Epub ahead of print: Naismith et al. Diffusion Tensor Imaging in Acute Optic Neuropathies: Predictor of Clinical Outcomes. Arch Neurol. 2011 Sep 12.
Objective: To evaluate a MRI technique called Diffusion Tensor Imaging (DTI) within the optic nerve in a first event of acute optic neuritis to determine whether it would predict 6-month visual outcome.
“DTI is an MRI technique that detects the structural integrity of nerve fibres.”
Outcome: Visual acuity, contrast sensitivity (how well you can detect gray scale changes), visual evoked potentials (VEPs or electrical function of the optic nerves), and thickness of the retinal nerve fiber layer (RNFL, an index of the number of axons or neurones in the optic nerve).
Results: An incomplete 6-month visual recovery was associated with a lower baseline score on DTI compared to MS’ers who make a complete recovery. A lower baseline score on DTI correlated with worse 6-month visual outcomes in visual acuity, contrast sensitivity, VEP amplitude (correlates with number of surviving axons), VEP latency (speed of electrical conduction), and RNFL thickness (number of surviving axons).
Conclusions: Abnormal DTI in acute optic neuritis was associated with a worse 6-month visual outcome and correlated with VEP and RNFL measures of axon and myelin injury.
“This study is important, it confirms other studies findings, that optic neuritis is not benign and causes significant axonal damage early on. This justifies us using optic neuritis to test neuroprotection strategies in MS’ers. The reason for targeting the optic nerve, unlike other systems, is that it allows us to measure the anatomy and function of the nerve very well.”
“You may be aware that the NMSS are sponsoring a trial of acute neuroprotection in optic neuritis in the UK; we are about to start the trial. This is part of the translational programme that came out of Promise 2010.”
Additional reading: DTI