- Correspondence to Dr M A J Tijssen, Department of Neurology AB 51, University Medical Centre Groningen (UMCG), PO Box 30.001, Groningen 9700 RB, The Netherlands;
- Received September 7, 2012
- Revised January 18, 2013
- Accepted January 22, 2013
- First published February 14, 2013.
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