Efficacy of Two Approaches in Cervical Single-door Laminoplasty for Spinal Canal Enlargement

The goal of this clinical trial is to learn if cervical single-door laminoplasty via the intermuscular space approach can better prevent axial symptom while reaching equal neurological outcome than the conventional approach in adults patients with cervical spondylotic myelopathy. The main questions it aims to answer are: * Can cervical single-door laminoplasty via the intermuscular space approach better prevent axial symptom than the conventional approach? * Can cervical single-door laminoplasty via the intermuscular space approach reach the neurological outcome not second to the conventional approach? If there is a comparison group: Researchers will compare the intermuscular space approach and the conventional approach of cervical single-door laminoplasty to see if the intermuscular space approach better prevent axial symptom. Participants will: * Received cervical single-door laminoplasty via the intermuscular space approach or the conventional approach once meet the indication. * Visit the clinic 1 month, 3 months, 6 months, 1 year and 2 years after the surgery. * Keep a diary of their symptoms and other unexpected conditions.