A 76-year-old female presented with a large upper basilar artery (BA) aneurysm causing obstructive hydrocephalus after coil embolization manifesting as ...
CASE REPORT Neurol Med Chir (Tokyo) 52, 832¿834, 2012
Endoscopic Third Ventriculostomy for Obstructive Hydrocephalus Caused by a Large Upper Basilar Artery Aneurysm After Coil Embolization —Case Report— Masayuki SATO,1 Yasunobu NAKAI,1 Tomoji TAKIGAWA,1 Shingo TAKANO,1 and Akira MATSUMURA1 1Department
of Neurosurgery, Graduate School of Comprehensive Human Science, University of Tsukuba, Tsukuba, Ibaraki
Abstract A 76-year-old female presented with a large upper basilar artery (BA) aneurysm causing obstructive hydrocephalus after coil embolization manifesting as diplopia. Magnetic resonance (MR) imaging and MR angiography showed a large BA top aneurysm. Coil embolization was performed. More than 6 months after the first coil embolization, the aneurysm had re-grown and we performed a second coil embolization. Soon after that, obstructive hydrocephalus at the aqueduct of the midbrain occurred. MR imaging was performed to evaluate whether there was enough space at the prepontine cistern for a third ventriculostomy and also to verify the posterior direction of the aneurysm growth because of the risk of rupturing the aneurysm during the operative procedure. Then, we performed an endoscopic third ventriculostomy (ETV) via a left-sided approach. We could easily identify the infundibular recess, mamillary bodies, and tuber cinereum in the third ventricular floor. We detected a pulsating upper BA aneurysm that appeared to have caused a reddish color change in the right mammillary body and the right side of the thalamus and midbrain. If there is sufficient space in the prepontine cistern for the surgical procedure, ETV is a good choice for the treatment of obstructive hydrocephalus associated with cerebral aneurysms. Key words: large upper basilar artery aneurysm, obstructive hydrocephalus, endoscopic third ventriculostomy, coil embolization, perianeurysmal edema
Introduction
Case Report
Upper basilar artery (BA) aneurysm associated with obstructive hydrocephalus is relatively rare,2,4,5,10,14,18,19) but is a critical situation due to obstruction of the cerebrospinal fluid (CSF) pathway requiring emergency management. We usually utilize a ventriculo-peritoneal (VP) shunt for treating hydrocephalus, but several case reports have shown that this procedure carries a risk of inducing growth of the aneurysm.5,8) For these patients, endoscopic third ventriculostomy (ETV) is an ideal treatment to improve hydrocephalus,13) but has some technical disadvantages if the aneurysm is located at the top of the BA.7,15,17) Here, we present a case of obstructive hydrocephalus due to a large upper BA aneurysm after coil embolization, successfully treated by ETV.
A 76-year-old female presented with diplopia, then underwent magnetic resonance (MR) imaging and MR angiography, which indicated a large aneurysm of the upper BA. She visited our university hospital and underwent angiography which revealed an aneurysm with 17.8 × 14.0 mm diameter located in the upper BA. MR imaging showed the aneurysm compressing the right cerebral peduncle and located near the oculomotor nerve without intra-aneurysmal hematoma. We performed coil embolization with Matrix 2 coils (Target Therapeutics, Boston Scientific, Fremont, California, USA) (Fig. 1A, D). About 6 months after the first coil embolization, follow-up MR angiography showed coil compaction and also indicated neck growth of the aneurysm with a maximal diameter of 27 mm. The aneurysm was growing in the posterior direction in the prepontine cistern, and had compressed the right side of the thalamus and the midbrain more progressively than at the initial presentation. We performed a second coil embolization using the bare platinum Guglielmi Detachable Coil system (Target Therapeutics, Boston
Received 2011
November 17, 2011;
Accepted
December 28,
832
ETV for Hydrocephalus Caused by BA Aneurysm
Fig. 1 Angiograms of the left vertebral artery and axial T2weighted magnetic resonance images before treatment (A, D), immediately after the first coil embolization (B, E), and immediately after the second coil embolization (C, F).
Fig. 2 A: Sagittal heavily T2-weighted magnetic resonance (MR) image showing obstruction of the aqueduct of the midbrain by the embolized large aneurysm. B: Coronal fluid-attenuated inversion recovery (FLAIR) MR image showing perianeurysmal edema on the right side of the thalamus and midbrain, and obstructive hydrocephalus. C: Sagittal heavily T2weighted MR image after the third ventriculostomy showing flow jets at the third ventricular floor. D: Coronal FLAIR MR image after the third ventriculostomy showing improving perianeurysmal edema and hydrocephalus.
Scientific) with a balloon assist technique for tighter packing in the aneurysm (Fig. 1B, E). Immediately after the second coil embolization, MR imaging showed a large coiled mass compressing the midbrain and the aqueduct of the midbrain shifting to the left (Fig. 1C, F).
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Fig. 3 Intraoperative endoscopic view at the third ventricle floor clearly showing the landmark structures (arrowhead, infundibular recess; arrow, tuber cinereum; double arrow, mamillary bodies). This view shows the reddish color change in the right mamillary body, thalamus, and midbrain.
Two weeks after the second coil embolization, she showed drowsiness and memory disturbance. MR imaging revealed peri-aneurysmal edema on the right side of the thalamus and midbrain, as well as obstructive hydrocephalus caused by the coiled large aneurysm at the aqueduct of the midbrain (Fig. 2). Increased CSF flow was needed by the construction of an alternative flow pathway. Sagittal heavily T2-weighted MR imaging showed that the aneurysm location and growth direction were posterior, indicating adequate space in the prepontine cistern for safely performing a third ventriculostomy. Coronal heavily T2-weighted MR imaging showed that we could approach the third ventricle floor directly via the left lateral ventricle to the intraventricular foramen of Monro. We could detect landmark structures and perform the operation easily. We introduced an intraventricular videoscope (VEF type V; Olympus, Tokyo) through the left anterior horn to the third ventricle. We could easily identify the infundibular recess, mamillary bodies, and tuber cinereum in the third ventricular floor, and observed a pulsating upper BA aneurysm located near the right mamillary body with a reddish color change (Fig. 3). Taking care not to rupture the aneurysm, we perforated the third ventricle floor with a 4-Fr Fogarty balloon. Carefully and gradually inflating the balloon, we established a CSF pathway with sufficient flow by checking the to-and-fro movement of the floor. After inspecting the ventriculostomy, we observed an upper BA aneurysm and obstructed aqueduct of the midbrain. After the operation, her consciousness soon improved compared with before surgery. Two months later, her clinical status remained stable.
Discussion The present case of upper BA aneurysm causing obstructive hydrocephalus through coil embolization resulting in aneurysm growth was treated by ETV. Obstructive hydrocephalus at the aqueduct of the midbrain is a good indication for ETV, which has only a slight risk of surgical complication.15,16) However, hydrocephalus caused by a large or giant upper BA aneurysm carries more risk for
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surgery because of the location in the prepontine cistern, with consequent risk of rupture in the process of perforating the third ventricle floor. Three cases of unruptured upper BA aneurysm associated with obstructive hydrocephalus have been successfully treated.13) The selection of patients is most important for safe ETV. The key points are sufficient space in the prepontine cistern for the surgical procedure, and detection of normal structures such as the mamillary bodies and infundibular recess. We used sagittal heavily T2-weighted MR imaging to check the prepontine space and found aneurysm growth in the posterior direction. We also considered the approach direction using coronal heavily T2weighted MR imaging in relation to easily identifiable landmark structures and the right side of the ventricle wall. In this case, we could perform ETV safely and successfully through a left-sided approach. VP shunt for obstructive hydrocephalus caused by upper BA aneurysm can lead to aneurysm growth and increased risk of rupture,8) as the VP shunt rapidly reduces intracranial pressure and compromises the tamponade effect, which leads to expansion of the aneurysm. Therefore, if ETV can be performed on obstructive hydrocephalus, it is a good choice for obstructive hydrocephalus with cerebral aneurysms. Recent articles have reported various cases of hydrocephalus after coil embolization with either hydrogel-coated platinum coils or bare platinum coils, as well as for unknown reasons.1,11,12) In our case, the regrowth of the aneurysm became a space-occupying mass at the third ventricle, which caused obstructive hydrocephalus, and the peri-aneurysmal edema was worsening due to re-growth of the aneurysm. Incomplete occlusion of large aneurysms can lead to disorganized intraluminal thrombosis, aneurysm pulsing, and intramural hemorrhage or inflammation.6,9) We directly observed a pulsating upper BA aneurysm located near the right mamillary body with a reddish color change using the videoscope. We thought the reddish color change of the ventricle wall was a result of the aneurysm pulsation and coil compression causing inflammation.3) Complete tight packing of a residual aneurysm leads to reduction of the water hammer effect, which is one factor in peri-aneurysmal inflammation.9) Finally, after the third ventriculostomy and second coil embolization of the aneurysm, follow-up MR imaging showed improvement of the peri-aneurysmal edema, suggesting that the aneurysm pulsation was the main cause of the reddish color change of the mammillary body. In the present case, we observed the pulsating aneurysm after complete coil embolization by endoscopy directly, showing that we still risk causing new neurological worsening when treating large or giant aneurysm with coils.
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Address reprint requests to: Dr. Shingo Takano, Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, 1–1–1 Tennoudai, Tsukuba, Ibaraki 305–8575, Japan. e-mail: Shingo4＠md.tsukuba.ac.jp
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