Chronic subdural hematoma associated with the middle fossa arachnoid cyst: pathogenesis and review of its management.
BACKGROUND
The pathogenesis of chronic subdural hematoma (CSDH) associated with an arachnoid cyst (AC) is still not clear. We propose an origin of initial bleeding of CSDH in patients with AC based on our experience and discuss the management of this disease.


METHODS
The total number of operations included in this study was 23. Eleven cases were indicated because of associated CSDH (group 1), and the other cases were due to different reasons (group 2). The relationship of the AC and dura was evaluated in patients who did not have CSDH (group 2) because patients with CSDH would have had structural changes of AC due to hematoma.


RESULTS
In group 1, the age distribution was from 8 to 61 years (mean 23.0). The development of CSDH was not related with Galassi types. The hematomas were located outside of the outer cyst membrane in six patients and both inside and outside in three patients. In two patients, the location could not be reviewed. After suspicion of the outer cyst membrane as the origin of the bleeding site, we found small bridging vessels between the dura and outer cyst membrane in three of five consecutive patients in group 2.


CONCLUSIONS
Based on our surgical experience of AC cyst, we found small bridging vessels between the dura and outer membrane of the AC. We suggested that these small vessels are the source of initial bleeding leading to CSDH in AC.
Department of Neurosurgery, Kyungpook National University Hospital, 50 Samdeokdong Jung-gu, Daegu, 700-721, South Korea.
Young Seok
YS
Kwak
Sung Kyoo
SK
Hwang
Seong Hyun
SH
Park
Ji Young
JY
Park
D000293:Adolescent; D000328:Adult; D018952:Antigens, CD34 / Q000378:metabolism; D016080:Arachnoid Cysts / Q000150:complications* / Q000473:pathology* / Q000601:surgery; D002648:Child; D005260:Female; D020200:Hematoma, Subdural, Chronic / Q000150:complications* / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000378:metabolism; D012189:Retrospective Studies; D055815:Young Adult
D018952:Antigens, CD34; D018396:Mucin-1