George T. Nager

LXXXIII The Arteries of the Human Middle Ear, with Particular Regard to the Blood Supply of the Auditory Ossicles:

Previous accounts of the sources of blood to the several parts of the middle ear have been based almost entirely on specimens in which attempts, often only partially successful, had been made to fill the vessels with colored material. Exposure of the various regions of the specimens, for observation, has been by dissecting away the overlying structures; and the observations themselves have been made either by the unaided eye or by means of the very low magnifications afforded by a hand lens or a dissecting microscope.

Cholesterol Granuloma Involving the Temporal Bone

The cholesterol granuloma does not represent an independent clinical or pathological entity, rather it is a term used for the description of a tissue response of the temporal bone, to the presence of a particular foreign body, i.e., cholesterol crystals. Three factors are considered to play an important role in its development: 1) interference with drainage, 2) hemorrhage, and 3) obstruction of ventilation. The cause of the initial hemorrhage may be a hemorrhagic inflammation or diathesis, a trauma or some other form of vascular disorder. Interference with air exchange and clearance can be caused by: tubal blockage, persistent mesenchyme, polypoid changes, scar formations, tympanosclerosis, cholesteatoma, etc. The cholesterol granuloma may develop in any portion of the pneumatic system of the temporal bone and it can be associated with a variety of middle ear disorders. Its principal precursor is the chronic middle ear effusion or serous otitis media. Its clinical expression and hallmark is the “idiopathic hematotympanum,” the dark bluish discoloration of the tympanic membrane. Osteitis and bone erosion are manifestations of an unusual, more advanced stage. Resorption of bone, in a rare instance, may lead to extensive destruction of the temporal bone.

Meningiomas invading the temporal bone with extension to the neck

Meningiomas are the second largest group of brain tumors after gliomas. They account for 13 to 18 per cent of all primary intracranial neoplasms. The majority occur in the cerebral chamber; only 8 to 9 per cent are located in the cerebellar chamber. Meningiomas are hamartomatous, not truly neoplastic tumors, which arise from dural fibroblasts and particularly from arachnoid cells that tend to cluster around the tips of the arachnoid villi. Their preferential sites correspond closely with the locations where arachnoid villi are most frequently encountered, namely, along the major venous sinuses and their contributory veins, at the foramina of exit of the cranial nerves, and where arachnoid cell clusters are found within the trunk or the perineural sheaths of cranial nerves within or adjacent to the basal foramina. Of all intracranial meningiomas, 20 per cent eventually develop an extracranial extension. These extracranial extensions project, in order of decreasing frequency, to 1) the orbit, 2) the external table of the calvaria, 3) the nasal cavity and paranasal sinuses, and 4) the parapharyngeal (cervical) space. Once a meningioma has gained access to the temporal bone, its tendency to extend beyond the confinements of the skull increases to 43 per cent. The most frequent pathway is through the jugular and lacerate foramina into the parapharyngeal space, where it may manifest as a nasopharyngeal, oropharyngeal, retromaxillary, retromandibular, or cervical neck mass. A meningioma in the parapharyngeal area can represent 1) an extracranial extension of a primary intracranial tumor, 2) a neoplasm arising in the jugular foramen, 3) a neoplasm originating from an arachnoid cell cluster within the trunk of a cranial nerve or its perineural sheaths within or near a neural foramen, or 4) a metastasis to a cervical lymph node from a primary intracranial meningioma. Meningiomas extending to the neck are unique because of their tendency toward extracranial expansion, higher incidence of local recurrence, multicentric growth, and frequent combination with other neoplasms of the central nervous system. They are frequently an expression of the central form of neurofibromatosis (von Recklinghausens disease).

Neurinomas of the trigeminal nerve

Trigeminal neurinomas account for about 0.2 per cent of all intracranial tumors and for about 2 to 3 per cent of all intracranial neurinomas. Trigeminal neurinomas occur most frequently in persons in the middle decades of life, with the highest incidence between the ages of 38 and 40 years. They show no sex predilection. Although very rare, trigeminal neurinomas are of considerable interest to the neurotologist because of their relation to the temporal bone, skull base, sphenoid and maxillary sinuses, nasopharynx, infratemporal fossa, and, in rare instances, the oral cavity. In addition to producing disturbances of fifth nerve sensory and motor function, these tumors are often associated with other symptoms, such as occlusion of the eustachian tube (sensation of fullness and conductive hearing loss), otalgia, exophthalmos, paralysis of the third, fourth, and sixth cranial nerves, and signs of posterior fossa involvement (sensorineural hearing loss, tinnitus, cerebellar ataxia, and involvement of cranial nerves VII and IX through XI), any of which may be the initial clinical manifestation of the neurinoma. Symptoms depend on the site of origin and course of development. Bilateral trigeminal neurinomas are a manifestation of the central form of neurofibromatosis.

Paget's Disease of the Temporal Bone

Osteitis deformans Paget is a fairly common, heritable, sometimes progressive disease of bone which affects primarily the axial skeleton and may lead to deformity and weakness. It affects 3% of the population over forty years of age and males more frequently than females. The skull and temporal bones become involved in about two-thirds of the patients. Progressive involvement of the temporal bones may lead to alteration of position, increase in size and change of architecture of the petrous pyramid, external canal, middle ear and inner ear capsule. These changes in turn may produce impairment of hearing (about 30–50% of cases) and vestibular function (20–25%). The clinical, radiological, and pathological manifestations of Pagets disease of the temporal bone are discussed in detail and explained with photomicrographs. Examples of tumor formations and vascular changes are presented.

Fibrous dysplasia of the temporal bone update with case reports

Fibrous dysplasia is a fairly common, well demarcated, misdifferentiation of the bone-forming mesenchyme affecting a single, several, or many bones, in which skeletal changes are the salient feature, but in which certain endocrinopathies, abnormal pigmentation of skin and mucous membranes, and occasionally other abnormalities form part of the entire disease process. The clinical and pathological aspects of the disease and its involvement with the temporal bone have been previously discussed. Two recent case histories are added here.

The jugular bulb in otologic surgery: anatomic, clinical, and surgical considerations.

The jugular bulb varies widely in position and dimensions. In certain pathologic conditions there is an increased incidence of jugular bulb enlargement, but such enlargement also occurs without an obvious underlying cause. Jugular bulb enlargement may lead to clinical symptoms for the patient and particular difficulties for the otologic surgeon, not only in the middle ear but also in neurotologic approaches. The different clinical aspects and problems associated with jugular bulb enlargement are discussed with illustrative cases and temporal bone histologic findings.

Osteogenesis Imperfecta of the Temporal Bone and its Relation to Otosclerosis

Osteogenesis imperfecta (OI) designates a heterogeneous group of heritable disorders of connective tissue that in addition to bone may affect tendons, ligaments, fascia, skin, sclerae, blood vessels, teeth, and hearing. The current classification identifies at least four major syndrome groups or types. It also recognizes a considerable number of additional syndromes that may represent supplementary types or subgroups. Loss of hearing is the least constant of the prominent features of OI. Its incidence varies between 26% and 60%. In OI, formation and remodelling of bone are variously affected. In the temporal bone the development of the inner ear capsule may be involved severely. In the stapes the disturbance in lamellar bone formation can lead to extreme thinness, dehiscence, and nonunion of the stapedial superstructure with the footplate. Osteogenesis imperfecta can be associated with otosclerosis, another bone dysplasia with a different morphology. Otosclerosis, in turn, may interfere with sound conduction and perception. Thus, the hearing loss encountered in OI may be the result of OI, otosclerosis, or a combination of both.

Relationship of the Utriculus and Sacculus to the Stapes Footplate: Anatomic Implications for Sound- and/or Pressure-Induced Otolith Activation

One hundred thirty human temporal bones that were sectioned in the vertical plane were examined to evaluate the relationship between the stapes footplate and the otolith organs. The shortest distance between the footplate and the utriculus was 0.58 ± 0.10 mm in the posterior third of the oval window, 1.04 ± 0.20 mm in the middle third, and 1.51 ± 0.20 mm in the anterior third. The distance from the sacculus to the footplate was 1.33 ± 0.20 mm in the middle third of the oval window and 1.31 ± 0.18 mm in the anterior third. Membranous connections extending between the utriculus and the footplate were found in 26% of temporal bones. These membranous connections in coexistence with additional anatomic factors such as stapes hypermobility and/or dehiscence of bone within labyrinthine structures may predispose patients to sound- and/or pressure-induced otolith activation. The findings may have implications for different causes of the Tullio phenomenon.

Arachnoid granulations of the temporal bone: a histologic study of dural and osseous penetration.

Hypothesis: Arachnoid granulations (AG) are more prevalent along the middle fossa surface of the temporal bone, where they produce larger bony defects than those occurring on the posterior surface. Background: Dural and bony defects formed by AGs are proposed to lead to spontaneous meningoencephaloceles and cerebrospinal fluid otorrhea. They most commonly occur at the tegmen and in individuals older than 40 years. Methods: Vertically sectioned temporal bones were evaluated using light microscopy to determine AG histology, distribution, and morphometry and to determine the prevalence of AG penetration in the donor population. Results: AGs were observed to penetrate the dura mater and make direct contact with cortical surfaces in 12.7% of donors in the Johns Hopkins Temporal Bone Collection. AGs occurred at middle fossa sites 13% more frequently than at posterior fossa sites. At middle fossa sites AGs produced significantly larger bony openings and were more likely to be associated with herniating brain tissue. Donors with AGs were significantly older, and all were in the late 30s or older. Conclusion: Erosion of the temporal bone by AGs is not a rare occurrence in the population and becomes increasingly prevalent with age. It is estimated that 14 in 1,000 donors were at greatest risk of eventual cerebrospinal fluid leakage at the tegmen. The age and anatomic distribution described in this study strengthens the notion that AG penetration plays a role in the pathophysiology of spontaneous cerebrospinal fluid leaks and meningoencephaloceles of the temporal bone.