Anterior odontoid screw fixation indications

Anterior odontoid screw fixation indications

Anterior odontoid screw fixation (AOSF) and posterior occipitocervical fusion are both well-accepted techniques for surgical treatment but with unique indications and contraindications as well as varied reported outcomes.

Joaquim et al. reviewed the literature about specific patients and fracture characteristics that may guide treatment toward one technique over the other. AOSF can preserve atlantoaxial motion, but requires a reduced odontoid, an intact transverse ligament, and a favorable fracture line to achieve adequate fracture compression. Additionally, older patients may have a higher rate of pseudarthrosis using this technique, as well as postoperative dysphagia. posterior occipitocervical fusion has a higher rate of fusion and is indicated in patients with severe atlantoaxial misalignment and with poor bone quality. posterior occipitocervical fusion allows direct open reduction of displaced fragments and can reduce any atlantoaxial instability. It is also used as a salvage procedure after failed AOSF. However, this technique results in loss of atlantoaxial motion, requires prone positioning, and demands a longer operative duration than AOSF, factors that can be a challenge in patients with severe medical conditions. Although both anterior and posterior approaches are acceptable, many clinical and radiological factors should be taken into account when choosing the best surgical approach. Surgeons must be prepared to perform both procedures to adequately treat these injuries 1)


Full-Endoscopic Anterior Odontoid Screw Fixation is a feasible and effective option for Odontoid fracture type II treatment. The procedure is less invasive than other techniques and provides clear direct visualization of the involved structures 2).


Direct anterior screw fixation is an effective and safe method for treating recent odontoid fractures (<6 months postinjury). It confers immediate stability, preserves C1-2 rotatory motion, and achieves a fusion rate that compares favorably with alternative treatment methods. In contradistinction, in patients with remote fractures (> or = 18 months postinjury), a significantly lower rate of fusion is found when using this technique, and these patients are believed to be poor candidates for this procedure 3).


Although anterior screw fixation is the ideal choice for type Ⅱ odontoid fractures with anterior superior to posterior inferior fracture line, it may not be the best choice for comminuted or fracture end hardened type Ⅱ odontoid fractures 4).


1)

Joaquim AF, Patel AA. Surgical treatment of Type II odontoid fractures: anterior odontoid screw fixation or posterior cervical instrumented fusion? Neurosurg Focus. 2015 Apr;38(4):E11. doi: 10.3171/2015.1.FOCUS14781. PMID: 25828487.
2)

Kotheeranurak V, Pholprajug P, Jitpakdee K, Pruttikul P, Chitragran R, Singhatanadgige W, Limthongkul W, Yingsakmongkol W, Kim JS. Full-Endoscopic Anterior Odontoid Screw Fixation: A Novel Surgical Technique. Orthop Surg. 2022 Apr 20. doi: 10.1111/os.13271. Epub ahead of print. PMID: 35445547.
3)

Apfelbaum RI, Lonser RR, Veres R, Casey A. Direct anterior screw fixation for recent and remote odontoid fractures. J Neurosurg. 2000 Oct;93(2 Suppl):227-36. PubMed PMID: 11012053.
4)

Yang S, Liu YJ, Jiang WM. Experience in surgery treatment of type Ⅱ odontoid fractures: A report of two cases and review of the literature. Chin J Traumatol. 2019 Nov 1. pii: S1008-1275(19)30333-5. doi: 10.1016/j.cjtee.2019.10.003. [Epub ahead of print] PubMed PMID: 31757743.

Anterior sacral meningocele in Marfan syndrome

Anterior sacral meningocele in Marfan syndrome

Twenty-four Marfan and 2 Loeys-Dietz patients had anterior sacral meningocele at follow-up, compared with 21 and 1, respectively, at baseline. Three Marfan patients developed herniation of a nerve root sleeve during follow-up. This was not seen in other individuals. The dural sac ended significantly lower at follow-up, and the dural sac ratio at level L5 was significantly increased from baseline in the Marfan patients.

In Marfan and Loeys-Dietz syndrome, dural ectasia may present or worsen during adulthood. The cut-off value of dural sac ratio at level S1 is suggested elevated to 0.64. The results from the present study may help as guidance for appropriate follow-up of patients with dural ectasia 1).

A case of a 46-year-old woman who presented with urinary incontinence, early satiety, and back pain in the setting of a known anterior sacral meningocele. Before operative management, the anterior sacral meningocele ruptured with the patient presenting signs and symptoms of intracranial hypotension. Conservative management did not alleviate the pain. She was ultimately managed with posterior sacroplasty followed by anterior sacral meningocele resection and placement of a lumboperitoneal shunt. The patient did not have reaccumulation of the meningocele or recurrent symptoms at the latest follow-up.

The progression of dural ectasia in Marfan syndrome to an anterior sacral meningocele is uncommon. It is important to identify the characteristics associated with an expanding dural ectasia as this patient’s symptoms progressed over time and the meningocele grew large. Given its rarity, there are no guidelines in place regarding size at which repair of an anterior sacral meningocele should occur prophylactically. It is important to review these cases in order continue to learn about progression, management, and outcomes of patients with an anterior sacral meningocele. 2).


A 43-year-old woman with a history of Marfan syndrome and a large ASM was referred for neurosurgical intervention. The ASM was filling the pelvic cavity and causing severe compression of the bladder. The patient underwent surgical decompression of the cyst through an anterior transabdominal approach and closure of the fistulous tract with a pedicled omental flap. This is the first reported case of successful closure of an ASM with an omental flap. At the 6-month follow-up, the ASM had not recurred on imaging and the patient’s symptoms had resolved. Anterior sacral meningoceles are rare lesions that often require neurosurgical intervention. Although most can be treated posteriorly, large ASMs compressing the abdominal or pelvic organs may require a transabdominal approach. Moreover, ASMs with wide dural stalks may benefit from closure with an omental flap. 3).


A 43-year-old man diagnosed with Marfan syndrome suffered sacrococcygeal trauma. He was admitted to the emergency room due to symptoms of headache, nausea, and lower limb subjective weakness. CT and MRI showed a large retroperitoneal mass with hemorrhagic content close to the sacrum. Likewise, the MRI showed an image compatible with subarachnoid hemorrhage in the thoracic spinal area, cerebral convexity, and the basal cisterns. The patient went into surgery for an anterior abdominal approach in the midline to reduce the content of the lesion, and subsequently, in the same act, a posterior approach was done with an S1-S2 laminectomy and obliteration of the pedicle. Postoperative MRI 5 months later showed resolution of the ASM.

Anterior sacral meningocele is characterized by herniation of the dura mater and the arachnoid mater outside the spinal canal through a defect of the sacrum. We add the risk of bleeding after trauma-never seen in the literature-as one of the possible inherent complications of this lesion.

This report highlights a complication never seen in the literature of a relatively rare condition. In our case, the combined approach was effective for both clinical control and lesion regression. 4).


A patient with Marfan’s syndrome and ASMs who was referred to gynaecology owing to dysmenorrhoea and left-sided pelvic pain radiating to the left leg. A transvaginal ultrasound scan (TVUS) detected a left pelvic cystic tubular structure, attributed to a hydrosalpinx, which, in retrospect, likely corresponded to the ASM. The patient went on to have TVUS-guided drainage of this cystic structure, resulting in an ASM abscess. It is difficult to distinguish ASM from the vastly more common hydrosalpinx using TVUS alone, and in patients with an atypical appearing posteriorly positioned cystic pelvic lesion or in the presence of underlying conditions known to be associated with ASMs, MRI should be considered before any interventional procedure to drain the suspected hydrosalpinx transvaginally. The patient was successfully treated using a minimally invasive CT-guided posterior trans-sacral drainage technique. 5).


A 20-year old female with Marfan syndrome who presented with abdominal distention that was misdiagnosed as an ovarian cyst on pelvic ultrasound. Pelvic magnetic resonance (MR) imaging showed large, well-defined multiloculated intrasacral and presacral cysts communicating via two separate broad necks and extending through defects in anterior aspect of sacral vertebrae. This case emphasizes that anterior sacral meningocele should be considered in the differential diagnosis of cases with pelvic cysts particularly in patients with underlying connective tissue disorders. Because severe neurologic complications or even death may occur without proper preoperative planning in such cases, MR imaging should always be performed for evaluation and characterization of pelvis cystic lesions. 6).


A young woman with Marfan syndrome who was being treated with anticoagulants for a prosthetic heart valve and who presented with a spontaneous retroperitoneal hemorrhage requiring surgical evacuation. No CSF leak was encountered at surgery, but she developed progressively more severe positional headaches over the following year. She then experienced the sudden onset of acute urinary obstruction, at which time CT revealed a 17 × 15 × 13-cm presacral pseudomeningocele communicating with the thecal sac through a sacral bone defect. An anterior surgical approach was used for drainage of the pseudomeningocele as well as for primary closure of the dural defect with a bovine pericardial patch and autologous subcutaneous fat graft. After a short period of lumbar subarachnoid drainage of the CSF, the patient was able to resume normal activity without recurrent symptoms. To the authors’ knowledge, such a pseudomeningocele in a patient with Marfan syndrome has been reported only twice, and this case features the largest pseudomeningocele to date. They also review the pertinent literature regarding presentation, diagnosis, and management of these lesions. 7).


Relapse of Escherichia coli meningitidis due to sacral meningocele in Marfan syndrome, treated only with antibiotherapy 8).


Surgical Treatment of Anterior Sacral Meningoceles in Patients with Marfan Syndrome: A Report of Three Cases 9).


A case of bacterial meningitis secondary to fistulous communication between a sacral meningocele and sigmoid colon in the setting of diverticulitis 10).


Five women who underwent laparoscopic transperitoneal surgery were clinically, radiologically, and surgically evaluated.

Result: All 5 patients underwent laparoscopic transperitoneal surgery and showed satisfactory results. They had no major complications. Three patients had headaches as minor complications, but it was gone in at most 3 days. Decrease in operative time, blood loss, and length of hospitalization were the advantages of the procedure.

The laparoscopic approach to treating anterior sacral meningocele was feasible and safe, with only minor complications. 11).


A woman with Marfan’s syndrome presenting with a clinical picture of acute gastroenteritis in whom severe bilateral hydroureteronephrosis associated to a neurogenic bladder and a giant anterior sacral meningocele was diagnosed incidentally. The importance of this case lies in the fact that the patient was asymptomatic despite the significant visceral repercussions already occurring that led to questioning of whether MRI follow-up would still be advisable even in the absence of symptoms. 12).


A 46-year-old woman with Marfan’s syndrome exhibiting an incomplete Currarino triad and recurrent bacterial meningitis which recurred three times in about six months. An anterior sacral meningocele (ASM) was noted in a lumbar MRI, and multiple bone defects in the sacrum were noted in 3D-CT. Surgical approach to prevent the recurrence of infection was limited to plasty for the meningocele, but no meningitis has been observed for two years. Radical surgery should be considered in cases with ASM who recurred bacterial meningitis. 13).


A 52 year old woman with Marfan syndrome who presented with a significantly large anterior sacral meningocele without having associated symptoms. In light of this case, we recommend that asymptomatic Marfan patients with dural ectasia should be closely observed without need for immediate surgical intervention 14).


18-year-old man with Marfan syndrome, diagnosed upon MRI morphological evaluation which showed a huge cystic mass in the pelvic space. Surgical excision even if curative was not performed in consideration of a stationary picture after one year since diagnosis. 15).


Two cases presenting as nongynaecological pelvic masses are described highlighting the clinical difficulty in diagnosis and the classical radiological findings 16).


Anterior sacral meningocele presenting as a pelvic/abdominal mass in a patient with Marfan syndrome 17).


The first case of a giant anterior sacral meeningocele rapidly cured by a simple endoscopic procedure 18). The postoperative course of the patient was characterized by immediate disappearance of the preoperative clinical signs. Computed tomographic scans demonstrated progressive complete collapse of the anterior sacral meningocele and partial resolution of the intrasacral component 19).


A marfanoid patient underwent celiotomy for a pelvic mass and was found to have an anterior sacral meningocele. Nine years prior to that time she had undergone surgery because of a “sacrococcygeal cyst,” which in retrospect seemed to be a posterior meningocele 20).


Purulent meningitis from surgical inoculation of an anterior sacral meningocele 21).


Anterior sacral meningocele in association with Marfan’s syndrome 22).


1)

Böker T, Vanem TT, Pripp AH, Rand-Hendriksen S, Paus B, Smith HJ, Lundby R. Dural ectasia in Marfan syndrome and other hereditary connective tissue disorders: a 10-year follow-up study. Spine J. 2019 Aug;19(8):1412-1421. doi: 10.1016/j.spinee.2019.04.010. Epub 2019 Apr 15. PMID: 30998996.
2)

Hollenberg AM, Baldwin AL, Mesfin A, Silberstein H. Rupture of Giant Anterior Sacral Meningocele in a Patient with Marfan Syndrome: Diagnosis and Management. World Neurosurg. 2018 Nov;119:137-141. doi: 10.1016/j.wneu.2018.07.249. Epub 2018 Aug 6. PMID: 30092475.
3)

Paisan GM, Crandall KM, Chen S, Burks SS, Sands LR, Levi AD. Closure of a giant anterior sacral meningocele with an omental flap in a patient with Marfan syndrome: case report. J Neurosurg Spine. 2018 Aug;29(2):182-186. doi: 10.3171/2018.1.SPINE171303. Epub 2018 May 25. PMID: 29799321.
4)

Gilete-Tejero IJ, Ortega-Martínez M, Mata-Gómez J, Rico-Cotelo M, Bernal- García LM, Yerga-Lorenzana B, Casado-Naranjo I. Anterior sacral meningocele presenting as intracystic bleeding. Eur Spine J. 2018 Jul;27(Suppl 3):276-280. doi: 10.1007/s00586-017-5128-1. Epub 2017 May 18. PMID: 28523383.
5)

Jawad S, Ejindu V, Johnson D, Shah MA, Abbasi MA, Ojha K, Papadakos N. Transvaginal ultrasound-guided aspiration of an anterior sacral meningocele masquerading as a hydrosalpinx, resulting in abscess formation. BJR Case Rep. 2016 Sep 3;3(1):20160037. doi: 10.1259/bjrcr.20160037. PMID: 30363340; PMCID: PMC6159307.
6)

Sahin N, Genc M, Kasap E, Solak A, Korkut B, Yilmaz E. Anterior Sacral Meningocele Masquerading as an Ovarian Cyst: A Rare Clinical Presentation Associated with Marfan Syndrome. Clin Pract. 2015 Apr 24;5(2):752. doi: 10.4081/cp.2015.752. PMID: 26236457; PMCID: PMC4500879.
7)

Stone JG, Bergmann LL, Takamori R, Donovan DJ. Giant pseudomeningocele causing urinary obstruction in a patient with Marfan syndrome. J Neurosurg Spine. 2015 Jul;23(1):77-80. doi: 10.3171/2014.11.SPINE131086. Epub 2015 Apr 24. PMID: 25909269.
8)

Bigaré M, Lesaffre X, Delassus JL, Bakir R, Bouldouyre MA. Rechute de méningite à Escherichia coli due à un méningocèle sacré dans le cadre d’une maladie de Marfan, traitée par antibiothérapie prolongée seule [Relapse of Escherichia coli meningitidis due to sacral meningocele in Marfan syndrome, treated only with antibiotherapy]. Presse Med. 2014 Jan;43(1):93-5. French. doi: 10.1016/j.lpm.2013.02.330. Epub 2013 Jul 19. PMID: 23876649.
9)

Ebnet J, Krauss JK, Lorenz M, Bektas H, Nakamura M. Surgical Treatment of Anterior Sacral Meningoceles in Patients with Marfan Syndrome: A Report of Three Cases. JBJS Case Connect. 2012 Apr-Jun;2(2):e16. doi: 10.2106/JBJS.CC.K.00040. PMID: 29252417.
10)

Samet JD, Johnson PT, Horton KM, Fishman EK. Diverticulitis complicated by fistulous communication of sigmoid colon with anterior sacral meningocele in a patient with Marfan syndrome. Radiol Case Rep. 2015 Dec 7;7(1):442. doi: 10.2484/rcr.v7i1.442. PMID: 27326266; PMCID: PMC4899866.
11)

Trapp C, Farage L, Clatterbuck RE, Romero FR, Rais-Bahrami S, Long DM, Kavoussi LR. Laparoscopic treatment of anterior sacral meningocele. Surg Neurol. 2007 Oct;68(4):443-8; discussion 448. doi: 10.1016/j.surneu.2006.11.067. PMID: 17905071.
12)

Santana JM, Gómez A, Alemán P, Travieso MM. Ureterohidronefrosis severa asociada a meningocele sacro anterior gigante asintomático: presentación de un caso y revisión de la literatura [Severe hydroureteronephrosis associated to asymptomatic giant anterior sacral meningocele: a case report and review of the literature]. Radiologia. 2007 Jan-Feb;49(1):43-6. Spanish. doi: 10.1016/s0033-8338(07)73715-3. PMID: 17397621.
13)

Hatano A, Akiyama K, Nagayama M, Takagi S. [Case of Marfan’s syndrome with anterior sacral meningocele along with recurring bacterial meningitis]. Rinsho Shinkeigaku. 2006 Sep;46(9):658-60. Japanese. PMID: 17260811.
14)

Nallamshetty L, Ahn NU, Ahn UM, Nallamshetty HS, Rose PS, Buchowski JM, Sponseller PD. Dural ectasia and back pain: review of the literature and case report. J Spinal Disord Tech. 2002 Aug;15(4):326-9. doi: 10.1097/00024720-200208000-00012. PMID: 12177551.
15)

Rigante D, Segni G. Anterior sacral meningocele in a patient with Marfan syndrome. Clin Neuropathol. 2001 Mar-Apr;20(2):70-2. PMID: 11327300.
16)

Voyvodic F, Scroop R, Sanders RR. Anterior sacral meningocele as a pelvic complication of Marfan syndrome. Aust N Z J Obstet Gynaecol. 1999 May;39(2):262-5. doi: 10.1111/j.1479-828x.1999.tb03390.x. PMID: 10755797.
17)

Schneider MB, Dittmar S, Boxer RA. Anterior sacral meningocele presenting as a pelvic/abdominal mass in a patient with Marfan syndrome. J Adolesc Health. 1993 Jun;14(4):325-8. doi: 10.1016/1054-139x(93)90182-o. PMID: 8347646.
18)

Raftopoulos C, Delecluse F, Braude P, Rodesh C, Brotchi J. Anterior sacral meningocele and Marfan syndrome: a review. Acta Chir Belg. 1993 Jan- Feb;93(1):1-7. PMID: 8470436.
19)

Raftopoulos C, Pierard GE, Rétif C, Braude P, Brotchi J. Endoscopic cure of a giant sacral meningocele associated with Marfan’s syndrome: case report. Neurosurgery. 1992 May;30(5):765-8. doi: 10.1097/00006123-199205000-00020. PMID: 1584392.
20)

Barter JF, Addison WA, Rosenberg ER, Hammond CB. Anterior sacral meningocele presenting as a pelvic mass and diagnosed only at celiotomy after an extensive workup. A case report. J Reprod Med. 1983 Oct;28(10):684-6. PMID: 6655630.
21)

le Mercier Y, Decazes JM, Mechali D, Redondo A, Aboulker J, Coulaud JP. Méningite purulente par inoculation chirurgicale d’une méningocèle sacrée antérieure. Une complication rare de la maladie de Marfan [Purulent meningitis from surgical inoculation of an anterior sacral meningocele: a rare complication of Marfan’s disease (author’s transl)]. Ann Med Interne (Paris). 1980;131(5):289-90. French. PMID: 7004305.
22)

Strand RD, Eisenberg HM. Anterior sacral meningocele in association with Marfan’s syndrome. Radiology. 1971 Jun;99(3):653-4. doi: 10.1148/99.3.653. PMID: 5578713.

Unruptured anterior communicating artery aneurysm rupture risk

Unruptured anterior communicating artery aneurysm rupture risk

Although the research on the risk factors of anterior communicating artery aneurysm has made great progress, the independent effect of each risk factor on the rupture of AComA aneurysm is controversial among different studies. For this answer Xie et al. will present the results employing the random effects model. Quality assessment of the included studies will be evaluated using the Newcastle–Ottawa Scale. Statistical analyses will be performed using Stata16 (Stata Corporation, College Station, TX, USA) software.The findings of this study will be submitted to peer-reviewed journals for publication. This systematic review will provide evidence to determine the risk factors that affect the rupture of the AComA aneurysm and quantify their independent effects 1).


Ma et al. found that larger size, greater size ratio, larger flow angle, irregular shape, and smoking of the patient were associated with the rupture of ACoA aneurysms based on univariate analysis. Size ratio (OR = 3.890, P = 0.003), irregular shape (OR = 1.068, P = 0.001), flow angle (OR = 1.054, P = 0.001), and current smoking (OR = 4.435, P = 0.009) were the strongest factors related to ruptured ACoA aneurysms based on multivariate logistic regression analysis. The areas under the curves for the flow angle and size ratio were 0.742 (95% CI 0.646-0.838; P = 0.001) and 0.736 (95% CI 0.621-0.796; P = 0.001), respectively. The strongest risk factors for rupture include size ratio, irregular shape, flow angle, and current smoking. These features should be taken into consideration to aid in the prediction of the rupture risk of ACoA aneurysms 2).


Multiple logistic regression model revealed that A1 dominance [odds ratio (OR) 3.034], an irregular shape (OR 3.358), and an aspect ratio ≥1.19 (AR; OR 3.163) increased the risk of rupture, while cerebral atherosclerosis (OR 0.080), and mean diameters ≥2.48 mm (OR 0.474) were negatively correlated with ACoAA rupture. Incorporating these five factors, the ROC analysis revealed that the threshold value of the multifactors was one, the sensitivity was 88.3%, and the specificity was 66.0%. The scoring model is a simple method that is based on A1 dominance, irregular shape, aspect ratio, cerebral atherosclerosis, and mean diameters from CTA and is of great value in the prediction of the rupture risk of ACoAAs 3).


According to the International Study of Unruptured Intracranial Aneurysms (ISUIA), anterior circulation (AC) aneurysms of <7 mm in diameter have a minimal risk of rupture. It is general experience, however, that anterior communicating artery (AcoA) aneurysms are frequent and mostly rupture at <7 mm. Bijlenga et al. found that AC aneurysms are not a homogenous group. Aneurysms between 4 and 7 mm located in AcoA or distal anterior cerebral artery present similar rupture odds to posterior circulation aneurysms. Intervention should be recommended for this high-risk lesion group 4).


For Matsukawa et al. the anterior projection of an ACoA aneurysm may be related to rupturing. The authors would perhaps recommend treatment to patients with unruptured ACoA aneurysms that have an anterior dome projection, a bleb(s), and a size ≥ 5 mm 5).


Aneurysms found unruptured in the ACoA show a risk of rupture twice as high as that of other intracranial aneurysms (95% confidence interval, 1.29-3.12). It is the first time this fact has been demonstrated based on the follow-up of unruptured aneurysms.

When deciding whether to operate on UIAs located in the ACoA, surgeons should consider their higher risk of rupture 6).


1)

Xie Y, Tian H, Xiang B, Li D, Liu YZ, Xiang H. Risk factors for anterior communicating artery aneurysm rupture: A protocol for systematic review and meta-analysis. Medicine (Baltimore). 2021 Dec 3;100(48):e28088. doi: 10.1097/MD.0000000000028088. PMID: 35049234.
2)

Ma X, Yang Y, Liu D, Zhou Y, Jia W. Demographic and morphological characteristics associated with rupture status of anterior communicating artery aneurysms. Neurosurg Rev. 2020 Apr;43(2):589-595. doi: 10.1007/s10143-019-01080-w. Epub 2019 Jan 31. PMID: 30706157.
3)

Wang GX, Wang S, Liu LL, Gong MF, Zhang D, Yang CY, Wen L. A Simple Scoring Model for Prediction of Rupture Risk of Anterior Communicating Artery Aneurysms. Front Neurol. 2019 May 31;10:520. doi: 10.3389/fneur.2019.00520. PMID: 31214103; PMCID: PMC6554323.
4)

Bijlenga P, Ebeling C, Jaegersberg M, Summers P, Rogers A, Waterworth A, Iavindrasana J, Macho J, Pereira VM, Bukovics P, Vivas E, Sturkenboom MC, Wright J, Friedrich CM, Frangi A, Byrne J, Schaller K, Rufenacht D; @neurIST Investigators. Risk of rupture of small anterior communicating artery aneurysms is similar to posterior circulation aneurysms. Stroke. 2013 Nov;44(11):3018-26. doi: 10.1161/STROKEAHA.113.001667. Epub 2013 Jul 30. PMID: 23899912.
5)

Matsukawa H, Uemura A, Fujii M, Kamo M, Takahashi O, Sumiyoshi S. Morphological and clinical risk factors for the rupture of anterior communicating artery aneurysms. J Neurosurg. 2013 May;118(5):978-83. doi: 10.3171/2012.11.JNS121210. Epub 2012 Dec 14. PMID: 23240701.
6)

Mira JM, Costa FA, Horta BL, Fabião OM. Risk of rupture in unruptured anterior communicating artery aneurysms: meta-analysis of natural history studies. Surg Neurol. 2006;66 Suppl 3:S12-9; discussion S19. doi: 10.1016/j.surneu.2006.06.025. PMID: 17081844.
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