Endoscopic Posterior Cervical Discectomy & Lamino-foraminotomy
Posterior cervical disc surgery is well established and highly effective way of decompressing
the nerve root compressed by disc and bone. This was first proposed by Spurling & Scoville in 1944.
The anterior approach requires near complete disc removal, leading to premature disc space collapse.
To overcome this problem, fusion with anterior discectomy has been a standard procedure. There
is a possibility of reduction in mobility because of fusion associated acceleration of
degenerative changes at adjacent levels.
The routine posterior open approach needs large size incision to visualize the lamina, lateral mass and foramen. Severe dissection and retraction of cervical muscles for exposure causes significant postoperative pain and muscle spasm.
Reduction of approach related incisional morbidity has been clearly documented in laproscopic experience over last 2-3 decades, and natural course dictates that this technology, principle, should be extended to spinal surgical technique, and posterior cervical approach is one of the best and first.
Endoscopic foraminotomy has been shown to produce an equivalent or slightly larger decompression as compared to standard open surgery.
( Roh SW, Kim DH, Cardosci AC, Fessler RG. Endoscopic foraminotomy using MED system in cadaveric specimens. Spine. 2000; 25: 260-264.)
Unilateral disc herniations single level or two contiguous nerve root levels. This is useful for removal of posterior, foraminal acute soft discs, foraminal stenosis from osteophytic bony spurs, & facet arthropathy.
We prefer prone position over sitting position.
Patient is in prone position with neck in neutral position. Lateral fluoroscopy used to localize
the diseased level with localizing pin, so that we get the entry point in AP plane with direction
of the disc space.
The incision is paramedian centered over the foramen/ interlaminar space, measuring about 2-2.5 cms. Fascia cut and muscels separated off the midline from spinous process and lamina. Subperiosteal dissection can be achieved with osteotome. Then the outer tube of endospine fixed over lamina in between muscles latarally and spinous process medially.
Again with lateral fluoroscopy diseased level reconfirmed. The inner tube/working insert attached with the endoscope. For single level one should see the superior lamina at the cranial end, inferior lamina at the caudal end, medially the base of spinous process and laterally the facet joint in the visual field. The inferolateral margin of superior lamina & medial facet joint of the superior vertebral segment, interlaminar window with ligamentum flavum and the inferior lamina should be in the visual field. If the interlaminar window is adequate then 2mm Kerrison punch can be used to remove part of lamina so as to detach the flavum and open the space. Then laterally bone from the facet removed with micro drill diamond burr- 3mm tip. If necessary hemilaminectomy can be performed so as to have adequate decompression. The superior facet of the lower vertebral body is seen laterally below the initial laminectomy and the medially resected to access the exiting root.
Dissection of the axilla of the root usually discovers the disc herniation, or osteophyte. Disc herniation can be seen at the shoulder of the root also. Removal of the free fragment is enough for soft disc herniations and exploration of the disc space is not necessary. Osteophytes are usually not resected and large foraminotomy is more than sufficient.
Skin is closed with absorbable sutures.