| Back Pain - Disc Pain
A 36 year old man presented with a 12 year history of back pain. He had first felt this pain when he was playing rugby; he picked up an opponent, twisted and turned in a tackle. He felt his back go. The pain increased over the next few days, during which time he could hardly bend at all. The early phase was managed with rest; he commenced an active program of exercise within two weeks, and gradually improved. However, the back remained a significant problem, and then gradually began to deteriorate. The pattern of pain was of regular exacerbations of pain, occurring about 4 times a year and lasting a month, superimposed on chronic but more tolerable back ache.
Exacerbations occurred at times for no apparent reason, and at other times in association with lifting and prolonged sitting. A specific activity such as bending down to lift his daughter or prolonged sitting on the floor could trigger it.
He said that the pain worsened as the day went on, but that he did also have more prominent morning stiffness and pain. Sitting tolerance was about one hour when the back pain was under control. When better, the pain score was about 5/10. He had had to give up competitive sport because of the pain.
The pain was predominantly across the low lumbar region with some milder spread bilaterally and symmetrically into the buttocks and posterior thighs. The pain was not sacral. The pain was more a deep ache but at times there were sharp stabs of pain in the centre of the low back.
Previous treatment included physical therapy, exercise programs, and an interlaminar epidural. Treatment had not helped and he had not gained even short term relief from the epidural. Medication up to tramaldol had been tried with minimal efficacy and he had preferred not to continue with medication.
Systematic questioning did not reveal any red-flag alerts. He said that he felt he was just coping with pain. He said he was not depressed. He was working.
Examination revealed a reasonably good range of movement, with mild ache at end range extension. There were no abnormal peripheral neurological findings. Tenderness was maximal over the L4/5 articular pillars more so than L5/S1 or the sacroiliac joint.
Investigations:
The patient had not had any investigation for 10 years. Plain x-rays and CT scan at that time were unremarkable.
Provisional diagnosis:
Low back pain of unknown origin with some somatic referred pain. The diagnostic protocol of facet joint and disc pain was explained. He was told that there may be an identifiable source of pain in the lower lumbar facet joints or discs. In view of the lack of pain over the sacroiliac joint it was considered that sacroiliac joint pain was unlikely.
Management:
- Explanation:
- The back pain was more than the leg pain, and the leg pain had no characteristics of nerve root pain. Thus, the pain origin was likely to be in a lumbar structure, and not due to nerve injury. Possible pain origins were the lumbar facet joints and the intervertebral discs.
- Imaging including MRI was unlikely to assist with diagnosis, although MRI might point to a diagnosis of disc pain. In particular, a high intensity zone at the posterior part of the disc and grade I or II end plate changes increase the odds of a disc being the primary source of back origin pain.
- Facet joints can theoretically be damaged in the incident he described. The pathology responsible for persisting pain would relate to either articular cartilage changes or to capsular rupture or other associated pathology.
- Discs can also be damaged by such an injury. The likely mechanism leading to chronic pain would be a breach of the end-plate, leading to local nucleus pulposus degradation and the process consistent with internal disc disruption. Pain would develop not only from the end-plate injury, but also from a tear in the innervated part of the anulus fibrosus. Over time increase in pain could occur due to increasing chemical sensitisation of the innervated and torn anulus, from increased anular fibre rupture, and from novel innervation sprouting from the pre-existing innervated anulus.
- The diagnostic algorithm that was adopted here was to first block the lumbar facet joints, and then to proceed to discogram if the facet blocks were negative.
- If he did have lumbar facet joint pain the treatment would be with radiofrequency neurotomy.
- If these blocks of his posterior column were negative, then MRI and possibly discography. Possible treatments for the disc pain included IDET (intradiscal electrothermal therapy), nucleoplasty, disc fusion and disc replacement.
Comments on previous treatment:
- Evidence suggests that early resumption of exercise and normal activity is the best way of managing acute back origin pain. However, not all patients recover using this method. It seems that early activity despite pain helps to prevent chronic pain resulting from deconditioning and perhaps from milder direct injuries, but that it might not help more significant injuries to discs, facet joints and sacroiliac joints.
- The inter-laminar epidural was an inappropriate treatment. It had been given because the practitioner considered that the pain might be from the spinal canal in association with a disc bulge. The pattern of pain here is clearly somatic referred. If an inter-laminar epidural was considered relevant, the practitioner should be able to give a coherent reason why it might work. Perhaps it was felt that there may be some epidural adhesions causing the pain, and that the volume effect of the epidural might help? Note that even for radicular pain, inter-laminar epidurals seem to have the worst evidence in comparison to transforaminal and caudal approaches.
Continuing management:
He underwent bilateral L3/4/5 medial branch block with 0.5 ml of Marcain 0.5% per level. These nerves supply the L4/5 & L5/S1 facet joint. The blocks were negative (see pain chart).
Pain Chart: (score out of 10)
|
LEFT |
RIGHT |
Pre-block |
4 |
4 |
5 minutes |
4 |
4 |
30 minutes |
4 |
4 |
60 minutes |
4 |
4 |
90 minutes |
4 |
4 |
2 hours |
4 |
4 |
3 hours |
4 |
4 |
4 hours |
4 |
4 |
5 hours |
4 |
4 |
6 hours |
4 |
4 |
7 hours |
4 |
4 |
After this an MRI was ordered. This revealed a left contained paracentral disc protrusion at L5/S1 that abutted and mildly displaced the left S1 nerve root. At L4/5 there was a small central contained disc bulge with associated annular tear but no apparent nerve root compromise. Disc height was retained at all levels and there were no obvious end plate changes.
He then underwent discography, subsequent to dissemination of information about the procedure and discussion of the ramifications of the test.
Routine discography, using twilight sedation for the needle insertion stage, was performed at L3/4, L4/5 and L5/S1. He tolerated the procedure well. The results were as follows:
Discogram Results:
|
L3/4 |
L4/5 |
L5/S1 |
Opening pressure |
10 |
5 |
8 |
Maximum pressure |
85 |
80 |
70 |
Volume |
1.2 |
1.6 |
1.7 |
Morphology |
Normal |
Posterior fissure |
Right Posterolateral fissure/ |
Pain production
- at opening + psi |
nil |
Minor -general |
9/10
+ 32 psi |
- retest |
Confirmatory |
Confirmatory |
Confirmatory |
- nature (comparison to patient’s usual pain) |
|
not typical |
Similar -concordant |
- distribution |
|
|
Similar |
 
 
Conclusion:
It was considered that the discogram was positive for primary L5/S1 discogenic pain. The next step was to discuss the possible options for management of this long standing back pain.
In the next edition of Lowbackpain.TV Guide, we will present the management outcomes for this patient.
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