“…Because the intracerebroventricular route is a precarious one, unsuited to regular administration to the same patient, a number of ways to circumvent this problem are being developed to widen the use of these highly successful biological agents to a new patient group. The earliest of these is a novel approach termed the perispinal route (Tobinick et al, 2006(Tobinick et al, , 2010(Tobinick et al, , 2012. Its logic depends on 1) a short period of head-down tilting to gain a gravitational advantage, 2) an awareness of anatomy of Batson's plexus [a valveless venous system that surrounds the spinal column in continuum with the choroid plexus (Nathoo et al, 2011)], and 3) knowledge of the effect of acute hypertension on choroid plexus permeability [a 30-fold increase in albumin in CSF within 10 min of pharmacologically induced acute local hypertension (Murphy and Johanson, 1985)].…”