P071: ANESTHETIC MANAGEMENT IN PATIENT WITH ARNOLD CHIARI MALFORMATION I
Parneet Parekh; Kendall regional Hospital
Introduction: Arnold-Chiari malformation type I (ACM I) is displacement of the cerebellar tonsils caudal to the foramen magnum. Syringomyelia is a condition in which a fluid filled cavity called a syrinx develops in the spinal cord. Here we report the anesthetic management of a case of ACM I scheduled for sub-occipital craniectomy, cervical laminectomy and duraplasty.
Methods: In the operating room patient was monitored with ASA standard monitors. Anesthesia was induced with propofol and remifentanil infusion.
Results: Patient was transferred to ICU where she was closely observed for 24 hours before being transferred to general ward. Patient’s postoperative recovery was uneventful, and she was scheduled to be discharged.
Discussion: Prevalence of Arnold-Chiari malformation is 1 per 1000 to 1 per 5000. Type I malformation is less severe and asymptomatic, but if symptoms occur, they are usually treatable. ACM I is associated with syringomyelia, hydrocephalus, and connective tissue disorders. Our patient presented with new onset of neurological symptoms with none of above associations. ACM I is associated with increased intracranial pressure (ICP). Many anesthetics lead to increased ICP, but no definitive anesthetic management has been established. Recent studies have not shown any contradiction to providing anesthesia for ACM I. Thorough preoperative examination should be performed to rule out any associated co-morbidities and appropriate steps should be taken to avoid any expected complications. Patents with ACM I are known to present with challenging airways for intubation. These patients typically present with underlying cervical fusion or scoliosis. Therefore, video laryngoscopy is recommended as opposed to direct rigid laryngoscopy.
ACM I patients present with autonomic dysfunction due to brainstem involvement of the syrinx which may prohibit the reflexive response to hypoxia, hypothermia, hypotension and hypocarbia. Our patient didn’t have any invasive blood pressure monitoring, but her temperature was closely monitored, and she was closely monitored 24 hrs. post-surgery for sudden apnea or cardiac arrest. Increased ICP is a major concern in ACM I patients. Normocapnia should be maintained to avoid any unnecessary increase in ICP. Intravenous anesthetics are advantageous in minimizing ICP elevation. We used propofol for induction in this case.
ACM I patients are more sensitive to neuromuscular blockade and use of succinylcholine should be avoided in patients with motor deficits. Succinylcholine is associated with hyperkalemia that result in denervated muscle. Our patient had normal potassium levels and had no motor deficit and succinylcholine was used during induction. Rocuronium was used to maintain procedural paralysis. She was carefully monitored with peripheral nerve twitch monitor. Patient had full recovery of motor function post-surgery.
In conclusion, ACM I patients can present a challenge for the anesthesiologist, thus far there has not been an established protocol for these patients. Careful preoperative management and consultation with neurosurgery, neurology, and intensive care is vital to optimizing outcomes.