Posterior Tubular Endoscopic Cervical Laminectomy and Foraminotomy

50 Posterior Tubular Endoscopic Cervical Laminectomy and Foraminotomy

Albert P. Wong, Youssef J. Hamade, Zachary A. Smith, Nader S. Dahdaleh, and Richard G. Fessler

50.1 Introduction

Cervical spondylosis is a degenerative spinal condition that can result in progressive foraminal or central stenosis of the spine, leading to radiculopathy or cervical spondylotic myelopathy.1,2,3 A minimally invasive posterior cervical approach through a tubular retractor may maximize the benefits of surgical decompression while minimizing soft-tissue trauma, resulting in improved neurologic outcomes with a decrease in surgical morbidity or spinal instability.^{4,5,6,7,8,9,10,11} This chapter describes the surgical technique for a posterior cervical minimally invasive microendoscopic foraminotomy (cMEF) and laminectomy (cMEL) (Video 50.1).

50.2 Patient Selection

Prior to surgical intervention, a thorough history and physical examination, with review of pertinent imaging (X-rays or MRI of the cervical spine), is always completed. Any ambiguity in the surgical level may be clarified with adjunctive tests: nerve conduction studies (NCS), electromyography (EMG), and selective nerve root blocks may be helpful in confirming the level of the pathologic nerve root.^{12,13,14,15,16}

50.2.1 Indications

• Upper-extremity weakness, pain, numbness, or tingling (cMEF)^17,18

• Radiographic evidence of cervical foraminal stenosis correlating with clinical presentation without spinal cord compression (cMEF)

• Clinical signs or symptoms of spinal cord compression (cMEL)

• Radiographic evidence of cervical spinal cord compression primarily from dorsal pathology, such as hypertrophic ligamentum flavum or hypertrophic facets (cMEL)

50.2.2 Contraindications

• Axial neck pain as the primary complaint with minimal upper-extremity symptoms (cMEF or cMEL)¹⁸

• Trauma patient with cervical spine fractures (cMEF or cMEL)

• Cervical instability based on dynamic flexion–extension X-rays (cMEL)

• Radiographic evidence of cervical spinal cord compression primarily from ventral pathology, such as a central disk herniation, osteomyelitis, tumor, ossified posterior longitudinal ligament (OPLL), or cervical kyphosis (cMEL)

50.3 Surgical Technique

Note that setup is the same for cMEF and cMEL.

50.3.1 Positioning

• The patient may be placed in either the prone or the sitting position with the head secured by a three-point pin fixation system. The sitting position allows the operative blood to drain away from the surgical field.

• Neuromonitoring may be used to decrease the risk of potential neurologic injury.

• The surgical level is marked with lateral fluoroscopy.

• The entry point is 1.5 cm lateral to the midline. The incision is ~ 18 mm long.

• Skin infiltration is done with local anesthetic (1% lidocaine).

50.3.2 Surgical Approach

See Fig. 50.1 through Fig. 50.13 and Video 50.1.

• The skin is incised with a scalpel and electrocautery is used to dissect through the posterior cervical fascia until the muscle fibers are exposed.

• Blunt scissors are used to gently separate the muscle fibers, while the index finger may be used to bluntly dissect the surgical planes until the laminofacet junction is palpated.

• The smallest tubular dilator is guided onto the laminofacet junction with the index finger and the surgical level confirmed with fluoroscopy.

• Sequential tubular dilators are used to bluntly separate the muscle fibers in a nontraumatic fashion until the final tubular retractor is secured with a robotic arm.

50.3.3 Microendoscopic Foraminotomy

• Residual soft tissue overlying the ipsilateral laminofacet junction is removed with a combination of electrocautery and pituitary rongeurs.

• A high-speed drill and Kerrison rongeurs are used to perform a limited ipsilateral laminotomy and medical facetectomy.

• One-third to one-half of the medial inferior and superior articular processes of the surgical level may be removed until the “shoulder” of the nerve root is clearly exposed.

• Residual ligamentum flavum is removed with rongeurs until the nerve root is completely mobile.

50.3.4 Microendoscopic Laminotomy

• Once the ipsilateral laminectomy and facetectomy are completed, the cMEL procedure continues with decompression of the contralateral lamina and ligament.

• The endoscope is repositioned medially to visualize the ventral surface of the spinous process and contralateral lamina.

• A high-speed drill with a guarded drill tip is used to undercut the ventral surface of the spinous process and contralateral lamina.

• The bony resection is continued until the contralateral foramen is visualized or palpated with a bayoneted Penfield-4.

• Kerrison rongeurs may be used to complete the bony decompression.

• Fluoroscopy may be used to confirm entrance into the contralateral foramen.

• Once the bony decompression is complete, the contralateral ligamentum flavum is removed with rongeurs.

• After the contralateral ligamentum flavum is removed, the endoscope is repositioned to remove the residual ipsilateral ligamentum flavum.

• Hemostasis is achieved with electrocautery and thrombin-soaked agents.

• The tubular retractor is removed and soft-tissue bleeding is coagulated under direct visualization.

• The fascia is approximated with absorbable sutures, and the dermis is closed with a skin adhesive.

Fig. 50.1 (a,b,c) Drawing of a paracentral cervical disk herniation with compression of the traversing nerve root. T2-MRI axial and sagittal views demonstrate moderate central and lateral recess stenosis treatable with a minimally invasive posterior laminotomy/foraminotomy.