P e d i a t r i c C e re b r a l A n e u r y s m s Joseph J. Gemmete, MD, FSIRa,*, Ahmed K. Toma, MD, FRCS (Neurosurg)b, Indran Davagnanam, MD, MB BCh, BAO, BMedSci, FRCRc, Fergus Robertson, MRCP, FRCRc, Stefan Brew, MBBS, MHB, MSc, FRANZCR, FRCRc KEYWORDS Pediatric aneurysm SAH Intracranial cerebral aneurysm Endovascular treatment
KEY POINTS Childhood intracranial aneurysms are rare. They are distinct pathologically from adult aneurysms. They are associated with other congenital diseases. They have a higher incidence of de novo growth and recurrence. The endovascular method is the main treatment modality.
INTRODUCTION Intracranial aneurysms in children are rare. (Table 1) shows the larger series of intracranial pediatric aneurysms to date. Most of the risk factors associated with intracranial aneurysms in adults do not exist in children, therefore the pathogenesis is thought to be different. The location and size of intracranial aneurysms in children differ from those found in adults. Most children with intracranial aneurysms present with subarachnoid hemorrhage (SAH) typically with a good clinical grade. This article reviews the incidence and gender prevalence, cause, location, and different types of intracranial aneurysms in children. The clinical presentation, diagnosis, and treatment of intracranial aneurysms in children are discussed, and data from endovascular treatments are presented.
INCIDENCE AND GENDER PREVALENCE Intracranial aneurysms in children are rare; 0.5% to 4.6% of intracranial aneurysms occur in patients
aged 18 years or younger.1–4 In a cooperative study reported in 1966, only 41 of 6368 (0.6%) ruptured aneurysms were found in patients younger than 19 years.5 In children, boys are more likely to harbor aneurysms than are girls.2,6–8 After puberty, women have a 3 to 5 times higher incidence of aneurysms than men.9,10 In some reports, a female dominance has been found before the age of 2 years.11 Other reports that include older children have shown a less evident male dominance.12
CAUSES Cerebral aneurysms are often thought to form as a result of chronic hemodynamic stress at branch points of arteries or areas where arteries abruptly change curvature. The classic risk factors in adults are largely acquired, such as hypertension, obesity, high cholesterol, diabetes, alcohol abuse, and smoking, and are often absent in children. Many pediatric patients have medical comorbidities that may be related to an underlying genetic
Grants: None. a Division of Interventional Neuroradiology and Cranial Base Surgery, Departments of Radiology, Neurosurgery, and Otolaryngology, University of Michigan Health System, UH B1D 328, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5030, USA; b Victor Horsley Department of Neurosurgery, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, UK; c Lysholm Department of Neuroradiology, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, UK * Corresponding author. E-mail address: [email protected] Neuroimag Clin N Am 23 (2013) 771–779 http://dx.doi.org/10.1016/j.nic.2013.03.018 1052-5149/13/$ – see front matter Ó 2013 Elsevier Inc. All rights reserved.
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Table 1 Largest recent series of pediatric aneurysms Lasjaunias et al,11 Hetts et al,18 2005 2009 Patients (n) Number of aneurysms Age (range) Sex Morphology Fusiform (%) Saccular (%) Infectious (%) Traumatic (%) Giant (>25 mm) (%) Multiple (%) Anterior Circulation (%) Posterior Circulation (%) SAH (%) Mass Effect (%) Mortality (%)
Koroknay-Pal et al,20 2012
Mehrotra et al,19 2012
59 75 7.6 y (8 d–15 y) M/F 3:2
77 114 103 130 12 y (3 mo–18 y) 14.5 y (3 mo–18 y) F/M 1.1:1 M/F 3:2
57 73 12.7 y (4 y–18 y) M/F 1:1.2
56 27 14 3 1.3 15 73 27 54 — 10.4
31 46 12 14 11 16 78 22 32 — 1.3
2.7 78 2.7 8 19 11 71.3 28.7 88.7 7 8.7
abnormality or developmental defect in the arterial tissue. Such factors might predispose these patients to aneurysm formation at a faster rate than that in patient without these factors, accounting for their earlier clinical presentation. Pediatric aneurysms are associated with conditions such as polycystic kidney disease, fibromuscular dysplasia, Ehlers-Danlos syndrome, Klippel-Tre´naunay syndrome, tuberous sclerosis, moyamoya syndrome, hereditary hemorrhagic telangiectasia, pseudoxanthoma elasticum, or Marfan disease.13,14 There is also a higher incidence of traumatic aneurysm. Aneurysms are called saccular or berry when they have a saccular appearance, and dissecting when the aneurysm has a fusiform appearance and has preaneurysmal or postaneurysmal narrowing.12 Childhood cerebral aneurysms are morphologically different from their saccular counterparts in adults, including a high number of fusiform shape, giant size, and de novo formation. Dissecting aneurysms are dominant during the first 5 years of life, whereas saccular aneurysms are more common in children older than 6 years.
ANEURYSM FEATURES The size and location of aneurysms in children are different than those found in the adult population. Aneurysms of the internal carotid artery (ICA) occur with similar frequency in both populations;
10 78 0 7.6 12 11 89 11 78.1 6.1 7.7
however, there is a greater incidence of ICA terminus aneurysms in the pediatric population.2,7,15–20 Aneurysms of the anterior cerebral artery (ACA) including the anterior communicating artery occur 34% of the time in the adult population, whereas, in children, recent reviews have encountered ACA aneurysms only about 5% to 10% of the time.9,21 Aneurysms involving the middle cerebral artery occur in a similar distribution in both adults and children. Posterior circulation aneurysms are more common in children, occurring approximately 25% of the time.6,8,11,12,16,22,23 In contrast, in the adult population they occur in only 8% of patients presenting with an aneurysm. The multiplicity of saccular aneurysms in children is low compared with adults, except in children with aneurysms of infectious origin.11,12,24,25 In our series, 33% of aneurysms were located in the ICA, 33% in the middle cerebral artery, 17% in the posterior cerebral artery, 8% in the posterior communicating artery, and 8% in the basilar artery.
Traumatic Aneurysms Traumatic aneurysms account for about 5% to 40% of pediatric aneurysms.12,18,23,25–27 These aneurysms usually involve the distal ACA adjacent to the falx (40%), involve the major vessels along the skull base (35%), or have a cortical location (25%).27–29 The child usually presents with a
Pediatric Cerebral Aneurysms hemorrhagic episode about 4 weeks after the initial injury; however, immediate bleeding has also been reported.30 Most children have sustained a closed head injury, but other causes include penetrating injuries and surgery.30,31
Infectious Aneurysms Infectious aneurysms account for 5% to 15% of pediatric aneurysms.11,18,26,32 They are most often of bacterial origin.33–35 The most common organism is staphylococcus, followed by streptococcus and other gram-negative organisms.24 Infectious arterial aneurysms are usually caused by bacterial
endocarditis in infants with congenital or rheumatic heart disease. Infections involving the sphenoid sinus or mastoid air cells and sinus thrombophlebitis may also involve the adjacent artery causing an infectious aneurysm.12,36,37 Infectious arterial aneurysms have also been observed in children with chronic mucocutaneous candidiasis and human immunodeficiency virusinfection.38–43
Saccular Aneurysms Saccular aneurysms are the most common type of aneurysm occurring in the pediatric population
Fig. 1. An 8-year-old girl who presented with worst headache of her life from a grade 3 Hunt and Hess SAH. (A) Lateral view of a selective internal carotid angiogram shows a posterior communicating artery (PCOM) aneurysm. (B) Final angiogram shows the aneurysm coiled to exclusion with preservation of the PCOM artery. (C) A 6-month follow-up angiogram shows persistent exclusion of the aneurysm with patent PCOM artery.
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Gemmete et al (between 46% and 70%).11,12,24,26 The cause of saccular aneurysms is unknown. They usually occur at bifurcation points of vessels, suggesting hemodynamic factors.10,21
Dissecting Aneurysms (Nontraumatic) Dissecting aneurysms in the pediatric population occur 4 times more often than in the adult population.11,12 This type of aneurysm can occur in the anterior or posterior circulation, especially the P1 and P2 segments of the posterior cerebral artery, supraclinoid ICA, and middle cerebral artery. Hetts
and colleagues,18 in the largest reported series, evaluated 77 patients with 103 intracranial aneurysms and showed a greater incidence of dissecting aneurysms in the anterior circulation. Lasjaunias and colleagues,11 in their series of 59 consecutive children with 79 aneurysms, showed an almost equal distribution between the anterior and posterior circulation. Agid and colleagues,12 in their series of 33 patients with 37 aneurysms, showed that most dissecting aneurysms involve the posterior circulation. There are reports of dissecting aneurysms in children healing spontaneously with occlusion of the parent artery.44
Fig. 2. A 4-year-old boy who presented with a headache from a grade 2 Hunt and Hess SAH. (A) Selective vertebral artery angiogram shows a left posterior cerebral artery (PCA) aneurysm. (B) Selective PCA angiogram shows the aneurysm at the P2/P3 segment. (C) Lateral spot fluoroscopic images shows the Histoacryl glue within the aneurysm and adjacent PCA segment. (D) Final vertebral angiogram confirming exclusion of the aneurysm with arterial collaterals supplying left PCA territory.
Pediatric Cerebral Aneurysms Giant Aneurysms
DIAGNOSIS
Giant aneurysms (>25 mm) in children are about 4 times more common than in adults.22,25,45–47 Their reported incidence in children is between 25% and 45%.48 Giant aneurysms should be considered in the dissection category. Children who have giant aneurysms often present with mass effect and only 35% of the time with SAH.12,18,49
For a child with suspected SAH, the diagnosis begins with a noncontrast computed tomography (CT) scan of the head. If this study is normal and the clinical history is strongly suspicious for SAH, then a lumbar puncture is required. The presence of xanthochromia or blood requires additional imaging in the form of a CT angiogram or a magnetic resonance (MR) angiogram of the circle of Willis. The choice of imaging modality is made on a case-by-case basis with an effort to reduce unnecessary radiation exposure while obtaining the necessary data to plan treatment and postoperative management. Digital subtraction angiography (DSA) is still the gold standard for the diagnosis of cerebral aneurysms. For patients with unruptured aneurysms who may present with headache, seizures, or mass effect, MR imaging of the brain with an MR angiogram of the circle of Willis is valuable to limit radiation exposure because these patients may need long-term follow-up imaging.
NATURAL HISTORY Given the pediatric patient’s lifespan, the cumulative risks of aneurysm growth, rupture, recurrence, de novo aneurysm formation, and retreatment are considerable, hence treatment and posttreatment follow-up are mandatory.
CLINICAL PRESENTATION Children with intracranial aneurysms can present with SAH, headache, direct compressive effects, focal neurologic deficits, or seizures.19 Sixty percent of children with SAH have a cerebral aneurysm.50 Fusiform aneurysms tend to present with nonhemorrhagic deficits.18 Many children with SAH present with a Hunt and Hess grade between 1 and 3.11,12,47,48,51 The reason for the better clinical grade at presentation is unclear, but this may be related to fewer comorbidities, a superior nitric oxide synthase pathway, or the robustness of the leptomeningeal arterial collaterals.11,52 In our series, 56% of patients presented with SAH, 33% with mass effect, and 11% after trauma.
TREATMENT In the past, aneurysms have been treated surgically, with either excision or clipping of the aneurysmal segment. In recent years there has been a shift toward the use of endovascular intervention with a strong desire to avoid open surgery in young children. A multidisciplinary team consisting of stroke neurologists, cerebrovascular neurosurgeons, and neurointerventional radiologists is
Fig. 3. A 9-month-old boy who presented with left-sided weakness. (A) Axial fluid-attenuated inversion recovery MR image of the brain shows a large flow void in the right M1 segment. (B) Three-dimensional time of flight MR angiogram shows a wide-necked saccular aneurysm involving the right M1 segment.
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Fig. 3. (C) Right internal carotid angiogram shows a wide-necked saccular aneurysm involving the right M1 segment. (D) Right internal carotid angiogram shows an enterprise stent from the distal right M1 segment across the neck of the aneurysm extending into the supraclinoid ICA with coils within the aneurysm. (E) Final right internal carotid angiogram after embolization shows filling at the base of the aneurysm with a small filling defect within the distal stent.
mandatory to treat complex intracranial aneurysms and achieve excellent results.53 Treatment options include observation, endovascular therapy, or surgical clipping. The treatment modality depends on location, vascular anatomy, and aneurysm shape. Surgical treatment includes direct clipping, clip reconstruction, and aneurysm trapping with or without bypass procedures. For endovascular treatment, we generally use a femoral approach, using a 4-Fr to 6-Fr access system. Cerebral angiography and aneurysm catheterization techniques are similar to those used in adults apart from the careful use of contrast
according to child size. Other specific issues related to small children include the careful monitoring of blood loss and fluid requirements. Simple coiling with or without adjuvant techniques such as balloon remodeling or stent placement are primarily used for most aneurysms (Fig. 1); however, glue is used for distal fusiform aneurysms (Fig. 2). Stents, including flow-diverting stents, may be necessary for fusiform and giant aneurysms (Fig. 3). In our series, 8 patients were treated with endovascular techniques, and 1 was managed conservatively, because risk of treatment was considered to outweigh the benefit. Endovascular techniques
Pediatric Cerebral Aneurysms included coil (n 5 5) or glue (n 5 1) embolization, stent coiling (n 5 1), and balloon occlusion (n 5 1).
OUTCOME In our series, 6 of the patients had an excellent outcome, 1 was left severely disabled, and 2 patients died. Of the 2 patients who died, 1 was managed conservatively, and the other rebled during the occlusion procedure. In the Toronto series, children treated by an endovascular approach had a better clinical outcome than those in the surgically treated group.12 Seventy-seven percent of the patients who received endovascular treatment made a good recovery (modified Rankin scale 0–1) compared with 44.4% of patients treated with open surgery. Lasjaunias and colleagues11 also reported good long-term results and outcome in their endovascular-treated aneurysms. Saraf and colleagues,54 in a study of 23 pediatric patients with intracranial aneurysms, showed an overall favorable outcome in 22 of 23 treated with endovascular techniques. A report from China of 22 patients with intracranial aneurysms treated by endovascular techniques showed a good outcome in 96% of patients with a Glasgow Outcome Scale of 4 or 5.55
SUMMARY Childhood intracranial aneurysms differ from those in the adult population in incidence and gender prevalence, cause, location, and clinical presentation. Endovascular treatment of pediatric aneurysms is the suggested approach because it offers both reconstructive and deconstructive techniques and a better clinical outcome compared with surgery; however, the long-term durability of endovascular treatment is still questionable, therefore long-term clinical and imaging follow-up is necessary.
REFERENCES 1. Locksley HB, Sahs AL, Knowler L. Report on the cooperative study of intracranial aneurysms and subarachnoid hemorrhage. Section II. General survey of cases in the central registry and characteristics of the sample population. J Neurosurg 1966; 24:922–32. 2. Gerosa M, Licata C, Fiore DL, et al. Intracranial aneurysms of childhood. Childs Brain 1980;6: 295–302. 3. Roche JL, Choux M, Czorny A, et al. Intracranial arterial aneurysm in children. A cooperative study. Apropos of 43 cases. Neurochirurgie 1988;34: 243–51 [in French].
4. Sedzimir CB, Robinson J. Intracranial hemorrhage in children and adolescents. J Neurosurg 1973; 38:269–81. 5. Locksley HB. Natural history of subarachnoid hemorrhage, intracranial aneurysms and arteriovenous malformations. Based on 6368 cases in the cooperative study. J Neurosurg 1966;25:219–39. 6. Meyer FB, Sundt TM Jr, Fode NC, et al. Cerebral aneurysms in childhood and adolescence. J Neurosurg 1989;70:420–5. 7. Patel AN, Richardson AE. Ruptured intracranial aneurysms in the first two decades of life. A study of 58 patients. J Neurosurg 1971;35:571–6. 8. Amacher LA, Drake CG. Cerebral artery aneurysms in infancy, childhood and adolescence. Childs Brain 1975;1:72–80. 9. Molyneux A, Kerr R, Stratton I, et al. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 2002;360:1267–74. 10. Unruptured intracranial aneurysms–risk of rupture and risks of surgical intervention. International Study of Unruptured Intracranial Aneurysms Investigators. N Engl J Med 1998;339:1725–33. 11. Lasjaunias P, Wuppalapati S, Alvarez H, et al. Intracranial aneurysms in children aged under 15 years: review of 59 consecutive children with 75 aneurysms. Childs Nerv Syst 2005;21:437–50. 12. Agid R, Souza MP, Reintamm G, et al. The role of endovascular treatment for pediatric aneurysms. Childs Nerv Syst 2005;21:1030–6. 13. Pope FM, Kendall BE, Slapak GI, et al. Type III collagen mutations cause fragile cerebral arteries. Br J Neurosurg 1991;5:551–74. 14. Taira T, Tamura Y, Kawamura H. Intracranial aneurysm in a child with Klippel-Trenaunay-Weber syndrome: case report. Surg Neurol 1991;36: 303–6. 15. Pasqualin A, Mazza C, Cavazzani P, et al. Intracranial aneurysms and subarachnoid hemorrhage in children and adolescents. Childs Nerv Syst 1986; 2:185–90. 16. Storrs BB, Humphreys RP, Hendrick EB, et al. Intracranial aneurysms in the pediatric age-group. Childs Brain 1982;9:358–61. 17. Almeida GM, Pindaro J, Plese P, et al. Intracranial arterial aneurysms in infancy and childhood. Childs Brain 1977;3:193–9. 18. Hetts SW, Narvid J, Sanai N, et al. Intracranial aneurysms in childhood: 27-year single-institution experience. AJNR Am J Neuroradiol 2009;30: 1315–24. 19. Mehrotra A, Nair AP, Das KK, et al. Clinical and radiological profiles and outcomes in pediatric patients with intracranial aneurysms. J Neurosurg Pediatr 2012;10:340–6.
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Gemmete et al 20. Koroknay-Pal P, Lehto H, Niemela M, et al. Long-term outcome of 114 children with cerebral aneurysms. J Neurosurg Pediatr 2012;9: 636–45. 21. Wiebers DO, Whisnant JP, Huston J 3rd, et al. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet 2003;362:103–10. 22. Allison JW, Davis PC, Sato Y, et al. Intracranial aneurysms in infants and children. Pediatr Radiol 1998;28:223–9. 23. Agid R, Terbrugge K. Pediatric aneurysms. J Neurosurg 2007;106:328 [author reply: 9]. 24. Choux M, Lena G, Genitori L. Intracranial aneurysms in children. In: Raimondi A, Choux M, Di Rocco C, editors. Cerebrovascular disease in children. Vienna (Austria): Springer; 1992. p. 123–31. 25. Lasjaunias P, Campi A, Rodesch G, et al. Aneurysmal disease in children: review of 20 cases with intracranial arterial localisations. Interv Neuroradiol 1997;3:215–29. 26. Herman JM, Rekate HL, Spetzler RF. Pediatric intracranial aneurysms: simple and complex cases. Pediatr Neurosurg 1991;17:66–72 [discussion: 3]. 27. Yazbak PA, McComb JG, Raffel C. Pediatric traumatic intracranial aneurysms. Pediatr Neurosurg 1995;22:15–9. 28. Ventureyra EC, Higgins MJ. Traumatic intracranial aneurysms in childhood and adolescence. Case reports and review of the literature. Childs Nerv Syst 1994;10:361–79. 29. Nakstad P, Nornes H, Hauge HN. Traumatic aneurysms of the pericallosal arteries. Neuroradiology 1986;28:335–8. 30. Kneyber MC, Rinkel GJ, Ramos LM, et al. Early posttraumatic subarachnoid hemorrhage due to dissecting aneurysms in three children. Neurology 2005;65:1663–5. 31. Sutton LN. Vascular complications of surgery for craniopharyngioma and hypothalamic glioma. Pediatr Neurosurg 1994;21(Suppl 1):124–8. 32. Kanaan I, Lasjaunias P, Coates R. The spectrum of intracranial aneurysms in pediatrics. Minim Invasive Neurosurg 1995;38:1–9. 33. Barrow DL, Prats AR. Infectious intracranial aneurysms: comparison of groups with and without endocarditis. Neurosurgery 1990;27:56–73. 34. Bohmfalk GL, Story JL, Wissinger JP, et al. Bacterial intracranial aneurysm. J Neurosurg 1978;48: 369–82. 35. Horten BC, Abbott GF, Porro RS. Fungal aneurysms of intracranial vessels. Arch Neurol 1976; 33:577–9. 36. Suwanwela C, Suwanwela N, Charuchinda S, et al. Intracranial mycotic aneurysms of extravascular origin. J Neurosurg 1972;36:552–9.
37. Marsot-Dupuch K, Riachi S, Berthet K, et al. Infectious aneurysms of the cavernous carotid artery. J Radiol 2000;81:891–8 [in French]. 38. Leroy D, Dompmartin A, Houtteville JP, et al. Aneurysm associated with chronic mucocutaneous candidiasis during long-term therapy with ketoconazole. Dermatologica 1989;178:43–6. 39. Grouhi M, Dalal I, Nisbet-Brown E, et al. Cerebral vasculitis associated with chronic mucocutaneous candidiasis. J Pediatr 1998;133:571–4. 40. Philippet P, Blanche S, Sebag G, et al. Stroke and cerebral infarcts in children infected with human immunodeficiency virus. Arch Pediatr Adolesc Med 1994;148:965–70. 41. Dubrovsky T, Curless R, Scott G, et al. Cerebral aneurysmal arteriopathy in childhood AIDS. Neurology 1998;51:560–5. 42. Shah SS, Zimmerman RA, Rorke LB, et al. Cerebrovascular complications of HIV in children. AJNR Am J Neuroradiol 1996;17:1913–7. 43. Park YD, Belman AL, Kim TS, et al. Stroke in pediatric acquired immunodeficiency syndrome. Ann Neurol 1990;28:303–11. 44. Tanabe M, Inoue Y, Hori T. Spontaneous thrombosis of an aneurysm of the middle cerebral artery with subarachnoid haemorrhage in a 6-year-old child: case report. Neurol Res 1991;13:202–4. 45. Amacher AL, Drake CG, Ferguson GG. Posterior circulation aneurysms in young people. Neurosurgery 1981;8:315–20. 46. Heiskanen O, Vilkki J. Intracranial arterial aneurysms in children and adolescents. Acta Neurochir (Wien) 1981;59:55–63. 47. Proust F, Toussaint P, Garnieri J, et al. Pediatric cerebral aneurysms. J Neurosurg 2001;94:733–9. 48. Huang J, McGirt MJ, Gailloud P, et al. Intracranial aneurysms in the pediatric population: case series and literature review. Surg Neurol 2005;63:424–32 [discussion: 32–3]. 49. Peerless SJ, Nemoto S, Drake CG. Giant intracranial aneurysms in children and adolescents. In: Edwards MS, Hoffman HJ, editors. Cerebral vascular disease in children and adolescents. Baltimore (MD): Williams and Wilkins; 1989. 50. Jordan LC. Assessment and treatment of stroke in children. Curr Treat Options Neurol 2008;10: 399–409. 51. Krishna H, Wani AA, Behari S, et al. Intracranial aneurysms in patients 18 years of age or under, are they different from aneurysms in adult population? Acta Neurochir (Wien) 2005;147:469–76 [discussion: 76]. 52. Khurana VG, Meissner I, Sohni YR, et al. The presence of tandem endothelial nitric oxide synthase gene polymorphisms identifying brain aneurysms more prone to rupture. J Neurosurg 2005;102: 526–31.
Pediatric Cerebral Aneurysms 53. Johnston SC. Effect of endovascular services and hospital volume on cerebral aneurysm treatment outcomes. Stroke 2000;31:111–7. 54. Saraf R, Shrivastava M, Siddhartha W, et al. Intracranial pediatric aneurysms: endovascular
treatment and its outcome. J Neurosurg Pediatr 2012;10:230–40. 55. Liang JT, Bao YH, Zhang HQ, et al. Intracranial aneurysms in childhood and adolescence. Zhonghua Yi Xue Za Zhi 2011;91:2744–6 [in Chinese].
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KEY POINTS Childhood intracranial aneurysms are rare. They are distinct pathologically from adult aneurysms. They are associated with other congenital diseases. They have a higher incidence of de novo growth and recurrence. The endovascular method is the main treatment modality.
INTRODUCTION Intracranial aneurysms in children are rare. (Table 1) shows the larger series of intracranial pediatric aneurysms to date. Most of the risk factors associated with intracranial aneurysms in adults do not exist in children, therefore the pathogenesis is thought to be different. The location and size of intracranial aneurysms in children differ from those found in adults. Most children with intracranial aneurysms present with subarachnoid hemorrhage (SAH) typically with a good clinical grade. This article reviews the incidence and gender prevalence, cause, location, and different types of intracranial aneurysms in children. The clinical presentation, diagnosis, and treatment of intracranial aneurysms in children are discussed, and data from endovascular treatments are presented.
INCIDENCE AND GENDER PREVALENCE Intracranial aneurysms in children are rare; 0.5% to 4.6% of intracranial aneurysms occur in patients
aged 18 years or younger.1–4 In a cooperative study reported in 1966, only 41 of 6368 (0.6%) ruptured aneurysms were found in patients younger than 19 years.5 In children, boys are more likely to harbor aneurysms than are girls.2,6–8 After puberty, women have a 3 to 5 times higher incidence of aneurysms than men.9,10 In some reports, a female dominance has been found before the age of 2 years.11 Other reports that include older children have shown a less evident male dominance.12
CAUSES Cerebral aneurysms are often thought to form as a result of chronic hemodynamic stress at branch points of arteries or areas where arteries abruptly change curvature. The classic risk factors in adults are largely acquired, such as hypertension, obesity, high cholesterol, diabetes, alcohol abuse, and smoking, and are often absent in children. Many pediatric patients have medical comorbidities that may be related to an underlying genetic
Grants: None. a Division of Interventional Neuroradiology and Cranial Base Surgery, Departments of Radiology, Neurosurgery, and Otolaryngology, University of Michigan Health System, UH B1D 328, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5030, USA; b Victor Horsley Department of Neurosurgery, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, UK; c Lysholm Department of Neuroradiology, National Hospital for Neurology & Neurosurgery, University College London Hospitals, Queen Square, London, UK * Corresponding author. E-mail address: [email protected] Neuroimag Clin N Am 23 (2013) 771–779 http://dx.doi.org/10.1016/j.nic.2013.03.018 1052-5149/13/$ – see front matter Ó 2013 Elsevier Inc. All rights reserved.
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Table 1 Largest recent series of pediatric aneurysms Lasjaunias et al,11 Hetts et al,18 2005 2009 Patients (n) Number of aneurysms Age (range) Sex Morphology Fusiform (%) Saccular (%) Infectious (%) Traumatic (%) Giant (>25 mm) (%) Multiple (%) Anterior Circulation (%) Posterior Circulation (%) SAH (%) Mass Effect (%) Mortality (%)
Koroknay-Pal et al,20 2012
Mehrotra et al,19 2012
59 75 7.6 y (8 d–15 y) M/F 3:2
77 114 103 130 12 y (3 mo–18 y) 14.5 y (3 mo–18 y) F/M 1.1:1 M/F 3:2
57 73 12.7 y (4 y–18 y) M/F 1:1.2
56 27 14 3 1.3 15 73 27 54 — 10.4
31 46 12 14 11 16 78 22 32 — 1.3
2.7 78 2.7 8 19 11 71.3 28.7 88.7 7 8.7
abnormality or developmental defect in the arterial tissue. Such factors might predispose these patients to aneurysm formation at a faster rate than that in patient without these factors, accounting for their earlier clinical presentation. Pediatric aneurysms are associated with conditions such as polycystic kidney disease, fibromuscular dysplasia, Ehlers-Danlos syndrome, Klippel-Tre´naunay syndrome, tuberous sclerosis, moyamoya syndrome, hereditary hemorrhagic telangiectasia, pseudoxanthoma elasticum, or Marfan disease.13,14 There is also a higher incidence of traumatic aneurysm. Aneurysms are called saccular or berry when they have a saccular appearance, and dissecting when the aneurysm has a fusiform appearance and has preaneurysmal or postaneurysmal narrowing.12 Childhood cerebral aneurysms are morphologically different from their saccular counterparts in adults, including a high number of fusiform shape, giant size, and de novo formation. Dissecting aneurysms are dominant during the first 5 years of life, whereas saccular aneurysms are more common in children older than 6 years.
ANEURYSM FEATURES The size and location of aneurysms in children are different than those found in the adult population. Aneurysms of the internal carotid artery (ICA) occur with similar frequency in both populations;
10 78 0 7.6 12 11 89 11 78.1 6.1 7.7
however, there is a greater incidence of ICA terminus aneurysms in the pediatric population.2,7,15–20 Aneurysms of the anterior cerebral artery (ACA) including the anterior communicating artery occur 34% of the time in the adult population, whereas, in children, recent reviews have encountered ACA aneurysms only about 5% to 10% of the time.9,21 Aneurysms involving the middle cerebral artery occur in a similar distribution in both adults and children. Posterior circulation aneurysms are more common in children, occurring approximately 25% of the time.6,8,11,12,16,22,23 In contrast, in the adult population they occur in only 8% of patients presenting with an aneurysm. The multiplicity of saccular aneurysms in children is low compared with adults, except in children with aneurysms of infectious origin.11,12,24,25 In our series, 33% of aneurysms were located in the ICA, 33% in the middle cerebral artery, 17% in the posterior cerebral artery, 8% in the posterior communicating artery, and 8% in the basilar artery.
Traumatic Aneurysms Traumatic aneurysms account for about 5% to 40% of pediatric aneurysms.12,18,23,25–27 These aneurysms usually involve the distal ACA adjacent to the falx (40%), involve the major vessels along the skull base (35%), or have a cortical location (25%).27–29 The child usually presents with a
Pediatric Cerebral Aneurysms hemorrhagic episode about 4 weeks after the initial injury; however, immediate bleeding has also been reported.30 Most children have sustained a closed head injury, but other causes include penetrating injuries and surgery.30,31
Infectious Aneurysms Infectious aneurysms account for 5% to 15% of pediatric aneurysms.11,18,26,32 They are most often of bacterial origin.33–35 The most common organism is staphylococcus, followed by streptococcus and other gram-negative organisms.24 Infectious arterial aneurysms are usually caused by bacterial
endocarditis in infants with congenital or rheumatic heart disease. Infections involving the sphenoid sinus or mastoid air cells and sinus thrombophlebitis may also involve the adjacent artery causing an infectious aneurysm.12,36,37 Infectious arterial aneurysms have also been observed in children with chronic mucocutaneous candidiasis and human immunodeficiency virusinfection.38–43
Saccular Aneurysms Saccular aneurysms are the most common type of aneurysm occurring in the pediatric population
Fig. 1. An 8-year-old girl who presented with worst headache of her life from a grade 3 Hunt and Hess SAH. (A) Lateral view of a selective internal carotid angiogram shows a posterior communicating artery (PCOM) aneurysm. (B) Final angiogram shows the aneurysm coiled to exclusion with preservation of the PCOM artery. (C) A 6-month follow-up angiogram shows persistent exclusion of the aneurysm with patent PCOM artery.
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Gemmete et al (between 46% and 70%).11,12,24,26 The cause of saccular aneurysms is unknown. They usually occur at bifurcation points of vessels, suggesting hemodynamic factors.10,21
Dissecting Aneurysms (Nontraumatic) Dissecting aneurysms in the pediatric population occur 4 times more often than in the adult population.11,12 This type of aneurysm can occur in the anterior or posterior circulation, especially the P1 and P2 segments of the posterior cerebral artery, supraclinoid ICA, and middle cerebral artery. Hetts
and colleagues,18 in the largest reported series, evaluated 77 patients with 103 intracranial aneurysms and showed a greater incidence of dissecting aneurysms in the anterior circulation. Lasjaunias and colleagues,11 in their series of 59 consecutive children with 79 aneurysms, showed an almost equal distribution between the anterior and posterior circulation. Agid and colleagues,12 in their series of 33 patients with 37 aneurysms, showed that most dissecting aneurysms involve the posterior circulation. There are reports of dissecting aneurysms in children healing spontaneously with occlusion of the parent artery.44
Fig. 2. A 4-year-old boy who presented with a headache from a grade 2 Hunt and Hess SAH. (A) Selective vertebral artery angiogram shows a left posterior cerebral artery (PCA) aneurysm. (B) Selective PCA angiogram shows the aneurysm at the P2/P3 segment. (C) Lateral spot fluoroscopic images shows the Histoacryl glue within the aneurysm and adjacent PCA segment. (D) Final vertebral angiogram confirming exclusion of the aneurysm with arterial collaterals supplying left PCA territory.
Pediatric Cerebral Aneurysms Giant Aneurysms
DIAGNOSIS
Giant aneurysms (>25 mm) in children are about 4 times more common than in adults.22,25,45–47 Their reported incidence in children is between 25% and 45%.48 Giant aneurysms should be considered in the dissection category. Children who have giant aneurysms often present with mass effect and only 35% of the time with SAH.12,18,49
For a child with suspected SAH, the diagnosis begins with a noncontrast computed tomography (CT) scan of the head. If this study is normal and the clinical history is strongly suspicious for SAH, then a lumbar puncture is required. The presence of xanthochromia or blood requires additional imaging in the form of a CT angiogram or a magnetic resonance (MR) angiogram of the circle of Willis. The choice of imaging modality is made on a case-by-case basis with an effort to reduce unnecessary radiation exposure while obtaining the necessary data to plan treatment and postoperative management. Digital subtraction angiography (DSA) is still the gold standard for the diagnosis of cerebral aneurysms. For patients with unruptured aneurysms who may present with headache, seizures, or mass effect, MR imaging of the brain with an MR angiogram of the circle of Willis is valuable to limit radiation exposure because these patients may need long-term follow-up imaging.
NATURAL HISTORY Given the pediatric patient’s lifespan, the cumulative risks of aneurysm growth, rupture, recurrence, de novo aneurysm formation, and retreatment are considerable, hence treatment and posttreatment follow-up are mandatory.
CLINICAL PRESENTATION Children with intracranial aneurysms can present with SAH, headache, direct compressive effects, focal neurologic deficits, or seizures.19 Sixty percent of children with SAH have a cerebral aneurysm.50 Fusiform aneurysms tend to present with nonhemorrhagic deficits.18 Many children with SAH present with a Hunt and Hess grade between 1 and 3.11,12,47,48,51 The reason for the better clinical grade at presentation is unclear, but this may be related to fewer comorbidities, a superior nitric oxide synthase pathway, or the robustness of the leptomeningeal arterial collaterals.11,52 In our series, 56% of patients presented with SAH, 33% with mass effect, and 11% after trauma.
TREATMENT In the past, aneurysms have been treated surgically, with either excision or clipping of the aneurysmal segment. In recent years there has been a shift toward the use of endovascular intervention with a strong desire to avoid open surgery in young children. A multidisciplinary team consisting of stroke neurologists, cerebrovascular neurosurgeons, and neurointerventional radiologists is
Fig. 3. A 9-month-old boy who presented with left-sided weakness. (A) Axial fluid-attenuated inversion recovery MR image of the brain shows a large flow void in the right M1 segment. (B) Three-dimensional time of flight MR angiogram shows a wide-necked saccular aneurysm involving the right M1 segment.
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Fig. 3. (C) Right internal carotid angiogram shows a wide-necked saccular aneurysm involving the right M1 segment. (D) Right internal carotid angiogram shows an enterprise stent from the distal right M1 segment across the neck of the aneurysm extending into the supraclinoid ICA with coils within the aneurysm. (E) Final right internal carotid angiogram after embolization shows filling at the base of the aneurysm with a small filling defect within the distal stent.
mandatory to treat complex intracranial aneurysms and achieve excellent results.53 Treatment options include observation, endovascular therapy, or surgical clipping. The treatment modality depends on location, vascular anatomy, and aneurysm shape. Surgical treatment includes direct clipping, clip reconstruction, and aneurysm trapping with or without bypass procedures. For endovascular treatment, we generally use a femoral approach, using a 4-Fr to 6-Fr access system. Cerebral angiography and aneurysm catheterization techniques are similar to those used in adults apart from the careful use of contrast
according to child size. Other specific issues related to small children include the careful monitoring of blood loss and fluid requirements. Simple coiling with or without adjuvant techniques such as balloon remodeling or stent placement are primarily used for most aneurysms (Fig. 1); however, glue is used for distal fusiform aneurysms (Fig. 2). Stents, including flow-diverting stents, may be necessary for fusiform and giant aneurysms (Fig. 3). In our series, 8 patients were treated with endovascular techniques, and 1 was managed conservatively, because risk of treatment was considered to outweigh the benefit. Endovascular techniques
Pediatric Cerebral Aneurysms included coil (n 5 5) or glue (n 5 1) embolization, stent coiling (n 5 1), and balloon occlusion (n 5 1).
OUTCOME In our series, 6 of the patients had an excellent outcome, 1 was left severely disabled, and 2 patients died. Of the 2 patients who died, 1 was managed conservatively, and the other rebled during the occlusion procedure. In the Toronto series, children treated by an endovascular approach had a better clinical outcome than those in the surgically treated group.12 Seventy-seven percent of the patients who received endovascular treatment made a good recovery (modified Rankin scale 0–1) compared with 44.4% of patients treated with open surgery. Lasjaunias and colleagues11 also reported good long-term results and outcome in their endovascular-treated aneurysms. Saraf and colleagues,54 in a study of 23 pediatric patients with intracranial aneurysms, showed an overall favorable outcome in 22 of 23 treated with endovascular techniques. A report from China of 22 patients with intracranial aneurysms treated by endovascular techniques showed a good outcome in 96% of patients with a Glasgow Outcome Scale of 4 or 5.55
SUMMARY Childhood intracranial aneurysms differ from those in the adult population in incidence and gender prevalence, cause, location, and clinical presentation. Endovascular treatment of pediatric aneurysms is the suggested approach because it offers both reconstructive and deconstructive techniques and a better clinical outcome compared with surgery; however, the long-term durability of endovascular treatment is still questionable, therefore long-term clinical and imaging follow-up is necessary.
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