Received: 20 September 2017
Accepted: 23 March 2018
First Online: 25 April 2018
Ethics approval and consent to participate
: The study was approved by the ethical committee of the department of Neurology and Clinical Neurophysiology, Faculty of Medicine, Cairo University. All subjects provided informed consent to participate in the study.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.