MANAGEMENT OF HERNIATION OF THE LUMBAR DISC F. Postacchini The natural history of lumbar disc herniation

Clinical evolution. It is extremely difficult to study clinically the natural history of a condition causing pain, since patients almost inevitably undergo some form of treatment. This may explain the paucity of information on the natural evolution of the clinical symptoms and signs of disc herniation. In a multicentre prospective study, Weber, Holme and Amlie analysed 208 patients who presented with the clinical features of lumbar radiculopathy probably due to disc herniation. In no case was herniation diagnosed by imaging studies. All the patients were examined between two and four weeks after the onset of symptoms and a questionnaire was used to evaluate their clinical status at three and 12 months. All were instructed to observe complete bed rest for one week. Some were treated with piroxicam, whereas the others were given a placebo. No significant difference in the evolution of signs and symptoms was observed between the two groups. During the first four weeks after the onset of the symptoms, 70% of patients had a considerable decrease in pain and almost 60% had resumed work. By one year, some 30% complained of back pain, decreased working ability and limitation in recreational activities; 19.5% had not resumed work. Four patients had been treated by operation. In a prospective, randomised double-blind study by Fraser, 30 patients had chymopapain chemonucleolysis and 30 were injected with saline. Disc herniation was diagnosed by myelography in all patients. At six weeks, only 37% of patients in the placebo group had a satisfactory clinical result. This increased to 57% at six months but had decreased to 47% by two years. Operation had been undertaken in 40% of patients. The results of this study are not consistent with those reported by Weber et al, but, in the latter trial, the diagnosis of disc herniation had been made solely on clinical grounds by non-specialists. Fraser’s patients had been referred to a specialist centre, probably after failure of conservative management, and the clinical diagnosis of disc herniation had been confirmed by myelography. Pathomorphological evolution. In recent years, numerous studies have shown that a disc herniation may decrease in size or disappear in the course of a few months, no matter whether it is contained, extruded or migrated, or of a small or large size (Fig. 1). In a prospective study, 111 patients with disc herniation or annular bulging diagnosed by CT, had a second CT one year later after one or more epidural injections of steroids. Of the patients with disc herniation, 76% showed a decrease in size, with one-fifth of those demonstrating disappearance of the protrusion, on control CT scans. Only 29% of patients with a bulging annulus fibrosus showed such shrinkage. Deterioration was observed on CT scans in only four patients (5%). Similar findings were observed by Maigne et al; of 48 patients who had a further CT scan one to 48 months after the initial examination, 64% showed a decrease of over 75% in the size of the herniation with shrinkage of between 50% and 75% in 17% of the cases. Large herniations tend to decrease in size to a greater extent, but extruded protrusions of small size show less tendency to spontaneous resolution. A decrease in size may occur in the course of a few weeks before complete resolution of the symptoms. A retrospective study has shown that after a mean period of 262 days, most extruded herniations had become smaller or had disappeared after conservative management, but few of the contained protrusions showed any significant change. Little is known about the mechanisms leading to these changes. In contained protrusions, the main mechanism is likely to be dehydration of the herniated nucleus pulposus. This may account for the higher frequency with which young subjects present a decrease in size of their herniation. In extruded or migrated discs, phagocytosis of herniated tissue by macrophages probably plays the primary role.