“Many of the body’s nerves are like household wires. There is a central conducting core in the nerves called the axon that carries an electric signal. The axon (an extension of a nerve cell) is surrounded by a covering, like insulation, called myelin. The myelin sheath surrounding the axon speeds up the transmission of nerve signals and allows the transmission of signals over long distances.
Since nerves are damaged in GBS, the brain may receive abnormal sensory signals from the rest of the body. This results in unexplained, spontaneous sensations, called paresthesias, that may be experienced as tingling, a sense of insects crawling under the skin (called formications), and pain. Deep muscular pain may be experienced in the back and/or legs.”.
(National Institute of Neurological Disorders and Stroke at https://www.ninds.nih.gov/)