Objective
To determine non-invasively the relation between the degree of Axonal loss and the extent of DeMyelination in chronic lesions visible on MRI.
In patients with different subgroups of Clinically Definite Multiple Sclerosis using 1H Magnetic Resonance Spectroscopy (1H MRS) and Magnetization Transfer imaging (MT).
Conventional MRI is unable to differentiate between the various pathological processes occurring in the Multiple Sclerosis lesion. There are, however, newer MR techniques which show promise in this respect.
Methods
1H MRS and MT were performed in 18 patients with Clinically Definite Multiple Sclerosis who had a wide range of disability and disease duration.
Results
A significant correlation was found between a reduction in the concentration of N-AcetylAspartate (NAA); an in vivo marker of Axonal loss or dysfunction.
And, a reduction in MT Ratio (a probable marker of DeMyelination) in patients who had entered the Secondary/Progressive stage of the disease.
Patients with minimal Disability after a disease duration greater than 10 years - called Benign Multiple Sclerosis - showed a relative preservation of NAA and MT.
Conclusions
Because a reduction in MT seems to be a relative marker for DeMyelination and a reduction of NAA from chronic Lesions is indicative of Axonal loss, this study supports the hypothesis that DeMyelination and Axonal Loss occur in the same chronic Multiple Sclerosis lesions.
In addition, the degree of Axonal loss and DeMyelination correlates with clinical Heterogeneity.
- Comment in: J Neurol NeuroSurg Psychiatry 1999 Dec;67(6):708-9
