Cerebrospinal fluid pressure measurement in the ovine intrathecal space: a preliminary study towards the diagnosis of intrathecal drug administration catheter dislodgement or occlusion.

BACKGROUND AND
OBJECTIVE: Intrathecal drug delivery catheter malfunctions are a principal cause of therapy interruption. We determined that normal baseline intrathecal cerebrospinal fluid (CSF) pressure recordings could be obtained in an ovine model and in a catheter dislodgement scenario.
METHODS: Two sheep were implanted with spinal catheters: 2 in the T(6) epidural space in sheep No. 1; 1 T(6) intrathecal catheter plus 1 L(2) epidural catheter with a deliberate CSF leak to simulate dislodgement in sheep No. 2. Pressure waves were recorded intraoperatively and at multiple times after the implantation in the awake condition. On day 21, the animals were anesthetized for pressure recordings while on and temporarily off mechanical ventilation. They were then necropsied.
RESULTS: CSF pressure waves were obtained in this animal model under anesthesia with or without mechanical ventilation and in the awake state. Fluid accumulation at the tip of a dislodged (epidural) catheter temporarily caused apparent coupling of fluid pressures across the dura. An unintentional extraspinal fluid collection in sheep No. 2 was associated with a raised baseline epidural pressure.
CONCLUSIONS: These findings support the notion that pressure sensors can play a role in determining the status of intraspinal drug delivery catheters.