Aneurysmatic subarachnoidal haemorrhage: Incidence and location of small ruptured cerebral aneurysms – a retrospective population-based study

ZusammenfassungEINLEITUNG: Ziel der vorliegenden retrospektiven Studie war eine Analyse der Inzidenz von Subarachnoidealblutungen aus kleinen (bis 5 mm Durchmesser) cerebralen Aneurysmen, sowie der Aneurysmenlokalisation in einer konsekutiven Patientenserie, die im Bundesland Vorarlberg/Österreich neurochirurgisch behandelt wurde. METHODEN: Insgesamt wurden innerhalb der letzten vier Jahre 82 Patienten nach spontaner Subarachnoidealblutung (Durchschnittsalter 53,7 Jahre, range 21–84 Jahre, 47 Frauen und 35 Männer) an der Neurochirurgischen Abteilung des Akademischen Lehrkrankenhauses Feldkirch, die zuständig ist für alle 360.000 Einwohner des Bundeslandes (entsprechend einer jährlichen Subarachnoidealblutungsinzidenz von 5,7/100.000), behandelt. Bei 70 Patienten (85,4 %) wurde ein cerebrales Aneurysma mit Computertomographie Angiographie und/oder digitaler cerebraler Angiographie diagnostiziert. Von diesen wurden 47 Patienten (66,2 %, Durchschnittsalter 52,1 Jahre, von 24–77 Jahren) neurochirurgisch mit Aneurysmenklippung behandelt und in die Studie inkludiert. Präoperativ wurden Computertomographien, Computertomographie Angiographien und digitale cerebrale Angiographien nach Blutmenge, Aneurysmengröße und –lokalisation untersucht. Der klinische Zustand der Patienten wurde zum Zeitpunkt der Aufnahme nach der Hunt and Hess Klassifikation und bei Entlassung nach der Glasgow Outcome Scale eingeteilt. ERGEBNISSE: Entsprechend der Koivisto Kategorien waren 18 Aneurysmen an der Arteria cerbri anterior, 17 Aneurysmen an der Arteria cerebri media, 11 an der Arteria carotis interna und 1 im vertebrobasilären Stromgebiet. Der durchschnittliche Aneurysmendurchmesser war 7,7 mm (von 3–30 mm). In 34 % der Aneurysmen war der Durchmesser 5 mm oder kleiner (n = 16), in 51 % zwischen 6 und10 mm (n = 24) und in 15 % zwischen 11 und 30 mm (n = 7). Nur 1/17 rupturierten Arteria cerebri media Aneurysmen (5,9 %), 4/11 Arteria carotis interna Aneurysmen (36,4 %) und das vertebrobasiläre Aneurysma waren klein. Im Gegensatz dazu war bei 10/18 Arteria cerebri anterior Aneurysmen (55,6 %) der Durchmesser 5 mm oder weniger. ZUSAMMENFASSUNG: Zusammenfassend zeigte sich in unserer konsekutiven Patientenserie mit geklippten cerebralen Aneurysmen nach Subarachnoidealblutung, dass ein Drittel der Patienten kleine rupturierte Aneurysmen hatte, mit dem Arteria cerebri anterior Komplex als Prä­dilektionsstelle. Daher sollten, obwohl bisher niedrige Rupturrisiken berichtet wurden, bei zufällig entdeckten kleinen Aneurysmen, in Abhängigkeit von Lokalisation und individuellen Risikofaktoren, eine Therapie in Betracht gezogen werden.SummaryBACKGROUND: The purpose of this retrospective population-based study was to investigate the incidence of subarachnoid haemorrhage from small (5 mm and below) cerebral aneurysms and their localisation in consecutive patients surgically treated in the State of Vorarlberg/Austria. METHODS: Altogether, during the last 4 years, 82 patients after spontaneous subarachnoid haemorrhage (mean age 53.7 years, range 21–84 years, 47 females and 35 males) were referred to the Neurosurgical Department of the Academic Teaching Hospital Feldkirch, serving for all 360,000 inhabitants of the State (corresponding to a subarachnoid haemorrhage incidence of 5.7/100,000/year). In 70 patients (85.4%), a cerebral aneurysm was detected by computed tomography angiography and/or digital cerebral angiography. Out of these, 47 patients (66.2%, mean age 52.1years, range 24–77 years) were treated with aneurysm clipping and included in the study. Preoperatively, computed tomography, computed tomography angiography and/or digital cerebral angiography were assessed for amount of blood, aneurysm size and localisation, respectively. Clinical status was graded according to the Hunt and Hess classification at admission and according to the Glasgow Outcome Scale at discharge. FINDINGS: According to Koivisto categories, 18 aneurysms were localised at the anterior cerebral artery, 17 aneurysms at the middle cerebral artery, 11 at the internal carotid artery, and 1 at the vertebrobasilar artery. The mean aneurysm diameter was 7.7 mm (range 3–30 mm). In 34% of the aneurysms the diameter was 5 mm or smaller (n = 16), in 51% between 6 and 10 mm (n = 24) and in 15% between 11 and 30 mm (n = 7). Only 1/17 ruptured middle cerebral artery aneurysms (5.9%), 4/11 internal carotid artery aneurysms (36.4%) and the vertebrobasilar artery aneurysm were small. However, in 10/18 anterior cerebral artery aneurysms (55.6%) the diameter was 5 mm or below. CONCLUSIONS: In conclusion, in our consecutive patient series with clipped cerebral aneurysms after subarachnoid haemorrhage, one third had small ruptured aneurysms, with the anterior cerebral artery complex as the main predilection site. Therefore, despite the previously reported low rupture risk, incidental small aneurysms should also be considered for therapy, depending on localisation and individual risk factors.

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