How is GBS diagnosed?
How is GBS or Guillain-Barré syndrome diagnosed?
Guillain-Barré is called a syndrome rather than a disease because it is not clear that a specific disease-causing agent is involved. A syndrome is a medical condition characterized by a collection of symptoms (what the patient feels) and signs (what a doctor can observe or measure). The signs and symptoms of the syndrome can be quite varied, so doctors may, on rare occasions, find it difficult to diagnose Guillain-Barré in its earliest stages.
Several disorders have symptoms similar to those found in Guillain-Barré, 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 Guillain-Barré) and the quickness with which the symptoms appear (in other disorders, muscle weakness may progress over months rather than days or weeks). In Guillain-Barré, reflexes such as knee jerks are usually lost.
Because the signals traveling along the nerve are slower, a nerve conduction velocity (NCV) test can give a doctor clues to 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 a needle is inserted into the patient’s lower back and a small amount of cerebrospinal fluid from the spinal column is withdrawn for study.
Note that a quarter of all people with Guillain-Barre disease develop weakness of the breathing muscles leading to breathing and lung related failure, the inability to breathe well enough to maintain healthy levels of oxygen and/or carbon dioxide in the blood. This life-threatening situation is complicated by other medical problems such as dangerous lung disease, extreme infections, blood clots in the lungs and bleeding.