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Laminotomy

Laminotomy is a surgical procedure that is most often used to relieve pressure in the vertebral canal by removing a small part of the lamina of one or more vertebrae. The laminotomy technique is unique from other decompressive surgical procedures like laminectomy because it leaves many ligaments and muscles attached to the vertebral column intact and it requires removing less bone from the vertebrae. For these reasons, a laminotomy is less invasive than conventional vertebral column surgery techniques. Laminotomies are commonly performed as treatment for lumbar spinal stenosis and herniated disks. This procedure has many benefits such as being less invasive and a faster recovery time. With this type of spine surgery, there are also risks that can occur during or after the procedure like infection, hematomas, and dural tears. MRIs are the best type of radiographic imaging when viewing patients that present with lumbar spinal stenosis. However, CT scans can supplement by pinpointing other degenerative abnormalities. Even typical laminotomies are less invasive than a laminectomy, many surgeons have been leaning towards minimally invasive surgeries as an option. Minimally invasive surgeries are often safer and result in less postoperative complications

Anatomy overview

Vertebra Superior View-en

715 Vertebral Column

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 vertebrae (singular: 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 (singular: lamina) 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. In the center of the vertebral arch is a bony projection called the spinous process. The spinous process is located on the posterior (see Anatomical terms of location) side of the vertebrae and serves as the attachment point for ligaments and muscles which support and stabilize the vertebral column. Lateral bony projections called transverse processes are located on each side of the vertebral arch. Each vertebra has two transverse processes that come into contact with the ribs and serve as attachment points for muscles and ligaments that stabilize the vertebral column. The lamina is a segment of bone that is part of the vertebral arch which 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 laminotomies are defined by the type of instrument used to visualize the surgical procedure and what vertebrae the procedure is performed on. A microscopic (microdecompression) laminotomy uses a surgical microscope which is used externally to the patient in order to magnify the area being operated on. An endoscopic (microendoscopic decompression) laminotomy uses an endoscope to visualize the surgical procedure. An endoscope is a small tube-shaped camera inserted into the patient in order to visualize the surgical procedure internally (source). Laminotomies can be performed on vertebrae at any level of the vertebral column. A cervical laminotomy is performed on cervical vertebrae which are vertebrae closets to the head. A thoracic laminotomy is performed on thoracic vertebrae- midlevel vertebrae. And a lumbar laminotomy is performed on lumbar vertebrae which are the vertebrae closest to the sacrum. Furthermore, a bilateral laminotomy is the removal of a part of bone from each of the lamina of a single vertebra. A unilateral laminotomy is the removal of a part of bone from only one lamina of a vertebra.

Procedure

A laminotomy is a surgical procedure that can be performed for a variety of purposes and requires general or spinal anesthesia. Hospital stays are frequently required following a laminotomy although the duration of the stay depends on the physical condition of the patient and the reason for having a laminotomy. A laminotomy takes about 70-85 minutes depending on the type of procedure used (71 minutes for unilateral laminotomy and 83 minutes for bilateral laminotomy). This is a shorter time period compared to a conventional laminectomy which takes over 100 minutes on average. For this procedure the patient lays supine, or lying on their stomach with their back facing up towards the surgeon. An initial incision is made down the middle of the back exposing the vertebra/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 (spinalis muscle) known as the paraspinous muscles must be separated from the spinous process and vertebral arch. In a unilateral laminotomy, these muscles are only detached from the side on which the laminotomy is being performed. During a bilateral laminotomy, these muscles must be removed on both sides. The ligaments connecting the lamina of upper and lower vertebrae, known as ligamenta flava (link) are often removed or remodeled in this procedure to adjust to 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 the lamina on one or both laminae of the vertebrae. Laminotomies can also 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 (5) This procedure is often used to treat patients with excessive pressure in the vertebral column that must be relieved (5) 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 only need access to one lamina yet can perform a bilateral laminotomy- removal of 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

Lumbar stenosis is formally defined as a decline in diameter length of either the neural foramina, lateral recess, or spinal canal. It is known as a decaying disease due to canal beginning to narrow. This contributes to a great amount of pain and discomfort to patients because there is a narrowing of the canal or tightening and because of this the spinal cord and the surrounding nerves pressed tightly against one another. Many symptoms come along with this such as pain, fatigue, weakness of the muscle and numbness. As a result this disease comes with aging or if younger, the patient has experienced an injury that was traumatic resulting in a spinal injury. When symptoms are present in a person complaining of pain, physical examination alone is not sufficient to diagnose if the patient has Lumbar stenosis. In order to diagnose this, more detailed imaging must be observed by means such as a CT scan or MRI scan. In order to treat this condition, one must go through surgery as a way of means to treat. Patients might want to consider a laminotomy as a reason because they simply want to restore their old previous lifestyle that they were accustomed instead giving up their daily routines. One way is that lumbar stenosis patients have pain walking or when they are standing up, so performing an laminotomy will restore that function back. Another reason is if there is any problems with the nervous system due to it being such an significant factor in someone’s life.

Benefits

The laminotomy procedure has many benefits as to why it is a preferred spinal surgery. This technique of procedure is less invasive than that of other procedures such as laminectomy. Once this procedure is done in patients there is a great improvement in pain and mobility. With this technique, it is usually safer than that of other surgeries that are open or invasive. This surgery usually is shorter than that of other decompression procedures by usually having an average duration of 60 minutes whereas other decompression surgeries can have a duration from 90 to 109 minutes. Laminotomy usually is more cost efficient than that of other surgical decompression surgeries. Smaller skin incisions and scarring as well as less surgical trauma are also a benefit of laminotomy. With this procedure, there is usually a faster recovery time that will have a shorter hospital stay. During the surgery there is also a benefit of minimizing the injury to muscles, ligaments, and bones in the spine. Another benefit of this is that general anesthesia is not required and that postoperative spinal instability is limited.

Risks and potential complications

Since this procedure is a surgery technique there are many complications that can occur either during or after the surgery. Some major complications that can occur are cerebrospinal fluid leaks, dural tears, infection, or epidural hematomas. Death is also a risk, however it can occur one per thousand surgeries. Other complications that can occur during surgery are nerve root damage, which can lead to nerve injury or paraplegia, and a significant amount of blood loss that will lead to blood transfusions.

Radiographic imaging

X-Rays

For radiographic imaging, an x-ray is the least effective way to collect information when observing a patient with lumbar spinal stenosis. A CT scan provides a 360 degree compiled view of the vertebrae that is more precise than an x-ray.

MRI

MRI of the lumbar spine showing spinal stenosis

Since an MRI provides excellent imaging of blood vessels and tissues, it is recognized as the best type of imaging to observe signs associated with lumbar compression. The precise measurement of the diameter of the spinal canal is a particularly important component when determining the severity of the stenosis itself. High strength 3-Tesla MRI machines are being utilized due to the increased vascular imaging capabilities. Better resolution capacity allows for more detailed observations by the healthcare provider. The sharp contrast of the high power MRI outlines details in the vertebra that are critical when examining a patient with lumbar spinal stenosis. MRI scanning post invasive surgery is used to see the quality of the surgery itself, yet the appropriate postoperative time elapsed before conducting an MRI is a debated topic.

CT scans

A CT scan is not the most effective imaging technique when observing lumbar abnormalities, however it can supplement an MRI by detecting certain degenerative processes. When determining whether or not a laminotomy will be beneficial for the patient, a healthcare provider must assess the severity of the possible abnormalities. Out of all the potential reasons to have a laminotomy performed, lumbar spinal stenosis is the chief reason. CT scans are used specifically to pinpoint a buckled lumbar ligamentum flavum as well as facet hypertrophy, which are some of the main pathophysiological change indicative of lumbar spinal stenosis. Even though a CT scan can reveal these pertinent signs of lumbar spinal stenosis, it can sometimes give a cloudy image due to the shadowing of the tissue contrast. When this occurs, an intrathecal myelography contrast is conducted with the CT scan to fix the abnormal contrast. A CT scan can also reveal an increase in the cross sectional area of the L3 vertebrae, which ultimately decreases the cross sectional area of the spinal canal. As an increase in the size of the L3 vertebrae occurs, pressure builds up on the cauda equina, commonly causing pain in the lower back and lower extremities. Cauda equina compression can also be due to stenosis of L4-5 region as well. Even though the CT scan allows for intensive image studying, the fixed nature of the image collection process alone is not enough to reach a definitive diagnosis of lumbar spinal stenosis. The outcome of the CT scan can help compile physiological evidence that the patient has lumbar spinal stenosis, and that the patient may potentially benefit from a laminotomy to improve his or her quality of life.

Other than static imaging processes, a CT scan can also be used for observing changes in spinal canal features before and after a laminotomy. One of the main signs of lumbar spinal stenosis is the thickening of the ligamentum flavum, causing it to expand towards the spinal canal. When observing the cross sectional area of the spinal canal of a human cadaver, it was found that the area had decreased due to ligamentum flavum thickening. The ligamentum flavum did not appear to alter the dynamic alterations in the dimensions of the spinal cord. Even after the intervertebral disc was removed, the ligamentum flavum did not appear to be a factor in the change in the dimensions of the spinal canal. By understanding the magnitude of the role that ligamentum flavum hypertrophy plays in lumbar sacral stenosis, the necessity of an invasive lumbar spinal procedure can be accurately measured.

Alternative minimally invasive procedures

Minimally invasive procedures are a more common alternative due to the decreased risk of damaging significant muscle tissue. The difference between invasive and minimally invasive spinal surgeries is that minimally invasive procedures involves a series of small incisions. Minimally invasive procedures can be performed anywhere along the spine, and have been used to treat various abnormalities. The percutaneous pedicle screw fixation technique allows for a procedure that present minimal risk to the patient. Fluoroscopic image guided navigation through these portals allows for surgeons to perform more efficient procedures. Minimally invasive procedures often yield a much faster recovery time than fully invasive surgeries, making them more appealing to patients. Laminectomies have always been the gold standard when treating lumbar spinal stenosis, but recently, less invasive surgeries have emerged as a safer alternative treatment that helps maintain the postoperative structural integrity of the spine.

Spinal microsurgery

Spinal microsurgery is a minimally invasive unilateral laminotomy used to correct bilateral lumbar spinal compression. Spinal microsurgery is the most common and effective microsurgical decompression treatment for patients that present with moderate to severe spinal stenosis. Spinal microsurgeries are performed with high magnification 3D imaging of the fixated area of the spine, reducing the potential risk of harming the architecture of the spine itself.

Endoscopic spine surgery

Endoscopic spine surgeries can be used to treat thoracic lesions, and have been proven to be a much safer option than a thoracotomy. However, an endoscopic spine surgery can be performed to treat other spinal conditions, such as a herniated lumbar disc. Recovery time from this type of surgical treatment is often very quick, with patients ambulating as little as a few hours of the procedure.

Spinal fusion

Spinal fusion involves fusing two vertebrae together using a spacer, and is intended to prohibit movement at that particular segment. Screws are typically inserted to assure that the spacer is held in place. The most common lumbar spinal fusion occurs between L4 and L5. A lumbar spinal fusion may be recommended when non-surgical treatment options for severe degenerative disc disease are ineffective. A laminotomy would not be effective in this case, since this procedure is concerning a degenerated disc that needs to be removed in order to relive certain symptoms.

Laminotomy vs. laminectomy

Starting with the laminectomy it was the first way physicians have started curing spinal problems. The laminectomy is indeed a very traditional method that involves lessening the amount of pain, numbness, and weakness of muscles. It is a surgery that eliminates the vertebral arch to allow the nerves around it to work properly once again. This method is known for removing all of the bone and the great amount of tissue. It also guaranteed a longer recovery time and is more prone to after surgery complications. There is more likely to have spinal instability while when performing a laminotomy the lamina is only partially removed where as in the laminectomy the lamina is completely ridden of. When going with the option of laminotomy the procedure reduces the amount of back muscle being tempered with and the fact that the laminotomy does not get rid of the spinous process, interspinous, and the ligaments therefore resulting in diminishing muscle weakness, pain the lower back, and instability of the back itself. Since a laminotomy is a newer technique than the standard laminectomy it involves using invasive methods which are more safe than laminectomy and retains more tissue.