The bones (vertebrae) of the spinal column protect nerves that come out of the brain and travel down the back to form the spinal cord. Nerve roots are large nerves that branch out from the spinal cord and leave the spinal column between each vertebra.
The spinal bones are separated by discs. These discs cushion the spinal column and put space between the vertebrae. The discs allow movement between the vertebrae, which lets allows for bending and reaching.
With herniated disc:
- The disc may move out of place (herniate) or break open (rupture) from injury or strain. When this happens, there may be pressure on the spinal nerves. This can lead to pain, numbness, or weakness.
- The lower back (lumbar area) of the spine is the most common area affected by a slipped disc. The neck (cervical) discs are the second most commonly affected area. The upper-to-mid-back (thoracic) discs are rarely involved.
A herniated disc is one cause of radiculopathy. This is any disease that affects the spinal nerve roots.
Sciatica (leg pain):
When a disc slips out to the back, it presses onto the nerves that comes out from the spinal canal. These nerves comes out of the spinal canal to supply the muscles of the legs. Hence by compressing on these nerves, a patient will have severe pain shooting down the leg.
A slipped disc occurs when the circle of connective tissue surrounding the disc breaks down, allowing the soft, inner gel-like part of the disc to bulge out.
The damaged disc can put pressure on the whole spinal cord or on a single nerve root, where a nerve leaves the spinal cord.
This means a slipped disc can cause pain in the area of the protruding disc and also in the area of the body controlled by the nerve that the disc is pressing on.
It’s not always clear what causes a disc to break down, but age is a common factor in many cases.
As a person ages, the spinal discs start to lose their water content, making them less flexible and more likely to split (rupture).
Smoking can also be associated with a slipped disc because it causes the discs to lose their natural flexibility.
Other factors that can put increased pressure and strain on the spine include:
- bending awkwardly
- heavy or awkward lifting
- sitting for long periods, particularly when driving
- being overweight or obese
- weight-bearing sports, such as weightlifting
- severely injuring the back, such as during a fall or car accident
These situations can weaken the disc tissue and sometimes lead to a slipped disc.
Signs & Symptoms
The pain most often occurs on one side of the body.
- With a slipped disc in the lower back, there may be sharp pain in one part of the leg, hip, or buttocks and numbness in other parts. There may also be pain or numbness on the back of the calf or sole of the foot. The same leg may also feel weak.
The pain often starts slowly. It may get worse:
- After standing or sitting
- At night
- When sneezing, coughing, or laughing
- When bending backward or walking more than a few yards
There may also be weakness in certain muscles. Sometimes, it may not be noticeable until a physical examination. In other cases, the patient may have a hard time lifting the leg or arm, standing on the toes on one side, squeezing tightly with one of the hands, or other problems.
The pain, numbness, or weakness often goes away or improves a lot over weeks to months.
The pain may also occur suddenly from incorrect lifting or twisting that aggravates a weak disc. If this is the case, the patient should seek a medical consult immediately.
A careful physical examination and history is almost always the first step. Depending on where the symptoms are, the doctor examines the neck, shoulder, arms, and hands, or lower back, hips, legs, and feet.
The doctor will check:
- For numbness or loss of feeling
- Muscle reflexes, which may be slower or missing
- Muscle strength, which may be weaker
- Posture, or the way the spine curves
The doctor may also get the patient to:
- Sit, stand, and walk. While walking, the doctor may get the patient try walking on the toes and then the heels.
- Bend forward, backward, and sideways
- Move the neck forward, backward, and sideways
- Raise the shoulders, elbow, wrist, and hand and check the strength level during these tasks
Leg pain that occurs when sitting down on an exam table and lifting the leg straight up usually suggests a slipped disc in the lower back.
In another test, bending the head forward and to the sides while slight downward pressure is exerted on the top of the head. Increased pain or numbness during this test is usually a sign of pressure on a nerve in the neck.
Test done may include:
- Electromyography (EMG) to determine the exact nerve root that is involved.
- Myelogram to determine the size and location of disc herniation.
- Nerve conduction velocity test.
- Spine MRI or spine CT will show where the herniated disc is pressing on the spinal canal.
- Spine x-ray to rule out other causes of back or neck pain. However, it is not possible to diagnose a herniated disc by a spine x-ray alone.
MRI of the lumbar spine showing a left paracentral slipped disc at L5/S1 level compressing the left S1 nerve root:
Conservative treatment — mainly avoiding painful positions and following a planned exercise (physiotherapy) and pain-medication regimen — relieves symptoms in most cases of herniated disc.
Medications that can help with the pain:
- Over-the-counter pain medications. If the pain is mild to moderate, over-the-counter pain medication, such as ibuprofen or naproxen may help.
- Narcotics. If the pain doesn’t improve with over-the-counter medications, the doctor may prescribe narcotics, such as codeine or an oxycodone-acetaminophen combination, for a short time.
- Nerve pain medications. Drugs such as gabapentin, pregabalin, duloxetine, tramadol and amitriptyline often help relieve nerve-damage pain.
- Muscle relaxers. Muscle relaxants may also be prescribed if there are muscle spasms.
- Cortisone injections. Inflammation-suppressing corticosteroids may be given by injection directly into the area around the spinal nerves. Spinal imaging can help guide the needle more safely. Occasionally a course of oral steroids may be tried to reduce swelling and inflammation.
The surgeon will make a cut (incision) over the affected area of the spine down to the lamina, the bony arch of your vertebra. An operating microscope is used to enhance visualisation during surgery.
The surgeon will then gently pull the nerve away to expose the prolapsed or bulging disc, and remove just enough to prevent pressure on the nerves.
The potential risks to this surgery include:
- Injury to the nerve root – this can result in weakness and numbness of the lower limb.
- Injury to the dura (covering membrane) of the neural structures resulting in leakage of cerebrospinal fluid. This can result in post-surgery headaches when standing up.
- Infection of the wound.