Mori F, Kusayanagi H, Nicoletti CG, Weiss S, Marciani MG, Centonze D. Cortical plasticity predicts recovery from relapse in multiple sclerosis.Mult Scler. 2013 Nov 21. [Epub ahead of print]
BACKGROUND:Relapsing-remitting multiple sclerosis (RRMS) is characterized by the occurrence of clinical relapses, followed by remitting phases of a neurological deficit. Clinical remission after a relapse can be complete, with a return to baseline function that was present before, but is sometimes only partial or absent. Remyelination and repair of the neuronal damage do contribute to recovery, but they are usually incomplete.
OBJECTIVE: We tested the hypothesis that synaptic plasticity, namely long-term potentiation (LTP), may represent an additional substrate for compensating the clinical defect that results from the incomplete repair of neuronal damage.
METHODS:We evaluated the correlation between a measure of LTP, named paired associative stimulation (PAS), at the time of relapse and symptom recovery, in a cohort of 22 newly-diagnosed MS patients.
RESULTS: PAS-induced LTP was normal in patients with complete recovery, and reduced in patients showing incomplete or absent recovery, 12 weeks after the relapse onset. A multivariate regression model showed that PAS-induced LTP and age may contribute to predict null, partial or complete symptom recovery after a relapse.
CONCLUSION:Synaptic plasticity may contribute to symptom recovery after a relapse in MS; and PAS, measured during a relapse, may be used as a predictor of recovery.
Recovery from relapse results from loss of conduction block (inhibition of nerve transmission), remyelination to repair the myelin and so aid transmission and also plasticity, which results from the formation of new synapses (joints between nerves) and the creation of new nerve pathways. This can be seen using functional MRI where brain areas light up due to activity and following some neurological insult different areas of the brain light up completing the same tasks. So the brain rewires and makes new nerve circuits. This is a bit like the internet there are many pathways through which the information can flow and if one pathway gets blocked another pathway is used. Making new synapses helps in this process and the formation of synapses can be influenced by drug treatments. Is new synapse critical for recovery, this study suggests that is is important and that the older we get the less we make synapses, however synapse supporting drugs may be useful.