Posterior Cervical Fusion

Anesthesia Implications

Position: Prone, arms tucked
Time: 2-4 hours (long)
Blood Loss: Low (10-50 ml)
Post-op Pain: Moderate (3-6)
Maintenance Paralytic: Yes
Lead: Yes

Limited Range of Motion (ROM) – Most of these patients have very limited neck mobility, or have a a previous cervical injury, so assess the patient’s cervical range of motion. Generally, a video laryngoscope of some kind is recommended to facilitate minimal neck flexion during intubation.

Pre-existing nerve damage/dysfunction – Carefully assess and document pre-existing weakness or paresthesias.

Approach – Communicate with the surgeon early. If he/she is planning on neuro-monitoring intra-operatively, Total IV Anesthesia (TIVA) should be used. TIVA example: Propofol 100-120 mcg/kg/min, Remifentanyl 0.15-0.2 mcg/kg/min, Neosynepherine gtt if needed for BP maintenance.

Arterial line – Arterial line is recommended to continuously monitor BP.

Large-bore IV’s – You’ll need at least 2 20g IVs (or larger).

Secure the ETT – Make sure that ETT is properly secured as the patient will be in the prone position.

Mayfield pins – If Mayfield pins are used to secure the head for surgery, it is recommended to give a dose of propofol (50-100mg) 1-2 min before pin placement.

Proning the patient – Log-roll patient with head and neck neutral at all times. Make sure IV tubing has enough slack, or temporarily disconnect while turning. Also disconnect ETT from the circuit and ventilator while rolling to avoid any pulling on the tube. Reconnect circuit and monitors ASAP and check tube placement by listening to breath sounds bilaterally.

Emergence – Patient will be rolled back to the supine position, and a collar is often applied (especially if this is being performed for a fracture). Deep extubation is recommended, if not contraindicated, to prevent coughing. Some surgeons request systolic blood pressure to be less than 140 mmHg after extubation.

Tucked Arms (general considerations): Consider a second IV – once the procedure has started, it’s going to be VERY difficult to handle IV issues – especially if your only IV has problems. Ensure the IV is running and monitors are still functioning after tucking the patient’s arms

Prone Position (general considerations): Maintain cervical neutrality. Keep IV’s out of the antecubital space. The patients arms are typically flexed, which will kink the IV. Eye protection should be used as the prone position heightens the risk of corneal abrasion and/or traction on the globe (which can result in blindness). Check the patients eyes/ears/nose regularly throughout the case to ensure they are free of pressure. Positioning of the leads is typically high on the posterior and posterolateral back (somewhere free of pressure and out of surgical borders). Keep your connections and tubing where you’ll have fast access.

Long procedure (general considerations): Procedures anticipated to last longer than 2 hours generally require a urinary catheter. Also consider checking lines and positioning regularly as the risks of infiltration and nerve damage are increased with procedure time. Consider an IV fluid warmer and a forced air warmer to keep the patient euthermic.

Fluoroscopy / Xray (general considerations): Have lead aprons and thyroid shields available. Alternatively, distancing yourself 3 to 6 feet will reduce scatter radiation to 0.1% to 0.025% respectively. Occupational maximum exposure to radiation should be limited to a maximum average of 20 Sv (joules per kilogram – otherwise known as the Sievert/Sv) per year over a 5 year period. Limits should never exceed 50 Sv in a single year.

Arterial line (general considerations): Preoperatively check pulses to gauge the best side to attempt the A-line. Perform an Allen test to ensure adequate blood flow. Have the A-line equipment set up and ready in the room.

MEPs (general considerations): Most commonly, anything above the cauda equina (T1/T2) will be MEP and SSEP monitored in spinal cases. Long-term paralytics are normally contraindicated. Short term paralytics (eg succinylcholine) may be used for intubation. Some surgeons will prefer complete TIVA (eg. a common combination is propofol 25-150 mcg/kg/min, remifentanil 0.125-1.0 mcg/kg/min), while others are fine with 1/2 MAC of gas and a propofol drip. Ask the surgeon. Additional equipment needed: bite block, BIS monitor (if using TIVA).

The most common reason for this procedure is cervical spondylotic myelopathy (CSM). CSM is defined as arthritic changes in the cervical spine due to ossification of the ligaments or disk disease, which results in neurologic changes due to compression of the spinal cord. CSM typically can present as weakness in all four extremities, but is most commonly presented as weakness in the upper extremities. Posterior Cervical Fusion is indicated for patients with CSM, severe stenosis and/or myopathy due to a tumor, infection, or cervical injury (fracture or dislocation).

As suggested by the name, the surgery is performed from the posterior side. A straight midline incision will be made from the base of the head along the posterior side of the neck. Dissection is performed, removing all tissues (including muscle and bone) until the spinal cord is exposed at the appropriate levels. Decompression of the spinal cord is followed by fusion using screws, rods, grafts, and implants.

Depending on the site of compression, removal of the lamina as well as removal of bone spurs may be performed where the nerve roots exit the spinal canal.

Closure is done in layers. Vancomycin powder is used during closure to prevent infection.