Patients with head and neck cancer and undergo neck dissection often suffer from spinal accessory nerve dysfunction (e.g. shoulder droop, shoulder pain, and decreased active range of motion (AROM) of the shoulder joint and scapular muscle strength), even the spinal accessory nerve is preserved during surgery. Abnormal muscle activities of scapular muscles, including upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), serratus anterior (SA) and rhomboid were reported in subsequent research articles. Particularly for the trapezius muscle, the decreased amplitudes were observed even after 9 months of neck dissection. It has been reported that conscious correction of scapular orientation during arm movement could increase trapezius muscle activities, and motor control training could change scapular kinematic such as increased posterior tilt and upward rotation during arm movement.

Patients with head and neck cancer and undergo neck dissection often suffer from spinal accessory nerve dysfunction (e.g. shoulder droop, shoulder pain, and decreased active range of motion (AROM) of the shoulder joint and scapular muscle strength), even the spinal accessory nerve is preserved during surgery. Abnormal muscle activities of scapular muscles, including upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), serratus anterior (SA) and rhomboid were reported in subsequent research articles. Particularly for the trapezius muscle, the decreased amplitudes were observed even after 9 months of neck dissection. It has been reported that conscious correction of scapular orientation during arm movement could increase trapezius muscle activities, and motor control training could change scapular kinematic such as increased posterior tilt and upward rotation during arm movement.

The aim of this study is to explore the effects of electromyographic (EMG) visual feedback on scapular muscle activities and strength in oral cancer survivors with spinal accessory nerve dysfunction. Investigators will recruit 60 newly diagnosed oral cancer subjects through the plastic surgeon's referral from January 2020 to February 2021. The participants will be randomized separated into experimental or control group. Each group would receive regular physical therapy for shoulder function (e.g. transcutaneous electrical stimulation, shoulder joint range of motion exercise) and scapular-focused exercise. EMG visual feedback would be combined with scapular-focused exercise.

Inclusion Criteria:

• newly diagnosed oral cancer subjects with neck dissection
• age between 20 and 65 years
• having the clinical signs of neck-dissection related shoulder dysfunction (e.g. shoulder droop, limited AROM of shoulder abduction, and insufficient muscle strength of shoulder abduction to against gravity)

Exclusion Criteria:

• were pregnant or breastfeeding
• had distant metastasis or recurrence
• were unable to communicate or comprehend the questionnaires
• had a history of shoulder dysfunction before neck dissection (e.g. shoulder pain, tendinitis, tendon rupture, shoulder capsulitis, or neuropathy)
• had any disorder that could influence movement performance
• bilateral neck dissection