Anterior Endoscopic Cervical Microdecompression of Disc and Foramen

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Chapter 22 Anterior endoscopic cervical microdecompression of disc and foramen

John Chiu, MD

The standard treatment for cervical disc protrusions and foraminal stenosis ha s been anterior cervical microdecompression of the disc and foramen with or without bony fusion [1–5]. These open operations are associated with significant local morbidity [6,7], such as graft collapse, graft extrusion, hardware failure, nonfusion with resultant instability, infections, esophageal perforation with infection, and permanent pain, peripheral nerve injury, or infection at the graft donor site. Anterior cervical fusion (ACF) is associated with a 15% or greater chance of junctional disc herniation or adjacent segment disease at interspaces adjacent to fused levels [8,9].

The evolution of spinal surgery is trending toward less invasive techniques [9–16]. Advancements in microinstrumentation, fiberoptics, improved fluoroscopic imaging, and high-resolution digital video imaging endoscopy, along with the accumulation of experience in percutaneous lumbar discectomy [17–20] and spinal laser applications [20–23], have facilitated the development of anterior endoscopic cervical microdecompression (AECM) and foraminal decompression [9,14,19]. AECM, as minimally invasive surgery, does not affect the stability of adjacent vertebral segments [8–10]. Although ACF is often an unattractive treatment for patients with multiple-level disc symptoms, AECM can be safely utilized for treatment of such patients.

Treatment objectives

The primary objective of AECM is to perform decompression of the herniated cervical disc and foraminal disc. It is a minimally invasive outpatient procedure that aims to reduce tissue trauma with much less morbidity than open cervical spinal surgery [9,10,12]. There is no graft donor site to cause secondary problems, and the period of convalescence and the costs of the procedure are significantly less than those of traditional open operations.

Indications

The indications for AECM are as follows [9,12,19]:

image Symptomatic herniated cervical disc and foraminal disc lesion
image Subjective complaints of neck pain with radiation down the arm (radicular pain)
image Symptoms of tingling and numbness
image Physical findings of sensory loss, muscle weakness, and/or decreased reflexes in the upper extremities that correlate with the level of involvement
image Severe intractable cervicogenic headache associated with neck pain
image No improvement of symptoms after a minimum of 12 weeks of conservative therapy
image Magnetic resonance imaging (the imaging study of choice) or computed tomography findings of disc herniation consistent with the dermatome of clinical symptoms
image Junctional disc herniation syndrome (JDHS) or adjacent segmental disease (ASD) in patients who have undergone cervical fusion
image Positive preoperative or intraoperative discogram and pain provocation test results
image A positive electromyography result can be an indication if other indications are present

Contraindications

Contraindications to AECM are as follows [9,12]:

image Imaging study showing severe cervical spinal canal stenosis.
image Significant migration of a free disc fragment, which is therefore not located at disc level.
image Advanced spondylosis (significant bone spurs) with severe disc space narrowing and with osteophytes blocking entry into the disc space.
image Significant ossification of the posterior longitudinal ligament.

Advantages

The advantages of AECM in comparison with open procedures are as follows [8,9,12,19,22]:

image Excellent pain relief
image Same-day outpatient procedure without need for hospitalization
image Small incision and less scarring of the neck
image No dissection of muscle, bone, ligaments, or manipulation of the dural sac or nerve roots; little or no epidural bleeding
image Does not promote further instability of spinal segments, and preserves spinal motion
image Allows early return of patients to usual activities, including work
image Is commonly performed with the use of local anesthesia
image Costs much less than conventional discectomy and spinal fusion
image Makes multiple-level discectomy feasible and well tolerated
image Is least challenging to medically high-risk patients and the obese
image Allows patients to begin basic exercise programs the same day as surgery
image Is less traumatic, both physically and psychologically

Instrumentation

The following instruments and equipment are needed for AECM (Fig. 22-1) [9,12]:

image Endoscopic tower equipped with digital video monitor, DVT/VHS recorder, light source, photo printer, and tri-chip digital camera system.
image Cervical endoscopic discectomy set (Karl Storz, Tuttlingen, Germany), including 4-mm, 0-degree endoscope.
image Cervical discectomy sets (2.5 and 3.5 mm) (Blackstone Medical, Inc., Springfield, MA) with short cervical discectomes.
image 3.5-mm, 6-degree cervical operating endoscope.
image Endoscopic grasping and cutting forceps.
image Endoscopic probe, knife, rasp, and bur.
image More aggressively toothed trephines used for spurs and spondylitic ridges at the anterior and posterior disc space.
image Holmium:yttrium-aluminum-garnet (Ho:YAG) laser generator (Trimedyne, Inc., Irvine, CA) with right-angle (side-firing) probe (Fig. 22-2).
image Digital fluoroscopy equipment (C-arm) and monitor.
image

Figure 22–1 Video digital endoscopy tower and anterior cervical endoscopic instruments (Karl Storz, Tuttlingen, Germany). (A) Cervical 0-degree endoscopes and endoscopic instruments. (B) Discectomes, working channel sets. (C) Discectomy set: forceps, trephines, and bur. (D) Tri-chip digital camera with cervical 6-degree endoscope and forceps. (E) Video digital endoscopic tower.

image image

Figure 22–2 Holmium:yttrium-aluminum-garnet laser equipment (Trimedyne, Inc., Irvine, CA) for laser thermodiscoplasty. The laser generator (A) and right-angle (side-firing) laser probe (B).

Procedure

Anesthesia

image Local anesthesia with monitored intravenous conscious sedation is used for AECM.
image General anesthesia may be used for restless patients.
image Intravenous injection of 2.0 g cefazolin and 8.0 mg dexamethasone are routinely given.
image The esophagus is made more palpable by insertion of an esophageal or nasogastric tube.
image The pulse of the carotid artery may be augmented with sympathomimetics (e.g., ephedrine) to raise systolic blood pressure to a minimum of 130 mm Hg.

Patient Positioning

Figure 22-3

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