The Sciatic Nerve is the largest nerve in the body. It begins in the lower back, travels through the buttock and the back of the thigh, divides into two nerves at the knee and ends at your toes. The term “sciatica” refers to a set of symptoms including pain in the low back, buttock, and legs, which can radiate below the knee to the feet and toes. This radiating pain can be experienced in one or both legs along with numbness, tingling and muscle weakness in the hips, knees and ankles. It is important to understand that the term “sciatica” does not describe the specific causes of the radiating pain, which many individuals from their twenties to their nineties experience. There are two common causes of sciatic pain. Sciatic pain is most commonly caused by compression of lumbar or sacral nerve roots as they exit the spinal cord.
The most common cause for nerve compression causing sciatica in the younger population is lumbar disc herniation. It has been reported that as high as 90% of all cases of sciatic pain are due to spinal disc herniations which impinge upon the nerve roots where the sciatic nerve originates. The compression or pressing of the nerve roots can cause pain, tingling, muscle weakness, or poor muscle control of the areas supplied by the sciatic nerve. Individuals with lumbar disc herniations, also known as lumbar disc bulges or slipped discs, usually experience increased radiating sciatic pain with forward bending and sitting. Work and daily activities often become limited.
Physical therapy and instruction in patient specific exercises to reduce discal nerve impingement and to increase spinal flexibility and core strength have consistently shown to decrease and eliminate sciatic and lumbar pain. The McKenzie approach is a widely used physical therapy regimen. In this approach patients repeatedly perform specific exercises which mechanically reduce the process of disc herniation as discal material (nucleus propulsus) is pressed away from the irritated nerve roots and back toward or into the outer casing of the disc (annulus fibrosus). Treatment then focuses on strengthening postural muscles of the spine and trunk to limit the possibility of symptom recurrence.
The second most common cause of sciatic pain is lumbar spinal stenosis. Most people with lumbar spinal stenosis are over the age of fifty. It is estimated that more than 400,000 people in the United States have leg and/or lower back pain which is attributed to lumbar stenosis. The term stenosis means “choking” and is the result of the spinal cord or nerve roots being compressed within the spinal column. Stenosis is often the result of joint and disc degeneration. Sciatica from lumbar spinal stenosis usually progresses slowly and often becomes more severe with time. The low back pain and radiating buttock or leg pain will often subside for periods but, unfortunately, will often return. In most cases people with lumbar stenosis have pain with standing, walking and transitioning from a sitting to a standing position. This is due to the fact that when the lumbar spine is extended or straight, the nerve roots have less room as they exit the spinal cord and can be compressed. Patients with lumbar stenosis usually have relief when sitting and often prefer to stand with a slouched posture which reduces nerve compression and pain.
The exercise prescription for patients with lumbar spinal stenosis focuses on increasing flexibility in the spine and legs and maximizing patient walking and daily activity tolerance without worsening pain. Patients are often not able to tolerate exercise in the standing position due to the irritation of tight muscles; therefore focus is initially on loosening up those muscles to decrease symptoms. Once symptom reduction begins, the patient can usually tolerate exercises to strengthen the lower extremities, spine and trunk in positions, notably standing, where they had experienced pain during the day. The goal is to have the patient be able to perform exercises and stretches which allow them to increase their tolerance to walking and standing activities.
The third most common cause of sciatica is piriformis syndrome. In the past it was believed to cause approximately 6% of reported cases of sciatica, however recent EMG studies have shown that piriformis syndrome may be a more common source of sciatica. The sciatic nerve runs deep through the buttocks just beneath the piriformis muscle. In 10 to 15% of individuals however, it is believed the nerve runs directly through the muscle. These individuals may be at an increased risk of piriformis syndrome. Patients with piriformis syndrome usually feel worse in seated positions, as increased pressure is placed on the sciatic nerve. This is often exacerbated in individuals who sit on their wallet. Common causes are overexercising and prolonged sitting and it appears to be more common in women.
Buttock and sciatic pain resulting from piriformis syndrome respond well to physical therapy when properly diagnosed and treated. Physical therapy treatment begins with a thorough evaluation of the hip joint and spine followed by specific manual therapy techniques performed by an experienced therapist. The goal of physical therapy treatment is to allow the piriformis muscle to relax and lengthen, relieving the pressure on the sciatic nerve. Modalities including moist heat and ultrasound often assist in allowing the piriformis muscle to relax. Once pain levels are reduced, specific patient exercises and stretches can be taught, allowing patients to control and eliminate their sciatica.
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