Cervical Laminoplasty

Overview

“Laminoplasty” refers to multiple surgical procedures that involve reconstruction of the vertebral lamina subsequent to the spinal canal being opened. Typically, the term “laminoplasty” refers to the creation of hinges that allow lifting of the lamina without its complete removal.

The purpose of cervical laminoplasty was to prevent issues that often arise from laminectomy, such as postoperative segmental instability, kyphosis, perineural adhesions, and delayed neurological deterioration.

History of Laminoplasty

Laminoplasty has evolved significantly since its inception, with various techniques developed to enhance its effectiveness and reduce postoperative complications. Here is an overview of its history and development:

The initial method of laminoplasty was a modification of Kirita’s laminectomy technique. This involved using an air drill to thin and partially remove the laminae along the midline. The edges of the laminae near the pedicles were further thinned until they became flexible enough to be bent and lifted. Swift lifting of multiple laminae was crucial for decompressing several segments of the spinal cord simultaneously. Once lifted, the laminae were excised using scissors.

Following this, the z-plasty technique for laminoplasty was developed. In this method, once the laminae were thinned, z-shaped incisions were made in each lamina. These laminae were then lifted and secured with sutures, reconstructing the widened spinal canal. This technique showed significant neurological improvement post-procedure.

A more radical modification was the en bloc laminectomy, which involved bilateral cutting of the laminae along a line separating the laminar arches and articular processes, completely detaching them from their bony connections. The laminae were reflected to create a flap that floated on the spinal cord without fixation sutures or bone grafting.

The expansive open-door laminoplasty technique was then introduced. This involves drilling bilateral bony gutters along the laminae border adjacent to the medial section of the pedicles. The lamina border is removed on one side, and the laminae are pushed laterally towards the other side, resembling an opening door, thereby enlarging the spinal canal. Sutures are used to support the yellow ligaments and deep muscles around the facets of the hinge side to prevent the laminar door from closing.

Another significant development was a modified laminoplasty technique that splits the spinous processes and laminae along the midline, creating bilateral hinges along the lateral borders of the laminae. These are then lifted to expand the spinal canal.

While many “new methods” of laminoplasty have been described, the fundamental approaches can be categorized into the open-door technique, involving a hinge on one side, and the double-door technique, utilizing hinges on both sides. Various modifications have been implemented to prevent the expanded lamina from closing, including sutures, autologous bone grafts, hydroxyapatite or other ceramic materials, titanium miniplates or spacers, allografts, and hydroxyapatite screws.

Postoperative kyphosis and neck pain are potential complications arising from detachment of posterior cervical muscles during laminoplasty. Initially, some surgeons detached and then reattached the semispinalis cervicis muscle on the C2 spinous process, but later studies recommended preserving this attachment for better outcomes. Preservation of muscle attachment on the C7 spinous process was also found to be significant.

Techniques were developed to preserve muscle attachments on the spinous processes, such as exposing the spinous processes and laminae on one side via subperiosteal dissection, thus maintaining the attachment of the semispinalis muscles on one side. A prospective randomized study showed that preserving muscle attachment significantly decreased axial pain compared to open-door laminoplasty where muscle attachments were completely dissected.

These advancements led to myoarchitectonic spinolaminoplasty, which demonstrated improved neurosurgical cervical spine scores, minimal loss of lordosis post-surgery, and a low incidence of axial neck pain. Further clinical studies are required to validate these findings and address concerns about postoperative instability and reduced range of motion identified in previous posterior decompression procedures.

Laminoplasty has come a long way, with various innovative techniques improving patient outcomes and reducing complications, reflecting the continuous evolution and refinement of this surgical procedure.

Steps of Laminoplasty

Laminoplasty is a surgical procedure designed to relieve pressure on the spinal cord in the cervical spine.

Preparation: Before the surgery, you will undergo a series of pre-operative tests and consultations to ensure you are a good candidate for laminoplasty. On the day of the surgery, you will be given anesthesia to ensure you are comfortable and pain-free during the procedure.

Incision: Once you are anesthetized, the surgeon makes a small incision in the back of your neck. The size and location of the incision depend on the specific area of the spine that needs to be addressed.

Exposure: The muscles and tissues are gently moved aside to expose the cervical vertebrae (the bones of the neck). This allows the surgeon to access the lamina, which are the parts of the vertebrae that form the back of the spinal canal.

Creating the Hinge: The surgeon then creates a hinge on one side of the lamina. This involves carefully cutting through the bone but not completely detaching it. The hinge allows the lamina to open like a door.

Opening the Door: On the opposite side of the lamina, the surgeon makes another cut to create an opening. This side is carefully separated to allow the “door” to swing open, thereby expanding the spinal canal and relieving pressure on the spinal cord.

Securing the Lamina: Once the lamina is opened, it is held in place using small bone grafts or metal hardware such as plates or screws. These supports help to maintain the expanded position of the spinal canal and ensure stability.

Closing the Incision: After securing the lamina, the surgeon will carefully close the incision with sutures or staples. The muscles and tissues are returned to their normal positions, and the skin is closed.

Indication for Laminoplasty

Laminoplasty is a method of decompressing the spinal cord through a dorsal approach that is particularly effective when the lordosis of the cervical spine is maintained.

Laminoplasty is recommended for patients who have cervical spinal canal stenosis, continuous OPLL, and multiple spondylotic lesions, particularly in the lordotic cervical spine. Laminoplasty is indicated for patients with cervical kyphosis who require decompression of more than three levels, as it can improve myelopathy even in the presence of kyphosis.

Clinical improvement after laminoplasty may not be satisfactory if the focal kyphosis angle is more than 13° or if the thickness of OPLL is beyond the K-line. In such cases, the most compressed segment can be subjected to anterior decompression with fusion after laminoplasty.

Postoperative Outcome

Various scales, including the Nurick grade, JOA scale, and Neurosurgical Cervical Spine Scale (NCSS), are used to assess the clinical status of cervical myelopathy. The recovery rate is determined by calculating the difference between the JOA scale score before and after surgery and expressing it as a percentage.

In one study, laminoplasty was found to have good results in improving neurological recovery in patients, with a reported recovery rate of 66%. Neurosurgical literature commonly employs NCSS to describe the status of patients due to its clear and simple nature.

Benefits of Cervical Laminoplasty

The primary benefits of cervical laminoplasty include:

1. Spinal Cord Decompression: Effective relief from symptoms caused by spinal cord compression.
2. Preservation of Spinal Stability: Unlike laminectomy, laminoplasty maintains the integrity of the spinal structure, reducing the risk of postoperative instability.
3. Reduced Risk of Postoperative Deformity: Laminoplasty has a lower risk of post-surgical spinal deformity compared to other procedures.

Risks and Complications

As with any surgery, cervical laminoplasty carries potential risks, including:

• Infection: Postoperative infections can occur but are relatively rare.
• Bleeding: There is a risk of excessive bleeding during or after the surgery.
• Nerve Injury: Potential injury to spinal nerves, which can lead to numbness, weakness, or even paralysis.
• C5 Palsy: A specific complication involving weakness in the shoulder and arm, often temporary but can be permanent in rare cases.
• Recurrent Symptoms: In some cases, symptoms may recur, necessitating further treatment.

Kyphosis Development

Literature has shown that laminoplasty may result in kyphosis development in some patients, although the incidence of this varies between studies. Preserving the functionality of the posterior musculature can prevent the loss of cervical lordosis.

Maintaining the functional preservation of the posterior musculature is crucial because it is responsible for the mechanical force that maintains cervical lordosis, with the semispinalis cervicis and capitis playing a significant role in this. Myoarchitectonic spinolaminoplasty has been observed to lead to the least loss of lordosis, presumably due to the preservation of all posterior muscle attachments.

Biomechanical Studies

According to biomechanical studies conducted on cadavers, the range of motion in response to physiological load increased after laminectomy with or without foraminotomy. However, open-door laminoplasty did not significantly differ from the intact spine in terms of range of movement.

Double-door laminoplasty demonstrated a higher level of stability in the cervical spine compared to laminectomy. However, the load to failure was lower in the spines after laminoplasty. Kyphotic deformity was observed in animal studies after laminectomy in goats and rabbits, while laminoplasty did not result in such deformities.

The results of clinical studies were inconsistent, with some studies demonstrating no significant difference between laminectomy and laminoplasty, while others showed that laminoplasty was associated with better outcomes. The inconsistent results between laminectomy and laminoplasty in clinical studies may be attributed to the failure of laminoplasty procedures to maintain or rebuild muscle attachments.

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