Surgical management of spontaneous middle cranial fossa defects: a systematic review and meta-analysis of available reconstructive techniques and materials.

Different materials and techniques have been proposed for surgical repair of spontaneous middle cranial fossa (MCF) defects. However, conclusive evidence supporting their selection and impact on clinical outcomes is lacking. The study aims to conduct a systematic review and meta-analysis on materials and techniques employed to repair MCF defects and evaluate complications and rates of recurrent cerebrospinal fluid (CSF) leaks. A PRISMA-guided systematic review and meta-analysis were performed using MESH terms and specific keywords including studies published before May 2022. Primary outcomes included recurrence of CSF leak and complication rates by type of reconstructive material and technique utilized. Meta-analyses of proportions were performed using random effects and confidence intervals for individual proportions were calculated using the Clopper-Pearson method. Twenty-nine studies were included (n = 471 cases). Materials employed for repair were categorized according to defect size: 65% of defects were of unknown size, 24% were small (< 1 cm), and 11% were large (≥ 1 cm). Rigid reconstruction (RR) was significantly favored over soft reconstruction (SR) for larger defects (94% of cases, p < 0.05). Complications and recurrent CSF leak rates of SR and RR techniques were comparable for defects of all sizes (p > 0.05). Complication rates reported for these procedures are low regardless of technique and material. RR was universally preferred for larger defects and analysis of complication and recurrence rates did not reveal differences regardless of defect size. While RR was more frequently reported in smaller defects, SR was used by several centers, particularly for smaller MCF floor defects.

The vectorial technique: a novel neuronavigation-based tool to measure angles of exposure during skull base dissections.

The angle of exposure (AnE) represents a metric that is particularly useful for analyzing circular bony structures during skull base dissections. The authors aimed to develop and validate a neuronavigation-based method to measure the AnE. A formula based on vectorial geometry and the coordinates of three points collected with a neuronavigation system was developed to measure the AnE. The method was validated using a plexiglass phantom head. To demonstrate its applicability, the authors measured the AnE in 6 cadaveric specimens after exposure of the hypoglossal canal using a far-medial approach (FMA) and a far-lateral transtubercular approach (FLTA) and in 6 different specimens after exposure of the jugular foramen using an FLTA and a retrosigmoid approach (RSA). The mean angles measured at 45°, 90°, and 180° using a goniometer during the validation test were 44.8° ± 1.1°, 90.8° ± 1.2°, and 179.7° ± 0.8° using the novel formula (p > 0.05). In the first illustrative application, the mean AnEs for the FMA and FLTA were 129° ± 0.9° and 243° ± 1.9°, respectively. In the second scenario, the mean AnEs were 192° ± 1.3° for the FTLA and 143° ± 2.1° for the RSA. The neuronavigation-based technique described is a highly accurate method to measure the AnE.

Quantitative Comparative Analysis of the Endoscope-Assisted Expanded Retrosigmoid Approach and the Far-Lateral Approach to the Inframeatal Area: An Anatomic Study With Surgical Implications.

BACKGROUND: The inframeatal area (IFMA) is a complex anatomic region of the posterior cranial fossa. Given its deep-seated location, tumors involving the IFMA represent a surgical challenge. OBJECTIVE: To objectively compare the endoscope-assisted expanded retrosigmoid approach (ERSA) and the far-lateral supracondylar transtubercular approach (FLTA) to address the IFMA. METHODS: Anatomic dissections were performed on 5 cadaveric heads (10 sides). The ERSAs were performed before and after the FLTAs. The surgical exposure, surgical freedom, and angles of attack to the IFMA were measured and compared for each approach. In addition, 2 illustrative clinical cases are reported. RESULTS: Compared with FLTA, ERSA yielded a nonsignificantly smaller mean area of exposure, whereas FLTA provided a significantly larger mean area of surgical freedom, compared with ERSA ( P = .002). The mean horizontal and vertical angles of attack were significantly different between the approaches. In the vertical plane, FLTA yielded the broadest angle of attack at the root entry zone of the lower cranial nerves (CN; P < .004), whereas ERSA did so at the dural entry zone of CN VII/VIII ( P = .006). In the horizontal plane, FLTA achieved its broadest angle of attack at the root entry zone of the lower CNs ( P = 1.83) while ERSA at the dural entry zone of CN VII/VIII ( P = .37). CONCLUSION: ERSA and FLTA granted a comparable exposure with the IFMA. Although FLTA may afford a larger area of surgical freedom, ERSA may be a suitable alternative to approach the IFMA, particularly to reach the most medial and superior aspects of this region. Conversely, FLTA may facilitate access to more caudally targets.

Contralateral Transmaxillary Approach to Petrous Apex Granuloma with Lateral Maxillotomy: 2-Dimensional Operative Video.

The endoscopic endonasal approach (EEA) has proven to be a valuable tool to access the petrous apex (PA).1 Although lesions located medial to the PA can be easily accessed through an EEA with minimal risk to the internal carotid artery (ICA), more laterally seated lesions represent a surgical challenge. The contralateral transmaxillary approach is an effective extension of the normal EEA to the PA, allowing a more lateral trajectory and thereby reducing the risks connected to paraclival ICA manipulation.2-4 This is a 47-year-old female presenting with tinnitus, hearing loss, and right facial twitching. The preoperative audiogram showed a 60 dB sensorineural hearing loss, and magnetic resonance imaging demonstrated an expansive lesion of the PA with high signal intensity in T1- and T2-weighted sequences. A high-riding jugular bulb ruled out the use of an infracochlear infralabyrinthine approach, and a middle cranial fossa approach was felt to render a high risk of recurrence due to the potential for incomplete resection. Ultimately, a contralateral transmaxillary approach was selected. Due to the extreme lateral position of the lesion, the maxillotomy was created in the lateral wall of the maxillary sinus to allow a coaxial approach to the PA. Postoperatively, the patient did not report new neurologic deficits. Anatomic pathology was consistent with cholesterol granuloma (Video 1). In the surgical management of PA granulomas, recognizing relevant anatomic structures such as the paraclival ICA, cochlea, jugular bulb, and vestibule preoperatively is of paramount importance to tailor the surgical approach and reduce its risks.

Radial Forearm Free Flap with Parapharyngeal Pedicle Corridor for Reconstruction of Anterior Skull Base Defects.

BACKGROUND: The radial forearm free flap (RFFF) is an indispensable tool for the reconstruction of a range of defects, including those of the skull base. Several options for routing of the RFFF pedicle have been described, and the parapharyngeal corridor (PC) has been proposed as an option and employed for a nasopharyngeal defect. However, there are no reports of its use for the reconstruction of anterior skull base defects. The objective of this study is to describe the technique for free tissue reconstruction of anterior skull base defects using the RFFF and routing of the pedicle via the PC. METHODS: Relevant neurovascular landmarks and critical surgical steps for reconstruction of anterior skull base defects with an RFFF and routing of the pedicle via the PC are reported using an illustrative clinical case and cadaveric dissections. RESULTS: We present a case of a 70-year-old man who underwent endoscopic transcribriform resection of cT4N0 sinonasal squamous cell carcinoma and was left with a large anterior skull base defect that persisted despite several repair attempts. An RFFF was utilized to repair the defect. This report is the first description of the clinical use of the PC for free tissue repair of an anterior skull base defect. CONCLUSIONS: The PC is an option for routing the pedicle during the reconstruction of anterior skull base defects. When the corridor is prepared as described in this case, a direct route exists from the anterior skull base to cervical vessels, simultaneously maximizing the reach of the pedicle and minimizing the risk of kinking.

A Cost-Effective and Reproducible Cadaveric Training Model for Internal Carotid Artery Injury Management During Endoscopic Endonasal Surgery: The Submersible Peristaltic Pump.

BACKGROUND: Internal carotid artery injury (ICAI) represents one of the most challenging complications in endoscopic endonasal neurosurgery and its rarity results in limited opportunities for trainees and surgeons to achieve proficiency in its management. Currently, available models for ICAI have employed costly systems that prevent their widespread use. The objective of this study is to validate an affordable submersible peristaltic pump (SPP)-based model as a reproducible and realistic paradigm for ICAI management training. METHODS: A laceration of the left parasellar internal carotid artery was purposely carried out in 2 human cadaveric heads. A blood substitute was perfused to ensure a perfusion flow of 1 L/min using an affordable SPP. A cohort of 20 neurosurgery and otolaryngology residents, fellows, and attendings were enrolled to evaluate the realism and content validity of the model using a validated 5-grade questionnaire. RESULTS: The model proved to mimic a real intraoperative scenario of ICAI with an expected output flow of 1 L/min. Questionnaire responses reported a realistic experience and the impact of this model on improving trainee surgical coordination and capability to rehearse the most accepted repair technique. The use of a fixed noninjected head allowed the reproducibility of the training session without the additional cost of new fresh-frozen heads. The affordable SPP allowed an impactful reduction of ICAI model training expenses maintaining high realism. CONCLUSIONS: The SPP-based ICAI model with noninjected cadaveric specimens is an affordable and cost-effective system that allows reproducibility and realism. These qualities favor greater adoption in neurosurgery and otolaryngology training curricula.

Thermal Analysis of an Ultrasonic Aspirator Micro Claw Tool Compared With Standard High-Speed Drilling During Internal Auditory Canal Opening in a Cadaveric Model.

BACKGROUND: The ultrasonic aspirator micro claw tool (UAmCT) can be used to remove the bone of the internal auditory canal (IAC) during vestibular schwannoma resection via the retrosigmoid approach (RSA) without the risk of a spinning drill shaft. However, the thermal profile of the UAmCT during IAC removal has not been reported. OBJECTIVE: To compare the thermal profile of the UAmCT during access of the IAC to that of a conventional high-speed drill (HSD) and to present an illustrative case of this application. METHODS: IAC opening via RSA was performed in 5 embalmed cadaveric specimens using the UAmCT with 3, 8, and 15 mL/min irrigation on the left and the HSD at 75 000 revolutions per minute and 0%, 14%, and 22% irrigation on the right. Peak bone surface temperatures were measured 4 times in 20-second intervals, and statistical analyses were performed using SPSS software. An illustrative case of a vestibular schwannoma resected via an RSA using the UAmCT to access the IAC is presented. RESULTS: The IAC was opened in all 5 specimens using both the UAmCT and HSD without complication. The mean peak bone surface temperatures were significantly lower with the UAmCT compared with the HSD ( P < .001). The UAmCT did not meaningfully prolong the operating time in the illustrative case, and the IAC was accessed without complication. CONCLUSION: The UAmCT may be a safe and effective alternative to HSD for IAC opening during vestibular schwannoma resection via the RSA. Larger studies under clinical conditions are required to further validate these findings.

Retrosigmoid Vestibular Neurectomy for Meniere Disease: A Technical Note.

BACKGROUND: Meniere disease (MD) is an idiopathic peripheral pathology involving the acoustic apparatus. One of the most critical challenges in managing MD is intractable vertigo. In this context, retrosigmoid vestibular neurectomy has been described as a safe and effective technique to manage this symptom when it is resistant to first- and second-line treatments. This article analyzed the alternative treatment options, specific surgical anatomy, and relevant details of vestibular neurectomies performed for intractable MD. METHODS: Relevant neurovascular landmarks, critical surgical steps, adequate indications, and potential pitfalls of retrosigmoid vestibular neurectomy were analyzed based on an illustrative clinical case of intractable MD. RESULTS: The illustrative case demonstrated how early recognition of the facial nerve and the vestibulocochlear plane is fundamental to performing retrosigmoid vestibular neurectomy. This procedure is indicated in cases of resistant MD with preoperative hearing integrity. Potential pitfalls of this technique are incomplete neurotomy, nerve regeneration, comorbidities in the contralateral ear, adverse anatomy, the possibility of nonotologic vertigo, and incomplete vestibular compensation. CONCLUSIONS: Vestibular neurectomy represents a safe and effective technique to manage MD that is resistant to medical treatment, allowing symptom control and hearing preservation. Nevertheless, detailed knowledge of surgical anatomy and possible pitfalls is of paramount importance to achieve a good outcome.

Keyhole supraorbital eyebrow approach for the resection of a tuberculum sellae meningioma with intraoperative endoscopic assistance.

Background: Tuberculum sellae meningiomas represent approximately 5-10% of intracranial meningiomas.[2] Although benign, they are associated with substantial morbidity, especially visual disturbance. At present, there are three main treatment options for patients with tuberculum sellae meningiomas: observational, with serial imaging follow; microsurgical resection; and stereotactic radiosurgery. The advantages of the supraorbital eyebrow craniotomy are the direct visualization of the anterior cranial fossa, anterior circulation, and the optical apparatus, reducing the extent of brain retraction, and the absence of risks of temporalis muscle hypotrophy and posterior chewing discomfort. Conversely, minor drawbacks are a steeper learning curve related to a narrower surgical corridor than a standard frontotemporal approach and the minimal risk of supraorbital nerve injury.[1,3]. Case Description: The authors report the case of a 42-year-old female who presented with acute-onset vision loss and only finger counting in her left eye associated with headache. Magnetic resonance imaging (MRI) showed a suprasellar extra-axial T1 enhancing mass with encasement of the left optic nerve and paraclinoid internal carotid artery and mass effect on the optic chiasm. A keyhole supraorbital eyebrow approach assisted with a microinspection tool was performed for tumor resection and optic nerve decompression. A Simpson Grade 2 tumor resection was achieved, and histopathology revealed a WHO Grade-I tuberculum sellae meningioma. The patient's presentation, rationale, key surgical steps, and outcome are discussed, and informed consent for surgery and video recording was obtained. Conclusion: This surgical video illustrates the use of a keyhole supraorbital eyebrow approach assisted with a microinspection endoscopic tool for the resection of a tuberculum sellae meningioma. The tumor size, extension, and preoperative clinical status determine the optimal surgical corridor in tuberculum sellae meningioma. The keyhole supraorbital eyebrow approach allows safe and direct access to anterior cranial fossa lesions.

Exoscope-Assisted Middle Cranial Fossa Approach for Repair of Tegmental Defects: A Cadaveric and Clinical Study.

BACKGROUND: Recent studies highlighted how exoscopes may be employed to approach the lateral skull base. The use of exoscope-assisted procedures to repair middle cranial fossa (MCF) defects has not been fully explored. The surgical microscope in the same circumstances has been associated with relevant limitations, such as its physical obstruction, among others. The aim of this study was to present a proof of concept of exoscope-assisted surgery for MCF defects. METHODS: A detailed step-by-step MCF approach was performed on 2 alcohol-preserved, latex-injected cadaveric specimens under exoscopic magnification. An illustrative clinical case of encephalocele secondary to a spontaneous tegmen tympani defect repaired via an exoscope-assisted MCF approach was presented. RESULTS: The most common sites of MCF defects, the tegmen tympani and the arcuate eminence, were successfully exposed under exoscopic magnification. Dissection was easily performed; no damage to the dura mater or to vascular or neural structures occurred. In the clinical case, the exoscope-assisted technique demonstrated adequate maneuverability and magnification quality. After localization, the encephalocele was resected, and the MCF defect was repaired. The surgeon's position was comfortable, and operative time was not prolonged. CONCLUSIONS: The exoscope allows adequate exposure of the MCF floor with identification and preservation of key anatomical structures. The exoscope represents a valuable alternative to the microscope in reconstruction of MCF defects, offering high-quality magnification and proven maneuverability.