James Michael Provenzale MD, Presenter: Nothing to Disclose

YoungJoo Kim, Abstract Co-Author: Nothing to Disclose

Srinivas Peddi, Abstract Co-Author: Nothing to Disclose

David Delong PhD, Abstract Co-Author: Nothing to Disclose

Leonard White PhD, Abstract Co-Author: Nothing to Disclose

To investigate Wallerian degeneration with MR imaging in multiple sclerosis (MS) patients by correlating supratentorial plaque burden (PB) with fractional anisotropy (FA) in normal-appearing white matter (NAWM) tracts.

We assessed PB on proton density-weighted images in 14 MS patients (mean age: 31 years) by identifying and measuring area of all supratentorial plaques in axial sections. DTI was performed using echo planar technique, TR 12,000 ms, TE 101 ms, b 1,000 s/mm2, 6 directions at 1.5T. FA values were compared against age-matched controls. Location of each plaque was noted and plaques grouped by region to facilitate comparison to NAWM tracts. To investigate Wallerian degeneration in corpus callosum (CC), PB in the frontal lobe was correlated with FA in the genu; a summed assessment of PB in remaining lobes was correlated with splenium FA. To investigate the cortico-bulbar/cortico-spinal tract, PB was correlated with FA values of ipsilateral posterior limb of internal capsule, cerebral peduncle and pons. FA correlations were repeated using a measure of PB derived from only plaques that encroached upon the presumptive motor projections in the corona radiata.

Mean FA values were lower in MS patients than controls in combined genu and splenium (p<0.0001), internal capsule (p=0.03), cerebral peduncle (p=0.02), and pons (p=0.06), indicating loss of WM integrity despite normal MR appearance. A correlation (i.e., negative correlation coefficients) was obtained when unilateral PB was compared with ipsilateral components of the cortico-bulbar/cortico-spinal tract. The strongest correlation (r = -0.50) was between the corona radiata PB and pons, consistent with Wallerian degeneration. We found no evidence of Wallerian degeneration in the CC as a function of PB.

The cortico-bulbar/cortico-spinal tracts may undergo Wallerian degeneration as a function of PB. However, it is uncertain whether PB accounts for the full measure of reduced FA in this corticofugal system. Absence of evidence for Wallerian degeneration in the CC suggests primary pathological processes (e.g., axonal loss) also affect NAWM.

Provenzale, J, Kim, Y, Peddi, S, Delong, D, White, L, Diffusion Tensor Imaging Assessment of Wallerian Degeneration in Multiple Sclerosis.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4407392.html