Disc Bulge. Slipped Disc. Herniated Disc. What's The Difference?!

Disc Bulge. Slipped Disc. Herniated Disc. What’s The Difference?!

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In this blog piece, we will be discussing the following:

To understand the above terms, we must first have a basic knowledge of the spinal column, its parts and functions:

The Human Spine

There are 33 separate interlocking bones in our spine, each one called vertebra, and collectively called vertebrae. There are 7 vertebrae in the cervical spine, 12 in the thoracic spine, 5 in the lumbar spine, 5 in the sacral region and 4 in the coccygeal region. Only the top 24 vertebrae are moveable, with the remainder being fused. The vertebrae are the building blocks of the spine and make up the spinal column.

The spinal column, its vertebrae and their medical references. Herniated discs most commonly occur between L4 and L5 of the lumbar spine.

In the lumbar region, there are 5 large vertebrae (named L1-5). The main function of the lumbar vertebrae is to bear the weight of the entire trunk whilst providing a moveable support structure and to protect the spinal cord.

Located between each of the vertebrae are the intervertebral discs. A healthy intervertebral disc is made up of two parts. The centre of the disc is called the nucleus pulposus which is made up of a strong gelatinous-like substance. The outer part is called the annulus fibrosus. This is rich in pain carrying nerve fibres called nociceptors, particularly in the outer 1/3 of the disc.

The function of these discs is to act as shock absorbers. When a disc loses its elasticity, it may protrude outside its normal boundary and may compress the spinal nerves or spinal cord. The most common level for a herniated disc to occur is at the level between the fourth and fifth lumbar vertebrae. This is the level where the weight of the entire trunk is being constantly absorbed and where most of the movement in our spine occurs.

As the architectural centre of the body, it also is strongly affected by lower limb biomechanics. This means that any dysfunction or injury of the lower limbs may in time, predispose the spine to possible injury, dysfunction and weakness.

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What’s the difference between a disc bulge, slipped disc and herniated disc?

The terms used to describe disc problems in the lumbar spine are numerous and can be confusing. You’ll hear the terms disc bulge, slipped disc, prolapsed disc etc used frequently and seemingly interchangeably. Generally, they are all used to describe the intervertebral disc protruding from its normal boundary and compressing the spinal nerves or spinal cord.

Technically speaking, a hernia occurs when an organ pushes through an opening in the muscle or tissue that holds it in place. A true herniated disc occurs when the disc annulus cracks or ruptures, allowing the gel-like center to ooze out. Therefore, you’ll also hear a herniated disc referred to as a ruptured disc. Similarly, in medicine the term “prolapsed” is used to describe conditions where internal organs fall down, misalign, or slip out of place, hence the reference to prolapsed disc or slipped disc.

Visual representation of normal, degenerative, bulging, herniated and thinning intervertebral discs.

By comparison, the term disc bulge or disc protrusion refers to the general enlargement of the disc beyond its natural boundary, but the disc annulus remains intact. It may not include any impingement or compression of the spinal nerves or spinal cord.

For the sake of simplicity, I will use the term disc herniation in this article to include all the above.

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What causes herniated discs?

There are numerous causes of disc herniations. Frequently, incorrect lifting technique, or a long history of lifting, bending and twisting in an occupational or recreational capacity can weaken the intervertebral discs.

Personal health factors such as smoking and obesity can also contribute to susceptibility of herniated discs. The ageing process plays an important part. As we get older, the discs lose water content and flexibility; the discs dry out and become more brittle. This heightens the likelihood of the disc annulus cracking.

It is often not one incident but an accumulation of repetitive trauma and weakening over a long period that causes the herniated disc. On questioning, most patients are unable to recall a specific episode that led to the herniated disc.

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What are the signs and symptoms of a herniated disc?

Interestingly, the size of the herniation doesn’t necessarily equate to more pain. A disc bulge in most cases, is discovered by accident; that is, while imaging for an unrelated complaint. These can be quite large and may not cause any signs or symptoms. Other smaller bulges can cause overwhelming pain and be very debilitating.

The symptoms of lumbar herniations vary greatly depending on the location of the protrusion and which spinal nerve root is being compressed. Initially, pain may be experienced in the lower back or buttock region with a sensation of the pain radiating down the back of the thigh and sometimes to the outside of the calf. Sensations may include numbness, tingling, electric shocks, cramping or muscle spasms in the back or foot.

This pain is usually aggravated by bending, twisting, lifting and sitting and often relieved by lying down with the knees bent. This relief is caused by a release of pressure on the disc exerted by gravity.

There may be decreased knee and ankle reflexes and muscular weakness. In more severe cases the foot doesn’t lift properly when walking and is known as ‘foot drop”.

A rare complication is called Cauda Equina Syndrome (CES) and is a surgical emergency. It is caused by a very large herniation that affects many levels and may results in incontinence and other urinary complications. A tell-tale sign is pain or numbness that is known as ‘para-saddle anaesthesia” or pain in the areas that would be touching the saddle if you were sitting in one.

Piriformis Syndrome is a condition that mimics disc pain but is caused by a compression of the sciatic nerve by the piriformis muscle which is located deep in the Gluteal muscle of the posterior hip. Pain, numbness and tingling in the buttocks may be felt along the distribution of the Sciatic nerve.

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How is a herniated disc diagnosed?

A thorough case history is the first step on making an accurate diagnosis. The next step is a comprehensive physical examination that comprises muscle strength, reflex and sensation testing.

An MRI is most commonly used to aid in the diagnosis but is only useful when used in conjunction with the physical examination findings. This is because most patients including those in the mid-twenties that have an MRI may show signs of disc degeneration due to ageing. As discussed earlier, the discs lose elasticity and water content, thus the height between the vertebrae decreases. In the absence of any abnormalities, this is considered a normal part of the ageing process.

MRI image showing normal, bulging and herniated intervertebral discs in the lumbar back region.

An x-ray will not be able to show whether there is prolapse of the disc but can show if there is any narrowing of the disc heights and any other bone abnormalities.

The treatment plan of a patient suffering from a disc herniation depends on numerous factors. The patient’s age, severity of symptoms, the physical examination findings, and the MRI and x-ray results all need to be considered before an effective treatment can be specifically tailored to the patient.

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What are the treatment options for a herniated disc?

Treatment options may be divided into conservative or surgical.

Conservative Treatment Options

  • Self care

Most disc herniations will resolve over time, with 6 weeks being the average recovery time and up to 4 months after the initial onset. It is very important that you allow your body to rest, modify daily activities and avoid any aggravating factors. Initially, bed rest with the knees bent to relieve pressure on the disc may be beneficial but prolonged bed rest for more than 48 hours may be detrimental. Daily activities should be attempted after this period but listen to your body! An attempt to commence training or other exercise at this point may cause further pain and damage and a delay in healing time.

A combination of ice to reduce the inflammation and heat to reduce the muscle spasm or “guarding” can be very effective.

  • Medication

Pharmacological intervention is also useful in the controlling of the pain symptoms. Both NSAIDS (Non-Steroidal Anti-Inflammatory Drugs) and Steroid based medications are useful in the reduction of inflammation around the affected nerves resulting in reduced pain.

Stronger narcotic pain medications may be necessary in more severe cases but should be taken with extreme caution as the side effects may include drowsiness and dependence.

It is extremely important to remember that all medication is only to be used under correct medical advice and is only a short-term solution.

  • Manual Therapy

Your manual therapy practitioner, such as an Osteopath or Physiotherapist, can focus on decreasing the load placed on the disc by addressing muscular imbalances, restoring mobility and strengthening the affected structures. Strong spinal stability is your best defence against preventing reoccurrence and managing disc problems. Correct posture, ergonomic considerations, weight loss and suitable exercise programs all need to be considered. Your manual therapy practitioner can help you and guide you expertly in this area.

Surgical Intervention

As in most cases, surgery should only be considered when all other methods have failed or there is simply no other choice.

The most common procedure is a “discectomy” and basically requires a partial or complete removal of the nucleus pulposus or the central part of the disc. The success rate is reported at being around 85%. The numbness may take longer to go away and depending of the severity of the compression, may never completely resolve.

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The Final Word on Herniated Discs

Pain is an important warning sign and should never be ignored. Whilst we should always endeavour to push ourselves, do so within your own limits. Continually set realistic and attainable goal and do your utmost to reach them. Train hard but also ensure that you have the chance to rest and recover.

Pain and injury to one part of the body over time will affect both surrounding and distal parts. Think of a stone thrown in a pond, the ripples spread far from the site of the initial splash. Think of dysfunction of the spine in the same way!

The best defence we have is to develop and strengthen our spinal stability, avoid repetitive bending and twisting and, if engaged in strength and conditioning training, always lift properly and under expert supervision. The weapons against lower back pain include stretching, exercising regularly, eating well, and drinking adequate water throughout the day.

Getting regular manual therapy treatments such as Osteopathy, Massage and Acupuncture, can help you relieve pain, restore mobility, strengthen spinal structures, and guide you in managing issues with your back in your everyday life.

If you have any further questions about how Osteopathy can help, feel free to book a free 15-minute phone consultation. Alternatively, you can book an appointment online and let us get you back in health!