As we age and our spinal discs begin to dry out, shrink, and become less stable, they can herniate, lose their covering, press on a nerve, and cause all manner of trouble. A herniated disc is an extrusion of a piece of nucleus (the gel-like center) through a tear in the annulus (the tough, leatherlike outer cover). Most disc ruptures occur between ages thirty and forty; the discs still contain a normal amount of gel, but the annulus is beginning to wear out. If the gel remains inside the cover, it is a disc protrusion. If it escapes through a torn annulus, it is a disc extrusion. Extruded pieces of disc may move up or down the spinal canal a quarter to a half-inch or so from the area of herniation. Discs may protrude to the front, the sides, or to the back.
Most disc herniations occur in areas where the spine is maximally bent forward. The forward bending of these segments results in the vertebral bodies coming closer together toward the spinal canal than in the front of the spine. This places more stress on that part of the annulus and disc facing the spinal canal. The lower neck and the lowermost lumbar spine cause the most problems. Lumbar discs are herniated several times more frequently that their cervical counterparts. Presumably, this is because of greater weight on the lumbar spine. Thoracic herniations are rare; those causing problems are even less frequent. Disc herniations may be preceded by a history of intermittent episodes of back or neck pain, possibly with twinges in the leg or arm. This is from the annulus;s being stretched and under tension. After the disc fully herniates, the pain increases and is usually accompanied by pain radiating down the leg or arm, depending on which root or roots are irritated.
If a herniated disc does compress a nerve root, it can cause not only pain but also possible weakness, numbness, and loss of normal reflexes in the area supplied by the root. Cervical or thoracic-herniated discs can compress the spinal cord, and the large lumbar discs can significantly compress the cauda equina. These herniations can result in arm or leg weakness, numbness below the area of the cord or cauda equina compressed by the disc, and bowel and bladder disturbance. Significant compression of the cauda equina usually also causes severe pain in both legs. Depending on the extent of deficit caused by this type of herniation, emergency neurosurgical decompression my be required to minimise the damage to the nervous system and prevent the creation of permanent nerve damage.
Disc herniations are common; 70 percent to 80 percent improve with time and care. Some herniate and heal, then herniate and heal again. Too often, however, people rush to have unnecessary surgery. They then may spend the rest of their lives repairing the repair.
Cervical-disc herniations are less common than lumbar disc herniations even though you move your neck more often than you do your lower back. There is substantially less weight in the neck than in the lumbar area. Nevertheless, because the cervical spine has a smaller internal diameter – canal – and smaller foramen than other parts of the spine, small herniations are more likely to impinge on a spinal root and cause pain to radiate down the arm. Numbing and tingling may occur a far down as the fingertips. The pain is usually most severe when the disc first herniates and compresses the root. A cervical-disc herniation into the canal can also damage the spinal cord.
- Herniation of the C4-5 disc can affect the C5 nerve root. This causes pain in the neck and over to the side of the shoulder and weakness in the other shoulder muscles and in the muscle that bends the elbow. The biceps reflex may be reduced. Sensory changes, such as numbness and tingling, may also occur in the deltoid area, on the side of the shoulder.
- Herniation of the C5-6 disc affects the C6 root. This can cause pain running from the neck down the arm and hand to the thumb and forefinger. Weakness of some shoulder muscles, the biceps, and the wrist muscles that bend the wrists down and to the inside may exist. Sensory changes, along with pain, may extend to the lower arm and the thumb side of the hand. The biceps reflex may be reduced. This is one of the most common results of a cerivcal disc herniation.
- Herniation of C6-7 disc affects the C7 root. Like the previous level, this is also a common site of disc herniation. Pain may radiate down to deep in the forearm and into the middle finger, and sensory changes may occur in the same area. Damage to this root causes weakness in the muscle that bends the wrist down and inward, other muscles that bend the wrist downward, and those that bend the finger, the triceps, and the muscles that raise the wrist inward, and some muscles that straighten the fingers. The triceps reflex may be reduced.
- Herniation of the C7-T1 disc affects the C8 root. Pain may radiate down along the small-finger side of the arm and terminate in the little finger. Sensory changes may occur in the same area. Damage to this root causes weakness in the triceps, the muscles that raise and bend the wrist and fingers, and those that allow you to spread apart and bring together your fingers. The triceps reflex may be reduced.
These are typical but not absolute pain patterns. The same applies to the lumbar roots described below. Some people are wired a little differently.
Arm pain from a herniated cervical disc is common, usually occurring in thirty- to fifty-year-olds. Unlike lumbar discs, which usually herniate from lifting, carrying, or excessive bending, cervical discs are often herniated while we sleep.
Turning the head from side to side or sleeping on the stomach with the head turned to the side is a good position to herniate an already weakened cervical disc. This change in position in bed often occurs as we enter and leave the state of dream sleep. So we may awaken with a crick in our neck, which travels down an arm. Cervical-disc herniations may produce worse pain when a person carries or lifts on the side of the herniation, turns the head to the side, or strains ot bears down through lifting a heavy load, coughing, sneezing, or having a bowel movement.
Bearing down makes all disc herniation pain at any spinal level worse because the pressure within the chest and abdomen increases during this type of effort and is transmitted to the inside of the discs. Any weakness within the annulus allows more disc material to herniate during increased pressure within the disc. In turn, more pressure may be exerted on a compromised spinal root, causing more pain.
Pain from cervical and lumbar herniations is typically reduced when you bend forward, thus opening the spinal canal and the foramina and thereby relieving the pressure on the root. Pain is worse when you bend forward, thus opening the spinal canal and the foramina and thereby relieving the pressure on the root. Pain is worse when you bend backward. In any disc herniation causing root compression, you may experience throbbing pain like a toothache, pins and needles, or burning sensation. The pain may be so severe that your back is locked in spasm, or it may be just a dull ache that increases with movement.
The thoracic spine, behind the chest, is relatively safe from disc herniation because it hardly moves and is curved slightly backward, thus placing more pressure on the front of the discs. When these discs herniate, it is due to the weight on the thoracic spine from the body above the level of herniation or from a trauma, such as falling. A thoracic-disc herniation may cause pain radiating under the ribs, in the chest, upper abdomen, or around the thoracic spine and shoulder blades in the back of the body. Symptoms vary from a band of chest pain , deep, dull pain behind the breastplate or stomach, or pain between the shoulder blades. Disc herniations of this type are not easily recognised by nonspecialists unfamiliar with this problem.
Any lumbar disc can rupture. The ones at the bottom of the spine herniate most frequently because they carry a greater proportion of the body’s weight. Herniated lumbar discs can often be identified by the pattern of pain and nerve loss in the leg. The spinal cord does not extend below L1-2. However, disc herniation in the lumbar spine that primarily affects the foramen – herniating off to the side of the spine – usually damages the exiting root at that level. Those that herniate centrally into the canal may damage the root that exits the spine one level below. This depends on the size of the canal in relation to the disc and the location of the herniation and the roots exiting the dural sac.
At the L3-4 level, a disc herniation may result in damage to the L3 root exiting the spine, on the side of the disc, in the foramen, or the L4 root off to one side in the canal. The same pattern applies to the other lumbar discs. The following patterns of pain, weakness, numbness, and reflex loss exist for various lumbar roots likely to be affected by disc herniations.
- Damage to the L3 root results in pain to the front of the thigh to the inner part of the knee. Sensory changes, such as numbness and tingling, may occur in this area. Weakness may occur in the quadriceps and the muscle that raises the thigh with the knee bent and the foot on the ground. There may be reduction of the knee reflex.
- If the L4 root is damaged, it may result in pain along the nerve root that runs down the leg to the front of the ankle. Sensory changes may occur in the same area. Weakness of the quadriceps and reduction of the knee reflex may exist.
- The L5 root, if damaged, results in pain that radiates down the leg, over the outside of the calf, and over the arch of the foot to the big toe. Muscles controlled by this root raise the foot and curl the big toe upward. Sensory changes may occur in the same area. There is no reflex loss with damage to this root.
- The S1 nerve root can also be damaged, usually from a disc herniation at L5-S1. This causes pain that radiates down the leg into the back of the calf and the outside of the foot. This root, if damaged, causes weakness of the muscle that allows you to stand on your toes. Sensation may be altered in the same area as the pain. The ankle reflex may be reduced.
Sciatica Pain from Lumbar Discs
Sciatica is a term used to describe pain radiating along the route of the sciatic nerve. Sciatica from disc herniations occurs most commonly from a lumbar disc pressing on the L4, L5, and S1 roots, all of which when compressed may radiate pain to the lower leg and foot. The sciatic nerve consists of the L5, S1, and S2 roots.
Generally, leg pain from lumbar-disc herniations is worse when sitting and possibly standing and walking and less when lying in bed on the back with a pillow under the knees or, possibly, on the side.
Diagnosing Nerve Pain From Disc Herniation
An MRI can obtain images from inside the spinal canal and is the most sensitive test for identifying the location of a disc herniation and nerve compression.
If you cannot have an MRI because of metal implant in your body, a CT scan can be done.
Most people with herniated disc recover with rest and pain medications.
Anti-inflammatories, muscle relaxants or NSAIDs to reduce the inflammation around the root.
Epidurals are corticosteroids, combined with local anaesthetics, that are injected into the epidural space. It can help to reduce pain from root compression from disc herniations.
Treating Pain from Cervical-Disc Herniations
Most of the time, the pain from a herniated cervical disc can be controlled with medication and nonsurgical treatment. Wearing a soft cervical support collar for several weeks day and night helps rest your neck. However, wearing too long may weaken your neck muscles. Seek medical advice about long-term use.
Physiotherapy can help open up the cervical foramen where the nerve root exits the spinal canal.
Treating Pain from Lumbar-Disc Herniations
Relief from pain caused by lumbar-disc herniation calls for conservative treatment, such as medications and physiotherapy. You should get out of bed and ambulate as well as you can. Strict bed rest is not beneficial.
Surgery for Disc Herniation
Discectomy, in the neck, antterior decompression are all operations may be used to treat problems from a disc’s pressing a nerve root.
Surgery is sometimes indicated to decompress a root pressed between a disc and a piece of bone or ligament or to remove the portion of the disc that is pressing on the nerve.
Certain types of muscle weakness may lead to early surgery. If your foot is in a dropped position and cannot be raised off the floor, early surgical intervention must be considered.
Surgery does help to eliminate the symptoms of sciatica more quickly than conservative – nonsurgical – treatment.
Key Points about Back Pain from Disc Herniations
- Most disc herniations occur at spinal segments that are maximally bent foward: the lower neck and lumbar spine.
- A lower lumbar-disc herniation may cause true nerve root pain, called sciatica.
- An MRI can obtain images from inside the spinal canal and foramen and is the most sensitive test for identifying the location of a disc herniation and nerve compression.
- Most people with herninated disc recover with rest, pain medications, and, sometimes physiotherapy or epidural injections.
- Progressive or sudden onset of neurological problems or bowel or bladder problems may require surgical intervention.