T H E

BRITISH JOURNAL OF SURGERY

VOl. 59 AUGUST, 1972 No. 8

ORIGINAL PAPERS

FRACTURES OF THE FLOOR OF THE ANTERI0.R CRANIAL FOSSA THE SELECTION OF PATIENTS FOR DURAL REPAIR

BY ANTONY JEFFERSON AND GERALD REILLY DEPARTMENT OF NEUROLOGICAL SURGERY, THE ROYAL INFIRMARY, SHEFFIELD

SUMMARY I. A series of 87 patients operated on because of

subfrontal fractures is reported. In 73 of these a fistulous lesion (connecting the brain with the nose or the accessory air sinuses) was displayed and was repaired. Almost always a bifrontal exploration has been made, because the lesions were bifrontal in 43 per cent of cases. The mean follow-up period was 4 years; to date no instances of postoperative meningitis or rhinorrhoea have occurred.

2. Our experience suggests that cerebrospinal rhinorrhoea accompanying fractures of the facial bones (without fractures of the skull vault) can safely be treated conservatively.

3. Damaged brain adheres to the lips of the torn dura and permanently prevents natural healing, thereby creating a continuing threat to life. Con- sequently it is recommended that all frontal fractures lying below the hairline and all comminuted anterior temporal fractures should be referred for expert neurosurgical/neuroradiological assessment. This is because 42 per cent of the patients requiring operative repair were selected after tomographic studies of the anterior fossa; they had not presented with the classic criteria of cerebrospinal rhinorrhoea, intra- cranial air, or meningitis.

FRACTURES of the floor of the anterior cranial fossa which allow the intracranial contents to com- municate with the nasal cavity or with the accessory air sinuses are widely recognized to be potentially dangerous. This fact is known to every general surgeon, who will most probably expect a history of meningitis, cerebrospinal rhinorrhoea, or air within the skull to substantiate the diagnosis.

In an earlier communication (Jefferson and Lewtas, 1963) an instance was cited of an 18-year-old male who died of his first attack of pneumococcal meningitis without any preceding cerebrospinal rhinorrhoea. It was this event which first focused our attention on the potential dangers of these lesions. The intervening years have been marked by no exactly similar instances, although we have seen 42

cases from time to time which prove that pneumo- coccal meningitis (even when promptly treated) can still prove fatal. This subsequent period has also allowed us to accumulate more data and to crystallize our ideas. To our certain knowledge dangerous fractures exist in the absence of cerebrospinal

Table I.-AGE AND SEX OF THE PATIENTS IN THE PRESENT SERIES

" $ ~ f ~ ~ f P Male Female

0-10 2 I 11-20 18 4 21-30 16 2 3 1-40 21 41-50 I2 51-60 8 61-70 3 - -

Total 80 7

Table II.-REASONS FOR OPERATION IN THE PRESENT SERIES No. of

Reason f o r Operation Patients Radiographic 35 Initial trauma

Iq (e.g., compound fracture) Meningitis I1 Watery nasal discharge 19 Intracranial air 7 Exploration to confirm anticipated intact dura 2

Total 87 -

rhinorrhoea, intracranial air, or meningitis. We believe that it is possible to identify the majority of these lesions before serious complications develop. It is our purpose in this contribution to define how this may be done, for the need to detect and to repair the fistulous fracture remains as urgent as ever.

CASE MATERIAL The cases considered here are an unselected series

of 87 patients operated upon in the Department of Neurological Surgery, the Royal Infirmary, Sheffield, under the care of one of us (A. J.) over a 15-year period. The distribution according to age and sex is shown in Table Z, and the reasons for operation are listed in Table ZZ.

586

All except 8 patients underwent exploration using of some neurosurgeons, we have ample proof that the a bifrontal osteoplastic bone-flap (brief details of the resultant exposure of the sagittal sinus creates no operation are included below). The balance of the special hazards. operated patients had a unilateral bone-flap or a The dura is opened bilaterally and both subfrontal frontal trephine. (Exploration through a frontal regions are thoroughly inspected from within the trephine was used in 2 of the earliest cases as a means dura. All adhesions between pia-arachnoid and of confirming that no potentially dangerous lesion was present.)

A further 32 patients were considered as possible candidates for surgical repair but were rejected after appropriate study.

It should be noted that 30 per cent of the patients needing repair were referred without the possibility that a fistulous fracture might exist having been suspected.

OPERATIVE TECHNIQUE Because a bifrontal exploration has been proved

to be necessary in 43 per cent of the patients who required a dural repair, and because we have found

BRIT. J. SURG., 1972, Vol. 59, No. 8, AUGUST

Undamaged brain - dura will heal

Damaged brain adheres- dura never healr

Cortical

FIG. 2.-Left subfrontal region approached intradurally. The left frontal pole is held retracted. A funnel of brain is herniated into the dural defect, sharp dissection will be necessary to free this

-====-+4L& .vu: Dural scar (healing)

FIG. I .-Diagrams showing the circumstances under which the dura is able to repair itself.

B FIG 3 -A, Coronal tomogram. Note destruction of the left ethmoid roof. A soft-tissue shadow occupies the upper part of the ethmoid

sinus on the left. Talung the radiological and operative findings together t h s soft-tissue shadow must represent herniated brain tissue which is shown diagrammatically in 5.

no absolute method of identifying preoperatively those lesions which are bilateral, we recommend that a bifrontal exploration should be used rout- inely.

A coronal skin incision is made and a six-point bone-flap outlined. It is important to place the central bur holes exactly in the midline. While the bone-flap is being elevated the dura must be stripped carefully from the inside of the skull. In contrast to the views

dura are systematically divided using sharp dissection. Extensive probing of the dural defects can only serve to increase them and consequently we do not recom- mend it. A dural graft is necessary whenever a fracture (usually a comminuted fracture) is located lying within an area of defective dura and overlying either an accessory air sinus or the roof of the nose. The injured area on the cortex is covered with gelatin foam and a tissue graft is placed on the floor of the

JEFFERSON AND REILLY: ANTERIOR CRANIAL FOSSA FRACTURES 5 87

anterior fossa to cover the dural defect by a comfortably Fig. 3 illustrates the radiological correlate of this wide margin. In 85 per cent of the cases the tissue appearance. This radiograph was obtained in a used has been pericranium stripped from the bone- patient who had been injured 7 years preyiously and flap itself. Only when the amount of pericranial who was referred on account of headaches and mild tissue available is insufficient for the needs of the diplopia. He had never suffered cerebrospinal rhinor- situation is a graft of fascia lata employed. I t is in rhoea, meningitis, or been known to have had any the minority of cases (approximately 15 per cent) that sutures are necessary to hold the graft in position; as a rule one may rely on surface tension with confidence.

If the olfactory tracts have not been ruptured at the time of the accident it is usually necessary deliberately to divide one or both of them in order to ensure satisfactory positioning of the graft@). (Every effort is made to spare one olfactory tract, but if this is not possible there should be no hesitation about sacrificing it.) The blandness of the operation is shown by the results. The only postoperative death in this series was caused by bronchopneumonia in a man of 67 on whom we were forced to operate, in the

FIG. 4.-A, Anteroposterior radiograph of the skull. Note the small collection of air subdurally adjacent to the falx. B, Brow-up lateral radiograph of the skull. The sharp horizontal posterior outline of the main collection of air reveals this to be in the subdural plane.

face of a known chest infection, because of progressive drowsiness associated with an increasing collection of intracranial air. Moreover, there have been only 3 instances of postoperative complications (I haema- toma, I cerebral oedema, and I postoperative bone- flap infection in a case where the frontal sinus had been shattered by the accident). These complications all received appropriate treatment with a satisfactory outcome.

Apart from loss of olfactory function, there have been no instances of any neurological deficits following these operations.

PATHOLOGY Although the dura is able to repair itself, it is not

sufficiently recognized that when dura has been lacerated, and the overlying brain and arachnoid have also been injured, healing is permanently prevented by the damaged tissue which has adhered to the lips of the torn dura. When these circum- stances accompany a fracture in the roof of an air sinus a permanent potential path between the intra- cranial cavity and the external world will result. This concept is shown diagrammatically in Fig. I. The typical appearance of a herniated sleeve of brain and arachnoid as seen at operation is shown in Fig. 2.

FIG s.-Brow-up lateral radiograph of the skull. Note that air althou'gh diffusely scattered in the subarachnoid plane is con: centrated in the suprasellar region. This patient had :fracture involving the sphenoid sinus (see Fig. 11 A).

intracranial air. At operation a large wedge-shaped defect in the roof of the anterior part of the ethmoids was disclosed; it measured at least 0.5 cm. at its widest point and 2 5 cm. from front to back. The defect was closed using a pericranial graft.

BRIT. J. SURG., 1972, Vol. 59, No. 8, AUGUST

CLINICAL PRESENTATION of air reach the subarachnoid space (chiasmatic and From the clinical point of view the fractures with carotid cisterns) in exchange-

which we are concerned are usually considered under c. Intracerebraz--After the brain has become the following headings :- adherent to the fistulous lesion a sudden increase in

I. The presence of Intracranial Air.-Apart air pressure within the sinus or nose may result in the from any sagittal projections which may Seem explosive entry of air into the substance of the frontal appropriate, the radiographs which are essential in lobe. Such air splits the white matter, usually

causing remarkably slight neurological signs in spite of the size of the lesion. The fact that the air has penetrated the brain from the site where it has become ‘spot-welded’ to the region of the fistula is

B

FIG. 6.-A Tomogram of the skull with coronal cut through the ethmoid roof. Note ( a ) the disruptionofthe ethmoid roof on the left, and ( b ) the air-filled )stalk running from the ethmoid sinus into the left frontal intracerebral aerocele. 6, Explanatory line drawing traced from the original film and omitting the frontal sinus shadow.

FIG. 7.-Coronal tomogram of the skull, showing an extensive defect in the right ethmoid roof.

the study of post-traumatic intracranial air are those obtained using the brow-up lateral projeaion and a horizontal beam. Any air which is detected may be in one of four planes.

a. Suubdura2.-When air from an anteriorly placed subfrontal fistula gains access to the inside of the skull it can collect in the subdural plane if the damaged arachnoid has not adhered to the margins of the fistula. The amount of air in the subdural space may be minute, as in Fig. 4 A, or massive, as in Fig. 4 B.

b. Subarachnoid.-Subarachnoid air is relatively uncommon and is most likely to be found in quantity when the fracture involved the sphenoid sinus (Fig. 5). This is because cerebrospinal fluid drains very freely via this particular fracture and large amounts

FIG. S.-Diagram in which the shaded area outlines the region in which skull fractures may prove to be compound;,such fractures may cause the intracfanial caviry to communicate with the nose or an accessory nasal air sinus.

sometimes dramatically shown by the shape of the pattern of air, i.e., a clear-cut stalk may be seen running from the floor of the skull (Fig. 6).

d. IntruventricuZur.-Early after an injury air may reach the ventricles either when there is a very large amount of subarachnoid air or when a frontal intra- cerebral aerocele has ruptured into the anterior horn. As a delayed or late phenomenon following an extensive frontal lobe and subfrontal injury, air can enter the frontal horn directly from the fistula via a fairly short ‘corridor’ which is traversing an area of softened atrophic brain.

2. Cerebrospinal Rhinorrhoea.-Among our patients there were no more than 19 (22 per cent) in whom cerebrospinal rhinorrhoea was the factor initiating a dural repair. Copious rhinorrhoea is associated with fractures which involve the sphenoid sinus, fractures which have damaged the cribriform

JEFFERSON AND REILLY: ANTER

plate (where there is no brain to plug the opening), or when post-traumatic atrophy has allowed the lateral ventricle to empty directly into the fistula (see Intraventricular Air above). I n most other circum- stances rhinorrhoea is sporadic.

I t must be remembered that when there have been fractures which involve the accessory air sinuses (including the maxillary sinus) there may be a post- traumatic nasal discharge not easily distinguished from cerebrospinal fluid. Vasomotor rhinitis may cause diagnostic difficulties which can sometimes be

LIOR CRANIAL FOSSA FRACTURES 589

found to be necessary in every patient in whom preceding meningitis provided the reason to explorc the subfrontal fracture.

One case illustrates the dangers of accepting the diagnosis of pneumococcal meningitis (in the absence of a known pneumococcal septicaemia) with- out inquiring very closely into the patient’s past history.

Case I.-A male, aged 30 years, had been admitted under a general physician and received effective treatment for a proved pneumococcal meningitis I I months prior to

FIG. 9.-A. Anteroposterior radiograph of the skull, showing a comminuted left frontotcmporal fracture. 6, Tomographic cut in the coronal plane. C, Line drawing, traced from the radiographs. Note that the blow in the left anterior temple has dislocated the frontozygomatic suture (I) and, by displacing the lateral part of the orbital roof medially, has deformed the orbit (2) and has disrupted the left ethmoidal roof (3).

resolved simply by the administration of anti- histaminic drugs. (Indeed, there were 2 patients in this series whom we diagnosed retrospectively as suffering from rhinitis. Both of them had had frontal injuries but exploration showed no lesion and their nasal discharge persisted harmlessly at intervals for some years postoperatively.)

In patients whose watery nasal discharge is of doubtful origin isotope studies may be necessary. Crow, Keogh, and Northfield (1956) originally proposed the use of 24Na, but the substance more commonly used at present is 1311 (see, for example, Dietz, 1970). We have not felt the need to use this method extensively. I n our limited experience we have found 1311 scintiscanning of no value in demon- strating the actual site of the fistula. However, if cotton-wool plugs are placed in the nose of any patient with a watery nasal discharge and are examined for isotope concentration at 4 hours and at 24 hours after the lumbar injection of IOO pc. of lalI very useful information will be obtained. One may determine thereby whether or not the fluid is indeed cerebro- spinal fluid and one may gain an estimate of the rate at which it is being poured out. Some further remarks on cerebrospinal rhinorrhoea are found below in connexion with fractures of the middle third of the face.

3. Meningitis.-Eleven patients in this series underwent operation because of a preceding attack of meningitis. The responsible organism was the pneumococcus in 4 of them, while no organism could be isolated in the remainder. A dural graft was

C

being referred to one of us (A. J.) for a compensation claim. It transpired that his meningitis had commenced immediately following a fall on the buttocks, which could only be described as of moderate severity. It was incon- ceivable that such a relatively mild injury could have caused a fistulous fracture de nowo. However, pneumo- coccal meningitis developing without an obvious cause suggested that a previous head injury must have occurred. Initially he failed to recall any head injuries, but when pressed he remembered that he had in the past been involved in a fight in which he had been kicked and had sustained a black eye. This injury had not led to hospital admission nor had he been off work as a result of it, so the event had not impressed itself on his memory. Armed with this past history, tomograms of his skull were obtained (Fig. 7) and a defect was seen in the roof of the right anterior ethmoid with clear evidence of an associated right frontal skull fracture. At operation a large defect (8 x 4 mm.) was found in the roof of the right ethmoid; it lay within an even bigger area of defective dura (4 x 3 cm.). The brain was prolapsed into the defect. The prolapsed brain was cut free and the defect was closed with a peri- cranial graft. He has remained well thereafter.

One must assume that the fall on to the buttocks caused a tear of the scar tissue at the fistula sufficient to

590 BRIT. 3. SURG., 1972, Vol. 59, No. 8, AUGUST

allow pneumococci to penetrate from the ethmoid sinus into the subarachnoid space.

4. Radiological Studies including Tomo- graphy.-It has been our practice to regard with suspicion every patient with a fracture inferior to the hairline or with a comminuted fracture of the anterior temporal region (Fig. 8). This is because

FIG. 10.-Anteroposterior radiograph of the skull of a male aged 17 years, without previous rhinorrhoea, meningitis, or intra! cranial air. The severity of this fracture of itself indicates that a compound fracture must be present.

than those in the sagittal plane, but sagittal tomograms are sometimes diagnostic (Fig. 11).

5. Anosmia.-Preoperative examination showed that 19 of our patients had bilateral and 12 had unilateral anosmia. Although traditional clinical medicine attaches considerable importance to the presence of anosmia in the assessment of patients with fistulous subfrontal fractures, our experience has forced us to place little or no reliance on the presence of anosmia in the selection of patients for surgery. As an example one may cite a patient in whom bifrontal exploration showed the dura to be intact on the side on which olfaction was absent, and it was necessary to divide the functioning olfactory tract in order to effect a satisfactory repair on the other side. 6. Optic Nerve Injuries.-Unilateral damage to

the optic nerve was noted in 25 per cent of the patients, and in a further 2 per cent there was bilateral damage. In our series optic nerve injury has had no relevance to the selection of cases for surgical repair of the torn dura, so that although these injuries are of great interest and importance it is inappro- priate to discuss them further here. 7. Frontal Lobe Syndromes.-Florid frontal

lobe syndromes (e.g., apathy, personality disturbance, incontinence) occasioned by severe trauma to both

FIG. I I.-Same patient as in Fig. 5 . A, Tomographic cut in the sagittal plane clearly shows the fracture in the anterior wall of the pituitary fossa. 6, Sagittal tomographic cut through the anterior fossa, following recent head injury. Arrow marks the prominent up-ended sliver of bone.

either group may harbour a fistulous fracture involving the floor of the anterior cranial fossa. In the case of the anterior temporal fracture the danger is associated with the medial limits of the fractured area, which may extend up to (Fig. 9) or even across the midline in the floor of the anterior fossa.

There are occasions when the extent and position of the fractures shown on the plain radiographs make it indisputably clear that the floor of the anterior cranial fossa must have been disrupted (Fig. 10). However, only about half of the plain radiographs have spelt out a clear danger signal. For this reason we refer all patients suspected of a fistulous fracture for tomography. It is essential that the tomograms are obtained using individual cuts at 0.5-cm. intervals. Tomographic cuts in the coronal plane (see Figs. 3, 6 , 7, 9 B) are easier to interpret and more often useful

frontal lobes have occurred in 16 per cent of the patients. With I exception such patients have required a dural graft.

MIDDLE-THIRD FRACTURES Copious rhinorrhoea may sometimes occur with

fractures of the middle third of the face but with no fracture of the skull vault. (Intracranial air may also be found in such cases.) These events result from a split in the dura above the roof of the nose which differs from the other instances to which we have referred in one vital essential, which is that with every facial fracture the impact (and consequent acceleration/deceleration injury) has been partially absorbed by the crumbling of the facial skeleton. In consequence there is little likelihood of injury to the brain (cf. Fig. I). In these circumstances one may

JEFFERSON AND REILLY: ANTERIOR CRANIAL FOSSA FRACTURES 591

confidently predict that when reduction of the facial fracture leads to prompt cessation of the rhinorrhoea (or to rapid resolution of the intracranial air), then no further surgery will be required, for the dura will heal unimpeded by the interposition of pia-arachnoid and brain.

The truth of these contentions was impressed upon us after 5 patients with rhinorrhoea following fractures of the middle third of the face had been subjected to negative exploration of the floor of the anterior fossa. Following this experience we refer such patients for tomographs of the floor of the anterior fossa when the treatment of the facial fracture has been completed and the splints have been removed. If the tomographs confirm that the floor of the anterior fossa now appears to be intact the patients are discharged from further neurosurgical supervision. Follow-up of these patients has shown that they have all remained free from further rhinor- rhoea and from meningitis.

EFFICACY OF THE TREATMENT AND THE CASE SELECTION

The effectiveness of these intradural grafts is proved by the fact that so far we have not encountered any instances of postoperative meningitis or post- operative recurrence of cerebrospinal rhinorrhoea. The mean period of follow-up of the operated patients in this series is 4 years.

We have had the opportunity to study the late histological appearance of an intradural pericranial

Table III.-PATIENTS SUBJECTED TO NEGATIVE SURGICAL EXPLORATION IN THE PRESENT SERIES

No. of Reasons for Operation Patients

Rhinorrhoea with middle-third fractures 5 Rhinitis I Subdural air 2 Exploration to confirm anticipated intact dura 2

Misinterpretation of the radiographs (i.e., fistulous fracture falsely identified) 4 -

Total 14

graft in a patient with spontaneous cerebrospinal rhinorrhoea which arose from the chronic raised pressure of an intracranial tumour. Macroscopically the graft was seen to have adhered where it had been placed, and Fig. 12 shows it to have merged with the normal dura, re-creating a complete protective barrier against infection.

We have to admit that in evolving what we now regard as sound principles for the management of these patients we were initially guilty of excess enthusiasm. This caused 14 patients to be subjected to a negative surgical exploration. The reasons for these operations are shown in Table ZZZ.

We are naturally embarrassed to report an incidence of 16 per cent with negative findings at operation but we feel sure that the figure now would not exceed 5 per cent, for we have learned to reject the misleading middle-third fractures, and we know that small amounts of subdural air which resolve within z days may be ignored when the radiographs are normal. Two cases were explored 10 years ago, in the very early stages, when we wished to verify our predictions at a time when we were breaking new

ground. Finally, not only have we learned to read the radiographs more precisely, but also we have learned that only really first-class films may be relied upon. In the past 5 years a total of 37 patients under- went exploration and only z have provided negative findings.

FIG. 12.-Histological appearance of an intradural pericranial graft ( x IS) obtained 7 months after an operation made necessary by an intracranial tumour. Note that the grafted area has fused densely with the normal dura which is seen on the left.

With regard to the diagnostic weight which may be attached to a history of meningitis, intracranial air, or rhinorrhoea in the head-injured patient we have found as follows. Preceding meningitis is always (100 per cent) diagnostic of a fistulous fracture. Intra- cranial air has been misleading on z occasions out of the 7 in which it has been observed, whilst watery nasal discharge was misleading 6 times and diagnostic on 13 occasions (Table ZZZ explains how these ‘ false positives’ arose).

The justification of our criteria of case selection may be found in the fact that among the 73 patients who needed a dural repair no less than 31 were selected entirely because of the radiographic features of the skull fracture. In other words, 42 per cent of necessary operations were not based on the classic criteria of preceding meningitis, intracranial air, or cerebrospinal rhinorrhoea.

DISCUSSION The management of the particular variety of

compound skull fracture which is created by fistulous fractures in the floor of the anterior fossa has been gradually evolving over the years. Before the advent of antibiotics and before improvement in anaesthetic techniques neurosurgical procedures had a potential danger that probably equalled that of the fistulous fracture. It was thus originally reasonable for didactic authorities to recommend conservative treatment; that is to say, if cerebrospinal rhinorrhoea ceased, then operation could be avoided. However, it is generally agreed that such ‘healing’ of these fractures can be proved histologically at autopsy to be most unsafe (Line11 and Robinson, 1941). Dietz (1970) in his recent thorough review of the problem castigates such ‘healing’ as ‘ sham-healing’.

Our point of view is based firmly on that of Jefferson and Lewtas (1963)~ who said that one of the chief enemies of logical thought concerning fractures involving the frontal and ethmoid sinuses was that most published articles were concerned largely, if not wholly, with cases which at some time had beenknown

592 BRIT. 3. SURG., 1972, Vol. 59, No. 8, AUGUST

to have cerebrospinal rhinorrhoea, air within the skull, intracerebral abscess, or meningitis. If they lived long enough all cases with fistulous subfrontal fractures would eventually fit into at least one of these categories. However, because the infective complica- tions would not invariably respond to treatment they were convinced that the fistulous dural lacera- tions must be recognized before infection developed.

It is perhaps not generally recognized just how long the interval between injury and meningitis may be. In I of our own patients it was 24 years, and in a case recorded by Strenger (1958/9) it was 31 years. Thus, given a fistulous fracture the affected person simply has to go on living and sooner or later invasive bacteria (usually pneumococci) will penetrate the flimsy tissues at the border of the air sinus and the brain. Because the Department of Neurological Surgery at the Royal Infirmary, Sheffield, does not admit unselected patients with head injuries we can provide no meaningful figures concerning the number of affected patients. However, the observed frequency of cerebrospinal rhinorrhoea among large series of skull fractures is approximately 2 5 per cent (Lewin, 1954; Mincy, 1966; Raaf, 1967). Our own findings suggest that for every patient with a skull fracture and cerebrospinal rhinorrhoea there are two additional patients who harbour fistulous lesions which require repair. Utilizing the above figures one may compute that at least 7 per cent of patients with skull fractures require a dural repair. Whilst this figure may be excessive one must conclude at least that the fistulous fractures are sufficiently numerous to demand that those in charge of the head-injured patient are aware of the extent and nature of this particular problem.

If it be agreed that all these injuries should be carefully studied the means of detecting the fistulous lesions require a brief discussion. It must be made clear at the outset that the final case selection which involves specialized techniques and critical interpreta- tion of the radiological data is a matter for the specialist. Thus, the general or accident surgeon who can refer his patients to the neurological surgeon needs only to be aware of the problem, and we advise him to be guided mainly by the simple rule illustrated in Fig. 8 and to remember that the trauma may seem trivial to the injured individual (see the present Case I). Reverting to techniques of case selection, radiological methods provide the key to most of these; apart from the plain radiographs, tomographs (Dietz, 1970)~ or stereoscopic radiographs (Johnson and Dutt, 1947; Grote, 1966)~ subdural air injections have been proposed (Jefferson and Lewtas, 1963). However, we may report that over the years subdural pneumography, although still of occasional use, has been largely supplanted by ever more technically skilful tomography.

It was Eden (1942) who introduced the intradural approach which was taken up and whose merits were made so clear by Lewin (1954). We have always used the intradural approach because, in view of the anatomy of the lesions as depicted in Fig. I, it is a logical necessity to do so. Our results (ie., no recurrences to date) are not unique and they compare favourably with the 12 per cent recurrence rate (Adson and Uihlein, 1949) of the extradural approach.

Our management of this problem has been in most respects similar to that of Lewin (1966) although it is

probably the nearest of all to that of Dietz (1970). Lewin (1966) appears not to have looked for these lesions quite so aggressively as Dietz (1970)~ who believed that aZZ fistulous fractures must be picked out from among the general run of head injuries before the dangerous complications develop. It is interesting that among the dangerous complications we have encountered only I abscess. This was a small ' silent' lesion which was displayed during the course of a routine operation. (Its presence merely caused us to perform the operation in two stages.) Perhaps the rarity of abscesses in this series reflects one of the benefits of treating all patients at risk before the complications develop.

Unlike other series (cf. Dietz, 1970) we have encountered no patients with fistulous fractures associated with injuries of the intracranial portion of the internal carotid artery.

The views which we have adopted regarding rhinorrhoea or intracranial air associated with fractures of the middle third of the face without an associated fracture of the skull vault may not be uni- versally held, but we believe that time will show them to be valid. That such fractures seldom require a dural repair was also the view of Boering and Beks (1963).

The seeking out of the potentially dangerous fracture by the neurosurgeon backed by a skilled radiological department seems, as a policy, to have justified itself. As long as antibiotics cannot be relied upon to control every attack of meningitis aggressive surgery recommends itself when the surgical risks are negligible. We may conclude by recalling that the regime propounded here has made 31 vulnerable patients (who would otherwise have remained undetected and at risk) safe from the hazards of intracranial infection.

Acknowledgements.-It is a pleasure to record our very real gratitude to Dr. N. A. Lewtas for his radiological advice and opinion. We are also indebted to Miss J. M. Osborne and Mrs. K. Byron-Thomson for their skilled radiographic technique.

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(1956), Lancet, 271, 325. DIETZ, H. (I970), Die frontobasale SchudeZhirnverZetzung.

Berlin: Springer. EDEN, K. (1g42), Br. J . Surg., 29, 299. GROTE, W. (1966), in Proc. Int. Congr. Neurol. Surg.

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JOHNSON, R. T., and DUTT, I?. ( ~ g q ) , Br. J. Surg., War Surg. suppl. I , 141.

LEWIN, W. (I954), Br. J . Surg., 42, I. -- (1966), Management of Head Injuries, p. 164. London: Bailliere, Tindall, & Cassel.

LINELL, E. A. and ROBINSON, W. L. (1g41), J . Neurol. Psychiat., Lond., 4, 23.

MINGY, J. (1966),J. Trauma, 6, 618. RAAF, J. (1967), A r c h Surg., Chicago, 95, 648. STRENGER, H. H. (1958/9), Z. Hals- Nasen- u. Ohrenheilk., 7, 65.