Effects of Insula Resection on Autonomic Nervous System Activity

BACKGROUND: The insula is an essential component of the central autonomic network and plays a critical role in autonomic regulation in response to environmental stressors. The role of the insula in human autonomic regulation has been primarily investigated following cerebrovascular accidents, but interpretation of these findings is complicated by lack of control over time-related processes preceding and following cerebrovascular accidents. Surgical resection of tumors in the insula provides unique information about the neural circuits of autonomic dysregulation and subsequent cardiac arrhythmias. METHODS: This study examined autonomic modulation in 2 unique cases during tumor resection of the right and left insula, respectively (WHO grade II low-grade astrocytoma). The patients were monitored for changes in heart rate variability and cardiac arrhythmias before and during tumor resection. RESULTS: Right insular tumor resection was accompanied by significantly increased parasympathetic activity followed by bradyarrhythmias. Removal of the left insula did not change autonomic indices. CONCLUSIONS: These findings suggest that the right insula plays a critical role in parasympathetic autonomic modulation and subsequent cardiac arrhythmias. Additional research is needed to establish the long-term effects of right versus left insula resection as related to autonomic dysregulation and adverse brain-heart interactions, particularly in patients at risk of cardiac arrhythmias.