In some patients with a herniated disk, one of the symptoms they may experience is sciatica, where pain, tingling, or numbness travel down one or both legs. The connection between a herniated disk and sciatica has to do with the irritation and pressure that the disk causes to nearby tissues, particularly the nerves leading to the sciatic nerve. It is most common when damage has occurred in the disks between the vertebrae in the lower part of the back. The pain may come and go, depending on the patient's activities and the time of day.
When one has a herniated disk and sciatica, it is typically because the damaged or bulging disk is putting pressure on one or more of the nerve roots leading from the spine to the sciatic nerve. The injured disk may bulge in an abnormal manner so it is pushing against the spinal nerves, pinching or irritating them. This can in turn lead to pain which radiates down the spinal nerves to the sciatic nerve, which runs down the buttocks into the back of the legs. Depending on the location and severity of the disk damage, sciatica may travel only part of or all of the way down from the lower back to the foot, may affect one or both legs, and can also include weakness, numbness, or an ongoing pins and needles sensation.
Herniated disk and sciatica are most commonly experienced when the disk that has been damaged resides in the lower part of the spine. This can also impact where the sciatic pain is felt and how far it travels down the leg or legs. Damage to the disk between the bottom lumbar vertebrae and the top of the sacrum, or the L5-S1 disk, is a common cause of the problem. Herniation of the L4-L5 disk, which is between the bottom two lumbar vertebrae, can also lead to sciatica.
Though a herniated disk and sciatica is often quite painful, patients may notice that the pain is not always present. Certain movements such as bending, sitting for periods of time, or lifting may trigger irritation of the nerves by the damaged disk. Lying down, especially on one's side, may help relieve the pain for periods of time. Patients may notice their sciatica causes less discomfort in the mornings, after lying down all night, and gets progressively worse during the day as they move around and put additional stress on their backs.