Cervical Laminoplasty

Illustrative Case

A 70-year-old woman with painless progressive cervical myelopathy. X-ray demonstrates preserved lordotic alignment. MRI demonstrates multilevel severe cord compression C3-7 (Figure 4-1).

Figure 4-1

Figure 4-1 ▪ (continued)

Radiologic Assessment

The ideal indications for laminoplasty are in the patient with multilevel myelopathy, preserved lordosis on upright lateral x-ray, no significant instability, and minimal generalized axial pain.
- K-line should be positive, meaning that a dorsal decompression not only is likely to relieve any dorsal cord compression but also allows the cord to drift sufficiently away from any anterior compression.
Scrutinize the preoperative MRI for the extent of cord compression to determine the proximal and distal extent of laminoplasty necessary for adequate decompression.
- Imagine the amount of cord “drift-back” that laminoplasty will allow by looking at a mid-sagittal T2-MRI.
- The majority of patients who are good candidates for laminoplasty require laminoplasty of C4, C5, and C6, along with a laminectomy of C3 for sufficient cord decompression. This will allow for decompression spanning from the C2-3 to C6-7 disk levels.
- Imagine whether additional laminectomy of C2 is needed to decompress proximal to the C2-3 disk level (rare), or to allow for further cord drift-back.
- Identify any symptomatic foraminal stenosis that may require additional foraminotomy.

Positioning

Patient is positioned prone on a regular OR table with Mayfield head holder and chest bolsters (Figures 4-2 and 4-3).

Ensure there is a long draw sheet under the patient to tuck arms by the patient’s side.

Abdomen should be as free as possible to reduce venous bleeding and prevent ventilatory difficulty.

Figure 4-2 ▪ Bed setup for laminoplasty.

Figure 4-3 ▪ Properly positioned patient for laminoplasty. The bed is in reverse Trendelenburg, the neck is in neutral to slightly flexed alignment, and the overall alignment of the neck is roughly horizontal/parallel to the floor.

Foam padding is placed around the exposed aspect of each arm; the IV tubing and leads are kept on the outside of the foam padding to avoid any pressure points on the skin.
Arms are tucked using the long draw sheet that is brought over the foam padding crossed over the low thoracic levels on patient’s back and secured with penetrating towel clamps. Ensure that IVs and/or A-line is still functional.
Table is placed in reverse Trendelenburg in order to have the cervical spine roughly parallel to the ground once finally positioned.
- The “leg up” button is used to flex the knees and prevent the patient from sliding caudally or generating excessive cervical traction because of the body weight vector pulling caudally.
- Having the cervical spine elevated reduces venous bleeding.
  - Avoid a “head down” position, which makes surgery more difficult and increases venous bleeding.
Mayfield head holder is adjusted as needed to achieve neutral to slight flexion alignment and chin tuck.
- Ideally, when the patient is positioned, the neck should be roughly parallel to the floor when viewed sagittally.
- Having a slight amount of flexion facilitates laminoplasty by reducing the “shingling” or overlap of the cephalad lamina on the caudal lamina. This makes the surgery easier to perform.
- Preoperatively, assess the amount of extension tolerated by the patient without exacerbation of neurologic symptoms to avoid placing the cord in that position.
If necessary for lateral fluoroscopic visualization, the shoulders are gently taped down starting at the lateral acromion, with the tape attached to the distal end of the table.
- Take care when taping the shoulders to avoid excessive traction, which can potentially cause loss of neuromonitoring signals or, worse, true neurologic injury.

Anesthesia and Neuromonitoring Concerns

Anesthetist should be aware that the patient is myelopathic and that intubation should proceed avoiding excessive extension.
- At Emory, we request that anesthetist perform video-assisted intubation using a camera on the end of the laryngoscope.
  - This tool allows for intubation essentially without the need for any cervical extension.
  - As a result, fiberoptic intubation is rarely needed.
It is important to maintain mean arterial pressure in myelopathic patients to ensure adequate cord perfusion throughout the entire operation.
- We generally use somatosensory evoked potential neuromonitoring for laminoplasty because it does not involve a deformity correction or a change in alignment of the spine. Refer to the chapter on neuromonitoring for further details.
  - In contrast, cases involving deformity correction or realignment (eg, osteotomy) are performed with additional motor evoked potentials because of their greater sensitivity.

Localization of Incision

X-ray is generally not necessary to localize this incision. Palpate the prominent C2 and C7 spinous processes to aid in estimating the cranial and caudal extent of the incision.

Approach

The skin is incised with a No. 10 blade through the dermis, and hemostasis is achieved with unipolar electrocautery.
The avascular median raphe is identified and the dissection is taken down to the tips of the spinous processes. C2 and C7 are the most prominent and easily palpable.
Once the tips of the spinous processes have been identified, a clamp or needle is applied to the cephalad-most spinous process and a lateral cross-table x-ray is obtained for localization.
- This is done before proceeding deeper, to avoid inadvertently detaching C2 muscle insertions.
Electrocautery is then used to perform a subperiosteal dissection to expose the desired lamina. Careful attention should be paid to stay in the midline avascular plane to reduce bleeding.

Exposure should extend just lateral to the lateral mass-laminar junction bilaterally (Figure 4-4).

The plated side will generally require slightly more lateral exposure in order to accommodate the plate.

Figure 4-4 ▪ Completed exposure for laminoplasty C4-6 with laminectomy C3. Note that the attachments onto C2 are completely left intact. The proximal attachments on C7 are detached, but nothing distal. Lateral exposure need go no further than the lateral mass-laminar junction.

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