Although the exact mechanism for<unk>  is still unclear, understanding what is affected with this syndrome is important. The majority of cases are thought to occur when nerve bundles in the head and neck are injured. Such bundles are able to send an action potential from the autonomic nervous system to the rest of the body. However, action potentials in this system are not being received by the second or third thoracic vertebrae which innervates the face, neck, and upper chest. Damage or lesions near T2 or T3 could be between the stellate ganglion and superior cervical ganglion. This is where we would observe absence of sweat and skin flushing on one side of the face, neck, and upper chest.
Harlequin syndrome
Pretzel syndrome
Rapunzel syndrome
Keutel syndrome
Irlen syndrome
Sly syndrome
Stauffer syndrome
STAR syndrome