THE LOCALIZING VALUE OF ASYMMETRY IN PUPILLARY SIZE IN SEVERE HEAD-INJURY - RELATION TO LESION TYPE AND LOCATION

RELIABLE ASSESSMENT OF the probability that a head injury patient harb ors a surgical intracranial lesion is critical to both triage and trea tment. The authors analyzed data from 608 patients with severe head in juries (Glasgow Coma Scale score, less than or equal to 8) in the Trau matic Coma Data Bank to assess the reliability of pupillary asymmetry in predicting the presence and location of an intracranial mass lesion . Of 210 patients with pupillary asymmetry of greater than or equal to 1 mm, 63 (30%) had intracranial mass lesions, 52 (25%) of which were extra-axial in location, 38 (73%) of these located ipsilateral to the larger pupil. Of 51 patients with asymmetry of greater than or equal t o 3 mm, 22 (43%) had intracranial mass lesions, 18 (35%) of which were extra-axial in location, 14 (64%) of these located ipsilateral to the larger pupil. For both asymmetry categories, strong interactions were found with age and mechanism of injury, the highest incidence of extr a-axial lesions occurring in older patients injured other than as occu pants of motor vehicles. The authors developed regression equations th at provide a graphic means to predict the presence of an intracranial hematoma using data on pupillary asymmetry, age, and mechanism of inju ry. This predictive model, interpreted in a hospital- and patient-spec ific fashion, should be of significant use in directing triage, activa ting diagnostic and therapeutic resources, and evaluating the utility of exploratory trephination.