Minimally invasive procedures are those which can be performed through very small skin incisions, usually under local anesthesia, or IV sedation; often on an outpatient basis, thereby avoiding both general anesthesia and hospitalization, and contributing to a speedier recovery and return to normative levels of activity. Often, these are referred to as “band-aid surgeries”, and some are similar to arthroscopy performed by Orthopedic Surgeons, and laparoscopic procedures performed by General Surgeons and Gynecologists.
There are numerous advantages to these procedures, and they are increasingly being adopted by spinal surgeons around the world. However, these procedures should not be treated lightly, nor should the risks be minimized or dismissed; these are truly surgical operations and carry their own subsets of surgical risk. Also, there are definite technical limitations to these procedures, and they are not appropriate for all patients, or all conditions. Some of the commonly performed minimally invasive procedures are summarized below.
Intradiscal Electrothermal Therapy (IDET)
A recently developed minimally invasive procedure, this technique is designed to shrink and tighten the collagen fibers of the annulus fibrosis, the outer layers of the intervertebral disc, which are frequently torn or disrupted in the event of a disc protrusion. The procedure is performed under local anesthesia, with percutaneous insertion of a flexible wire into the intervertebral disc. The wire is then heated to a specific temperature. This is a new procedure, and there are varying reports regarding its safety and effectiveness, as well as the method by which it achieves its results. When effective, it may also work by coagulating some of the nucleus pulposis, the inner, gelatinous substance of the intervertebral disc; or by destroying some of the free nerve endings which have penetrated the outer annular layers of the damaged disc.
The procedure is designed to be performed from only one side (unilateral), but may, on occasion, require bilateral insertion of the wires, for adequate positioning within the confines of the nucleus.
Intradiscal Endoscopic Decompression
Laser-Assisted Internal Disc Decompression; Coblation; Automated Percutaneous Lumbar Disc Decompression
These are minimally invasive procedures which work, in selected cases, by various means, including vaporization (LAIDD), suction-curettage (APLDD), or shrinkage (Coblation) of disc material, and alteration of the proteoglycan substances of the intervertebral disc (which are toxic to nerves when they leak out through tears in the annular fibers). The basic premise for these various procedures is that removing a portion of the disc results in a reduction of intradiscal pressure (reducing pressure within the disc, itself), and can lead to reduction of the disc protrusion, moving the disc away from contact with the nerve roots. These procedures can be performed on an outpatient basis, precluding the need for hospitalization, or general anesthesia.
The LAIDD procedure is performed using fluoroscopy and an integrated laser and flexible endoscope, permitting the surgeon to visualize the internal architecture of the lumbar disc on a video monitor, during the procedure, and to steer the laser fiber to a specific location within the disc space. The other techniques are performed “blind”, using fluoroscopic guidance to direct placement of the instrument within the disc space.
These techniques have proven themselves safe and effective in selected cases, but are generally not useful in cases of extruded fragments, or large ruptured discs, and may not currently be used in the cervical spine (neck).
Endoscopic Disc Excision
The minimally invasive approach to intervertebral disc protrusion is gaining increasing popularity worldwide, because of its safety and effectiveness in a wide range of spinal conditions. As experience has increased, a greater number of conditions have been shown to be amenable to endoscopic approaches, which can be performed on an outpatient basis, and without general anesthesia. The procedure is performed within the confines of a surgical cannula, a metal tube similar in size and shape to a straw. Through this tube is inserted the working endoscope, which contains several channels, permitting insertion of a wide variety of surgical devices, including miniaturized grasping, cutting, and shaving devices, as well as laser fibers, chemicals and irrigation solutions.
Depending upon the technique, and the experience of the surgeon, procedures may be performed not only within the abnormal disc, itself, but also within the spinal canal and neural foramen. Because of the nature of the approach, there is some risk of injury to the nerve root, and this technique may not be advantageous in the treatment of multi-level disc pathology.