Bulging vs. Herniated Disc - What's The Difference?

Intervertebral discs - usually referred to as spinal discs - are specialised structures located between the vertebrae (bones) of our back (our spine). These discs act like cushions or shock absorbers, providing flexibility and support, and allowing us to move our spine normally. Each disc is composed of two main parts:

• The annulus fibrosus

  • This is the outer layer of the disc, and it is composed of tough, fibrous cartilage. It surrounds the inner core of the disc and is responsible for maintaining the disc's shape and providing strength.

• The nucleus pulposus

  • This is the inner core of the disc and has more of a firm jelly-like consistency. It contains a high percentage of water and helps provide the disc with its ability to absorb shock. It also helps distribute pressure evenly across the disc during movement.

Our discs play several important roles in our spine:

• Shock absorption. The gel-like substance in the inner core allows the discs to absorb the impact of movements and activities, reducing stress on the spine.

• Flexibility. The discs contribute to our spine's flexibility, allowing us to bend, twist, and perform other movements.

• Spacing. Discs help to maintain a space between our backbones, preventing them from rubbing against each other.

• Support. Discs provide structural support to our spine and help to keep it stable. 

A bulging spinal disc, also known as a disc bulge, occurs when the outer part of the intervertebral disc protrudes outward beyond its normal boundaries. Because of factors such as getting older, wear and tear, or injury, the annulus fibrosus may weaken or develop small tears. When this happens, the inner nucleus pulposus may push against the weakened area, causing the disc to bulge.

What are the symptoms of a bulging disc?

A bulging disc may not cause any symptoms at all. If they do occur, they can vary in intensity and duration and the presence and severity of any symptoms depend on factors such as the location of the bulging disc and whether it is pressing on nearby nerves. Common symptoms of a bulging disc include:

• Pain. This is a common symptom but the location and nature of the pain can vary, depending on the affected disc and the nerves involved. It may be localised to the site of the bulging disc or radiate to other areas of the body leading to symptoms such as sciatica (radiating pain down the leg) in the case of a bulging disc in the lumbar spine. Certain movements, such as bending, twisting, or lifting, may also worsen the pain associated with a bulging disc

• Numbness or tingling. Pressure on nerves near the disc can lead to sensations of numbness or tingling and these may occur in the back, neck, shoulders, arms, or legs, depending on where the bulging disc is. There may also sometimes be weakness in the muscles associated with the affected nerve. 

• Changes in reflex functioning. Pressure on nerves may affect our reflexes, which may become exaggerated or reduced depending on the specific nerves involved.

• Pain reduced on resting. Rest may diminish pain temporarily and people with a bulging disc may find relief when lying down or avoiding certain activities.

A herniated (or ‘slipped’) disc is different from a bulging disc. In a bulging disc, the outer layer of the disc remains intact, and the inner material does not leak out. In contrast, a herniated disc involves a more severe rupture of the outer layer, allowing the inner material to protrude beyond the disc boundary.

What are the symptoms of a herniated disc?

These are the same as those of a bulging disc, with two extra potential sets of symptoms depending on where the herniated disc is:

• Cervical symptoms: If the herniation occurs in the cervical (neck) area of the spine, symptoms may also include neck pain, pain radiating into the shoulders or arms, and potentially headaches.

• Lumbar symptoms: In the case of a lumbar herniated disc (in the lower back) symptoms may include lower back pain, sciatica (pain going down the leg), and weakness or numbness in the affected leg or foot.

It's also important to say that not everyone with a herniated disc experiences symptoms. In some cases, someone may have a herniated disc that is found incidentally on imaging studies (such as an MRI scan) and may have no symptoms.

What causes a bulging or herniated disc?

The causes of bulging or herniated discs are often linked to things that cause wear and tear on them. Common causes include:

Getting older. As we age, our discs lose water content, becoming less flexible and more prone to wear and tear.

Disc degeneration. Degenerative disc disease involves the gradual breakdown of the discs in the spine - as the discs degenerate, they may become more susceptible to bulging or herniation.

Repetitive strain. Repetitive movements, especially those involving the spine, can cause disc wear and tear so any jobs or activities that involve heavy lifting, bending, or twisting may increase the risk.

Posture problems. Maintaining poor posture over an extended period can place excessive stress on the spine, leading to disc issues. Slouching or sitting for prolonged periods without proper support may contribute to disc bulges.

Trauma. Acute trauma or injury, such as a fall, car accident, or sports-related incident, can cause sudden damage to the intervertebral discs including bulging or herniated discs.

Genetics. Genetic factors can play a role in the development of disc problems in some individuals who have a genetic predisposition to conditions that affect the spine.

Obesity. Excess body weight can increase the load on the spine, contributing to disc degeneration and the risk of disc damage.

Smoking. Smoking has been associated with an increased risk of disc degeneration because nicotine and other chemicals in tobacco may affect blood flow to the discs.

Occupation. Jobs that involve prolonged sitting, heavy lifting, or repetitive movements may contribute to the development of disc issues.

Weak core muscles. Weakness in the muscles that support the spine, particularly the core muscles, may increase the risk of disc problems developing.

Diagnosing a bulging or herniated disc typically involves a combination of a medical history, a physical examination, and imaging studies: 

Medical history. Your doctor will take a detailed medical history from you including asking about your symptoms, the duration and intensity of pain, factors that worsen or alleviate the pain, and any previous episodes of back or neck pain.

Physical examination. Examining you allows your doctor to assess your range of motion, muscle strength, reflexes, and any signs of nerve irritation. They may also perform specific tests for nerve compression or irritation.

Imaging studies. These can include an MRI (Magnetic Resonance Imaging) scan, a CT (Computed Tomography) scan, and X-rays. 

Other possible tests include electromyography (EMG) to help identify nerve compression and assess the severity of any nerve damage, a myelogram - which involves injecting a contrast dye into the spinal canal, followed by X-rays or CT scans to help visualise the spinal cord and nerve roots  - and discography (a discogram) that involves injecting a contrast dye into the intervertebral discs to identify specific discs that may be causing pain. This test is more invasive and is normally only used in cases where the diagnosis is unclear.

What are the treatments for bulging or herniated discs? 

Treatment often depends on the severity of symptoms, the location of the disc involved, and other factors such as personal preferences and whether there are any other existing health issues. Common treatment options are:

• Brief periods of rest, followed by a gradual return to normal activities with modifications to avoid exacerbating symptoms.

• Targeted exercises to help strengthen the muscles that support the spine and improve flexibility. Physical therapy may also include techniques to alleviate pain and improve posture.

• Nonsteroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, and other painkillers may be prescribed to manage pain and inflammation. You can purchase some of these from our shop.

• Corticosteroids can be injected into the space around the spinal cord to reduce inflammation and alleviate pain.

• Applying heat or cold to the affected area may help reduce pain and inflammation. Heat can improve blood flow, while cold can numb the area and reduce swelling (never apply ice directly onto the skin).

• Maintaining a healthy weight reduces stress on the spine.

• Strengthening the core muscles to provide better support for the spine.

• Traction to gently stretch the spine to relieve pressure on the discs and nerves. This can be done manually or with specialised equipment.

 Surgical options include microdiscectomy to remove any herniated disc that is pressing on a nerve root, laminectomy to remove part of the lamina (bone) to relieve pressure on the spinal cord or nerves, and - much less commonly - spinal fusion to stabilise the spine and prevent further movement between vertebrae.

If you are experiencing persistent or severe back or neck pain, radiating pain, or neurological symptoms, it is essential to discuss this with your doctor. They can perform a thorough evaluation, order appropriate tests, and recommend a tailored treatment plan based on your specific diagnosis.