The onset of symptoms is rapid, progressing steadily for a period of days to weeks. The symptoms will then stabilize at this level for a period of days to weeks to even months. The next phase, known as the recovery phase, is also variable among affected persons. This phase may last from a few weeks to months. At the end of the recovery phase, individuals may experience complete recovery from the disorder, or they may experience some degree of weakness that does not resolve.
Diagnosis can sometimes be difficult.
This is especially true in the early stages because of the variability from one person to another of both the symptoms and the severity of those symptoms. A detailed history is the first step to diagnosis, followed by a complete physical examination. A nerve conduction velocity test can alert the physician to slowness of signals traveling along the nerve pathways. A spinal tap may be done to examine the cerebrospinal fluid for abnormalities. Reflexes are often absent in GBS, so careful testing of the reflexes is useful.