SURGERY

Introduction

There are many surgical techniques that attempt to deal with spinal problems by either providing physical support for vertebrae or by removing or modifying vertebral discs and material which are deemed to be damaged or ineffective in some way.

In the great majority of surgical cases I must say that in my experience any relief is temporary. If the spine is stabilised for example by the use of a metal bridge, it soon stiffens up permanently, causing pain in other parts of the spine which the patient had not experienced before, and the metabolism of the supporting vertebrae  also deteriorates over time, no doubt because of the increased stresses placed upon them.

It is also difficult to treat a patient physically if the spine has had parts removed or modified - it is much better to try and work with what nature has provided.

Over 400,000 back operations are performed in the USA every year, yet the great majority of these operations are neither necessary nor effective in treating the underlying causes of mechanical trauma. In fact, patients are generally crippled in the long term through such operations and their quality of life greatly deteriorates over time.

Why are such surgical operations performed if they are known to be inefffective? The answer lies in the fact that a great deal of money (mainly from medical insurance companies) follows the patient to the operating theatre, and it is not in the hospitals' or consultants' interests to turn patients away and to suggest alternative treatment options such as physical therapy. The medical insurance companies and the patients themselves, being ignorant of the possiblities for alternative treatment options, are guided by what consultants recommend. These consultants earn referral commission and are given free access to  hospital facilities and consulting rooms on condition that patients are recommended to the hospital for treatment (viz: surgical operations). If patients are sent elsewhere so that hospital beds lie empty, neither the consultant nor the hospital makes money, which explains why a practice such as ours never receives referrals from hospitals.

The Spinal Fusion Operation

The purpose of  fusing vertebrae together is in theory to stabilise a section of the spine which may need supporting due to slippage or some other deformity and thereby to remove pain.

In practice, the operation is invariably a failure leading to serious and debilitating consequences for the patient.

This is because the cause of the patient's back pain may not be directly due to a splipped disc. If for example the paitient also has a slightly shorter leg ("short leg syndrome") which has led over time to the patient adopting a protective walking gait or posture, then by fixing vertebrae in a rigid position the spine is no longer able to adjust itself to correct any imbalance. Pain becomes more intense than before the operation and often appears in other parts of the body which were not previously affected.

The surgeon concentrates on the vertebrae which needs additional support, but does not take into account the fact that the cause of the imbalance is because the patient has one leg slightly shorter than the other.

The spine is a bio-mechanical wonder and it doesn't pay to mess around with it by cutting away some of the discs or by fusing vertebrae together. If one of the links in the chain is fixed rigid , the whole structure cannot function properly and soon becomes more unstable than before. Hence, untold numbers of patients end up having more than one spinal operation.

When we say "it doesn't pay to mess around"  with the spine, we mean to say from the patient's perspective a surgical spinal operation is a pending disaster: from the hospital's perspective however, the cost of only one night's stay in a private Central London hospital is £900, so a hospital will always gain financially from these operations.

Lumbar Discs

Surgery for removal of a herniated lumbar disc is one of the most commonly performed procedures. An incision is made vertically along the midline of the back, usually about 2 inches long. Some of the muscle overlying the bone which forms the back of the spinal canal, called the lamina, is separated off the bone. A small window is drilled in the laminae overlying the disc herniation. The nerve root is identified and gently retracted away to expose the offending disc herniation. The disc material is then removed and the wound is closed in a way which restores the normal anatomic layers.

Postoperative recovery is relatively short. Patients are up walking the same night or the next morning and discharged home in 3 to 5 days.

The intervertebral discs are cartilaginous plates surrounded by a fibrous ring which lie between the vertebral bodies and serve to cushion them. Through degeneration, wear and tear, or trauma, the fibrous tissue (annulus fibrosus) constraining the soft disc material (nucleus pulposus) may tear. This results in protrusion of the disc or even extrusion of disc material into the spinal canal or neural foramen. This has been called herniated disc, ruptured disc, herniated nucleus pulposus, or prolapsed disc.

This disc herniation may become significant if a nerve root is compressed. Irritation of the nerve root produces pain in the distribution of that nerve, typically down the back of the leg, side of the calf, and possibly into the side of the foot. For this reason, a herniated lumbar disc characteristically produces sciatica but not back pain per se. If sensory function of the impinged nerve root is impaired, numbness will result. The exact area of numbness is determined by the particular root, and may be in the inner ankle, the great toe, the heel, the outer ankle, the outer leg, or a combination of these. Impairment of motor function of the root will cause weakness which again depends on the particular root, and may include weakness of bringing the ankle upward or downward or raising the great toe.

The term lumbar stenosis refers to any narrowing of the spinal canal. The causes are many. The most common is degenerative, occurring in essentially the entire population with age, to varying degrees and with varying clinical significance. This degenerative narrowing is referred to as spondylosis. Another cause of stenosis is the slippage of one vertebra on another, with malalignment and consequent narrowing of the canal; this slippage is called spondylolisthesis. Again, spondylolisthesis can have many causes, most commonly degenerative and traumatic. One of the causes of spondylolisthesis is a defect in a supporting structure of the vertebra called the pars; this defect is known as spondylolysis. As the reader may guess, spondylolysis can have several causes. These include degeneration, trauma, and congenital defects.

Several factors contribute to the narrowing of the spinal canal with degenerative changes. First, wear and tear causes the joints, called facets ("fa-SETS"), to hypertrophy. This may be analogous to degeneration and swelling of other joints in the body. Second, the major ligament of the spinal canal, the ligamentum flavum, undergoes hypertrophy and buckling. Third, the intervertebral discs may bulge posteriorly into the canal or herniate. Fourth, as mentioned above, the vertebrae may slip forward. Finally, these changes may be superimposed on a congenitally narrow canal.

The hallmark of lumbar stenosis is pain in the back and legs which is aggravated by standing and walking and relieved by sitting or forward bending. The syndrome of pain induced by walking is known as neurogenic claudication (from the Latin claudico, to limp). The major condition which this must be distinguished from is vascular claudication, or leg pain on walking caused by insufficient blood flow to the legs. The features which help to distinguish neurogenic from vascular claudication are the folowing:

Pain occurs after varying amounts of exercise, with standing, or with coughing. Vascular claudication is reliably produced with a fixed amount of exercise, such as walking a certain number of blocks, and is rare at rest.

Relief of pain with rest is variable and slow, usually requiring sitting or stooping. Resting in a standing position is usually not sufficient, or may even aggravate the pain. In contrast, the pain of vascular insufficiency is usually immediately relieved by resting in a standing position. This is a key distinguishing feature.

Pain is in a dermatomal distribution (that of a nerve root[s]) rather than the muscles exercised. Sensory loss is also dermatomal, whereas with vascular insufficiency it is in a stocking-glove distribution. Signs of vascular insufficiency should be absent: diminished pulses, foot pallor on elevation, and decreased temperature of the feet.

At surgery, the laminae and ligamentum flavum of the affected levels are removed, effectively unroofing the spinal canal. The neural foraminae are also opened. Alternatively, hemilaminotomies may be performed in cases where the anteroposterior canal diameter is relatively normal. This is a more limited bone removal than laminectomy. The advantages of this procedure over laminectomy have not been conclusively demonstrated.

The issue of stabilization and fusion with laminectomy is controversial. Lumbar instability following decompressive laminectomy for stenosis is rare, occurring at a frequency of about 1%. The majority of patients who develop postoperative instability have some predisposing factor prior to surgery, such as a pre-existing spondylolisthesis. Moreover, lumbar fusions have a high failure rate, and may even promote spondylosis at adjacent levels. Most surgeons presently perform fusions with laminectomy if preoperative X-rays demonstrate instability, and otherwise follow their patients with postoperative X-rays. Stability is maintained if the majority of the facet is left intact and if the disc is not violated. Younger and more active patients may be at more risk to develop instability later.

As in the lumbar and thoracic spine, herniation of the contents of an intervertebral disc may occur when a tear occurs in the annulus fibrosus. However, whereas in the lumbar spinal canal only nerve roots are present, in the cervical canal the spinal cord may be compressed. The symptoms and signs produced are the result of nerve root compression, spinal cord compression, or both.

The most common complaint is neck pain which limits motion and is aggravated by neck extension. Pain also may radiate into one arm, in a pattern characteristic of the particular root involved (see below). Patients often hold the arm elevated and behind the head, presumably because this maneuver reduces the tension on the nerve root and thus lessens the pain. In most cases, the onset of pain is upon awakening, without identifiable trauma or other precipitating event.

Root Compressed C5 C6 C7 C8

Weakness deltoid biceps triceps, wrist extension hand intrinsics, wrist flexion

Sensory Loss lateral shoulder lateral arm & forearm, thumb & lateral aspect of index finger middle finger ring & little fingers

Reflex Involvement deltoid, pectoralis biceps triceps finger flexion

If the disc herniation compresses the spinal cord, certain deficits may result (myelopathy). Weakness in the hands and arms may be more generalized or bilateral, rather than confined to a root distribution. In addition, there may be leg weakness, usually manifested initially by a feeling of heaviness in the legs and noticable difficulty in walking usual distances or up stairs. Examination may show hyperactive reflexes, pathological reflexes, and a spastic gait. Finally, sphincter and sexual function may be compromised, usually later in the progression of myelopathy. Cervical spondylotic myelopathy is discussed in the following section.

Lhermitte's sign refers to a sudden electrical sensation down the neck and back triggered by neck flexion. This was originally described in a patient with multiple sclerosis and dorsal column dysfunction. The conditions which can produce a Lhermitt's sign are:

multiple sclerosis cervical spondylosis cervical disc herniation cervical spinal cord tumor Chiari I malformation radiation myelopathy subacute combined degeneration (caused by vitamin B12 deficiency).

Other signs may help in aiding the physical diagnosis. These are very suggestive of cervical disc herniation when present, but are frequently absent in the presence of the disease (that is, they are specific but not sensitive). Spurling's sign refers to the reproduction or exacerbation of pain upon pushing down on the head and bending it toward the involved side. The reduction of pain when axial traction is applied to the head is also suggestive of a disc. Finally, in the shoulder abduction test raising the affected arm above the head reduces the pain.

Surgical treatment is usually anterior cervical decompression and fusion (ACDF). An incision is made in the neck, usually to the right of the midline. A plane between the muscles of the neck is taken to the cervical spine. The disc material is removed, and the level is usually fused with bone from the patient's hip or banked bone (allograft). Postoperatively, patients may be up walking the same evening or the next morning. Discomfort in swallowing, from retracting the esophagus, occurs commonly and is usually mild and transient. Patients are usually discharged home in 3 to 5 days.

Cervical spondylosis refers to a degenerative process of the cervical spine producing narrowing of the spinal canal and neural foramina, producing compression of the spinal cord and nerve roots, respectively. Through wear and tear with aging, the following processes occur:

Bony ridges (osteophytes) develop on the vertebral bodies adjacent to the areas of motion at the intervertebral discs.

The facets undergo degeneration and hypertrophy, as in the lumbar spine.

The ligamentum flavum undergoes hypertrophy and buckling, again as in the lumbar spine.

The symptoms and the mechanisms which produce them are similar to those associated with herniated cervical discs. However, the two processes are fundamentally different in that disc herniation is an acute event while spondylosis is a chronic, slowly progressive process which may be punctuated by episodes of worsening. The manifestations of radiculopathy were discussed in the previous section. The following discussion focuses on cervical spondylotic myelopathy (CSM).

Myelopathy refers to dysfunction of the long tracts of the spinal cord. It may manifest as weakness and spasticity, sensory loss, position sense loss, and incontinence. Myelopathy develops in only 5-10% of patients with symptomatic spondylosis. Interestingly, coexistent neck and radicular pain are unusual.

Several syndromes of cervical spondylotic myelopathy have been delineated (Gregorius):

Transverse syndrome: corticospinal, spinothalamic, and dorsal column dysfunction.

Motor system syndrome: corticospinal and anterior horn cell dysfunction.

Mixed radicular and long tract syndrome.

Partial Brown-Sequard syndrome.

Central cord syndrome.

The central cord syndrome frequently occurs with minor trauma, especially involving hyperextension. A typical history is a fall, striking the forehead or chin, with hyperextension and immediate weakness of the arms, and to a variable degree of the legs, with variable sensory loss. The presumed mechanism of spinal cord injury is contusion, compression, or ischemia of the cord against a bony spondylotic ridge. In retrospect, there has often been a history of gradual worsening of myelopathic symptoms prior to the fall.

The surgical options are anterior or posterior decompression. Anterior approaches are similar to that described for herniated cervical disc and may be performed at multiple levels as appropriate. Alternatively, the entire vertebral body may be removed (corpectomy) between adjacent levels of spondylosis, or several bodies may be removed. A bony graft is placed for fusion. With long grafts, a plate and screws are usually placed. Posterior decompression involves laminectomy at the affected levels. The effectiveness of posterior decompression is contoversial, but most surgeons today would probably prefer an anterior procedure when feasible.

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