1380 S.A. MEDICAL JOURNAL 11 December 1971 A 'Clear View of the N,eglected Mastoid Aditus

G. C. C. BURGER, M.MED. (RAD.D.), Department of Diagnostic Radiology, H. F. Verwoerd Hospital, Pretoria

SUMMARY By placing the head with the aditus vertical to the casette an X-ray tomographic cross-section of the aditus The aditus is the central link between the attic and the can be produced, which also allows the integrity of the . Its patency determines the course of middle fossa floor to be judged with more accuracy than middle infections. has been possible in the past.

S. Afr. Med. J., 45, 1380 (971).

It is possible to make a transverse tomographic 'cut' through the aditus of the ear and at the same time to

Fig. 1. Tomographic cross-section of the , labelled Fig. 3. Tomographic cross-section of the with a wire coil insert in a dry skull. with in position in a dry skull.

Fig. 2. Tomographic cross-section of the aditus in a dry Fig. 4. Tomographic cross-section of aditus in a patient. skull. -Date received: 16 November 1970. 11 Desember 1971 S.-A. MEDIESE TYDSKRIF 1381 demonstrate the thin bony layer which separates it from without the advantage of ever seeing the middle cranial fossa (Figs. 1 - 4). its floor in true tangent. One would hesitate to add yet another one to the lono list of radiographic views of the mastoid, but the aditus i;' after all, the passage which controls the course and out­ ANATOMY come of every inflammatory assault on the and mastoid. Radiology has been strangely silent about this An accepted authority on anatomy describes the aditus as central connection of the 'key area' of the mastoid. In our 'a large irregular aperture which leads backwards from whole array of standard views and sophisticat~d tomo­ the into the upper pan of an air-sinus graphs we have not a single glimpse of the shape of the named the tympanic antrum." The aditus is, of course, not aditus. We continue to worry over the integrity of the a mere opening but a passage of quite 3 - 4 mm in length,

Fig. 5. Owen's view of a dry skull with wire coii insert in Fig. 6. SchiiJer's view of a dry skull, with wire coil insert the aditus. in the aditus.

Fig. 7. Submento-vertical view of a dry skull with wire coil insert in the aditus. 1382 S.A. MEDICAL JOURNAL 11 December 1971

Fig. 8. Towne's view of a dry skull with wire coil insert in the aditus.

with corticated walls throughout. Triangular in section, TECHNIQUE the roof also forms a small part of the floor of the middle cranial fossa. The medial wall is formed by the dense bony O\ven, nearly 20 years ago, realized the importance of what capsule of the labyrinth, with the lateral semicircular canal he called the 'Key Area' (attic-aditus-antrum).' Owen did making a horizontal, longitudinal ridge in it. Laterally are not have the advantage of our refined tomographs. He the superficial . did well with the techniques available to him, but the Owen's view failed to gain universal popularity because the appearance was distorted and the interpretation thus troublesome. No non-tomographic view can possibly demonstrate the aditus end-on, nor do the conventional tomographs attempt it. The aditus roof, indeed the whole upper surface of the petrous is an inclined plane, sloping downwards and forwards by 25' - 30' with the base line. In addition, as it runs backwards the aditus inclines laterally at an angle of 25' - 30' with the sagittal plane. It is possible to obtain a tomographic cross section by extending the supine head by 25' and rotating it 25' to the side being examined. Centre to the base of the nasal septum where it meets the upper

Fig. 9. Lateral tomogram of a dry skull with wire coil Fig. 10. AP tomogram in dry skull with wire coil insert insert in aditus. in aditus. 11 Desember 1971 S.-A. MEDIESE TYDSKRIF 1383

lip. The anterior tomographic cut, at the level of the base of the not only shows the tympanic cavity as clearly as the semi-axial views, but demonstrates the incus and its long process which now lies parallel to the caselle (Fig. 3). More posterior cuts at 2 - 3 mm apart show the aditus in cross section and its walls in clear-cut tangent. The roof. which is also the middle fossa floor, is at last seen for the thin layer it really is.

I have allempted to determine the position and direction of the aditus as it is projected in the various conventional views, by placing in the aditus of a dry skull a small coil of wire prior to radiography. The results are shown in Figs. 5 - 11. Using the new cross-cut, we hope to be able to study the anatomical variations of the aditus, the possible in­ fluence of its size on cellular development of the mastoid and the clinical significance of radiological demonstration of the aditus.

I wish to thank Or W. A. F. Kenny, Medical Superintendent, H. F. Verwoerd Hospital, Pretoria, for permission to publish and Professor P. de Villiers, Professor in Diagnostic Radiology, H. F. Verwoerd Hospital and the Radiographers for their help as well a, Mr C. T. R. Marais, the Hospital photographer. REFERENCES .. I. Davies. D. V. and Coupland. R. E. (1960): Gray's A,I£IfOIllY. 34th ed.. Fig. 11. Semi-axial tomogram in dry SkUll with wire coil p. 1322. London: Longmans Green. insert in the aditus. 2. Owen. G. R. (1951): Trans. Amer. Owl. Soc.. xxx 1 9.

Boeke Ontvang • Books Received

Sociology in Medicine. 2nd ed. By M. W. Susser and W. Inflammation, Immunity and Hypersensitivity. Ed. by H. Z. Watson. Pp. x + 468. R6,60. London and Cape Town: Movat, M.D., Ph.D. Pp. ix + 627. $27.50. New York: Oxford University Press. 1971. Harper & Row. 1971.

Clinical Chemical Pathology. 6th ed. By C. H. Gray, D.Sc., Regulation of Gluconeogenesis. Ed. by H.-D. Soling and B. M.D., F.R.C.P., M.R.C.S., F.R.I.C., ER.C. Path. Pp. x + Willms. Pp. xi + 347. Illustrated. DM. 46,-. Stuttgart: 244. £2.00. London: Edward Amold. 1971. Georg Thieme Verlag. 1971.

Methods of Ossiculoplasty. By J. R. Tabor, 1:{.D., EA.C.S. The Care of Hand Infections. By J. Sneddon, M.D. Pp. vii + Pp. ix + 88. Illustrated. $6.75. Springfield, Ill.: Charles C. 88. Illustrated. £1.30. London: Edward Arnold. 1970. Thomas. 1971. Kliniese Fisiologie van Sykamer Ondersoeke. Deur H. P. Wassermann, B.Sc., M.Med., M.D. Pp. viii + 142. R3.00. Hospital Staff Management. By M. W. Cuming, M.A. Pp. 247. Stellenbosch: Universiteits-Uitgewers. j 971. R5.70. London and Johannesburg: Heinemann & Cassell. 1971. Fundamentals of Ear Tomography. Ed. by J. Jensen and H. Rovsing. Pp. xiii + 221. Illustrated. $19.00. Springfield, Discoveries in Biological Ps,Ychiatry. Ed. by E J. Ayd, jnr, Ill.: Charles C. Thomas. 1971. M.D., EA.P.A. and B. Blackwell, M.D., D.P.M. Pp. 234. £3.25. Oxford: Blackwell Scientific PUblications. 1971. Introduction to OccupationaJ Therapy. By S. W. Mountford, M.A.O.T., T.Dip. Pp. viii + 208. Illustrated. £1.75. Edin­ Clinical Rheumatology. By J. A. Boyle, M.D. (Glasg.), burgh and London: E. & S. Livingstone. 1971. M.R.C.P. (Edin.), M.R.C.P. (Lond.) and W. Watson Buchanan, M.D. (G1asg.), F.R.C.P. (Edin.), F.R.C.P. Autogenic Therapy. Vol. V. By W. Luthe, M.D. Pp. xiii + 344. (Glasg.). Pp. xii + 587. Illustrated. £12.00. Oxford: Black­ Illustrated. $17.50. New York and London: Grune & well Scientific Publications. 1971. Strallon. 1970.