Articles of NNC

SPINE SURGERY TODAY Krishnamurthy Sridhar

In 2004, Surgery on the Spine is not what it was ten or twenty years ago. It is now a modern, technology driven art, which, together with a good clinical judgment on the part of the treating physician , is able to deliver results on par with any other complex surgery in the body.

The spinal column, which is a bony structure, serves essentially two purposes: protection of the Spinal Cord and Transmission of the body weight to the lower limbs. The bony spine envelopes the delicate spinal cord through its entire length, placing the latter in a long bony canal, which runs from the nape of the neck till the natal cleft. This protection is essential as the spinal cord is one of the most delicate of nature’s creations and also one of the most unforgiving. It is easily injured, and once injured or affected, does not give in easily to early recovery. The spinal cord transmits nerves from the brain to the rest of the body. These nerves are given out at intervals, coming out in pairs, on both sides. The bony spinal column also aids in the transmission of the weight of a person’s body to the lower limbs. For this it has to be strong and also stable. The strength of the spine is dependent on the normality of its architecture and a good calcium content of the bone. The stability of the spine is maintained by the same principle as that of a flag pole. The bony spine represents the pole, while the muscles on either side of the spine, in front and behind, represent the ropes that hold the pole in position. None of these work in isolation, in both normal and pathological conditions. The spine however, differs from the flag pole in that it is not a straight rigid structure, but one which is curved, as well as segmented at regular intervals by soft, well hydrated, cushion-like shock absorbers called ‘intervertebral discs’. The segmentation of the spine allows for movements of the body in different directions. This movement is limited to the neck (or cervical spine ) and the back (or lumbar spine). The spine at the chest (or thoracic spine) and the low back (or sacrum and coccyx) is relatively immobile, not allowing for movement. This differential mobility causes the neck and the back to be more affected by the stresses and strains of daily living and therefore leads to an increased risk of malfunction. The differential mobility also has relevance in the event of violent activity or jerks, especially relevant in the setting of an accident. Here the strain is more where the spine is maximally mobile and also at the junction of the mobile and immobile segments.

Modern Spinal Surgery is the result of tremendous technological advances which have vastly improved diagnostic, monitoring and surgical equipment. The advent of CT and MRI scans have revolutionized diagnosis. Two decades ago, physicians had to rely heavily on x-rays and myelograms, which provided but shadows on the x-ray plates, from which they had to use their clinical judgement and deduce the location and the cause of the problem. Technology has given us the boon of computerized images of the body seen on CT and MRI scans. These supply the clinician with all the structural data that he or she may want. The 2D and 3D scans that are available today allow precise localization of the pathology, study of the anatomical details of the problem area and its surroundings and therefore allow for precise planning of the surgical procedure. Dynamic films capture the effect of movement on the spine and spinal cord. These non-invasive techniques are becoming more and more refined to clearly show and differentiate the normal and abnormal. It is also possible with sophisticated software to preoperatively perform a 3D simulaton of the surgery, so that the surgeon could be more prepared and the surgery better planned.

Advanced Monitoring systems in the operating rooms keep the surgeon and the anesthetist informed about the patient’s well being. More advanced monitoring systems allow the anesthetist to aid in the surgery by lowering or raising blood pressure at will, and by actively monitoring and modulating the total circulatory volume and the level of oxygenation of the blood. These precise monitoring systems build confidence in the surgeon, allowing for more complicated surgeries to be performed in patients who have already compromised body systems.

What has perhaps revolutionized spinal surgery today is the availability of the Operating Microscope and related advances and bio-compatible materials that can be safely used to reconstruct the spine. The Operating Microscope is like a lighted telescope. It provides magnification and illumination along with 3D or Stereoscopic vision. This means that an object when looked at under the microscope can be seen upto 20 times larger than it really is. Objects in the depth of the operating field are seen closer than they really are, due to the telescope effect of the microscope. The fibreoptic lighting system of the microscope focuses the light beam to the area of interest. Thus the surgeon is able to see with absolute clarity, and with good lighting the area of interest. The magnification helps in delineating the abnormal from the normal, allowing for precise separation of the former from the latter. While earlier, when operating with the naked eye, very small blood vessels and nerves could not be seen, now with the microscope, these very fine blood vessels and nerves can not only be seen, but can also be saved, thus improving the results of surgery. The use of the operating microscope is established in brain Neurosurgery. This advantage is now being extended to spine surgery—creating the concept of “Spinal Microsurgery”. Spinal surgery has now become a very precise and delicate surgical art, with immense potential to improve the neurological condition of patient and alleviate their problems. This is not restricted to complex spinal disorders but also to simple everyday problems like Lumbar Disc Prolapse. Not so long ago, the surgical procedure for Lumbar disc prolapse entailed removal of the bone behind the spinal nerves (Laminectomy), which was followed by removal of the offending disc material and decompressing the nerves. While the surgery had good results when performed well, there were many instances of continuing problems post-operatively, especially related to the large scar, excessive muscle dissection and retraction, extensive bone removal, retraction of the nerves for visualization of the disc fragments and occasionally complications of surgery. Modern spinal surgery offers ‘Microdiscectomy’ where through a very small skin incision, with minimal muscle dissection, almost no bone removal and very minimal nerve retraction, the surgery is performed successfully. The patient is made to sit up and walk within 24 hours of the surgery, in contrast to the 7 to 10 day confinement to bed following a naked eye surgery. As the patient is more comfortable and is comfortable, the stay in hospital becomes shorter and the patient returns to work faster. Using the microscope the surgeon’s vision is better allowing for surgery without affecting the normal structures to a large extent. Microsurgery has also allowed the surgeon to perform surgeries through routes that are easier for the patient and allow faster recovery. One such example is surgery for Cervical Disc prolapse ( disc prolapse in the neck). Modern surgery (Anterior Cervical Microdiscectomy) is performed from the front of the neck, through a small scar placed in a skin crease (so that it is not visible later). Similarly the surgeon can now perform more efficiently surgeries through smaller openings and with lesser tissue handling.These result in a better outcome, faster recovery, less expense and less number of man hours lost.

Reconstruction of the bony spinal column is a very important component of spine surgery. Unless reconstructed efficiently, the spine will not be able to take the weight of the body. This will result in dislocation or slippage of the spinal segments on each other with a possible disastrous result. The easy availability of bio-compatible materials like medical grade steel, titanium, and many others, along with the development of methods of testing their strength and durability, has revolutionized spinal reconstruction. We are also more aware of the bio-mechanics of the spinal column and the effects of different stresses and strains that are placed on it. These have allowed surgeons to effectively reconstruct the spinal column in a manner that can efficiently bear normal daily activities of the individual. Fractures and dislocations affecting the spinal column have benefited most from this advance. A dislocation, where there is displacement of one vertebral body with respect to the other, can be effectively managed. Following trauma, especially road accidents or falls from heights, the spine can be fractured with dislocations in upto 30 per cent of cases. When this happens, the spinal cord is damaged, partially or wholly. The only way to retrieve any possible function of an injured cord, is to operate and relieve any possible pressure on the spinal cord. At surgery, once the pressure on the spinal cord and nerves is relieved, the spinal column is realigned, new bone is placed between the fractured segments (fusion), and the spine is fixed in position using a metallic implant. The new bone which is placed between the ends of the broken spine induces the growth of fresh bone which eventually leads to the formation of a solid mass of natural bone between the fragments of the broken spine. This takes between three and six months and is the desired end point in treatment of the patient. The function of the implant is to stabilize the unstable, broken spinal column, so that the patient can be mobilized and made to sit up early, and the alignment of the spinal column is maintained so that healing takes places in the correct manner.

Spinal microsurgery is used also to remove tumours and other abnormal tissues from inside the spinal canal and even from inside the spinal cord with relatively minimal side effects. The combined usefulness of MR and CT scans, low risk anesthesia and technology driven microsurgical equipment allow surgeons to perform delicate operations at a depth of even six to eight centimeters through an opening of less than one centimeter. Gone are the days when spinal surgery meant disaster. Today is the day of spinal surgery making the person a better person. More