Linkage syndrome” after facial palsy is one of the sequelae of facial palsy, as is facial muscle spasm after facial palsy. “When the patient’s eyes are transient, there is a slight tremor of the upper lip on the diseased side; when the patient shows the teeth, the eyelid on the diseased side is involuntarily closed, or the frontal muscle on the diseased side is contracted when the eyes are closed; there is also tearing of the diseased side of the eye when eating and chewing (crocodile tear sign), or flushing of the temporal skin, local heat, sweat secretion and other phenomena (auriculotemporal sign). The presence of linkage movements may be caused by the regeneration of nerve fibers after the lesion when they grow into the adjacent transsphincter cell pathways belonging to other functions. The pathophysiological basis of oro-ocular linkage movement after facial palsy is the misdirected regeneration of nerves, where the facial nerve fibers that originally innervate the orbicularis oculi muscle become associated with the nerve fibers that innervate the descending orbicularis muscle. Incidence of facial palsy linkage: Facial muscle linkage occurs during recovery from facial nerve palsy and also after temporal access nerve decompression. Due to the lack of objective and consistent assessment criteria and detection means, the incidence of muscle linkage after regeneration of facial nerve injury varies widely among reports, ranging from 9.1% to 55%, and its incidence correlates with the severity of facial nerve palsy at the onset. Mechanism of facial palsy linkage: The mechanism of facial muscle linkage is still unclear, for which many scholars have conducted a lot of research and put forward many hypotheses, mainly including three hypotheses of nerve fiber promiscuous regeneration, central control changes and abnormal synaptic transmission. Clinical manifestations of facial muscle linkage: Facial muscle linkage generally begins to appear 3 to 4 months after facial nerve injury, when facial nerve regeneration is significant, and worsens in the second year after injury, when facial nerve regeneration ends, occurring most often at 24 to 39 weeks and at the latest after 40 months. Facial muscle linkage is often confined to the side of the facial nerve injury and may progress to tonic spasms around the eyes, nasolabial folds, jaw, and broad neck muscles or the entire affected face, with the resultant distortion and muscle pain in the face.