Ossification patterns of the tympanic facial canal in the human fetus and neonate

Dehiscences in the bony facial canal are comparatively common in the human adult. The highest incidence occurs in the tympanic segment of the facial nerve near the region of the oval window. Thirty-three fetal temporal bones, ranging from 16 to 40 weeks' gestation, and four from 1, 2, 4 and 12 weeks' postpartum neonates, were studied to evaluate the normal patterns of ossification of the fallopian canal of the tympanic facial nerve segment in the human. The tympanic facial nerve segment elongates threefold during this period (from 1 mm to 3 mm). The ossification starts at 21 weeks' gestation anteriorly from apical otic ossification centers and at 26 weeks from canalicular ossification centers near the stapedius muscle. The ossification proceeds in an anterior-to-posterior direction as two periosteal shelves of bone surround the facial nerve. The superior periosteal bony ledge contributes 75% of the circumference of the fallopian canal. The anterior ossification center forms over 83% of the fallopian canal length. The two centers fuse post partum near the region of the oval window. The anatomic location of the facial nerve, nerve branching, and neural vasculature precede ossification. In 80% of the paired temporal bones, this ossification pattern appears to be symmetrical. The patterns and incidence of bony dehiscences within the tympanic fallopian canal segment can be explained by these observations. This study demonstrates that fallopian canal dehiscences are not congenital anomalies, but variations of normal developmental anatomic processes.     

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

Objective To 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. Methods Eighteen 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 gradeⅤ 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. Results Pronounced 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 gradeⅠin 11 cases, Ⅱ in 5 cases and Ⅲ in 2 cases. Overall hearing recovery was 33 dB. Conclusion The 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.     

Distribution of psammoma bodies in the internal auditory canal and its extended areas in the human temporal bone.

The internal auditory canal (IAC) and its extended areas of 27 normal human temporal bone specimens were investigated histologically for the distribution of psammoma bodies. A total of 145 +/- 25 (mean +/- SE) psammoma bodies were counted in series of every tenth 30-microm-thick section. Psammoma bodies were observed in the IAC and around the labyrinthine portion of the facial nerve (FN), the geniculate ganglion of the FN, and the posterior ampullary nerve in the singular canal. The number of psammoma bodies increases with age. We believe that psammoma bodies are a normal finding of aging in the IAC. The compression of the FN by psammoma bodies in the labyrinthine portion of the facial canal and the distribution of numerous psammoma bodies surrounding the posterior ampullary nerve in the narrow singular canal raise the questions of the involvement of psammoma bodies in the FN and in vestibular dysfunction and the presence of psammoma bodies in the subarachnoid space.     

Histopathology of the facial nerve after longitudinal temporal bone fracture

The temporal bone histopathology in a patient who suffered repeated head trauma and a longitudinal temporal bone fracture shows unusual features associated with the facial nerve. In the distal meatal segment, a type of traumatic neuroma was found with disorganized nerve bundles and distinct areas of Schwann's cell proliferation but lacking fibrosis. Periosteal new bone formation in the labyrinthine segment narrows the fallopian canal and protrudes into the nerve, which completely fills the canal. The tympanic and mastoid segments of the nerve show severe degeneration of nerve fibers and an increase in connective tissue between fascicles. An attempted facial nerve decompression did not reach the area of primary pathology in the labyrinthine and meatal segments of the nerve, which could have been exposed by the transtemporal supralabyrinthine approach.     

中耳手术中的面神经定位

目的结合颞骨解剖和面神经手术，明确适用于手术的面神经解剖标志。方法44具颞骨标本面神经解剖，106例周围性面神经麻痹的面神经减压手术。根据面神经周围的固定解剖标志，确定面神经位置。结果①面神经垂直段标志：水平半规管后中1／3交界处垂直线提示面神经后缘；砧骨短角上缘弧度延长线为面神经垂直段前缘；面神经与水平半规管基本在同一深度；②面神经水平段标志：位于砧骨短突之下；在水平半规管隆突前缘向前上呈30。行走；在匙突后方，面神经与匙突平行形成中上鼓室内侧面交界缘；经过匙突面神经向前上行走到膝状神经节；③膝状神经节定位：从镫骨头到匙突等距离延长线为膝状神经节位置；④鼓索神经定位：鼓索从左侧鼓沟的3点或右侧鼓沟的9点出骨管，沿鼓沟向前行走于砧骨长突外侧和锤骨颈内侧；鼓索神经从面神经发出处距离茎乳孔5—8mm；鼓索位于鼓膜紧张部与松弛部交界处。所有手术所见面神经走向符合解剖所见。结论中耳乳突的固定标志是面神经定位的参照物，其中水平半规管的位置最恒定，根据参照物确定面神经位置提高了手术的安全性。     

Pleomorphic adenoma involving the stylomastoid foramen

A rare case of an intratemporal pleomorphic adenoma is presented and the management of such a tumour is discussed. Some anatomical aspects of the facial nerve, pertinent to the pathophysiology of facial paralysis are outlined. This case demonstrates that tumour extension into the temporal bone can be resected successfully at initial surgery with excellent facial nerve functional outcome. We advocate exploration of the fallopian canal to be carried out at primary surgery and be performed by a surgeon familiar with the surgical anatomy of the intratemporal segment of the facial nerve. This approach will reduce the risk of facial nerve injury and palsy both at surgery and subsequently.     

Fallopian canal dehiscences: a survey of clinical and anatomical findings

This survey investigates fallopian canal dehiscences in order to assess the risk of encountering an unprotected facial nerve during routine ear surgery. In a prospective non-randomized study, the intraoperative appearance of the facial canal in 357 routine ear operations was compared with 300 temporal bone specimens from 150 autopsies. Intraoperatively, a dehiscence was detected in 6.4% (23/357) of the operations, most frequently at the oval niche region (16/23 cases). The incidence increased with the number of operations (P<0.0002). Cholesteatoma surgery had the highest relative risk (RR 4.6) of exposing an unprotected facial nerve. Postoperatively, no persistent facial paralysis was observed. In four of five cases with a transient facial palsy due to local anesthetics, a bony dehiscence could be found. The anatomical study revealed fallopian canal dehiscences in 29.3% (44/150) of the autopsies. One-third (15/44) of the individuals affected displayed bilateral findings, thus resulting in 19.7% (59/300) of temporal bones affected. A total of 17/59 bones showed microdehiscences, and most (55/59) were located at the oval niche. The actual prevalence of fallopian canal dehiscences is significantly higher than intraoperative findings suggest. The oval niche is the most affected region. High-resolution computed tomography is of diagnostic value only in selected cases. Facial paralysis following local anesthesia is the most significant clinical sign. Vigilance in acute facial palsy after local anesthetics and in cholesteatoma surgery and adequate intraoperative exposure help to prevent iatrogenic injury of the uncovered nerve. In unclear cases, nerve monitoring can facilitate a safe outcome.     

Metastatic carcinoma mimicking a facial nerve schwannoma: the role of computerized tomography in diagnosis

Secondary deposits in the temporal bone are uncommon but well recognized. Such tumours may involve the facial nerve by direct extension of the destructive process into the fallopian canal. We present a rare case of metastasis from a breast carcinoma in the facial nerve itself, involving the nerve in the internal acoustic meatus with extension into the labyrinthine segment, the first genu and into the middle-ear segment. The rest of the temporal bone was not involved. The lesion resembled a facial schwannoma on a routine magnetic resonance (MR) image. The diagnosis was confirmed after a post-operative computed tomography (CT) scan showed another separate secondary deposit in the basisphenoid. Histology was consistent with secondary tumour from a breast carcinoma. The case highlights the importance of keeping a high degree of suspicion for metastatic tumours in patients with a previous history of malignancy and the usefulness of CT scan in the evaluation of such cases.     

Facial nerve paralysis secondary to mandibular fracture

When facial nerve paralysis complicates a mandibular fracture, it may be difficult to locate the point of injury, since the nerve may be injured in the fallopian canal by a secondary temporal bone fracture or in soft tissue by mandibular fragments. Following a review of eight previously reported cases, this paper presents two additional cases, one with bilateral, complete paralyses and the other with a unilateral paresis. In the first, the condyles were driven posteriorly, resulting in bilateral temporal bone fractures, a unilateral external canal stenosis, and a unilateral sensorineural hearing impairment. Good functional return followed decompression of the intratemporal facial nerves. In the second patient, facial function returned spontaneously. When the temporal bone is fractured, therapy follows guidelines for facial paralysis associated with basilar skull fractures from other causes. If soft tissue injury is suspected, the decision must be made whether to explore the nerve or wait for spontaneous recovery.     

儿童颞骨骨折临床特点和治疗策略

目的 探讨儿童颞骨骨折的临床特点及治疗策略.方法 回顾性分析2014年7月～2021年7月首都医科大学附属北京儿童医院确诊的477例18岁以下颞骨骨折患儿的临床资料,包括患儿性别、年龄、受伤原因、影像学、面神经及听力学评估、并发症、治疗及预后.结果 477例颞骨骨折患儿中男358例、女119例,男女比例为3∶1,年龄范...     

The radiographic prevalence of geniculate ganglion dehiscence in normal and congenitally thin temporal bones.

OBJECTIVE: To determine the prevalence of a dehiscent geniculate ganglion on routine temporal bone computed tomography (CT). STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Two hundred seventy-eight consecutive temporal bone CT examinations for a total of 556 sides were reviewed. One hundred ninety-one sides were excluded. Reasons for exclusion included reconstructed coronal views, no coronal views, or a pathologic process, which involved the geniculate ganglion. Six examinations were from patients with clinical superior canal dehiscence confirmed by surgical repair or positive vestibular evoked myogenic potentials. Twenty-four scans were from patients with radiographic superior canal dehiscence confirmed by two independent readings. MAIN OUTCOME MEASURES: The incidence of geniculate ganglion dehiscence in patients with and without radiographic or clinical superior canal dehiscence. Dehiscent geniculate ganglion was defined as at least two consecutive cuts on a coronal CT showing no bone overlying the geniculate ganglion. RESULTS: The overall incidence of a dehiscent geniculate ganglion was 14.5% in the 365 sides reviewed. The incidence of a dehiscent geniculate ganglion is increased in patients with radiographic and clinical superior canal dehiscence as compared with normal patients and was significantly different by chi analysis (38.1 versus 11.4%). CONCLUSION: The presence of radiographic geniculate ganglion dehiscence is common. This finding has particular importance when the middle cranial fossa or subtemporal approach is used, as the facial nerve is more at risk especially when used to address superior canal dehiscence.     

Reliability of temporal bone high-resolution CT in patients with facial paralysis in temporal bone fracture

Objective

This study aimed to investigate the reliability of temporal bone high-resolution CT (HRCT) in patients with traumatic facial paralysis.

Transcochlear repair of persistent cerebrospinal fluid leaks.

OBJECTIVE: The purpose of this study is to demonstrate the utility of a modified transcochlear obliteration of the petrous apex in repair of persistent cerebrospinal fluid (CSF) leaks. A review of temporal bone computed tomography (CT) scans and histological preparations for potential air cells leading to such leaks is also presented. STUDY DESIGN: Retrospective case review in an academic tertiary referral center. METHODS: Patients for inclusion in this study had previously undergone either a suboccipital or translabyrinthine removal of an intracranial tumor with subsequent transmastoid and middle ear obliteration of air cell tracts to stop a CSF leak. Ninety CT scans and 178 temporal bones were reviewed and assessed for peritubal and petrous apex pneumatization. RESULTS: Four patients had initial obliteration of the orifice of the eustachian tube and middle ear that failed to prevent leakage of CSF. The leak was ultimately controlled by a transcochlear petrous apicectomy. From The Ohio State University temporal bone collection, 178 specimens were available for examination. Peritubal pneumatization was found in 42% of the bones examined. The CT scans showed unilateral petrous apex pneumatization in 30% of the specimens and bilateral pneumatization in 11%. CONCLUSIONS: Continuity of air cell tracts from the petrous apex surrounding the internal auditory canal to the medial eustachian tube can provide a path for CSF rhinorrhea that is difficult to stop by conventional means. A modified transcochlear approach successfully terminated persistent leaks in four such patients.     

Non-communicating arachnoid cyst of the temporal bone presenting as facial nerve paralysis in an infant.

Non-communicating arachnoid cyst of the lateral temporal bone is a rare condition. We present a case of a non-communicating arachnoid cyst of the temporal bone in an infant who presented with a lower motor neuron facial nerve paralysis. The patient was treated by surgical excision of the cyst.     

Facial nerve paralysis caused by middle ear cholesteatoma and effects of surgical intervention

CONCLUSIONS: The clinical and surgical findings of this study indicated advanced cholesteatoma in many patients with facial paralysis. The outcome of facial paralysis was good. Poor outcomes were observed in cases with petrosal cholesteatoma and in those who underwent surgery > or = 2 months after the onset of paralysis. OBJECTIVE: To investigate clinical features of cholesteatoma associated with facial paralysis. MATERIAL AND METHODS: Sixteen patients with facial paralysis due to middle ear cholesteatoma were reviewed. After removal of the cholesteatoma lesion, a limited area of the fallopian canal, that in which facial nerve edema or redness was evident, was opened. Incision of the epineural sheath for nerve decompression was not performed. RESULTS: Initial paralysis was incomplete in 11 patients (69%). The onset of paralysis was sudden in 12 patients (75%). Labyrinthine fistulae (n = 9; 56%) and bone destruction in the cranial fossa (n = 10; 63%) were frequently observed. Six patients (38%) were totally deaf due to labyrinthitis. The outcome of facial paralysis was good in 13 patients (81%). Patients who underwent surgery > or = 2 months after the onset of paralysis frequently had a poor outcome. Paralysis was not improved in two cases with petrosal cholesteatoma.     

Arachnoid granulations of the posterior temporal bone wall: report of two cases

Arachnoid granulations play a role in CSF drainage. They are primarily located adjacent to cerebral venous sinuses. They may arise on a bony surface causing progressive bony erosion. We report two cases of arachnoid granulations eroding the posterior wall of the temporal bone. The aim of this paper was to illustrate the clinical presentation, and the imaging findings of arachnoid granulation of the posterior wall of the temporal bone. They remain asymptomatic in most cases, but they might cause a communication between the subarachnoid space and mastoid air cells, increasing the risk of bacterial meningitis, subdural empyema, and other intracranial infections. Differential diagnoses are also described, including endolymphatic sac tumours.     

Total-length invasion of the facial nerve by parotid carcinoma ex pleomorphic adenoma

A case of parotid carcinoma extending along the facial nerve up to the internal auditory canal is presented. Total parotid resection with neck dissection was performed, as well as resection of the ear canal, eardrum, ossicles, and transmastoid and translabyrinthine facial nerve, and obliteration using the fascia lata and fatty tissue. This was followed by adjuvant radiotherapy. The facial nerve showed continuous swelling along its length with lump formation at the site of the geniculate ganglion and the internal acoustic canal. Pathological examination revealed the salivary duct carcinoma subtype of carcinoma ex pleomorphic adenoma. Within the facial nerve, the epineurium, perineurium and endoneurium were affected throughout its length. Preoperative MRI with a contrast medium revealed the site of lump formation on the facial nerve, though it did not reveal the consecutive spread of the tumor along the nerve trunk. CT of the temporal bone is strongly recommended for detection of swelling of the temporal bone segment of the nerve trunk, which could provide confirming evidence of invasion by a parotid carcinoma.     

Chondromyxoid fibroma of the mastoid facial nerve canal mimicking a facial nerve schwannoma

Chondromyxoid fibroma of the skull base is a rare entity. Involvement of the temporal bone is particularly rare. We present an unusual case of progressive facial nerve paralysis with imaging and clinical findings most suggestive of a facial nerve schwannoma. The lesion was tubular in appearance, expanded the mastoid facial nerve canal, protruded out of the stylomastoid foramen, and enhanced homogeneously. The only unusual imaging feature was minor calcification within the tumor. Surgery revealed an irregular, cystic lesion. Pathology diagnosed a chondromyxoid fibroma involving the mastoid portion of the facial nerve canal, destroying the facial nerve. Laryngoscope, 2009     

Management of intratemporal vascular tumors.

Vascular tumors (vascular malformations and hemangiomas) of the temporal bone are uncommon, and guidelines for their management have not been published. In an effort to develop an approach to their management, the present study examined the pathological, clinical, and surgical experience with ten of these lesions treated at the Otologic Medical Group, Inc., and St. Vincent Medical Center in Los Angeles from 1960 to 1980. Intratemporal vascular tumors occurred most frequently at two sites, the internal auditory canal and the geniculate ganglion. Histological features and clinical behavior did not correlate. Both vascular malformations and hemangiomata invaded the facial nerve. Surgical excision in these cases required severence and repair of the involved facial nerve. Complete surgical excision is the treatment of choice of vascular lesions of the temporal bone.     

Canal wall window mastoidectomy for extensive labyrinthine cholesteatoma: total dissection and hearing preservation

This case report highlights outcomes of a 6-year-old patient who preserved functional hearing after complete dissection of an extensive labyrinthine cholesteatoma causing two semicircular canals fistulas with endolymph leak, tympanic and labyrinthine fallopian canal erosion of the facial nerve and internal auditory canal invasion with cerebrospinal fluid leak. The patient preserved 40 dB average of bone conduction threshold and 92% of speech discrimination score at 26 months postoperatively. This article reveals that canal wall window mastoidectomy might be an option even in cases of extensive cholesteatomatous labyrinthine fistula therefore avoiding hearing loss and long life cleaning of a canal wall down mastoid cavity.