Thin Acute Subdural Hematoma: Part 2 : Role of Surgery

ABSTRACT

A retrospective study on 78 cases of surgically treated acute(within 24 hours) subdural hematoma(ASDH) with special reference to the size is presented. The thin ASDH is defined as the hematoma of which thickness is less than 3 mm in the printed CT film(true thickness about 10 mm). 27 cases are the thin ASDH and 51 cases are the not-thin ASDH. Pre-operative Glasgow coma score(GCS1), Postoperative Glasgow coma score(GCS2) and difference between GCS2 and GCS1(GCS2-GCS1) are compared in two groups by student t-tests. The mean GCS2 is worse than the mean GCS1 in the thin ASDH. In the not-thin ASDH, the mean GCS2 is better than the mean GCS1. Futhermore, in the thin ASDH, the mean difference between GCS2 and GCS1 is -1.04("-" means deteriorated after operation). In the not-thin ASDH, it was 0.77. In the thin ASDH, 44.4% is deteriorated(GCS2-GCS1 or = 2). In the not-thin ASDH, 31.4% is improved and 17.6% is deteriorated. Comparisons between the improved cases and the deteriorated cases with various factors are made by chi square tests. Four statistically significant differences are found. The size of hematoma and midline shift are rather smaller in the deteriorated cases, but brain swelling or contused underlying cortex is more commonly observed during operation in the deteriorated cases and craniectomy with or without excision of the contused cortex is more frequently performed. One possible explanation of these results is that surgical decompression on the thin ASDH may cause or exercerbate brain swelling, hemorrhagic contusion or intracerebral hematoma-justlike "popping", thus replacement of the bone flap is difficult. Therefore, the thin ASDH should not be operated immediately, but closely observed in the ICU. If deteriorated, seek for the causing lesion by such as repeated CT scanning, then, treat the causing lesion, often it is not the ASDH itself.