NMC Case Report Journal
Online ISSN : 2188-4226
ISSN-L : 2188-4226
CASE REPORT
Coil Embolization of a Ruptured Traumatic Pseudoaneurysm of the Middle Meningeal Artery: A Case Report
Naoki NISHIZAWA, Tomoki KIDANI, Shin NAKAJIMA, Yonehiro KANEMURA, Katsunori ASAI, Nobuyuki IZUTSU, Saki KAWAMOTO, Koji KOBAYASHI, Mikako NOMOTO, Yosuke FUJIMI, Masayoshi KIDA, Toshiyuki FUJINAKA
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Keywords: traumatic pseudoaneurysm, middle meningeal artery, coil embolization, intracerebral hemorrhage
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2024 Volume 11 Pages 257-262

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Abstract

Traumatic pseudoaneurysms of the middle meningeal artery (MMA) are rare and have a poor prognosis due to their high risk of rupture. This study presents a case of a 53-year-old man who experienced rupture of an MMA pseudoaneurysm 10 days after craniotomy for an acute subdural hematoma caused by a blunt head injury. He also had an accompanying temporal bone fracture extending to the skull base. Initial imaging showed no evidence of cerebrovascular injury. The rupture resulted in a temporal hemorrhage with intraventricular extension that caused acute hydrocephalus. Digital subtraction angiography showed that the pseudoaneurysm was located just below the right temporal bone fracture. Coil embolization of the aneurysm was performed and complete occlusion was achieved. His hydrocephalus was addressed with placement of an external ventricular drain, which was later converted to a ventriculoperitoneal shunt. There was no rebleeding and he was transferred to a convalescent hospital. Traumatic MMA pseudoaneurysms usually develop several days after injury and are thus not present on imaging immediately after injury. Aggressive treatment is warranted due to their poor prognosis.

Introduction

The estimated incidence of middle meningeal artery (MMA) pseudoaneurysm after blunt head trauma is less than 1.0%.1) The prognosis of MMA pseudoaneurysm is poor: More than 80% will rupture2) and the mortality rate of rupture is 50%.1) We report a patient who experienced rupture of an MMA pseudoaneurysm 10 days after craniotomy for an acute subdural hematoma caused by a blunt head injury. The rupture resulted in a temporal hemorrhage with intraventricular extension that caused acute hydrocephalus. He was successfully treated with emergency coil embolization of the pseudoaneurysm and placement of an external ventricular drain.

Case Report

A 53-year-old man presented to our hospital after sustaining a head injury from a floor collapse. His Glasgow Coma Scale (GCS) score was 14 on arrival. Multiple head contusions were observed. Head computed tomography (CT) showed an acute right subdural hematoma with midline shift and a right temporal bone fracture extending to the skull base. Three-dimensional CT angiography (CTA) showed no obvious cerebrovascular injury (Fig. 1). He was immediately taken to the operating room for hematoma evacuation, decompressive craniotomy, and placement of an intracranial pressure monitor.

Fig. 1

(A, B) CT on admission showed an acute subdural hematoma with midline shift and fractures of the temporal and parietal bones (red arrowheads). (C) Three-dimensional CT angiography showed no obvious injury to the right MMA (red arrow).

After surgery, he remained intubated and was managed with sedation. The intracranial pressure monitor failed on postoperative day 3 and was removed. Postoperative head CT scans performed in the first 6 days showed a right posterior cerebral artery infarction but no rebleeding (Fig. 2A, B, C). His GCS score was 6T. On postoperative day 10, the his blood pressure increased and swelling under the craniotomy site was observed. Head CT showed a right temporal hemorrhage with extension into the ventricles and acute hydrocephalus (Fig. 2D, E, F).

Fig. 2

CT immediately after surgery (A) and on days 3 (B) and 6 (C) showed a right posterior cerebral infarction but no obvious intracerebral hemorrhage. (D, E, F) Ten days after surgery, imaging showed a right temporal hemorrhage with intraventricular extension and acute hydrocephalus.

Digital subtraction angiography (DSA) showed an irregular pseudoaneurysm of the right MMA. The dome and neck diameters were 9 mm and 4.7 mm, respectively. Contrast was actively extravasating into the hematoma cavity. The pseudoaneurysm was located just below the right temporal bone fracture near the foramen spinosum at the skull base (Fig. 3), an area not visualized during the patient's craniotomy. Coil embolization was immediately performed. A 6-Fr sheath was placed in the right femoral artery and a straight, 90 cm, 6-Fr Fubuki guiding catheter (Asahi Intecc, Aichi, Japan) advanced into the right external carotid artery. After guiding a 45° Excelsior SL-10 microcatheter (Stryker, Kalamazoo, MI, USA) into the pseudoaneurysm, we used four Target 360 XL Soft detachable coils (Stryker) to embolize it and the MMA (Fig. 4A, B, C). Postembolization angiography showed no contrast in the pseudoaneurysm or MMA distal to the embolization site.

Fig. 3

(A, B) DSA showed a pseudoaneurysm of the MMA with extravasation into the hematoma cavity. (C, D) The pseudoaneurysm was located along the temporal bone fracture line (red arrowheads) and was 9 mm and 4.7 mm in diameter.

Fig. 4

(A, B, C) The MMA pseudoaneurysm was completely embolized with four coils. (D) CT immediately after embolization showed contrast (red arrow) arising into the hematoma from the temporal skull base. (E) DSA on postoperative day 47 showed no recurrence of the pseudoaneurysm.

Head CT performed immediately after the procedure showed contrast accumulation within the temporal hematoma that appeared to arise from the skull base (Fig. 4D). External ventricular drainage was immediately performed to address the acute hydrocephalus. Sedation and blood pressure management were continued. Followup head CT showed no evidence of rebleeding. Cranioplasty was performed on postoperative day 33 and a ventriculoperitoneal shunt on postoperative day 42. Followup DSA on postoperative day 47 confirmed no pseudoaneurysm recurrence (Fig. 4E).

Discussion

Epidemiology of traumatic MMA pseudoaneurysm

The incidence of MMA pseudoaneurysm after blunt head trauma is estimated to be less than 1%.1) Traumatic MMA pseudoaneurysms have been reported to account for 27% of all traumatic intracranial aneurysms.1) The time from head injury to pseudoaneurysm formation ranges from 4 to 30 days.3) More than 80% of traumatic pseudoaneurysms rupture within 30 days, usually presenting with acute epidural hematoma.2) Although subdural, intracerebral, and subarachnoid hemorrhages have also been reported, these are rare.2,4-8) Some mechanisms for the development of ICH from a MMA pseudoaneurysm have been suggested. The dura mater has three distinct layers: outer, middle, and inner. Most cases of MMA pseudoaneurysms are located on the outer surface of the dura mater. This is because EDHs from MMA pseudoaneurysms are the most prevalent presenting type.9) Markwalder et al. proposed that meningeal aneurysms attaching to the inner dural surface and the cerebral cortex are the consequences of traction on a small vessel bridging the meningeal and cerebral vascular systems.10) It has also been suggested that in cases of ICH, the continuous pressure of the pseudoaneurysm slowly thins the dura mater until it attaches to the inner layer and consequently results in ICH.8,11) Pseudoaneurysm adhesion to the brain cortex might lead to the development of ICH.9) In our patient, a ruptured pseudoaneurysm was identified on day 10 despite a CTA showing no evidence of vascular injury on admission. His case is extremely unusual wherein pseudoaneurysm rupture resulted in intracerebral hemorrhage. The reported mortality of MMA pseudoaneurysm rupture is 50%.1) Our patient most likely survived due to early and accurate diagnosis and treatment.

Pathogenesis and anatomy

Traumatic MMA pseudoaneurysms occur when there is a tear through the vessel wall where a blood clot forms, which subsequently converts to fibrous tissue. This fibrous tissue of a pseudoaneurysm is more fragile than that of a true aneurysm wall; therefore, the risk of growth and/or rupture is greater with pseudoaneurysms.12) Typical features of a pseudoaneurysm on DSA are irregular aneurysmal sac without a neck, peripheral location distant from a branching point, and slow delayed contrast filling to the extent that it may only be visible in the late injection phase.2,12) Many of these characteristics were observed in our patient-the pseudoaneurysm was irregularly shaped and the contrast filling within was slow.

Risk factors for MMA pseudoaneurysms

MMA pseudoaneurysms are associated with ipsilateral temporal bone fractures in 70% to 92% of cases3,5,12,13) and approximately 85% are located in the temporal region.1,14) Pseudoaneurysms occur when a skull fracture in the temporal region causes a small tear in the arterial wall and the tear is sealed off by a clot.7,12,15) Our patient also had an ipsilateral temporal bone fracture and a pseudoaneurysm was identified along the fracture line. Kidani et al. reported that temporal/parietal bone fracture (P = 0.0005) was significantly associated with MMA-related vascular diseases.14) In head trauma cases with temporal bone fractures, it may be worth considering 3DCTA and DSA after day 4 of injury, when MMA pseudoaneurysms might develop.

Diagnosis

MMA pseudoaneurysms are diagnosed using CT, CTA, magnetic resonance angiography, and/or DSA.16) On CT, strong and homogenous enhancement of a hypodense nodule within an organized and encapsulated hematoma may indicate a MMA pseudoaneurysm.16) Both CTA and DSA have similar accuracy in detecting small intracranial cerebral aneurysms.12) However, CTA has a lower sensitivity.17) Therefore, DSA is considered the gold standard imaging modality for diagnosing traumatic pseudoaneurysm.16) Since they develop in a delayed fashion, traumatic pseudoaneurysms may not be found on imaging studies performed immediately after injury.3,14) In our patient, CTA performed immediately after the injury did not identify a MMA pseudoaneurysm.

Management

Management options for traumatic MMA pseudoaneurysms are craniotomy, resection, endovascular embolization, and observation.7) Some may even heal spontaneously without treatment.12) Shah et al. reported an incidental traumatic MMA pseudoaneurysm that resolved spontaneously after 1 month of observation.18) Srinivasan et al. reported complete resolution of a traumatic MMA pseudoaneurysm and decrease in size of the associated epidural hematoma after 2 weeks of observation.19) If surgical treatment is elected, the pseudoaneurysm may be excised, clipped, or trapped and the surrounding hematoma may also be evacuated at the same time. However, due to the friable nature of the aneurysm, which frequently lacks a satisfactory aneurysmal neck for clip placement, surgery can be challenging. Furthermore, the risk of intraoperative rupture and other surgical complications is higher with pseudoaneurysm surgery than with surgery for common saccular aneurysms.16) During open surgery for ruptured MMA pseudoaneurysms, active bleeding from the base of middle cranial fossa can be difficult to control, resulting in hemorrhagic shock. In such cases, intraoperative angiography and embolization using n-butyl cyanoacrylate can be helpful.20) In our patient, we believed that open surgery would be unable to address bleeding arising from the basilar side of the skull and not enable identification of the source.

Marvin et al. advocated endovascular embolization to eliminate hemorrhage risk in MMA pseudoaneurysm patients in whom surgical decompression is not considered mandatory.8) Several case reports have demonstrated the safety and efficacy of coil embolization for traumatic MMA pseudoaneurysms.3,16,21) However, any manipulation of the pseudoaneurysm wall during the procedure, whether with the microcatheter or during coil placement, may result in rupture. In addition, the pseudoaneurysm may remain if only proximal occlusion is achieved.16,22) Use of tissue adhesives or hydrogels as the embolic agent rather than coils is another treatment option. Lu et al. reported successful embolization of an angiographically progressive traumatic MMA pseudoaneurysm using Onyx (Medtronic, Minneapolis, MN, USA).16) Moreover, Marvin et al. used Onyx and reported no recurrence on CTA 15 months later.8) Cuoco et al. embolized a traumatic pseudoaneurysm and arteriovenous fistula of the MMA using n-butyl cyanoacrylate and reported no recurrence on the 1-year followup CTA.22) Traumatic MMA pseudoaneurysms with the development of intracerebral hemorrhage have been treated by both craniotomy and endovascular therapy. Craniotomy involves resection of the aneurysm and dissection and coagulation of the MMA,2,4,6,10,23-28) while endovascular treatment involves embolization with liquid embolic material and coils. Most endovascular treatment involves embolization with liquid embolization material,5,8,27,29-31) and only two cases of embolization with coils alone have been reported so far.32) In our patient, the MMA pseudoaneurysm was located just distal to the foramen spinosum; therefore, use of tissue adhesives or hydrogels carried a risk of unintentional embolization of a facial nerve branch or a branch that anastomosed with the ophthalmic artery, which may have caused facial paralysis or loss of eyesight, respectively. Moreover, there was no contrast in the MMA distal to the pseudoaneurysm. As a result, we elected to perform coil embolization. Fortunately, it was effective and no recurrence was visualized on angiography 47 days after the procedure.

Conclusion

The prognosis of traumatic MMA pseudoaneurysm rupture is poor. Rapid diagnosis and aggressive treatment of these pseudoaneurysms are advisable. Endovascular embolization using coils or a liquid embolic agent is a treatment option.

Acknowledgments

We thank Edanz (https://jp.edanz.com/ac) for editing a draft of this manuscript.

Informed Consent

The consent was obtained from all the participants.

Conflicts of Interest Disclosure

The authors declare no conflicts of interest.

References
 
© 2024 The Japan Neurosurgical Society

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