DIAGNOSTIC CRITERIA

The signs and symptoms of the syndrome can be quite varied, so doctors may find it difficult to diagnose Guillain-Barré Syndrome (GBS) in its earliest stages.

Several disorders have symptoms similar to those found in GBS, so doctors examine and question patients carefully before making a diagnosis. Collectively, the signs and symptoms form a certain pattern that helps doctors differentiate Guillain-Barré from other disorders. For example, physicians will note whether the symptoms appear on both sides of the body (most common in GBS) and the rate at which the symptoms appear (in other disorders, muscle weakness may progress over months rather than days or weeks). In GBS, reflexes such as knee jerks are usually absent. Because the signals traveling along the nerve are slower, a nerve conduction velocity (NCV) test can aid the diagnosis. In Guillain-Barré patients, the cerebrospinal fluid that bathes the spinal cord and brain contains more protein than usual. Therefore a physician may decide to perform a spinal tap, a procedure in which the doctor inserts a needle into the patient's lower back to draw cerebrospinal fluid from the spinal column. The following procedures are often performed to aid in the diagnosis of GBS:

Lumbar puncture(spinal tap). A needle is inserted between two lumbar vertebrae and a sample of cerebrospinal fluid is drawn. An elevated level of protein in the fluid is characteristic of GBS.

Electromyogram (EMG). This test records muscle activity and can show the loss of reflexes due to the disease's characteristic slowing of nerve responses.

Nerve conduction velocity (NCV). This test is performed with EMG, and together, they are often referred to as EMG/NCV studies. NCV records the speed at which nerve conduction signals travel along the nerves.