The diagnosis of sciatica usually involves a thorough medical history and a physical examination with certain tests to establish the involvement of the symptoms. In some cases, further medical test may also be required to differentiate sciatica from other health conditions with similar symptoms that require other treatments.
A full medical history should be taken to establish any important information that may have led to the development of the presenting symptoms.
The symptoms of sciatica may include, pain, numbness or a tingling sensation (pins and needles). It usually affects the lower back, buttocks and various areas down one leg. While it may affect both sides, sciatica is typically unilateral as it is caused by pressure on the nerves.
Any particular circumstances that may be associated with a more serious cause of the presenting symptoms should also be discussed. Possible conditions that may be confused with symptoms of sciatica include:
- Cauda equina syndrome – symptoms concentrated in buttocks and groin area with recent loss of bladder or bowel control
- Spinal infection – additional symptoms of fever and chills or recent urinary tract infection
- Spinal fracture – usually associated with recent physical trauma and pain is usually relieved by lying down
- Tumor – more common in presenting individuals aged older than 50 or younger than 20 and with a previous history of cancer
There are several physical tests that may be conducted in order to determine if the patient has symptoms of sciatica. It is worthwhile to test muscle strength and reflexes in the examination.
For example, the patient can be asked to walk on their toes or heels and describe if their pain worsens. Additionally, rising from a squatting position is usually more painful for those that suffer from sciatica.
The straight-leg-raising test is an excellent way to indicate if sciatica is present. In this test, the patient should be asked to lay down flat on their back and one leg should be lifted up into the air at a time. If the process of lifting the leg causes the pain and other symptoms to worsen, it is likely that sciatica is to blame.
In most cases, the medical history and physical exam provide sufficient information to make a diagnosis of sciatica. However, some individuals present with particular risk factors that require further investigation to differentiate the condition from others with more serious consequences, such as an infection, fracture, cancerous tumor or cauda equina syndrome.
For these patients, medical imaging is often utilized to determine the cause of the symptoms and increase the probability of a correct diagnosis. These are also indicated for patients with severe or persistent symptoms.
- An X-ray of the spinal region can reveal herniated disks or bone spurs that press on a nerve to cause symptoms. Some patients without symptoms may have an X-ray that shows this, but do not usually require treatment unless symptoms present.
- Magnetic resonance imaging (MRI) allows the production of cross-sectional images of the back with details of the bone and soft tissues, including herniated disks.
- Computed tomography (CT) scan and be used with a contrast dye to visualize the spinal cord and nerves in the area.
- Electromyography (EMG) is a test to measure the electrical impulses that result from the nervous system, providing information about the spinal cord and any narrowing of the canal.
Some patients may also call for a blood test if the cause of the symptoms is unclear and another health condition is suspected to be involved.