The authors present a rare case of cervical myelopathy caused by dropped head syndrome. This 68-year-old woman presented with her head hanging forward. After 1 month, she was admitted to the medical service because of head drop progression. Examination of biopsy specimens from her cervical paraspinal muscles showed nonspecific myopathic features without inflammation, and isolated neck extensor myopathy was diagnosed. The patient's condition did not respond to the administration of corticosteroids. During follow up as an outpatient, the patient's head drop continued to gradually progress. At 1 year after onset, she developed bilateral weakness of the upper and lower extremities, clumsiness of the hands, and gait disturbance. A radiograph of the cervical spine obtained in a standing position showed a pronounced kyphotic deformity and instability at the level of C4-5. Magnetic resonance imaging demonstrated spinal cord compression at C-3 and C-4. The patient underwent a C3-4 laminectomy and occipitocervicothoracic fixation. Gait and hand coordination gradually improved, and she was able to walk with no support 1 month postoperatively. Surgical fixation was beneficial in this patient with dropped head syndrome, myelopathy, and cervical instability.