ANI Parasympathetic Monitoring in Neurosurgery

Surgery of large cerebellopontine angle (CPA) tumors (\>2 x 2 cm diameter), with compression of the pons exposes the patient to inadvertent parasympathetic nerve stimulation (IPNS) leading to bradycardia and asystole. The analgesia nociception index (ANI) monitor assesses the balance between analgesia and nociception through the detection of parasympathetic tone. ANI \>80 generally denotes excessive analgesia (EA). The main objective of this study was to determine whether ANI values for IPNS are different or the same as ANI values for EA. This study also aims at calculating the number of patients with IPNS and EA during surgery of large CPA tumours.