Radiographic differential diagnosis of petrous apex lesions.

As a consequence of improved diagnostic imaging modalities, otologists have encountered a steadily increasing number of petrous apex lesions in recent years. Contemporary imaging techniques not only provide precise anatomic localization of the lesion, but also are able to suggest specific tissue diagnoses in the majority of cases. Computed tomography (CT), by virtue of its sensitivity and low false-positive rate, is the screening examination of choice in a patient suspected of having a petrous apex lesion. Once a lesion is identified, it is often necessary to obtain a combination of CT and magnetic resonance imaging (MRI). Computed tomography is important in the detection of osseous erosion as well as in the evaluation of the extent of pneumatization and marrow formation. It also provides important details about potential surgical routes to this relatively inaccessible region. Magnetic resonance imaging provides information about the composition of the lesion that cannot be readily discerned on CT scans. In the great majority of cases, it is capable of differentiating between petrous apicitis, cholesterol granuloma, osteomyelitis, cholesteatoma, and neoplasms such as schwannoma, meningioma, chondroma, and chordoma. In the interpretation of MRI scans, a familiarity with the typical appearance of the lesions that affect the petrous apex on T1-weighted, T2-weighted, and gadolinium-enhanced images is essential. A combination of MRI and CT scanning is also necessary to evaluate normal anatomic variations, such as giant air cells and asymmetric bone marrow, which may at times, on MRI alone, simulate pathologic conditions.     

Incidental petrous apex findings on magnetic resonance imaging

We performed a retrospective chart review to categorize a group of petrous apex findings that were noted incidentally on magnetic resonance imaging (MRI) in 88 patients. These patients were among those who had been seen at a tertiary care center between July 1988 and July 1998. These incidental findings, which were unrelated to the presenting clinical manifestations, included asymmetric fatty bone marrow (n = 41), inflammation (19), cholesterol granulomas (14), cholesteatomas (9), and neoplasms (5). Followup imaging and clinical surveillance of these patients has not demonstrated any significant change in the incidentally detected lesions. In all cases, the incidental MRI findings represented benign pathology.     

Primary cholesteatoma of the middle ear and petrosal bone

Petrosal cholesteatomas are rare lesions, which may be primary or acquired in nature. We report a case of primary cholesteatoma in petrous bone occurring in 51-year old woman who presented with a unilateral facial nerve palsy and conductive hearing loss, despite normal tympanic membrane appearance. Early diagnosis was facilitated by computed tomography scanning and magnetic resonance imaging. Complete cholesteatoma removal was accomplished using a transtemporal supralabyrinthine approach, which allowed hearing preservation. Facial nerve function is the main complication of these lesion. We suggest that use of CT scanning and MRI in unilateral conductive hearing loss may allow the earlier detection of the most cases of petrosal cholesteatomas.     

Intracranial Extension of Acquired Aural Cholesteatoma

Objective Cholesteatoma of the petrous bone extending into the intracranial region is an unusual occurrence. Most cases have been attributed to secondary extension of a primary epidermal blastomatous malformation of the temporal bone into the middle or posterior fossae. Within the past two and a half decades, intracranial extension of acquired aural cholesteatoma has been recognized as a likely alternative to this mechanism. Recent literature has rejoined this observation by considering both primary and secondary cholesteatoma of the petrous bone as a single group, petrosal cholesteatoma. The present study is presented to analyze the clinical presentation, imaging findings, and surgical treatment of six patients with acquired aural cholesteatoma extending into the intracranial region. Findings in this study are compared with the extant literature on congenital and acquired cholesteatoma of the petrous bone. This study proposes that petrosal cholesteatoma is a valid anatomical construct; however, the pathogenesis of petrosal cholesteatoma is still important in understanding the clinical presentation and management of cholesteatoma that extends beyond the usual confines of the middle ear and mastoid. Study Design Retrospective case review conducted at a tertiary referral center. Methods From 1985 to 1999, 477 patients were surgically treated for acquired aural cholesteatoma. Patients with intracranial extension of cholesteatoma were studied. Clinical presentation, imaging studies, operative findings, surgical treatment, and postoperative results were evaluated. Results Six cases in a series of 477 patients with acquired aural cholesteatoma had intracranial extension of disease. In this series, the most frequent pathway for intracranial extension was supralabyrinthine through the supratubal recess into the middle cranial fossa. A less frequent pathway was via the retrofacial air cells into the posterior cranial fossa. Surgical access for removal of intracranial cholesteatoma was accomplished through several approaches including translabyrinthine, transcochlear, retrolabyrinthine, and middle cranial fossa. In two patients who had reoperation for possible residual disease, one was free of residual disease and one was found to have residual cholesteatoma in the region of the horizontal facial nerve. Conclusion Acquired aural cholesteatoma can extend into either the middle or posterior cranial fossae. In this study, cholesteatoma extended into the middle fossa through the supratubal recess along the labyrinthine facial nerve and into or above the internal auditory canal. A less frequent path is through the retrofacial air cells into the posterior fossa. Intracranial acquired cholesteatoma is generally small and presents with complaints related to underlying otitis media rather than the neurological deficits that are often associated with primary petrous bone cholesteatoma. While computed tomography and magnetic resonance imaging are both required to differentiate congenital petrous cholesteatoma from other lesions of the petrous bone, computed tomography of the temporal bone is usually sufficient to diagnosis and define intracranial extension of acquired aural cholesteatoma. These lesions can be completely excised rather than exteriorized.     

Infantile congenital petrosal cholesteatoma: a case report and literature review

Congenital cholesteatoma of the middle ear is frequently seen in younger children including infant. By contrast, that of the petrous bone is rarely seen in younger children. We report an exceptional case occurring in 23-month-old infant who presented with unilateral facial nerve paralysis at about 18-month-old. Computed tomography and magnetic resonance imaging revealed congenital cholesteatoma measuring approximately 2 cm in the area of the right geniculate ganglion. The mass was completely eradicated via the middle fossa approach, which allowed for preservation of hearing. The facial nerve maintained intact during surgery and paralysis showed partial recovery after the operation. To our knowledge, the present case seems to be the youngest case of congenital petrosal cholesteatoma reported, and also demonstrates congenital petrosal cholesteatoma could exhibit facial nerve paralysis in early childhood.     

Imaging Destructive Lesions of the Petrous Apex

Cholesterol granuloma and cholesteatoma are the two most common destructive lesions of the petrous apex. Arachnoid cyst is less common. These three expansile lesions are often indistinguishable on clinical grounds. Cholesterol granulomas can be treated effectively through internal drainage into the mastoid cavity or middle ear. Cholesteatomas, however, are managed by more aggressive and complicated removal, which often mandates the sacrifice of hearing. Symptomatic arachnoid cysts are amenable to simple surgical drainage. Therefore, accurate preoperative recognition on computed tomography (CT) and magnetic resonance imaging (MRI) is important in planning proper treatment. Thirteen cases of destructive lesions of the petrous apex are analyzed. The authors' experience illustrates that the “typical” CT and MRI radiographic features are diagnostic in some cases, but not in all. In this study the pathologic findings have been correlated with the radiologic features on both MRI and CT.     

Middle ear carcinoma originating from a primary acquired cholesteatoma: a case report.

OBJECTIVES: To describe middle ear carcinoma originating from the matrix of primary acquired cholesteatoma in a 43-year-old man and to discuss the relationship between middle ear carcinoma and cholesteatoma. STUDY DESIGN: Case report. SETTING: Department of Otolaryngology, Head and Neck Surgery of Niigata University Medical and Dental Hospital, which is a tertiary care center, Niigata, Japan. PATIENT: A 43-year-old man demonstrated symptoms resembling those of cholesteatoma: facial palsy, gradually progressive hearing loss, and chronic draining of the right ear. Other objective findings also supported a finding of cholesteatoma, but a computed tomographic scan and magnetic resonance imaging scan showed a well-enhanced mass and extensive bony erosion in the middle ear. At surgery, a granulous tumor in the mastoid cavity was diagnosed as squamous cell carcinoma, and closely coexisting cholesteatoma was found. Surgical specimen demonstrated carcinoma and cholesteatoma in the same field. INTERVENTION: Radiation and chemotherapy were performed followed-up by mastoidectomy. CONCLUSION: Because middle ear carcinoma has a poor prognosis, it is important to detect lesions early. It is necessary to consider that middle ear carcinoma arises from not only chronic otitis media or surgical invasion but also from primary acquired cholesteatoma.     

Congenital cholesteatoma of the petrous pyramid

A 20-year follow-up was done on a patient with a large congenital cholesteatoma of the petrous apex. The patient was treated successfully with marsupialization through a radical mastoidectomy and sphenoid sinusotomy. Cranial computed tomography and magnetic resonance imaging demonstrated continued cholesteatoma growth. Bone-conduction thresholds remained normal despite replacement of the internal auditory canal by cholesteatoma matrix. The patient continues to have chronic otorrhea, but is otherwise asymptomatic.     

Diagnóstico radiológico de las condiciones no patológicas del ápex petroso

Many patients with otological symptoms are remitted to the otolaryngology outpatient clinics every day. These patients commonly undergo imaging studies, generally magnetic resonance imaging (MRI). In some cases, a positive unilateral result is found in the form of a potentially pathological signal that can be observed in the petrous apex region. We present the cases of 6 patients (aged between 26 and 62 years) with asymmetric bone marrow distribution or trapped mucous fluid secretions in the petrous apex, collected over a 6-year period. Diagnosis was made with the use of CT scans and MRI. All of the patients were referred for skull base surgery. In all cases a non-pathologic asymmetry was diagnosed in the petrous apex. Certain non-pathologic conditions of the petrous apex must be treated expectantly without any surgery.     

岩尖胆脂瘤的诊断与治疗

目的：讨论岩尖胆脂瘤的诊断与治疗。方法：总结了４例岩尖胆脂瘤的回顾性资料。结果：４例均有重度耳聋、眩晕、面瘫及慢性中耳炎病史，颞骨ＣＴ扫描作出诊断，并经迷路———耳蜗径路全部切除岩尖胆脂瘤。结论：认为颞骨ＣＴ扫描及ＭＲＩ对临床诊断及手术径路的选择有重要作用。经迷路———耳蜗径路为彻底清除胆脂瘤，处理面神经及脑脊液漏提供了最直接的通道     

Magnetic resonance with gadolinium DTPA for the investigation of temporal bone tumours

The membranous labyrinth and 7th and 8th cranial nerves are well shown by magnetic resonance scanning but the lack of bone detail makes MRI secondary to CT for the investigation of lesions of the petrous temporal bone. Twenty-two intrinsic temporal bone tumours were examined by magnetic resonance in this study. Seven glomus tumours, one facial neuroma and one carcinoid tumor received intravenous gadolinium DTPA. All showed signal enhancement although the practical value of this enhancement was variable. The ability of MRI to demonstrate the jugular bulb separate from a glomus tumour confined to the middle ear, and signal enhancement of another middle ear tumour after partial removal are described, as well as the tissue characterization for discriminating between cholesteatoma and cholesterol granuloma for mass lesions in the petrous apex.     

Can MRI Replace a Second Look Operation in Cholesteatoma Surgery?

The purpose of this paper is to investigate whether a magnetic resonance imaging (MRI) examination of the petrous bones could replace the conventional second look surgical procedure when a canal wall up tympanoplasty procedure has been performed during the first look surgery. Eighteen patients were examined with MRI prior to a second look surgical procedure. MRI was performed on a 1.5 T superconducting system. T2 weighted images before contrast and T1 weighted images after contrast (gadopentate dimeglumine) were obtained. Imaging results were compared with surgical findings. The poor radiosurgical correlation (50% and 61% after re-evaluation) suggests that, at the present time, MRI is not a valid alternative to a second look surgical intervention in the case of cholesteatoma treated by canal wall up tympanoplasty. In our study, MRI was not capable of differentiating small pearls of residual cholesteatoma from surrounding scar tissue.     

Radiographic diagnosis, surgical treatment, and long-term follow-up of cholesterol granulomas of the petrous apex

Cholesterol granuloma is an unusual lesion of the petrous apex. Accurate preoperative differentiation of the various lesions of the petrous apex by computed tomography scanning only has been difficult. We reviewed the clinical findings, computed tomography and magnetic resonance imaging scans, surgical approaches, and long-term follow-up in 10 patients with cholesterol granuloma of the petrous apex who were seen between 1971 and 1988. Headache and deficits of the 5th, 6th, 7th, and 8th cranial nerves were common presenting symptoms. Magnetic resonance imaging with special imaging techniques was accurate in diagnosing cholesterol granuloma in four patients preoperatively and three patients prior to revision surgery. The optimal surgical approach was chosen on the basis of clinical and radiographic findings and included the transsphenoidal, infralabyrinthine, transcochlear, and suboccipital routes. Our review reveals that magnetic resonance imaging is more specific than computed tomography in establishing a preoperative diagnosis and is also the technique of choice in follow-up. The long-term results are discussed.     

Invasive cholesteatoma of the old radical mastoidectomy

OBJECTIVE: The aim of this study is to show the importance of computed tomography scanning (CT) and magnetic resonance imaging (MRI) in ancient radical cavities and to determinate the risk factors of an invasive cholesteatoma recurrency. MATERIAL AND METHOD: We present 4 cases of medial invasion in the petrous bone of a cholesteatoma without specific symptomatology which appeared many years after undergoing radical mastoidectomy for an acquired cholesteatoma. CONCLUSION: The analysis of this series allowed to put in evidence the factors of suspicion of an underlying cholesteatoma. They are: the age, an aural discharge, numerous surgical interventions, immunodeficiency, cholesteatoma in childhood and antecedent of facial nerve palsy. This trial emphasizes the importance of imaging (CT and MRI) in front of an ancient radical cavity which presents one or some of these factors in order to eliminate a recurrence of an invasive cholesteatoma. Let us note that the demand of the patients is sometimes aesthetic or functional.     

Invasive cerebrospinal fluid cysts and cephaloceles of the petrous apex.

OBJECTIVE: To describe the presentation, diagnostic evaluation, and surgical management of petrous apex cerebrospinal fluid (CSF) cysts and cephaloceles. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Six patients with symptomatic CSF cysts or cephaloceles. INTERVENTION(S): All patients underwent operative intervention. MAIN OUTCOME MEASURE(S): Presentation, imaging characteristics, operative findings, surgical approach, resolution of symptoms, and complications. RESULTS: Six patients presented with various neurotologic symptoms including vertigo, otalgia, diplopia, meningitis, hearing loss, and retroorbital headaches. Four lesions were centered within the anterior petrous apex and were classified as a cephalocele originating from Meckel's cave. The remaining two lesions were arachnoid cysts that involved the posterior petrous apex. Cysts and cephaloceles both demonstrated bone erosion on computed tomography and were hyperintense on T2-weighted magnetic resonance imaging and isointense or hypointense on T1-weighted magnetic resonance imaging. A variety of surgical approaches was used to treat these lesions. Preoperative symptoms were improved in five of six cases. One patient developed a postoperative CSF leak that resolved with conservative measures. CONCLUSION: Petrous apex CSF cysts and cephaloceles may present with a variety of neurotologic symptoms. Imaging often helps narrow the differential diagnosis, but these lesions can still be confused with other erosive skull base lesions such as cholesterol granulomas, epidermoids, or tumors. Optimal treatment of symptomatic posterior petrous apex CSF cysts is marsupialization via a posterior fossa approach (i.e., retrosigmoid or retrolabyrinthine). A middle fossa approach with obliteration of the anterior petrous apex may be used to treat symptomatic CSF cephaloceles arising from Meckel's cave.     

Can MRI replace a second look operation in cholesteatoma surgery?

The purpose of this paper is to investigate whether a magnetic resonance imaging (MRI) examination of the petrous bones could replace the conventional second look surgical procedure when a canal wall up tympanoplasty procedure has been performed during the first look surgery. Eighteen patients were examined with MRI prior to a second look surgical procedure. MRI was performed on a 1.5 T superconducting system. T2 weighted images before contrast and T1 weighted images after contrast (gadopentate dimeglumine) were obtained. Imaging results were compared with surgical findings. The poor radiosurgical correlation (50% and 61% after re-evaluation) suggests that, at the present time, MRI is not a valid alternative to a second look surgical intervention in the case of cholesteatoma treated by canal wall up tympanoplasty. In our study, MRI was not capable of differentiating small pearls of residual cholesteatoma from surrounding scar tissue.     

Gd-DTPA-enhanced MR imaging of cholesteatoma]

It is sometimes difficult to differentiate a cholesteatoma from an accompanying cholesterol granuloma, mucosa, fluid and, especially, granulation tissue. This study was designed to assess the reliability with which cholesteatoma can be differentiated from such accompanying lesions by Gd-DTPA-enhanced MR imaging. Twenty-one patients with cholesteatoma were studied with magnetic resonance (MR) imaging. The cholesteatoma had intermediate to high signal intensities similar to those of granulation tissue, on both T1- and T2-weighted images. On Gd-enhanced images, however, there was marked enhancement of all granulation tissues while the cholesteatoma showed no such enhancement. Gd-DTPA-enhanced images distinguished cholesteatoma from granulation tissues and permitted determination of the exact extent of the cholesteatoma. Cholesterol granulomas showed high signal intensities on both T1- and T2-weighted images. Cholesterol granuloma can, therefore, be distinguished from cholesteatoma and granulation tissues on both T1- and T2-weighted images. Gd-DTPA-enhanced MR imaging is a valuable tool in the evaluation and management of cholesteatoma.     

Cholesterol cysts of the temporal bone: diagnosis and treatment

Cholesterol cyst (or granuloma) of the temporal bone, a recognized clinical entity distinct from cholesteatoma, is more common than previously thought. Apparently it is caused by obstruction of previously pneumatized temporal bone air cells. Surgical cure is achieved by drainage and reestablishment of normal pneumatization. This paper reviews 14 cholesterol cysts of the temporal bone, emphasizing the importance of preoperative imaging and surgical approach. Use of magnetic resonance imaging differentiates cholesterol cysts from cholesteatoma or other neoplasms. Computed tomography delineates the location of the lesion and defines temporal bone anatomy essential to surgical approach. The two studies together allow the surgeon to properly plan drainage, as in the case of a cholesterol cyst, versus excision or exteriorization, as in the case of cholesteatoma. The infralabyrinthine approach to a petrous apex cholesterol cyst is the procedure of choice when hearing preservation is desired.     

Inner ear dysplasia is common in children with Down syndrome (trisomy 21)

OBJECTIVES/HYPOTHESIS: Middle and external ear anomalies are well recognized in Down syndrome (DS, trisomy 21). Inner ear anomalies are much less frequently described. This study reviews inner ear morphology on imaging to determine the prevalence of cochlear and vestibular anomalies in children with DS. STUDY DESIGN: The authors conducted a retrospective review of imaging features of (DS) inner ear structures. METHODS: Fifty-nine sequential patients with DS with imaging of the inner ear were identified by a radiology report text search program. Quantitative biometric assessment of the inner ear was performed on patients with high-resolution computed tomography or magnetic resonance images of the petrous bone. Petrous imaging was performed for evaluation of inflammatory disease or hearing loss. Spinal imaging, which included petrous views, was performed in most cases to exclude C1 to 2 dislocation, a potential complication of DS. Measurements were compared with normative data. RESULTS: Inner ear dysplasia is much more common in DS than previously reported. Inner ear structures are universally hypoplastic. Vestibular malformations are particularly common and a small bony island of the lateral semicircular canal (<3 mm in diameter) appears highly typical. Additional findings in some patients were persistent lateral semicircular anlage with fusion of the lateral semicircular canal and vestibule into a single cavity, vestibular aqueduct and endolymphatic sac fossa enlargement, cochlear nerve canal hypoplasia, and stenosis or duplication of the internal auditory canal. Stenosis of the external meatus, poor mastoid pneumatization, middle ear and mastoid opacification, and cholesteatoma were common, as expected.     

Management of petrous apex lesions

Advancements in imaging pose new diagnostic and therapeutic dilemmas as smaller lesions in the relatively inaccessible regions of the petrous apex and clivus are identified. Differentiation of true pathology from artifact and anatomic variants is critical in management of these lesions. We describe our experience with five patients diagnosed with petrous apex lesions: three, cholesteatomas; one, cholesterol granuloma; and one, false-positive. Soft-tissue obliteration of the temporal bone defect with postoperative follow-up using high-resolution computed tomographic scanning and magnetic resonance imaging is proposed as an alternative to exteriorization.