Guillain-Barré Syndrome Presenting With Masticatory Disturbance and Reduction in Bite Force.

Guillain-Barré syndrome is a rare, rapidly progressive, and potentially fatal immune-mediated neuropathy. A 17-year-old male patient with a fever of 38°C developed masticatory impairment a few days later. Although the fever resolved after one week, the restricted mouth opening and decreased bite force persisted. Thirty-five days after disease onset, the patient was referred to our clinic and reported severe masticatory dysfunction due to a significant reduction in maximum bite force (left: 0 N, right: 12.7 N). His maximal mouth opening was 24 mm without jaw deviation. An electrophysiological study revealed Guillain-Barré syndrome (acute motor axonal neuropathy). The patient was closely monitored as he underwent rehabilitation comprising mouth opening and mastication training. The patient's bite force and masticatory impairment due to the weakness of the muscles of mastication gradually improved. At one year and five months after disease onset, the masticatory impairment had fully resolved. His maximum bite force two years after disease onset was 158.3 N on the left side and 172.2 N on the right side.