Course of the facial nerve in congenital ear deformities. Tomographic demonstration

Aberrant pathways of the facial nerve through the temporal bone are related to the severity and type of congenital ear deformity. A facial nerve crossing the middle ear cavity with no bone covering cannot be shown by radiologic techniques but may be inferred from: (1) abnormalities of the first part of the facial nerve canal in the region of the geniculate ganglion, (2) absence of the Fallopian canal, (3) absence of the oval window, (4) absence of the pyramidal eminence, and (5) an exit foramen through the floor of the middle ear. Demonstration of these features is discussed with tomographic and histologic correlation in 2 cases, tomographic and surgical correlation in 31.

The demonstration of cartilaginous involvement in laryngeal carcinoma by computerized tomography

Thirty-six patients with laryngeal carcinoma were investigated by computerized tomography (CT). In 8 patients invasion of cartilage was shown at subsequent pathological examination of the excised larynges. In all there were 14 areas of cartilage involvement, 11 of which could be diagnosed on retrospective examination of the CT scans. Involvement of tumour was shown either as areas of decreased density (chondrolysis) or areas of local increased density (chondrosclerosis) due to cartilage ossification. False positive and false negative evidence of cartilage involvement was recorded in the series, but the accuracy of diagnosis in positive terms was approximately 79%. Histological evidence is put forward that the presence of carcinoma in relation to the cartilage produces perichondritis, which enhances ossification and the latter process may then in itself facilitate invasion by the tumour. Previous radiotherapy may also be a factor in the causation of the perichondritis and ossification.

Ear deformities associated with the Klippel-Feil syndrome

Congenital spinal fusion, constituting the Klippel-Feil anomaly, has long been known to be associated with severe deafness in many patients. Ten such cases are described, with audiometric and tomographic assessment of the ear lesions. Of the 20 ears examined, 12 showed evidence of severe hearing loss and of these, 11 had evidence of significant inner ear dysplasia on tomography. Middle and external ear abnormalities were also demonstrated. The significance of these findings and the relation to other syndromes is discussed.

The radiology of carcinoma of the ear

Carcinoma arising in external auditory meatus, middle ear cleft or mastoid cavity has a poor prognosis unless treated at an early stage. Biopsy of any suspicious tissue is the key to early diagnosis but there are radiological features which may suggest the presence of a malignant neoplasm. An important role of radiology is the demonstration of the extent of disease and of spread beyond the confines of the temporal bone. The optimum regime of surgery and radiotherapy cannot be planned without this information. The radiological features of 47 aural carcinomas were reviewed. Thirty-two of the cases were examined by multidirectional tomography and six by computed tomography. The modes of spread of the neoplasm are discussed as well as the differential diagnosis. It is concluded that high resolution CT is now the optimum method of demonstrating tumour spread in the axial plane and frequently also in the coronal section. Lateral tomograms are necessary to show erosion of the walls of the external auditory meatus. Erosion of the bony septum separating the middle ear cavity from the carotid canal can be shown on coronal sections and is an important sign of spread anteriorly. Soft tissue extension into the infratemporal fossa may be demonstrated by high resolution CT.

The ear deformities in mandibulofacial dysostosis (Treacher Collins syndrome)

Bilateral conductive deafness is common in mandibulofacial dysostosis with or without atresia of the external auditory meatus. This deafness is due to a wide range of deformities of the ossicular chain associated with a characteristic reduction in the size of the middle ear cavity. The attic and antrum are particularly affected and usually have a slit-like appearance on coronal section tomograms. The inner ear is essentially normal. The tomographic appearances of 44 ears from 22 patients with mandibulofacial dysostosis are described as well as the operative findings in 14. These were correlated with induced ear deformities in an animal model that had features characteristic of human mandibulofacial dysostosis. A review of the findings in the animal model suggests a very close correspondence with the human ear anomalies described at radiological investigation, operation and post-mortem examination. The lesions are largely symmetrical and this, with the characteristic slit attic, helps to differentiate mandibulofacial dysostosis from lesions with different aetiology but similar features such as facial microsomia. The prospects for surgical correction of the deafness in mandibulofacial dysostosis range from very good in mild cases with ossicular discontinuity, to poor where there is severe atresia. The importance of tomograms at an early age is stressed.

The radiology of cholesteatoma

The diagnosis of most cholesteatomas of the middle ear is made by direct examination of a perforation in the eardrum, and the only radiological investigation necessary for these patients is a set of plain petro-mastoid views. Of these the lateral with caudal tilt of the tube is the most useful, since it demonstrates the extent of pneumatisation and the position of the lateral sinus and middle fossa dura. The radiographic appearances do not generally affect the surgical approach or the course of the operation which must be exploratory. Nevertheless multidirectional or computerised tomography can demonstrate the soft tissue mass of a small cholesteatoma as well as the typical attico-antral erosion and ossicular displacement and destruction that occur. Tomographic investigation is needed when the diagnosis is in doubt, as when the eardrum is obscured, or when complications develop, but should not cause delay in instituting necessary surgery. For the rare congenital cholesteatoma in or close to the petrous pyramid with an intact eardrum, tomographic studies are essential to show the extent of the bone erosion, and to plan the surgical approach. The appearance of a smoothly outlined expansile lesion in the petrous pyramid may be almost pathognomonic, especially if this is shown to have low attenuation values after contrast enhancement. The role of high resolution CT in these cases is discussed.

Temporal bone studies in anencephaly

The principal anatomical and histological features of the temporal bones of three anencephalics are described, one a twin-headed monster, with four temporal bones. These may be summarized as follows: Malformation of ossicles. Mondini type malformation of the cochlea. Occasionally cochlear hydrops or collapse of Reissner's membrane, following apparently on its rupture. Distension of the vestibular labyrinth and oedema of the perilymphatic spaces and membranes. Rupture of the saccular wall with 'sealing off' and repair of the tears and gaps by coagulated lymph material. Fibrous obliteration of the internal auditory meatus containing scanty nerves and neurones. Geniculate ganglion and facial nerve present and appear to be normally developed. The neuro-epithelial structures were well developed despite the total or partial absence of the central nervous system. The temporal bones of anencephalics offer an excellent source of comparative anatomy for the study of the pathology of Menière's disease and sensorineural lesions.

High-resolution computerized tomography of the petrous bone

High-resolution computerized tomography (CT) has been used to investigate abnormalities of the ear and petrous bone. Congenital, traumatic, infective and neoplastic lesions have been evaluated in 30 patients with proven pathology. Some bone changes including abnormalities of the auditory ossicles have been better demonstrated than by conventional tomographic technigues, and high-resolution CT has some advantages in demonstrating both soft tissue abnormality and bone changes in the middle ear in primary neoplastic disease and secondary cholesteatoma. The absence of any practical means of taking sagittal sections with the present scanner design limits the usefulness of high resolution CT of the petrous bone, but this study has shown that the technique may now take its place as an important complementary procedure to pluridirectional tomography.

The demonstration of the auditory ossicles by high resolution CT

The high resolution CT scanning system introduced by EMI in 1978 has added a new dimension to computerised tomography in otology. The apparatus used for this study was an EMI CT 5005 body scanner adapted for head and neck scanning and incorporating a high resolution facility. The latter has proved most advantageous in areas of relatively high differential absorption, so that its application to the demonstration of abnormalities in the petrous temporal bone, and in particular middle ear disease, has been very rewarding. Traumatic ossicular disruptions may now be demonstrated and the high contrast of CT often shows them better than conventional hypocycloidal tomography. The stapes is also better visualised and congenital abnormalities of its superstructure have been recorded. These studies have been achieved with a very acceptable level of radiation to the eye, lens and cornea and the technique is clearly a rival to conventional pluridirectional tomography in the assessment of the petrous temporal bone. With further design improvements high resolution CT could completely replace existing techniques.

Radiology of the ear in mandibulo-facial dysostosis--Treacher Collins syndrome

Deformities of the external and middle ear with conductive deafness are common in mandibulo-facial dysostosis but cochlear function is nearly always normal. Twelve patients with the typical appearance and characteristics of the lesion are described. All had some degree of atresia of attic and antrum with absent or deformed ossicles but 4 had external auditory meatuses of normal calibre. The characteristic tomographic appearances of the ear are described.

The surgery of congenital deafness

This paper outlines the indications for surgery of congenital deafness in complete meatal aplasia, the methods of audiological and radiological assessment and an operative technique used in ten ears. It is felt that otologic surgery should be done before the pinna reconstruction as it is very important to try and introduce sound into these children at an early age. In addition, the position of the new auricle can be made more satisfactorily around an already established meatus. The value of tomography of the internal as well as the middle ear is stressed and the necessity for providing a stable and uninfected meatus emphasized with regard to the possible fitting of a hearing aid.

Anatomical findings in congenital conductive deafness

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Congenital deformities of the middle and external ear

Congenital deformities of the external and middle ears were shown by tomography in 246 patients. Surgical exploration has been undertaken at some time in many of these ears. The appearance of the tomograms and their significance were reviewed in the light of the operative findings and the authors' experience of congenital ear lesions. In nearly every case a middle ear cavity could be demonstrated although this varied from a normally aerated middle ear and mastoid in association with an isolated unilateral atresia of the external auditory meatus to a small slit-like hypotympanum in patients with craniofacial abnormalities. The ossicles were nearly always present but deformed. The typical appearances of the ossicles and the frequently aberrant pathways of the facial nerve are described.

Nasal encephalocoeles associated with unilateral absence of the cochlea

A case of nasal encephalocoele associated with unilateral absence of the cochlea is described. The association of congenital abnormalities of the skull and the spine with deformities of the inner ear is discussed together with the value of tomography in the assessment of these children.

Coils of the cochlea

Abnormalities of the cochlear portion of the bony labyrinth may often be suspected but are inadequately demonstrated by conventional tomography in the antero-posterior position. Further views are necessary. The authors demonstrate this by means of a comparison between tomographic and histological sections of the inner ear of an anencephalic with a unilateral Mundini defect. Submento-vertical tomograms give a good demonstration of the cochlea.

Hearing in patients with congenital deformity of the inner ear

Congenital abnormalities of the bony labyrinth and internal auditory meatus range from complete absence to minor anomalies compatible with normal cochlea function. A 'follow-up' survey to assess the hearing of 56 patients with abnormalities of the inner ear shown by tomography was made. The hearing levels are discussed in relation to the tomographic appearances and comparison made with other series of inner ear abnormalities demonstrated both radiographically and histologically.

Deformity of the labyrinth and internal auditory meatus in congenital deafness

In congenital deafness it is important that the radiological examination should exclude any deformities of the bony labyrinth or internal auditory meatus as well as demonstrating lesions of the middle and external ears. Radiological assessment of inner ear abnormalities should be used as a guide both to the feasibility of reconstructive surgery to the middle and external ears and for the future training of the child. Inner ear abnormalities demonstrated by tomography in 56 patients are discussed in relation to the cochlea function. The importance of demonstrating the central bony spiral of the cochlea and of assessing the size and shape the internal auditory meatus is stressed.