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PubMed1996

Distance from the labyrinthine portion of the facial nerve to the basal turn of the cochlea. Temporal bone histopathologic study.

The middle cranial fossa approach to lesions of the geniculate ganglion and internal auditory canal preserves cochlear function and affords access to the lateral internal auditory canal. The labyrinthine portion of the facial nerve tends to course near the basal turn of the cochlea, just beneath the middle cranial fossa floor, and is usually dissected in this approach. To determine the distance from the labyrinthine portion of the facial nerve to the basal turn of the cochlea, measurements were obtained in the temporal bones of 24 subjects (48 ears) 9 to 76 years of age. These subjects had no history of facial nerve or ear disease, and had normal audiograms. The distances ranged from 0.06 to 0.80 mm, with 21 of 24 right ears (87.5%) showing distances less than the standard size of the smallest diamond drills (0.6 mm), and 18 of 24 (75%) less than 0.5 mm. Incidental note is made of the distance from the geniculate ganglion to the ampulla of the superior semicircular canal, which ranged from 2.06 to 4.88 mm in the 48 specimens. These measurements can serve as guidelines for the surgeon working in the middle cranial fossa.

Adolescent↗

PubMed2002

[Applied anatomy of abut structures of internal auditory meatus (IAM) through middle cranial fossa approach].

OBJECTIVE: To provide anatomical basis for operation of internal auditory meatus(IAM). Correlation structures with IAM were measured according to sign of hiatus of facial nerve. METHOD: These structures include spinous foramen, superficial geater petrosal nerve, superficial lesser petrosal nerve, hiatus of facial nerve were measured on 24 wet cranial bone (48 sides). RESULT: It is demonstrated that 8.3% geniculate ganglion and labyrinth segment of facial nerve Variation which distance from hiatus of facial nerve to geniculate ganglion is distinct. CONCLUSION: Our data will be very holpful for location of IAM during operation via middle cranial fossa approach.

Cranial Fossa, Middle↗

PubMed1991

Temporal bone pathology of acoustic neurinoma (unilateral and bilateral) in relation to the internal auditory canal surgery.

Temporal bone pathology of 3 cases with large unilateral acoustic neurinoma (AN) and 2 cases with large bilateral AN (neurofibromatosis 2; NF2) were studied. One case with unilateral AN was diagnosed as neurofibromatosis 1 (NF1). Unilateral AN had distinct borderlines at the fundus in 5 of 12 examination points between tumor tissues and nerve fibers, but only 1 of 12 was distinct around the porus acousticus. Bilateral AN showed no distinct borderlines at the fundus and around the porus acousticus. These findings suggest that clear separation of the VIIth or VIIIth nerve from large tumors is very difficult, especially in cases of bilateral AN. Geniculate ganglion cells of tumor origin on ears were fairly well preserved in 2 cases with unilateral AN and 1 case with bilateral AN. Well preserved geniculate ganglion cells could be dependent on blood supply not from the internal auditory artery.

Adolescent↗

PubMed2006

Discrete innervation of murine taste buds by peripheral taste neurons.

The peripheral taste system likely maintains a specific relationship between ganglion cells that signal a particular taste quality and taste bud cells responsive to that quality. We have explored a measure of the receptoneural relationship in the mouse. By injecting single fungiform taste buds with lipophilic retrograde neuroanatomical markers, the number of labeled geniculate ganglion cells innervating single buds on the tongue were identified. We found that three to five ganglion cells innervate a single bud. Injecting neighboring buds with different color markers showed that the buds are primarily innervated by separate populations of geniculate cells (i.e., multiply labeled ganglion cells are rare). In other words, each taste bud is innervated by a population of neurons that only connects with that bud. Palate bud injections revealed a similar, relatively exclusive receptoneural relationship. Injecting buds in different regions of the tongue did not reveal a topographic representation of buds in the geniculate ganglion, despite a stereotyped patterned arrangement of fungiform buds as rows and columns on the tongue. However, ganglion cells innervating the tongue and palate were differentially concentrated in lateral and rostral regions of the ganglion, respectively. The principal finding that small groups of ganglion cells send sensory fibers that converge selectively on a single bud is a new-found measure of specific matching between the two principal cellular elements of the mouse peripheral taste system. Repetition of the experiments in the hamster showed a more divergent innervation of buds in this species. The results indicate that whatever taste quality is signaled by a murine geniculate ganglion neuron, that signal reflects the activity of cells in a single taste bud.

Afferent Pathways↗

PubMed1985

Epidermoidomas of the cerebellopontine angle and temporal bone: CT and MR aspects.

Epidermoidomas were found in four locations within and adjacent to the temporal bone: cerebellopontine angle, petrous apex, facial geniculate ganglion region, and tympanic-mastoid cavity. Lesions in each of these locations presented different clinical and imaging characteristics. Cerebellopontine angle epidermoidomas were seen on computed tomography (CT) as low-attenuation masses in the posterior fossa. Petrous apex and geniculate ganglion region lesions destroyed and expanded the bone of their respective regions. Tympanic-mastoid cavity epidermoidomas were relatively nonspecific, soft-tissue masses. CT study of the brain and temporal bone was the single most informative imaging procedure in the preoperative evaluation of these lesions. Magnetic resonance images complemented CT scans for evaluation of the size and extent of the abnormality but were relatively nonspecific and did not allow preoperative differentiation of epidermoidomas from other temporal bone lesions.

Adolescent↗

PubMed2001

Dumbbell schwannomas of the internal auditory canal.

BACKGROUND AND PURPOSE: Benign tumors of the internal auditory canal (IAC) may leave the confines of the IAC fundus and extend into inner ear structures, forming a dumbbell-shaped lesion. It is important to differentiate dumbbell lesions, which include facial and vestibulocochlear schwannomas, from simple intracanalicular schwannomas, as surgical techniques and prognostic implications are affected. In this article, the imaging and clinical features of these dumbbell schwannomas are described. METHODS: A dumbbell lesion of the IAC is defined as a mass with two bulbous segments, one in the IAC fundus and the other in the membranous labyrinth of the inner ear or the geniculate ganglion of the facial nerve canal, spanned by an isthmus. Twenty-four patients with dumbbell lesions of the IAC had their clinical and imaging data retrospectively reviewed. Images were evaluated for contour of the mass and extension into the membranous labyrinth or geniculate ganglion. RESULTS: Ten of 24 lesions were facial nerve dumbbell lesions. Characteristic features included an enhancing "tail" along the labyrinthine segment of the facial nerve and enlargement of the facial nerve canal. Dumbbell schwannomas of the vestibulocochlear nerve (14/24) included transmodiolar (8/14), which extended into the cochlea, transmacular (2/14), which extended into the vestibule, and combined transmodiolar/transmacular (4/14) types. CONCLUSION: Simple intracanalicular schwannomas can be differentiated from transmodiolar, transmacular, and facial nerve schwannomas with postcontrast and high-resolution fast spin-echo T2-weighted MR imaging. Temporal bone CT is reserved for presurgical planning in the dumbbell facial nerve schwannoma group.

Adolescent↗

PubMed2003

High-resolution T1-weighted 3D real IR imaging of the temporal bone using triple-dose contrast material.

The small structures in the temporal bone are surrounded by bone and air. The objectives of this study were (a) to compare contrast-enhanced T1-weighted images acquired by fast spin-echo-based three-dimensional real inversion recovery (3D rIR) against those acquired by gradient echo-based 3D SPGR in the visualization of the enhancement of small structures in the temporal bone, and (b) to determine whether either 3D rIR or 3D SPGR is useful for visualizing enhancement of the cochlear lymph fluid. Seven healthy men (age range 27-46 years) volunteered to participate in this study. All MR imaging was performed using a dedicated bilateral quadrature surface phased-array coil for temporal bone imaging at 1.5 T (Visart EX, Toshiba, Tokyo, Japan). The 3D rIR images (TR/TE/TI: 1800 ms/10 ms/500 ms) and flow-compensated 3D SPGR images (TR/TE/FA: 23 ms/10 ms/25 degrees) were obtained with a reconstructed voxel size of 0.6 x 0.7 x 0.8 mm3. Images were acquired before and 1, 90, 180, and 270 min after the administration of triple-dose Gd-DTPA-BMA (0.3 mmol/kg). In post-contrast MR images, the degree of enhancement of the cochlear aqueduct, endolymphatic sac, subarcuate artery, geniculate ganglion of the facial nerve, and cochlear lymph fluid space was assessed by two radiologists. The degree of enhancement was scored as follows: 0 (no enhancement); 1 (slight enhancement); 2 (intermediate between 1 and 3); and 3 (enhancement similar to that of vessels). Enhancement scores for the endolymphatic sac, subarcuate artery, and geniculate ganglion were higher in 3D rIR than in 3D SPGR. Washout of enhancement in the endolymphatic sac appeared to be delayed compared with that in the subarcuate artery, suggesting that the enhancement in the endolymphatic sac may have been due in part to non-vascular tissue enhancement. Enhancement of the cochlear lymph space was not observed in any of the subjects in 3D rIR and 3D SPGR. The 3D rIR sequence may be more sensitive than the 3D SPGR sequence in visualizing the enhancement of small structures in the temporal bone; however, enhancement of the cochlear fluid space could not be visualized even with 3D rIR, triple-dose contrast, and dedicated coils at 1.5 T.

Adult↗

PubMed2005

Organization and microscopic anatomy of the adult human facial nerve: anatomical and histological basis for surgery.

BACKGROUND: Despite the progress in microsurgical repair of the facial nerve, the results remain unpredictable and the structural anatomy of the facial nerve poorly understood. The aim of this study was to show how the connective tissue and the nerve fibers are distributed in a serial cross-section of the facial nerve from its origin to its termination. METHODS: Sixty facial nerves from 30 embalmed adult human cadavers were dissected for micro-anatomic study. The facial nerves were serially sectioned every 2 mm from the apparent origin and were prepared for light microscopy study. The endoneural fascicular arrangement was observed, the number of myelinated fibers was counted, and connective tissue was explored. RESULTS: There was an absence of real fascicular organization of the facial nerve in the pontocerebellar cistern and in the internal acoustic meatus. The real fascicular organization with perineurium and epineurium appeared from the geniculate ganglion. The number of fascicles increased in a proximo-distal way, and their diameter diminished. In the extratemporal part, some nerves had a low number of fascicles (two to six), and others had a high number of fascicles (seven to 15). The number of fascicles changed along the course of the facial nerve, especially in the extratemporal part. CONCLUSIONS: The truly fascicular structure appeared after the geniculate ganglion, and the rate of connective tissue progressed in a proximo-distal way. The high numbers of fascicles and the great structural variability of each facial nerve segment constitute a difficulty in nerve repair.

Adult↗

PubMedDate not supplied

Transmastoid decompression of the facial nerve in temporal bone fracture.

Among 41 cases of facial palsy caused by closed heart injury, temporal bone fractures were surgically confirmed in 36 cases, of which there were two mixed fractures and 34 longitudinal fractures. The fracture involved the geniculate ganglion area in 20 cases (55%). In 15 cases, decompression of the facial nerve was carried out using the transmastoid supralabyrinthine approach with disarticulation of the incus; in only five cases was the middle fossa approach used. The technique avoids the craniotomy for the middle fossa approach and is a reliable method of treatment in the majority of patients with facial palsy caused by temporal bone fracture involving the geniculate ganglion area.

Facial Nerve↗

PubMed1993

[Facial nerve paralysis induced by herpes simplex virus infection in mice].

The etiology of Bell's palsy remains unknown but clinical serological investigations have suggested herpes simplex virus (HSV) induced facial neuritis to be a potential cause. In order to verify the viral etiology of Bell's palsy it must be proved by animal experimentation. The author first succeeded in producing a transient facial paralysis of mice, with a herpes simplex viral neuritis simulating human Bell's palsy. Type 1 HSV (strain KOS, 4.5 X 10(6) pfu/ml) was inoculated into the posterior aspect of the auricle. Fifty-nine out of 104 mice (56.7%) developed facial paralysis, on the experimental side, 6 to 9 days after the inoculation. The facial paralysis continued for 3 to 7 days and resolved spontaneously. In 36.8% of the animals with facial palsy, HSV antigens were identified mainly in the geniculate ganglion cells, satellite cells, Schwann cells and nerve fibers of the involved side using immunohistochemical methods. No HSV antigen was demonstrated in the facial nerve of the contralateral side in animals with facial paralysis, bilateral facial nerves in animals without facial palsy or in control animals. Histopathologically, the involved nerve showed findings of viral neuritis such as round cell infiltration and vacuolar degeneration of nerve fibers. Inflammatory changes were noted in and around the geniculate ganglion but were more pronounced in nerve fibers proximal to the ganglion. These findings persisted for as long as a month after normal facial function had been restored.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1998

Delayed facial palsy following uneventful middle ear surgery: a herpes simplex virus type 1 reactivation?

In rare cases, a facial palsy appears a few days after uneventful middle ear surgery. The reason for this delayed palsy is unclear. One hypothesis is that it results from a reactivation of herpes simplex virus type 1 (HSV-1) in the geniculate ganglion of the facial nerve. From 1987 to 1996, in the course of over 1,800 middle ear operations, we observed 7 ipsilateral delayed facial palsies and investigated 5 of them using immunologic and virologic methods, including the polymerase chain reaction (PCR). We could detect HSV-1 genome with the nested primer PCR in the tongue swabs of 4 of the 5 examined patients with delayed facial palsy. The immunologic changes in these palsies are also compatible with a reactivation of HSV-1. We conclude that minimal stimulation of the facial nerve during middle ear surgery could result in a reactivation of HSV-1 in the geniculate ganglion, which may in turn lead to a facial palsy.

Adult↗

PubMed2000

Edematous swelling of the facial nerve in Bell's palsy.

Surgical decompression of the intratemporal facial nerve from the geniculate ganglion to the stylomastoid foramen was carried out in 91 patients with Bell's palsy. All of the patients had denervation exceeding 95%, and a suprastapedial lesion. Edematous swelling of the nerve was assessed using the following three grades: + +, nerve swells beyond the bony facial canal; +, nerve swells beyond the nerve sheath, but within the bony canal, and -, no notable swelling observed. Varying degrees of swelling of the nerve were noted in all of the patients from onset to the end of the ninth week. The incidence of + + swelling was highest within 3 weeks of onset and then declined. + + swelling was most often noted in the vicinity of the geniculate ganglion, and was thought to be a manifestation of inflammation due to herpes simplex virus infection. There was a clear time dependency of the swelling in the horizontal and pyramidal segments, but not in the mastoid segment. After the ninth week, the incidence of swelling decreased sharply and no swelling of the nerve was observed in about one-third of the patients. Considering the etiology and the analysis of edematous swelling, we propose that the course of Bell's palsy be differentiated into an acute phase (the first 3 weeks after onset), a subacute phase (from the fourth to ninth weeks) and a chronic phase (after the tenth week).

Adolescent↗

PubMed1979

Alkaline phosphatase activity in the ganglion cells in and near the temporal bone.

The distribution pattern of alkaline phosphatase was studied in the ganglion cells in and near the temporal bone of some mammals. No or extremely weak activity of alkaline phosphatase was observed in or near the spiral and vestibular ganglion cells of the bat, rat, cat, and monkey. However, intense to moderate enzyme activity was noted exclusively in the peripheral areas of the spiral and vestibular ganglion cells of the guinea pig. The enzyme activity was also demonstrated in the nerve fibers at some distance from both axonal and dendritic processes of the spiral and vestibular ganglion cells of the guinea pig. Trigeminal and geniculate ganglion cells of all mammals examined showed intense to moderate enzyme activity in their capsular cells. There is a marked difference in the phosphate metabolism in the capsular tissues of the ganglion cells in or near the temporal bone of various mammals.

Alkaline Phosphatase↗

PubMed1999

Surgical management of Bell's palsy.

OBJECTIVES: Incomplete return of facial motor function and synkinesis continue to be long-term sequelae in some patients with Bell's palsy. The aim of this report is to describe a prospective study in which a well-defined surgical decompression of the facial nerve was performed in a population of patients with Bell's palsy who exhibit the electrophysiologic features associated with poor outcomes. In addition, management issues related to Bell's palsy including herpes simplex virus typel etiology, the natural history, electrodiagnostic testing, and efficacy of surgical strategies are reviewed. STUDY DESIGN AND METHODS: A multicenter prospective clinical trial was designed utilizing electroneurography (ENOG) and voluntary electromyography (EMG) to identify patients with Bell's palsy who would most likely develop poor return of facial function, as suggested by Fisch and Esslen. Patients who displayed electrodiagnostic features of poor outcome, >90% degeneration on ENOG testing and no voluntary motor unit EMG potentials within 14 days of onset of total paralysis, were offered a surgical decompression of the facial nerve through a middle cranial fossa surgical exposure, including the tympanic segment, geniculate ganglion, labyrinthine segment, and meatal foramen. Control subjects were those who displayed similar electrodiagnostic features and time course. RESULTS: Subjects who did not reach 90% degeneration on ENOG within 14 days of paralysis all returned to House-Brackmann grade I (n = 48) or II (n = 6) at 7 months after onset of the paralysis. Control subjects self-selecting not to undergo surgical decompression when >90% degeneration on ENOG and no motor unit potentials on EMG were identified had a 58% chance of developing a poor outcome at 7 months after onset of paralysis (House-Brackmann grade III or IV [n = 19]). A group with similar ENOG and EMG findings undergoing middle fossa facial nerve decompression exhibited House-Brackmann grade I (n = 14) or II (n = 17) in 91% of the cases. An exact permutation test confirmed that the surgical group had a significantly higher proportion of patients with a good outcome (House-Brackmann grade I or II) (P = .0002). CONCLUSION: Electroneurography in combination with voluntary EMG successfully identified patients who will most likely return to normal from those who had a greater chance of long-term sequelae from Bell's palsy. Surgical decompression medial to the geniculate ganglion significantly improves the chances of normal or near-normal return of facial function in the group that has a high probability of a poor result. Surgical decompression must be performed within 2 weeks of onset of total paralysis for it to be effective.

Adult↗

PubMed1992

The bony crescent sign--a new sign of facial nerve schwannoma.

Schwannomas of the facial nerve are rare slowly growing lesions that have a predilection for the geniculate ganglion. Radiological evaluation is important in their diagnosis and in the assessment of their extent. In our series of 4 cases the facial nerve schwannoma was seen on high resolution CT as a soft tissue mass bounded anteriorly by a thin rim of bone. This bony crescent sign is a previously undescribed sign of facial nerve schwannoma which appears on the basis of this small series to be strongly indicative of the presence of this tumour. Schwannomas are relatively uncommon intracranial tumours. They most commonly involve the acoustic nerve followed in frequency by the trigeminal nerve. Other cranial nerves are rarely involved. Facial nerve schwannomas occurring within the petrous temporal bone are very rare. Their diagnosis may be missed prospectively even when appropriate CT scans are performed. Even in retrospect the site of abnormality may be difficult to identify, especially if there is an associated middle ear mass such as a cholesteatoma. Lesions occurring in the petrous area are all rare. The differential diagnosis includes cholesterol granuloma, epidermoid, carotid aneurysm and, very rarely, primary and secondary bone tumours. We describe a new sign associated with facial nerve schwannoma on CT, that of a bony crescent. Recognition of this sign makes those tumours arising in the region of the geniculate ganglion easy to diagnose prospectively.

Adolescent↗

PubMed2000

Selective indications for the management of extensive anterior epitympanic cholesteatoma via combined transmastoid/middle fossa approach.

OBJECTIVES/HYPOTHESIS: Cholesteatoma that is present in the anterior epitympanic space may extend medially along the supralabyrinthine route to the geniculate ganglion, labyrinth, and cochlea and medially toward Kawase's triangle and the anterior petrous apex. Superiorly it may erode into the middle fossa. Contemporary microsurgical techniques allow for optimal management of these lesions with minimal morbidity, provided that the irregular and complex osteology of the petrous base is understood. The objective of the study was to review the relevant regional anatomy, pathobiology, and current algorithm used in treatment of this select patient population using a combined transmastoid/middle fossa (TM/MF) approach. METHODS: A retrospective review was performed of all clinical and radiographic data from patients undergoing combined TM/MF management of extensive anterior epitympanic cholesteatoma between July 1984 and June 1998. Data from physical examinations, preoperative imaging studies, and operative findings and other relevant data were tabulated and analyzed for patients undergoing TM/MF management of cholesteatoma. RESULTS: Of 488 patients with cholesteatoma treated by the otological service between 1984 and 1998, 11 patients underwent TM/MF exposure and removal of anterior epitympanic cholesteatoma. Total cholesteatoma removal was accomplished in six patients. In three patients, because of facial nerve involvement, labyrinthine fistulae, or internal carotid artery involvement, open-cavity surgery was performed. In two patients, residual or recurrent cholesteatoma was exteriorized at "second-look" procedures. In this small cohort of patients the majority had extension to the arcuate eminence, geniculate ganglion, or Kawase's triangle or had "blue-lining" of the cochlea or labyrinth. To a lesser degree, the middle ear and mastoid contents were involved. Further facial nerve dysfunction or sensorineural hearing loss was not noted after surgery. CONCLUSIONS: Selective TM/MF removal of cholesteatoma provides an optimal route for removing complex cholesteatoma in patients with intact sensorineural function and medial cholesteatoma extension.

Adolescent↗

PubMed1975

Quantitative studies on the motor root of the mouse facial nerve. An electron-microscopic study.

Fiber count analysis was performed with the electron microscope on the motor root of the facial nerve in six mice. On an average, 3,433 (84.9%) of the total nerve fibers (4,046) were myelinated and 592 (14.6%) unmyelinated. The motor root consisted mostly of large myelinated fibers (large fiber group), but a part of the root consisted of small myelinated and unmyelinated fibers (small fiber group). The nerve fibers of the small fiber group appear to correspond with those of the intermediate nerve, and to pass through the motor root and enter the intermediate nerve near the geniculate ganglion.

Animals↗

PubMed1976

Geniculate neuralgia: diagnosis and surgical management.

Pain in the ear is a common complaint for which patients consult their otolaryngologist. A rare cause is geniculate neuralgia, which has also been called tic douloureux of the nervus intermedius. In its most typical form, it is characterized by severe paroxysmal neuralgic pain centered directly in the ear. The pain may also be of gradual onset and of a dull, persistent nature, with occasional sharp, stabbing pain. The diagnostic features and two new surgical techniques for its treatment are described. Afferent sensory facial nerve fibers are shown to pass not only through the nervus intermedius, but also through the main motor trunk of the facial nerve. Excision of the nervus intermedius and/or of the geniculate ganglion by the middle cranial fossa approach without the production of facial paralysis, in any of 15 cases with geniculate neuralgia is reported. Use of these new techniques, sometimes in combination with selective section of the Vth cranial nerve, has been successful in relieving the pain of geniculate neuralgia.

Adult↗