Neurology India, Vol. 59, No. 5, September-October, 2011, pp. 753-755
Iatrogenic false aneurysm caused by surgery of a traumatic intracranial false aneurysm
Xiang Wang1, Jin-Xiu Chen2, Chao You1
1 Department of Neurosurgery, West China Hospital, Sichuan University, China
Keywords: False aneurysm, iatrogenic aneurysm, internal carotid artery, superficial temporal artery, traumatic aneurysm
Traumatic intracranial false aneurysms are rare and account for less than 1% of all cerebral aneurysms.  False aneurysms of the superficial temporal artery (STA) are uncommon and account for less than 1% of all traumatic aneurysms.  In this report, we describe a traumatic intracranial false aneurysm using consecutive computed tomography (CT) scans. In the postoperative period, he also developed a new false STA aneurysm at the first craniotomy site. Some features of a false aneurysm including its time of occurrence from initial trauma to aneurysm formation are analyzed.
A 28-year-old man who had a history of closed head injury presented with headache and periorbital ecchymosis (raccoon eyes). Immediate CT of head revealed anterior skull base fractures and traumatic subarachnoid hemorrhage [Figure - 1]a. Repeat CT scans performed on Day 7 [Figure - 1]b and on Day 16 [Figure - 1]c of the head injury showed a gradually evolving lesion near the right cerebral peduncle. Digital subtraction angiography (DSA) performed on Day 20 of the head injury revealed a 15.7 × 9.5 mm aneurysm on the supraclinoid segment of the right internal cerebral artery (ICA) and no other aneurysms were detected on both internal and external carotid arteries [Figure - 1]d.
The aneurysm was surgically approached through a right pterion craniotomy, it was a mass of blood blot or organized clot with arterial pulsation, arising from the bifurcation of the ICA and posterior communicating artery near the skull base, and grew downwards [Figure - 2]a. No obvious connective tissue was found on the neck of the aneurysm connecting the aneurysm with the parent artery. This false aneurysm avulsed from the parent artery, leaving a crevasse on the parental artery. After quick temporary clamping of both the sides of parent artery, a mini-clip was applied to clamp the crevasse in the parallel direction of blood flow in the ICA and reconstruction of the parent artery was done [Figure - 2]b. Temporary clips were removed and blood flow in the parent artery was monitored in the perioperative period by Doppler and the clip was adjusted. Subsequently, the remnant and parent arteries were wrapped with a thin layer of muslin gauze followed by circumferential application of gelatin sponge [Figure - 2]c.
Patient had a good postoperative recovery. Pathologic examination of the aneurysm revealed recent blood clots and a little fibrous tissue, without elastic or smooth muscle tissue [Figure - 2]d. On postoperative Day 25, repeat DSA showed a new aneurysm arising from the right STA, which was not apparent in the preoperative DSA, [Figure - 3]. This aneurysm was probably caused by iatrogenic injury to the STA during initial surgery as its location was close to the initial surgical incision [Figure - 3].
With the patient's consent, another operation was performed. Under local anesthesia, the proximal and distal parts of the STA were ligated and the aneurysm was resected through the same scalp incision. Histology confirmed a false aneurysm of STA. The patient recovered eventually.
This report describes the genesis of two rare false aneurysms in the same patient, one from traumatic head injury and the other due to iatrogenic injury. It is difficult to make the exact diagnosis of these aneurysms. However, certain specific features suggestive of a traumatic and "false" origin in this patient were history of head trauma with skull base fracture, evolving aneurysm as demonstrated by serial CT scans, dorsal wall aneurysm location, blister-like shape, and absence of a discrete neck. The most common location of intracranial traumatic false aneurysms is supraclinoid carotid artery, about 27%.  It is postulated that either movement of the supraclinoid segment against the anterior clinoid process or puncture by fractured skull base in this location results in aneurysm formation.
Cases of false aneurysms secondary to iatrogenic trauma have been described: cavernous segment false aneurysm following per nasal endoscope therapy; and pericallosal aneurysms following transcallosal surgery and ventricular catheterization. , The reported time interval from the initial trauma to aneurysm hemorrhage ranged from few hours to 10 years with an average of 21 days. , And the time interval between trauma and aneurysm formation is shorter. In our patient, both the aneurysms were identified in less than 25 days after injury.
The surgical excision of STA aneurysm is effective and not difficult. But surgery of intracranial false aneurysms is difficult and with a high morbidity. Without a real neck and sac wall, the dissection and preparation of the aneurismal sac for clipping involves an extremely high risk of perioperative rupture. Clip reconstruction and wrapping mentioned in this paper is a novel alternative to treat false aneurysm avulsion or a tear at aneurysm neck. This technique is useful to preserve the parent artery to deal with this urgent situation in the operation. 
Studying the evolution of aneurysm formation will help to identify aneurysmal features, such as a real aneurysm or false aneurysm, and help in determining the surgical risks before operation. Moreover, some of the iatrogenic factors that may predispose to aneurysm formation can be avoided.
Copyright 2011 - Neurology India
The following images related to this document are available:
Photo images[ni11224f3.jpg] [ni11224f2.jpg] [ni11224f1.jpg]