Horner's syndrome: a complication of experimental carotid artery surgery in rats.

Purpose: To report on the occurrence of iatrogenic Horner's syndrome (HS) in epileptic rats after implantation of an electrode for vagus nerve stimulation and to describe the possible consequences of this new complication of carotid artery surgery in rats.
Methods: A bipolar circular electrode was placed around the left carotid artery and vagus nerve of 31 rats. The incidence of HS was evaluated by visual inspection within 24 h after surgery.
Results: 68% of rats suffered from HS immediately after surgery. This complication did not affect epileptogenesis.
Conclusion: The occurrence of HS in the rat is a frequent complication of vagus nerve electrode implantation, which does not affect epileptogenesis in this study. However, rats affected by HS may suffer from damage to the sympathetic innervation of the gut, due to rat-specific neuroanatomy. Therefore, caution towards other research questions is warranted.