Is optic neuritis more benign than other first attacks in multiple sclerosis?
Tintore M, Rovira A, Rio J, Nos C, Grive E, Tellez N, et al.;
Commented by , 19 Feb 2005
Background
The relationship between onset symptoms in MS and prognosis has been thoroughly examined in retrospective studies. Nonetheless, prospective studies have not confirmed the notion that optic neuritis (ON) or other topographic location of MS pathology predicts a more benign disease course. The current study aims at describing this discrepancy in a prospective study of patients with clinically isolated syndrome (CIS).
Aim
To compare conversion to MS either clinically (second attack) or by MRI (dissemination in time and space) on different topographies of CIS.
Methods
The study design was longitudinal and incorporated 320 patients diagnosed with CIS, median clinical follow-up was 39 months. Symptoms were divided into
- ON (123)
- brainstem (78)
- spinal cord (89)
- other topography (30)
A CSF analysis of oligoclonal bands, as well as brain MRI was carried out. Conversion to clinically definite MS (CDMS) was diagnosed according to the Poser or the McDonald criteria. The statistical approach was ANOVA and X2 (differences among groups), odds ratio and Cox's proportional hazard model (association between topography and time to CDMS).
Results
Normal baseline brain MRI was found in 102 patients (33%). McDonald criteria for dissemination in space were fulfilled in 165 patients (56%). During the first year, 255 patients (80%) underwent MRI and 124 (48.6%) had a new T2 lesion and then fulfilled McDonald criteria for MS. A total of 47 (14.7%) had a second attack and fulfilled the Poser criteria for MS.
In the different subgroups, baseline MRI was abnormal in 50.8% of patients with ON, 76.3% of patients with brainstem lesions, 75.9% of patients with spinal cord symptoms and 81.5% of patients with other topography. A similar pattern was seen for abnormal CSF analysis.
Patients with ON had a significantly lower conversion rate to CDMS due to relapse or MRI dissemination, compared with other presentation of onset symptoms.
In a selected subgroup of patients with abnormal MRI, the authors found no difference of conversion to MS between different topographies.
Dr Blinkenberg's comments
The study shows that patients with ON have a reduced risk of developing MS compared with other CIS. However, the authors found a reduced number of abnormal baseline MRI in ON patients compared with other topographies.
The study demonstrates that the increased number of normal baseline brain MRI explain why ON previously have been considered to be associated with a better outcome than other MS debut symptoms.
Taking into consideration that approximately 50% of ON have abnormal baseline MRI and approximately 40% have oligoclonal bands still underline the importance of MRI and CSF examination in this group of patients.
The study also shows that patients with abnormal baseline MRI have the same conversion rate to MS regardless of topography. In this way MRI is superior to CIS topography as a predictor of conversion rate and the same is true for true for CSF oligoclonal band analysis.
Together, the two tests provide important data with regard to counseling and early treatment in MS. The study confirms recent data from the ETOMS1 and CHAMPS2 study showing that if the MRI is abnormal, any presenting CIS symptom carries the same likelihood of predicting MS.
References
1. Comi G, Filippi M, Barkhof F, Durelli L, Edan G, Fernandez O, Hartung H, Seeldrayers P, Sorensen PS, Rovaris M, Martinelli V, Hommes OR. Effect of early interferon treatment on conversion to definite multiple sclerosis: a randomised study. Lancet 2001; 357 (9268); 1576-82.
2. Jacobs LD, Beck RW, Simon JH, Kinkel RP, Brownscheidle CM, Murray TJ, Simonian NA, Slasor PJ, Sandrock AW. Intramuscular interferon beta-1a therapy initiated during a first demyelinating event in multiple sclerosis. CHAMPS Study Group. N Engl J Med 2000; 343 (13); 898-904.