A small subset of patients have pain which apparently is generated from lumbar zygapophyseal joints. Typically, these patients complain of local pain and often can point to the involved joint. Movement is painful. Rest is helpful and axial loading particularly produces pain ( Schwarzer et al 1994b ).
Imaging studies demonstrate arthropathy. Joints are hypertrophied. Synovial cysts are common. The cartilage endplates are eroded and both acute and chronic inflammatory changes occur around the articular surfaces. Subluxations are common.
A diagnosis is validated when injection of local anaesthetic into the joint or its innervation produces pain relief. The so-called ‘facet block’ has all of the negatives of any diagnostic block, but if expertly done and interpreted, it does define a group of patients whose pain is partly or largely from arthritic joints. Radiofrequency destruction of the innervation has proven to be useful, providing lasting relief for the majority of patients who fit the diagnostic criteria. In our experience, this is a very small percentage, being no more than 1–2% of patients presenting with back pain ( Schwarzer et al 1994a , 1995c ).
There is still considerable controversy over the reality of the diagnosis. It is odd that pain from arthritic joints should be so easily accepted in every other part of the body and yet denied by some in the spine.
Patients who are identified with apparent pain generators in zygapophyseal joints may be treated by radiofrequency destruction of the innervation of the symptomatic joints. Several papers, indicating that steroid injection in and around the joints are ineffective, have been published. Radiofrequency thermal destruction has been recommended for years, the assumed thermal lesion has been thought to disrupt the nerve anatomy and thus extinguish function. As yet, there are no well-controlled studies of the beneficial effect of denervation, but the personal experience of a number of spinal experts suggests that destruction of the innervation of symptomatic zygapophyseal joints will relieve pain often for long periods of time. There is some question about whether the lesion created is thermal, but the efficacy of the technique in a limited number of patients is recognized by many experts in the field.
The syndrome of spinal stenosis is signified by back pain and leg pain with claudication. Patients typically present first with simple gait disturbance. That is, they have trouble walking well after ambulating for more than a short time. Then pain occurs and the hallmark of the diagnosis is painful weakness in both legs brought on by walking. Typically, these patients are relieved immediately upon cessation of walking and often assume a flexed position to speed resolution of symptoms. These features differentiate it from vascular claudication whose symptoms take longer to resolve after cessation of activity. Sensory complaints are usually stocking-like and suggestive of metabolic peripheral neuropathy with which the problem is often confused. The neurological examination may be entirely normal at rest, but both motor and sensory loss can appear after activity.
The diagnosis is made with imaging studies. Plain X-rays are misleading, but either MR ( Fig. 23.4 ) or CT will make the diagnosis.
The treatment for spinal stenosis when symptoms are severe is surgical decompression. The outcomes are excellent. The issue is when are symptoms serious enough to warrant operation. The majority of patients have mild to moderate incapacity and do not necessarily require surgery. When symptoms become significantly incapacitating or when progressive important neurological deficits occur, then surgery is indicated. Prior to that time, symptomatic treatment is warranted. The symptomatic therapies include modification of lifestyle, adequate analgesia, and an exercise activity programme designed to maximize function and minimize symptoms.
The surgical treatment consists of decompressive laminectomy with foraminotomies and stabilization, if necessary. When severe back pain is an important part of the syndrome, it is probable that fusion will be required. When the syndrome is claudication, then decompression alone will be adequate. It is our experience that over 90% of patients will achieve satisfactory relief of claudication symptoms, while back pain as a complaint is more likely to persist. Even with fusion, it is our experience that no more than 60–70% of these patients achieve satisfactory relief of back pain.