Approach to a Parturient with Arnold Chiari Malformation: A Team Controversy.

Introduction: Arnold Chiari Malformation (ACM) is characterized by displacement of cerebellar tonsils below the foramen magnum, with potential risk of cerebral herniation. Labor increases risk of complications because of the acute increase in intracranial pressure (ICP). Literature isn’t consensual in the anesthetic management in parturients with non-surgically corrected ACM.
Case Report: 35yo, 70kg, ASA II, GIIPI, active phase of labor, without previous evaluation by Anesthesiology. Prior to pregnancy, a CT scan due to intense occipital headaches showed displacement of the cerebellar tonsils, presuming ACM. No further evaluation was performed despite intermittent headache. The case was discussed with Neurosurgery, and disagreement between Obstetrics and Anesthesia presented in terms of type of delivery. Urgent c-section was performed under general anesthesia (GA) due to fetal bradycardia. After standard monitoring, rapid sequence induction with propofol, fentanyl, lidocaine and rocuronium was used. Laryngoscopy performed with a McCoy blade, neck in a neutral position, and intubation executed without difficulty. Surgery and awakening occurred without complications, neuromuscular blockade reversed with sugammadex. Newborn’s APGAR index was 5/10/10. The mother was hospitalized for 5 days, with no new neurological deficits or other complications. 
Discussion: The anesthetic plan for patients with ACM should include evading elevation of  ICP or changes in cranio-spinal pressure gradients. Cervical positioning may influence the position of the cerebellar tonsils, and hyperflexion or hyperextension should be avoided during airway approach.
Patients with minimal and asymptomatic cerebellar descent, the neuroaxis approach may be reasonable. However, considering that caudal cerebellar movement may occur after dura puncture with large caliber needles, it is crucial to evaluate this increased risk and, if neurological symptoms appear, act quickly.
GA allows more thorough hemodynamic control, maintaining normocapnia through invasive ventilation, thus minimizing sudden increases in intracranial pressure.
Learning Points: The challenge in the anesthetic approach to parturients with ACM is to avoid variations in intracranial or intraspinal pressure.
The airway may be an additional challenge, requiring careful placement and minimization of stimuli.
The evaluation of parturients with ACM should be done by a multidisciplinary team involving the Obstetrician, the Anesthesiologist and the Neurosurgeon.

09 / Approach to a Parturient with Arnold Chiari Malformation: A Team Controversy.