What is the structure of the spinal disc?

The intervertebral disc can be imagined as a small jelly-like sac lodged between adjacent spinal bones (vertebrae). It has two parts: a soft inner part (nucleus) and a tough fibrous outer layer (annulus). The disc is attached to the vertebrae above and below and hence cannot ‘slip’ out of place. Again, this reinforces the fact that the phrase “slipped disc” is inaccurate and should be avoided. 

Just like the rest of the body, discs are prone to degeneration. With age, the disc dehydrates & the disc height reduces. This brings the spinal bones (vertebrae) closer together. This narrowing of the space between adjacent bones may cause pinching of the nerves exiting between them. This is rare, however, and degeneration of the spine is a normal part of the ageing process and, in most cases, harmless.

The discs in the lower part of the neck (C5-C6 & C6-C7) are the most common sites of disc bulges in the neck as these segments have a high degree of mobility.

The very bottom of the back (L4-L5 and L5-S1) is where about 95% of disc bulges occur in this region.  

What Causes a disc injury?

• Poor physical fitness
• Prolonged sitting
• Obesity
• Lack of regular exercise
• Overuse injury (repeated bending & twisting). More relevant where extremes of physical activity are present eg. in builders etc
• Age related degenerative changes (ageing is normal though & degeneration on an MRI scan is generally not something to be concerned about)

As the disc degenerates it passes through various stages:

1. Disc bulge  – In this initial stage, the disc is bulging but intact so that the core has not penetrated the outer fibres of the disc & into the spinal canal. 

2. Disc Herniation – In this phase, the core of the disc (nucleus) protrudes out through the outer part of the disc. At this stage the disc may impinge on a nerve root and can give rise to neck or back pain that radiates into the arm or leg.

3. Disc extrusion (prolapse) – In this phase, there is complete rupture of the outer part of the disc and part of the core of the disc slips out through this. There is likely to be compression of the nerves that exit the spine and run down the leg or arm. This can cause severe leg or arm symptoms. The muscles supplied by the affected nerve may show weakness.

Patients are often surprised that their low back or neck pain may decrease or vanish completely at this stage as leg or arm pain or numbness becomes the dominant feature. In severe cases there may be foot drop where you cannot lift the foot due to weakness.

Symptoms of a disc injury:

• Dull or sharp pain in neck/low back
• Symptoms aggravated by bending, sneezing or coughing
• Severe spasm of neck/low back muscles
• Cervical radiculopathy – pain, burning, tingling, and numbness in the arm
• Sciatica – pain, burning, tingling, and numbness in the leg
• Weakness in the muscles of the arm/leg that are supplied by the affected nerve

Pain:

It is the characteristic feature of a spinal disc injury. Patients with a lumbar disc prolapse report pain in the low back and buttock. They may also experience numbness and tingling down one leg. The low back pain also increases while bending, lifting, sneezing or coughing.

A patient with a disc prolapse in the neck usually complains of pain in the neck extending up to the shoulder and the arm. This pain is known to increase while looking downward or coughing & sneezing.

Gentle spinal mobilisations, activity modification, ergonomic advice and help to reduce the pain.

Muscle weakness:

Muscle weakness in the legs or arms can indicate a more significant disc herniation. In the lower back, for example, someone might experience difficulty walking on their toes. With neck involvement, weakness of the hand can make it difficult to hold objects. 

How Long Does it take to recover from a “Slipped Disc” 

This is the million dollar question! Some conditions follow predictable timelines but this is not the case with certain conditions. Certainly, a disc herniation, due to the massive variability in disc herniation severity and symptom type, can vary massively from person to person.

As a guideline, I would recommend planning an initial rehabilitation phase of between 6-12 weeks. This will give a good idea of responsiveness to physiotherapy or chiropractic treatment.  From here, future progress can be predicted with greater accuracy.

In the vast majority of cases, improvement in symptoms will be evident at this stage and therefore the necessity for undergoing surgery can be ruled out. 

Only in rare cases of severe disc injuries with compression of the spinal cord (cauda equina syndrome) would patients need to undergo spinal fusion or disc replacement surgery.

How do I Manage My “Slipped Disc”?

It is important to realise that although the symptoms of a disc herniation may come on very suddenly, the underlying changes that predispose to back pain develop over several years. Factors such as lack of motion, poor general health & deconditioned trunk muscles can predispose the spine to more rapid degenerative changes which can eventually give rise to disc herniations.

Luckily, you can take steps to reduce the odds of reoccurence. This is borne out by research demonstrating a massive reduction in low back re-injury rates in those who undergo specific rehabilitation programmes.
After 12 months re-injury rates were 30% in those who had undergone a rehabilitation programme versus 80% in those who had not.

Occasionally, surgery may be required for a disc herniation but this is quite rare. Clinical guidelines suggest that surgery should only take place if there is no improvement in symptoms over a period of months and in cases where there are changes in bowel or bladder habits or progressive neurological deficits.

Criteria that necessitate the performance of immediate surgery include the following:

• Loss of bowel or bladder control eg incontinence or constipation
• Lack of sensation around the bum or genital region
• Instability while walking
  

Is there any Evidence for Chiropractic Manipulation for Treating a Disc Herniation?:

Santilli V, Beghi E, Finucci S. Chiropractic manipulation in the treatment of acute back pain and sciatica with disc protrusion: a randomized double-blind clinical trial of active and simulated spinal manipulations. Spine J. Mar-Apr 2006;6(2):131-137.

In this study, Santilli performed a randomized double-blind controlled trial assessing the short-and long-term effects of spinal manipulation on acute back pain and sciatica with disc protrusion.

Of 102 patients, 53 received manipulations and 49 received simulated manipulations.
Manipulations appeared more effective on the basis of the percentage of pain-free cases:

local pain 28 vs. 6% (in favour of the chiropractic group)

radiating pain 55 vs. 20% (in favour of the chiropractic group)

Patients receiving manipulations had lower mean pain rating scores (VAS).

They concluded that:
‘This study provides Level I therapeutic evidence that spinal manipulation is significantly more effective than sham treatment for the relief of back and leg pain due to acute (less than 10 days) lumbar disc herniation with radiculopathy.’

There were no side effects from the manipulation. 

To find out more, contact Naas Physio & Chiropractor Clinic on:
(045) 874682

or email us at info@physioclinic.ie