This study showed that axonal loss is one PPMS is less dependent on demyelination and in SPMS, providing further evidence that PPMS is not simply SPMS that skipped the RRMS phase.
[S17.004] Axonal Loss in Primary Progressive MS is Less Dependent on Demyelination than in Secondary Progressive MS
Emma C. Tallantyre, Nottingham, United Kingdom, Lars Boe, Bergen, Norway, Lowe James, Nikos Evangelou, Nottingham, United Kingdom.
The questions examined here were whether axonal loss correlates with disability, and are there different patterns of axonal loss in PPMS and SPMS. Cervical spinal cord autopsy sections from 17 PPMS subjects, 30 SPMS subjects, and 7 controls were stained for myelin and neurofilament (a protein in axons). The extent of demyelination was higher in both white matter and gray matter in SPMS subjects compared with PPMS. Most lesions in both groups were classifed as "chronic inactive." SPMS and PPMS subjects had similar amounts of axonal loss overall, which correlated with EDSS scores immediately before death. However, in lesions, axonal loss was higher in PPMS than in SPMS. So while there were fewer plaques in the PPMS samples, those plaques had higher levels of axonal loss. The research team will be doing a similar analysis lower down the spine in the lumbar region to see if the same pattern exists there.