[1] Leiden Univ, Dept Neurosurg, Med Ctr, Leiden, Netherlands
[2] Leiden Univ, Dept Rheumatol, Med Ctr, Leiden, Netherlands
[3] Hague Med Ctr, Dept Neurosurg, The Hague, Netherlands
[4] HAGA Teaching Hosp, The Hague, Netherlands
[5] Spaarne Hosp Haarlem Hoofddorp, Dept Neurosurg, Hoofddorp, Netherlands