UNASSIGNED: To study the microanatomic structure of the subtemporal transtentorial approach to the lateral side of the brainstem, and to provide anatomical information that will assist clinicians to perform surgeries on the lateral, circumferential, and petroclival regions of the brainstem.
UNASSIGNED: Anatomical investigations were conducted on 8 cadaveric head specimens (16 sides) using the infratemporal transtentorial approach. The heads were tilted to one side, with the zygomatic arch at its highest point. Then, a horseshoe incision was made above the auricle. The incision extended from the midpoint of the zygomatic arch to one third of the mesolateral length of the transverse sinus, with the flap turned towards the temporal part. After removing the bone, the arachnoid and the soft meninges were carefully stripped under the microscope. The exposure range of the surgical approach was observed and the positional relationships of relevant nerves and blood vessels in the approach were clarified. Important structures were photographed and the relevant parameters were measured.
UNASSIGNED: The upper edge of the zygomatic arch root could be used to accurately locate the base of the middle cranial fossa. The average distances of the star point to the apex of mastoid, the star point to the superior ridge of external auditory canal, the anterior angle of parietomastoid suture to the superior ridge of external auditory canal, and the anterior angle of parietomastoid suture to the star point of the 10 adult skull specimens were 47.23 mm, 45.27 mm, 26.16 mm, and 23.08 mm, respectively. The subtemporal approach could fully expose the area from as high as the posterior clinoid process to as low as the petrous ridge and the arcuate protuberance after cutting through the cerebellar tentorium. The approach makes it possible to handle lesions on the ventral or lateral sides of the middle clivus, the cistern ambiens, the midbrain, midbrain, and pons. In addition, the approach can significantly expand the exposure area of the upper part of the tentorium cerebelli through cheekbone excision and expand the exposure range of the lower part of the tentorium cerebelli through rock bone grinding technology. The total length of the trochlear nerve, distance of the trochlear nerve to the tentorial edge of cerebellum, length of its shape in the tentorial mezzanine, and its lower part of entering into the tentorium cerebelli to the petrosal ridge were (16.95±4.74) mm, (1.27±0.73) mm, (5.72±1.37) mm, and (4.51±0.39) mm, respectively. The cerebellar tentorium could be safely opened through the posterior clinoid process or arcuate protrusion for localization. The oculomotor nerve could serve as an anatomical landmark to locate the posterior cerebral artery and superior cerebellar artery.
UNASSIGNED: Through microanatomic investigation, the exposure range and intraoperative difficulties of the infratemporal transtentorial approach can be clarified, which facilitates clinicians to accurately and safely plan surgical methods and reduce surgical complications.

Objectives  The complicated anatomy in the parasellar region of the middle cranial fossa renders a surgical challenge in the management of cavernous malformation in this region. We demonstrate the resection of a cavernous malformation in this operative video. Design  The procedure is presented via a surgical instructional video. Setting  The operation was performed by a skull base team in a tertiary neurosurgical center. Participant  A 49-year-old female presented with intermittent headache and right facial numbness for 6 months. Physical examination suggested a decreased sensation of pain, temperature, and light-touch on the right side of the face. Magnetic resonance imaging indicated that a space-occupying lesion located in the middle cranial fossa. Results  Gross total resection was achieved, and the cranial nerve function was preserved. Conclusion  The lesion involving middle cranial fossa should be managed meticulously. Transnasal endoscopic approach is a good option for the resection of the lesion. Simultaneously, the cavernous sinus should be protected to a great extent in case of bleeding and cranial nerve injury. The link to the video can be found at https://youtu.be/tbN8tuEb6nM ( Figs. 1 and 2 ).

OBJECTIVE: Dermoid cysts (DCs) are congenital, slowly growing, and may cause nervous system symptoms. Related literature is limited and mainly includes case reports. We report a case series of DCs originating from the middle cranial fossa floor (MCFF) and investigate their demographic information, clinical characteristics, imaging findings, surgical procedures, and prognostic outcomes.
METHODS: We reviewed the patients with DCs arising from the MCFF undergoing endoscopic endonasal surgery (EES) in our center between 2012 and 2022.
RESULTS: A total of 5 patients with DCs were enrolled (2 males and 3 females), with a mean age of 46.2 years at the onset. All DCs originated from the MCFF with 1 case involving the middle cranial fossa bone and another 1 case affecting the dura mater. One (20.0%) patient had neurological involvement. After admission, all patients received EES with a total resection rate of 100.0% (5 of 5). After a median follow-up of 73.2 months, all patients achieved complete clinical and radiological improvements. No surgical-related complications or relapses were observed during the long-term follow-up.
CONCLUSIONS: Endoscopic endonasal surgery is considered a safe and effective approach for the treatment of DCs in the MCFF. A larger sample size and longer follow-up time are needed.

The endoscopic transnasal maxillary sinus approach is usually performed in resecting tumors located in the pterygopalatine fossa and infratemporal fossa, but is rarely used in the resection of lesions in the middle cranial fossa. Because of the complicated anatomical structure of the middle cranial fossa, trigeminal schwannomas (TSs) located in this region are usually dissected through conventional craniotomy surgical approaches; however, the endoscopic transnasal maxillary sinus approach can be used in resection of middle cranial fossa TSs. The current study presented the case of a 59-year-old man who suffered intermittent headaches for 2 years without other notable medical history and neurological abnormalities. The patient was diagnosed with a middle cranial fossa TS. After imaging and assessment of anatomical features, the tumor was totally resected through the transnasal maxillary sinus approach. Following surgery, the symptoms were relieved and the patient returned to a normal life. Light numbness was complained of in the distribution area of the maxillary nerve of the right side of the face, but this was gradually relieved. Combined with a literature review, the present case indicated that the endoscopic transnasal maxillary sinus approach may provide a safer and more direct option for resecting middle cranial fossa lesions, which is worthy of increased clinical application.

BACKGROUND: Pseudogout is a benign joint lesion caused by the deposition of calcium pyro-phosphate dihydrate crystals, but it is invasive. Pseudogout of the temporo-mandibular joint (TMJ) is uncommon, and it rarely invades the skull base or penetrates into the middle cranial fossa. The disease has no characteristic clinical manifestations and is easily misdiagnosed.
METHODS: We present two cases of tophaceous pseudogout of the TMJ invading the middle cranial fossa. A 46-year-old woman with a history of diabetes for more than 10 years was admitted to the hospital due to swelling and pain in the right temporal region. Another patient, a 52-year-old man with a mass in the left TMJ for 6 years, was admitted to the hospital. Maxillofacial imaging showed a calcified mass and severe bone destruction of the skull base in the TMJ area. Both patients underwent excision of the lesion. The lesion was pathologically diagnosed as tophaceous pseudogout. The symptoms in these patients were relieved after surgery.
CONCLUSIONS: Tophaceous pseudogout should be considered when there is a calcified mass in the TMJ with or without bone destruction. A pathological examination is the gold standard for diagnosing this disease. Surgical treatment is currently the recommended treatment, and the prognosis is good after surgery.

BACKGROUND: The anterolateral triangle enclosed by the foramen rotundum and foramen ovale constitutes part of the floor of the middle cranial fossa (MCF).
OBJECTIVE: To assess the feasibility of a transnasal prelacrimal approach for accessing the floor of MCF via an anterolateral triangle corridor and to determine the extent of maximal exposure while safeguarding neurovascular structures.
METHODS: A transnasal prelacrimal approach was performed in 5 cadaveric specimens (10 sides). Following the identification of foramen rotundum and foramen ovale, the bony ridge between 2 was drilled to expose the MCF. The temporal lobe dura was then elevated laterally, and the distances from foramen ovale to the respective borders of the area of the MCF window were measured using a surgical navigation device.
RESULTS: The MCF was exposed with a 0° scope in all specimens also exposing significant landmarks including the middle meningeal artery, greater superficial petrosal nerve, superior petrous sinus, and arcuate eminence. Average distances from foramen ovale to the anterior, posterior, and lateral exposed borders were 22.86 ± 1.87 mm, 27.24 ± 0.94 mm, and 24.23 ± 1.61 mm, respectively. The average area of exposed MCF window was 554.12 ± 60.22 mm2. Preservation of vidian nerve, greater palatine nerve, lateral nasal wall, and nasolacrimal duct was possible in all 10 sides.
CONCLUSIONS: It is feasible to access the floor of MCF via an endoscopic transnasal prelacrimal approach with seemingly low risk.

Growing skull fracture (GSF) is an uncommon post-traumatic complication, which accounts for approximately 0.05% to 1% of all skull fractures. Delayed diagnosis of GSF in adulthood is rare and often involved with a variety of neurological symptoms. Here, we reported an adult patient, with an interval of 17 years from initial head trauma to first diagnosis of GSF. The patient complained of short periods of fainting and bilateral visual hallucinations, with a hard palpable bulge around his right occipitomastoid suture region. Computed tomographic imaging demonstrated an arachnoid cyst extending into right mastoid cavity. Consequently, the delayed diagnosis of GSF was confirmed, and the patient was managed with duroplasty and cranioplasty. At the 8-month follow-up, the patient showed an uneventful postoperative recovery. A comprehensive literature review was also conducted, and a total of 70 GSF cases were identified and summarized. According to the literature review, patients with GSF generally have a history of head trauma in their childhood, and delayed diagnosis is a common situation. Diagnosis of GSF should include complete retrospective medical history, physical, and imaging examinations. Once the diagnosis is confirmed, cranioplasty accompanied with duroplasty might be the most effective way to relieve symptoms and prevent further damage.

Background  Zygomatic osteotomy, an adjunct to middle cranial fossa (MCF) surgical approaches, improves the superior-inferior angle of approach and minimizes temporal lobe retraction. However, a decision-making algorithm for selective use of the zygomatic osteotomy and the impact of the zygomatic osteotomy on surgical complications have not been well documented. Objective  We described an algorithm for deciding whether to use a zygomatic osteotomy in MCF surgery and evaluated complications associated with a zygomatic osteotomy. Methods  A retrospective review of MCF cases over 11 years at our academic tertiary referral center was conducted. Demographic variables, tumor characteristics, surgical details, and postoperative complications were extracted. Results  Of the 87 patients included, 15 (17%) received a zygomatic osteotomy. Surgical trajectory oriented from anterior to posterior (A-P) was significantly correlated with the use of the zygomatic osteotomy. Among the cases approached from A-P, we found (receiver-operating characteristic curve) that the cut-off tumor size that predicted a zygomatic osteotomy was 30 mm. Of the 87 cases included, 15 patients had a complication. The multivariate logistic regression model failed to reveal any significant correlation between complications and zygomatic osteotomies. Conclusions  We found that the most important factor determining the use of a zygomatic osteotomy was anticipated trajectory. A-P approaches were most highly correlated with zygomatic osteotomy. Within those cases, a lesion size cut-off of 30 mm was the secondary predicting factor of zygomatic osteotomy use. The odds of suffering a surgical complication were not significantly increased by use of zygomatic osteotomy.

Dislocation of the mandibular condyle is one of several consequences of facial trauma that can be anticipated. The condylar neck is inherently weak and likely to fracture at the time of impact before dislocating into the middle cranial fossa. A review of the literature revealed that most cases of dislocation of the mandibular condyle into the middle cranial fossa are treated by open reduction and internal fixation via an extraoral approach or are treated conservatively with closed reduction. An intraoral approach is rare. Here we present a patient with traumatic dislocation of the mandibular condyle into the middle cranial fossa who was treated successfully by condylectomy and coronoidectomy through an intraoral approach and intermaxillary fixation followed by mouth-opening exercises and rehabilitation. Stable occlusion and movement of the mandible was achieved and the long-term results have been good. The intraoral approach may be an option in patients with traumatic dislocation of the mandibular condyle into the middle cranial fossa.

OBJECTIVE Multiple approaches have been designed to reach the medial middle fossa (for lesions in Meckel\'s cave, in particular), but an anterior approach through the greater wing of the sphenoid (transalisphenoid) has not been explored. In this study, the authors sought to assess the feasibility of and define the anatomical landmarks for an endoscopic anterior transmaxillary transalisphenoid (EATT) approach to Meckel\'s cave and the middle cranial fossa. METHODS Endoscopic dissection was performed on 5 cadaver heads injected intravascularly with colored silicone bilaterally to develop the approach and define surgical landmarks. The authors then used this approach in 2 patients with tumors that involved Meckel\'s cave and provide their illustrative clinical case reports. RESULTS The EATT approach is divided into the following 4 stages: 1) entry into the maxillary sinus, 2) exposure of the greater wing of the sphenoid, 3) exposure of the medial middle fossa, and 4) exposure of Meckel\'s cave and lateral wall of the cavernous sinus. The approach provided excellent surgical access to the anterior and lateral portions of Meckel\'s cave and offered the possibility of expanding into the infratemporal fossa and lateral middle fossa and, in combination with an endonasal transpterygoid approach, accessing the anteromedial aspect of Meckel\'s cave. CONCLUSIONS The EATT approach to Meckel\'s cave and the middle cranial fossa is technically feasible and confers certain advantages in specific clinical situations. The approach might complement current surgical approaches for lesions of Meckel\'s cave and could be ideal for lesions that are lateral to the trigeminal ganglion in Meckel\'s cave or extend from the maxillary sinus, infratemporal fossa, or pterygopalatine fossa into the middle cranial fossa, Meckel\'s cave, and cavernous sinus, such as schwannomas, meningiomas, and sinonasal tumors and perineural spread of cutaneous malignancy.