Removal (partial or complete) of the posterior ring (lamina) of the vertebra that forms the spinal canal. The spinal canal holds the spinal cord and nerves. See: Anatomy of the Spine

This procedure is usually performed during a decompressive laminectomy.

The amount of bone removed depends on the extent of the spinal stenosis and is usually determined before the operation by reviewing the patient's MRI or CAT scans of the spine.

In cases of spinal neoplasms a laminectomy is done to decompress the spinal cord, resect underlying epidural tumor, or to allow for opening of the dural membrane to resect intra-dural tumors.

This operation may take one to four hours, according to the number of levels involved and extent of the stenosis. Tumor cases are much more complicated, require meticulous technique, usually under the microscope and may take many hours. Hospital stay is usually more extended and return to physical activities is delayed. Extensive laminectomy may  weaken the ligamentous and muscular support of the spine and in rare cases may necessitate a fusion later on. It is for this reason that a laminectomy is only done if needed and limited to the directly involved levels.

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