[1] Kings Coll London, Sch Med, London SE1 1UL, England
[2] Kings Coll Hosp Fdn Trust, Dept Neurosurg, London SE5 9RS, England
[3] Ente Osped Cantonale, Neuroctr Southern Switzerland, Dept Neurosurg, CH-6900 Lugano, Switzerland
[4] Kings Coll Hosp Fdn Trust, Dept Neurophysiol, London SE5 9RS, England
[5] Kings Coll Hosp Fdn Trust, Dept Neuroradiol, London SE5 9RS, England