[Diagnosis and differential diagnosis of demyelinating optic neuropathy in multiple sclerosis]

The previous research has shown the very common subclinical damage of the optic nerve in multiple sclerosis patients with the absence of obvious clinical symptoms of optic neuropathy (ON). Other causes of ON (pathology of connective tissue, infections, tumors or ischemic diseases) are rather uncommon. We carried out a detailed neuroophthalmologic examination of 137 (274 eyes) patients with relapsing-remitting multiple sclerosis (MS) including 58 patients (74 eyes) with a previous history of ON. Acute clinical symptoms of ON were recorded in 42% of MS patients. Moreover, in 31% of ON patients, ON was the first and only symptom of MS. In other 56% of MS patients, a subclinical damage of the optic analyzer was recorded. The examination of the central vision fields with the help of standard static automated perimetry ("Humphrey"-24/2) showed the reduction of the light sensitivity threshold in 90% of MS cases and in 100% ON cases. The contrast sensitivity was considerably reduced in the whole frequency band, including high frequency, in MS patients with the previous history of ON and with MS lasting for over 5 years. The use of the Sloan low-contrast test revealed the sharp reduction in the identification of signs with the contrast level of 2,5% and 1,25% in all ON cases and in 70% MS cases without ON. In 82% of MS cases, the pattern visual evoked potentials (PVEP) revealed the increase in P100 latent period from 10 to 50 msec above the upper norm limit. A distortion of the shape of PVEP P100 complex of W-type and amplitude reduction were recorded in over 90% MS cases with the previous history of ON. The use of optical coherence tomography (OCT) revealed that the average thickness of the retinal nerve fiber layer (RNFL) in MS was decreased compared to the control group (87 (76; 97) and 105 (99; 115) microns, respectively). Patients with the previous history of ON had the lowest RNFL thickness of 73 (65; 84) microns. Diffusion tensor imaging showed that the index of fractional anisotropy (FA DTI) was considerably reduced in the optical nerve area and tract. Its average value was equal to 570,0 (510; 615) versus 651,9 (610; 710) microns in the control group.