The value of the visual evoked potentials test in the assessment of the visual pathway in head trauma

The research was done to evaluate the value of the visual evoked potentials test in the assessment of visual pathways function in cases with head trauma and minimal findings on routine testing.

A prospective case series evaluating use of visual evoked potentials testing in patients with a history of head trauma and suffering from visual symptoms with no significant clinical and neuroimaging findings, referred for further work up.

Thirty-four patients with a history of head trauma and subsequent visual complaints were included. 27 cases (79.4%) were male and 7 cases (20.6%) were female. The mean elapsed time after the trauma was 47.6 weeks (range: 3.5 to 320 weeks). Twenty-five cases had unilateral and 9 cases had bilateral visual complaints. History of coma with mean duration of 12 days was present in 4 cases. The best-corrected visual acuity was less than 1 Log MAR (legally blind) in 21 eyes. In 4 eyes (12%) the relative afferent papillary defect test was positive. Mild to moderate optic disc pallor was present bilaterally in 4 cases and unilaterally in 3 cases. Hemorrhagic patches were reported on MRI in 2 cases; no other cases had pathologic MRI findings. In unilateral cases, there was a statistically significant difference between the involved eye-sided lobe and the sound eye-sided lobe implicit time and amplitude. In patients with bilateral complaints, by testing each eye, the VEP amplitudes of both eyes showed significant differences with the International Society for Clinical Electrophysiology of Vision standards, whereas the implicit times showed not-statistically significant differences.

The visual evoked potentials test shows not only additional diagnostic value, not seen on routine clinical and neuroimaging testing, but also rather a high validity in tracing visual disability in traumatic brain injury.