[1] Univ Western Ontario, Dept Paediat, Schulich Sch Med, London, ON N6A 3K7, Canada
[2] Univ Western Ontario, Fac Hlth Sci, London, ON N6A 3K7, Canada
[3] Univ Western Ontario, Dept Paediat & Clin Neurol Sci, London Hlth Sci Ctr, Schulich Sch Med, London, ON N6A 3K7, Canada