The spinal stenosis syndrome is a potential hazard when congenital or developmental narrowing of the bony canal, particularly in its lateral recesses where it can be demonstrated by axial tomography, places the emergent nerve root and its blood supply at risk to further small compressive elements. When lumbar disc degeneration allows rotatory and lateral instability, posterolateral bulging of the annulus fibrosus into the root canal occurs when weight is taken on the ipsilateral lower limb. Symptoms of the spinal stenosis syndrome do not arise until the development of this instability. To relieve the symptoms, the nerve root must be freely mobilised and decompressed by full lateral decompression, with partial or total facetectomy if necessary, by enucleation of the intervertebral disc and by removal of the posterolateral portions of the annuli fibrosi.
1. A review of 204 cases of prolapsed intervertebral disc treated by the author by operation ten to twenty-five years before is presented. Injury was an etiological factor in only 14 per cent. 2. The decision to operate should be made after a clearly defined and controlled, but limited, period of closed treatment. The patients should not have to wait for operation. Treatment by closed methods should not be continued in the absence of detectable signs of improvement. Continuation under such circumstances delays recovery from paralysis, prolongs convalescence and delays return to work. Persistence of paraesthesia and numbness are other probable consequences of such delay. 3. A central disc prolapse is an indication for urgent operation if persistent sphincter disturbance or incomplete bladder evacuation is to be avoided. 4. A recurrence rate of sciatica less frequent than that associated with treatment by closed methods is noted in this and other reported series. True recurrence, as opposed to a prolapse at another level, is rare and is most probably due to continuation of the biochemical process of degeneration leading to further sequestration of disc tissue. On the other hand, the altered spinal mechanics, particularly local rigidity resulting from enucleation of a deranged intervertebral disc, may predispose to prolapse at a higher level or may themselves be the cause of symptoms of "recurrence". 5. Operation gives early and lasting relief of sciatic pain, reduces the need for the subsequent use of a corset and assists the patient to an early return to work. 6. Operation does not affect the decision to change work. This is decided by the length of history before operation and the amount of disc degeneration; and the need to change work is the same whether the patient is treated by closed means or by operation. 7. Apart from simple back raising exercises to strengthen the spinal extensor muscles, no physiotherapy need be given because it is not likely to improve the prognosis. 8. Backache is the most frequent disability after operation (17 per cent) and is related to the degree of degenerative change present before and after operation. Injury precipitated the onset of backache in three cases. Operation does not by itself produce backache. The amount of bone removed has no demonstrable effect on the late results of operation, nor on the subsequent development of degenerative changes. 9. Enucleation of the nucleus is not followed by fibrous ankylosis across the intervertebral space.
