Sciatica: What Causes It And What Can You Do About It?

By Dr. James Cassell, PT, DPT

Sciatica is a very common symptom of injuries that brings patients into my physical therapy clinic. Sciatica is aggravation of the sciatic nerve, resulting in radiating pain from the low back, into the buttock and down the back of the leg. This symptom can be caused by numerous conditions, and I will go over a few of the most common injuries that I see on a daily basis: bulging/herniated discs, spinal stenosis and piriformis syndrome.

The first common cause of sciatica is bulging/herniated discs. Before explaining how this injury leads to sciatic, I will describe the spinal cord and how the injury can occur. The spinal column is an alternating sequence of a solid bone (vertebra) and a softer disc. This alternating pattern allows for the spine to bend, straighten and rotate. The sciatic nerve is composed of nerve roots from 5 different levels in the spine, which means that compression at any of those levels can cause sciatica symptoms. Bulging discs and herniated discs are very similar, in the sense that a herniated disc is a more severe version of a bulging disc. A bulging disc occurs when the soft material inside a disc is pushed backwards and compresses one or multiple nerves near where they connect to the spinal cord. The nerves that are compressed become aggravated and can give the patient pain sensations at any point along the nerve. Pain symptoms may manifest as shooting, tingling, numb or aching to name a few. A herniated disc also compresses on the nerves in the low back, though the soft material within the disc tears through the more supportive outer layer, rather than merely expanding it, as with a bulge. These symptoms are typically worsened when leaning forward or sitting, as this pushes the disc material backwards even more, increasing nerve root compression.

Another injury I frequently see cause sciatica in my patients is spinal stenosis. Spinal stenosis occurs when the nerve root is compressed by bone as it leaves the spinal column. The nerves travel through a hole between the vertebra above and below it, called a foramen. These foramen can become smaller, either from bone buildup, generally due to chronic overuse/injury, or due to the discs gradually wearing away and losing their height. The symptoms are similar to a disc issue, as nerve roots are still being compressed, however spinal stenosis tends to be aggravated with standing and leaning backwards, as this closes the foramen space even further. Patients with spinal stenosis tend to report reduction in their symptoms when leaning forward, as this increases foramen space, and reduces nerve compression.

The last common injury I’m going to discuss is piriformis syndrome. The piriformis muscle is a fan-shaped muscle that runs horizontally from the sacrum (base of the spine) to the top of the femur (leg bone). It runs deep to the gluteal muscles. The piriformis can cause sciatica, because the sciatic nerve runs just underneath the piriformis, directly through the piriformis or the piriformis muscle can sometimes split the sciatic nerve. If the piriformis becomes aggravated, it can compress on the sciatic nerve. The piriformis muscle is an external rotator of the hip and a hip stabilizer, it works in conjunction with the gluteal muscles. If a patient has weak gluteals, the piriformis may become overused and spastic/tight, causing sciatic nerve irritation. This can be differentiated from the aforementioned injuries, as piriformis syndrome doesn’t typically change with low back movements.

All three of the injuries described above can be treated conservatively with physical therapy, chiropractic and massage therapy. With disc bulges/herniations and spinal stenosis, treatment would focus on stretching and massaging any tight muscles, while strengthening the stabilizing muscles around the spine. Patients may also perform repetitive movements to try to push disc material into the correct location or to open the foramen further. Finally, piriformis syndrome is treated by stretching and massaging the piriformis and gluteals, while also strengthening the gluteals to reduce pressure on the piriformis.


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