[Flash-evoked visual potentials in the early diagnosis of optic nerve injury due to craniofacial fractures]

Abstract

Impairment or loss of vision due to optic nerve injury occurs in about 10% of patients with cranio-facial fractures. The assessment of optic nerve function is important for decisions regarding optic nerve decompression. But examination of vision and pupillary reflexes may be difficult, especially in uncooperative patients with reduced consciousness and primary disturbances of pupillary functions. In these cases, optic nerve function can be monitored by means of flash-evoked visual potentials elicited by use of a LED-goggle stimulator. VEPs were recorded in ten patients with head injuries comprising cranio-facial fractures and cerebral concussion with prolonged alteration of consciousness. Recordings were obtained in the acute phase upon admission. Visual acuity and visual fields were examined after regaining consciousness and the clinical findings correlated to the initial VEPs. Upon clinical examinations, four patients with initially normal VEPs had normal vision on both eyes. One patient initially revealed unilateral reduction of the VEP-amplitude of more than 50% and clinically showed a concentric visual field defect. Three patients with unilateral loss of potentials were amaurotic on this side. Perception of light was preserved in one patient in whom VEPs were absent. One patient with bilateral loss of potentials was blind when consciousness was regained. In general, pupillary light reflexes tested at admission corresponded to the VEP-findings. In two cases, however, pupillary reactivity was lost, but VEPs were still present. These patients had normal vision, but exhibited a lesion of the efferent pathways of pupillary reflexes. In two other patients, examination of pupillary reactivity could not be performed due to extreme edema of the eyelids.(ABSTRACT TRUNCATED AT 250 WORDS)