What is a Slipped Disc (Disc Herniation)?
The spinal discs lie in between the bones of the spine (vertebrae). There are 23 spinal discs in the spine running from the the top of the neck down to the lower back as far as the pelvis. The purpose of the spinal discs is to act as a shock absorber and to allow a small range of movement between adjacent spinal bones.
The discs are composed of a tough outer ring (annulus fibrosis) and a soft jelly-like core (nucleus pulposus). With most disc herniations (slipped discs), both the inner and outer layers of the disc degenerate to a point that the jelly-like core can escape from its usual location between the spinal bones and compress the nerves as they exit the spine.
This nerve root compression can explain many of the symptoms associated with a slipped disc, such as pain in the thigh & also numbness, tingling or pins and needles in the legs or feet.
Many people will tell you that they had a ‘slipped disc’ and will commonly report how they had somebody ‘put it back into place’. This is not quite correct, as the spinal disc contains a jelly-like material and, therefore, a disc cannot be put back into place.
The healing process for a disc herniation (slipped disc) will take a period of time & the disc cannot be popped in or out. If someone reports their pain going after having their disc popped back in after manipulation then the pain source is unlikely to be from a disc and is more likely a joint related pain.
There is some debate as to whether the symptoms of a slipped disc come about due to direct compression of the disc against the nerve root or whether there is an inflammatory response that takes place in response to a disc herniation that in turn stimulates the surrounding nerves. This inflammation can increase the pressure from the disc bulge on the nerve root. As the inflammatory response is brought under control then the symptoms may subside.
Spinal Disc Injuries (“Slipped Disc”)
Terms frequently used to refer to a disc herniation include:
- Degenerative disc disease
- Prolapsed intervertebral disc
- Pinched nerve
- Slipped Disc
Structure of the disc
The intervertebral disc can be imagined as a small jelly-like sac lodged between adjacent vertebrae. It has two parts: a soft inner part (nucleus pulposus) and a tough fibrous outer layer (annulus fibrosus). The disc is attached to the vertebrae above and below and hence cannot ‘slip’ out of place. Therefore, the use of the phrase “slipped disc” is inaccurate and should be avoided.
Just like the rest of the body, discs are prone to degeneration. When the disc dehydrates as part of the degenerative process, 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.
The discs in the lower cervical spine (C5-C6 & C6-C7) are vulnerable to injury as these segments have a high degree of mobility.
The lower lumbar spine (L4-L5 and L5-S1) are the most commonly injured spinal discs as they have a significant role in weight bearing and are situated at the junction between the stable pelvis and more mobile low back. Indeed, about 95% of disc bulges occur at these two levels.
Causes of disc injuries
- Age related degenerative changes
- Poor physical fitness
- Prolonged sitting
- Lack of regular exercise
- Overuse injury (repeated bending & twisting). More relevant where extremes of physical activity are present eg. in builders etc
- Trauma causing flexion-rotation injury
- Poor posture
As the disc degenerates it passes through various stages:
1. Disc bulge – This is the initial stage wherein the nucleus (core) of the disc presses against the weakened outer fibres. The disc is deformed but intact. At this stage the patient may complain of a dull pain in the low back or neck.
2. Disc protrusion – In this phase, the core of the disc (nucleus) protrudes out through the inner fibres of the outer part of the disc. The outside layers of the disc are still intact but the disc is severely deformed. 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 and is made worse with certain movements, as well as coughing or sneezing.
3. Disc extrusion (prolapse) – In this phase, there is complete rupture of the outer part of the disc (the annulus fibrosus) and part of the core or nucleus 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 the leg or arm becomes the dominant feature.
4. Disc herniation – At this stage the entire nucleus pulposus seeps out of the ruptured annulus fibrosus and lies outside the disc. The surrounding nerves are compressed leading to pain, numbness and tingling in the arm or leg. The muscles supplied by the affected nerve may show weakness. In severe cases there may be foot drop where the patient cannot lift the foot properly.
Usually the disc prolapse occurs to the back & outer edge of the disc. However, if the prolapse occurs more centrally, there may be compression of the spinal cord. This is known as cauda equina syndrome, which is a medical emergency.
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
How Long Does it take to recover from a “Slipped Disc”
People will always pose the questions that clinicians wan’t to avoid: “when will I be better?”. 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 ompression of the spinal cord (cauda equina syndrome) would patients need to undergo spinal fusion or disc replacement surgery.
Pain: It is the characteristic feature of a spinal disc injury. At times the pain may be severe enough to preclude activity. A patient with cervical spine disc prolapse usually complains of pain in the neck extending up to the shoulder and the arm. This pain is known to increase while coughing or sneezing.
Patients with a lumbar disc prolapse report pain in the low back and buttock. The low back pain also increases while bending, lifting, sneezing or coughing.
Gentle spinal mobilisations, activity modification, ergonomic advice and proper lifting techniques help to reduce the pain.
Radiating pain: The herniated disc compresses the nearby spinal nerves causing radiating pain. A person with cervical disc herniation/prolapse will notice pain, numbness and tingling going down one arm (dermatome). Similarly a patient with lumbar disc prolapse/herniation complains of numbness and tingling down one leg.
Radiating pain in the arm/leg due to a pinched nerve can be managed through intermittent cervical or lumbar traction and neural mobilisation techniques.
Muscle spasm and stiffness: The tissues around the disc herniation site will often develop spasm and stiffness. This can often be a driver of part of the symptoms experienced by the patient.
Deep soft tissue massage, muscle energy techniques, joint mobilisation and gentle stretching significantly reduce the spasm and stiffness.
Muscle weakness: In longstanding cases of nerve compression due to cervical disc prolapse, there may be muscle weakness in the arm & hand making it difficult to hold objects. Similarly compression of spinal nerves due to a lumbar disc prolapse may make it difficult for the person to walk or climb stairs.
Selective strengthening of the affected muscles through progressive resisted exercises can help to overcome muscle weakness.
Preventing relapse: Dynamic lumbar stabilisation exercises form the core of the rehab program for a lumbar disc prolapse. Strengthening of the main core muscles – multifidus and transversus abdominis is crucial for preventing recurrence of the condition. Similarly a great emphasis is placed on strengthening of deep stabilizing muscles of the neck while managing a case of cervical disc prolapse.
Cauda equina syndrome: A central disc prolapse in the lumbar (low back) region can cause compression of the spinal cord. In such cases the patient may complain of loss of sensation in both legs, loss of bladder control, and instability while walking.
This needs urgent medical attention.
Back to work after a spinal disc injury
At Naas Physiotherapy clinic, the focus is on developing a personalised treatment plan for each patient. As these injuries take several weeks to heal, compliance to the rehab plan is important. The ‘benefits of movement and an active lifestyle’ and the ‘ill effects of immobility’ in such cases is explained to the patient. Techniques used for treatment include:
- Activity modification guidance/Ergonomic advice for lifting and carrying
- Advice for environmental modification (if needed)
- Joint mobilisation and manipulation
- Manual therapy
- Deep soft tissue massage
- Myofascial release
- Muscle energy technique
- Selective stretching
- Progressive resisted exercises
- Core strengthening – Dynamic lumbar stabilisation
- Complete biomechanical analysis
- Posture and gait analysis
- Correction of muscle strength imbalance
- Balance and proprioceptive exercises
- Post-operative rehabilitation after spinal surgery
Management of a “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 poor posture & deconditioned trunk muscles can predispose the spine to more rapid degenerative changes which can eventually give rise to disc herniations. It would be logical that if the underlying cause of the disc herniation is not addressed then this may predispose to future spine or disc injury. 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.
A disc herniation should be carefully monitored and rehabilitated under professional guidance. Occasionally, surgery may be required for a disc herniation but practice guidelines suggest that this 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.
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