Biportal Endoscopic Posterior Cervical Foraminotomy.

Abstract

Background: Cervical spine pathologies causing nerve-root compression are treated with use of decompression through a variety of techniques. Although several operative management options exist, cervical foraminotomy may be indicated in patients with isolated, unilateral cervical radiculopathy. Biportal endoscopic cervical foraminotomy allows decompression with minimal soft-tissue disturbance and excellent visualization.

Description: The procedure is performed with the patient in a prone position with routine neuromonitoring. Intraoperative fluoroscopy is utilized to identify the operative level, and 2 paramedian incisions are made for the portal sites at a 20° to 30° angle to the desired disc space. The working portal is utilized for surgical instruments, and the second portal serves as a viewing portal for the endoscope. Sequential dilators are utilized to establish the working portal, and a semi-tubular sheath of the desired length is placed. For the viewing portal, an endoscopic trocar is advanced through the fascia, and the camera is introduced. After endoscope insertion, surgical landmarks are identified, beginning with the interlaminar V point that marks the junction of adjacent laminae at the medial border of the facet joint. Once identified, overlying soft tissue is removed using radiofrequency ablation, and decompression of the nerve root can begin. We alternate between utilizing a high-speed diamond burr and a Kerrison rongeur to perform a laminoforaminotomy. Care is taken to minimize the facetectomy extent to <50% in order to reduce the risk of iatrogenic instability. The ligamentum flavum is preserved until the end in order to protect the dura from fluid pressure and surgical instruments. In the presence of disc herniation, disc fragments are removed through the working portal after gentle nerve root retraction. Once decompression of the neural foramen is completed to the lateral border of the pedicle, meticulous hemostasis is achieved using radiofrequency ablation, bone wax, and flowable thrombin-based hemostatic agents. Patients are typically discharged home on the same day.

Alternatives: Patients can undergo cervical foraminotomy utilizing traditional open, microscopic tubular, or uniportal endoscopic techniques. Alternatively, patients may undergo anterior cervical discectomy and fusion (ACDF) or cervical disc arthroplasty (CDA), according to surgeon preference and individual patient pathology.

Rationale: Both open and minimally invasive cervical foraminotomy result in favorable clinical outcomes^1,2. However, minimally invasive approaches are associated with earlier discharge, and reduced muscle damage and operative blood loss. Although tubular foraminotomy is a traditional minimally invasive option, endoscopic approaches offer distinct benefits. First, biportal endoscopy allows for greater maneuverability and visualization of the neural foramen. Second, compared with ACDF and CDA, foraminotomy obviates the need for instrumentation, preserves segmental motion, and avoids the anterior approach, which is associated with dysphagia, dysphonia, and potential for vascular injury.

Expected outcomes: Ruetten et al. conducted a randomized controlled trial comparing endoscopic cervical posterior foraminotomy to traditional microsurgical foraminotomy³. In that study, 87.4% of patients experienced complete resolution of their arm pain, although there were no differences in clinical outcomes, complication rates, or revision rates between treatment groups. Most evidence regarding the role of endoscopic cervical foraminotomy remains low-quality; however, meta-analyses have reported high clinical success, with 91% to 94.9% of patients demonstrating good-to-excellent clinical outcomes^2,4,5. A separate meta-analysis of prospective trials showed similar clinical outcomes between endoscopic foraminotomy and ACDF for cervical radiculopathy but a significantly shorter perioperative hospitalization time with endoscopic foraminotomy⁶. When broadly comparing minimally invasive foraminotomy to open foraminotomy, patients undergoing minimally invasive foraminotomy experienced reduced blood loss (52.8 versus 173.5 mL), operative duration (58 versus 108 min), and inpatient narcotic use (2.5 versus 27.6 milligram morphine equivalents)¹.

Important tips: Achieve adequate endoscopic visualization before starting osseous resection.Avoid inserting instruments blindly into the interlaminar space.Complete removal of the medial superior articular process up to the lateral border of the pedicle.Ensure palpation of the lateral aspect of the cranial and caudal pedicles.Inspect for extruded disc material.Maintain the ligamentum flavum until the end of the decompression.Achieve hemostasis to prevent postoperative epidural hematoma.

Acronyms and abbreviations: NSAID = nonsteroidal anti-inflammatory drugACDF = anterior cervical discectomy and fusionCDA = cervical disc arthroplastyESI = epidural steroid injectionRFA = radiofrequency ablation.