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Despite the widespread use of the pterional approach in neurosurgical procedures, complications due to iatrogenic injuries of the superficial temporal artery (STA) are extremely rare. Iatrogenic pseudoaneurysms of the STA have been reported as a complication of craniotomy,1 secondary to placement of external ventricular drainage catheters2 or of a pin type headholder device.3 Reported cases of iatrogenic arteriovenous fistula of the STA have occurred after hair transplantation4 and after temporomandibular arthroscopy.5 We report a case of iatrogenic arteriovenous fistula of the STA after pterional craniotomy. To the best of our knowledge, such a complication of craniotomy has not been reported before.
A 53 year old man was initially referred to our department with a grade 3 WFNS (World Federation of Neurological Surgeons) subarachnoid haemorrhage. Cerebral angiography revealed an anterior communicating artery aneurysm. A right pterional craniotomy was performed to clip the aneurysm. The superficial temporal artery was incised through a skin incision 7 cm above the tragus, and was coagulated carefully. The surgical procedure and postoperative course were uneventful, and the patient was discharged after two weeks with mild cognitive disturbances. Two months later, he complained of pulsatile tinnitus in the right ear. The tinnitus was exacerbated by lying on the right side. On physical examination, a thrill was palpable and a continuous murmur with systolic accentuation was audible on the pterional scalp incision above the tragus. The murmur and the thrill were abolished by compression of the proximal superficial temporal artery. Selective right external carotid artery angiography revealed an arteriovenous fistula between the main branch of the right STA and the homologous vein (fig 1). An internal carotid artery angiography was also performed, mainly to control the aneurysm, which showed no evidence of any contribution from the intracranial circulation. At operation, the arteriovenous fistula was proximally and distally ligated and excised completely. Postoperatively, the tinnitus disappeared, and the patient was discharged three days later. Six months after surgery there was no sign of recurrence.
Arteriovenous fistulas of the STA are rare lesions that occur most often after trauma or apparently spontaneously. The latent period between STA injury and the presentation of symptoms ranges from some days to 15 years. The presenting symptom usually includes a pulsatile, painless, expanding mass in the temporal region. The lesion may be accompanied by headache, pulsatile tinnitus, or dizziness. On physical examination, a palpable thrill and/or an audible continuous murmur may be detected. The murmur usually disappears or diminishes with proximal STA compression. In our case, the diagnosis of arteriovenous fistula of the STA was clinically obvious. However, an angiography of the external carotid artery was useful for surgical planning and demonstration of the feeding and draining vessels. The treatment of arteriovenous fistula of the STA is ligation and surgical excision, but successful endovascular embolisation of the fistula has also been reported.5 The latter treatment seems recommendable, because it is less aggressive and can be performed at the same time as angiography.
In fashioning the scalp flap for the pterional craniotomy, an injury to the STA is almost inevitable. Care must be taken in coagulation, or it might be preferable to ligate the incised stump. We suppose that, in our case, partial injury to the wall of the STA and the adjacent venous structures during suturing the wound, especially around tragus where the STA lies just beneath the skin incision, may have caused of the development of the fistula. We propose that arteriovenous fistula of the STA should be added to the list of possible complications following a pterional approach.