Labyrinthine Segment Research Articles

Subtotal facial nerve decompression for recurrent facial palsy in Melkersson Rosenthal syndrome

Conclusions: Subtotal facial nerve decompression seems effective to prevent further episodes of facial palsy and promote facial nerve recovery for recurrent facial palsy in Melkersson Rosenthal syndrome (MRS). The main inflammatory sites of recurrent facial palsy in MRS may be the mastoid segment, tympanic segment, geniculate ganglion, and labyrinthine segment. Objective: To present our surgical experience in preventing further episodes of facial palsy and improving facial nerve recovery of patients with recurrent facial palsy in MRS. Methods: We performed transmastoid subtotal facial nerve decompression on eight patients with recurrent facial palsy in MRS. They were followed up for 3.3 years on average (range 2–5 years). Results: There were no further attacks of facial palsy in any of the cases. Seven cases (87.5%) recovered to grade I or grade II, and three of eight cases (37.5%) recovered completely. We found obvious edema of the facial nerve at the mastoid segment in all cases, at the tympanic segment and geniculate ganglion in five cases (62.5%), and at the labyrinthine segment in only one case (12.5%).

Surgical findings to differentiate between facial nerve schwannoma and vestibular schwannoma.

ObjectivesFacial nerve schwannomas may be misdiagnosed as vestibular schwannomas (VSs) if the tumor is confined to the internal auditory canal (IAC) without involvement the geniculated ganglion or labyrinthine segment of facial nerve. Because facial nerve schwannomas may be misdiagnosed as VSs, we investigated the differences between the two.MethodsThe study included 187 patients with a preoperative diagnosis of VS. Of these, six were diagnosed with facial nerve schwannomas during surgery. We reviewed the preoperative evaluations and surgical findings of facial nerve schwannomas mimicking VSs.ResultsNo useful preoperative predictors are available for facial nerve schwannomas mimicking VSs. Facial nerve schwannomas are usually confined to the IAC. After opening the dura of the IAC, a facial nerve schwannoma can be diagnosed after identifying a normal-appearing nerve located lateral to the tumor. When this was the case, we performed facial nerve preservation surgery or decompression.ConclusionFacial nerve schwannomas can be differentiated from VSs by identifying specific findings during surgery.

Facial nerve: From anatomy to pathology

The facial nerve (CN VII) emerges from the facial nerve nucleus in the pons. It is accompanied by CN VIII along its cisternal pathway, as well as at the internal auditory meatus. Its petrous pathway includes a labyrinthine segment, a horizontal tympanic segment and a vertical mastoid segment until the stylomastoid foramen. It then continues to the parotid gland. Pontine impairment is usually associated with other neurological symptoms. Lesions of the cerebellopontine angle (most often meningioma and schwannoma) initially result in impairment of CN VIII. The impairment of CN VII takes second place. Peripheral impairment (outside of a traumatic context) is most often due to Bell's palsy.

Clinical analysis of nine cases of congenital petrous apex cholesteatoma

To investigate the clinical symptoms, diagnosis and treatment of congenital petrous apex cholesteatoma. A retrospective review of clinical symptoms, image findings and effect of operation in nine patients with congenital petrous apex cholesteatoma were performed. two cases of congenital petrous apex cholesteatoma patients had peripheral facial paralysis, and progressively aggravated;four cases of peripheral facial paralysis were repeated, without hearing loss; three cases firstly appeared hearing loss, followed by paralysis. When hospitalized, nine cases of patients had peripheral facial paralysis and hearing loss. Seven patients were complicated with tinnitus, and four had vertigo. HRCT scans showed petrosal apex damage; MRI showed that petrosal apex was occupied;and the facial nerve electromyography and evoked potential examination showed moderate-severe neurogenic changes. All were treated by surgeries, among them, 8 cases were by middle fossa approach, 1 case was by middle cranial fossa-translabyrinth combined approach. Two cases whose labyrinthine segment of the facial nerve injured severely, were operated by end to end anastomosis; 3 cases with facial nerve compression thinning, were operated by facial nerve decompression; 4 cases were horizontal segment of facial nerve exposed and edema. None of them had recurrence in a follow-up of 6 to 32 months. 3 cases of peripheral facial paralysis were lessened in different degrees. Patients with congenital petrous apex cholesteatoma have peripheral facial paralysis in the early stage. Computed tomography scanning, magnetic resonance imaging and facial nerve imaging has important significance to clinical diagnosis, choosing the approach of operation and dealing with the facial nerve during operation.

Fibrous Dysplasia of the Temporal Bone: Imaging Characteristics and Neurotologic Considerations

Introduction: Fibrous dysplasia (FD) is a progressive, often indolent bone disorder in which normal bone marrow is replaced by a mixture of fibrous tissue and woven bone. It can potentially involve the long bones, pelvis, and craniofacial bones, either as monostotic or polyostotic disease. FD of the skull most commonly involves the frontal and sphenoid bones. Isolated FD of the temporal bone is relatively rare. Case Report: A 15-year-old boy presented with several weeks of progressive left-sided headaches. He was neurologically intact including facial nerve, hearing, and vestibular examinations. Imaging revealed an extradural left middle fossa lesion appearing to arise from the bones of the inner ear. Temporal bone CT demonstrated that the lesion abutted the geniculate ganglion, the labyrinthine and tympanic segments of CN VII, the superior semicircular canal, and the petrous carotid. The patient was taken to surgery, where radical resection was limited by proximity to the facial nerve, which was adjacent to the field but not compressed. The diagnosis of FD was confirmed by pathology. Postoperatively, the patient developed a delayed House-Brackmann 3 facial droop which was self-limited. Discussion: The etiology of FD is a somatic missense mutation in the gene GNAS1, which encodes the alpha subunit of the stimulatory G protein-coupled receptor Gsα. The mutation leads to constitutive, ligand-independent activation and accumulation of cAMP, similar to the effect of continuous parathyroid hormone stimulation. Studies of the natural history of FD have suggested that the disease becomes inactive after puberty, although as many as one third of patients have recurrence in adulthood. Postpubertal disease progression is observed more commonly in the polyostotic rather than the monostotic disease variant. The incidence of malignant transformation is reported at 0.4%, although sarcomatous transformation has been strongly associated with radiation treatment. Radiologically, three patterns of FD have been described: pagetoid (ground-glass), the most common; sclerotic; and cystic, the least common (10% of cases) and of which the present case is an example. Retroauricular swelling and hearing disturbances are the most common presenting complaints in patients with temporal bone FD. A recent temporal bone FD case series reported eight of nine patients presenting with conductive or sensorineural hearing loss. Radical excision is generally recommended when technically and cosmetically feasible to minimize the risk of disease recurrence. Recurrence rates of 25% have been reported for subtotal resection. Conclusions: Temporal bone fibrous dysplasia can involve the vestibular apparatus, organs of hearing, and the cranial nerve VII-VIII complex. Delayed facial nerve palsy after decompression can have a favorable prognosis. Radical resection may not be necessary for a good outcome.

Facial canal bifurcation with inner ear anomalies in a case of Klippel–Feil syndrome: A case report

We present a case of Klippel–Feil syndrome in a 2-year-old Chinese girl who presented with global developmental delay and bilateral profound hearing loss. High resolution computed tomography (HRCT) of temporal bones showed bilateral common cavity malformations with hypoplastic internal auditory canals and anomalous labyrinthine segments of both facial canals. The labyrinthine segment of the right facial canal was duplicated. Her brain magnetic resonance imaging (MRI) showed aplasia of both vestibulocochlear nerves, while the cisternal and intracanalicular segments of both facial nerves were of normal caliber. These congenital anomalies, coupled with global developmental delay, precluded her candidacy for cochlear implantation. This case report is aimed at highlighting the association of inner ear malformations and in particular facial canal anomalies in Klippel–Feil syndrome.

Congenital duplication of mastoid segment of facial nerve: A rare case report

Congenital duplication of facial nerve is a very rare anomaly commonly associated with inner and middle ear anomalies. There can be duplication of mastoid, tympanic, or labyrinthine segments. We describe duplication of mastoid segment of facial nerve in a young female who also showed middle ear anomalies and external auditory canal atresia.

The facial nerve canal in patients with Bell’s palsy: an investigation by high-resolution computed tomography with multiplanar reconstruction

Facial nerve edema is an important finding in Bell's palsy patients. Inflammation may cause facial nerve edema, and mechanical compression and ischemic change of the facial nerve may occur in the facial nerve canal. A few studies have reported the dimensions of the facial nerve canal using conventional computed tomography or human temporal bone sections. However, the cross-sectional area of the facial nerve canal has not been fully understood. Therefore, the cross-sectional area of the facial nerve canal was measured in patients with unilateral Bell's palsy by computer tomography with multiplanar reconstruction. Sixteen patients with unilateral Bell's palsy were enrolled. Computed tomography of the temporal bone was performed, and perpendicular images to the facial nerve canal were reconstructed by the multiplanar reconstruction technique. The cross-sectional area of the facial nerve canal on the affected and unaffected sides was measured at the labyrinthine segment, the horizontal segment, and the mastoid segment. Both in the labyrinthine and horizontal segments, the mean cross-sectional area of the facial nerve canal was significantly smaller on the affected side than on the unaffected side. There was no significant difference between the affected and unaffected sides in the cross-sectional area of the facial nerve canal in the mastoid segment. The labyrinthine segment was the narrowest segment in the facial nerve canal. These findings suggest that the facial nerve is vulnerable, especially in the labyrinthine segment of the facial nerve canal, and a narrow facial nerve canal may be one of the risk factors for Bell's palsy.

Skull base CT: normative values for size and symmetry of the facial nerve canal, foramen ovale, pterygoid canal, and foramen rotundum

Contrast-enhanced MRI is the mainstay for detecting pathology in the skull base foramina and nerve canals, through demonstration of abnormal enhancement. When MRI is contraindicated, or unable to differentiate tumor from non-neoplastic pathology, high-resolution skull base CT is indicated to assess for nerve canal or foramen widening, which is currently determined subjectively. The purpose of this study is to provide objective CT criteria that may help distinguish between normal asymmetry and pathologic nerve canal or foramen widening. Temporal bone CTs of 50 consecutive adults without facial or trigeminal nerve pathology were retrospectively reviewed. Short axis measurements were obtained in the axial plane for three segments of the facial nerve canal (labyrinthine, tympanic, and mastoid), foramen ovale, pterygoid canal and foramen rotundum on both sides in each subject. Descriptive statistics were obtained, and left-right asymmetry was calculated. Nerve canal/foramen size was normally distributed across subjects, with a minimal amount of left-right asymmetry. The upper limits of the 95% confidence interval for absolute left-right asymmetry were: 0.25, 0.21, and 0.15mm for the labyrinthine, tympanic, and mastoid segments of the facial nerve canal, respectively; 0.62mm for foramen ovale; 0.36mm for pterygoid canal; 0.38mm for foramen rotundum. Relative asymmetry is more important than absolute size for determining nerve canal/foramen abnormality. These normative data may be useful adjuncts to subjective assessments of nerve canal/foramen size when using skull base CT to identify tumor.

Combined Subtemporal–Supralabyrinthine Approach to Geniculate Ganglion for Management of Facial Paralysis in Temporal Bone Fracture

ObjectiveTo investigate the clinical outcomes of facial never decompression via a combined subtemporal–supralabyrinthine approach to geniculate ganglion for management of facial paralysis in temporal bone fracture. MethodsEighteen patients with unilateral facial paresis due to temporal bone fracture were treated between March 2003 and March 2011. Facial function was House–Brackmann(HB) grade III in 6 patients, HB grade V in 9 patients and HB grade VI in 3 patients. The preoperative mean air conduction threshold was 52 dB HL for the 15 cases with longitudinal temporal bone fracture and showed severe sensorineural hearing loss in the 3 cases with transverse temporal bone fracture. Fracture lines were detected in 15 cases on temporal bone axial CT scans and ossicular disruption was determined in 11 cases by virtual CT endoscopy. The geniculate ganglion or the tympanic mastoid segment of the facial nerve showed an irregular morphology on curved planar reformation images of the facial nerve canal. After an intact canal wall mastoido–epitympanectomy, the ossicular chain damage was evaluated. If the ossicular chain was intact, the supralabyrinthine recess was opened by drilling through the cells between the tegmen tympani and ossicular chain. If the ossicular chain was disrupted, the incus was removed to access the supralabyrinthine recess. The geniculate ganglion and the distal labyrinthine segment of the facial nerve were exposed. After completing facial nerve decompression, the dislocated incus was replaced, or a fractured incus was reshaped to bridge the space between the malleus and the stapes. ResultsPronounced ganglion geniculatum swelling was found in 15 cases of longitudinal temporal bone fracture, with greater petrosus nerves damage in 3 cases and bleeding in 5 cases. Disrupted ossicular chains were seen in 11 cases, including dislocated incus resulting in crushing of the horizontal portion of the facial nerve in 3 cases and fracture of the incus long process in 1 case. In 3 cases of transverse fractures, dehiscence on the promontory, semicircular canal or oval window was found. All cases had primary healing with no complication. At follow–ups ranging from 0.5 to 3 years (average 1.2 years) , facial nerve function recovered to HB grade I in 11 cases, II in 5 cases and III in 2 cases. Overall hearing recovery was 33 dB. ConclusionThe clinical outcomes concerning facial nerve function and hearing recovery are satisfactory via a combined subtemporal–supralabyrinthine approach to the geniculate ganglion for facial nerve decompression in temporal bone fracture patients with facial paralysis.

Use of Computed Tomography to Predict the Possibility of Exposure of the First Genu of the Facial Nerve Via the Transmastoid Approach

The purpose of this study was to investigate whether computed tomography (CT) could predict the possibility of first genu exposure of the facial nerve via the transmastoid approach in patients with acute facial paralysis. Temporal bone CT is the best method for visualizing the intratemporal segment of the facial nerve canal, which is known to have diverse anatomic variations. A prospective study was conducted on 11 patients who underwent facial nerve decompression via the transmastoid approach. Two groups of patients underwent surgery to expose the perigeniculate area via the transmastoid approach. One group included patients who had anatomic parameters of the temporal bone that met the CT criteria, including length of the labyrinthine segment, level of the geniculate ganglion, bony thickness of the lateral semicircular canal, and height interval between the tympanic and labyrinthine segments. The other group included patients with facial paralysis who required facial nerve exploration, especially distal to the geniculate ganglion. Facial nerve decompression was performed in all patients as far proximal in the transmastoid view as was possible without causing damage to the semicircular canals. We correlated the temporal bone CT images and surgical findings in 11 patients who underwent facial nerve decompression via the transmastoid approach. The facial nerves of 6 patients who had anatomic structures that met the CT criteria were successfully exposed to the proximal labyrinthine segment without labyrinthine damage. The facial nerves of another 4 patients who did not have anatomic structures that met the CT criteria could be decompressed only to the geniculate ganglion. CT scan can predict the possibility of first genu exposure of the facial nerve via the transmastoid approach based on the CT parameters suggested in this study.

Anatomical consideration of the temporal bone as a pathogenesis of Bell’s palsy

Much controversy surrounds the etiology and management of Bell’s palsy, and the pathogenetic mechanisms underlying Bell’s palsy remain obscure despite the extensive body of relevant research. The pathological condition of Bell’s palsy is almost an inflammatory reaction compressing the facial nerve in the fallopian canal, particularly in the narrowest labyrinthine segment, followed by demyelinating neural change. As one of the best method for the visualization of the inflamed facial nerve in the intratemporal segment, temporal bone CT enable us not only to measure the exact length and thickness of individual segments of the facial nerve canal but also to view variable anatomic variations in the intratemporal facial canal. Some suggest that anatomical variation may predispose the nerve to inflammatory processes and also there can be peculiar structures of the temporal bone that are vulnerable to inflammation or neural compression injury.

Case 171: Facial Nerve Hemangioma

The patient’s imaging features, especially the honeycomb pattern of ossific changes in the geniculate fossa, were virtually pathognomonic for ossifying hemangioma of the facial nerve.

Middle Skull Base Approach With Posterolateral Mobilization of the Geniculate Ganglion to Access the Clival Regions

Clival lesions remain one of the most challenging intracranial tumors to treat surgically. Many skull base approaches have been described to improve resection and to decrease patient morbidity. To describe a middle skull base approach with posterolateral mobilization of the geniculate ganglion of the facial nerve to access the clival regions. Three patients with petroclival chordoma and 1 patient with petroclival meningioma underwent surgical resection of lesions with our new procedure. Surgical techniques consisted of temporal craniotomy and exposure of the facial nerve from the tympanic segment to the labyrinthine segment, keeping the fundus of the internal auditory canal intact. The geniculate ganglion was mobilized posterolaterally, followed by drilling of the cochlea and exposure of the Dorello canal. Four lesions were successfully removed with complete preservation of facial nerve function. This approach is a modification of the Goel procedure in which the facial nerve from the tympanic segment to the cisternal segment was totally mobilized. Our procedure carries less risk to the facial nerve function than the Goel procedure and provides sufficiently wide exposure of clival lesions.

Recurrent facial nerve palsy: the role of surgery

Repeated episodes of acute idiopathic facial paralysis present both a diagnostic and a management dilemma. We discuss these issues with reference to four adult cases managed between 1999 and 2008, thus adding to the sparse literature on this subject. For such cases, our unit performs decompression of geniculate, labyrinthine and meatal segments of the facial nerve via a middle fossa approach. A short video, available on The Journal of Laryngology & Otology website, demonstrates the key stages of the operation. We believe there is a role for surgical decompression in cases of recurrent acute facial weakness with three or more documented episodes, especially in the presence of progressive deterioration in function. Decompression of the geniculate, labyrinthine and meatal segments, via a middle fossa approach, is our favoured technique, and has achieved good results.

Is the width of the labyrinthine portion of the fallopian tube implicated in the pathophysiology of Bell's palsy?: A prospective clinical study using computed tomography

The pathogenetic mechanisms underlying Bell's palsy remain obscure, despite the extensive relevant research. Magnetic resonance imaging (MRI) studies have strongly indicated that facial nerve edema cannot be regarded as the sole etiologic factor, because it might persist long after full clinical recovery, or might be demonstrated in the clinically unaffected side or healthy controls. The aim of this study was to investigate the hypothesis that a narrow facial canal might be implicated in the pathophysiology of Bell's palsy. Prospective clinical study. A high-resolution computerized tomography of the temporal bone with 1-mm thick contiguous axial sections was performed in 25 patients with unilateral Bell's palsy. The width of the fallopian tube was measured at the meatal foramen and the middle part of its labyrinthine segment. When using paired Student t tests, the measured width of the affected ear was found significantly smaller than that of the unaffected side, both at the meatal foramen (P = .007) and at the middle part of the labyrinthine segment (P = .03). Bell's palsy seems to usually coincide with the narrower fallopian tube of the patient. This anatomical detail, supported by previous MRI studies, seems to indicate that an asymmetry between the right and left fallopian tube might be a necessary pathogenetic mechanism for the development of a facial nerve edema into Bell's palsy in the narrower fallopian canal. More studies on large healthy populations are needed before a notable facial canal asymmetry is linked to a higher risk for developing Bell's palsy.

Enhancement pattern of the normal facial nerve at 3.0 T temporal MRI.

The purpose of this study was to evaluate the enhancement pattern of the normal facial nerve at 3.0 T temporal MRI. We reviewed the medical records of 20 patients and evaluated 40 clinically normal facial nerves demonstrated by 3.0 T temporal MRI. The grade of enhancement of the facial nerve was visually scaled from 0 to 3. The patients comprised 11 men and 9 women, and the mean age was 39.7 years. The reasons for the MRI were sudden hearing loss (11 patients), Méniàre's disease (6) and tinnitus (7). Temporal MR scans were obtained by fluid-attenuated inversion-recovery (FLAIR) and diffusion-weighted imaging of the brain; three-dimensional (3D) fast imaging employing steady-state acquisition (FIESTA) images of the temporal bone with a 0.77 mm thickness, and pre-contrast and contrast-enhanced 3D spoiled gradient record acquisition in the steady state (SPGR) of the temporal bone with a 1 mm thickness, were obtained with 3.0 T MR scanning. 40 nerves (100%) were visibly enhanced along at least one segment of the facial nerve. The enhanced segments included the geniculate ganglion (77.5%), tympanic segment (37.5%) and mastoid segment (100%). Even the facial nerve in the internal auditory canal (15%) and labyrinthine segments (5%) showed mild enhancement. The use of high-resolution, high signal-to-noise ratio (with 3 T MRI), thin-section contrast-enhanced 3D SPGR sequences showed enhancement of the normal facial nerve along the whole course of the nerve; however, only mild enhancement was observed in areas associated with acute neuritis, namely the canalicular and labyrinthine segment.

Correlation between enhanced MRI and surgical findings in herpes zoster oticus

Conclusion: This study demonstrates good correlation between enhanced MRI and surgical findings. Objectives: This study investigated the reliability of enhanced magnetic resonance imaging (MRI) to make a surgical decision on the strategy for facial nerve decompression in herpes zoster oticus, by determining the degree of correlation between contrast enhancement in MRI and the pathologic change in the facial nerve. Subjects and methods: This retrospective study of 13 patients, who underwent facial nerve decompression with herpes zoster oticus, was designed to compare gadolinium-enhanced segment of facial nerve on MRI and the pathologically changed segment confirmed by surgical exploration, grouping them by the timing of operation after onset of facial paralysis. Results: Commonly enhanced segments on MRI were the labyrinthine, intracanalicular, and geniculate ganglion, found in 84%, 69%, and 69% of all patients, respectively. The most common pathologic segment was the labyrinthine segment (92%), followed by the geniculate ganglion (84%).

S230 – MRI Findings in Delayed Facial Palsy after Stapedectomy

Objectives 1) To retrospectively review the pathophysiology and radiologic features of delayed facial palsy after stapedectomy. 2) To discuss the management strategy of this unusual problem. Methods 450 stapedectomies performed at our institution were retrospectively reviewed from 1997 to 2007. A total of 2 patients in this series developed a delayed facial paralysis postoperatively. The clinical presentation, radiographic characteristics on magnetic resonance imaging (MRI), and the management of these patients are presented. Results A total of 2 patients out of 450 stapedectomies within a 10-year period developed the rare complication of delayed facial paralysis (postoperative days 12 and 41, respectively). Both patients developed rapidly progressive complete facial nerve paralysis preceded by periauricular pain and dysguesia. No sign of infection was present in the operated ear. MRI with gadolinium of the internal auditory canal demonstrated gadolinium enhancement of the labyrinthine portion of the facial nerve as seen in Bell's palsy. Both patients were treated with oral corticosteroids and antiviral medications. Subsequent imaging revealed decreased enhancement of the facial nerve with complete resolution of facial paralysis. Conclusions In the rare complication of delayed facial paralysis after stapedectomy, MR imaging is a useful diagnostic tool to dictate the treatment strategy. Delayed facial paralysis following stapedectomy can be treated medically when the MRI scan demonstrates enhancement of the facial nerve in the labyrinthine segment.

Using the processus cochleariformis as a multipurpose landmark in middle cranial fossa surgery

To demonstrate that the anatomical structure known as the processus cochleariformis, with its intimate and constant relationships to inner-ear structures, can be used as a reliable landmark during middle cranial fossa surgery, alone or in conjunction with other landmarks. An anatomical study using cadaveric temporal bones to define six reproducible measurements that relate the processus cochleariformis to inner-ear structures, and to define 14 other measurements that relate inner-ear structures to adjacent structures within the intact bone. Using 10 cadaver specimens, 20 reproducible measurements were defined. The first six of these defined the relation of the processus cochleariformis to inner-ear structures in the middle cranial fossa approach. The other measurements defined the exact location of the inner-ear structures and adjacent structures within the intact bone. The vertical crest lies at a 20 degrees angle from the processus cochleariformis to the coronal plane, and at a distance of 5 to 6 mm from the processus cochleariformis. The point at which the medial margin of the basal turn of the cochlea crosses the labyrinthine segment of the facial nerve lies at a 0 degrees angle from the processus cochleariformis to the coronal plane, and at a distance of 6.5 to 7.5 mm from the processus cochleariformis. The superior semicircular canal lies at a 45 degrees angle from the processus cochleariformis to the coronal plane. The other measurements obtained give important clues about the position of the cochlea, vestibulum, greater superficial petrosal nerve and labyrinthine segment of the facial nerve. If the classical landmarks are indiscernible during middle cranial fossa surgery, then the processus cochleariformis, with its intimate and constant relationships to inner-ear structures, is a safe and constant landmark.