OBJECTIVE: To investigate the effect of endoscopic dissociation of the sternocleidomastoid muscle in the treatment of myotonic leptomeningeal neck. METHODS: In 23 children with myotonic squamous neck, aged 1 month to 12 years, with a median of 2 years and 6 months, a 5-mm trocar was placed in the right axillary skin line, and the muscle membrane on the surface of the sternocleidomastoid head and clavicle head at the lower end of the sternocleidomastoid muscle was bluntly separated with a hand-held lens and filled with CO2 gas and pressurized to 6 mm Hg to form a subcutaneous space. A 3-mm curved forceps and an electrodebrider tip were placed in a 3-mm incision within the lateral subcervical transverse stripe and in the anterior thoracic transverse stripe, respectively. The fibrous bundle of the sternocleidomastoid muscle was transected by electrocoagulation or electrodissection, and the fibrous tissue around the sternocleidomastoid muscle was released. Results: All 23 cases were operated endoscopically. The average operation time was 51.2 min (35-135 min), and the intraoperative bleeding was <1 ml. There was no damage to the surrounding large vessels and nerves. After the operation, neck stretching activity training was performed, and the patient was discharged on the first postoperative day. 23 cases were followed up from 3 months to 4 years, with a median time of 6 months, and the oblique neck was corrected in all cases, with excellent results in 18 cases and good results in 5 cases, with no obvious incision scar, good skin elasticity, no abnormal activity with expression, and no recurrence. Conclusion: Endoscopic sternocleidomastoid excision has the advantages of minimally invasive, fast recovery, good results, inconspicuous scar, aesthetic and no damage to the broad neck muscle, and no effect on expression activities.