• G Foffani, D Humanes-Valera, F Calderon-Muñoz, A Oliviero, and J Aguilar.
• Neurosignals Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain. guglielmo.foffani@drexel.edu
• Spinal Cord. 2011 Jul 1;49(7):822-6.

Study DesignPharmacologically blocking the spinal cord produces sedative effects and reduces anesthesia requirements in patients and animals. Whether spinal cord injury also reduces anesthesia requirements remains unclear.MethodsWe retrospectively analyzed data from urethane-anesthetized rats (15) to assess anesthesia requirements immediately after complete thoracic transection of the spinal cord. The depth of anesthesia was monitored up to 12 h after spinal transection by the reflexes to noxious stimuli and by electrophysiological recordings from the infragranular layers of the primary somatosensory cortex. Whenever animals displayed electrophysiological and/or behavioral signs of activation, we delivered an additional dose of anesthesia. Anesthetic requirements in animals receiving spinal transection (n=11) were compared with control animals receiving 'sham' lesion (n=9).ResultsThe cumulative dose necessary to maintain a stable level of anesthesia was significantly lower in transected animals compared with control animals. By about 7 h after spinal cord injury, on average the cumulative dose of urethane was only 1.13±0.14 of the original dose, compared with 1.64±0.19 of the original dose in control animals.ConclusionsSpinal transection immediately decreased anesthetic requirements in rats. To establish whether these results are relevant for patients with spinal cord injury will require further investigation.

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