X–ray imaging can create detailed images of different types of tissues. For example, an x–ray of the spine can show the vertebrae and the central nervous system. It can detect fractures, infections, dislocations, tumours, bone spurs, and disc disease and help doctors evaluate spinal curvature and defects. However, not all spinal injuries can be seen on x–rays, so doctors sometimes recommend other tests such as a CT scan, MRI, or myelogram to provide more information about the structures in the back.

CT (computed tomography) scan—sometimes referred to as a CAT scan—can show the size and shape of the spinal canal, its contents, and the structures around it. A CT scan is especially helpful for showing bone detail, including stenosis. Sometimes a CT scan is done in combination with a myelogram of the spine to provide additional information.

Myelogram is a type of x–ray study that uses a special dye to make the spinal canal and nerve roots clearer. After the area is numbed with a local anesthetic, a thin needle is used to inject the dye into the subarachnoid space (the fluid-filled space between the bones in the spinal column). It is sometimes used when other tests, such as a CT scan or MRI, do not detect the cause of the pain.

Magnetic resonance imaging (MRI) produces a three-dimensional image of body structures using powerful magnets and computer technology. It can show the spinal cord, nerve roots, and surrounding areas and can identify tumours and areas of enlargement or degeneration.

EMG (electromyogram) measures the electrical impulses in a muscle when it is at rest and when it contracts. This allows doctors to diagnose problems that damage muscles, nerves, and the places where nerves and muscles meet. Herniated disc is one of these problems. This test involves the placement of an electrode into a muscle. A wire connects the electrode to a machine that records the electrical activity in that muscle.