103 - Enhanced Recovery After Surgery (ERAS) Protocol for Chiari Malformation Type 1(CM1) Using MIS and Intraoperative Ultrasound

Introduction: ERAS pathways have been shown to help reduce complications, improve outcomes and reduce cost. Currently there are no reported ERAS pathways directed at CM1. We are the first to describe an ERAS pathway for CM1 using minimally invasive surgery (MIS) and Intraoperative ultrasound (US).
Material and

Methods:
One hundred thirty-one patients with CMI were operated on by a single surgeon from 1999-2021. Ninety-eight patients underwent traditional suboccipital craniectomies with cervical laminectomy and duraplasty. Thirty three patients followed an ERAS pathway we developed for CM1 which incorporated a MIS approach and intraoperative US to avoid dural opening. Among those thirty-three patients, twenty three of these patients had a traditional mini-open approach. The remaining 10 patients had surgery using a minimally invasive retractor system. Our Chiari ERAS pathway incorporated preoperative, intraoperative and postoperative elements which will be described.
We compared patients utilizing a traditional surgical approach versus those undergoing our ERAS pathway as it pertained to length of surgery, hospital length of stay (LOS), CSF related complications, and outcomes with a reduction of symptoms. All patients were followed for a minimum of one year.
Surgical Technique:
All patients were positioned prone with the head fixated. A 1.5cm incision was made over the C1 lamina, a guide needle was carefully docked on the midline of C1 lamina or inferior occipital skull. Careful serial dilation over the wire was performed under continuous fluoroscopy until a 18mm working tube was attached into place. Dissection of muscle off the suboccipital skull and C1 lamina using an extended monopolar cautery. The working tube was angled as needed to complete the drilling and bone removal. Intraoperative ultrasonography confirmed adequate tonsillar decompression and CSF flow velocities after atlanto-occipital ligamentous bands are released from the underlying dura. Our cut off was 3 / s of CSF velocity thru the fourth ventricle. If adequate decompression and good CSF flow is observed the dura was not opened. The wound closed in multiple layers to provide a water-tight closure. Chicago Chiari Outcome Scale was used postoperatively to access patients. All patients were followed for a least one year.

Results: All ERAS patients had a significant reduction of headaches and sensorimotor preoperative symptoms and findings. All patients remained symptom free at one year. No patients required reoperation for additional decompression. The average length of stay was 3.1 days for patients who had duraplasties, 1.1 days for the non-duraplasty group. Length of surgery for the duraplasty group was 118 minutes compared to 77 minutes and 64 minutes for the non-duraplasty group using open and minimally invasive approach respectively. The duraplasty group experienced complications which included 10 pseudomeningocoeles, but none required reoperation. Three delayed incisional CSF leaks which were treated with over sewing the incision and lumbar drain. The non-duraplasty group had no complications. ERAS pathway patients saved an average of $8000/ case.

Conclusion: Utilization of ERAS pathways for CMI can significantly improve outcomes and reduce surgical costs.