Comparison of endoscopic multiport approaches to the petrous apex: contralateral transmaxillary versus contralateral medial transorbital corridor.

OBJECTIVE: Accessing the petrous apex (PA) via an endoscopic endonasal approach (EEA) is challenging due to its posterior and lateral anatomical relationship with the paraclival carotid artery. Typically, the EEA requires the mobilization or compression of the vessel and the use of angled-lens endoscopes and instruments. A sublabial contralateral transmaxillary (CTM) corridor has been used to overcome these challenges. Still, it requires extensive osteo-meatal disruption and drilling of the medial pterygoid process, which risks the vidian nerve and increases nasal morbidity. Furthermore, the CTM corridor positions the endoscope in the same horizontal plane as the instruments passing through the nostrils, leading to fencing. The authors propose a novel minimally invasive route to the PA, the precaruncular contralateral medial transorbital (cMTO) corridor, to address these issues. This anatomical study compares the EEA+CTM and EEA+cMTO corridors in accessing the PA. METHODS: The authors dissected 14 fresh, preinjected cadaveric specimens (28 sides) using neuronavigation to complete EEA, cMTO, and CTM on each side. In addition to qualitative analysis, they measured and compared the working distance between the entry point (nose, orbit, maxilla) and the petrosal process of the sphenoid bone (PPSB), superomedial PA, and foramen lacerum (FL); angle of attack (AoA); area of surgical freedom; endoscope-instrument fencing angle; and visual angle for each approach. RESULTS: The cMTO corridor provided the shortest working distance to the petroclival region (PA = 67.4 ± 4.47 mm, PPSB = 67.57 ± 4.33 mm, and FL = 66.30 ± 4.77 mm) compared to the CTM (PA = 75.85 ± 3.63 mm, PPSB = 76 ± 3.96 mm, and FL = 74.52 ± 4.26 mm) and to the EEA (PA = 85.16 ± 3.16 mm, PPSB = 84.55 ± 3.02 mm, and FL = 83.42 ± 3.21 mm, p < 0.001). Both CTM and cMTO corridors had a similar visual angle to the PA (20.72° ± 2.16° and 21.63° ± 1.84°, respectively), offering a similar but significantly better visualization than EEA alone (44.71° ± 3.24°, p < 0.001). The cMTO corridor provided better instrument maneuverability than the CTM, as evidenced by a significantly greater fencing angle (30.9° ± 4.9°) than with the CTM (21.7° ± 4.02°, p < 0.001). The vertical AoAs for the EEA, cMTO, and CTM corridors were 9.79° ± 1.75°, 10.65° ± 0.82°, and 9.82° ± 1.43°, respectively (p = 0.009), whereas in the horizontal plane, these were 9.29° ± 1.51°, 9.10° ± 0.73°, and 10.49° ± 1.43° (p < 0.001), respectively. Both the CTM and cMTO corridors offered similar areas of surgical freedom (678.06 ± 99.5 mm2 and 673.59 ± 104.8 mm2, p = 0.986), but they were more significant than that provided by the EEA 487.29 ± 112.9 mm2 (p < 0.001). CONCLUSIONS: The EEA+cMTO multiport technique may be a better alternative than the EEA+CTM multiport approach for targeting the petroclival region. However, clinical validation is required to confirm these laboratory findings.

Anatomical and Radiological Analysis of Structures of Petrous Part of the Temporal Bone and Their Impact on Area of Anterior Petrosectomy.

BACKGROUND: Anterior petrosectomy (AP) is a commonly recognized approach for accessing tumors located in the petrous apex region. The essence of AP lies in drilling the petrous part of the temporal bone within the Kawase quadrangle. In our study, we conducted radiological and anatomical analyses of the structures within the petrous portion of the temporal bone, evaluating their impact on the surgical field during AP. METHODS: We conducted an analysis of 15 anatomical specimens and 20 3D reconstructions based on computed tomography scans of the middle ear. The analyzed structures included the impression of the trigeminal nerve, the groove of the greater petrosal nerve, the arcuate eminence, and the angle between eminentia arcuata and grove for greater petrosal nerve. RESULTS: The mean surface area measured by radiological methods does not deviate significantly from the mean surface area measured by anatomical methods 276.265mm2 (interquartile range: 217.603-309.188) versus 233.21mm2 (interquartile range: 210.923-255.453) P = 0.051. We established a threshold 195,99mm2 for radiological determination of the surface area at which another approach should be considered. Additionally, we have developed corrections for specific radiological factors to enable a better assessment of anatomical conditions. CONCLUSIONS: Our results indicate that preoperative assessment of anatomical conditions based on 3D reconstructions of computed tomography of the middle ear can be a valuable tool in preoperative planning of surgery on tumors in the petroclival region using the AP. Further studies involving a larger sample size are necessary to validate the findings of our study.

Endoscopic transorbital approach to the petrous apex: is orbital rim removal worthwhile for the exposure? An anatomical study with illustrative case.

OBJECTIVE: The endoscopic transorbital approach (ETOA) has been demonstrated to be a feasible ventral route to the petrous apex. Yet, it has been pointed to as a deep and narrow corridor for anterior petrosectomy; particularly, medialization of the instruments can become an issue when targeting the petroclival area. To overcome this limitation, an ETOA with orbital rim removal (ETOA-OR) has been suggested, but not de facto compared, with a transorbital approach without removal of the rim. This addition could augment the surgical exposure and freedom of movement when accessing the petrous apex area. METHODS: Five human cadaveric heads (10 sides) were dissected. First, anterior petrosectomy was performed via a conventional ETOA (without orbital rim removal). Second, en bloc removal of the orbital rim was performed, with enlargement of the orbital craniectomy and, subsequently, further drilling of the medial petrous apex. Qualitative and quantitative comparisons are provided. An illustrative surgical case is also shown. RESULTS: The transorbital route allowed the authors to perform an anterior petrosectomy in all specimens. The landmarks of bone removal are superposed onto those in the transcranial route. The ETOA-OR increased the volume of craniectomy (from 4.0 mL to 5.5 mL), the lateromedial angulation, and superoinferior angulation of the instruments within the petrous area. Thus, this approach improved the exposure of the medial petroclival area, allowing for an augmented petrosectomy (from 1.4 mL to 2.0 mL, 39.5% increase) and for increased maneuverability, both in the petrous area (from 44.1 cm2 to 76.5 cm2, 73.3% increase) and in the posterior fossa (from 20.2 cm2 to 52.0 cm2, 158% increase). The ETOA-OR was also pragmatically applied to treat a recurrent petroclival meningioma. Complete removal was achieved, the abducens nerve palsy improved, and the trigeminal neuralgia decreased in severity, yet still required medication. CONCLUSIONS: The authors provide the first formal anatomical comparison between the transorbital approach with preservation of the orbital rim and a transorbital approach with removal of the rim to access the petrous apex. In addition, an illustrative case is used as a proof of concept and feasibility. According to the authors' data, the ETOA-OR significantly improves surgical exposure and the surgeon's comfort in this deep region. The bony defect can be reconstructed to avoid cosmetic deformities, maintaining the minimally disruptive concept of transorbital surgery.

Management of Petrous Bone Cholesteatoma: The Gruppo Otologico Experience.

BACKGROUND: The term petrous bone cholesteatoma (PBC) refers to lesions extending deep to the bony labyrinth via superior, inferior, and posterior cell tracts. PBC is a rare incidence accounting for only 4-9% of petrous bone lesions. Lesions of petrous bone represent a real surgical challenge due to its complex relationship with critical neurovascular structures. OBJECTIVE: To demonstrate our 40-plus years' experience in the management of PBC, depict the clinical features of PBC according to Sanna's Classification, evaluate the postoperative follow-up of surgically treated PBC patients, and determine the recurrence rate. STUDY DESIGN: Retrospective medical record review. MATERIAL AND METHODS: Medical records of 298 PBC cases operated from the year 1983 to 2024 were thoroughly evaluated. RESULTS: A total of 298 PBC cases were surgically treated at our center. The average age at presentation in this series was 47 years. Males are more affected than females with a male-to-female ratio of 2.2:1. The most common presenting symptoms were hearing loss (84%), tinnitus (48%), and facial nerve paralysis (45%). Mixed hearing loss (41%) was the commonest audiometric pattern of hearing loss followed by conductive hearing loss (26%) and profound sensorineural hearing loss (4%) and a total of 86 (29%) had anacusis at presentation. On preoperative facial nerve function examination, 133(45%) of patients had various degrees of paresis and complete paralysis whereas 55% had normal HB-I function. The commonest degree of paresis noted was HB-III (18%) followed by HB-VI (5%). A total of 150 (50%) patients had previous otologic surgery and two-thirds of these cases had two or more prior otologic surgeries. According to Sanna's PBC Classification system, we identified that the supralabyrinthine class (44%) is the commonest of all classes followed by massive (33%), infralabyrinthine-apical (9%), infralabyrinthine(8%), and apical (5%) classes in that order. However, only ten patients had congenital type of PBC. Extension to clivus, sphenoid, nasopharynx, intradural space, and occipital condyle was found in 8, 2, 1, and 2 cases respectively. The most commonly used surgical approaches at our center were TO, MTCA with rerouting of the facial nerve, and TLAB with external auditory canal (EAC) closure. Postoperative complications were minimal and the duration of follow-up ranged from one to 458 months with a mean duration of 65 months. Residual lesions were evident in 11 cases (3.7%), with the surgical cavity, middle and posterior fossa dura, and jugular bulb being the commonest sites. CONCLUSION: Petrous bone cholesteatoma represents diagnostically and surgically challenging lesions of temporal bone which are usually frustrating to the treating surgeon. A high index of clinical suspicion, thorough clinical evaluation examination, and preoperative radiologic evaluation make the diagnosis easier. Preoperative anatomic classification of the lesion enables the physician to choose the appropriate surgical approach. Sanna's classification is widely used to classify PBC in relation to the labyrinthine block. Radical disease removal should always come before hearing preservation. Cavity obliteration is the solution to the problems related to a large cavity. Finally, advancements in lateral skull base approaches create adequate surgical access for the complete removal of the lesion with excellent control of critical neurovascular structures.

The trans-sylvian trans-petrosal "half & half" approach-a how I do it.

BACKGROUND: Petroclival meningiomas are one of the most challenging tumors to be operated in the realm of neurosurgery. Many approaches have been developed over the years. METHOD: The authors describe the Half & Half (H&H) approach whose main indication is petroclival meningiomas with suprasellar extension. The part of the tumor located above CN III and in the retrochiasmatic space is addressed through a trans-sylvian, while the petroclival portion is through an extradural anterior petrosectomy approach. The wide surgical corridor given by this approach allows extensive tumor resection while avoiding the risk associated with the manipulation of intracavernous neurovascular structures. CONCLUSION: The H&H approach is an effective strategy to maximize the safe resection of petroclival meningiomas.

Pneumatocoele after cochlear implantation with lateral petrosectomy: A minor complication?

OBJECTIVE: To illustrate the clinical features and management of pneumatocoele presenting with a trap-valve mechanism after cochlear implantation with lateral petrosectomy (LP) in comparison with literature. INTRODUCTION: Pneumatocoele is a rare complication of cochlear implant (CI) surgery, generally managed with conservative treatments. METHODS: We describe a progressively increasing pneumatocoele with a trap-valve mechanism occurring one year after CI with LP, successfully managed with revision surgery. Literature review was performed on this topic. RESULTS: Our case was the second ever reported in literature. It appeared consequently to forceful nose-blowing in a patient with refractory nasal polyposis. Unlike the pneumatocoeles reported after standard CI, we advised revision surgery as well as in the case of pneumatocoele after staged LP and CI. In both the patients subcutaneous air collection occurred as a late complication and an insufficient Eustachian tube closure was disclosed, which is considered a complication of LP itself. Surgical management was necessary in consideration of the risk of ascending infections associated with Eustachian tube patency in LP with CI. CONCLUSION: We consider surgical treatment mandatory in pneumatocoele after CI with LP, it is indeed the sentinel of the restoration of Eustachian tube patency and the potential prelude to major complications.

A Modified Anterior Petrosectomy Approach for Resection of Petroclival Meningioma; with Management of Complications.

Due to deep location and for being adjacent to neurovascular structures, petroclival meningiomas (PCMs) are generally considered to be associated with a high rate of recurrence and cranial nerve deficits.1 This video presents a 49-year-old female patient reporting right trigeminal neuralgia for more than 1 year. The incidence of this symptom with PCMs is about 5%.2 According to the classification system proposed by Kawase et al.3 and Ichimura et al.,4 this is a tentorium type PCM. A modified anterior petrosectomy approach was adopted based on the tumor size and its origin. The case presentation, surgical technique, postoperative outcome are reviewed. The treatments to the intraoperative trochlear nerve injury and temporal bridging vein occlusion are displayed (Video 1). The patient gave verbal consent for participating in the procedure and surgical video.

Subtotal Petrosectomy: Pictorial Review of Clinical Indications and Surgical Approach.

Subtotal petrosectomy (STP) is characterized by obliteration of the middle ear and occlusion of the external auditory canal. The advent of the endoscope has allowed a reduction in morbidity for some conditions such as cholesteatoma and other middle ear disorders, but STP still plays an important role. A retrospective review of medical records and videos of patients who had undergone STP was performed. Perioperative data and images were collected from various clinical cases who had undergone subtotal petrosectomy at our tertiary referral university hospital in Verona. We confronted our experience with a review of the literature to present the main indications for this type of procedure. STP allows a variety of diseases to be managed effectively as it offers the possibility of a definitive healing with radical clearance of temporal bone. Moreover, it can be safely combined with other procedures with a very low complication rate. Although the endoscope represents a revolution in ear surgery, STP, when indicated, is nowadays a surgical option that should be included in the otosurgeon's portfolio.

Renewed Concept of Mastoid Cavity Obliteration with the Use of Temporoparietal Fascial Flap Injected by Injectable Platelet-Rich Fibrin after Subtotal Petrosectomy for Cochlear Implant Patients.

Background: The subtotal petrosectomy procedure may be useful for cochlear implantation in selected patient groups. Although it is highly effective, complications can arise, which may have economic implications for the patient due to the high cost of the device. Therefore, several authors have attempted to identify the most effective concept for obliteration. Methods: We present a pilot descriptive study of application techniques for obliterating cavities after subtotal petrosectomy using a temporoparietal fascial flap (TPFF) modified with injectable platelet-rich fibrin (IPRF+) for three cochlear implant (CI) patients. Results: Our concept preserves important anatomical structures, such as the temporalis muscle, which covers the CI receiver-stimulator. Injection of IPRF+ also increases the available tissue volume for obliteration and enhances its anti-inflammatory and regenerative potential. Conclusions: To the best of our knowledge, the use of TPFF for filling the cavity has not been adopted for CI with SP and for blind sac closure. Our literature review and our experience with this small group of patients suggest that this procedure, when combined with IPRF+ injections, may reduce the risk of potential infection in the obliterated cavity, particularly when used with CI. This technique is applicable only in cases when the surgeons are convinced that the middle ear cavity is purged of cholesteatoma.

Mandibular Fossa Approach to Petroclival and Anterior Pontine Lesions.

Objective To describe the anatomy related to a novel approach to the petroclival region through the mandibular fossa for the treatment of petroclival and anterior pontine lesions. Design Five dry skulls were examined for surgical approach. Three adult cadaveric heads underwent bilateral dissection. One cadaveric head was evaluated with computed tomography after dissection. Setting This study was performed in an academic medical center. Participants Neurosurgical anatomy researchers performed this study using dry skulls and cadaveric heads. Main Outcome Measurements This was a proof-of-concept anatomical study. Results The mandibular fossa approach uses a vertical preauricular incision above the facial nerve branches. Removal of the temporomandibular joint exposes the mandibular fossa. The anterior boundary is the mandibular nerve at the foramen ovale, and the posterior boundary is the jugular foramen. The chorda tympani, eustachian tube, and tensor tympani muscle are sectioned. The carotid artery is transposed out of the petrous canal, and a petrosectomy is performed from Meckel's cave to the foramen magnum and anterior occipital condyle. Dural opening exposes the anterior pons, vertebrobasilar junction, bilateral vertebral arteries, and the ipsilateral anterior and posterior inferior cerebellar arteries. At completion, the temporomandibular joint is reconstructed with a prosthetic joint utilizing a second incision along the mandible. Conclusions The mandibular fossa approach is a new trajectory to the petroclival region and the anterior pons. It combines the more anterior angle of endoscopic approaches along with the enhanced control of open approaches. Further study is necessary before this approach is used clinically.

The complete anterior petrosectomy: an expanded extended-middle fossa approach with removal of the infratrigeminal petrous apex and drilling of the lateral clivus.

Intradural exposure in the extended middle fossa anterior transpetrosal approach is traditionally limited to the inferior petrosal sinus inferomedially. Expanding bone removal of the petrous apex around the petrous internal carotid artery (ICA), underneath the trigeminal ganglion/mandibular nerve, and into the lateral component of the clivus can significantly expand the limits of this approach beyond the inferior petrosal sinus and allows for exposure of the midline structures, aspects of the contralateral inferior clival region, and, when high riding, the vertebrobasilar junction. To date, no descriptive techniques for drilling into the lateral clivus in this approach have been published. The authors provide a detailed stepwise description of their complete anterior petrosectomy, in use at their institution, that involves skeletonization of the posteromedial petrous ICA, gentle elevation of the trigeminal ganglion/mandibular nerve, removal of the infratrigeminal petrous apex, and two techniques for drilling into the lateral clivus along the petroclival fissure. These techniques provide a direct and unobstructed corridor to the midpetroclival region and ventral brainstem with greater maneuverability and enhanced control of the midline structures, which is especially useful for resection of petroclival meningiomas, chondrosarcomas, and giant vascular lesions of the mid- and upper basilar artery and its proximal branches.

Acquired cholesteatoma after cochlear implants: case series and literature review.

PURPOSE: To assess the prevalence and management of acquired cholesteatoma after cochlear implantation in pediatric and adult patients. METHODS: Retrospective case review of pediatric and adult cochlear implants (CI) followed at a tertiary referral center and literature review of acquired cholesteatoma after CI surgery, to identify its prevalence, cause, and treatment. RESULTS: Nine pediatric CIs were diagnosed with cholesteatoma in seven patients after 6.4 ± 4 years from CI surgery, and two adults after 11.3 and 21.7 years from CI surgery. Thirty-four pediatric cases and 26 adult cases are described in the literature. Cholesteatoma has a prevalence of 0.54% in pediatric CIs, and 1.79% in adult CIs (case series and literature). Adult cases were diagnosed significantly later compared to pediatric cases (Mann-Whitney test, p = 0.0460). Three pediatric cholesteatomas were treated with conservative surgery and preservation of the CI; they all developed recurrent disease. The remaining pediatric cases underwent subtotal petrosectomy with simultaneous CI explantation and staged reimplantation. Only one case recurred. The adult cases underwent simultaneous subtotal petrosectomy, explantation, and reimplantation. Similarly, 33.3% of cases treated with conservative/reconstructive surgery in the literature required revision surgery or conversion to subtotal petrosectomy against 6.2% of subtotal petrosectomies in the literature. CONCLUSIONS: Cholesteatoma after CI is a rare and late-onset complication of CIs. It is more prevalent in the adult CI population, although it affects children significantly earlier. The treatment of choice is subtotal petrosectomy and CI explantation with simultaneous or staged reimplantation.

Intralabyrinthine schwannoma: Surgical management and cochlear lumen preservation.

The present video reports the surgical removal of an intralabyrinthine schwannoma. The video contains patient's medical history, preoperative radiological evaluations and detailed description of surgical steps of the procedure, consisting in labyrinthectomy, cochleostomy and insertion of a dummy electrode in the preserved cochlear lumen within the context of a subtotal petrosectomy.

Neurosurgical Intervention in the Treatment of Gradenigo Syndrome: A Case Report.

Gradenigo syndrome comprises a clinical triad: retro-orbital pain, sixth cranial nerve palsy, and purulent otorrhea. This clinical syndrome often arises secondary to petrous apicitis, which is an infection of the petrous apex that may result from the contiguous spread of infection from the ear or mastoid. This syndrome is very rare, and based on the existing literature, the initial approach for treatment involves long-term administration of IV antibiotics, which may resolve the underlying infection related to petrous apicitis, mastoiditis, and/or otitis media. In this case, the patient, a 69-year-old male, had a progression of several symptoms, including recurrent headaches, diplopia, hearing loss, and dysphagia, despite long-term antibiotic therapy and a prior mastoidectomy. Thus, the neurosurgical team decided to intervene via anterior petrous bone resection via the Kawase approach, which unfortunately did not result in the resolution of the patient's symptoms. The patient continued to have symptoms of Gradenigo syndrome, including sixth cranial nerve palsy and was subsequently referred to outpatient follow-up for further management. In this report, we present the patient's case and a brief review of the literature concerning various treatment modalities for Gradenigo syndrome.

Current trends on subtotal petrosectomy with cochlear implantation in recalcitrant chronic middle ear disorders.

Objective: To establish the safety and effectiveness of subtotal petrosectomy with cochlear implantation in patients affected by chronic middle ear disorders to refractory to previous surgical treatments. Methods: A multicentre, retrospective study was conducted on patients affected by recalcitrant chronic middle ear disorders who underwent cochlear implantation in combination with subtotal petrosectomy. Patients' details were collected from databases of 11 Italian tertiary referral centres. Additionally, a review of the most updated literature was carried out. Results: 55 patients were included with a mean follow-up time of 44 months. Cholesteatoma was the most common middle ear recurrent pathology and 50.9% of patients had an open cavity. 80% of patients underwent a single stage surgery. One case of explantation for device failure was reported among the 7 patients with post-operative complications. Conclusions: Subtotal petrosectomy with cochlear implantation is a benchmark for management of patients with recalcitrant chronic middle ear disorders. A single stage procedure is the most recommended strategy. Optimal follow-up is still debated. Further studies are required to investigate the role of this surgery in paediatric patients.

Allergic Fungal Otomastoiditis: A Case Report.

Otomastoiditis caused by an allergic reaction to fungi in the middle ear is rare, with only four cases reported in the English literature. We report the case of a patient with allergic fungal otomastoiditis. A 28-year-old man presented with otalgia, hearing loss, and vertigo. Exploratory tympanotomy revealed mucin with a peanut butter-like consistency and containing eosinophils and Candida parapsilosis, but no evidence of direct tissue invasion by fungi. The patient was treated with a combination of surgery and medication. Subtotal petrosectomy was finally performed to remove the middle ear mucosa and separate the middle ear from the external environment. Short-term prednisolone and long-term fluconazole were administered without satisfactory therapeutic results. The inflammatory condition has improved but continues without complete remission. Allergic fungal otomastoiditis is an extremely rare condition that may share pathophysiological features with allergic fungal rhinosinusitis, so a thorough examination combining bacterial cultures, histopathological examination with fungal staining, and serum antigen-specific immunoglobulin E against multiple fungi is essential. Optimal treatment probably comprises appropriate surgery and long-term administration of systemic corticosteroids. Definitive diagnostic criteria and therapeutic strategies need to be established, based on the accumulation of similar cases.

Treatment Strategies and Current Results of Petroclival Meningiomas.

Petroclival meningiomas (PCMs) are complex skull-base tumors that continue to pose a formidable surgical challenge to neurosurgeons because of their deep-seated location/intimate relationship with the brainstem and neurovascular structures. The advent of stereotactic radiosurgery (SRS), along with the shifting of management goals from complete radiological cure to maximal preservation of the patient's quality of life (QOL), has further cluttered the topic of "optimal management" in PCMs. Not all patients with PCM need treatment ("watchful waiting"). However, many who reach the neurosurgeons with a symptomatic disease need surgery. The goal of the surgery in PCMs is a GTR, yet this can be achieved in only less than half of the patients with acceptable morbidity. The remainder of the patients are better treated by STR followed by SRS for residual tumor control or close follow-up. A small subset of patients with PCM may be best treated by primary SRS. In this chapter, we have tried to summarize the scientific evidence pertaining to the management of PCMs (including the senior author's series), particularly those regarding the available treatment strategies and current outcomes, and discuss the decision-making process to formulate an "optimal management" plan for individual PCMs.

Systematic Review of Management and Survival Outcome of Parotid Cancers with Lateral Skull Base Invasion.

Lateral skull base involvement from parotid cancers is a rare condition and is considered a poor prognostic indicator. The aim of this study was to systematically review the literature of parotid tumors with temporal bone invasion to analyze the survival outcome. A systematic literature review was performed in August 2022, without time limits, and 289 patients affected by parotid gland cancers and lateral skull base involvement were included. The most common symptoms in parotid tumors at the onset were indolent mass, facial weakness, pain, and hearing loss; the chi-square value is 23.1063, with a statistically significance (p = < 0.000121). The five most common histologies were adenoid cystic carcinoma, acinic cell carcinoma, mucoepidermoid carcinoma, adenocarcinoma, and squamous cell carcinoma. The facial nerve function after surgery showed statistically significance (functional vs. non-functional; chi-square was 91.7698, p = < 0.00001). Mean follow-up was 36.2 months (range 0.3-192). At the last follow-up, more patients died of disease (DOD; 60/289, 21%) than other causes (DOOC; 5/289, 2%). There is a statistically significant correlation between patients died for tumor (DOD) and patients died for other causes (DOOC) (p = < 0.0001), suggesting that the lateral skull base invasion negatively impacts on survival. Basing on the results of our systematic review, lateral skull base involvement from parotid recurrent/advance tumors should be considered a poor prognostic factor, as the majority of patients die due to this condition. It also would be necessary to have "clear"works, with full data (demographic, clinical, surgical data), and with a longer follow up, in order to assess the best treatment modality of these patients.

Surgical Strategy in Modification of the Transpetrosal Approach to Avoid Postoperative Venous Complications: A Report of 74 Consecutive Cases.

BACKGROUND: The transpetrosal approach is a complex skull base procedure with a high risk of complications, particularly caused by injury of the venous system. It is in part related to variability of blood outflow pathways and their distinctive patterns in each individual patient. OBJECTIVE: To evaluate outcomes and complications after skull base surgery with use of the petrosal approach modifications, which selection was based on the detailed preoperative assessment of venous drainage patterns. METHODS: Overall, 74 patients, who underwent surgery via the transpetrosal approach at our institution between 2000 and 2017, were included in this study. In all cases, the venous drainage pattern was assessed preoperatively and categorized according to the predominant blood outflow pathway into four types as previously suggested by Hacker: (1) sphenoparietal sinus (SpPrt), (2) sphenobasal vein (SpB), (3) sphenopetrosal sinus (SpPS), and (4) cortical. The blood outflow through the bridging petrosal vein and the vein of Labbé was also taken into consideration. In patients with SpPrt- and a cortical-type venous drainage, the transpetrosal approach was used in a standard way. In patients with SpB-type venous drainage, limited extradural anterior petrosectomy was combined with intradural anterior petrosectomy after dural opening, superior petrosal sinus transection, tentorial cutting, Meckel's cave opening, and trigeminal nerve mobilization. In patients with SpPS-type venous drainage, after standard petrosectomy, dural opening, and tentorial cutting, SpPS ligation was done followed by 2-week interval before staged definitive tumor resection. RESULTS: Gross total, near-total, and subtotal resection of the lesion (meningioma, 48 cases; retrochiasmatic craniopharyngioma, 11 cases; brain stem cavernoma, 7 cases; other tumors, 8 cases) was achieved in 30 (40.5%), 24 (32.4%), and 20 (27.0%) patients, respectively. Postoperative complications that were possibly related to venous compromise were noted in 18 patients (24.3%), but neither one was major. Of these 18 patients, 9 were symptomatic, but all symptoms-aphasia (4 cases), seizures (2 cases), and confusion (3 cases)-fully resolved after conservative treatment. Overall, 13 patients, including 4 symptomatic, had signal changes on T2-weighted brain MRI, which were permanent only in 3 cases (all asymptomatic). CONCLUSION: Our suggested surgical strategy can be applied to any type of the venous drainage pattern. Preoperative evaluation and intraoperative preservation of the blood outflow pathways are crucial means for safe and effective application of the transpetrosal approach.

Cadaveric analysis of transcranial versus endoscopic transorbital petrosectomy: comparison of surgical maneuverability and brainstem exposure.

Introduction: While accessing the posterior fossa, the anterior transpetrosal approach (ATPA) and endoscopic transorbital approach (ETOA) use the same bony landmarks during petrous apex drilling. However, owing to their contrasting surgical axes, they are expected to show differences in surgical view, maneuverability, and clinical implications. This study aimed to investigate the feasibility of ETOA in accessing the brainstem and to compare the surgical view and maneuverability of each approach. Methods: ATPA and ETOA were performed in four human cadaveric heads (eight sides and four sides in each procedure). The angle of attack (AOA) and surgical depth were measured at the target of interest (root exit zone [REZ] of cranial nerve [CN] V, VI, and VII). When measuring the area of exposure, the brainstem was divided into two areas (anterior and lateral brainstem) based on the longitudinal line crossing the entry zone of the trigeminal root, and the area of each was measured. Results: ATPA showed significantly greater value at the trigeminal REZ in both vertical (31.8 ± 6.7° vs. 14.3 ± 5.3°, p=0.006) and horizontal AOA (48.5 ± 2.9° vs. 15.0 ± 5.2°, p<0.001) than ETOA. The AOA at facial REZ was also greater in ATPA than ETOA (vertical, 27.5 ± 3.9° vs. 8.3 ± 3.3°, p<0.001; horizontal, 33.8 ± 2.2° vs. 11.8 ± 2.9°, p<0.001). ATPA presented significantly shorter surgical depth (CN V, 5.8 ± 0.5 cm vs. 9.0 ± 0.8, p<0.001; CN VII, 6.3 ± 0.5 cm vs. 9.5 ± 1.0, p=0.001) than ETOA. The mean area of brainstem exposure did not differ between the two approaches. However, ATPA showed significantly better exposure of anterior brainstem than ETOA (240.7 ± 9.6 mm2 vs. 171.7 ± 15.0 mm2, p<0.001), while ETOA demonstrated better lateral brainstem exposure (174.2 ± 29.1 mm2 vs. 231.1 ± 13.6 mm2, p=0.022). Conclusions: ETOA could be a valid surgical option, in selected cases, that provides a direct ventral route to the brainstem. Compared with ATPA, ETOA showed less surgical maneuverability, AOA and longer surgical depth; however, it presented comparable brainstem exposure and better exposure of the lateral brainstem.