Spontaneous Resorption of Herniated Discs
In the past, when a person has a herniated disc, it would be safe to assume that the condition would be permanent. Fortunately, in recent times, there are many medical studies to refute this assumption. In fact it is now well accepted that about 40-60% of cervical and lumbar disc protrusion will demonstrate regression or reduction in the size of the herniation. However, the mechanism of regression is not well defined.
Outcome for regression is dependent on various factors. It was found that the larger the extrusion or sequestration, the better the rate of resorption / regression. It has been documented by MRI and CT scans that large discal herniations can regress at a great extent in a time period of ranging between 6months to a year. (see image for an example of a MRI scan that shows a disc bulging between the spinal vertebra, L4 and L5)Discs tended to reduce in size early on after onset and more so in the lateral or sequestered type of herniation compared to smaller herniation or those who’s extruded material are found beneath the posterior longitudinal ligament.
Hypothesis for Disc Resorption
The exact mechanism for spontaneous disc resorption is currently unclear. There are various hypotheses. The first hypothesis is the retraction of the disc herniation back into the intervertebral space. If there is bulging or herniation into the annulus fibrosis, retraction can be encountered theoretically, for example, by applying traction onto the spine, which may allow the disc to be “sucked” back in.
The second hypothesis is based on the concept of dehydration. The assumption here is that the disc shrinks with the loss of water content of the herniated disc material.
Recently, there have been more studies asserting that the spontaneous regression is the result of enzymatic degradation. The herniated fragment is treated as a foreign body undergoing inflammatory reaction, with proliferation of blood vessels causing the migration of phagocytes (debris chompers), and finally phagocytosis of the disc material happens. Perhaps, there is a possibility that all three mechanisms take part in the spontaneous regression and the disappearing of the disc material all together.
Is Surgery Warranted Then?
Having discussed that disc re-absorption can and does occur, it is important to emphasize that there are cases that will require surgery. Patients who have a disc prolapse with referred pain (radiculopathy) alone, usually a trial of conservative therapy, example, rest, steroids injection and physiotherapy is warranted. However, patients presenting with progressive weakness (myelopathy) in the muscles, with or without associated radiculopathy are an indication for surgical intervention. This is because neurological deterioration must be avoided as prognosis or full recovery may be adversely affected.