Diagnosis is the cornerstone of clinical medicine. It is the cognitive process of determining the nature and circumstances of a medical condition or, more essentially, the process of identifying the source and cause of a patient’s complaint.

The degree to which the purpose is achieved depends on the strategies employed in the process and the quality of the evidence on which decisions are based in discriminating between conditions that might be contributing to the patient’s complaint. Without a satisfactory diagnosis, patients and their clinicians remain in the dark about the presenting complaints, and management is capricious.

Displacement of disc material is common, and occurs across a spectrum of severity. Least severe is a disc bulge, in which displacement affects more than 50% of the disc circumference, and usually extends less than 3 mm beyond the bony margin.¹⁰ A disc bulge is a normal finding, and its identification on imaging does not allow any inference to be drawn as to the source of pain.

A disc prolapse is any displacement more severe than a disc bulge. Prolapse thus defines a broad category of changes to the disc, which are further sub-classified according to severity and morphology. In disc prolapse, the nucleus pulposus, anulus fibrosus, end-plate cartilage and fragmented vertebral bone may all be displaced. A disc may compress and/or contribute to inflammation of the spinal nerve roots, spinal dura, cauda equina; however, it not invariably prolapses without consequence.  

Prolapse compressing the nerve root is a very common finding, observed in 70% of the asymptomatic population.²⁵ The factors that cause pain in a minority of such prolapses are not well understood, though inflammation is thought to play a key role. Disc prolapse accounts for 5% of low back disorders, and is one of the commonest reasons that patients undergo surgery.¹²

The source of pain is the actual anatomical site from which pain arises. As noted above, the source of pain may not be detectable with any reliability after clinical assessment and imaging tests. ·pain management can be many things.

In some instances it is not necessary to know the precise source of pain. for example, if the treatment is prescription of medication and general exercise, diagnosis other than to rule out a serious condition is not necessary.

On the other hand, if the treatment is to be spinal surgery such as discectomy, or hip replacement, it is important to know the source of pain. In complex pain presentations, interventional diagnostic tests may be required if more specialised and complex target specific treatments are to be applied.·

Cervical radicular pain can be one of the most painful presentations in clinical practice. It is not easy to diagnose it based on pain alone, as there are features in the pain that could implicate somatic and neurological structures. The condition has a good prognosis. Interventions such as epidural injection and surgery should only be contemplated when the pain is uncontrollable despite conservative measures, and/or, neurological loss is progressive and severe.

The cause of pain is the pathological process leading to a particular structure being responsible for this pain. examples of the causes include infection, where pain is caused by chemical irritation of nociceptors and by direct compression of local nerves, fracture and inflammation. ·

Spondylolysis is a unilateral or bilateral stress fracture of the pars inter-articularis, affecting one or more lumbar vertebrae. Repeated flexion, extension, rotation, and torsion, particularly in combination, are thought to be associated with the highest prevalence of spondylolysis.

Lumbar spondylolysis occurs in 6-8% of the general population, and is usually asymptomatic.⁴ The condition is two to three times more common in males than it is in females, and arises most frequently in late childhood or adolescence. ⁵ It is rare for spondylolysis to arise after the age of 20.¹

Spondylolisthesis refers to the anterior slippage of one vertebra on the adjacent caudal vertebra. The majority of spondylolistheses are exclusively attributable to an abnormality of the pars inter-articularis, such as spondylolysis.⁴ 15% of those with spondylolysis progress to spondylolisthesis.⁵ Spondylolisthesis is also produced by pathology such as facet joint incompetence.⁴

Spondylolysis and spondylolisthesis are radiological diagnoses, and both are common in the asymptomatic population. The prevalence of back pain is no higher among adults with spondylolysis and low grade spondylolisthesis,⁴ implying that an observation of either defect does not allow any inference to be drawn as to the source of a patients back pain. The first part of this article addresses spondylolysis, and the second addresses spondylolisthesis.