Optic nerve involvement in patients with orbital phlebopathy: Pattern-reversal electroretinograms and visual evoked cortical potentials

Abstract

Pattern-reversal electroretinograms (PERG) and visual evoked cortical potentials (VECP) were recorded from 24 patients with orbital phlebopathy, i.e., characteristic orbital pain and orbital phlebography changes, also occurring in painful ophthalmoplegia (Tolosa-Hunt syndrome). Twelve patients had no visual impairment and 12 had clinical signs of optic nerve involvement.

Only two of the patients with optic nerve involvement had the marked VECP latency prolongation, typically seen in multiple sclerosis, on the orbital pain side. The mean amplitudes of the pattern-reversal ERG and VECP from the eyes on the orbital pain side were significantly reduced, when compared to the reference group. The mean VECP latency from these eyes was not significantly increased. These findings indicate that the optic neuropathy in orbital phlebopathy is characterized by axonal dysfunction rather than demyelination like in multiple sclerosis.

Key Words:

• optic neuropathy
• orbital pain
• orbital phlebography
• visual evoked cortical potential
• elec-troretinogram
• pattern-reversal stimulation