Cerebral aneurysm

from Wikipedia, the free encyclopedia
Classification according to ICD-10
I67.1 Cerebral aneurysm
ICD-10 online (WHO version 2019)

A cerebral (also intracranial) aneurysm is a pathologically permanent enlargement of the cross-section or a balloon-shaped bulging of a cerebral artery. A rupture can occur, resulting in uncontrolled bleeding in the brain . A rupture occurs on average in around 1% of aneurysms per year and can be fatal.

Classification

Cerebral aneurysms are divided based on their location , size, and morphology .

Scheme of a cerebral aneurysm.

Cerebral aneurysms occur within the skull , where they are classified based on the location of the artery , such as the internal carotid artery . Most aneurysms occur at the cerebral arterial circuit . 95% of them occur in the anterior arterial circulation and only 5% in the posterior circulation.

Cerebral aneurysms are classified based on their size . To do this, their diameter is determined. Aneurysms with a diameter smaller than 2 mm are called microaneurysms . Aneurysms with a diameter larger than 25 mm are called giant aneurysms .

Cerebral aneurysms are divided into the following types based on their morphology :

  • Saccular aneurysms are characterized by a balloon-shaped bulge on an artery.
  • Fusiform aneurysms are locally widened vessels with a maximum vessel diameter in the middle that decreases on both sides.
  • Dissecting aneurysms are vasodilatation due to the splintering of the wall layers of the blood vessel. Blood gets between the inner and outer vessel wall.

Saccular aneurysms are the most common form of cerebral aneurysms, accounting for about 91%, followed by fusiform aneurysms, accounting for about 6%.

distribution

The normalized disease frequency ( prevalence ) is between 3% and 7%. Cerebral aneurysms are more common in people over 40 years of age. Women are affected more often than men in a ratio of 5: 3. Descendants of first-degree relatives who have found aneurysms have a three to four times higher prevalence of aneurysm than the general population.

root cause

Cerebral aneurysms are not congenital; they develop over the course of life. The cause of the development of cerebral aneurysms is unclear. For example, a congenital weakness of the cells of the inner vessel wall, the so-called endothelial cells, is discussed . In the course of life, under certain circumstances, such as B. Long-standing high blood pressure , an aneurysm. Influenceable ( exogenous ) factors that favor the development are smoking or alcohol abuse . The very rare cyst kidney also favors its development. A study published in 2010 also documents a significantly increased risk of brain aneurysms in patients with aorta bicuspid, a relatively common congenital malformation of the aortic valve . It is known that headbanging increases the number of cases with arterial dilation of the vertebral artery .

Pathophysiology

One theory of aneurysm formation is the appearance of a weak point in the vessel wall. This is caused by the steady impact of blood flow on a small area. Over time, the weak point enlarges and an aneurysm forms. The increasing area increases the tension on the vessel wall. This tension causes a complex inflammatory response and leads to the formation of aneurysms.

There are approaches that attempt to link hemodynamic properties to the rupture of aneurysms. For example, a compound of has the wall shear stress (engl. Wall-shear stress ) and examined rupture rate. Conflicting results have been presented so far.

Clinical manifestations

Unruptured cerebral aneurysms rarely cause symptoms . Symptoms usually occur when larger aneurysms compress neurons . It can e.g. B. visual disturbances , pain and dizziness occur. Larger aneurysms are more often symptomatic.

A ruptured aneurysm leads to an uncontrolled discharge of blood in the brain region ( subarachnoid hemorrhage ). This can lead to an annihilating headache , fainting, and neck stiffness .

Risk of rupture

The main danger of a cerebral aneurysm is the development of a tear (rupture) with consequent subarachnoid hemorrhage. It is not known if and when such a rupture occurs. But you can give an estimate of how high the risk of a rupture is. Clinical studies show that it depends on the size and position of the aneurysm. Microaneurysms with a diameter of less than 3 mm have an immeasurable risk of rupture. Small aneurysms with a diameter of less than 7 mm have a risk of rupture of less than 1% per year and also grow slowly. An estimate of the rupture risk of 5% per 5 years is clinically appropriate.

Investigation methods

Cerebral aneurysms are diagnosed through angiography . This is a specialized radiological representation of vessels using diagnostic imaging methods such as X-rays or magnetic resonance tomography .

Representation of an aneurysm in a digital subtraction angiography.
Representation of a microaneurysm in a CT angiography.

The following angiographies are used for diagnosis:

The different types of angiography are well suited to detect aneurysms. One measures the sensitivity , i.e. how many known aneurysms were found with one type of angiography. Digital subtraction angiography has the best sensitivity with almost 100%, which is why it is used as the gold standard . With CT angiography the sensitivity is 90%, with MR angiography 87%. The transcranial Doppler examination has the lowest sensitivity with 82%.

Other factors that influence aneurysm detection include the size of the aneurysm, image quality, and the experience of the radiologist. Microaneurysms with a diameter of less than 2 mm are difficult to detect with imaging methods.

If an aneurysm has already ruptured and has triggered cerebral hemorrhage, this can be determined by means of a computed tomography or lumbar puncture .

With the increasing use of imaging techniques, incidental findings of (asymptomatic) aneurysms have also become more common.

treatment

Ruptured aneurysms must be treated immediately to stop the bleeding in the brain. There is no obligation to treat unruptured aneurysms. There are two therapies for treating ruptured aneurysms: endovascular and neurosurgical . There is also conservative therapy for the treatment of unruptured aneurysms .

Treatment of an aneurysm with the coiling method. In the upper part of the picture a CT angiography can be seen, in the lower part a digital subtraction angiography. The coil can be seen in the lower part of the picture (center).

In endovascular therapy , so-called coils (spirals made of a platinum alloy) are brought into the aneurysm sac by means of a hollow micro -catheter via the inguinal artery . These coils only fill the aneurysm to about 10% to 30%, but cause thrombus formation and thus prevent further blood circulation in the aneurysm and thus a rupture. One advantage of the procedure is that no open brain surgery has to be performed.

Treatment of an aneurysm with clipping.

In neurosurgical therapy , the aneurysm is treated with a craniotomy (open brain surgery). The aneurysm sac is clamped off with a clip. Thus the aneurysm is excluded from the bloodstream. Successful clipping can be confirmed by angiography. Alternatively, stents can also be used to strengthen the arterial wall or to change the flow properties and thus promote thrombosis.

In conservative therapy , no intervention is made; instead, the aneurysm is monitored by regular angiography. This is an option, especially for small, non-symptomatic aneurysms because of the low risk of rupture.

With either treatment, there is a risk that cerebral hemorrhage will recur. There is no consensus on whether endovascular or neurosurgical therapy has a better prognosis because the mortality rate is similar.

Statistically, the mortality rate is lower with conservative therapy (see risk of rupture ) than with surgery. However, this is not yet clinically accepted, since the vast majority of known aneurysms are treated. Factors such as good patient education and the perception of the aneurysm as a ticking time bomb also play a role.

In general, the prognosis for a ruptured aneurysm depends on the size, location and state of health. The mortality is about 50%, with 46% of the survivors suffering permanent (brain) damage.

literature

Web links

Commons : Aneurysm  - collection of images, videos and audio files
Wiktionary: aneurysm  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ a b c d e M. H. Vlak, A. Algra, R. Brandenburg, GJ Rinkel: Prevalence of unruptured intracranial aneurysms, with emphasis on sex, age, comorbidity, country, and time period: a systematic review and meta-analysis . In: The Lancet Neurology . 10, No. 7, July 2011, pp. 626-636. doi : 10.1016 / S1474-4422 (11) 70109-0 . PMID 21641282 .
  2. ^ T. Inagawa: Surgical treatment of multiple intracranial aneurysms . In: Acta neurochirurgica . 108, No. 1-2, January 1991, pp. 22-29. doi : 10.1007 / BF01407662 .
  3. ↑ Li M, Chen S, Li Y, Chen Y, Cheng Y, Hu D, et al .: Prevalence of Unruptured Cerebral Aneurysms in Chinese Adults Aged 35 to 75 Years: A Cross-sectional Study . In: Ann Intern Med. . 159, No. 8, October 2013, pp. 514-21. doi : 10.7326 / 0003-4819-159-8-201310150-00004 . PMID 24126645 .
  4. ↑ a b c d e f g Michael Forsting, C. Cognard, M. Knaut, Isabel Wanke, A. Dörfler, M. Forsting, W. Küker, L. Pierot, L. Spelle, I. Szikora, I. Wanke: 5 Intracranial aneurysms . In: Intracranial Vascular Malformations and Aneurysms: From Diagnostic Work-Up to Endovascular Therapy . Springer, November 4, 2008, ISBN 978-3-540-32920-6 , pp. 167-283.
  5. ↑ Wouter I. Schievink, S. Sharo, M. Raissi, Marcel Maya, Arlys Velebir: Screening for intracranial aneurysms in patients with bicuspid aortic valve . In: Neurology . 74, No. 18, May 4, 2010, pp. 1430-1433. doi : 10.1212 / WNL.0b013e3181dc1acf .
  6. ↑ MR Egnor, LK Page, C. David: Vertebral artery aneurysm - a unique hazard of head banging by heavy metal rockers. Case report . In: Pediatr Neurosurg . 17, No. 3, 1991, pp. 135-138. doi : 10.1159 / 000120583 . PMID 1819327 .
  7. ↑ Catherine Haberland: Clinical neuropathology: text and color atlas . Demos, New York 2007, ISBN 978-1-888799-97-2 , pp. 70 .
  8. ↑ Nohra Chalouhi, Brian L Loh, David Hasan: Review of Cerebral Aneurysm Formation, Growth, and Rupture . In: American Heart Association Journal . 44, November 25, 2013, pp. 3613-3622. doi : 10.1161 / STROKEAHA.113.002390 .
  9. ↑ H Meng, VM Tutino, J Xiang, A Siddiqui: High WSS or Low WSS? Complex Interactions of Hemodynamics with Intracranial Aneurysm Initiation, Growth, and Rupture: Toward a Unifying Hypothesis . In: American Journal of Neuroradiology . 35, No. 7, July 2014, pp. 1254-1262. doi : 10.3174 / ajnr.A3558 .
  10. ↑ a b A Malhotra, Wu X, Forman HP, Grossetta Nardini HK, Matouk CC, Gandhi D, Moore C, Sanelli P: Growth and Rupture Risk of Small Unruptured Intracranial Aneurysms: A Systematic Review . In: Ann. Intern. Med. . 167, No. 1, July 2017, pp. 26–33. doi : 10.7326 / M17-0246 . PMID 28586893 .
  11. ↑ JP Greving, Wermer MJ, Brown RD Jr, Morita A, Juvela S, Yonekura M, Ishibashi T, Torner JC, Nakayama T, Rinkel GJ, Algra A: Development of the PHASES score for prediction of risk of rupture of intracranial aneurysms: a pooled analysis of six prospective cohort studies . In: Lancet Neurology . 13, No. 1, January 2014, pp. 59-66. doi : 10.1016 / S1474-4422 (13) 70263-1 . PMID 24290159 .
  12. ↑ a b J. Fiehler: Unruptured intracranial aneurysms: when to look, when to treat? . In: RöFo - Advances in the field of X-rays and imaging processes . 184, No. 2, 2012, pp. 97-104. doi : 10.1055 / s-0031-1281984 .
  13. ^ PM White, JM Wardlaw, V Easton: Can noninvasive imaging accurately depict intracranial aneurysms? A systematic review . In: Radiology . 217, No. 2, 2000, pp. 361-370. doi : 10.1148 / radiology.217.2.r00nv06361 .
  14. ^ T Neumann-Haefelin: The incident aneurysm: When to treat - when to wait? . In: Journal of Neurology, Neurosurgery and Psychiatry . 12, No. 2, 2011, pp. 148–151.
  15. ↑ G. Guglielmi, F. Viñuela, G. Duckwiler, J. Dion, P. Lylyk, A. Berenstein, C. Strother, V. Graves, V. Halbach, D. Nichols: Endovascular treatment of posterior circulation aneurysms by using electrothrombosis electrically detachable coils . In: Journal of neurosurgery . 77, No. 4, October 1992, pp. 515-524. doi : 10.3171 / jns.1992.77.4.0515 . PMID 1527608 .
  16. ^ HG Morales, M. Kim, EE Vivas, MC Villa-Uriol, I. Larrabide, T. Sola, L. Guimaraens, AF Frangi: How do coil configuration and packing density influence intra-aneurysmal hemodynamics? . In: AJNR. American journal of neuroradiology . 32, No. 10, pp. 1935-1941. doi : 10.3174 / ajnr.A2635 . PMID 21885712 .
  17. ^ Solomon RA, Fink ME, Pile-Spellman J.: Surgical management of unruptured intracranial aneurysms . In: Journal of neurosurgery . 80, No. 3, March 1994, pp. 440-446. doi : 10.3171 / jns.1994.80.3.0440 . PMID 8113856 .
  18. ↑ JV Byrne, R. Beltechi, JA Yarnold, J. Birks, M. Kamran: Early experience in the treatment of intra-cranial aneurysms by endovascular flow diversion: a multicentre prospective study . In: PloS one . 5, No. 9, 2010, pp. 440-446. doi : 10.1371 / journal.pone.0012492 . PMID 20824070 .
  19. ↑ M. Sonobe, T. Yamazaki, M. Yonekura, H. Kikuchi: Small unruptured intracranial aneurysm verification study: SUAVe study, Japan . In: Stroke . 41, No. 9, September 2010, pp. 1969-1977. doi : 10.1161 / STROKEAHA.110.585059 . PMID 20671254 .
  20. ^ PV Raja, Huang, J, Germanwala, AV, Gailloud, P, Murphy, KP, Tamargo, RJ: Microsurgical clipping and endovascular coiling of intracranial aneurysms: a critical review of the literature. . In: Neurosurgery . 62, No. 6, June 2008, pp. 1187-202; discussion 1202-3. doi : 10.1227 / 01.new.0000333291.67362.0b . PMID 18824986 .
  21. ↑ A. Molyneux, R. Kerr, L. Yu, M. Clarke, M. Sneade, J. Yarnold, P. Sandercock, and Others. International subarachnoid aneurysm trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomized comparison of effects on survival, dependency, seizures, rebleeding, subgroups. The Lancet, 366 (9488): 809-817, 2005
  22. ↑ Brain aneurysms: clipping or coiling for bleeding? Retrieved July 26, 2019 .
  23. ↑ J. van Gijn, RS Kerr, and GJE Rinkel. Subarachnoid haemorrhage. Lancet, 369 (9558): 306-18, January 2007
  24. ↑ JI Suarez, RW Tarr, and WR Selman. Aneurysmal subarachnoid hemorrhage. The New England journal of medicine, 354 (4): 387-96, January 2006.