1. LUMBAR PUNCTURE (Spinal Tap) - The patient is given local anesthetic. Once the anesthetic has taken effect, a needle is inserted between two lower (lumber) vertebrae & sample of cerebrospinal fluid is drawn. An elevated level of protein in the fluid is characteristic of GBS.
2. ELECTROMYOGRAM (EMG) - This is an effective diagnostic tool because it records muscle activity & can show the loss of reflexes due to the disease’s characteristic slowing of nerve responses.
3. NERVE CONDUCTION VELOCITY (NVC) - This test is performed with EMG, & together they are often referred to as EMG/NCV studies. NVC records the speed at which signals travel along the nerves.
The first symptoms of GBS are usually numbness or tingling (paresthesia) in the toes and fingers, with progressive weakness in the arms and legs over the next few days. Some patients experience paresthesia only in their toes and legs; others only experience symptoms on one side of the body. The symptoms may stay in this phase, causing only mild difficulty in walking, requiring crutches or a walking stick. However, sometimes the illness progresses, leading to complete paralysis of the arms and legs. About one quarter of the time, the paralysis continues up the chest and freezes the breathing muscles, leaving the patient dependent on a ventilator. If the swallowing muscles are also affected, a feeding tube may be needed. Back pain affects around 30%. Facial muscles and breathing can also be affected.
In CIDP, the course of illness is longer and respiratory failure is much more unlikely. CIDP usually shows signs of weakness in the legs over a longer period of time, & can be repetitive.
Because its symptoms vary and its cause is unknown, GBS can be difficult to diagnose. If the symptoms occur uniformly across the body and progress rapidly, the diagnosis is easier.
Observation of the patient's symptoms and an evaluation of the medical history provide the basis for diagnosis of Guillain-Barre syndrome, although no single observation is suitable to make the diagnosis. The patient's symptoms and physical exam are usually sufficient to indicate the diagnosis. The rapid onset of (ascending) weakness, frequently accompanied by abnormal sensations that affect both sides of the body similarly. Loss of reflexes, such as a knee jerk, are usually found. To confirm the diagnosis, a lumbar puncture to find elevated fluid protein and electrical tests of nerve and muscle function may be performed.