A herniated disc is a condition in which part, or all, of the soft, gelatinous central portion of an intervertebral disc (the nucleus pulposus) is forced through a weakened part of the disc. This results in back pain and leg pain (lumbar herniation) or neck pain and arm pain (cervical herniation) due to nerve root irritation. 

Causes:

The bones of the spinal column, or vertebrae, run down the back connecting the skull to the pelvis. These bones protect nerves as they exit the brain and travel down the back and then to the entire body.
The spinal vertebrae are separated by cartilage discs filled with a gelatinous substance, which provide cushioning to the spinal column. These discs may or rupture from trauma or strain, especially if degenerative changes have occurred in the disc.
Most herniation takes place in the lumbar area of the spine. Lumbar disc herniation occurs 15 times more often than cervical (neck) disc herniation, and it is one of the most common causes of lower back pain. Nerve roots (large nerves that branch out from the spinal cord) may become compressed resulting in neurological symptoms, such as sensory or motor changes. 
Disc herniation occurs more frequently in middle aged and older men, especially those involved in strenuous physical activity. Other risk factors include any congenital conditions that affect the size of the lumbar spinal canal.

Symptoms of Herniated Lumbar discs

• Severe low back pain
• Pain radiating to the buttocks, legs, and feet
• Pain made worse with coughing, straining, or laughing
• Tingling or numbness in legs or feet
• Muscle weakness or atrophy in later stages
• Muscle spasm

Symptoms of Herniated Cervical Discs

• Neck pain, especially in the back and sides
• Deep pain near or over the shoulder blades on the affected side
• Pain radiating to the shoulder, upper arm, forearm, and rarely the hand, fingers or chest
• Pain made worse with coughing, straining, or laughing
• Increased pain when bending the neck or turning head to the side
• Spasm of the neck muscles
• Arm muscle weakness 
  

Normal situation and disc herniation in cervical vertebrae

 Treatment

The majority of herniated discs will heal themselves in about six weeks and do not require surgery. One study found that "After 12 weeks, 73% of patients showed reasonable to major improvement without surgery." 

If pain due to disc herniation, protrusion, bulge, or disc tear is due to chemical radiculitis pain, then prior to surgery it may make sense to try an anti-inflammatory approach. Often this is first attempted with non-steroidal anti-inflammatory medications, but the long-term use of NSAIDS for patients with persistent back pain is complicated by their possible cardiovascular and gastrointestinal toxicity. An alternative often employed is the injection of cortisone into the spine adjacent to the suspected pain generator, a technique known as “epidural steroid injection”. Although this technique began more than a decade ago for pain due to disc herniation, the efficacy of epidural steroid injections is now generally thought to be limited to short term pain relief in selected patients only. In addition, epidural steroid injections, in certain settings, may result in serious complications. Fortunately there are now emerging new methods that directly target TNF. These TNF-targeted methods represent a highly promising new approach for patients with chronic severe spinal pain, such as those with failed back surgery syndrome. Ancillary approaches, such as rehabilitation, physical therapy, antidepressants, and, in particular, graduated exercise programs, may all be useful adjuncts to anti-inflammatory approaches.

Conservative treatment

Pain medications are often prescribed to alleviate the acute pain and allow the patient to begin exercising and stretching.

There are a variety of non-surgical care alternatives to treat the pain, including:

• Bed rest and lumbo-sacral support belt.
• Physical therapy
• Massage therapy
• Non-Steroidal Anti-Inflamatory Drugs (NSAID’s)
• Oral steroids (e.g. prednisone ormethylprednisone)
• Epidural (cortisone) injection
• Intravenous sedation, analgesia-assisted traction therapy (IVSAAT)
• Weight control
• Spinal decompression

Surgery

 Surgery should only be considered as a last resort after all conservative treatments (non-surgical therapy) have been tried, that did not alleviate the pain and heal the disc herniation.

Surgery is indicated if a patient has a significant neurological deficit. The presence of cauda equina syndrom (in which there is incontinence, weakness and genital numbness) is considered a medical emergency requiring immediate attention and possibly surgical decompression.

Surgical options include:

• Microdiscectomy
• Minimally invasive surgery for disc pain
• Laminectomy- to relieve spinal stenosis or nerve compression
• Hemilaminectomy- to relieve spinal stenosis or nerve compression
• Lumbar fusion (lumbar fusion is only indicated for recurrent lumbar disc herniations, not primary herniations)
• Anterior cervical discectomy and fusion (for cervical disc herniation)
• Disc arthroplasty (experimental for cases of cervical disc herniation)
• Dynamic stabilization
• Artificiel disc replacement, a relatively new form of surgery in the U.S. but has been in use in Europe for decades, primarily used to treat low back pain from a degenerated disc.
• Nucleoplasty

Surgical goals include relief of nerve compression, allowing the nerve to recover, as well as the relief of associated back pain and restoration of normal function.