Sciatica is a symptom of a problem with the sciatic nerve, the largest nerve in the body. It controls muscles in the back of your knee and lower leg and provides feeling to the back of your thigh, part of your lower leg, and the sole of your foot. When you have sciatica, you have pain, weakness, numbness, or tingling. It can start in the lower back and extend down your leg to your calf, foot, or even your toes. It’s usually on only one side of your body. Sciatica refers to pain, weakness, numbness, or tingling in the leg. It is caused by injury to or pressure on the sciatic nerve. Sciatica is a symptom of another medical problem, not a medical condition on its own. Common causes of sciatica include:
- Lumbar Herniated Disc
As a disc degenerates and breaks down, the inner core can leak out through the outer portion of the disc, and this condition is known as a disc herniation or a . A herniated disk refers to a problem with one of the rubbery cushions (disks) between the individual bones (vertebrae) that stack up to make your spine. A herniated disk can irritate nearby nerves and result in pain, numbness or weakness in an arm or leg. General symptoms typically include one or a combination of the following:
- Leg pain (sciatica), which may occur with or without lower back pain. Typically the leg pain is worse than the lower back pain.
- Numbness, weakness and/or tingling in the leg
- Lower back pain and/or pain in the buttock
Most herniated disks occur in your lower back (lumbar spine), although they can also occur in your neck (cervical spine).
Degenerative disc disease in the lumbar spine, or lower back, refers to a syndrome in which a compromised disc causes low back pain. Degenerative disc disease is one of the most common causes of low back pain and neck pain, and also one of the most misunderstood. Simply put, degenerative disc disease describes the symptoms of pain and possibly radiating weakness or numbness stemming from a degenerated disc in the spine. Although there is a slight genetic component to individuals who suffer from DDD, the true cause is probably multifactorial. It could be from simple wear and tear, or may have a traumatic cause. However, it rarely starts from a major trauma such as a car accident.
The spine condition called isthmic spondylolisthesis occurs when one vertebral body slips forward on the one below it because of a small fracture in a piece of bone that connects the two joints on the back side of the spinal segment. Spondylolisthesis refers to the forward displacement, or slippage, of a vertebra from its normal position. Upon diagnosis, the degree of slippage is determined radiographically. Slippage is measured in terms of grades. The cause of are fibrous defects (healed or unhealed stress fractures surrounded by fibrous tissue) in the vertebra which allow forward slippage of the vertebra over time. There also can be a fracture of the pars interarticularis without a vertebral slip. The fracture itself is known as a spondylolysis.
- Lumbar Spinal Stenosis
A common cause of low back and leg pain is lumbar spinal stenosis. As we age, our spines change. These normal wear-and-tear effects of aging can lead to narrowing of the spinal canal. This condition is called spinal stenosis. When the spinal nerves in the lower back are choked, lumbar spinal stenosis occurs and most often leads to leg pain and other symptoms. The typical symptom is increased pain in the legs with walking (pseudoclaudication), which can markedly diminish one’s activity level. Patients with lumbar spinal stenosis are typically comfortable at rest but cannot walk far without developing . Lumbar stenosis symptoms may include:
- Leg pain ()
- Leg pain with walking (claudication)
- Tingling, weakness or numbness that radiates from the lower back into the buttocks and legs.
When a patient presents with the typical symptoms of lumbar spinal stenosis (leg pain, with or without back pain, which is aggravated by walking), a conclusive diagnosis is made using imaging studies from an MRI scan or a CT scan with myelogram.
Arthritis is the most common cause of spinal stenosis. Arthritis refers to degeneration of any joint in the body. In the spine, arthritis can result as the disk degenerates and loses water content.
Piriformis syndrome is an uncommon neuromuscular disorder that is caused when the piriformis muscle compresses the sciatic nerve. The piriformis muscle is a flat, band-like muscle located in the buttocks near the top of the hip joint. This muscle is important in lower body movement because it stabilizes the hip joint and lifts and rotates the thigh away from the body. The piriformis muscle can also irritate the nearby and cause pain, numbness and tingling along the back of the leg and into the foot The exact causes of piriformis syndrome are unknown. Suspected causes include:
- Muscle spasm in the piriformis muscle, either because of irritation in the piriformis muscle itself, or irritation of a nearby structure such as the or hip
- Tightening of the muscle, in response to injury or spasm
- Swelling of the piriformis muscle, due to injury or spasm
- Bleeding in the area of the piriformis muscle.
Diagnosis of piriformis syndrome is made by the patient’s report of symptoms and by physical exam using a variety of movements to elicit pain to the piriformis muscle.
Dysfunction in the sacroiliac joint, or SI joint, is thought to cause low back and/or leg pain. The leg pain can be particularly difficult, and may feel similar to sciatica or pain caused by a lumbar disc herniation. As with most other joints in the body, the SI joints have a cartilage layer covering the bone. The cartilage allows for some movement and acts as a shock absorber between the bones. When this cartilage is damaged or worn away, the bones begin to rub on each other, and degenerative arthritis (osteoarthritis) occurs.