April 1991 tion, we need to be cognizant of the fact that these carry certain risks that can be severe at times. The authors also point out that initially this lesion appeared to be a pure high-flow fistula, but, in fact, after their stepwise therapy, it was demonstrated to be 0148-396X/91/2804-0623$03.00/0 NEUROSURGERY Copyright © 1991 by the Congress of Neurological Surgeons INTRACRANIAL ARTERIOVENOUS FISTULA 623 a mixed lesion requiring more aggressive ablative therapy than initially thought. J. Parker Mickle Gainesville, Florida Vol. 28. No. 4. 1991 Printed in U.S.A. Infected Intracranial Aneurysm in an Infant: Case Report Peter Cyril Whitfield, B.M., and Ross Bullock, Ph.D. F.R.C.S.(SN) University Department of Neurosurgery, Institute of Neurological Sciences, Southern General Hospital, Glasgow, Scotland The case of a ruptured, infected intracranial aneurysm occurring in a 34-day-old child is reported. The child was brought for examination after a sudden onset of screaming and pallor, followed by focal seizures. Blood cultures grew Staphy- lococcus aureus, and a computed tomographic scan revealed a large hematoma in the region of the left sylvian fissure. An angiogram demonstrated a 17-mm aneurysm arising from a small branch of the middle cerebral artery. At craniotomy, the hematoma was evacuated and an infected aneurysm was removed. The etiology, pathogenesis, and management of infected intracranial aneurysms is discussed. Our patient is the youngest in whom such an aneurysm has yet been reported. (Neurosurgery 28:623-625, 1991) Key words: Infected aneurysm, Staphylococcus aureus INTRODUCTION Intracranial aneurysms in early childhood are a rare clini- copathological entity. Three types of aneurysm may occur: saccular aneurysms (1, 7, 11, 13, 15, 19, 23), traumatic an- eurysms (19, 26), and infected aneurysms (3, 12, 15). In a review of the literature, Bohmfalk et al. (3) found only six cases of infected aneurysm in children aged 5 years or less since 1954. None of these patients was neonatal. In this paper, the occurrence of a ruptured, infected intra- cranial aneurysm ina |-month-old child is described. We have reviewed the cases reported in the literature, and discuss their etiology, pathogenesis, and management. CASE REPORT The patient, a previously healthy, 34-day-old female infant, experienced mild upper respiratory tract symptoms compli- cated on the 5th day by an acute episode of screaming asso- ciated with pallor, sweating, and vomiting. At admission to the children’s hospital, she had a temperature of 38°C and was tachypneic. No source of infection was identified, and a chest x-ray disclosed nothing abnormal. The findings of examina- tions of her cardiovascular system and abdominal tract were also normal. There was no evidence of skin sepsis. Examina- tion of the central nervous system revealed tense fontanels and symmetrically flaccid muscle tone, with no focal neurological signs. A lumbar puncture revealed uniformly blood-stained cerebrospinal fluid. After an ultrasound scan, 4 ml of subdural blood was aspirated from the corner of the left fontanel. In view of the pyrexia, blood cultures were taken. These grew Staphy~- lococcus aureus, sensitive to flucloxacillin (floxacillin), therapy with which was duly commenced. Forty-eight hours. later the child developed focal seizures and was transferred to the Institute of Neurological Sciences in Glasgow. On arrival she was apyrexial, with spontaneous eye opening. Focal neurological signs were evident: she was having right hemifacial seizures, and had a flaccid right arm and leg. Phenobarbitone therapy was continued, and the seizures were controlled. The full blood count at this stage showed a white cell count of 27.4 x 10°/L (56% neutrophils). A computed tomographic scan revealed a large hematoma in the left sylvian fissure with slight extravasation of blood into the subdural space; there were also zones of low density in the left frontal and temporal lobes. The extracranial soft tissue swelling seen on the scan was caused by an infiltrated intravenous line, which had been commenced at the referring hospital. There was no evidence of cellulitis or infection at this site (Fig. 1). After coagulation had been determined to be normal, a carotid angiogram was performed by direct puncture. A large aneu- rysm (17 mm) arising from a small sylvian branch of the left middle cerebral artery was demonstrated (Fig. 2). A left parietal craniotomy was performed, and the intra- cranial hematoma was evacuated. A large, partly clotted, fri- able aneurysm was found on a small middle cerebral branch, and was excised. Histological and bacteriological examination of the specimen revealed acute inflammation and polymorphs in the vessel wall. Postoperatively the hemiparesis resolved. An echocardio- gram showed normal cardiac anatomy and blood flow. At 6 months after surgery the child remained well and free of sei- zures. The only abnormal neurological sign was the presence of probable hemianopia. The child’s developmental progress appeared to be normal. DISCUSSION Despite the frequency of septicemic illness in the neonate. infected intracranial aneurysms in this age group are extremely rare. In the past 30 years, reports of infected aneurysms in early childhood have been sporadic. Six reported cases of bacterial aneurysms complicating infective endocarditis in infants with congenital or rheumatic heart diseases make cardiac sources the most important numerically (2, 14. 15, 27). Other aneu- rysms developing secondary to a variety of infective foci have 624 WHITFIELD and BULLOCK FiG. 1. Computed tomographic scan demonstrating the large in- tracerebral hematoma in the Jeft sylvian region and associated cere- bromalacia reflecting cerebral ischemia. Fic. 2, Left internal carotid angiogram, lateral view, demonstrat- ing an aneurysm on a sylvian branch of the left middle cerebral artery. been reported. These include cases in two infants with men- ingitis (16, 26) and in one with osteomyelitis of the skull and meningitis complicating a scalp abscess with cellulitis (25), A child with an infected cavernous sinus syndrome developed a saccular aneurysm of the intracavernous carotid artery (4), and another infant who had a history of generalized pyoderma developed a fatal infected intracranial aneurysm (10). A more recent report describes a child with orbital cellulitis who de- veloped an infected intracranial aneurysm (27). Our case is unusual in that there have been no previous reports of an Neurosurgery, Vol. 28, No. 4 infected aneurysm caused by a septicemic illness that appar- ently was secondary to an infection of the upper respiratory tract. In adults, infective endocarditis (8, 9), septicemia in intravenous drug abusers (3, 20), and the cavernous sinus syndrome (22) are the major causes, although in many cases, no cause is ever found. The exact pathogenesis of infected intracranial aneurysms is unknown. Contiguous arteritis is presumably responsible in aneurysms complicating meningitis and infected cavernous sinus syndromes, In cases secondary to sepsis in regions where the venous drainage includes emissary vessels, local arteritis is also probably responsible. In infective endocarditis and other septicemic illnesses, however, infected emboli lodging within small vessels are causative. The canine experiments of Moli- nari et al. (18) showed that the initial inflammatory response occurred in the adventitial layer of the vessel wall after a septic embolus had lodged in the vessel lumen. He proposed that either the bacteria escaped through the vessel wall into the Virchow-Robin space to cause this adventitial inflammation, or that the emboli caused stasis and inflammation in the vasa vasorum, resulting in the adventitial inflammation, which pre- ceded the inflammatory changes in the intima and media. He also noted the rapidity of the entire process of embolization, arteritis, and hemorrhage or false aneurysm formation, which occurred within 48 hours (17). Most reports of infected aneurysms confirm their predilec- tion for the peripheral branches of major arteries (3, 14, 26). Peripherally situated congenital saccular aneurysms are more common in children than in adults (1, 5, 27). Therefore, in children, an aneurysm on the distal branch of a major vessel, as in our patient, does not always indicate an infection as the cause. Excision and histological examination are therefore de- sirable to ensure that a septic focus is not missed. The management of infected aneurysms may be difficult. Prompt surgical excision of single or multiple distal aneurysms is advisable whenever possible (3, 6, 27). Neurological deficit is unlikely because of the peripheral site of these aneurysms, and the risk of recurrent hemorrhage is high if excision is not performed (3, 7). The management of proximal aneurysms is more complex. In a review of 13 cases of proximal bacterial aneurysm, Frazee et al. (6) concluded that the high mortality (60%) of patients treated conservatively should lead the neurosurgeon carefully to consider surgery in each case. Other surgeons advise a con- servative approach to the initial management of proximal an- eurysms (3, 21). In 1965, Roach and Drake (21) reserved surgery for patients in whom antibiotic therapy had failed to eradicate the aneurysm, because delayed fibrosis in the aneu- rysm wall would then permit safer surgical occlusion or wall reinforcement. Recent improvements in surgical techniques, such as the use of the operating microscope, bypass grafts, and encircling aneurysm clips, may allow more of these difficult proximal, fusiform aneurysms to be reinforced, or excluded from the circulation (24). In our case, the intracerebral hematoma and its mass effects necessitated urgent surgical treatment. We believe that even in this young age group, angiography should be performed when a spontaneous intracerebral hematoma is found and coagu- lopathy has been excluded. When an infected aneurysm is found, management must be based upon the individual findings in each patient, but urgent surgical excision, high doses of systemic antibiotic therapy, and eradication of the primary source of infection offer the best prospects for a favorable outcome. Received for publication, July 13, 1990: accepted, final form, No- vember 20, 1990. April 1991 Reprint requests: Mr. R Bullock. Department of Neurosurgery. Institute of Neurological Sciences, Southern General Hospital. 1345 Govan Road. Glasgow G51 4TF, Scotland. REFERENCES 1. Becker DH, Silverberg GD. Nelson DH. Hanberry JW: Saccular aneurysm of infancy and early childhood. Neurosurgery 2:1-7. 1978. . Bell WE, Butler C: Cerebral mycotic aneurysms in children, Two case reports. Neurology 18:81-86, 1968. 3. Bohmfalk GL. Story JL, Wissinger JP. Brown JE Jr: Bacterial intracranial aneurysm. J Neurosurg 48:369-382, 1978. 4. 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Shearburn EW: Intracranial aneurysm in a four-week old infant: Diagnosis by angiography and successful operation. J Neurosurg 18:122-124, 1961. 12. McDonald CA, Korb M: Special article: Intracranial aneurysms. Arch Neurol Psychiatry 42:298-328. 1939. 13. McLellan NJ. Prasad R, Punt J: Spontaneous subhyaloid and retinal haemorrhages in an infant. Arch Dis Child 61:1130-1132, 1986. 14. MeNeel D, Evans RA, Ory EM: Angiography of cerebral mycotic aneurysms. Acta Radiol (Diagn) 9:407-412, 1969. 15. Matson DD: Intracranial aneurysms in childhood. J Neurosurg 23:578-583, 1965. 16. Mitchell N, Angrist A: Intracranial aneurysms: A report of thirty- six cases. Ann Intern Med 19:909-923. 1943. 17. Molinari GF: Septic cerebral embolism, Stroke 3:117-122, 1972. 18. Molinari GF. Smith L. Goldstein MN, Satran R: Pathogenesis of cerebral mycotic aneurysms. Neurology 23:325-332. 1973. wv INFECTED INTRACRANIAL ANEURYSM 625 19, Newcomb AL. Munns GF: Rupture of aneurysm of the Circle of Willis in the newborn, Pediatrics 3:769-772. 1949. 20, Patel YD. Norowitz DB: Ruptured mycotic aneurysms. Cardio- vase Intervent Radiol 11:86-90. 1988. 21. Roach MR. Drake CF: Ruptured cerebral aneurysms caused by micro-organisms. N Engl J Med 273:240-244. 1965. 22. Shibuya S. Igarashi S, Amo T. Sata H, Fukumistu T: Mycotic aneurysms of the internal carotid artery. A case report. J Neuro- surg 44:105-108. 1976. 23. Storrs BB, Humphreys RP. Hendrick EB, Hoffman HJ: Intra- cranial aneurysms in the pediatric age-group. Childs Brain 9:358-361, 1982. 24. Sundt TM. Nofzinger JD: Clip grafts for aneurysm and small vessel surgery. Part B, Clinical experience in intracranial internal carotid artery aneurysm. J Neurosurg 31:59-71, 1969. 25. Suwanwela C, Suwanwela N, Charuchinda S, Hongsaprabhas C: Intracranial mycotic aneurysms of extravascular origin. J Neu- rosurg 36: 26. Thomson JR. Harwood Nash DC, Fitz CR: Cerebral aneurysms in children. Am J Roentgenol Radium Ther Nucl Med 118:163-175, 1973. 27. Zee CR. Feldman R: Intracranial arterial aneurysms in childhood: More recent considerations. J Child Neurol 1:99-114, 1986. COMMENT This is a case report concerning a child who was 34 days of age. The child had a sudden ictus associated with a focal seizure. Staphylococcus aureus was recovered from the blood stream, and a computed tomographic scan showed a large hematoma in the sylvian fissure. An angiogram revealed a 17-mm aneurysm arising from a branch of the middle cerebral artery. A craniotomy was performed, and the infected aneu- rysm was removed with the clot. Other reports of cases of aneurysm in children are reviewed. The authors rightfully point out the rarity of aneurysms in children in general and the occasional occurrence of mycotic aneurysms in children, Our experience has been that we see more posttraumatic and my- cotic aneurysms in the very young child than we do the typical congenital variety. I believe that this article is important not because it adds new findings to the Jiterature, but because it adds a case of an aneurysm in a very young child. It is also appropriate periodically to point out that aneurysms do oc- casionally occur in the very young child. David G. McLone Chicago, Illinois