What is the difference between a disc protrusion/bulge/herniated and a slipped disc?
A disc protrusion is typically classified as a disc with less than 180 degrees of the disc displaced, while a bulging disc is more than 180 degrees.
A healthy intervertebral disc comprises two parts. The centre of the disc is called the nucleus pulposus, which comprises a strong gelatinous like substance. The outer part is the annulus fibrosis. This is rich in pain carrying nerve fibres called nociceptors, in particular the outer 1/3 of the disc. When the disc loses its elasticity, it may protrude outside its normal boundary and may compress the spinal nerves or spinal cord.
A ‘disc bulge’ is a word used to describe findings seen on an MRI study of the spinal discs. The spinal discs are soft cushions that rest between the bones of the spine, the vertebrae. A normal spinal disc is critical to mobility of the spine. The disc functions to absorb energy in the spine, yet also allow the spine to bend and rotate.
A disc bulge is more common in the lower back (Lumbar Spine), but can occur anywhere in the spine, including your neck (cervical). If the disk bugle is progresses and the outer layer of the disc starts to rupture it is referred to as a herniated disc.
Similar to a disc bulge, a disc herniation or protrusion can also extend into a tunnel and compress a nerve. However, unlike a disc bulge, a disc herniation involves tearing of the disc. The fibrous outer ring of the disc tears creating a fissure from the edge of the disc to the nucleus (the jelly-like inner core). This allows the core to protrude, creating an out pouching. This is a Disc Herniation or sometimes called a Disc Protrusion.
Symptoms of a bulging disc include:
- Muscle spasms or cramping
These will depend on the region of the spine where nerve compression occurred, but they typically occur along the spine.
A slipped disc is when a soft cushion of tissue between the bones in your spine pushes out. It’s painful if it presses on nerves. It usually gets better slowly with rest, gentle exercise and painkillers.
A slipped disc (also called a prolapsed or herniated disc) can cause:
- lower back pain
- numbness or tingling in your shoulders, back, arms, hands, legs or feet
- neck pain
- problems bending or straightening your back
- muscle weakness
- pain in the buttocks, hips or legs if the disc is pressing on the sciatic nerve (sciatica)
Not all slipped discs cause symptoms. Many people will never know they have slipped a disc.
In reality, the term disc protrusion or slipped disc is a ‘catch-all’ term for a range of disc problems where a portion of the disc wall becomes weakened and bulges or ultimately disrupts with the soft “Nucleus Pulposus” extending backwards into the spinal canal and irritating or compressing the descending or exiting nerves.
A recent MRI of my spine showed that I have a number of broad based disc protrusions in my lumbar and thoracic spine as well as large disc herniation in my cervical spine but at the moment none are needing surgical intervention.
Source: Spinal Foundation, NHS Spinal Stenosis