J Neurosurg 76: 134-136, 1992

Iatrogenic arteriovenous fistula presenting as a recurrent subdural hematoma Case report CONRAD ANDREW



Division of Neurological Surgery. Barrow Neurological Institute, Phoenix, Arizona

v An unusual case of an iatrogenic dural arteriovenous fistula is reported. The patient presented with a history of progressive generalized headache over a period of 3 to 4 weeks. Computerized tomography demonstrated a chronic subdural hematoma that was successfully evacuated by burr-hole drainage. The patient's postoperative course was complicated by recurrent acute subdural hematomas at the drainage site. Coagulation studies were unremarkable. Selective external carotid angiography demonstrated a small dural arteriovenous fistula adjacent to the burr hole used for the initial operative procedure. Extension of the bone flap and coagulation of the fistula resulted in a good outcome. In the patient with recurrent acute subdural hematoma, the possibility of a vascular malformation must be considered. Selective internal and external carotid angiography is key to the correct diagnosis. KEY WORDS • acute subdural hematoma • chronic subdural hematoma dural arteriovenous fistula • iatrogenic arteriovenous fistula


arteriovenous (A V) fistulae are relatively uncommon. They may occur spontaneously or as a result of trauma. Injury to the dural vessels associated with skull fractures or penetrating head trauma, particularly in the region crossing the meningeal grooves, has been described as a cause of traumatic AV fistula. 8.1 W The fistula itself does not usually cause symptoms over and above those that result from the head trauma. Thus, they have represented more of an angiographic curiosity than a threat to the well-being of the patient. We present an unusual case of an iatrogenic dural AV fistula that mimicked a recurrent acute subdural hematoma. The AV fistula resulted from injury to the meningeal vessels during burr-hole drainage of a chronic subdural hematoma. URAL

Case Report This 58-year-old woman experienced the gradual onset of generalized headache over a period of 3 to 4 weeks. The headaches became progressively more severe, and the patient sought medical evaluation from her family physician. A computerized tomography (CT) 134

scan was obtained, and she was referred to the Barrow Neurological Institute for further evaluation and treatment. Examination. The patient's medical history was negative for significant headaches or previous head trauma. Review of systems was remarkable only as indicated above, and general physical and neurological examinations were within normal limits. Review of the CT scan with contrast enhancement demonstrated a left convexity chronic subdural hematoma (Fig. I left). The subdural hematoma measured approximately 2 cm thick with a blood-fluid interface. Operations. The patient underwent burr-hole drainage of the chronic subdural hematoma. Surgery was performed without complications, and she awoke without change in neurological status. A follow-up CT scan on the 1st day postoperatively revealed no evidence of residual subdural hematoma. The patient did well until the 9th day postoperatively when she was noted to be aphasic and mildly right hemiparetic. A CT scan demonstrated a large acute left convexity subdural hematoma at the operative site (Fig. I right). The patient then underwent left frontoparietal craniotomy and unJ Neurosurg./ Volume 76/ January. 1992

Arteriovenous fistula mimicking subdural hematoma

FIG. I. Left: Axial contr~st enhancement

computerized tomography scan with at first presentation showing a left chrome subdural hematoma. Right: Noncontrast-enhanced computed tomography scan obtained after the first operation demonstrating an acute left subdural hematoma.

complicated evacuation of the acute subdural hematoma. Intraoperative inspection revealed no active bleeding sites or abnormal vasculature. The patient did well postoperatively for 24 hours, then suddenly deteriorated. Another CT scan demonstrated a recurrent acute subdural hematoma at the operative site. She was again returned to surgery and the hematoma was evacuated. A careful search of the operative field revealed no evidence of active bleeding or vascular abnormality. Clotting studies, evaluating plasma thromboplastin, partial thromboplastin time, platelet count, factor VIII, fibrinogen, and fibrin-split products, were all normal. Angiography was performed to rule out an occult vascular malformation. Selective external carotid artery injections demonstrated a small dural arteriovenous malformation (A VM) just anterior to the border of the original burr hole (Fig. 2). The AVM was fed by an enlarged branch of the anterior men~ngeal artery, with venous drainage paralleling the artenal supply. There was no evidence of arterial supply or venous drainage involving leptomeningeal branches. The patient then underwent another craniotomy. The anterior margin of the bone flap was extended to expose the dural AVM. The enlarged dural vessels were identified and coagulated, and the dura involved by the fistula was resected. Postoperative Course. The patient, who had been comatose since evacuation of the second hematoma gradually improved. At discharge 22 days after resectio~ of the dural AVM, her only neurological deficit was a mild expressive aphasia. Discussion

Postoperative hematomas are not uncommon as a complication of chronic subdural hematoma evacuation, and should be expected in any patient who deteriorates or does not improve postoperatively. Cooper l noted that true reaccumulation of the hematoma is reported to occur in as many as 45% of cases in some J. Neurosurg. / Volume 76/ January, 1992


2. Selective external carotid angiogram depicting a dural arteriovenous fistula.

series and probably results from bleeding from the vascularized outer membrane. Nevertheless, recurrent hematoma formation should lead to a thorough search for other possible etiologies for postoperative hematoma, including unsuspected coagulopathies, vascular injury, and the possibility of a vascular malformation. In the present case, the recurrence of acute subdural hematoma led to angiographic evaluation to rule out an occult vascular lesion. Selective external carotid angiography demonstrated a dural AV fistula immediately adjacent to a cranial burr hole that crossed a meningeal groove. . Traum~ to the middle meningeal artery, particularly m the regIon of the grooves on the inner aspect of the skull, can lead to formation of a dural AV fistula. 2,3.6.8, 10-12,15 Skull fractures or penetrating injuries that cross the meningeal grooves are the most common cause of these lesions and have been reported in about 2% of head trauma cases. 4 Anatomical studies ha ve demonstrate~ that two, meningeal veins normally accompany the middle menmgeal artery and its major branches. 15 Interestingly, it is the veins, rather than the artery, that produce and largely occupy the meningeal grooves. 7 This anatomical relationship may explain the increased frequency of traumatic AV fistulae in this region and is responsible for the characteristic angiographic appearance of these lesions, described as "tram tracks."S.12.15 More rarely, trauma will produce a fistula between the middle meningeal artery and a diploic veinY3 The natural history of traumatic dural AV fistulae is not well known, but it would appear that most of these lesions pose no significant threat to the patient and likely undergo spontaneous thrombosis. 5•6 .1O,15 The few case reports describing symptomatic convexity AV fistulae caused by trauma have noted headache, ophthal135

C. T. E. Pappas, J. M. Zabramski, and A. G. Shetter mological complaints, and bruits developing a month to a year after traumay,ll Descriptions of iatrogenic dural AV fistulae are rare in the literature. We found only three previously reported cases in which the fistula appeared to be directly related to the site of surgery. In two cases, delayed dural AV fistulae were documented at the operative site in patients undergoing suboccipital craniotomy.9 In the third patient, the lesion involved the base of the skull and followed elective clipping of an internal carotid artery aneurysm. 14 In all three cases, the patients presented with the delayed onset of pulsatile tinnitus. There was no history of perioperative bleeding complications, as in the case reported here. The present case of an iatrogenic dural AV fistula is representative of an uncommon lesion made even more unique by its symptomatic presentation. The key to successful diagnosis and treatment is a high index of suspicion. Recurrent postoperative hemorrhage should suggest the possibility of an occult vascular lesion. Angiography is the definitive test in such patients, and both internal and external carotid injections are essential for diagnosis. References 1. Cooper PR: Traumatic intracranial hematomas, in Wilkins RH, Rengachary SS (eds): Neurosurgery. New York: McGraw·Hill, 1985, Vol 2, pp 1657-1665 2. Feldman RA, Hieshima G, Giannotta SL, et al: Traumatic dural arteriovenous fistula supplied by scalp, meningeal, and cortical arteries: case report. Neurosurgery 6: 670-674, 1980 3. Fincher EF: Arteriovenous fistula between the middle meningeal artery and the greater petrosal sinus. Case report. Ann Surg 133:886-888,1951 4. Giannotta SL, Ahmadi J: Vascular lesions with head in-


5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

jury, in Wilkins RH, Rengachary SS (eds): Neurosurgery. New York: McGraw-Hili, 1985, Vol 2, pp 1678-1687 Ishii R, Ueki K, Ito J: Traumatic fistula between a lacerated middle meningeal artery and a diploic vein. Case report. J Neurosurg 44:241-244, 1976 Jackson DC, du Boulay GH: Traumatic arterio-venous aneurysm of the middle meningeal artery. Dr J Radiol 37:788-789, 1964 Jones FW: On the grooves upon the ossa parietalia commonly said to be caused by the arteria meningea media. J Anat PhysioI46:228-238, 1912 Leslie EV, Smith BH, Zol1 JG: Value of angiography in head trauma. Radiology 78:930-940, 1962 Nabors MW, Azzam CJ, Albanna FJ, et al: Delayed postoperative dural arteriovenous malformations. Report of two cases. J Neurosurg 66:768-772, 1987 Olutola PS, Eliam M, Molot M, et al: Spontaneous regression of a dural arteriovenous malformation. Neurosurgery 12:687-690, 1983 Pakarinen S: Arteriovenous fistula between the middle meningeal artery and the sphenoparietal sinus. A case report. J Neurosurg 23:438-439, 1965 Rumbaugh CL, Bergeron RT, Kurze T: Intracranial vascular damage associated with skull fractures. Radiographic aspects. Radiology 104:81-87, 1972 Saba MI, King RB: Extravasation of angiographic contrast material from a torn middle meningeal artery into the diploi. Case report. J Neurosurg 38:89-91, 1973 Watanabe A, Takahara Y, Ibuchi Y, et al: Two cases of dural arteriovenous malformation occurring after intracranial surgery. Neuroradiology 26:375-380, 1984 Wilson CB, Cronic F: Traumatic arteriovenous fistulas involving middle meningeal vessels. JAM A 188: 953-957, 1964

Manuscript received May 6, 1991.

Address reprint requests to: Joseph M. Zabramski, M.D.,

Editorial Office, Barrow Neurological Institute, 350 West Thomas Road, Phoenix, Arizona 85013.

J. Neurosurg. / Volume 76/ January, 1992

Iatrogenic arteriovenous fistula presenting as a recurrent subdural hematoma. Case report.

An unusual case of an iatrogenic dural arteriovenous fistula is reported. The patient presented with a history of progressive generalized headache ove...
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