Spinal Accessory Nerve Palsy

Spinal accessory nerve palsy (SANP) is an abnormal shoulder condition that arises due to injury of the spinal accessory nerve. This nerve is a cranial nerve, originating from the brain and supplying the trapezius and sternomastoid muscles in the neck. The sternomastoid muscle helps in tilting and rotational movements of the head whereas trapezius muscle allows motions such as shrugging the shoulders or adduction of the scapula.


The spinal accessory nerve may get damaged due to neck trauma, wrenching injury to arm or neck, or even after surgical procedures such as lymph node biopsy, parotid surgery, carotid surgery and jugular vein cannulation.


The major symptoms associated with spinal accessory nerve palsy include:

  • Pain and weakness in shoulder
  • Altered shoulder mechanics
  • Weakness with lifting
  • Droop shoulder
  • Trapezius muscle atrophy


The diagnosis of spinal accessory nerve palsy starts with a careful medical history and physical examination of the patient. Your doctor may employ imaging techniques such as electromyography (EMG) and nerve tests, as confirmatory measures.


The treatment of spinal accessory nerve palsy includes physical therapy as the main conservative or non-surgical component. For patients not responding to the conservative methods, surgery is considered for them. Surgical options comprise nerve surgery, nerve grafting, and nerve regeneration. Other treatment options include tendon or muscle transfer to stabilize scapula, employed for patients not responding to nerve repair or surgery. One of the widely used surgical procedures is scapulothoracic fusion.

Scapulothoracic fusion

Scapulothoracic (ST) fusion is a salvage procedure performed to stabilize the scapula on the thorax. It involves the fusion of the medial border of the scapula to the underlying 3 to 5 ribs. The scapulothoracic (ST) motion plays an important role in shoulder elevation and abduction. This procedure is recommended when tendon transfer fails to treat spinal accessory nerve palsy and long thoracic nerve palsy. Other conditions that can be treated through scapulothoracic fusion include facioscapulohumeral dystrophy, medial clavicular insufficiency and brachial plexus.


The basic steps involved in scapulothoracic fusion surgery include:

  • Patient is laid on the operation table with face down and is anesthetized under general anesthesia
  • An incision is made along medial border of scapula
  • Then inner margin of the scapula bone along its full length is exposed along with underlying 3 to 5 ribs
  • Then scapula is wired to the adjacent ribs
  • Bone graft is placed at the contact point and also bone stimulator is implanted to promote fusion
  • Finally incision is closed

Usually the whole procedure takes 3-4 hours and patient may require staying in hospital for 3-5 days.

Post-operative care

The patients who have undergone scapulothoracic fusion are advised to follow some basic instructions:

  • Wear sling and avoid use of operated extremity first 6 weeks
  • Follow your therapists instructions regarding activity and exercise during healing process

It may take 6 months or up to 1 year for full functioning of the shoulder.

Risks and complications

Although scapulothoracic fusion is a safe procedure, various risks and complications have been reported that include:

  • Metalwork failure
  • Adhesive capsulitis
  • Nonunion of bone
  • Pneumothorax
  • Pleural effusion
  • Thoracic outlet syndrome
  • Pneumonia
  • Scapula fracture
  • Deep venous thrombosi