Floor Of Middle Cranial Fossa Research Articles

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 (< 1cm), and 11% were large (≥ 1cm). 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.

Endoscopic Endonasal Surgery for Dermoid Cysts Arising From the Middle Cranial Fossa Floor: A Rare Case Series.

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. We reviewed the patients with DCs arising from the MCFF undergoing endoscopic endonasal surgery (EES) in our center between 2012 and 2022. A total of 5 patients with DCs were enrolled (2 males and 3 females), with a mean age of 46.2years 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 73.2months, all patients achieved complete clinical and radiological improvements. No surgical-related complications or relapses were observed during the long-term follow-up. 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.

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

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. 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. 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. 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.

Endoscopic Transorbital Approach to the Middle Fossa: Qualitative and Quantitative Anatomic Study.

The endoscopic superior eyelid transorbital route to the skull base is gaining progressive popularity in the neurosurgical community. To evaluate the anatomy of the middle cranial fossa from this novel ventral perspective to reach the skull base through the transorbital route and to show limits for possible safe middle fossa drilling from the transorbital route. Anatomic study was performed; 5 cadaveric specimens (ie, 10 sides) and 2 dry skulls (ie, 4 sides) were dissected. To obtain a functional result, there are boundaries that correspond to neurovascular structures that traverse, enter, or leave the middle fossa that must be respected: inferiorly, the lateral pterygoid muscle; medially, the Gasserian ganglion and the lateral border of the foramen rotundum; laterally, the foramen spinosum with the middle meningeal artery; superiorly, the lesser sphenoid wing; posteriorly, the anterior border of the foramen ovale. Average bone resected was 6.49 ± 0.80 cm3 which is the 63% of total middle fossa floor. The mean axial surgical length calculated was 3.85 cm (3.18-5.19 cm) while the mean sagittal surgical length was 5.23 cm (4.87-6.55 cm). The mean horizontal angle of approach was 38.14° (32.87°-45.63°), while the mean vertical angle of approach was 18.56° (10.81°-26.76°). Detailed anatomy of the middle cranial fossa is presented, and herewith we demonstrated that from the endoscopic superior eyelid transorbital approach removal of middle cranial fossa floor is possible when anatomic landmarks are respected.

Postoperative Outcomes of Patients with Thin Bone Overlying the Superior Semicircular Canal: A Single Institution's Experience

Superior semicircular canal dehiscence (SSCD) is defined by a bony defect overlying the superior semicircular canal (SSC) in the middle cranial fossa floor, causing a myriad of vestibular and auditory symptoms. Patients with thin bone without full dehiscence overlying the SSC also present with similar symptoms. There are currently no guidelines for surgical management of patients with thin bone. The authors offer their experience with thin bone patients to characterize their symptomatology and explore whether these patients benefit from surgical intervention typically offered to SSCD patients. Two hundred fifty-six patients evaluated for SSCD from 2011 to 2019 were reviewed. High-resolution coronal computed tomography scans with 0.6-mm slice thickness of the temporal bones were assessed to determine whether the patient had a true dehiscence or a thin bone covering overlying the SSC. Bone that was ≤0.5mm was considered to be "thin bone." Parameters of interest included patient demographics as well as preoperative and postoperative symptomatology. A P value < 0.05 was considered statistically significant. Forty-eight patients met inclusion criteria of having "thin bone." The mean age was 48.13±12.03years, and 65.5% of patients were female. Of the preoperative symptoms evaluated, the greatest postoperative symptomatic resolution was noted in hearing loss (92.3%), vertigo (94.4%), and oscillopsia (100%). Dizziness (56.5%) had the lowest symptomatic resolution rate. Surgical management of thin bone patients via middle fossa craniotomy, a similar technique to SSCD repair, provides significant symptomatic resolution. Therefore, surgery should be considered in thin bone patients with debilitating symptoms, albeit not having a true dehiscence.

Middle Cranial Fossa Approach to Repair Tegmen Dehiscence Using Self-setting Calcium Phosphate Cement: A Retrospective Case Review.

To review the outcomes of repairing tegmen dehiscence using the middle cranial fossa approach with a self-setting bone cement. Retrospective case series. Two academic tertiary hospitals. All patients presenting for surgical repair of tegmen dehiscence and with postoperative follow-up for at least 6 months between October 2015 and July 2019. Surgical repair using a middle cranial fossa approach using a layered reconstruction with temporalis fascia and self-setting calcium phosphate bone cement. Perioperative complications, recurrence of presenting symptoms/disease, hearing, and facial nerve grade. The cohort consisted of 22 patients with 23 tegmen dehiscence repairs (1 sequential bilateral repair). There were 16 males and 6 females with an average age at operation of 52.6 years. Repairs were left sided in 9, right sided in 12 patients, and bilateral in 1 patient. No patients had recurrence of presenting symptoms or disease at most recent follow-up. Preoperative hearing was maintained in all patients. Two patients (9% of repairs) experienced delayed partial temporary facial nerve weakness House-Brackman grade 2 and 4 which had recovered by 8 weeks postoperative. We demonstrate a technique for repairing tegmen dehiscence of the middle cranial fossa floor that has excellent postoperative outcomes. We highlight potential technical challenges in this approach as well as the need for counseling for potential partial transient facial nerve dysfunction.

Surgical anatomy of basal turn in relation to middle cranial fossa and round window as pertaining to middle fossa cochlear implant technique.

The purpose of this investigation was to evaluate the relation of the basal turn of cochlea with middle cranial fossa and round window as pertaining to middle cranial fossa cochlear implant technique. Fifty-four formalin preserved temporal bones were micro-dissected to expose the basal turn. The point (f) was marked on the basal turn of cochlea where there was minimum distance of basal turn of cochlea from the floor of middle cranial fossa (f1). The f-f1 distance, the angle (∠smf) and distance of point "f" from the round window (s-f) was measured. The mean minimum distance between basal turn of cochlea and floor of middle cranial fossa (f-f1) was 2.0 ± 0.7mm.The point f was at mean distance (s-f) and angle (∠smf) of 14.7 ± 1.6mm and 217° ± 13.7° from round window, respectively. The information may be helpful for designing appropriate electrode array for middle fossa technique especially for deciding the length of electrode array towards round window, as otherwise electrode may extend into vestibule of inner ear. In the cases where bone thickness between superior part of basal turn of cochlea and middle cranial fossa is < 1.5mm, surgeon should be extra cautious.

Middle Cranial Fossa Approach: The Incudomalleolar Joint as a Reliable Landmark.

Introduction The middle cranial fossa approach is performed by fewer neurotologists owing to a reduced number of indications. Consistent landmarks are mandatory to guide the surgeon in a narrow field. Objectives We have evaluated the incus and malleus head and the incudomalleal joint (IMJ) as a key landmark for identifying the superior semicircular canal (SSC) and to get oriented along the floor of the middle cranial fossa. Methods A combination of 20 temporal bone dissections and CT imaging were utilized to test and describe these landmarks. Results The blue line of the SSC is consistently identified along the prolongation of a virtual line through the IMJ and the angulation toward the root of zygoma. The mean distance from the zygoma toward the IMJ ranged from 1.60 to 1.90cm. Once the IMJ was identified, the blue line of the SSC was consistently found along the virtual line through the IMJ within 5 to 9mm. Conclusions The IMJ is a safe and consistent anatomical marker in the surgical approach to the middle cranial fossa floor. Opening the tegmen 1.5 to 2cm medial to the root of the zygoma and identifying the joint allows to trace a virtual line toward the SSC within 5 to 9mm. Knowledge of the close relationship between the direction of the IMJ and the superior canal can be used in all transtemporal approaches, thus orienting the surgeon in a rather narrow field with limited retraction of the dura and brain.

Cadaveric Simulation of Otologic Procedures: An Analysis of Droplet Splatter Patterns During the COVID-19 Pandemic.

ObjectiveThe otolaryngology community has significant concerns regarding the spread of SARS-CoV-2 through droplet contamination and viral aerosolization during head and neck examinations and procedures. The objective of this study was to investigate the droplet and splatter contamination from common otologic procedures.Study DesignCadaver simulation series.SettingDedicated surgical laboratory.MethodsTwo cadaver heads were prepped via bilateral middle cranial fossa approaches to the tegmen (n = 4). Fluorescein was instilled through a 4-mm burr hole drilled into the middle cranial fossa floor, and presence in the middle ear was confirmed via microscopic ear examination. Myringotomy with ventilation tube placement and mastoidectomy were performed, and the distribution and distance of resulting droplet splatter patterns were systematically evaluated.ResultsThere were no fluorescein droplets or splatter contamination observed in the measured surgical field in any direction after myringotomy and insertion of ventilation tube. Gross contamination from the surgical site to 6 ft was noted after complete mastoidectomy, though, when performed in standard fashion.ConclusionOur results show that there is no droplet generation during myringotomy with ventilation tube placement in an operating room setting. Mastoidectomy, however, showed gross contamination 3 to 6 ft away in all directions measured. Additionally, there was significantly more droplet and splatter generation to the left of the surgeon when measured at 1 and 3 ft as compared with all other measured directions.

The Anterolateral Triangle: Implications for a Transnasal Prelacrimal Approach to the Floor of the Middle Cranial Fossa.

The anterolateral triangle enclosed by the foramen rotundum and foramen ovale constitutes part of the floor of the middle cranial fossa (MCF). 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. 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. 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. It is feasible to access the floor of MCF via an endoscopic transnasal prelacrimal approach with seemingly low risk.

Thinning or dehiscence of bone in structures of the middle cranial fossa floor in superior semicircular canal dehiscence

BackgroundSuperior semicircular canal dehiscence (SSCD) is a rare inner ear disorder; currently, it is unknown whether the etiopathology underlying this structural irregularity affects neighboring structures. The goal is to investigate the prevalence of bone thinning in areas of the middle cranial fossa (MCF) floor in SSCD and non-SSCD patients. MethodsThis retrospective study analyzed 100 patients from March 2011 to June 2017 at a tertiary referral center. 100 patients undergoing 118 SSCD repair surgeries (18 bilateral) were identified. 12 SSCD ears were excluded due to lack of pre-operative computed tomography (CT) scans or history of prior SSCD repair at an outside facility. Non-SSCD ears were identified from routinely-obtained CT scans for temporal bone fracture (fractured sides excluded) for a total of 101 ears; 26 non-SSCD ears were excluded due to lack of high-resolution imaging. ResultsUnivariate analyses reveal that SSCD diagnosis is associated with higher rates of geniculate ganglion (GG) dehiscence compared with non-SSCD controls (42.7 vs. 24%; χ2(1) = 9.69,P = 0.008). Individuals with SSCD depicted significantly thinner bone overlying the geniculate ganglion (GG) (0.23 ± 1.2 mm) compared to controls (0.28 ± 1.8 mm, (t(1 6 4)) = 2.1, P = 0.04). SSCD patients presented thinner bone overlying the internal auditory canal (IAC) (0.33 ± 1.3 mm) compared to patients without SSCD (0.46 ± 1.6 mm, (t(2 5 7) = 6.4, P < 0.001). ConclusionsThe increased prevalence of dehiscence of the MCF in this cohort of SSCD patients compared to non-SSCD patients suggests that the etiology underlying SSCD affects surrounding structures.

A Curious Case of Crystal Deposit Disease in the Petrous Bone

Crystal deposit disease is a rare disorder with benign dense soft tissue calcium containing accumulations presenting as pseudogout or tumoral calcinosis. It rarely affects the head and neck region and even less to the petrous bone. We describe a case of para-articular tumoral calcinosis involving the external auditory canal wall in close proximity to the temporomandibular joint with extension towards the middle cranial fossa floor in a 73-year-old man presenting with otalgia and progressing mixed hearing loss. Subtotal petrosectomy with obliteration of the middle ear and mastoid was done with complete removal of the lesion. We discuss the course, treatment and final pathology with possible explanations for the pathophysiology in this particular case. Although tumoral calcinosis is uncommon, this entity should be considered in the differential diagnosis when an osteogenic temporal lesion is seen on computed tomography or magnetic resonance imaging. The treatment for this benign tumor includes complete excision of the lesion in symptomatic cases. Proper evaluation including anamnesis of the family history and previous trauma as well as serology should be done. The exact etiology and classification of crystal deposit diseases require further study.

Prevalence of Asymptomatic Middle Cranial Fossa Floor Pits and Encephaloceles on MR Imaging.

Temporal lobe encephaloceles are increasingly identified and treated as epileptogenic foci. However, there is relatively scant research on the prevalence of asymptomatic encephaloceles. This study set out to describe the frequency of incidental temporal lobe encephaloceles and middle cranial fossa pits. A retrospective review was completed of high-resolution (≤0.5-mm section thickness) axial T2WI for internal auditory canal protocol imaging. The presence and laterality of middle cranial fossa pits (small bony defects containing CSF) and encephaloceles (brain parenchyma protrusion through osseous defects with or without bony remodeling) were recorded. Electronic medical records of patients with encephaloceles were searched for a history of seizure. A total of 203 patients were included in the final cohort; 106 (52.2%) women. Forty-five (22.2%) patients had middle cranial fossa pits: 14 (31.1%) unilateral on the right, 17 (37.8%) unilateral on the left, and 14 (31.1%) bilateral. Ten (5.0%) patients had ≥1 encephalocele, none of whom had a documented history of seizure in the electronic medical record. No significant difference was noted in the frequency of pits or encephaloceles based on sex (P = .332 and P = .383, respectively) or age (P = .497 and P = .914, respectively). Incidental middle cranial fossa pits are common findings, and their prevalence is not related to age or sex. Temporal lobe encephaloceles, though rarer, also exist occasionally among asymptomatic patients. Such findings have diagnostic implications for encephaloceles identified during imaging work-up for epilepsy.

Morphometric and morphologic study of Foramen Ovale in In Indian population

Background:The floor of middle cranial fossa shows several foramina through which vital neural and vascular structures pass. Thus, the knowledge of normal and variant anatomy of these foramina is important. One such foramen is Foramen ovale which allows the passage of certain important structures.&#x0D; Aims and Objective:This study also aimed to provide a base line data to neurosurgeons for easy and safe approach to middle cranial fossa. Thus, to fulfill the above, the morphometric and morphologic characteristics of the foramenovalewere studied and the observed metric and non-metric parameters were compared with those of previous studies.&#x0D; Materials and Methods:The study has been conducted on 160 adult non-pathological dry human skulls of unknown age and sex. Those parts of broken skulls were included in the study in which the area of Foramen ovale was intact. All the parameters were obtained by one observer only to avoid inter-observer error. The foramen ovale was identified and different metric and non-metric parameters were observed and measured.&#x0D; Results:The most common shape on both sides was noted to be transversely oval. Out of 160 skulls, 2 skulls (1.25%) showed accessory FO bilaterally. 4 skulls showed divided FO on left side. Out of 4, 2 skulls( 1.25%) were noted to have bony bar and in 2 skulls (1.25%) the main FO were divided by bony plate.&#x0D; Conclusion: The morphologic variations of Foramen Ovale in the form of accessory foramen and presence of bony bar / bony plate are common. This study will provide a baseline data as well as frequency of related variations in our population for a safer approach by the surgeons.

Hearing Improvement Following Middle Cranial Fossa Floor Defect Repair Utilizing a Modified Middle Fossa Approach and Reconstructive Techniques.

Few studies report hearing preservation following middle cranial fossa (MCF) floor defect repair. To investigate audiological outcomes following MCF floor defect repair using a modified MCF suprapetrous approach. Retrospective cohort. Tertiary referral center. Eleven patients, with MCF floor defects. MCF floor defect surgical repairs with either fascia or fascia and bone graft. Hearing outcomes. Eleven patients (two men) aged 34 to 82 years (median, 62 yrs) were identified. All patients were operated on by the same two senior surgeons (M.P. and M.G.). One patient with conductive hearing loss (based on tuning fork test) was excluded from the analysis due to missing preoperative audiogram data. All patients had middle fossa plate defects leading to cerebrospinal fluid (CSF) otorrhoea, rhinorrhoea, or meningitis. Nine patients had retrieval of herniated contents from the defect. Five patients had repair with temporalis fascia and split calvarial bone graft, and six patients had repair with fascia only. Follow up audiogram was performed at a mean 7.5 months (range, 0.5-24 mo). There was no recurrent CSF leak during the follow up period. The 10 patients (90.9%, 95% confidence interval [CI] 60.1-100.6) who had complete audiologic data sets demonstrated a mean improvement of 18.86 dB (range, -7.5 to 33.75 dB) in hearing postoperatively. One of these patients acquired a 7.5 dB reduction in postoperative hearing due to post-procedural middle ear effusion which subsequently resolved. Hearing improvement following fascial graft alone versus fascial graft with bone was 12.5 and 26.5 dB, respectively (p < 0.01). Middle fossa craniotomy with or without retrieval of herniated contents and floor reconstruction with fascia and bone is associated with improved hearing. Clinical efficacy of this technique, however, can be only fully established when a statistically meaningful number of cases have been performed.

Thinning or Dehiscence of Bone in Structures of the Middle Cranial Fossa Floor in Superior Semicircular Canal Dehiscence

Thinning or Dehiscence of Bone in Structures of the Middle Cranial Fossa Floor in Superior Semicircular Canal Dehiscence

Endoscopic transorbital superior eyelid approach: anatomical study from a neurosurgical perspective.

OBJECTIVERecent studies have proposed the superior eyelid endoscopic transorbital approach as a new minimally invasive route to access orbital lesions, mostly in otolaryngology and maxillofacial surgeries. The authors undertook this anatomical study in order to contribute a neurosurgical perspective, exploring the anterior and middle cranial fossa areas through this purely endoscopic transorbital trajectory.METHODSAnatomical dissections were performed in 10 human cadaveric heads (20 sides) using 0° and 30° endoscopes. A step-by-step description of the superior eyelid transorbital endoscopic route and surgically oriented classification are provided.RESULTSThe authors' cadaveric prosection of this approach defined 3 modular routes that could be combined. Two corridors using bone removal lateral to the superior and inferior orbital fissures exposed the middle and anterior cranial fossa (lateral orbital corridors to the anterior and middle cranial base) to unveil the temporal pole region, lateral wall of the cavernous sinus, middle cranial fossa floor, and frontobasal area (i.e., orbital and recti gyri of the frontal lobe). Combined, these 2 corridors exposed the lateral aspect of the lesser sphenoid wing with the Sylvian region (combined lateral orbital corridor to the anterior and middle cranial fossa, with lesser sphenoid wing removal). The medial corridor, with extension of bone removal medially to the superior and inferior orbital fissure, afforded exposure of the opticocarotid area (medial orbital corridor to the opticocarotid area).CONCLUSIONSAlong with its minimally invasive nature, the superior eyelid transorbital approach allows good visualization and manipulation of anatomical structures mainly located in the anterior and middle cranial fossae (i.e., lateral to the superior and inferior orbital fissures). The visualization and management of the opticocarotid region medial to the superior orbital fissure are more complex. Further studies are needed to prove clinical applications of this relatively novel surgical pathway.

A Method of Locating the Dehiscence during Middle Fossa Approach for Superior Semicircular Canal Dehiscence Surgery.

Objectives Superior semicircular canal dehiscence (SSCD) results from a defect in the middle cranial fossa floor. One challenge during SSCD repair is the lack of a consistent landmark. This study proposes a reference point above the external auditory canal at the level of the zygoma as the inferior craniectomy edge during surgery. Design This is a retrospective review of patients with SSCD. Setting/Participants A total of 72 cases of SSCD in 60 patients were repaired via a middle fossa approach at a single institution. Main Outcome Measures The distance from the proposed reference point to the dehiscence was statistically analyzed using Shapiro-Wilk's goodness-of-fit test and Student's t -test. Results Average distance for all patients was 28.84 ± 2.22 mm (range: 22.96-33.43). Average distance for females was 29.08 mm (range: 24.56-33.43) versus 28.26 mm (range: 22.96-32.36) for males. There was no difference in distance by sex ( p = 0.174). The distance measurements followed a normal distribution with 95% of the patients between 24.49 and 33.10 mm. Conclusion This study analyzed a potential reference point during a middle fossa approach for SSCD surgery. The distance from this reference point to the SSCD was found to be consistent and may serve as a readily identifiable landmark in localizing the dehiscence.

A morphometric analysis and study of variations of foramina in the floor of the middle cranial fossa

IntroductionThe middle cranial fossa (MCF) in human skulls is characterized by extremely complex architecture and dense crowding of structures traversing the various foramina present in its floor. Despite the numerous variations exhibited by these foramina and their critical importance to neurosurgeons operating in this area, comprehensive accounts of metric and non-metric data on MCF foramina are quite scarce in literature. The present study aims to bridge this gap in knowledge. MethodsFifty well-preserved dry, macerated adult (age >20yrs) skulls were obtained from the Anatomy departments of AIIMS and other medical colleges in Delhi. Each skull was examined for all the MCF foramina and the variations noted. The foramina were digitally photographed for morphometric data with reference to sex and side (left/right) using ImageJ software. ResultsThe data survey revealed numerous individual variations in the metric and/or non-metric characteristics of each MCF foramen. The foramina ovale, rotundum, spinosum & lacerum were found to be consistently present in all 50 skulls whereas some skulls exhibited the foramen of Vesalius (unilateral 17%; bilateral 12%) and canaliculus innominatus (5%). The data on maximum diameter and area tabulated for each foramen revealed significant individual, sex and side variations. DiscussionThe present study found several variations in the shape, size, dimensions, laterality and frequency of foramina present in the MCF floor. The little data existing in literature about these foramina compares well with these findings. The neurosurgical importance of baseline data pertaining to MCF foramina among various ethnic and demographic groups cannot be overstated.

Middle Cranial Fossa Dehiscence as an Incidental Finding on CT.

This retrospective chart review demonstrates that the prevalence of middle cranial fossa (MCF) dehiscence on computed tomography (CT) scans increases with age. High-resolution temporal bone CT scans, which had been obtained for any otologic complaint, were reviewed independent of all clinical history. Scans showing soft tissue, fluid, trauma, or previous operations were excluded. The CTs from 183 patients (296 ears) were reviewed, blinded for age and body mass index (BMI). The MCF floor was divided into 7 regions and systematically inspected. Ages and BMIs of the patients were subsequently extracted from the medical record. Logistic regression analysis confirmed increasing MCF dehiscence with age (P < .05, odds ratio [OR] = 1.07, R = .584). Over all ages (range, 1-88 years; average, 38.5), 32% of MCF floors were dehiscent at any 1 site. For age 60 and over, 55% were dehiscent. The most common sites of MCF dehisence were directly above the malleus head and above the additus ad antrum (35% and 28%, respectively). Superior canal dehiscence (SCD) was seen in 7% of all patients and only in the context of MCF dehiscence. The prevalence of MCF dehiscence increased with age when patients were analyzed by BMI <25, BMI = 25-30, and BMI >30 (P < .003, P < .04, P = .03). The increase of middle cranial fossa dehiscence with respect to age is statistically significant. Over all ages, approximately 32% of ears show dehiscence. Over 60 years, approximately 55% show dehiscence. The odds of having dehiscence double with a 10-year difference in age. The most common sites along the MCF floor are in the epitympanum over the malleus head and the additus ad antrum. There was a statistically significant increase in MCF dehiscence with age when patients with equivalent BMIs are compared.