrome]. / Isolierte apikale Petrositis: Ein atypisches Gradenigo-Syndrom.

In 1904 Guiseppe Gradenigo described an infection of the apex of the petrous part of the temporal bone from acute otitis media with the clinical symptoms of unilateral pain around the eye, diplopia due to sixth nerve paralysis and persistant otorrhea. While this infection became evident by inward extension from petrositis in the majority of fatal cases from acute otitis media in the preantibiotic era, it has now become very rare. Today, cases mainly derive from cholesteatomas or chronic osteomyelitis of the petrous bone. However, due to intense antibiotic treatment in acute otitis media clinical signs of petrositis may be less typical compared to former times. We report on a 12-year-old boy with rapid onset of sixth nerve paralysis without clinical signs of acute otitis media or mastoiditis. CT and NMR imaging confirmed infection of the petrous apex. He was treated by mastoidectomy with exploration of a posterior cell group from the epitympanon around the semicircular canals and subsequent high dose intravenous antibiotics. The patient recovered without any loss of inner ear or facial nerve function. The paralysis of the sixth nerve disappeared completely within 6 weeks.

[Primary cholesteatoma of the middle ear and petrosal bone]. / Perlak pierwotny ucha srodkowego i szczytu piramidy.

Petrosal cholesteatomas are rare lesions, which may be primary or acquired in nature. We report a case of primary cholesteatoma in petrous bone occurring in 51-year old woman who presented with a unilateral facial nerve palsy and conductive hearing loss, despite normal tympanic membrane appearance. Early diagnosis was facilitated by computed tomography scanning and magnetic resonance imaging. Complete cholesteatoma removal was accomplished using a transtemporal supralabyrinthine approach, which allowed hearing preservation. Facial nerve function is the main complication of these lesion. We suggest that use of CT scanning and MRI in unilateral conductive hearing loss may allow the earlier detection of the most cases of petrosal cholesteatomas.