Decompressive craniectomy index: Does the size of decompressive craniectomy matter in malignant middle cerebral artery infarction?

BACKGROUND: Malignant middle cerebral artery (MCA) infarction is associated with high mortality, mainly due to intracranial hypertension. This malignant course develops when two-thirds or more of MCA territory is infarcted. Randomized clinical trials demonstrated that in patients with malignant MCA infarction, decompressive craniectomy (DC) is associated with better prognosis. In these patients, some prognostic predictors are already known, including age and time between stroke and DC. The size of bone flap was not associated with long-term prognosis in the previous studies. Therefore, this paper aims to further expand the analysis of the bone removal toward a more precise quantification and verify the prognosis implication of the bone flap area/whole supratentorial hemicranium relation in patients treated with DC for malignant middle cerebral infarcts. METHODS: This study included 45 patients operated between 2015 and 2020. All patients had been diagnosed with a malignant MCA infarction and were submitted to DC to treat the ischemic event. The primary endpoint was dichotomized modified Rankin scale (mRS) 1 year after surgery (mRS≤4 or mRS>4). RESULTS: Patients with bad prognosis (mRS 5–6) were on average: older and with a smaller decompressive craniectomy index (DCI). In multivariate analysis, with adjustments for “age“ and “time” from symptoms onset to DC, the association between DCI and prognosis remained. CONCLUSION: In our series, the relation between bone flap size and theoretical maximum supratentorial hemicranium area (DCI) in patients with malignant MCA infarction was associated with prognosis. Further studies are necessary to confirm these findings.