Foraminotomy – Indications, Procedure, Technique

Step 1: Position of the Patient

Place the patient in a prone position on a Jackson table with 6 posts and with the head resting comfortably on a soft facial pillow, and tape the shoulders down to provide traction to the skin and help with fluoroscopic visualization of the lower cervical? levels.

• Place the patient prone on a radiolucent Jackson or Allen table that has the ability to rotate.
• Two posts are used to support the chest, 2 are at the iliac crest, and 2 are over the proximal part of the thighs.
• Place the head comfortably on a soft facial pillow. We use a padded Mizuho ProneView protective helmet.
• Alternatively, use Mayfield skull traction or a horseshoe head holder to position the head.
• Place the head of the patient in gentle flexion to decrease the cervical? lordosis. Flexion is achieved by maintaining the chest pads low on the chest to allow for natural flexion of the neck.
• Place the bed in a reverse Trendelenburg position to help with intraoperative bleeding.
• Use surgical tape to lower the shoulders and facilitate imaging of lower cervical levels .
• Intraoperative photograph with the patient in the prone position and the shoulders taped to facilitate exposure.
• Make a lateral cervical radiograph with a metallic marker used to confirm the correct operative leve.
• For the lower cervical levels, visualization on a true lateral radiograph can sometimes be difficult. An off-axis lateral radiograph can be used to help identify the correct level when a true lateral radiograph is inconclusive.

Step 2: Perform the Skin Incision

Make the skin incision adjacent to the spinous process on the side of the abnormality over the operative level.

• Make a longitudinal 14-mm incision adjacent to the spinous process on the side of the pathological condition. This incision is immediately adjacent to the spinous process and is generally within 2 mm of the lateral aspect of the spinous process.
• Introduce the initial dilator through the skin incision and advance to the inferomedial edge of the rostral lateral mass at the operative level.
• Use lateral fluoroscopy to confirm the level.
• Release the deep cervical fascia with a knife or Bovie electrocautery to enable passage of the tubular dilators.

Step 3: Use Tubular Dilators to Make a Working Portal

Use sequential dilators to create a working portal and secure the working tube overlying the lamina-facet junction of the operative level.

• Use sequential dilators to create a working portal within the soft tissues.
• Center the final working tube over the lateral aspect of the lamina and medial facet joint of the appropriate operative level. It is our preference to use a 14-mm-diameter tube.
• Secure the working tube to a sterile arm that is attached to the bed.
• Use lateral fluoroscopy to confirm the level.

Step 4: Perform the Laminoforaminotomy

Perform the laminoforaminotomy with the use of a high-speed drill and a Kerrison rongeur to create a working window into the foramen.

• Remove any remaining muscle overlying the bone with a pituitary rongeur.
• Start the laminoforaminotomy under microscopic visualization using a high-speed burr. We prefer a side-cutting matchstick burr tip so that we can aggressively remove bone without placing the neurologic structures at increased risk.
• The assistant surgeon provides irrigation while the primary surgeon is burring.
• Begin at the junction of the lamina and facet with an even amount of the cranial and caudal lamina removed, starting medially and working laterally toward the facet joints.
• Identify the medial and cephalad margins of the pedicle to orient with respect to the neural foramen.
• Continue the foraminotomy until the lateral margin of the pedicle begins to fall away, at which point approximately one-third to one-half of the medial facet should have been removed.
• A small laminotomy in the caudal lamina can be used to improve visualization of the nerve root.
• Address epidural bleeding, which is generally encountered, with either powdered Gelfoam (Pfizer) with thrombin or bipolar cautery. Bipolar cautery can be used with readily identifiable and discrete bleeders. Care should be taken to avoid cautery directly on the neural structures.

Step 5: Perform the Foraminal Decompression

Use a nerve hook to superiorly retract the nerve root, and perform a discectomy and decompression.

• Use a curet or nerve hook to identify the proximal border of the caudal pedicle. In order to perform a complete foraminal decompression, the nerve must be decompressed fully from the medial to the lateral border of the caudal pedicle.
• Once the top of the pedicle is identified, use a nerve hook to assess how “tight” the foramen is.
• Use a 2-mm Kerrison punch to remove bone until the amount of osseous resection and the room available to the nerve are satisfactory.
• Gently retract the nerve superiorly with a nerve hook to identify any disc fragments.
• Remove any visible, loose disc fragments with a micro-pituitary rongeur.
• Contained disc fragments require an incision of the posterior longitudinal ligament.
• Use reverse-angled curets and angled micro-pituitary rongeurs, also known as down-going pituitaries, to facilitate the removal of the disc herniation.
• Remove foraminal osteophytes with the use of a Kerrison rongeur.
• Control bleeding with powdered Gelfoam and bipolar cautery.

Step 6: Wound Closure and Postoperative Care

Obtain hemostasis with electrocautery or hemostatic foam and close the wound with a standard layered closure.

• Copiously irrigate the wound with normal saline solution.
• Obtain hemostasis with electrocautery or hemostatic foam.
• Reapproximate the deep cervical fascia. We place 1 stitch using a UR-6 needle and 1 Vicryl suture so as to not overtighten the muscle.
• Close the wound with a subcuticular 4-0 Vicryl suture (Ethicon). Dermabond (Ethicon) can then be applied to the wound.
• Apply a sterile dressing.
• We do not routinely manage patients with a soft collar postoperatively.
• Patients are encouraged to perform a normal range of motion without restriction.
• Patients are seen in the office six weeks from their date of surgery and, if they are doing well, are released to full activity at that time.

Before the Procedure

What happens during a foraminotomy?

Your doctor can help explain the details of your particular surgery. (The following outlines a minimally invasive type of foraminotomy. Incisions are wider in a traditional foraminotomy.) A neurosurgeon and a team of specialized nurses and healthcare professionals will perform the surgery. The whole surgery will take a couple of hours. In general, you can expect the following:

• During the procedure, you’ll lie on your stomach.
• You will be given medicine (anesthesia) to put you to sleep through the surgery. You won’t feel any pain or discomfort during the procedure.
• Someone will carefully monitor your vital signs, like your heart rate and blood pressure, during the surgery.
• Your surgeon will make a small incision just beside your spine on the side you have your symptoms. He or she will make the incision at the level of your affected vertebra.
• Your surgeon will use X-rays and a special microscope to guide the surgery.
• Using special tools, your surgeon will push away the back muscles around the spine to expose the blocked intervertebral foramen.
• Your surgeon will use small tools to remove the blockage inside the intervertebral foramen. The blockage may be a bone spur or a bulging disc. This will relieve pressure on the nerves.
• In some cases, your surgeon might do another procedure at this time, like a laminectomy. This removes part of the vertebra.
• The team will remove the tools and put your back muscles back in place. Someone will then close the small incision in your skin.

What happens after a foraminotomy?

Talk to your healthcare provider about what to expect after your foraminotomy. Within a couple of hours, you should be able to sit up in bed. You might have a little pain, but you can have pain medicines to ease the pain. You should be able to eat a normal diet.

You’ll need to move the affected area carefully. You will be told if you need to avoid any certain movements for a while. (For example, you might need to avoid bending your neck if your foraminotomy was in this region.) You’ll also likely need a soft neck collar if your surgery was in your neck.

You should be able to go home a day or two after your surgery. Be sure to follow all of your provider’s instructions about medicines, physical activity, and wound care. You may need to avoid certain movements for a while. You may be able to do light work in a few weeks, but you may need to avoid heavier work for a few months. Some people might need physical therapy as they recover.

Your provider can give you a realistic idea of what to expect after your surgery. Remember to keep all follow-up appointments. Most people will see a real improvement in their symptoms. Be sure to tell your provider if you don’t get better, or if you have new or worsening symptoms.

Next steps

Before you agree to the test or the procedure make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you are to have the test or procedure
• Who will do the test or procedure and what that person’s qualifications are
• What would happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how will you get the results
• Who to call after the test or procedure if you have questions or problems
• How much will you have to pay for the test or procedure

Results

A systematic review and meta-analysis of studies on open or minimally invasive surgical (MIS) techniques for posterior cervical foraminotomy showed a pooled clinical success rate of 92.7% for the 509 patients managed with the open technique and 94.9% for the 208 patients who had the MIS technique; the difference was not significant^[rx]. There was moderate heterogeneity observed between the included studies in the meta-analysis. The MIS approach for posterior cervical foraminotomy represents a well-established approach to treating cervical radiculopathy resulting from compression of the nerve root within the neural foramen. The MIS technique was developed as an alternative to the traditional open approach to deal with the most common complaints of postoperative neck pain and spasms as a result of the muscular disruption associated with the open approach. Multiple studies have shown a shorter length of stay, faster recovery times, and decreased blood loss with the MIS technique^[rx–rx].

Kim and Kim performed the only prospective randomized study directly comparing the results of open and MIS posterior cervical foraminotomy^[rx]. Nineteen patients were treated with an open approach and 22, with an MIS approach. At 24 months, clinical success was achieved in 16 (84.2%) of 19 patients in the open cohort and 19 (86.4%) of 22 patients in the MIS cohort; the difference was not significant. Skovrlj et al. recently performed a retrospective review of a prospective cohort of patients treated with MIS foraminotomy with and without microdiscectomy. Of the 70 patients (95 cervical levels), 3 (4.3%) had a complication but none required a secondary operative intervention. Five patients needed an anterior cervical discectomy and arthrodesis (a total of 8 levels were arthrodesed) at a mean of 44.4 months after the index surgery. Of those arthrodeses, 5 (5.3%) were at the index level and 3 (2.1%) were at adjacent levels. Overall, those authors found a low rate of arthrodesis needed at the index level (1.1% per index level per year) and a very low rate of adjacent-level disease requiring surgery (0.9% per adjacent level per year).

A NUMBER OF ALTERNATIVES MAY EXIST, DEPENDING UPON YOUR INDIVIDUAL CIRCUMSTANCES. THESE INCLUDE:

• Pain medications – A number of medications may be useful for pain. These include the standard opioid and non-opioid analgesic agents, membrane stabilizing agents and anticonvulsants, as well as the most recent agent to be released- Pregabalin. Special medical treatments such as Ketamine infusions may be appropriate in some situations.
• Nerve sheath injections – A local anesthetic may be injected through the skin of the neck, under CT scan guidance, around the compressed nerve. This is also known as a ‘foraminal block’. Patients frequently obtain a significant benefit from this procedure, and surgery can sometimes be delayed or even avoided. Unfortunately, the benefit obtained from this procedure is usually only temporary, and it tends to wear off after several days, weeks, or sometimes months. This procedure is also an excellent diagnostic tool, especially when the MRI scan suggests that multiple nerves are compressed and your neurosurgeon would like to know exactly which nerve is causing your symptoms.
• Physical therapies – These include physiotherapy, osteopathy, hydrotherapy and massage.
• Activity modification – Sometimes simply modifying your workplace and recreational activities, to avoid heavy lifting and repetitive neck or arm movements, allows the healing process to occur more quickly.
• Other surgical approaches – These include cervical laminectomy, anterior cervical decompression and fusion (ACDF), and an artificial disc replacement. You should discuss these alternatives, together with their potential risks and benefits, with your neurosurgeon.

Pitfalls & Challenges

• In some patients, fluoroscopic visualization of the lower cervical levels can be challenging. Taping the shoulders down can be helpful, as can coning down the x-ray beam (i.e., using an “off-axis” x-ray beam) if a lateral radiograph does not provide a clear image. We use 10° to 15° of angulation of the beam to allow for visualization of lower cervical levels.
• It is important to make the skin incision directly adjacent to the spinous process to avoid having the incision too lateral when docking the tube. An anteroposterior radiograph can be made with the tube overlying the facet joint to confirm where to place the incision off the midline.
• Identifying the lamina-lateral mass junction is critical as this is the best starting point for the laminotomy.
• Intraoperative bleeding from the epidural vessels should be controlled with bipolar cautery or hemostatic agents, which should be removed prior to wound closure.
• A high-speed so-called matchstick burr should be used to remove the lamina.
• Care should be taken when using the burr to remove the superior articular process. Durotomy and nerve sleeve injury can be difficult to manage through a tube and may require conversion to an open procedure. A diamond burr can also be used instead of a cutting burr as they are less prone to damaging the neural soft tissues.
• Once the epidural space is accessible, the pedicle should be identified.
• Foraminotomy is complete when the nerve root is decompressed from the medial to lateral border of the pedicle.
• If disc fragment(s) need to be removed, the nerve should be gently retracted superiorly with a nerve hook.
• Prior to wound closure, ensure that there is no active bleeding from the cervical paraspinal muscles.
• Fascial closure and the closure of subcutaneous tissue are important.