Spinal pain is one of the most common afflictions to affect modern man, with 12-33% of the adult population having low back pain at any given time. Back pain is essentially divided into 2 groups:
- Mechanical back pain
- Inflammatory back pain
Differentiating between the two entities is vitally important since the long term outcome and therefore, the treatment approach are significantly different.
Mechanical back pain is much more frequent and refers to pain that arises from an injury to a specific structure within the spine. The two structures often implicated as the cause of the back pain are the intervertebral discs and facet (zygopophyseal) joints. Although not definitive, pain that is aggravated by flexion of the spine is more likely to reflect discal pathology whereas pain worsened by extension movements is more in keeping with pain from the facets.
However, it is often difficult to be certain regarding the cause of the pain and this is why the entity is referred to as Non-Specific Back Pain. The majority of those with mechanical back pain can expect a full recovery within the first few weeks, with approximately half of the remainder resolving by 12 months.
Irrespective of the cause a major factor that predisposes to mechanical low back pain is weakness of the core stabilizing muscles, including the abdominal and gluteal muscles. As a result a key focus of treatment is the strengthening of these muscle groups. This has been shown to result in up to a 70% reduction in the recurrence of pain. This is particularly important in this population. The other treatments primarily aim to lessen the sufferers’ pain, whilst awaiting the favorable prognosis of the condition to evolve.
It should be noted that the causes of mechanical back pain can lead to compression of adjacent neural tissue, either within the spinal canal or at the intervertebral foramina. This can result in radiating pain in a dermatomal distribution as well as a constellation of neurological symptoms such as paresthesia. Peri-neural injection of corticosteroid is often helpful in this situation with surgery often the last resort.
Inflammatory back pain, on the other hand, is characterized by pain which is exacerbated by rest, relieved by activity, and is often associated with early morning stiffness. The morning stiffness generally lasts for more than 30 minutes. This pattern of back pain is most commonly related to an inflammatory spondyloarthropathy. The classical spondyloarthropathy is the condition termed Ankylosing Spondylitis. As the name implies the spine becomes fused (ankylosed) over time if left untreated, highlighting the importance of early recognition and treatment of the disorder. The mechanisms by which to identify this population at an early as possible stage is a current topic of research, since generally the time to diagnosis is often longer than 7 years.
The treatment approach is based upon anti-inflammatory medication and exercises, the latter of which aiming to maintain flexibility and therefore range of motion. Immunosuppressant therapy, such as Salazopyrin and Methotrexate, has been used for many years with variable response. The recent introduction of therapy that blocks the action of TNF-? (a pro-inflammatory molecule) has demonstrated marked improvements in disease control, and as a result, improvements in symptoms, function, and retardation of disease progression.
Back pain in the paediatric population always warrants further investigation.
Inflammatory spondyloarthropathies do occur in the juvenile population but more commonly the culprit pathology for their pain is spondylolysis. This refers to a defect, either congenital or due to repetitive stress, of the pars interarticularis. A common precipitant is sport, particularly those that transmit a large rotator force through the spine, as occurs in tennis, cricket, and soccer. Treatment involves rest, strengthening of core muscles, and a graduated supervised return to sport.
Finally, spinal pain that is constant, severe, nocturnal, and with no obvious cause necessitates further investigations to exclude a malignant or infective cause.