J Neurosurg 77:624-627, 1992
Giant thrombosed vertebral artery aneurysm managed with extracranial-intracranial bypass surgery and aneurysmectomy Case report KENJI WAKUI, M.D., SHIGEAKI KOBAYASItl, M.D., TOSHIKI TAKEMAE, M.D., YUKIHIRO KAMIJOH, M.D., H1SASHI NAGASHIMA, M.D., AND SHINSUKE MURAOKA, M.D.
Department of Nettrosurgeo', Shinshu University School ~?fMedicine, Matsumoto, and Kobayashi Neurosurgical Hospital, Nagano, Japan ~" A case is presented of a left giant thrombosed vertebral artery aneurysm in a 46-year-old man. The giant thrombosed aneurysm was successfully resected with trapping of the affected artery after right external carotid artery-posterior cerebral artery bypass surgery using a radial arterial graft. The clinical course is reported, and the details of the operative approach and techniques are discussed. KEY WORDS
"
vertebral artery
N the literature T M ],13 and in our experience, dissecting aneurysms and atherosclerotic fusiform aneurysms of the vertebral artery (VA) are primarily unclippable, and proximal ligation or clipping of the VA is the most commonly used method of treatment. In the case of a giant aneurysm, the mass causes severe neurological deficits, and decompression by aneurysmectomy is necessary. When the affected VA is dominant, its proximal occlusion is not a safe procedure. We encountered a case of giant thrombosed aneurysm of the left VA which had caused severe progressive neurological deficits. Trapping of the affected VA and aneurysmectomy were performed immediately following right external carotid artery (ECA)-posterior cerebral artery (PCA) bypass surgery using a radial arterial graft. The details of the surgical approach and techniques used are reported.
I
Case Report This 46-year-old man first complained of headache in June, 1990. He visited one of our affiliated hospitals where computerized tomography (CT) revealed a large enhancing mass of 50 m m in maximum diameter with a calcified wall and a dilated vessel in the posterior fossa (Fig. 1). During the course of his illness, swallowing difficulties and gait disturbances gradually occurred. He 624
giant aneurysm
9 thrombosis
9 bypass procedure
was admitted to the hospital on September 4, 1990, for further examination and operation. Examination. The patient had marked truncal ataxia and dysphagia, but no motor or sensory deficits. Magnetic resonance (MR) imaging revealed the mass clearly displacing the medulla posteriorly, with a small flow-void area in the ventral side (Fig. 2). Vertebral angiograms showed a serpentine aneurysm of the left VA (Fig. 3). The right VA terminated solely in the posterior inferior cerebellar artery (PICA). There was no opacification of the PCA via the posterior communicating arteries (PCoA's). First Operation. A bypass surgical procedure was planned as the initial procedure because the basilar artery was supplied only by the left VA. On September 11, 1990, with the patient in the supine lateral position, a left temporal craniotomy was made. A saphenous vein graft was harvested from the left leg and interposed between the ECA and the left superior cerebellar artery, (SCA). The graft blood flow was 120 cu cm/min. Postoperatively, the patient's condition worsened, necessitating use of a respirator via tracheostomy for I month. The left carotid angiogram performed on the following day showed that the vein graft was occluded. In order to reduce blood flow to the aneurysm, the left VA was exposed in the neck under local anesthesia and
J. Neurosurg. / Volume 77/October, 1992
Giant thrombosed vertebral artery aneurysm
FIG. 1. Preoperative contrast-enhanced computerized tomography scans. Left: The giant aneurysm and the dilated proximal parent artery (arrow) are shown. Right: The giant thrombosed aneurysm measures 50 mm in maximum diameter with a calcified wall.
was ligated at its origin from the subclavian artery after test occlusion. However, the angiogram showed that the serpentine aneurysm and the basilar artery were still well opacified by the collateral flow from the left thyrocervical trunk. The patient was referred to the University Hospital for further therapy on December 14, 1990. During his illness, his orientation deteriorated and a ventriculoperitoneal shunt was inserted for treatment of hydrocephalus, but no remarkable improvement was obtained. The neurological findings on admission were: mild right facial palsy of the central type, bilateral hearing disturbance, dysphagia, mild hypesthesia involving the right side of the face, fight dominant disturbance of position sense, and ataxia of the trunk and extremities. The patient was bedridden.
Second Operation. On February 6, 1991, we performed a craniotomy using an approach essentially the same as that in the third operation (described below). This time, because of further progression of symptoms, a certain degree of decompression was deemed necessary. With the patient in the lateral deeubitus position, a large temporo-occipital skin incision shaped like a question mark and extending to the anterior edge of the right sternocleidomastoid muscle was made and a right temporosuboccipital craniotomy was carried out. A partial mastoidectomy was performed and the mastoid process was removed. The sigmoid sinus was unroofed to the jugular foramen, which was opened posteriorly. The craniectomy was carried inferiorly to the foramen magnum. An extreme lateral approach 7 was made with C-1 hemilaminectomy and by drilling the posterior half of the occipital condyle. In order to expose the left VA proximally, the right VA was mobilized by cutting the dura on both sides of its dural penetration. The distal left VA and basilar artery were visualized by retracting the sigmoid sinus posteriorly. Both the proximal and distal parent arteries were secured. The fifth to 12th cranial nerves had been stretched by the underlying giant aneurysm. The thinned medulla was partly seen overriding the aneurysm, and the ports was displaced cranial to the fifth J. Neurosurg. / Volume 77 / October, 1992
FJ(;. 2. Preoperative magnetic resonance images, axial view (l~ft) and sagittal view (right). The aneurysm is markedly displacing the medulla posteriorly. A flow-void area is recognized in the ventral side of the aneurysm.
FIG. 3. Preoperative left vertebral angiograms, anteroposterior projection (left) and lateral projection (right). The serpentine aneurysm is recognized. The vertebral artery is running from the left to the right upper side.
nerve. The aneurysm wall was cut about 1.5 cm between the seventh and 12th nerves. The content of the thrombosed aneurysm was removed carefully by the ultrasonic aspirator under the guidance of a Doppler flowmeter for determining the course of the VA inside the aneurysm. The portion of the aneurysm that bulged most against the medulla was decompressed to a depth of 2.5 cm. As oozing of blood started inside the aneurysm, debulking was stopped here. The lower medulla was considered to be well decompressed. The aneurysmotomy wound was closed by suture and reinforced with fabricated cotton and fibrin glue. The patient's consciousness disturbance was slightly better postoperatively but the symptoms did not improve much. A postoperative CT scan showed a partial thrombectomy of the aneurysm (Fig. 4). A radical aneurysmectomy for complete decompression was designed because of the additional progressive neurological deficits: left trochlear and accessory nerve palsy, fight hypoglossal nerve palsy, and left hemiparesis; however, this third operation was postponed due to recurrent pneumonia. Third Operation. On May 27, 1991, with the patient in the supine lateral position, the wound from the second operation was reopened and a radial artery bypass was performed from the fight neck ECA to the fight PCA (P2 segment); graft patency was confirmed 625
K. Wakui, el aL
FIG. 4. Computerized tomography scan after the second operation. The low-density area shows the region of partial thrombectomy.
FIc;. 6. Radiographic studies after the third operation.
Upper L{2[L Computerized tomography scan. Space created by the aneurysmeclomy showing a large low-density area. The remaining wall of the aneurysm is seen as a linear high-density area. Upper Right. Magnetic resonance image showing the medulla markedly decompressed. Lower: Right carotid angiograms, anteroposterior view (left) and lateral view (right). There is good patency of the radial arterial graft (arrows) and the basilar arterial system is well opacified.
FIG. 5. Schematic drawing of the third operative view. The aneurysm was trapped with clips and the content of the aneurysm removed. The wall of the aneuusm was resected. VA = vertebral artery; GRAFT = radial arterial graft; PCA = posterior cerebral arteu: BA = basilar artery.; V, VII, and VIII = trigeminal, facial, and acoustic nerves; AICA = anterior inferior cerebellar artery'.
intraoperatively with the Doppler flowmeter. The previous operative wound was densely adherent and it was extremely difficult to find and confirm the important structures. First, the fight VA and PICA were found; they had thrombosed and were black. Then, the contralateral left VA was found. The basilar artery was separated from the aneurysm and the fight anterior inferior cerebellar artery (AICA) was found and dissected free. The aneurysm was trapped with temporary clips placed on the left VA and basilar artery. The aneurysm was entered and the content of the aneurysm was removed, mostly by the ultrasonic aspirator. As we decompressed the aneurysm it became possible to further visualize the inlet and outlet ostia. The trapping clips were replaced closer to the aneurysm. During this process, both AICA's were found and spared from clipping, together with a couple of perforating arteries. These procedures were facilitated by cutting the aneurysm wall. Except for the dorsomedial wall of the aneurysm, which had 626
been attached to the medulla and was mostly calcified, the remaining aneurysm wall was thinned from the inside as much as possible, thus achieving complete decompression (Fig. 5). Patency of the radial arterial graft and the retrograde blood flow of the basilar artery were confirmed with the Doppler flowmeter.
Postoperative Course. The patient showed a gradual improvement of his preoperative deficits (truncal ataxia and left hemiparesis), but severe dysphagia persisted. A C T scan, MR image, and right carotid angiograms showed the posterior fossa well decompressed and good patency of the radial arterial graft through which the basilar arterial system was well opacified (Fig. 6). The patient could sit up in a chair and was discharged 3 months later for further rehabilitation. Left hemiparesis completely disappeared and right facial palsy, hearing disturbance, and dysphagia have gradually improved; he can swallow saliva. He still has truncal ataxia and is now exercising by standing on an inclining bed at our affiliated hospital. Discussion Surgery for giant intracranial aneurysms has three important purposes: reducing the mass effect causing severe neurological deficits; preventing rupture; 3'9 and preventing ischemic complications. 3,1z Direct surgical treatment of giant aneurysms of the VA includes proximal ligation, neck clipping, or aneurysmectomy. 9 The best way to treat an aneurysm is clipping the neck, but giant aneurysms in this location are difficult to clip because temporary trapping is often impossible in a
J. Neurosurg. / Volume 77 / October, 1992
Giant thrombosed vertebral artery aneurysm tight operating feld, especially with regard to securing the distal side of the parent artery; also the aneurysms are usually atherosclerotie, fusiform, or serpentine, with solid thrombosis. Yamaura ~3reported 94 VA aneurysms in 86 patients which were analyzed for their clinical manifestation, diagnosis, and treatment. These included 56 (60%) saccular aneurysms, 26 (28%) dissecting aneurysms, and 12 (13%) atherosclerotic fusiform aneurysms. Dissecting aneurysms and atherosclerotic fusiform aneurysms were primarily unclippable, and proximal clip-occlusion of the VA was the most c o m m o n surgical technique in that series. When the neurological deficits caused by the mass are minimal, even simple ligation of the proximal VA yields a satisfactory result without complications. 468~ If the contralateral VA and the PCoA are well developed, blood supply to the brain stem and cerebellum is sufficient even with the affected VA ligated. However, when the mass causes severe neurological deficits and the affected VA is dominant, bypass surgery L2'5'"; is necessary and decompression by aneurysmectomy or aneurysmotomy is demanded. In the present case, the left ECA-SCA anastomosis was performed as the first step before direct surgical attack on the giant thrombosed aneurysm of the left VA because the basilar artery was supplied only by the affected VA. The saphenous vein graft became occluded the next day, perhaps due to the low pressure gradient between the anastomoses. The decompression of the aneurysm by partial thrombectomy performed as a semi-emergency procedure for progressive symptoms was not satisfactory because we were afraid to enter the blood compartment inside the aneurysm while removing clots. However, surgical exposure of the aneurysm was excellent, with a combined right transmastoid, petrosal, suboccipital, condylar, extreme-lateral approach 7 utilizing pre- and retrosigmoid routes. The left VA and PICA were well opacified on the angiogram through the anastomoses via the muscular branches from the left thyrocervical trunk, even after the proximal ligation at the origin of the left VA. We wanted to avoid injury to the muscular branches in order to preserve the left PICA by approaching the aneurysm from the left side. We judged from the angiogram that the distal parent artery could be secured only from the fight side due to the abnormal course of the left VA (Fig. 3), and that the proximal parent artery could also be visualized and secured by this approach. Both proximal VA's could be secured at the beginning of the direct attack to the aneurysm by the extreme-lateral approach.7 This approach allowed a wide operative view of the aneurysm and facilitated securing both the proximal and distal parent arteries. Almost all the intraluminal clots were evacuated by the ultrasonic aspirator. The Doppler flowmeter is also useful for identifying the course of the blood compartment inside a thrombosed aneurysm or detecting the ostia to the parent artery. J. Neurosurg. / Volume 77 / October, 1992
In the third operation, the right ECA-PCA bypass surgery was performed in the same surgical field. The radial arterial graft may have remained patent in part because it may be a better graft material than the saphenous vein, ~4 and in part because the VA was occluded simultaneously. There were some small perforating vessels from the aneurysm wall but they might not be functionally important. In such cases of thrombosed giant VA aneurysm causing severe progressive neurological deficits where the affected VA is dominant, aneurysmectomy for decompression with trapping of the parent arteries after simultaneous bypass surgery via this combined approach appears to be a safe and satisfactory strategy. References
1. Ausman JI, Lee MC, Chater N, et al: Superficial temporal artery to superior cerebellar artery anastomosis for distal basilar artery stenosis. Surg Neural 12:277-282, 1979 2. Hopkins LN, Budney JL, Castellani D: Extracranial-intracranial arterial bypass and basilar artery ligation in the treatment of giant basilar artery aneurysms. Neurosurgery 13:189-194, 1983 3. Hosobuchi Y: Direct surgical treatment of giant intracranial aneurysms. J Neurosurg 51:743-756, 1979 4. Ishii R, Tanaka R, Koike T, et al: Computed tomographic demonstration of the effect of proximal parent artery ligation for giant intracranial aneurysms. Surg Neuroi 19: 532-540, 1983 5. Lansen TA, Kasoff SS, Arguelles JH: Giant pediatric aneurysm treated with ligation of the middle cerebral artery with the Drake tourniquet and extracranial-intracranial bypass. Nenrosurgery 25:81-85, 1989 6. Massey CE, El Gammal T, Brooks BS: Giant posterior inferior cerebellar artery aneurysm with dysphagia. Surg Neurol 22:467-471, 1984 7. Sen CN, Sekhar LN: An extreme lateral approach to intradural lesions of the cervical spine and foramen magnum. Neurosurgery 27:197-204, 1990 8. Sugita K: Microneurosurgical Atlas. Berlin: Springer-Verlag, 1985, pp 116-135 9. Sugita K, Kobayashi S, Toshiki T, el al: Giant aneurysms of the vertebral artery. Report of five cases. J Neurosurg 68:960-966, 1988 10. Sundt TM Jr, Piepgras DG: Occipital to posterior inferior cerebellar artery bypass surgery. J Nenrosurg 48:916-928, 1978 11. Waga S, Fujimoto K, Morooka Y: Dissecting aneurysm of the vertebral artery. Surg Neural 10:237-239, 1978 12. Whittle IR, Dorsch NW, Besser M: Spontaneous thrombosis in giant intracranial aneurysms. J Neurol Neurosurg Psychiatry 45:1040-1047, 1982 13. Yamaura A: Diagnosis and treatment of vertebral aneurysms. J Neurosarg 69:345-349, 1988 14. Yasui N, Ohta H, Suzuki A, et al: Cervical carotid artery to middle cerebral artery anastomosis with interposed radial artery graft, in Spetzler RF, Carter LP, Selman WR, et al (eds): Cerebral Revascularization for Stroke. New York: Thieme-Stratton, 1985, pp 379-385 Manuscript received November 25, 1991. Accepted in final form March 1I, 1992. Address reprint requests to: Kenji Wakui, M.D., Department of Neumsurgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390, Japan. 627
Giant thrombosed vertebral artery aneurysm managed with extracranial-intracranial bypass surgery and aneurysmectomy Case report KENJI WAKUI, M.D., SHIGEAKI KOBAYASItl, M.D., TOSHIKI TAKEMAE, M.D., YUKIHIRO KAMIJOH, M.D., H1SASHI NAGASHIMA, M.D., AND SHINSUKE MURAOKA, M.D.
Department of Nettrosurgeo', Shinshu University School ~?fMedicine, Matsumoto, and Kobayashi Neurosurgical Hospital, Nagano, Japan ~" A case is presented of a left giant thrombosed vertebral artery aneurysm in a 46-year-old man. The giant thrombosed aneurysm was successfully resected with trapping of the affected artery after right external carotid artery-posterior cerebral artery bypass surgery using a radial arterial graft. The clinical course is reported, and the details of the operative approach and techniques are discussed. KEY WORDS
"
vertebral artery
N the literature T M ],13 and in our experience, dissecting aneurysms and atherosclerotic fusiform aneurysms of the vertebral artery (VA) are primarily unclippable, and proximal ligation or clipping of the VA is the most commonly used method of treatment. In the case of a giant aneurysm, the mass causes severe neurological deficits, and decompression by aneurysmectomy is necessary. When the affected VA is dominant, its proximal occlusion is not a safe procedure. We encountered a case of giant thrombosed aneurysm of the left VA which had caused severe progressive neurological deficits. Trapping of the affected VA and aneurysmectomy were performed immediately following right external carotid artery (ECA)-posterior cerebral artery (PCA) bypass surgery using a radial arterial graft. The details of the surgical approach and techniques used are reported.
I
Case Report This 46-year-old man first complained of headache in June, 1990. He visited one of our affiliated hospitals where computerized tomography (CT) revealed a large enhancing mass of 50 m m in maximum diameter with a calcified wall and a dilated vessel in the posterior fossa (Fig. 1). During the course of his illness, swallowing difficulties and gait disturbances gradually occurred. He 624
giant aneurysm
9 thrombosis
9 bypass procedure
was admitted to the hospital on September 4, 1990, for further examination and operation. Examination. The patient had marked truncal ataxia and dysphagia, but no motor or sensory deficits. Magnetic resonance (MR) imaging revealed the mass clearly displacing the medulla posteriorly, with a small flow-void area in the ventral side (Fig. 2). Vertebral angiograms showed a serpentine aneurysm of the left VA (Fig. 3). The right VA terminated solely in the posterior inferior cerebellar artery (PICA). There was no opacification of the PCA via the posterior communicating arteries (PCoA's). First Operation. A bypass surgical procedure was planned as the initial procedure because the basilar artery was supplied only by the left VA. On September 11, 1990, with the patient in the supine lateral position, a left temporal craniotomy was made. A saphenous vein graft was harvested from the left leg and interposed between the ECA and the left superior cerebellar artery, (SCA). The graft blood flow was 120 cu cm/min. Postoperatively, the patient's condition worsened, necessitating use of a respirator via tracheostomy for I month. The left carotid angiogram performed on the following day showed that the vein graft was occluded. In order to reduce blood flow to the aneurysm, the left VA was exposed in the neck under local anesthesia and
J. Neurosurg. / Volume 77/October, 1992
Giant thrombosed vertebral artery aneurysm
FIG. 1. Preoperative contrast-enhanced computerized tomography scans. Left: The giant aneurysm and the dilated proximal parent artery (arrow) are shown. Right: The giant thrombosed aneurysm measures 50 mm in maximum diameter with a calcified wall.
was ligated at its origin from the subclavian artery after test occlusion. However, the angiogram showed that the serpentine aneurysm and the basilar artery were still well opacified by the collateral flow from the left thyrocervical trunk. The patient was referred to the University Hospital for further therapy on December 14, 1990. During his illness, his orientation deteriorated and a ventriculoperitoneal shunt was inserted for treatment of hydrocephalus, but no remarkable improvement was obtained. The neurological findings on admission were: mild right facial palsy of the central type, bilateral hearing disturbance, dysphagia, mild hypesthesia involving the right side of the face, fight dominant disturbance of position sense, and ataxia of the trunk and extremities. The patient was bedridden.
Second Operation. On February 6, 1991, we performed a craniotomy using an approach essentially the same as that in the third operation (described below). This time, because of further progression of symptoms, a certain degree of decompression was deemed necessary. With the patient in the lateral deeubitus position, a large temporo-occipital skin incision shaped like a question mark and extending to the anterior edge of the right sternocleidomastoid muscle was made and a right temporosuboccipital craniotomy was carried out. A partial mastoidectomy was performed and the mastoid process was removed. The sigmoid sinus was unroofed to the jugular foramen, which was opened posteriorly. The craniectomy was carried inferiorly to the foramen magnum. An extreme lateral approach 7 was made with C-1 hemilaminectomy and by drilling the posterior half of the occipital condyle. In order to expose the left VA proximally, the right VA was mobilized by cutting the dura on both sides of its dural penetration. The distal left VA and basilar artery were visualized by retracting the sigmoid sinus posteriorly. Both the proximal and distal parent arteries were secured. The fifth to 12th cranial nerves had been stretched by the underlying giant aneurysm. The thinned medulla was partly seen overriding the aneurysm, and the ports was displaced cranial to the fifth J. Neurosurg. / Volume 77 / October, 1992
FJ(;. 2. Preoperative magnetic resonance images, axial view (l~ft) and sagittal view (right). The aneurysm is markedly displacing the medulla posteriorly. A flow-void area is recognized in the ventral side of the aneurysm.
FIG. 3. Preoperative left vertebral angiograms, anteroposterior projection (left) and lateral projection (right). The serpentine aneurysm is recognized. The vertebral artery is running from the left to the right upper side.
nerve. The aneurysm wall was cut about 1.5 cm between the seventh and 12th nerves. The content of the thrombosed aneurysm was removed carefully by the ultrasonic aspirator under the guidance of a Doppler flowmeter for determining the course of the VA inside the aneurysm. The portion of the aneurysm that bulged most against the medulla was decompressed to a depth of 2.5 cm. As oozing of blood started inside the aneurysm, debulking was stopped here. The lower medulla was considered to be well decompressed. The aneurysmotomy wound was closed by suture and reinforced with fabricated cotton and fibrin glue. The patient's consciousness disturbance was slightly better postoperatively but the symptoms did not improve much. A postoperative CT scan showed a partial thrombectomy of the aneurysm (Fig. 4). A radical aneurysmectomy for complete decompression was designed because of the additional progressive neurological deficits: left trochlear and accessory nerve palsy, fight hypoglossal nerve palsy, and left hemiparesis; however, this third operation was postponed due to recurrent pneumonia. Third Operation. On May 27, 1991, with the patient in the supine lateral position, the wound from the second operation was reopened and a radial artery bypass was performed from the fight neck ECA to the fight PCA (P2 segment); graft patency was confirmed 625
K. Wakui, el aL
FIG. 4. Computerized tomography scan after the second operation. The low-density area shows the region of partial thrombectomy.
FIc;. 6. Radiographic studies after the third operation.
Upper L{2[L Computerized tomography scan. Space created by the aneurysmeclomy showing a large low-density area. The remaining wall of the aneurysm is seen as a linear high-density area. Upper Right. Magnetic resonance image showing the medulla markedly decompressed. Lower: Right carotid angiograms, anteroposterior view (left) and lateral view (right). There is good patency of the radial arterial graft (arrows) and the basilar arterial system is well opacified.
FIG. 5. Schematic drawing of the third operative view. The aneurysm was trapped with clips and the content of the aneurysm removed. The wall of the aneuusm was resected. VA = vertebral artery; GRAFT = radial arterial graft; PCA = posterior cerebral arteu: BA = basilar artery.; V, VII, and VIII = trigeminal, facial, and acoustic nerves; AICA = anterior inferior cerebellar artery'.
intraoperatively with the Doppler flowmeter. The previous operative wound was densely adherent and it was extremely difficult to find and confirm the important structures. First, the fight VA and PICA were found; they had thrombosed and were black. Then, the contralateral left VA was found. The basilar artery was separated from the aneurysm and the fight anterior inferior cerebellar artery (AICA) was found and dissected free. The aneurysm was trapped with temporary clips placed on the left VA and basilar artery. The aneurysm was entered and the content of the aneurysm was removed, mostly by the ultrasonic aspirator. As we decompressed the aneurysm it became possible to further visualize the inlet and outlet ostia. The trapping clips were replaced closer to the aneurysm. During this process, both AICA's were found and spared from clipping, together with a couple of perforating arteries. These procedures were facilitated by cutting the aneurysm wall. Except for the dorsomedial wall of the aneurysm, which had 626
been attached to the medulla and was mostly calcified, the remaining aneurysm wall was thinned from the inside as much as possible, thus achieving complete decompression (Fig. 5). Patency of the radial arterial graft and the retrograde blood flow of the basilar artery were confirmed with the Doppler flowmeter.
Postoperative Course. The patient showed a gradual improvement of his preoperative deficits (truncal ataxia and left hemiparesis), but severe dysphagia persisted. A C T scan, MR image, and right carotid angiograms showed the posterior fossa well decompressed and good patency of the radial arterial graft through which the basilar arterial system was well opacified (Fig. 6). The patient could sit up in a chair and was discharged 3 months later for further rehabilitation. Left hemiparesis completely disappeared and right facial palsy, hearing disturbance, and dysphagia have gradually improved; he can swallow saliva. He still has truncal ataxia and is now exercising by standing on an inclining bed at our affiliated hospital. Discussion Surgery for giant intracranial aneurysms has three important purposes: reducing the mass effect causing severe neurological deficits; preventing rupture; 3'9 and preventing ischemic complications. 3,1z Direct surgical treatment of giant aneurysms of the VA includes proximal ligation, neck clipping, or aneurysmectomy. 9 The best way to treat an aneurysm is clipping the neck, but giant aneurysms in this location are difficult to clip because temporary trapping is often impossible in a
J. Neurosurg. / Volume 77 / October, 1992
Giant thrombosed vertebral artery aneurysm tight operating feld, especially with regard to securing the distal side of the parent artery; also the aneurysms are usually atherosclerotie, fusiform, or serpentine, with solid thrombosis. Yamaura ~3reported 94 VA aneurysms in 86 patients which were analyzed for their clinical manifestation, diagnosis, and treatment. These included 56 (60%) saccular aneurysms, 26 (28%) dissecting aneurysms, and 12 (13%) atherosclerotic fusiform aneurysms. Dissecting aneurysms and atherosclerotic fusiform aneurysms were primarily unclippable, and proximal clip-occlusion of the VA was the most c o m m o n surgical technique in that series. When the neurological deficits caused by the mass are minimal, even simple ligation of the proximal VA yields a satisfactory result without complications. 468~ If the contralateral VA and the PCoA are well developed, blood supply to the brain stem and cerebellum is sufficient even with the affected VA ligated. However, when the mass causes severe neurological deficits and the affected VA is dominant, bypass surgery L2'5'"; is necessary and decompression by aneurysmectomy or aneurysmotomy is demanded. In the present case, the left ECA-SCA anastomosis was performed as the first step before direct surgical attack on the giant thrombosed aneurysm of the left VA because the basilar artery was supplied only by the affected VA. The saphenous vein graft became occluded the next day, perhaps due to the low pressure gradient between the anastomoses. The decompression of the aneurysm by partial thrombectomy performed as a semi-emergency procedure for progressive symptoms was not satisfactory because we were afraid to enter the blood compartment inside the aneurysm while removing clots. However, surgical exposure of the aneurysm was excellent, with a combined right transmastoid, petrosal, suboccipital, condylar, extreme-lateral approach 7 utilizing pre- and retrosigmoid routes. The left VA and PICA were well opacified on the angiogram through the anastomoses via the muscular branches from the left thyrocervical trunk, even after the proximal ligation at the origin of the left VA. We wanted to avoid injury to the muscular branches in order to preserve the left PICA by approaching the aneurysm from the left side. We judged from the angiogram that the distal parent artery could be secured only from the fight side due to the abnormal course of the left VA (Fig. 3), and that the proximal parent artery could also be visualized and secured by this approach. Both proximal VA's could be secured at the beginning of the direct attack to the aneurysm by the extreme-lateral approach.7 This approach allowed a wide operative view of the aneurysm and facilitated securing both the proximal and distal parent arteries. Almost all the intraluminal clots were evacuated by the ultrasonic aspirator. The Doppler flowmeter is also useful for identifying the course of the blood compartment inside a thrombosed aneurysm or detecting the ostia to the parent artery. J. Neurosurg. / Volume 77 / October, 1992
In the third operation, the right ECA-PCA bypass surgery was performed in the same surgical field. The radial arterial graft may have remained patent in part because it may be a better graft material than the saphenous vein, ~4 and in part because the VA was occluded simultaneously. There were some small perforating vessels from the aneurysm wall but they might not be functionally important. In such cases of thrombosed giant VA aneurysm causing severe progressive neurological deficits where the affected VA is dominant, aneurysmectomy for decompression with trapping of the parent arteries after simultaneous bypass surgery via this combined approach appears to be a safe and satisfactory strategy. References
1. Ausman JI, Lee MC, Chater N, et al: Superficial temporal artery to superior cerebellar artery anastomosis for distal basilar artery stenosis. Surg Neural 12:277-282, 1979 2. Hopkins LN, Budney JL, Castellani D: Extracranial-intracranial arterial bypass and basilar artery ligation in the treatment of giant basilar artery aneurysms. Neurosurgery 13:189-194, 1983 3. Hosobuchi Y: Direct surgical treatment of giant intracranial aneurysms. J Neurosurg 51:743-756, 1979 4. Ishii R, Tanaka R, Koike T, et al: Computed tomographic demonstration of the effect of proximal parent artery ligation for giant intracranial aneurysms. Surg Neuroi 19: 532-540, 1983 5. Lansen TA, Kasoff SS, Arguelles JH: Giant pediatric aneurysm treated with ligation of the middle cerebral artery with the Drake tourniquet and extracranial-intracranial bypass. Nenrosurgery 25:81-85, 1989 6. Massey CE, El Gammal T, Brooks BS: Giant posterior inferior cerebellar artery aneurysm with dysphagia. Surg Neurol 22:467-471, 1984 7. Sen CN, Sekhar LN: An extreme lateral approach to intradural lesions of the cervical spine and foramen magnum. Neurosurgery 27:197-204, 1990 8. Sugita K: Microneurosurgical Atlas. Berlin: Springer-Verlag, 1985, pp 116-135 9. Sugita K, Kobayashi S, Toshiki T, el al: Giant aneurysms of the vertebral artery. Report of five cases. J Neurosurg 68:960-966, 1988 10. Sundt TM Jr, Piepgras DG: Occipital to posterior inferior cerebellar artery bypass surgery. J Nenrosurg 48:916-928, 1978 11. Waga S, Fujimoto K, Morooka Y: Dissecting aneurysm of the vertebral artery. Surg Neural 10:237-239, 1978 12. Whittle IR, Dorsch NW, Besser M: Spontaneous thrombosis in giant intracranial aneurysms. J Neurol Neurosurg Psychiatry 45:1040-1047, 1982 13. Yamaura A: Diagnosis and treatment of vertebral aneurysms. J Neurosarg 69:345-349, 1988 14. Yasui N, Ohta H, Suzuki A, et al: Cervical carotid artery to middle cerebral artery anastomosis with interposed radial artery graft, in Spetzler RF, Carter LP, Selman WR, et al (eds): Cerebral Revascularization for Stroke. New York: Thieme-Stratton, 1985, pp 379-385 Manuscript received November 25, 1991. Accepted in final form March 1I, 1992. Address reprint requests to: Kenji Wakui, M.D., Department of Neumsurgery, Shinshu University School of Medicine, Asahi 3-1-1, Matsumoto 390, Japan. 627
