Sonography of optic nerve sheath diameter identifies patients with middle cerebral artery infarction at risk of a malignant course: a pilot prospective observational study.

INTRODUCTION: To assess the value of optic nerve sheath diameter (ONSD) measurements at different time points to predict the malignant evolution in middle cerebral artery (MCA) infarction and to investigate the relationship between ONSD and infarct volume on follow-up computed tomography (CT). METHODS: In a single-center prospective observational study, we recruited patients with MCA infarction and age- and sex-matched controls. Clinical characteristics including NationaI Institutes of Health Stroke Scale (NIHSS) and ONSD measurement were assessed during the first five days after symptom onset. Volumetric analysis of the infarction was performed by a neuroradiologist, who was blinded to results of ONSD measurement and clinical examinations, based on  CT scans. RESULTS: We enrolled 29 patients with MCA infarction, including 10 with malignant MCA (mMCA) infarction and 14 controls. Mean ONSD on admission was already larger in patients who had developed an mMCA (5.99 ± 0.32 mm) compared to patients with MCA infarction (4.98 ± 0.53 mm; P = 0.003), and to control patients (4.57 ± 0.29 mm; P < 0.001). Correlation was observed between the ONSD mean value bilateral measures per individual and volumetric evaluation of cerebral infarction in the CT scan after one day (r = 0.623; P = 0.002). An ONSD value of 5.6 mm predicted an mMCA with a sensitivity of 100% and specificity of 90% yielding a positive predictive value of 83% and negative predictive value of 100%. CONCLUSIONS: ONSD measurement might be accurate for the noninvasive detection of increased ICP and for the recognition of patients being likely to develop mMCA.