Laminotomy
A laminotomy is an orthopaedic neurosurgical procedure that removes part of the lamina of a vertebral arch in order to relieve pressure in the vertebral canal. A laminotomy is less invasive than conventional vertebral column surgery techniques, such as laminectomy because it leaves more ligaments and muscles attached to the spinous process intact and it requires removing less bone from the vertebra. As a result, laminotomies typically have a faster recovery time and result in fewer postoperative complications. Nevertheless, possible risks can occur during or after the procedure like infection, hematomas, and dural tears. Laminotomies are commonly performed as treatment for lumbar spinal stenosis and herniated disks. MRI and CT scans are often used pre- and post surgery to determine if the procedure was successful.
Anatomy overview
The spinal cord is housed in a bony hollow tube called the vertebral column. The vertebral column is composed of many ring-like bones called vertebra and it spans from the skull to the sacrum. Each vertebra has a hole in the center called the vertebral foramen through which the spinal cord traverses.Laminae are the anatomical structures of primary importance in a laminotomy. Laminae are part of the vertebral arch which is the region of bone on the back side of each vertebra that forms a protective covering for the back side of the spinal cord.
The vertebral arch is composed of several anatomical features in addition to laminae that must be taken into account when performing a laminotomy. In the center of the vertebral arch is a bony projection called the spinous process. The spinous process is located on the posterior or back side of the vertebra and serves as the attachment point for ligaments and muscles which support and stabilize the vertebral column. Each vertebra has two lateral bony projections called the transverse processes which are located on either side of the vertebral arch. Transverse processes come into contact with the ribs and serve as attachment points for muscles and ligaments that stabilize the vertebral column. The lamina is the segment of bone that connects the spinous process to the transverse process. Each vertebra has two lamina, one on each side of the spinous process.
Types
Different types of laminotomy are defined by the type of instrument used to visualize the procedure, what vertebra the procedure is performed on, and whether or not both lamina of a vertebra are operated on or just one.GCommon types of laminotomy:
- Microscopic/Microdecompression laminotomy uses an operating microscope in order to magnify the area being operated on. The operating microscope is typically mounted to the surgery table and held over the area of operation
- Endoscopic/Microendoscopic decompression laminotomy uses an endoscope, a small tube-shaped camera inserted into the patient in order to visualize the procedure internally.
- Cervical laminotomy is performed on cervical vertebrae, the ones closest to the head.
- Thoracic laminotomy is performed on thoracic vertebrae.
- Lumbar laminotomy is performed on lumbar vertebrae, the ones closest to the sacrum.
- Bilateral laminotomy is removal of a part of the bone from both lamina of a single vertebra.
- Unilateral laminotomy is removal of a part of the bone from only one lamina.
Procedure
The procedure of a laminotomy remains largely the same regardless of the instrument used, or the level of vertebrae operated on. Laminotomies require general or spinal anesthesia and frequently require a hospital stay following the procedure—although the duration of the stay depends on the physical condition of the individual and their reason for having a laminotomy. A laminotomy takes about 70–85 minutes depending on the type of procedure used. Unilateral laminotomies typically require less time because bone is removed from only one lamina, whereas bilateral laminotomies usually take more time because bone is removed from both laminae. The level of the vertebrae that the laminotomy is performed on and what instrument is used produce no significant differences in the length of the procedure. Both unilateral and bilateral laminotomies are performed in a shorter time period compared to a conventional laminectomy which takes over 100 minutes on average.During a laminotomy, the individual lies on his or her stomach with the back facing up towards the physician. An initial incision is made down the middle of the back exposing the vertebrae on which the laminotomy will be performed. In this procedure, the spinous process and the ligaments of the vertebral column are kept intact, but the muscles adjacent to the vertebral column known as the paraspinous muscles must be separated from the spinous process and vertebral arch. In a unilateral laminotomy, these muscles are detached only from the side on which the laminotomy is being performed. During a bilateral laminotomy, these muscles must be removed on both sides of the vertebrae. The ligaments connecting the lamina of upper and lower vertebrae, known as Ligamenta flava are often removed or remodeled in this procedure to adjust for the small amount of bone lost. Using either a microscope or an endoscope to have a visual of the procedure, a small surgical drill is used to remove a part of bone from one or both laminae of the vertebrae. Laminotomies can be performed on multiple vertebrae during the same surgery; this is known as a multi-level laminotomy.
A slightly different, but commonly used procedure of laminotomy is the unilateral laminotomy for bilateral spinal decompression. This minimally invasive procedure is often used to treat patients with excessive pressure in the vertebral column that must be relieved. In this procedure, the same spinal ligaments are kept intact and the paraspinous muscles must still be detached. A unilateral laminotomy is performed on one lamina of a vertebra. This removal of bone from one lamina provides an opening into the spinal canal. Using a microscope or an endoscope to visualize the procedure, surgical tools are inserted through this opening into the spinal canal. The surgical tools are then navigated underneath the spinous process and across the spinal canal to reach the other lamina on the opposite side of the vertebra to perform a second laminotomy. The incision for this procedure is smaller because doctors need only access one lamina yet can perform a bilateral laminotomy—remove bone from both lamina of a single vertebra. The unilateral laminotomy with bilateral spinal decompression procedure was developed almost 20 years ago and is a common successful surgical treatment for lumbar spinal stenosis.
Reasons for performing a laminotomy
A laminotomy is typically used to relieve pressure from the spinal canal. Excessive pressure in the spinal canal causes the spinal canal and spinal nerves to be compressed which can be very painful and can impair motor control and/or sensation. A common disorder that causes increased pressure in the spinal canal is lumbar spinal stenosis. Lumbar spinal stenosis is formally defined as a decline in diameter length of either the neural foramina, lateral recess, or spinal canal. Stenosis is classified as a decaying disease because it causes the canal to gradually become more and more narrow which can cause pain or loss of function. Common symptoms of lumbar stenosis are pain, fatigue, weakness of the muscle and numbness. Stenosis can be caused by old age or an injury to the vertebral column and usually requires a CT scan or MRI to diagnose. Performing a laminotomy can relieve pressure in the spinal canal caused by lumbar stenosis and therefore alleviate symptoms.Laminotomies are also performed to create a window into the spinal canal. Laminotomies are frequently used as a way to surgically repair a spinal disc herniation at any level of the vertebral column. A herniated disc can compress spinal nerves and cause intense pain and impaired sensation. Removing a portion of the lamina allows physicians to be able to access and repair the herniated disc. Laminotomies may also be used to treat intraspinal lesions such as spinal tumor or problems with the blood vessels supplying the spinal cord. In any scenario where the inside of the spinal canal must be accessed or there is an increase in pressure in the spinal canal, laminotomy may be used to treat the disorder or alleviate symptoms.