Neurosurg Focus 18 (2):E3, 2005

Endovascular management of intracranial vertebral dissecting aneurysms

FELIPE C. ALBUQUERQUE, M.D., DAVID J. FIORELLA, M.D., PH.D., PATRICK P. HAN, M.D., VIVEK R. DESHMUKH, M.D., LOUIS J. KIM, M.D., AND CAMERON G. MCDOUGALL, M.D. Division of Neurological , Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona

Object. Intracranial vertebral artery (VA) dissecting aneurysms often present with severe (SAH) and dramatic neurological . The authors reviewed the management of 23 cases in an effort to evaluate treatment efficacy and outcomes. Methods. The records of 23 patients who underwent endovascular treatment were reviewed to determine symptoms, type of therapy, complications, and clinical outcomes. All patients were evaluated using records kept in a prospectively maintained database. Ten men and 13 women (age range 35–72 years; mean age 49 years) were treated over an 8-year period. Twelve patients presented with poor-grade SAH, five with good-grade SAH, three with , and two with . The other patient’s aneurysm was discovered incidentally. Treatment included coil occlusion of the artery at the aneurysm in 21 patients and -assisted coil placement in two. Parent artery sacrifice was successful in all cases, whereas both patients treated with stent-assisted coil insertion suffered recurrences. No patient sustained permanent complications as a result of treatment. Two patients died due to the severity of their original SAH. Findings were normal in 14 patients on follow-up review (including five of the 12 presenting with poor-grade SAH), five had fixed neurological deficits but were able to care for themselves, and one was permanently disabled. Conclusions. Despite their often aggressive neurological presentation, intracranial VA dissecting aneurysms can be managed safely with coil occlusion of the lesion and/or parent artery. Even patients presenting in poor neurological condition may improve dramatically.

KEY WORDS • dissecting aneurysm • vertebral artery aneurysm • endovascular treatment

Dissecting aneurysms of the intracranial VA may man- CLINICAL MATERIAL AND METHODS ifest with severe SAH and devastating neurological se- quelae.11,23 Similarly, unruptured lesions can enlarge and Patient Population produce symptoms due to both compressive and embolic mechanisms.8,11,16,17 These lesions are also associated with The records of 23 patients with dissecting aneurysms a propensity for rerupture in the acute setting,9,11,14,16,20,24 of the fourth segment of the VA, as documented by cere- and consequently, urgent treatment is usually pursued. En- bral , were reviewed. The factors assessed dovascular procedures, including coil occlusion and intra- included clinical history, presentation, presence of SAH cranial stent placement, may obviate the need for complex and its severity, aneurysm location, type of endovascular therapy, radiographically documented success of therapy, skull base approaches. Nonetheless, the anatomy of the V4 segment, specifically the location of the PICA and the and clinical outcome. All patients were evaluated using spinal artery in relation to the aneurysm, determines the records kept in a prospectively maintained database that optimal treatment. We reviewed the efficacy of our inter- was designed to track outcomes and treatment-related ventional management in a consecutive series of 23 pa- complications. tients who were followed using a prospectively main- As shown in Table 1, the patients included 10 men and tained database. We specifically analyzed the type and 13 women treated over an 8-year period by two endovas- success of therapy in a subset of patients who presented in cular neurosurgeons (F.C.A. and C.G.M.). The patients’ moribund condition with severe SAH. ages ranged from 35 to 72 years (mean age 49 years). Twelve patients presented with poor-grade SAH (Hunt and Hess Grade IV or V), whereas five presented with Abbreviations used in this paper: PICA = posterior inferior cere- good-grade SAH (Hunt and Hess Grade I–III).7 Of the bellar artery; SAH = subarachnoid hemorrhage; VA = vertebral six remaining patients, three presented with headache artery. and two with embolic of the posterior circulation.

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TABLE 1 the PICA originated from the segment containing the le- Clinical characteristics, treatment, sion in one patient and the affected VA was dominant and outcome in 23 patients with dissecting VA aneurysms* in the other. According to radiographic studies, treatment was successful in all cases of parent artery occlusion. Both Case No. Age (yrs), Sex Treatment Clinical Outcome patients treated with stent-supported coil occlusion, how- 1 51, F coil occlusion normal ever, had recurrences. Of these, one individual presented 2 35, F coil occlusion functional w/ deficit with recurrent and the other was . 3 36, F coil occlusion normal The former, in whom the affected artery was dominant, 4 54, M coil occlusion NA was treated with parent artery coil occlusion after tolerat- 5 50, M coil occlusion normal ing a balloon test occlusion. The latter patient, whose an- 6 59, F coil occlusion functional w/ deficit 7 53, F coil occlusion functional w/ deficit eurysm affected the origin of the PICA, was treated with 8 38, F coil occlusion functional w/ deficit additional stent placement and coil insertion and remains 9 72, F coil occlusion normal both clinically and radiographically stable. 10 36, M SCD normal 11 48, M SCD normal Complications and Clinical Outcomes 12 40, M coil occlusion normal 13 35, M coil occlusion died No patient suffered a permanent complication as a re- 14 48, F coil occlusion normal sult of endovascular treatment. The patient who required 15 45, M coil occlusion functional w/ deficit additional stent placement and coil insertion for a recur- 16 58, M coil occlusion normal rent aneurysm sustained an iatrogenic, initially flow-lim- 17 38, M coil occlusion normal 18 54, M coil occlusion died iting of the V3 segment as a result of an attempt 19 45, F coil occlusion normal to pass a relatively stiff coronary stent into the distal ar- 20 46, F coil occlusion normal tery. The patient suffered no clinical sequelae of this iat- 21 50, F coil occlusion normal rogenic dissection, and in fact demonstrated spontaneous 22 55, F coil occlusion normal reopening and normal patency of the dissected segment on 23 61, M coil occlusion disabled follow-up angiography performed 24 hours later. Despite * NA = not available; SCD = stent-supported coil delivery. treatment, two of the patients who presented with poor- grade SAH died due to the severity of their original hem- orrhage. The other patient’s aneurysm was incidentally detected on Of the 21 surviving patients, clinical follow-up data computerized tomography scans obtained after blunt head were obtained in 20. The follow-up duration ranged from trauma. 15 days to 49 months (mean 14.6 months). At follow up, findings in 14 patients were normal, five had fixed neuro- Endovascular Procedures logical deficits but were functionally capable of caring for themselves, and one was permanently disabled and depen- Standard endovascular methods of parent artery coil oc- dent on nursing care. The 12 patients who presented with clusion, aneurysm coil occlusion, stent placement, and poor-grade SAH accounted for the five cases of fixed neu- transstent coil delivery were used and are well described 2–5,10,11,13,19,23 rological deficits and the two deaths. The remaining five in the current literature. The type of endovascu- patients in this subset, however, made normal recoveries. lar therapy used varied with the location of the aneurysm in relation to major arterial branches and with the relative dominance of the affected VA. In all cases, careful angio- ILLUSTRATIVE CASES graphic analysis of the contralateral VA both preceded and followed endovascular treatment of the ipsilateral artery. Case 11 This 48-year-old man presented with severe SAH, ob- RESULTS tundation, and . Cerebral angiog- raphy was performed after the patient’s medical condi- Although endovascular therapy was typically instituted tion was stabilized and an external ventricular drain was within hours of the patient’s arrival at our institution, four placed. Angiography revealed a V4 dissecting aneurysm individuals suffered rerupture of their lesions before treat- involving the origin of the PICA (Fig. 1A). In an effort to ment. Fourteen aneurysms were located on the right VA; preserve this vessel, we elected to perform stent-support- of these, eight were proximal to the PICA, four were dis- ed coil embolization (Fig. 1B and C). Despite the gravity tal, and one was located at the origin of the PICA. In the of his original presentation, the patient made a complete other patient with a right-sided aneurysm, no ipsilateral neurological recovery. Follow-up angiography performed PICA was visualized. In the nine patients with left-sided 2 years later, however, demonstrated a significant recur- aneurysms, seven lesions were distal to the PICA and two rence of his aneurysm (Fig. 1D). This recurrence was were proximal. treated with additional stent placement and coil insertion (Fig. 1E and F). The patient remains clinically and radio- Endovascular Treatment graphically stable 3 years after his ictus. Occlusion of the parent artery was performed using transarterial detachable coils deposited at the aneurysm Case 17 site in 21 of 23 patients. In the remaining two, stent-assist- This 38-year-old man was found unconscious at home ed coil occlusion of the aneurysm was undertaken because after suffering an SAH. He presented with obtundation re-

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Fig. 1. Case 11. Preembolization and postembolization angiographic studies. A: Right VA injection revealing a V4 aneurysm at the origin of the PICA. B: Stent-supported coil embolization was performed; note the (arrows). C: After stent-supported coil insertion, normal patency of the artery is maintained and there is almost no flow into the

aneurysm. D: A 24-month follow-up study reveals an enlargement of the aneurysm along the V4 segment involving the PICA. E: Additional stent-supported coil insertion was performed. F: Angiographic study obtained after additional coil delivery and stent placement reveals normal arterial patency and preservation of the PICA. quiring intubation and renal failure related to myoglobin- medical management of his vasospasm, the patient made uria; the latter condition was likely the result of the patient a complete recovery. having suffered his SAH several days before his discov- ery. After his medical condition was stabilized, the patient underwent angiography, which revealed a dissected, dilat- DISCUSSION ed V4 segment of the VA distal to the left PICA (Fig. 2A). Dissections of the intracranial vessels are rare causes The aneurysm was occluded with coils throughout its of SAH, accounting for fewer than 10% of cases.2 Of length, with preservation of the PICA (Fig. 2B and C). these, most involve the posterior circulation, especially Right VA angiography demonstrated severe vasospasm the fourth segment of the VA. These lesions are dynamic; of the basilar artery consistent with the patient’s delayed unruptured aneurysms have a propensity to enlarge, and presentation (Fig. 2D). After receiving endovascular and ruptured lesions have a proclivity to repeated hemor-

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Fig. 2. Case 17. Preembolization and postembolization angiographic studies. A: Left VA angiogram, lateral projec-

tion, revealing a dissecting aneurysm of the left V4 segment just distal to the PICA as well as significant intracranial vasospasm. B: Coil occlusion of the artery at the aneurysm site was performed. C: Left VA angiogram obtained after coil occlusion of the distal parent artery reveals filling of the proximal PICA. D: Right VA angiogram demonstrating filling of the basilar artery. Note the severity of the intracranial vasospasm (arrow).

8,9,11,14,16,20,24 rhage. Researchers estimate the rate of rebleed- The origin of V4 dissecting aneurysms is multifactorial; 9,11,14,16,20,24 ing from V4 aneurysms to be more than 30%. As cases associated with trauma, , and fibromus- 2,20,23 expected, patients suffering rerupture are subject to a dra- cular dysplasia have been reported. Because the V4 matically higher mortality rate (47% compared with 8% region represents the most proximal part of the intracra- of patients without rebleeding).24 nial artery, this segment is likely to be subject to a higher The most common symptom associated with a dissect- degree of traumatic forces at the skull base, such as head 11,16,17 2,20,23 ing V4 aneurysm is headache related to SAH. In such rotation and flexion. Furthermore, the cases, SAH may be severe, often rendering these patients and adventitia of the VA thin as the vessel pierces the moribund at admission. Nonetheless, both ruptured and dura.2 These physical and anatomical factors surely pre- unruptured lesions can manifest with neck pain, cranial dispose this arterial segment to injury and aneurysm for- neuropathies from aneurysm compression, and embolic mation. phenomena producing strokes and transient ischemic at- The high rate of rerupture confirms what has been ob- tacks. served surgically: that these aneurysms are friable and thin

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Unauthenticated | Downloaded 09/25/21 07:45 PM UTC Endovascular management of intracranial VA dissecting aneurysms walled.11 Histological studies reveal widespread disrup- potential complications. We reported a case of a recurrent 15,25 tion of the internal elastic lamina. This disruption even- left-sided V4 aneurysm (Case 10) initially treated with tually produces a dissection plane between the tunica me- stent-supported coil placement that eventually required dia and the adventitia.2,15,25 Rupture into the adventitia is coil occlusion of the parent artery after successful balloon a typical finding. Surgical evaluation of these aneurysms test occlusion.11 The patient in Case 11, the second one often reveals several perforating arising from the treated with stent-supported coil insertion, also suffered a diseased segment.8 These small arteries tend to be throm- recurrence and underwent further stent placement and coil bosed or occluded, explaining why patients can usually insertion because the PICA was involved in the segment tolerate coil occlusion of the affected segment.8 Autopsy containing the aneurysm. These two cases underscore the analysis indicates that healing occurs through neointimal fact that these aneurysms are delicate and prone to re- hyperplasia, starting 1 week after injury and lasting longer growth, most likely because their adventitial walls fail to than 1 month.12,15,25 This protracted process further con- restrict enlargement.15,25 tributes to the high rate of repeated hemorrhage. Because of these two treatment failures, we prefer sur- Several angiographic features must be considered be- gical bypass, especially a PICA–PICA anastomosis, fol- fore selecting the optimal treatment for V4 dissecting an- lowed by either surgical clip placement or coil occlusion eurysms. These lesions have a variable angiographic ap- of the aneurysm.6 In patients with contraindications to pearance, most often demonstrating a region of vessel open surgery or in cases with complex anatomical fea- tapering and then enlargement, also known as a “pearl tures, stent-supported coil embolization should be per- and string” configuration.20,24 This particular configuration formed with careful, routine follow-up angiography to 20,24 5,10,19 has the highest propensity for rerupture. The V4 an- evaluate for a recurrence. Likewise, when the affected eurysms may also demonstrate fusiform dilation, severe artery is dominant, we favor balloon test occlusion fol- vessel narrowing, and even occlusion.20,24 Irregularities lowed by permanent coil occlusion at the site of the an- such as aneurysm dilation and vessel tapering actually eurysm if the patient can tolerate this treatment.11,26 Pa- facilitate transarterial coil placement, because both fea- tients in whom test occlusion fails should undergo a tures allow the coils to conform to the diseased segment. bypass procedure, followed by either surgical or endovas- Other and perhaps more important angiographic fea- cular occlusion of the aneurysm. In patients suffering tures include the location of the aneurysm in relation from obtundation who are unable to cooperate during test to the PICA and the spinal artery as well as the status of occlusion, surgical or endovascular therapy should be tai- the contralateral artery.18,26 Aneurysm involvement of the lored to the clinical scenario, with the goal of selecting the PICA or spinal arterial segment precludes a deconstruc- treatment that offers the highest benefit and poses the least tive treatment such as coil occlusion of the artery at the risk to the patient.26 aneurysm site. Similarly, the dominance of the affected A surprising finding in this study was the high number artery complicates the treatment paradigm. In such cases, of critically ill patients who eventually recovered func- balloon test occlusion is helpful in assessing the risk of tionally. Of this subset of 12 patients, five actually recov- stroke after vessel sacrifice.11 ered completely. Although the literature documents that

Initially, V4 aneurysms were treated with hunterian lig- patients presenting in extremis usually do poorly, this neg- ation of the proximal artery.1,2,11 This simple alteration ative expectation must be tempered by the prospect of of flow dynamics often successfully produced substantial recovery.9,11,14,16,20,24 An SAH within the posteri- of the aneurysm. Nevertheless, aneurysm growth and re- or fossa is more likely to affect the and to pro- can follow proximal ligation. This possibility duce a dramatically poor neurological picture. In our se- prompted direct surgical approaches to the aneurysm for ries, patients who recovered from severe posterior fossa clip placement and wrapping.1,11 The complexity of these SAH tended to demonstrate signs of improvement within approaches and their high attendant morbidity and mortal- hours of their ictus. The potential for substantial recovery ity rates hastened the advent of endovascular treatment. and the high rate of acute rerupture should prompt urgent

Endovascular therapy of V4 aneurysms evolved in a treatment of patients harboring these aneurysms. similar fashion to surgical endeavors. At first, the affected artery was occluded proximally by using either detach- CONCLUSIONS able balloons or coils.8,11,22 This paradigm was again limit- ed by cases of aneurysm recurrence and repeated hemor- Coil occlusion of the aneurysm and parent artery is the rhage.8,11,22 Subsequently, coil occlusion of the artery at treatment of choice in patients harboring dissecting le- the lesion site was adopted in patients in whom the an- sions of the fourth segment of the VA. This procedure is eurysm location was distinct from the origin of the PICA associated with a very low rate of complications and a and the spinal artery.11 Cases involving either of the afore- high rate of technical success. In patients whose aneu- mentioned sites mandate a reconstructive endovascular rysms involve critical arterial branches or the dominant approach. Typically, stent-supported coil embolization is VA, attention should be turned to open surgical alterna- performed.2,10,19,21 Other techniques such as double stent tives such as bypass. Stent-supported coil insertion is as- insertion and covered stent placement have been used less sociated with aneurysm recurrence and should be reserved frequently.2–4,13,21 The former has been associated with a for patients in whom surgery is contraindicated, and used higher rate of thromboembolic complications and the lat- only when careful follow-up angiography can be per- ter with in-stent .3–5,13 formed. Patients suffering from these lesions often recov- Despite the development of flexible stents specifically er as dramatically as they present, and most should be designed for navigation in the central nervous system, the treated in an urgent fashion to diminish the likelihood of use of stents in this scenario is associated with its own repeated hemorrhage.

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