Middle Fossa Approach Research Articles

The M-Point A Novel Landmark in Middle Fossa Surgery: A Cadaveric Morphometric Study

The arcuate eminence (AE) is an anatomically consistent bony protrusion located on the upper surface of the petrous bone that has been previously studied as a reference for lateral skull base approaches. There is a paucity of information in the neurosurgical literature seeking to improve the safety of the extended middle cranial fossa (MCF) approach using detailed morphometric analysis of the AE. To evaluate the use of the AE as an anatomical landmark to help with early identification of the internal acoustic canal (IAC) in MCF approaches by means of a cadaveric study, using a new morphometric reference termed the "M-point." A total of 40 dry temporal bones and 2 formalin-preserved, latex-injected cadaveric heads were used. The M-point was established as a new anatomic reference by identifying the intersection of a line perpendicular to the alignment of the petrous ridge (PR), originating from the midpoint of the AE, with the PR itself. Subsequent anatomical measurements were performed tomeasure the distance between M-point and IAC.Additional distances, including PR length and the anteroposterior and lateral AE surfaces, were also measured. The mean distance between the M-point and the center of the IAC was 14.9mm (SD ± 2.09), offering a safe drilling area during an MCF approach. This study provides novel information on identification of a new anatomic reference point known as the M-point that that can be used to improve early surgical identification of the IAC.

Audiometric Outcomes After the Middle Cranial Fossa Repair of Superior Semicircular Canal Dehiscence.

To evaluate the audiometric outcomes after the middle cranial fossa approach (MCF) for superior canal dehiscence (SCD) repair. Retrospective review. Tertiary referral center. SCD cases presented to a single institution between 2012 and 2022. The MCF repair of SCD. Air conduction (AC) threshold (250-8,000 Hz), bone conduction threshold (BC) (250-4,000 Hz), and air bone gap (ABG) (250-4,000 Hz) at each frequency, pure tone average (PTA) (500, 1,000, 2,000, 3,000 Hz). Among 202 repairs, 57% were bilateral SCD disease and 9% had previous surgery on the affected ear. The approach significantly narrowed ABG at 250, 500, and 1,000 Hz. The narrowing of ABG was achieved by both decreased AC and increased BC at 250 Hz, but mediated primarily by increased BC at 500 Hz and 1,000 Hz. Among cases without previous ear surgery, mean PTA remained in the normal hearing range (mean: preop, 21 dB; postop, 24 dB) and clinically important hearing loss (PTA increased by ≥10 dB) after the approach was noted in 15% of cases. Among cases with previous ear surgery, mean PTA remained in the mild hearing loss range (mean: preop, 33 dB; postop, 35 dB) and clinically important hearing loss after the approach was noted in 5% of cases. This is the largest study to date examining the audiometric outcomes after the middle cranial fossa approach for SCD repair. Findings of this investigation support that the approach is effective and safe with long-term hearing preservation for most.

Symptoms: Sudden Sensorineural Hearing Loss and Aural Fullness

Symptoms: Sudden Sensorineural Hearing Loss and Aural Fullness

Middle Fossa Approach to an Osteoma of the Internal Auditory Canal Facilitated by Augmented Reality: 2-Dimensional Operative Video.

De La Peña, Nicole M. BS*; Stonnington, Henry O. BA*; Bendok, Bernard R. MD‡,§,‖; Deep, Nicholas L. MD‖ Author Information

Intraoperative electrical stimulation for persistent, post-traumatic facial paralysis.

Approximately 7-10% of temporal bone fractures result in facial nerve paralysis. Treatment is dependent upon the severity of the nerve trauma and can range from conservative medical management to surgical intervention. A study by Hato et al. detailed the relationship between surgical timing and recovery rate for patients with facial nerve palsy secondary to temporal bone trauma. The rates of complete recovery and good recovery decline that the longer surgical intervention is delayed. We present the case of a 14-year-old male with a temporal bone fracture and delayed onset right-sided facial paralysis. This patient was treated with a transmastoid middle cranial fossa (MCF) approach with intraoperative electrical stimulation of the perigeniculate portion of the facial nerve. Despite a 53-day delay between trauma and surgical intervention, the patient's facial function improved from House Brackmann (HB) grade VI to grade II within 6months. Intraoperative facial nerve stimulation, which we have previously used for unresolved Bell's palsy, may be useful for patients with post-traumatic, persistent facial paralysis.

Lumbar Drain Use during Middle Fossa Approaches for Nonneoplastic Pathology of the Skull Base.

Introduction The middle fossa craniotomy (MFCs) is commonly utilized for spontaneous cerebrospinal fluid (CSF) leaks, encephaloceles, and superior semicircular canal dehiscence (SSCD). This study compares postoperative outcomes of MFCs with and without LD use. Methods A retrospective cohort study of adults over the age of 18 years presenting for the repair of nonneoplastic CSF leak, encephalocele, or SSCD via MFC from 2009 to 2021 was conducted. The main exposure of interest was the placement of an LD. The primary outcome was the presence of postoperative complications (acute/delayed neurologic deficit, meningitis, intracranial hemorrhage, and stroke). Secondary outcomes included operating room (OR) time, length of stay, recurrence, and need for reoperation. Results In total, 172 patients were included, 96 of whom received an LD and 76 who did not. Patients not receiving an LD were more likely to receive intraoperative mannitol ( n = 24, 31.6% vs. n = 16, 16.7%, p = 0.02). On univariate logistic regression, LD placement did not influence overall postoperative complications (OR: 0.38, 95% confidence interval [CI]: 0.05-2.02, p = 0.28), CSF leak recurrence (OR: 0.75, 95% CI: 0.25-2.29, p = 0.61), or need for reoperation (OR: 1.47, 95% CI: 0.48-4.96, p = 0.51). While OR time was shorter for patients not receiving LD (349 ± 71 vs. 372 ± 85 minutes), this difference was not statistically significant ( p = 0.07). Conclusion No difference in postoperative outcomes was observed in patients who had an intraoperative LD placed compared to those without LD. Operative times were increased in the LD cohort, but this difference was not statistically significant. Given the similar outcomes, we conclude that LD is not necessary to facilitate safe MCF for nonneoplastic skull base pathologies.

Comparative Anatomic Study Between Intradural Suboccipital Retrosigmoid and Extradural Transzygomatic Middle Fossa Approaches to Expose the Trigeminal Nerve

Meckel cave tumors are relatively rare, especially trigeminal nerve (TN) schwannomas. These tumors frequently project through the trigeminal pore, occupying the middle and posterior fossae. The most used routes to this region are the suboccipital retrosigmoid intradural approach (SORSA) and the transzygomatic middle fossa approach (TZMFA). Both approaches allow further exposure by adding intraoperative techniques, such as removing the suprameatal tubercle (retrosigmoid intradural suprameatal approach [RISA]) and the petrous apex (TZMFA-PA), respectively. This study aims to understand how TN exposure differs between both surgical approaches and how it increases by adding specific surgical maneuvers to these techniques. Five formalin-fixed adult cadaver heads were submitted to high-resolution computed tomography and their images were loaded into the neuronavigation device. Anatomic key points were defined along the outline of the TN, and their three-dimensional spatial locations were collected following each surgical approach. This process allowed the calculation of the TN exposed area obtained through each technique. The mean areas of exposure of the TN were 125.9 mm2 with SORSA and 208.9 mm2 with RISA, which represents an additional mean gain of 61.92% (P= 0.047). Using TZMFA, a mean exposure of 419.24 mm2 was obtained. When TZMFA-PA was used, the mean exposed area was 486.03 mm2, representing a mean gain in the exposure area of 16.81% (P= 0.072). Our study suggests that TZMFA allows better exposure of TN ganglionic and postganglionic segments, and the removal of the PA adds the preganglionic segment visualization, although with less TN exposed area compared with RISA. With SORSA, the additional suprameatal tubercle removal shows the trigeminal pore and the medial margin of the central portion of the TN ganglionic segment, making it possible to expose the mouth of the Meckel cave and part of its contents.

Transpetrosal Routes to the Skull Base-Anterior and Posterior Transpetrosal Approaches.

The extended middle fossa approach with anterior petrosectomy, or anterior transpetrosal approach, is a highly effective and direct approach to difficult-to-access petroclival tumors and basilar artery aneurysms. This surgical approach exposes a significant window of the posterior fossa dura between the mandibular nerve, internal auditory canal, and petrous internal carotid artery, below the level of the petrous ridge, and provides an unobstructed view of the middle fossa floor to the upper half of the clivus and petrous apex, without requiring removal of the zygoma. The posterior transpetrosal approaches, including the perilabyrinthine, translabyrinthine, and transcochlear approaches, provide direct and wide exposure of the cerebellopontine angle and posterior petroclival region. The translabyrinthine approach is commonly used for the removal of acoustic neuromas and other lesions of the cerebellopontine angle. We provide a stepwise description of how we perform these approaches and how to combine and extend them in order to achieve transtentorial exposure.

Manual neuronavigation for superior semicircular canal dehiscence surgery.

Intraoperative identification of a superior semicircular canal (SSC) dehiscence via the middle cranial fossa approach (MCFA) remains a difficult endeavor without a neuronavigation system. To address these challenges, we propose a technique to localize the SSC dehiscence intraoperatively using certain anatomical landmarks. Three anatomical landmarks should be identified on preoperative radiological images: the distance from the squamous part of the temporal bone to the dehiscent SSC, the lower limit of the craniotomy, and the exact location of the craniotomy in relation to the bony external auditory canal. The use of these landmarks intraoperatively can allow the surgeon to correctly identify the position of the SSC. Two instructional videos explaining this technique are presented. The proposed manual neuronavigation technique seems to be an accurate, safe, and cost-effective alternative technique for use in SSC dehiscence surgery.

Fibrin Glue–Coated Collagen Complex Patch: A Novel Material for Surgical Repair of Spontaneous Temporal Bone Cerebrospinal Fluid Leak and Encephalocele

To compare outcomes of surgical repair of temporal bone encephalocele and cerebrospinal fluid (CSF) leak using fibrin glue-coated collagen (FGCC) complex patch versus other materials for repair of dura. Retrospective chart review. Tertiary care hospital. Fifty-two adult patients undergoing transmastoid (TM), middle fossa (MF) or combined approach repair of spontaneous MF CSF leak between 2016 and 2020. Exposure of bony defect via TM approach, MF craniotomy, or combined TM/MF, and repair of the associated dura defect with FGCC complex patch, or other materials (acellular collagen matrix, bovine collagen, autologous fascia, fibrin tissue sealant). Successful repair without recurrent CSF leak or encephalocele throughout follow-up. Cost of materials used in duraplasty. Sixty-four percent of patients were female. Mean (standard deviation) age at repair was 61.4 (12.1) years. Mean (standard deviation) body mass index was 35.0 (8.3) kg/m 2 . Forty-nine (94%) patients had successful repair without known recurrence of CSF leak or encephalocele over a median follow-up interval of 11.7 months. Average duraplasty material cost was significantly lower with FGCC in comparison with other nonautologous materials (FGCC+: $1259.94, FGCC-: $1652.58; p = 0.004). No significant differences in recurrence risk (FGCC+: 6.9%, FGCC-: 6.9%; p > 0.999) or operative time (FGCC+: 153.7 min, FGCC-: 155.4 min; p = 0.88) were detected based on material used for duraplasty. All materials studied demonstrate effective and sustained means of repair for MF CSF leak and encephalocele, including in the presence of multiple defects. Use of FGCC for duraplasty produces noninferior surgical results to other nonautologous materials in repair of spontaneous CSF leaks of the temporal bone and may be more cost-effective.

Incidence of Postoperative CSF Leaks in Class III Obese Patients Undergoing Middle Cranial Fossa Approach for Spontaneous CSF Leak Repair.

To determine the safety and effectiveness of the middle cranial fossa (MCF) approach for spontaneous cerebrospinal fluid leak (sCSF-L) repair in class III obese patients. To also assess the need for prophylactic lumbar drain (LD) placement in this patient population. Retrospective cohort study. Tertiary Academic Center. All patients older than 18 years undergoing sCSF-L repair with an MCF approach. An MCF craniotomy for sCSF-L repair. Rate of complications and postoperative leaks. There were no perioperative complications in 78.9% (56/71) of cases. The surgical complication rate was 12.5% (2/16), 10% (2/20), and 22.2% (6/27) in class I, class II, and class III obese patients. There was no statistically significant difference in complications among these three groups. The most common postoperative complication was a persistent CSF leak in the acute postoperative period with an overall rate of 9.9% (7/71) with six of the seven patients requiring postoperative LD placement. The percentage of postoperative CSF leaks in nonobese, class I, class II, and class III patients were 25% (2/8), 12.5% (2/16), 0% (0/20), and 11.1% (3/27), respectively. There was no statistically significant difference in the rate of postoperative CSF leaks among the four groups (chi-square, p = 0.48). In all cases, the acute postoperative CSF leaks resolved in the long term and did not require further surgical repair. We determine that MCF craniotomy repair for sCSF-Ls is safe in patients with class III obesity, and the incidence of postoperative CSF leaks did not vary among other obesity classes. We also find that prophylactic placement of LDs is not routinely needed in this population.

Vestibular Schwannoma Surgery with Endoscope-Assisted Retrolabyrinthine Approach under Modified Reinforced Continuous Intraoperative Monitoring for Hearing Preservation: Experience of 33 Cases in a Single Center.

Surgery for vestibular schwannoma includes various techniques such as the middle cranial fossa, suboccipital, translabyrinthine, and retrolabyrinthine approaches. The retrolabyrinthine approach does not impair the labyrinth and allows postoperative hearing preservation. Previously, we reported an endoscope-assisted retrolabyrinthine approach under reinforced continuous intraoperative monitoring for preservation of hearing and facial nerve function. However, the hearing preservation rate was relatively low in patients with long-wave V latency in the auditory brainstem response or poor otoacoustic emission response under this approach. Thus, the hearing preservation rate in such patients remains to be improved. To overcome this limitation, we modified the previous approach. In 26 of the 33 consecutive cases (79%) over the last three years, preservation of hearing equivalent to that before surgery or improved hearing was achieved. Postoperative deafness was observed in only two of the 33 cases (6%). According to previous reports, the rate of hearing preservation using the retrolabyrinthine approach is approximately 30-50%. Therefore, we have achieved a higher hearing preservation rate than that previously reported using the endoscopy-assisted retrolabyrinthine approach under reinforced continuous intraoperative monitoring. These improvements in our department are considered to be helpful for hearing preservation.

Subfascial dissection and extended temporal muscle detachment for middle fossa approach.

The soft tissue dissection for the middle fossa approach requires adequate management of the neuro, vascular, and muscular structures in order to maximize exposure and diminish morbidities. An incision anterior to the tragus is performed, extending from the zygomatic process to the superior temporal line. The superior temporal artery is exposed, followed by a subfascial dissection of the frontalis nerve. The temporal muscle is dissected and released from the zygoma. All cranial landmarks are exposed for the 5 × 5cm temporal fossa craniotomy. This novel approach provides a safe and adequate access to perform an extended middle fossa craniotomy.

A Case of Supralabyrinthine Petrous Bone Cholesteatoma Mimicking Facial Nerve Schwannoma

We report the case of a 31-year-old woman with a supralabyrinthine petrous bone cholesteatoma who presented with acute facial paralysis, without other symptoms; she had first noticed the symptoms 2 months earlier. She was prescribed oral steroid therapy at a previous clinic, which had proved ineffective. Examination revealed a normal appearance of the tympanic membrane, and pure tone audiometry showed no evidence of hearing loss. Computed tomography (CT) revealed a spindle-shaped soft-tissue lesion occupying the labyrinthine segment of the facial nerve coursing to the epitympanum. Gadolinium-enhanced magnetic resonance imaging (MRI) revealed a non-enhancing mass in the same region. A provisional diagnosis of facial nerve schwannoma was made on clinical and radiological grounds, and surgical resection was performed via a middle fossa approach. Keratin debris was found along the labyrinthine segment of the facial nerve coursing to the ossicles, which led us to make the diagnosis of cholesteatoma. The lesion was completely resected along with the head of the malleus and incus by mastoidectomy, and ossiculoplasty was performed. Histological examination confirmed the diagnosis of cholesteatoma. The patient’s facial paralysis failed to recover. In patients with a small lesion in the petrous bone who present with isolated facial palsy as the only clinical manifestation, it is often difficult to differentiate between a cholesteatoma and facial nerve schwannoma, and gadolinium-enhanced MRI is a useful imaging examination to differentiate between the two diseases. In the present case, facial nerve schwannoma was suspected as the most likely diagnosis based on the clinical presentation and CT findings; however, the lack of enhancement on gadolinium MRI pointed to the diagnosis of cholesteatoma. Physicians should be aware of these clinical aspects for appropriate treatment planning.

How I do it: internal maxillary artery to middle cerebral artery bypass to manage giant thrombosed internal carotid artery aneurysm.

Internal maxillary artery (IMA) bypass has become popularized due to its medium-to-high blood flow, short graft length, and well-matched arterial caliber between donor and recipient vessels. We described an open surgery of a NEW "workhorse," the IMA bypass, to treat a giant, thrombosed cerebral aneurysm. The extracranial middle infratemporal fossa (EMITF) approach was used to unveil the pterygoid segment of the IMA for cerebral revascularization. Although this technique is technically challenging, the variations in IMA can be effectively identified and sufficiently exposed in this technique to achieve favorable clinical outcomes with a high bypass patency rate.

Surgical Closure of the Eustachian Tube Through Middle Fossa and Transmastoid Approaches: A Pilot Cadaveric Anatomy Study.

Cerebrospinal fluid rhinorrhea after temporal bone surgery involves drainage from the Eustachian tube (ET) into the nasopharynx, causing significant patient morbidity. Variable anatomy of the ET accounts for failures of currently used ET obliteration techniques. To describe the surgical anatomy of the ET and examine possible techniques for ET closure through middle fossa (MF) and transmastoid approaches. We described the surgical anatomy of the ET from the MF and transmastoid approaches in 5 adult cadaveric heads, measuring morphometric and surgical anatomy parameters and establishing targets for definite ET obliteration. The osseous ET measured an average of 19.53 mm (±1.56 mm), with a mean diameter of 2.24 mm (±0.29 mm). The shortest distance between the greater superficial petrosal nerve and the ET junction was 6.61 mm (±0.61 mm). Shortest distances between the ET junction and the foramen spinosum and posterior border of the foramen ovale were 1.09 mm (±0.24 mm) and 2.03 mm (±0.30 mm), respectively. Closure of the cartilaginous ET may be performed by folding it in on itself, securing it by packing, suturing, or surgical clip ligation. Definite obliteration of the cartilaginous ET appears feasible and the most definite approach to eliminate egress of cerebrospinal fluid to the nasopharynx using the MF approach. This technique may be used as an adjunct to skull base procedures where ET closure is planned.

Long-term complications of the transmeatal approach (Open Transcanal) in cochlear implants: A follow-up study

ObjectiveMultiple alternative approaches of cochlear implant surgery have been described, such as the suprameatal approach, transcanal approach, transmeatal approach and middle cranial fossa approach. Transmeatal (open trnascanal) approach has not been adapted since first described in the clinical field. we aimed to assess the long-term complications of the transmeatal approach in a series of 131 patients at our center between 2004 and 2008. MethodsThis study was a retrospective case series of all patients who underwent cochlear implants with the transmeatal (open transcanal) approach from May 2004 to December 2008 at King Faisal Specialist and Research Hospital (Riyadh, Saudi Arabia), which were conducted by the same surgeon. ResultsComplications were observed often with various combinations—recurrent otitis externa, posterior tympanic membrane perforation, electrode extrusion, cholesteatoma, and chronic mastoiditis. The overall long-term complication rate was 16% (21/131). The gap between the implantation and the diagnosis of a complication ranged from <1 year to 11 years. Major complications were as follows: cholesteatoma in 5 (3.8%) patients, extrusion of the electrode in 5 (3.8%) patients, and tympanic membrane perforation or deep retractions in 5 (3.8%) patients. Minor complications were as follows: recurrent mastoiditis with/without concomitant temporary facial nerve palsy in 4 (3%) patients, recurrent otitis externa infections in 7 (5%) patients, and weakness of the posterior canal wall in 1 patient. ConclusionThe transmeatal approach posed an high rate of complications on long-term follow-up such as cholestetoma formation, extrusion of electrode or perielectrode reaction formation to tympanic membrane and external auditory canal

Symptoms: Purple Ear Drum and Hearing Loss

Symptoms: Purple Ear Drum and Hearing Loss

Current Trends in Endoscopic Ear Surgery.

Current Trends in Endoscopic Ear Surgery.

C-CASE 2022: Competence to Excellence01. The Queen Bee phenomenon in Canadian surgical subspecialties: an evaluation of gender biases in the resident training environment02. Barriers to surgical peer coaching — What have we learned, and where do we go from here?03. Shared decision-making and evidence-based medicine: Pivotal or trivial to patient care in orthopedic trauma?04. Immersive virtual reality and cadaveric bone

# 01. The Queen Bee phenomenon in Canadian surgical subspecialties: an evaluation of gender biases in the resident training environment {#article-title-2} The Queen Bee phenomenon describes the behavioural response that occurs when women achieve success in a male-dominated environment, and in this