Endoscopic Posterior Cervical Foraminotomy and Discectomy.

Background: Open posterior cervical foraminotomy has been shown to be comparable with anterior cervical discectomy and fusion (ACDF) in the treatment of cervical radiculopathy^1,2. More recently, posterior endoscopic cervical foraminotomy was described as an ultra-minimally invasive technique that allows for neural decompression in cervical radiculopathy. This technique has been shown to have excellent clinical outcomes with a short length of hospital stay and low postoperative pain levels³.

Description: The procedure is performed with the patient in the prone position under general anesthesia. Fluoroscopy is utilized to mark out the incision and target the medial-most aspect of the facet at the level of foraminal stenosis. Sequential dilators are then inserted to create a working canal, and the endoscope is introduced. Soft tissue is cleared until the classic "V" interlaminar anatomic landmark is visualized. The superior edge of the cephalad lamina and the inferior articular process are resected until the superior articular process is identified. The superior articular process is then thinned out with use of a diamond burr and resected carefully with use of a Kerrison punch, allowing visualization of the nerve beneath. Decompression should be wide, carried out from pedicle to pedicle and as laterally as required. A discectomy may be performed at this stage.

Alternatives: Alternatives include open posterior cervical foraminotomy, ACDF, and cervical disc arthroplasty.

Rationale: In the case of isolated cervical radiculopathy, the pathology is limited to the foramen. The foramen may be approached either anteriorly or posteriorly. However, in order to successfully address the foramen anteriorly, a complete discectomy should be performed. In such cases, either a fusion or disc arthroplasty should be performed concurrently with the discectomy. Both fusion and disc arthroplasty are associated with complications such as adjacent segment degeneration, implant subsidence, infection, nonunion, and others⁴. Posterior foraminotomy allows for successful neural decompression posteriorly, but when performed in an open fashion it requires substantial soft-tissue dissection for an appropriate exposure, which may result in notable postoperative neck pain. Posterior endoscopic cervical foraminotomy addresses many of these shortcomings because it allows for successful neural decompression through an endoscope, with minimal soft-tissue dissection; maintains range of motion; and preserves most of the disc at that level⁴. Furthermore, this technique does not preclude or complicate the ability to perform a full discectomy anteriorly in the future, if needed.

Expected outcomes: Endoscopic posterior cervical foraminotomy has been shown to have excellent clinical outcomes; however, as with any spinal surgery, it carries a risk of complications. Kim et al. compared outcomes between uniportal endoscopic cervical foraminotomy, biportal endoscopic cervical foraminotomy, and tubular cervical foraminotomy. All 3 techniques demonstrated similar outcomes at 1 month in terms of pain improvement; however, length of hospital stay and overall complication rates were lowest in the uniportal endoscopy group⁵. In a recent meta-analysis, Guo et al. compared endoscopic cervical foraminotomy and ACDF for the treatment of cervical radiculopathy. Postoperative pain, symptom resolution, and complication rates were similar between procedures. The most common complications were cage subsidence and dysphagia for ACDF compared with nerve root palsy for endoscopic foraminotomy⁶.

Important tips: Dropping your hands medially allows for undercutting of the inferior articular process, maximizing foraminal expansion while preserving as much facet joint as possible. At least 50% of the facet joint should be maintained in order to avoid iatrogenic instability.To improve hemostasis, transiently increase fluid pressure by obstructing fluid outflow or advancing the endoscope. Pump pressure settings can also be temporarily increased if needed; however, care must be taken not to compromise intrathecal circulation or elevate intracranial pressure.Pulling disc fragments straight out frequently results in fragmentation. Instead, we recommend maintaining a gentle grasp and utilizing a twisting motion to extract disc herniations in the case of larger fragments.Understand the learning curve for performing posterior endoscopic cervical foraminotomy and plan accordingly for case duration⁶.

Acronyms and abbreviations: PECF = posterior endoscopic cervical foraminotomyLOS = length of stayIAP = inferior articular processSAP = superior articular processNSAID = nonsteroidal anti-Inflammatory drugMRI = magnetic resonance imagingOR = operating roomAP = anteroposteriorVAS = visual analog scaleUPE = uniportal endoscopyBP = biportal endoscopy.