Intra-operative diabetes insipidus associated with cervical spine traction during staged scoliosis surgery.

A 15-year-old boy with cerebral palsy and epilepsy presented for a posterior spinal fusion as part of staged repair of thoracolumbar scoliosis. Total intravenous anaesthesia was induced and maintained with propofol, remifentanil and ketamine. Following prone positioning, cervical traction was applied. Polyuria developed intra-operatively, from 4 to 18 ml.kg-1.h-1. There was a corresponding rise in plasma sodium concentration from 132 to 145 mmol.l-1. Haemodynamic stability was maintained with boluses of Hartmann's solution and a noradrenaline infusion. Given the possibility of diabetes insipidus due to reduced cerebral perfusion pressure, the cervical traction was removed. This initially showed a good response with a transient reduction in polyuria to 3 ml.kg-1.h-1 before rising to 8 ml.kg-1.h-1. Subsequently, a vasopressin infusion was started with normalisation of diuresis and plasma sodium concentration by the end of surgery. Diabetes insipidus is an endocrine disorder related to lack of production or insensitivity to vasopressin. In the peri-operative period, it is mainly associated with pituitary surgery and rarely with spinal surgery. To the authors' knowledge, this is only the second report of diabetes insipidus associated with staged scoliosis surgery. Cervical traction should be considered as a potential cause of intra-operative diabetes insipidus.