['To compare continuous jugular venous bulb oximetry and cerebral near-infrared spectroscopy in patients with severe closed head injury.', 'A prospective observational study.', 'Intensive care unit of a major teaching hospital.', 'Adults (n = 10) with severe closed-head injury (Glasgow Coma Scale score of < or = 8).', 'None.', 'Jugular venous bulb oximetry, cerebral near-infrared spectroscopy, and cerebral perfusion pressure were measured continuously. A total of 3,691 paired measurements of near-infrared spectroscopy and jugular venous bulb oximetry were analyzed. Poor correlation (r2 = .04) between paired measurements and wide limits of agreement (-13% to +21%) were demonstrated. The mean difference between measurements was +/- 4% and the standard deviation of the mean difference was +/- 8.69%. The data were subsequently grouped according to three clinically significant subgroups of jugular venous bulb oxygen saturation reflecting low ( < 55%), normal (55% to 75%) and high ( > 75%) saturation values. Poor correlation and wide limits of agreement between the two methods of measurement were observed in all groups. Values recorded by near-infrared spectroscopy did not significantly change between the groups, and 14 clinically significant episodes of jugular venous bulb desaturation were not detected by near-infrared spectroscopy.'] Is cerebral oxygenation monitoring by near-infrared spectroscopy clinically useful in patients with severe closed-head injury : a comparison with jugular venous bulb oximetry?