Vidian canal and sphenoid sinus: an MDCT and cadaveric study of useful landmarks in skull base surgery.

PURPOSE: To present the anatomical variations of vidian canal (VC) and sphenoid sinus (SS), relative to other anatomical landmarks of skull base area, which may be helpful for safer surgical approach to this area. MATERIALS: MDCT scans (128-row MDCT system) of 90 patients (mean age 62 years) and six cadaveric heads were studied, and the following parameters were evaluated: mean length and types of VC, distance between VC and foramen rotundum (FR) and optic canal (OC), position of the VC regarding the lateral pterygoid plate (MPTG) and petrous ICA, pneumatization of SS, position of intrasinus septum regarding ICA and OC, bone dehiscence and protrusion of ICA and OC into SS. Six cadaveric heads underwent MDCT and endoscopic dissection, and the type and length of VC were evaluated. The statistical significance was assessed using Chi-square (χ2) test. Significance level was set at p < 0.05. RESULTS: A statistical analysis was performed between the measurements at both sides, as well as between measurements in MDCT and dissection of the six cadaveric heads. Statistically significant difference was found between right and left sides in the horizontal and vertical distances between FR and VC, as well as between VC and OC. Also, there was a statistically positive correlation between type II of VC and lateral pneumatization on the right side. There was not statistically significant difference concerning VC type and length between MDCT and dissection measurements. CONCLUSION: Surgeons addressing skull base surgery must be familiar with the anatomical and positional variations of VC and SS in the preoperative CT images so as to avoid serious complications during surgery.

Cranial nerve V2 and Vidian nerve trauma secondary to lateral pterygoid recess encephalocele repair.

BACKGROUND: The incidence of adverse sequelae related to trauma of cranial nerve V2 (V2) and the Vidian nerve (VN) during endoscopic pterygoid recess repair (PRR) of lateral sphenoid encephalocele is insufficiently reported in the medical literature. As part of our quality assessment and improvement program we sought to analyze the incidence and severity of V2 and VN injury during a 9-year experience (2010-2018) with PRR. METHODS: Hypoesthesia, paresthesia, and dry eye and their impact on patient quality of life were sought through chart review and a self-reported 0 to 5 Likert scale for each symptom. RESULTS: Thirty-five patients underwent repair of spontaneous cerebrospinal-fluid (CSF) rhinorrhea, with 11 consecutive patients undergoing endoscopic PRR. Mean follow-up for PRR was 32.5 months (range, 2.4 to 103.3 months). Although definitive management resulted in 100% success, 1 required secondary treatment. Eight patients were available for long-term follow-up (72.7%) and completed a symptom severity questionnaire using a Likert-scale. All patients observed either hypoesthesia, paresthesia, or dry eye of varying gradation (scale, 0 to 5). None described disabling symptoms, and some reported gradual improvement. Numbness, paresthesia, and dry eye were reported by 6 of 8 (75%), 5 of 8 (62.5%), and 4 of 8 (50%) patients, respectively. The mean Likert score among the 8 patients who completed this questionnaire noticing hypoesthesia, paresthesia, and dry eye was 2.6, 1.3, and 1.8, respectively. CONCLUSION: Meticulous surgical technique is paramount for successful PRR and minimizing nerve injury, yet the anatomic variation of the lateral pterygoid recess can be challenging, and neural injury is a real risk. Preoperatively, patients should be counseled that although V2 or VN injury is common, most patients describe resulting symptoms to be rarely bothersome.

Growth dynamic of the geniculate ganglion in children: a retrospective computed tomography study.

PURPOSE: The main aim of this retrospective computed tomography (CT) study was to examine the morphometric development of the geniculate ganglion (GG) in children aged between 1 and 18 years for surgical approaches. METHODS: This study was placed on 41 patients (20 females and 21 males) including cochlear implantation cases aged from one to 18 (at mean, 6.44 ± 5.79) years. All the measurements belonging to the length, width and area of GG were performed with a CT scanner. RESULTS: The morphometric values of GG were not different in terms of sex or side, statistically (p > 0.05). The length (p = 0.155) of GG was not correlated with the increasing ages from one to 18 years; however, its area (p < 0.001) and width (p = 0.003) were found to be increased in the childhood period. Linear functions for the length, width and area of GG were calculated as y = 2.028 + 0.011 × age (years), y = 1.496 + 0.014 × age (years), and y = 3.239 + 0.035 × Age (years), respectively. The dehiscence of GG was found in 22 (26.8%) out of 82 temporal bones. CONCLUSION: Our data suggested that the area and width of GG were progressively increasing with age in the childhood period. The calculated formula representing the growth dynamic of GG in children and the incidence of the presence of the dehiscent GG can be useful for radiologists and otologists to estimate its size and to avoid iatrogenic injury during early childhood surgeries.

Accuracy of high-resolution computed tomography in revealing fallopian canal fracture of patients with traumatic facial paralysis.

OBJECTIVES: To investigate accuracy of high-resolution computed tomography (HRCT) of temporal bone in revealing fallopian canal fracture among the patients with traumatic facial paralysis. METHODS: HRCT of temporal bone with cross-sectional scanning and multi-planar reformation (MPR) was performed on 31 patients with traumatic facial paralysis, and fracture sites of fallopian canal revealed by HRCT were retrospectively analyzed and compared with surgical findings. RESULTS: HRCT of temporal bone showed fracture of fallopian canal at geniculate ganglion in 25 cases, at tympanic segment in 15 cases, at labyrinthine segment in 5 cases, at pyramid segment in 2 cases, and at mastoid segment in one case, while surgical findings revealed that fracture involved geniculate ganglion in 27 cases, labyrinthine segment in 5, tympanic segment in 19, pyramid segment in 12, and mastoid segment in 9; the sensitivity of HRCT of temporal bone to detect fracture at such sites was 88.9%, 100%, 52.6%, 16.7% and 11.1%, respectively, and the specificity was 96.0%, 100%, 66.7%, 100% and 100%, respectively. CONCLUSION: HRCT of temporal bone was able to accurately reveal fracture of fallopian canal at geniculate ganglion and labyrinthine segment in the vast majority cases, but severely underestimated fracture at pyramid segment and mastoid segment of fallopian canal.

Results of decompression with middle cranial fossa approach or traumatic intratemporal fascial nerve injury.

OBJECTIVE: To present the results of the traumatic intratemporal facial nerve injury that have undergone facial nerve decompression by using middle cranial fossa (MCF) approach. STUDY DESIGN: A retrospective study SETTING: Tertiary referral center PATIENTS AND METHODS: In this study, 13 patients who developed facial paralysis due to temporal bone trauma and undergone decompression by using MCF approach in Department of Otorhinolaryngology of Izmir Katip Celebi University Research and Training Hospital between January 1993 and December 2012 were presented retrospectively. Patients were assessed in terms of side, etiology, fracture type, House-Brackmann (HB) grade, electroneuronography (ENOG), electromyography (EMG), hearing loss, operation time, and the region of the injury. RESULTS: The fracture was at the right side in 7 (53.8%) and at the left side in 6 patients (46.1%). The type of temporal bone fracture was longitudinal in 6 (46.1%), transverse in 2 (15.3%), and mixed in 5 patients (38.4%). Total axonal degeneration in EMG and ENOG were seen in all patients, who were HB grade 6 at preoperative assessment. Mean operation time was 30 days. The lesion in all patients was at the region of geniculate ganglion. There was conductive hearing loss in 7 patients (53.8%), sensorineural in 4 (30.7%), and mixed in 1 patient (7.6%); hearing was normal in 1 patient (7.6%). Seven patients (53.8%) improved to HB grade 2. CONCLUSION: In the light of the information obtained from HRCT, ENOG, and EMG, we believe that better results can be achieved with facial nerve decompression that is performed before 1 month, and geniculate ganglion region may be better controlled by MCF approach.

Trans-tensor tympani facial nerve decompression in traumatic facial nerve palsy.

OBJECTIVE: The surgical approaches previously reported for facial nerve decompression have focussed on achieving good exposure of the lateral or superior aspects of the geniculate ganglion. This report aims to describe a unique case of facial nerve decompression beneath the geniculate ganglion. PATIENT: A 30-year-old woman with right-sided facial palsy due to a temporal bone fracture. INTERVENTION: Bony fragments at the base of the geniculate ganglion were removed via a trans-tensor tympani approach with extended posterior tympanotomy. RESULTS: The patient's facial movement recovered successfully, without complications such as sensorineural hearing loss and conductive hearing loss. CONCLUSION: In rare cases requiring decompression of the facial nerve inferior to the perigeniculate area, the trans-tensor tympani approach should be considered as a valuable alternative option when surgical intervention is considered.

Enlarged geniculate ganglion fossa: CT sign of facial nerve canal fracture.

RATIONALE AND OBJECTIVES: The aim of this study was to preliminarily investigate whether an enlarged geniculate ganglion fossa (GGF) on temporal bone computed tomography can diagnose GGF fracture in patients with traumatic facial paralysis by evaluating the diameter of the GGF. MATERIALS AND METHODS: Thirty-six patients who underwent computed tomography before confirmation of GGF fracture on otologic surgery were recruited into a study group. Additionally, a cohort of 107 patients with no histories of head trauma, no structural abnormalities of inner ear, and no clinical symptoms of facial nerve disability who underwent computed tomography for other reasons were selected as a control group. The diameters of the GGFs of the study group were evaluated by two observers and compared retrospectively with those of the control group. Wilcoxon's test was used to compare discrepancies of both sides, and intraclass correlation coefficients were used to evaluate intraobserver and interobserver reliability. RESULTS: The measurement of diameters showed good interobserver and intraobserver consistency. The discrepancy in the measurement of transdiameter between both sides of the GGF on reformatted transverse images of the study group was significantly different from that of the control group (Wilcoxon's test, P < .001). Discrepancy in the GGF on transverse images of the study group was larger than that of the control group. A significant difference existed in the discrepancy in vertical diameter between the study and control groups (Wilcoxon's test, P < .001) as well. CONCLUSIONS: An enlarged GGF on temporal bone computed tomography offers an additional sign for the diagnosis of GGF fracture in patients with traumatic facial paralysis.

Infranuclear facial palsy: importance of imaging the geniculate fossa.

OBJECTIVE: To highlight the importance of imaging the geniculate fossa in patients with solitary infranuclear facial palsy. STUDY DESIGN: Prospective. SETTING: Tertiary referral center. ELIGIBILITY CRITERIA: Patients with solitary infranuclear facial palsy sent for imaging. INTERVENTION: Diagnostic. MAIN OUTCOME MEASURE: Imaging specifics concerning high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) are described in detail for evaluation of the intratemporal part of the facial nerve with special focus on the geniculate fossa. RESULTS: Normal appearances of the geniculate fossa on HRCT and MRI and its normal anatomic variant, that is, dehiscence of the overlying bone are described. Imaging findings in a range of pathologies involving the geniculate fossa in a clinical setting of infranuclear facial nerve palsy is demonstrated. These include infections (tuberculosis), trauma, schwannoma, hemangioma, meningioma, and perineural spread of parotid malignancy. CONCLUSION: The geniculate fossa is a small bony hiatus in the temporal bone and is situated at the junction of the labyrinthine and the tympanic segments of the intratemporal facial nerve canal. It houses important neural structures and is best visualized by a combination of HRCT and high-resolution MRI examination of the temporal bone. It is therefore imperative for imaging specialists to be familiar with the normal appearance of this structure on HRCT and MRI examinations of the temporal bone as subtle imaging findings involving the geniculate fossa can be indicators of a variety of abnormalities.

Facial nerve paralysis in temporal bone fractures: outcomes after late decompression surgery.

The aim of this paper was to address some of the unanswered questions regarding management of facial nerve paralysis in temporal bone fractures (TBF), such as the outcomes after late facial nerve decompression surgery. The study design was a retrospective review of a consecutive clinical series. Thirteen patients who underwent late decompression surgery for facial nerve paralysis due to TBF involving the perigeniculate ganglion region were analyzed. Patients were operated on 27-90 days after trauma. A transmastoid extralabyrinthine approach was used in all cases. Facial nerve-sheath slitting was performed routinely. Normal or subnormal facial nerve function (HB 1 or HB 2) was achieved in 7/9 cases (78%) evaluated at > or = 1 year after surgery. Good functional results were also obtained in two patients operated on 3 months after trauma. Bases on the outcomes observed in the present series, in patients unable to be operated on early, presenting 1 to 3 months with >95% denervation on EnoG, facial nerve decompression may have a beneficial effect.

Temporal bone fractures.

High-resolution technique is essential to the evolution of temporal bone fractures. Axial and coronal scan planes are optimal but may not be possible in acutely traumatized patients. A knowledge of normal temporal bone anatomy is important and can be obtained from standard texts, so it will not be considered in detail in this article. Classically, petrous temporal bone fractures have been classified as longitudinal, transverse, or mixed. Recent publications have emphasized the importance of describing fractures in terms of planes rather than lines. According to this concept, most temporal bone fractures are actually oblique, and true longitudinal fractures are rare. Petrous temporal bone fractures may be associated with cranial nerve or vascular injuries when the fracture extends to the skull base. This is particularly true of the oblique fracture, which characteristically extends anteromedially to the skull base through weak places in that area, thus avoiding the compact bone of the otic capsule surrounding the labyrinth. The most common associated injury is to the facial nerve in its geniculate or proximal tympanic segment. Transverse fractures frequently involve the labyrinth. A careful search for various types of ossicular dislocation should be performed in association with temporal bone fractures, because this may result in conductive hearing loss. The site of cerebrospinal fluid otorhinorrhea resulting from temporal bone fractures can usually be defined on plain high-resolution temporal bone images, but intrathecal contrast may be helpful. Temporal bone fractures caused by gunshot wounds are frequently complex and may be limited by metallic streak artifacts. Pediatric patients have different proportions of facial nerve injury and types of hearing loss as compared with adults.

Contrast-enhanced MR of the facial nerve in patients with posttraumatic peripheral facial nerve palsy.

PURPOSE: To estimate the value of noncontrast and contrast-enhanced T1-weighted MR imaging in detecting the underlying mechanisms of injury and regeneration in immediate- or delayed-onset posttraumatic peripheral facial nerve palsy. METHODS: Twenty-four patients with posttraumatic peripheral facial nerve palsy were examined on a 1.5-T MR imaging unit with precontrast and postcontrast T1-weighted spin-echo and gradient-echo sequences. RESULTS: Abnormal enhancement of the distal intrameatal nerve segment was visible in 92% of the patients up to 2 years after their initial trauma. A hematoma within the geniculate ganglion was seen in 33% of the patients with a longitudinal fracture. The greater superficial petrosal nerve (in 32% of patients) and the geniculate ganglion (in 48% of patients) were thick and intensely enhancing. Hematoma within the cochlea/vestibule or enhancement of the cochlea/vestibule and the vestibulocochlear (eighth) nerve was observed in transverse fractures. CONCLUSION: MR images can show long-lasting abnormal nerve enhancement, especially in the distal intrameatal nerve segment, related to the long-lasting breakdown of the blood/peripheral nerve barrier associated with nerve degeneration and regeneration after traumatic stretching of the greater superficial petrosal nerve. Additionally, intraoperatively observed perineural and intraneural scar formation leads to thickening and intense enhancement of the affected nerve segments on MR images. A hematoma in the region of the geniculate ganglion can be seen in some but not all patients. Associated damage of the inner ear structures in patients with transverse fractures is also visible on MR images.

Facial paralysis in longitudinal temporal bone fractures: a review of 26 cases.

The management of facial nerve injury resulting from temporal bone fracture continues to be a topic of discussion. The indications for surgery as well as the proper timing and extent of surgical exploration are the principal questions debated. This study reviews a large series of patients (26), treated for facial paralysis following a longitudinal temporal bone fracture. The most frequent site of injury was the area of the geniculate ganglion. The injury to the facial nerve was often severe. We recommend early exploration in these cases when electrical studies indicate a severe injury. In most cases a combined mastoid and middle fossa approach is required.

[Trauma of the facial nerve at the geniculate ganglion (author's transl)]. / Fazialistraumen am Ganglion geniculi.

Fractures of the pyramid, longitudinal fractures in the majority of cases, lead to a damage of the facial nerve in the surrounding of the geniculate ganglion. This area has to be controlled surgically when a facial nerve paralysis occurs after a head injury.