Spinal cord hypothermia without systemic hypothermia

Abstract

Background and purpose: Hypothermia has been shown to be beneficial in the setting of acute SCI. However, widespread use has been hindered by the need for systemic hypothermia as the vehicle for achieving spinal cord hypothermia. This study demonstrates that localized spinal cord hypothermia can be achieved via a percutaneous approach while maintaining systemic normothermia.

Materials and methods: Five Yucatan swine underwent catheterization of the subarachnoid space and infusion of room temperature, chilled, and iced PL solutions into the cervical spinal canal, with drainage from the lumbar canal. Thermocouples were placed within the spinal cord and in the subarachnoid space and recorded during infusions and recovery from hypothermia.

Results: Results demonstrated that hypothermia as low as 16.8°C is feasible in the spinal cord with retention of systemic normothermia, with strong (r = 0.95) correlation between the spinal cord temperature and the CSF temperature. Degrees of cooling varied with flow rates and with infusate temperature.

Conclusions: While the data are preliminary in a small group of animals, the ability to rapidly create a wide range of controlled spinal cord hypothermia while preserving normal body temperature warrants wider exploration. The study also indicates that further investigation of the hypothesis that CSF temperature monitoring may be an acceptable surrogate for direct spinal cord temperature monitoring should be pursued.

Fig 1.

Anteroposterior (AP) (A) and lateral (B) radiographs obtained at the time of needle placement in the lower cervical spinal cord (C6–7 level) of animal 3, demonstrating placement of the needle tip (long arrow) within the spinal cord on both views. The short arrow shows the tip of the microcatheter (better seen on the AP view) through which both the contrast and the eventual hypothermic infusion were injected.

Fig 2.

Scatterplot of spinal cord temperatures (y-axis) versus CSF temperatures (x-axis) (n = 255 observations). Note the tendency at lower temperatures for CSF temperatures to be higher than spinal cord temperatures.