Significance of novel subcortical low intensity score on transient neurological events after revascularization surgery for moyamoya disease

Abstract

ObjectivesTransient neurological events (TNEs) are frequently observed after revascularization surgery for moyamoya disease (MMD). Recently, two signs on fluid-attenuated inversion recovery magnetic resonance images, a cortical hyperintensity belt (CHB) sign possibly reflecting vasogenic edema and a transient subcortical low intensity (SCLI) sign possibly reflecting cytotoxic edema, were reported associated with TNEs. The purpose of this study was to create a SCLI score and to investigate the significance of the score in TNEs. Patients and methodsThe authors retrospectively analyzed 18 cerebral hemispheres in 16 consecutive patients with revascularization surgery for MMD. The SCLI sign was defined as a transient SCLI in surgically treated hemispheres, and blindly graded as the SCLI score (0–4) based on the extent. The relationships among SCLI, CHB signs and TNEs were evaluated. ResultsPostoperative TNEs, SCLI and CHB signs were detected in 8 (44.4%), 9 (50.0%) and 12 (66.7%) hemispheres, respectively. Patients with SCLI and CHB signs had a significantly higher TNE occurrence rate than those without these signs (p = 0.015, and p = 0.013, respectively). Patients with TNEs showed significantly higher SCLI scores than those without TNEs (p = 0.009), while the difference of CHB scores did not reach significance between patients with and without TNEs. For the occurrence of postoperative TNEs, SCLI score with a cut-off value of 1.0 resulted in a specificity of 80.0% and a sensitivity of 87.5%. ConclusionThe novel SCLI score may be useful for diagnosing TNEs after revascularization surgery for MMD, although both vasogenic and cytotoxic edema may be involved in postoperative TNEs.