Are there any features that help differentiate Sjogren's-related CNS demyelinating plaques from multiple sclerosis in a patient with primary Sjogren's syndrome?  

This differentiation can be very difficult but the modified Barkhof's MRI criteria, perivenular lesions, and T2 lesions larger than 6 mm can be helpful in this regard. Helpful references:Kim et al., PMID 23736535Maggi et al., PMID 29328521