With the exception of systematic review  (HAMLET and HeADDFIRST [11 patients in HAMLET and 8 patients in HeADDFIRST]), patients included in the randomized trials and their pooled analyses were treated within 48 hours of symptom onset.
Similar to the results of HeADDFIRST , requiring significant mass effect within 96 hours of stroke onset for randomization, we did not find an increase in disability or mortality with delayed surgery [after 48 hours].
The low mortality observed in the conservatively treated patients randomized after 48 hours (36% in HAMLET and 40% in HeADDFIRST) compared with patients randomized less than 48 hours (78% in HAMLET, 53% in DESTINY, and 78% in DECIMAL) points to a possibility of two different MMCA stroke groups, that is, the group of those that deteriorate more rapidly and hence were operated on early and the group of those that deteriorate slowly and hence were operated on late.
Decompressive hemicraniectomy for severe ischemic stroke currently is being investigated in major clinical trials, such as the Hemicraniectomy after MCA Infarction with Life-threatening Edema Trial (HAMLET), Hemicraniectomy and Durotomy for Deterioration from Infarction Related Swelling Trial (HeaDDFIRST
), Hemicraniectomy and Moderate Hypothermia in Patients with Severe Ischemic Stroke and Hemicraniectomy for Malignant Cerebral Artery Infarcts (HeMMI) (Internet Stroke Center, 2004).