Intracranial aeroceles as a complication of frontal sinus osteoma

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Intracranial A e r o c e l e s as a C o m p l i c a t i o n o f Frontal Sinus O s t e o m a C. H a r d w i d g e ,

B.M., and T. R. K. Varma, F.R.C.S.

University Hospital of Wales, Cardiff, Wales

Hardwidge C, Varma TRK. Intracranial aeroceles as a complication of frontal sinus osteoma. Surg Neurol 1985;24:401-4.

A case of an intracerebral aerocele as a complication of an osteoma in the frontal sinus is reported. The patient had been investigated 7 years earlier for three episodes of idiopathic nocturnal epilepsy. Roentgenograms of the skull at that time showed the presence of a small osteoma within the frontal sinus. Removal of the osteoma was undertaken via a bifrontal approach and repair to the dural defect was made with a temporalis fascia graft. Postoperatively, the patient made a good recovery but developed frequent focal left hemisphere epilepsy. It is our view that sinus osteomas that are incidentally found should be removed before complications arise. KEY WORDS: Intracranial aerocele; Frontal sinus; Osteoma

The presence of air within the intracranial cavity is well documented in the literature. Intracranial aeroceles are, however, usually reported after trauma with a fracture of the skull extending into one of the air sinuses and are often associated with cerebrospinal fluid fistulae [17,18,22,23,25,28]. They have also been described in the presence of long-standing hydrocephalus [3]. Previous authors have described intracranial aeroceles as a complication o f osteomas in the frontal sinus [2,5-8,10,13,19,21,26,30]. H e r e we present a case report of a young man who had an osteoma of the frontal sinus that was previously diagnosed as an incidental finding on roentgenograms and who subsequently developed an intracranial aerocele 7 years after the initial diagnosis o f an o s t e o m a in the frontal sinus. Case Report

A 25-year-old right-handed student was referred to our neurosurgical d e p a r t m e n t with a history of sudden onset of headache, vomiting, and dysphasia. Address reprint requests to: Mr. T.R.K. Varma, F.R.C.S., Department of Neurosurgery, University Hospital of Wales, Heath Park, Cardiff, Wales. © 1985 by Elsevier Science Publishing Co., Inc.

When a detailed history was taken, it was established that his first symptoms occurred 10 weeks prior to admission. H e had been taking part in a rugby training session, and when running down the pitch, experienced a squeaking noise in the front of his head. This was followed by a severe frontal headache on the left side, which was least severe with his head straight, made worse on flexing his neck, and most severe on extending his neck. The headache lasted 4 days. During the next 8 - 9 weeks, his parents noticed a definite change in his personality. H e was short-tempered and disinterested in his usual activities. They also noticed he had difficulty with his speech. H e attended a second rugby training session on the night of his admission. During this session, he again developed a severe frontal headache, but not preceded by the squeaking noise. The headache was associated with nausea, and he had difficulty in handling the rugby ball. N e i t h e r episode had been preceded by physical contact or blows to the head. On returning home, he was again noticed to have difficulty with his speech. His headache was still severe and by now he had started vomiting. H e was taken to the local casualty department, where roentgenograms of the skull showed the osteoma in the frontal sinus and the presence of intracranial air. H e was subsequently transferred to our department. The patient had a past medical history o f three nocturnal convulsions when aged 17 years, which were investigated elsewhere. An electroencephalogram showed a diffuse abnormality with no focal features. A roentgenogram of the skull at that time showed the presence of the skull osteoma within the frontal sinus, but this was not considered significant. H e was treated with phenytoin 100 mg nocte, which he continued taking with no recurrence of his epilepsy. H e also had pulmonary tuberculosis at the age of 21 years, for which he was treated with rifampicin, ethambutol, and isoniazide for 9 months. On admission his headache and vomiting had settled. General examination was normal and there was no asymmetry of his frontal bone or displacement of the orbital contents. Except for a mild expression dysphasia we 0090-~,019/85/$5.]0

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could not detect any neurological abnormality. In particular, his sense of smell was intact and we could not induce a cerebrospinal fluid leak. Roentgenograms o f the skull revealed a large osteoma in the left frontal sinus eroding the floor of the anterior fossa, with the presence o f intracranial air overlying the left cerebral hemisphere (Figures 1 and 2). Computed tomography showed the osteoma and the aerocele, which was lying within the left frontal lobe (Figure 3). At operation the left frontal region was explored through a bifrontal craniotomy. A needle was inserted through the dura mater and 20 mL o f air was aspirated from the frontal lobe. The dura mater was opened and the surface of the brain appeared normal. On retracting the frontal lobe a large, cauliflowerlike, marble-hard osteoma with a base of approximately 3 cm was seen arising from the posterior wall o f the left frontal sinus. Although the dura mater was disrupted, no tract was found for the entry of the air into the skull. A small associated mucocele was present. The osteoma was completely removed with a combination of bone nibblers and a highspeed air drill. The defect was covered with a graft of temporalis fascia. The cavity within the frontal lobe that held the aerocele was not examined. The patient made an uneventful postoperative recovery. Repeat roentgenograms of the skull (Figures 4 and 5) showed total removal of the osteoma and absence of intracranial air. The patient was discharged 10 days postoperatively. H e has, however, since then developed

Figure 1. Anteroposterior roentgenograms of the skull showing osteoma in the left frontal sinus and the presence of intracranial air.

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Figure 2. Lateral roentgenograms of the skull showing extrasinusal extension of the osteoma in the sinus.

focal left hemisphere epilepsy, confirmed on electroencephalography. Despite therapeutic doses of phenytoin and carbamazepine, he has continued to have relatively frequent epilepsy.

Discussion Intracranial aeroceles were first described at autopsy in 1884 by Chiari [9]. Luckett [22] was the first to describe the condition in life when the radiographs of a man struck by a tram car showed air in his ventricles. Dandy Figure 3. Computed tomography scan confirming the presence of the osteoma and showing the aerocele extending into the left frontal lobe.

Intracranial Aeroceles

Figure 4. Postoperative roentgenogram of the skull showing complete removal of the osteoma.

[11,12] seized upon the diagnostic potential and subsequently developed ventriculography and air encephalography. Aeroceles.after trauma and fracture of the skull extending into one of the sinuses or mastoid air cells are Figure 5. Postoperative roentgenogram of the skull showing complete removal of the osteoma.

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well described [ 17,18,22,25,28]. The mechanism of formation of an aerocele is c o m m o n to openings in the skull due to fracture, infection, or tumor. Such an opening would allow air to enter the extradural space. If the causative agent produces a tear or opening in the dura mater, entry is made into the subdural space. Further, the arachnoid may also be torn; this allows air to enter the subarachnoid space and also cerebrospinal fluid to escape. Finally, the underlying brain may be lacerated and this will provide a direct communication from the exterior to the brain substance. W h e n the intranasal pressure is raised, as by coughing, sneezing, or straining, air and perhaps infected nasal secretions may be forced upwards along the c o m m u nicating pathways, even into the brain itself. A type of "ball valve" may exist that allows air to pass through but prevents its return. The volume of air may then be increased by subsequent coughs, sneezes or strains until a pressure is developed that the brain cannot tolerate and symptoms develop [21]. Osteomas of the frontal sinus are said to be the most commonly encountered neoplasm of the frontal sinus [20]. M o n t g o m e r y [24] reviewed a series of 300 osteomas of the sinus reported in the literature and noted that 8 0 % of these were in the frontal sinus. Many of these osteomas were symptomless and were found accidentally or at p o s t m o r t e m examination. W h e n symptoms are produced, headache is the most c o m m o n complaint. Osteomas of the fronal sinus usually grow outwards and may penetrate the orbit and displace its contents. Sometimes they grow inwards and may produce neurological symptoms. In some of the cases reported [24], infection had spread through or around the osteoma into the cranial cavity, causing abscess formation or meningitis. H o w e v e r , it is very rare for air to enter through the osteoma to form an aerocele within the skull. These complications were identified by Cushing in 1927 [10] when he reported four interesting cases. O n e was a case of a simple osteoma, in which meningitis and death followed an operation in which the ethmoid cells were opened. Another was associated with an intracerebral mucocele, which was successfully removed. T w o others were complicated by the presence of aeroceles. Cushing developed the bifrontal approach to these tumors, and after success in using fascia lata to repair dural defects after meningioma surgery, he incorporated this with the removal of osteomas. This technique forms the mainstay of anterior fossa repair today. The need for removal of small osteomas within the frontal sinus has been a matter of some dispute in the literature. Lillie [20] expressed the view that small asymptomatic osteomas discovered as an incidental finding did not require removal unless definite symptoms and signs seem to demand such treatment. Hamstead

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[15] and Brunner and Spiesman [7] felt that only evidence of the expansion of an osteoma in the sinus is an indication for its removal. Teed [31] declared that removal should be carried out while the tumor is small rather than after the appearance of symptoms of extrasinusal extension. In the presented case the osteoma of the frontal sinus was noted 7 years prior to the patient's symptomatic presentation. Subsequent roentgenograms would have shown an increase in size, giving an indication for removal. Surgery at this stage would have been relatively easy and carried a lower morbidity. It would also have prevented the formation of a cerebrospinal fluid fistula and its subsequent complications. The significance of the patient's previous epilepsy is unclear. As the osteoma had in fact breached the pia mater and herniated into the frontal lobe, it seems likely his present epilepsy is related to cortical injury as a direct result of the osteoma. This complication might have been avoided if surgery had taken place prior to extrasinusal extension. The morbidity and mortality associated with frontal sinus osteoma, with or without extrasinusal extension, is significant [29]. However, the removal of small osteomas is relatively easy and the operation carries a low morbidity. It is our view that incidentally found osteomas of the frontal sinus should be tracked by serial roentgenograms and removed at an early stage if there are signs of expansion. This would avoid the risks and morbidity associated with extrasinusal expansion and later removal.

References 1. Alexander E Jr, Davis CH, Suwanwela C. Extradural aerocele. Case report. J Neurosurg 1982;56:96-8. 2. Armitage G. Osteoma of the frontal sinus with particular reference to its intra-cranial complications and with the report of a case. B r J Surg 1931;18:565-80. 3. Azzam NE, Miles J. Ventriculo-aerocele secondary to obstructive hydrocephalus. Acta Neurochir (Wien) 1978;44:237-41. 4. Baldnweck I, Mallet, Theverenard, Jouveau-Debrevil. Pneumatocele frontale interne au cours de l'dvolution d'un ost6ome du sinus frontal. Ann Otolaryngol 1934:657-68. 5. Bell FG. Intracranial pneumatocele (pneumatocephalus) associated with orbit ethmoidal osteoma. Aust N Z J Surg 1934;4:70-4. 6. Benjamins CE, Verbeek FALJ. Pneumatocele frontale interne et ost6ome du sinus frontal. Ann Otolaryngol 1936:881-92.

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7. Brunner H, Spusman IG. Osteoma of the frontal and ethmoid sinuses. Ann Otol Rhinol Laryngol 1948;57:714-37. 8. Campbell EH, Gottschalk RB. Osteoma of the frontal sinus and penetration of lateral ventricle with intermittent pneumoeephalus. JAMA 1938;111:239-41. 9. Chiari H. Z Heilk 1884;5:383. 10. Cushing H. Experiences with orbito: ethmoidal osteoma having intra-cranial complications with report of four cases. Surg Gynecol Obstet 1927;44:721. 11. Dandy WE. Ann Surg 1918;68:5. 12. Dandy WE. Arch Surg 1926;12:949. 13. Devic, Richard, Moreau. ,Apropos de deux cas d'arachno~dite spinale haute: Considerations cliniques et th6rapeutiques. Lyon Med 1938;161:723-30. 14. Elles W. The present state of frontal skull-base surgery. Laryngol Rhinol Otol 1982;61:42-7. 15. Hamstead BE. Osteomas of paranasal sinuses and the mastoid process, JAMA 1938;11 l: 1273-5. 16. Hanieh A. Chronic extradural haematoma and extradural aerocele. Case report. J Neurosurg 1979;51:118-9. 17. Jameson KG, Yelland JD. Surgical repair of the anterior fossa because of rhinorrhoea, aerocele or meningitis. J Neurosurg 1973;39:328-31. 18. Jelsma F, Moore DF. Cranial aerocele. Am J Surg 1954;87:437. 19. Kessel FK. Orbito-ethmoidal osteomata with intracranial complications: report of a case. Guy's Hosp Rep 1939;89:337-46. 20. Lillie HI. External operations on the frontal sinus. Am J Surg 1938;42:199-206. 21. Lister Reid W. Spontaneous intracerebral aerocele associated with osteoma of posterior wall of frontal sinus. Med J Aust 1966:352- 3. 22. Luckett WH. Surg Gyncol Obstet 1913;17:237. 23. Lunsford LD, Maroon JC, Sheplak PE, Falbin MS. Subdural tension pneumocephalus: a report of two cases. J Neurosurg 1979;50:525. 24. Montgomery WW: Osteoma of the frontal sinus. Ann Otol Rhinol Laryngol 1960;69:245. 25. North JB. On the importance of intracranial air. Br J Surg 1971;68:826-9. 26. Nowotnyk, Schuller A. Subduraler Pneumocephalus bei ethmoidalem Osteom (Status epilepticus letalis nach lumbaler Luftullung bei altem Morbus sacer). Rontgenpraxis 1936;8:107-8. 27. Paradis IL, Caldwell EJ. Traumatic pneumocephalus. A hazard of resuscitators. J Trauma 1979;19:61. 28. Pitt TT. Intracranial aerocele in facial injury. Med J Aust 1982;l:449-502. 29. Pool LS, PontanosJN, Drueger EG. Osteomas and mucoceles of the frontal paranasal sinuses. J Neurosurg 1962;19:130. 30. Tarczo NB, Slowik T, Mozolewskie, Ko'Sciuczyk A. Case ofparanasal sinus osteoma with cerebrospinal rhinorrhoea and pneumocephalus. Neurol Neurochir Pol 1980;14:449-52. 31. Teed RW. Primary osteomas of the frontal sinus. Arch Otolaryngol 1941;33:255-92.