[1] Dow Med Coll, Karachi, Pakistan
[2] Ziauddin Med Coll, Karachi, Pakistan
[3] Banner Univ, Med Ctr, Dept Neurol, Tucson, AZ USA
[4] Baylor Coll Med, Dept Neurol, Div Vasc Neurol & Neurocrit Care, Houston, TX 77030 USA
[5] Riverside Univ Hlth Syst, Med Ctr, Chair Neurosurg, Moreno Valley, CA USA
[6] Vancouver Gen Hosp, Dept Radiol, Vancouver, WA USA