Bone Degeneration or Inflammation
The bones and structures of the lumbar or sacral spine can put pressure on or irritate the roots of the sciatic nerve even if they are all structurally in the right place. When the vertebrae of the spine degenerate or when there is inflammation in the region of the sciatic nerve roots, this can narrow the facets (holes) that the nerve roots run through as they enter and exit the spine, causing sciatica.
Imaging studies do not always detect inflammation or tiny areas of bone degeneration that place pressure on a small part of the nerve. Often, imaging tests of the back/spine are normal. However, a normal imaging test does not mean a problem does not exist; it just means that the problem is not detectable using this test. The pain and other symptoms are real, and sometimes the affected nerve root may be located with a physical examination or an electromyography (EMG) or nerve conduction study (NVV), even if the imaging tests are completely normal. EMG and NCV are electrical studies that evaluate the function of specific nerves.
The sciatic nerve runs through the buttocks. This is a fairly muscular area, and muscle spasm or injury can put severe pressure on the nerve, producing pain. The most common type of muscular cause of sciatica is piriformis syndrome, which can result from injury or spasm of the piriformis muscle, a large muscle near the upper part of the sciatic nerve.
Cancer can spread anywhere in the body. Cancer, particularly cancer of the urinary or reproductive organs, can spread to the spine or to the areas surrounding the sciatic nerve itself, causing sciatica.
An infection may also spread to involve the sciatic nerve. This is a very rare cause of sciatica, and it is usually associated with cancer.
A severe injury may damage the sciatic nerve roots or may damage the sciatic nerve itself. This can affect any part of the sciatic nerve from where it begins in the back all the way down the leg to the foot.
Sciatica can be caused by a number of medical issues that damage or irritate the sciatic nerve or its roots. Once the medical team determines the cause of sciatica, then a treatment plan can be put in place to help relieve the symptoms.
Also Read: Symptoms Of Sciatica (Sciatic Nerve Pain)
Cass SP. Piriformis syndrome: a cause of nondiscogenic sciatica. Curr Sports Med Rep. 2015 Jan;14(1):41-4