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Posterior Cervical Fusion

Anesthesia Implications
Position : Prone, arms tucked
Time : 2-4 hours (long)
Blood Loss : Low (10-50 ml)
Maintenance Paralytic : Yes
Considerations : Fluoroscopy / Xray, Arterial line, MEP monitoring, SSEP monitoring

Anesthetic Approaches

1GETT, 1/2 MAC Gas, Propofol Drip, Remifentanil Drip
2GETT, TIVA
The Anesthesia:

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.

The Pathophysiology:

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).

The Surgery:

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.