The spinal column is a stack of bones or vertebrae. A herniated or slipped disc occurs when there is a problem with one of the rubbery cushions between the vertebrae. Each disc has a soft, jellylike nucleus and a strong exterior. If a disc tears and the nucleus leaks out, the spine can shift, causing various symptoms depending on location and severity.
The most common symptom of a slipped disc is pain near the affected area. When the injury occurs, the herniated disc may press on a nerve and cause minor to debilitating pain. If the dislocation is in the lumbar area or the lower back, it can cause electric shock-like pain that affects only one side of the body. Actions such as sitting, or bending at the waist may aggravate the condition and make the pain more intense.
Slipped discs in the lumbar region can press on the sciatic nerve, causing a condition called sciatica. The condition usually manifests as pain that travels from the buttock into the leg and can continue into the foot. Sciatica often accompanies lower back pain, as well. As with other slipped disc-related pain, it usually worsens with movement. Notably, straightening the affected leg is severely painful.
Occasionally, a slipped disc can compress a nerve in the neck, which causes pain in the neck and between the shoulder blades. It is common for the pain to radiate down through the arm to the hands or fingers. Certain neck movements and postures can place more pressure on the nerve, worsening the pain. Depending on the degree of compression, the pain may feel either dull or sharp.
Along with pain, nerve compression can also cause the affected areas to develop paresthesia — tingling, chilling, burning, or numbness. The most common type of paresthesia is a "pins and needles" feeling. Like other symptoms, paresthesia may travel down the path of the compressed nerve. Mild to severe numbness can also manifest.
To move a muscle, the brain generates a signal that it sends through the nerves to a muscle, triggering the motion. When a slipped disc presses on a nerve, it interferes with this process and can reduce strength and cause dysfunction. Sometimes, the weakness is immediately evident. In other cases, it is only noticeable in certain situations or when directly compared to a healthy body part. In some instances, a slipped disc affects dexterity in that region.
Herniated discs can also affect reflexes. Most people are not likely to notice this unless they seek medical examination. A reflex is an involuntary and almost instantaneous motion response to a stimulus. Reflex signals travel along special neural pathways known as reflex arcs that lie in the spinal cord. When a slipped disc presses on a nerve that is part of a reflex arc, it causes slower and diminished reflexes. More severely impaired reflexes may be an indicator for a worse prognosis, even after surgical management.
A rarer symptom of a slipped disc is foot drop, which makes it difficult to lift the front part of the foot. Usually, this is most noticeable when walking; the ball area of the foot will drag along the ground. Some people who have foot drop compensate by lifting their thigh so their foot can clear the floor, leading to a unique motion: steppage gait. Foot drop occurs when a slipped disc presses on one of the nerves responsible for lifting the foot. Usually, this is the peroneal nerve or one of the nerves that supply it, such as the sciatic nerve.
Pressure from a slipped disc on the nerves that travel to the bowels and bladder can lead to incontinence This most often occurs when pressure on the nerve weakens the muscles that hold in urine or fecal matter, causing leakage. Alternatively, compressing a nerve may send signals to the bowels or bladder at the wrong time, causing the muscles to squeeze and release their contents.
A slipped disc can cause cauda equina syndrome (CES). This rare but serious condition occurs when the disc damages the bundle of nerves that sit at the base of the spinal cord, the cauda equina. CES causes extreme back pain, bladder and bowel dysfunction, muscle weakness, sexual dysfunction, and many other symptoms, some of which are permanent even with treatment. These symptoms represent a medical emergency and should be promptly addressed.
A slipped disc can have many effects, but it may also occur without any symptoms. In these cases, a person may not become aware that they have a slipped disc unless they receive medical imaging. Certain physical changes can cause an otherwise asymptomatic herniated disc to begin causing issues, such as weight gain, significant movement, or aging, that either place more pressure on the area or lead to further damage.
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