The relationship between lesion volume, oligoclonal bands, and cerebrospinal fluid/serum albumin ratio in multiple sclerosis

Objectives: This study aimed to investigate the association between the presence of oligoclonal bands (OCB) in cerebrospinal fluid (CSF), immunoglobulin G (IgG) index, CSF/serum albumin ratio, demyelinating lesions (number and volume), and brain atrophy in patients with multiple sclerosis (MS). Patients and methods: A total of 47 patients diagnosed with MS, with OCB type 1 (n=21; 14 females, 7 males; median age: 34 years; range, 21 to 58 years) and type 2 (n=26; 20 females, 6 males; median age: 31 years; range, 20 to 53 years) detected, were retrospectively examined between July 2022 and July 2023. Cerebrospinal fluid biomarkers, the number, volume, and distribution (periventricular, subcortical, juxtacortical, or infratentorial) of demyelinating lesions, and lesion burden were compared. The presence of atrophy in the cerebrum, cerebral gray matter, cerebellum, and brainstem at baseline, and Expanded Disability Status Scale (EDSS) scores at baseline, were recorded. Results: The IgG index was statistically significantly higher in patients with OCB type 2 compared to type 1 (p<0.05), irrespective of whether it exceeded 0.70. No significant associations were found between OCB types and CSF/serum albumin ratio, baseline EDSS scores, and baseline total demyelinating lesion volume and distribution (p>0.05). A moderate positive correlation was observed between IgG index and periventricular lesion volume (r=0.507, p<0.05). No significant correlation was found between any two of the other parameters. Among individuals with OCB type 1, atrophy was observed in the total cerebrum (47%), total cerebral gray matter (38%), cerebellum (4.7%), and brainstem (28.5%). Among individuals with OCB type 2, atrophy was observed in the total cerebrum (69%), total cerebral gray matter (26%), cerebellum (4.7%), and brainstem (15.3%). However, atrophy was not directly associated with CSF biomarkers or EDSS score. Conclusion: The association between the volume of periventricular lesions (PVL) and the IgG index suggests that this may be related to proximity to cerebrospinal fluid; however, the number of PVLs does not seem to provide additional diagnostic information. The detection of brain atrophy in most patients has highlighted the need for more comprehensive disease severity scales to evaluate the location and clinical implications of atrophy in MS.