A herniated disk, sometimes called prolapsed or slipped disc,  occurs when a disk between two vertebrae ruptures, compressing nearby nerves. Disc herniation can be classified depending on the location as cervical, thoracic, and lumbar. A herniated disc may result from a single excessive strain or injury.

Several risk factors that have the potential to cause disk herniation include excess weight, improper weightlifting, sedentary lifestyle and frequent driving.

Disk herniation or slipping occurs when a fragment of the disc nucleus is pushed out of the annulus (the tough exterior of the disk) and into the spinal canal through a tear or rupture in the annulus.

There are many signs and symptoms associated with a herniated disk that include arm pain or leg pain, burning, tingling and numbness sensations, severe and sudden back pain and neck pain.

A skilled physician can diagnose a herniated disk by reviewing the patient’s medical history, performing physical exams that may include a neurological examination to assess posture, reflexes, muscle strength, walking ability, the ability to feel pinpricks and vibration. Moreover, many imaging tests like X-rays, CT scan, and magnetic resonance (MR) imaging may be suggested to help diagnose a herniated disk.

To treat a herniated disk, the physician may recommend adequate rest, medications such as over-the-counter pain medications, physical therapy, and surgery.

If not carefully treated or managed, a herniated disk may lead to various complications such as chronic back pain or leg pain, loss of control or sensation in the legs, or loss of bowel and bladder function.

Some of the preventive measures that may help prevent disk herniation include regular exercise, maintaining a healthy weight, proper lifting techniques, and using a back brace, mattress, and supportive pillow.

Most people with back and leg pain improve gradually within six weeks when they follow simple interventions; however, it is possible for chronic back pain to continue even after treatment.

The prevalence of symptomatic herniated lumbar disc was found to be between 1 and 3% in Finland and Italy, an article published in the British medical journal (BMJ) - Clinical Evidence reported.

Intervertebral discs are spongy cushions found between the vertebrae of the spine. A herniated disk happens when an intervertebral disk compresses nearby nerves.  The intervertebral disk may move out of place herniate or rupture due to an injury or strain; this can irritate nearby nerves and put pressure on the spinal cord causing pain, numbness or weakness in a part of the body.

Disc herniation can be classified depending on the location into cervical, thoracic, and lumbar disc herniation:

• Cervical herniated disc: A herniated disc in the neck area can press a cervical spinal nerve. Symptomatic cervical herniated discs affect the neck, shoulders, or arms.
• Thoracic herniated disc: Although rare, a herniated disc in the thoracic region affects the mid back.
• Lumbar herniated disc: The vast majority of herniated disks occur at the lower lumbar spine, especially the disk between the last two lumbar vertebrae, and the disk between the last lumbar vertebra and the first sacral vertebra. A herniated lumbar disc affects the lower limbs.

A herniated disc may result from a single excessive strain or injury that leads to the sudden collapse or rupture of a disk. Disk herniation, however, is mostly the result of disk degeneration, which is the gradual, age-related wear and tear that happens to the disk.

Several risk factors can increase the risk of having a herniated disk. These factors include:

• Weight: Being obese can add extra stress on the disks in the lower back, which can raise the possibility of disk herniation.
• Occupation: The risk of back problems including herniated disks increases among people who work in jobs that require repetitive lifting, pushing, pulling, twisting, or bending sideways.
• Genetics: Some investigators believe that some people are more genetically vulnerable to develop a herniated disk than others.
• Gender: Males are more likely to have a herniated disk than females, especially those between the age of 30 and 50.
• Improper weightlifting: Improper lifting technique by activating back muscles instead of leg muscles can lead to a herniated disk.
• Sedentary lifestyle and frequent driving: Sitting or standing in the same position for long hours can increase the risk of having a herniated disk.
• Smoking: Smoking can decrease oxygen supply and speed the degeneration of intervertebral disks.
• Age: An intervertebral disc becomes weaker as age advances, increasing the risk of herniated disks.
• Other risk factors: These may include prolonged exposure to vibration, playing sports, poor muscle tone, and lack of regular exercise.

The spine is made up of 24 individual bones called vertebrae that are stacked on top of each other. The intervertebral discs are flat, round cushioning pads located between the vertebrae and mainly function as shock absorbers.

The major components of an intervertebral disc are an inner gelatinous nucleus pulposus, an outer annulus fibrosus, and cartilage end plates located superiorly and inferiorly. Disk herniation or slipping occurs when a portion of the disc nucleus is pushed out of the annulus into the spinal canal through a tear or rupture.

A herniated disc may press on or pinch a nearby nerve, causing pain, numbness, weakness, tingling in the arms or legs. In addition, the nerve may get irritated and inflamed by the substance that makes up the disc’s jelly-like core, leading to more pain.

Usually, the early stage of disk degeneration has already begun in herniated disks. Further degeneration may be driven by a lessened supply of nutrients, and by a decreased hydrostatic pressure of the nucleus pulposus, making the disk less able to bear loads.

Symptoms of a herniated disc vary greatly depending on the position of the herniated disc and the nerves affected. The most common signs and symptoms of a herniated disk are:

• Arm or leg pain (sciatica) that may shoot when the person coughs, sneezes or moves his/her spine into certain positions.
• Burning, tingling, and numbness that radiate from the buttock into the leg and sometimes into the foot.
• Muscle weakness in certain muscles of one or both legs.
• Severe and sudden back pain and neck pain.
• Loss of reflexes in one or both legs.
• Changes in bladder or bowel function.
• Spasm of the back muscles.

Steps to diagnose herniated disc involve:

Medical history

The physician may ask questions that relate to previous injuries, symptoms, and recent weight loss, fevers, illnesses and problems regarding urination or bowel movements.

Physical examination

Usually, the doctor will examine the spine to check for any tenderness on the back. Moreover, the doctor may use specific physical examination methods such as:

• Neurological examination: A neurological examination helps detect weakness or sensory loss by examining posture, reflexes, muscle strength, walking ability, the ability to feel light touches. Pinpricks and vibration testing may also be used to check the if the patient can feel pain or vibrations, respectively.
• Straight leg raise (SLR) test: This test can accurately reveal disk herniation in patients under the age of 35 by asking the patient to slowly elevate one leg at a time to see if it causes any pain or discomfort in the legs.
• Pressure on a nerve: This test can check if there is compression on a nerve in the neck by asking the patient to bend his or her head forward and to the sides while applying some pressure to the top of the head.

Imaging tests

imaging tests can be used to diagnose a herniated disk. Tests may involve:

• Magnetic resonance imaging (MRI): This imaging technique is the best for viewing the anatomy and soft tissues around the spine. An MRI can accurately reveal the location of the herniated disk and can help detect the affected nerves.
• Computed tomography scan (CT scan): CT scans provide more detailed images of bony structures of the spine than normal X-rays. CT scans can help detect a herniated disc, MRIs are often more accurate.
• Myelogram: This test can reveal if there is compression on the spinal cord or nerves due to herniated discs, bone spurs or tumors. The test is carried out by injecting a contrast material into the surrounding cerebrospinal fluid spaces and taking X-ray images.
• X-rays: X-rays of the spine are taken to reveal other potential causes of pain such as tumors or fractures. Normal X-rays are not helpful in investigating herniated discs because they only detect bone problems, not nerves or spinal cord problems.
• Electromyograms and nerve conduction tests: Electromyograms and nerve conduction tests help measure the speed and strength of the signals traveling through a nerve. During an electromyogram, small metal discs called electrodes are placed on the skin to stimulate the nerves and measure signal speed and strength.

The most common treatment options to treat herniated disk include:

• Rest: The first step to treat severe pain is adequate rest. The patient may be asked to take a few days off from work and to decrease activity for a while.
• Medications: Medications that may help improve symptoms of a herniated disk include:

• Over-the-counter pain medications: In case of mild to moderate pain, over-the-counter pain medications, such as ibuprofen and naproxen, can help relieve it.
• Narcotics: If the pain continues or shows no improvement with over-the-counter medications, a physician may prescribe stronger painkillers called narcotics, such as codeine or an oxycodone-acetaminophen combination.
• Muscle relaxants: These medications are mostly prescribed in cases of muscle spasms. Diazepam is an example of muscle relaxants and is usually taken for a few days if back or leg muscles are very tense.
• Epidural injections: Inflammation and severe pain due to sciatica can be reduced by injecting corticosteroids into the lower back.
• Medication for nerve pain :

1. Antidepressant: Although medications such as amitriptyline and duloxetine are mostly prescribed to treat depression, they also can show positive results in treating nerve pain.
2. Anticonvulsants: Medications such as gabapentin and pregabalin are commonly used to treat epilepsy, but they can also be useful in relieving nerve pain.

• Physical therapy: This form of therapy is recommended to help relieve pain. Physical therapy can help design positions and exercises that minimize pain resulting from a herniated disk. Physical therapy may include massage and manipulation to restore movement and function.
• Surgery: Surgery is recommended for patients who do not respond to non-operative treatments over a period of 6 to 12 weeks. Surgical procedures include:

• Open discectomy: This is performed to remove the portion of the disc that is pressing on a nerve.

• Microdiscectomy: This minimally invasive discectomy is also performed to remove the portion of the disc pinching the nerve. It involves the use of a microscope and microsurgical tools.
• Laminectomy: This surgery is done to remove the portion of the bone that curves around and covers the spinal cord (lamina) and the tissue that is pressing on the nerve or spinal cord.

Complications of herniated disk include:

• Chronic back pain or leg pain.
• Loss of movement or feeling in the legs or feet.
• Loss of bowel and bladder function.
• Very rarely, permanent spinal cord injury.
• A rare condition called cauda equina syndrome may develop due to a herniated disc. This condition is a medical emergency and it involves problems with bowel and bladder function, weakness in one or both legs, and numbness in the buttocks and inner thighs.

Measures to prevent disk herniation may involve:

• Regular exercise: Maintaining an exercise routine can help slow down the age-related deterioration of the intervertebral discs.
• Healthy weight: Maintaining healthy weight is advisable because excess weight increases pressure on the lower back.
• Good posture: Keeping a good posture can be achieved by taking simple precautions such as walking or standing with the head and shoulders bent slightly backward, ensuring the chair is at the correct height for the desk when sitting at a desk, and making sure feet are able to rest flat on the floor.
• Comfortable sitting: Ensuring that the seat is comfortable and supportive when sitting or driving for long periods.
• Proper lifting techniques: When lifting heavy weights, bending at the waist is not advisable, instead, the knees should be bent while keeping the back straight; this activates strong leg muscles to help support the load.
• Using of back brace: Back braces may be recommended in many cases to help support the spine and to prevent injuries in people who lift heavy objects at work. However, excess using of these devices can weaken the muscles that support the spine and can worsen the problem.
• Using of mattress and supportive pillow: Sleeping on a bed with a mattress that matches and supports the spine's natural curves and using supportive pillows can help prevent pain.
• Quitting smoking: Smoking can increase the risk of developing several diseases and disorders and can decrease oxygen supply to the intervertebral disk.

The vast majority of people with herniated discs show improvement with conservative treatment and are able to return to normal functioning within six weeks.

However, it is possible for chronic back pain to continue even after treatment. Some people may need several months to a year or more to return to their normal activities again without having pain in the back. Job-related changes may be required for people who work in jobs that involve heavy lifting or back strain to avoid injuring their back again.

An article published in the British medical journal (BMJ) - Clinical Evidence said that the prevalence of symptomatic herniated lumbar disc is about 1-3% in Finland and Italy depending on sex and age.

Results of a systemic review published in the American Journal of Neuroradiology showed that disk degeneration was in 37% of asymptomatic patients who are 20 years old, while 96% of asymptomatic patients 80 years old had disk degeneration. The prevalence of disk bulge went up from 30% in 20-year-olds to 84% in 80-year-olds. Protrusion of the disk was seen in 29% of those 20 years of age, and in 43% of those 80 years of age.

Despite that the incidence of lumbar disc herniation increases with age, an article published in Clinical Interventions in Aging, showed that the risk decreases with age in the elderly, particularly after the age of 80 years.