Incidence and risk factors of chronic subdural hematoma after aneurysmal clipping.
OBJECTIVE
Chronic subdural hematoma (CSDH) after aneurysmal clipping is a rare complication, but its incidence and risk factors are not known in detail. We retrospectively reviewed our cases requiring surgery for CSDH after clipping.


METHODS
In our hospital, between January 2000 and December 2006, 794 patients (unruptured, 58.0%) underwent clipping surgery for aneurysm of the anterior circulation. We reviewed incidence and risk factors of CSDH after clipping. For the past 2 years, we reviewed all computed tomography scans for 163 unruptured aneurysms, and examined the relationship between an increase of subdural fluid collection (SFC) and development of CSDH.


RESULTS
Fifteen patients (1.9%) developed CSDH after clipping, which required evacuation. Among those, 13 had unruptured aneurysms (2.8%), a much higher percentage than for ruptured aneurysms (0.9%). On univariate statistical analysis, risk factors of CSDH were associated with advanced age (P = 0.0005), male gender (P = 0.04), and unruptured aneurysms (P = 0.02). Aneurysmal location was not related to the development of postoperative CSDH. Contralateral CSDH occurred in 3 patients, but no middle cerebral artery aneurysm developed contralateral CSDH. An increase in postoperative SFC during 1 week was a significant risk factor for CSDH (P = 0.001).


CONCLUSIONS
In addition to the classic risk factors, this study showed that clipping for unruptured aneurysms carries a higher risk for CSDH compared to ruptured aneurysms. We suggest that an increase of SFC during 1 week postoperatively can be a factor in predicting CSDH after clipping.
Department of Neurosurgery, National Cerebral and Cardiovascular Center, Suita, Japan. Electronic address: tohno@higashi-hosp.jp.
Takayuki
T
Ohno
Koji
K
Iihara
Jun C
JC
Takahashi
Norio
N
Nakajima
Tetsu
T
Satow
Tomohito
T
Hishikawa
Izumi
I
Nagata
Kazuo
K
Yamada
Susumu
S
Miyamoto
D000368:Aged; D003399:Craniotomy / Q000706:statistics & numerical data; D005260:Female; D020200:Hematoma, Subdural, Chronic / Q000000981:diagnostic imaging / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013525:Surgical Instruments; D014057:Tomography, X-Ray Computed; D014656:Vascular Surgical Procedures / Q000706:statistics & numerical data*