What causes numbness in the scapula?

Scapular Numbness: Causes and Clinical Approach

Numbness in the scapular region most commonly results from nerve compression affecting the dorsal branches of spinal nerves (T2-T6), cervical radiculopathy, or brachial plexus involvement, with less common causes including suprascapular nerve entrapment and referred pain from thoracic outlet syndrome.

Primary Neurogenic Causes

Notalgia Paresthetica

• Notalgia paresthetica is a nerve compression syndrome causing burning pain, itching, and/or numbness in the localized region between the spinous processes of T2 through T6 and the medial border of the scapula 1
• The compressed nerve is the dorsal branch of the spinal nerve, compressed by paraspinous muscles and fascia against the transverse process of these spinal segments 1
• This condition presents with localized sensory symptoms without motor weakness 1

Cervical Radiculopathy with Referred Symptoms

• Cervical radiculopathy can cause pain or sensory deficits in the scapular region when nerve root compression occurs at C5-C7 levels 2
• The most common causes include facet or uncovertebral joint hypertrophy, disc bulging or herniation, and degenerative spondylosis 2
• Patients typically present with neck pain accompanied by varying degrees of sensory or motor function loss in the affected nerve-root distribution 2

Brachial Plexus Involvement

• Brachial plexus invasion from malignancy (particularly lung or esophageal cancer) can cause pain and numbness from the scapula to upper arm 3
• MRI may reveal bone metastasis or lymph node metastasis causing neuropathic pain by brachial plexus compression 3
• This presents as neuropathic pain with numerical rating scales often 9-10/10, particularly severe at night 3

Suprascapular Nerve Entrapment

• Suprascapular nerve neuropathy can result from direct trauma (blow to base of neck or posterior shoulder), shoulder dislocation or fracture, or overuse injuries from repetitive overhead activities 4
• Compression typically occurs at the suprascapular notch beneath the transverse scapular ligament 4
• Patients present with posterior shoulder pain and may have weakness of shoulder abduction and external rotation 4

Thoracic Outlet Syndrome (TOS)

Neurogenic TOS (nTOS)

• Neurological symptoms of TOS include chronic arm and hand paresthesia, numbness, or weakness, which can extend to the scapular region 2
• Compression occurs at the interscalene triangle (anterior scalene muscle, middle scalene muscle, and first rib) where brachial plexus trunks pass through 2
• Anatomical variants such as cervical rib, anomalous first rib, or C7 transverse process abnormalities can cause narrowing 2
• Repetitive upper-extremity movement in activities like swimming or throwing can lead to symptoms in patients with anatomic predisposition 2

Musculoskeletal Causes

Scapulothoracic Dysfunction

• Snapping scapula syndrome presents with pain during overhead activities and is associated with audible and palpable crepitus near the superomedial border of the scapula 5
• Common causes include bursitis, muscle abnormality, and bony or soft-tissue abnormalities 5
• While primarily causing pain, associated nerve irritation can produce numbness 5

Winged Scapula with Nerve Palsy

• Spinal accessory nerve palsy (most commonly after neck surgery) is the most common cause of unilateral winged scapula, followed by long thoracic nerve palsy 6
• Dorsal scapular nerve palsy can occur with neuralgic amyotrophy and cause scapular symptoms 6
• These conditions can produce both motor dysfunction and sensory symptoms in the scapular region 6

Red Flag Symptoms Requiring Urgent Evaluation

Immediate imaging and specialist referral are warranted when scapular numbness is accompanied by:

• Progressive neurologic deficits or multifocal deficits 2
• Constitutional symptoms (fever, chills, unexplained weight loss) suggesting malignancy or infection 2
• History of cancer, particularly lung or esophageal, suggesting metastatic disease 3
• Bladder, bowel, or sexual dysfunction suggesting cauda equina syndrome 2
• Severe, intractable pain (numerical rating scale 9-10/10) particularly at night 3

Diagnostic Approach

Initial Clinical Assessment

• Document exact location of numbness relative to spinous processes and scapular borders 1
• Assess for associated motor weakness, particularly in shoulder abduction, external rotation, and scapular winging 4, 6
• Evaluate cervical spine range of motion and perform Spurling's test for cervical radiculopathy 2
• Examine for thoracic outlet syndrome with provocative maneuvers (Adson's test, elevated arm stress test) 2

Imaging Strategy

• MRI of the cervical spine without contrast is the preferred initial advanced imaging when cervical radiculopathy is suspected 2
• MRI of the brachial plexus and thoracic spine is indicated when malignancy or brachial plexus invasion is suspected 3
• Plain radiographs of the cervical spine and chest can identify bony abnormalities, cervical ribs, or masses 2

Electrodiagnostic Testing

• Electrodiagnostic examinations should be performed in patients with scapular numbness to establish exact diagnosis and identify specific nerve involvement 6
• Nerve conduction studies and electromyography can differentiate between radiculopathy, plexopathy, and peripheral nerve entrapment 6

Management Based on Etiology

Conservative Management for Nerve Compression

• Physical therapy focusing on posture correction and scapular stabilization for notalgia paresthetica and mechanical causes 5
• Nonsteroidal anti-inflammatory medications for initial pain control 5
• Pregabalin (starting at 75mg/day, titrating to 300mg/day) is effective for neuropathic pain from brachial plexus involvement 3

Surgical Intervention

• Surgical decompression of the dorsal branch of spinal nerves provides symptomatic relief for notalgia paresthetica refractory to conservative treatment 1
• Suprascapular nerve neurolysis at the suprascapular notch with section of the transverse scapular ligament for confirmed suprascapular nerve entrapment 4
• Thoracic outlet decompression for symptomatic TOS failing conservative management 2

Oncologic Considerations

• Combined radiation therapy and medical treatment (including pregabalin and controlled-release oxycodone) provides complete relief of neuropathic pain from brachial plexus invasion by malignancy 3
• Radiation therapy targets bone metastasis and lymph node metastasis causing nerve compression 3

Common Pitfalls to Avoid

• Do not dismiss scapular numbness as simple muscle strain without neurologic examination, as it may represent serious underlying pathology including malignancy 3
• Do not assume isolated scapular symptoms exclude cervical spine pathology, as referred pain patterns are common 2
• Do not delay imaging in patients with progressive symptoms, night pain, or constitutional symptoms suggesting malignancy 3
• Do not overlook anatomic variants (cervical rib, anomalous first rib) that predispose to thoracic outlet syndrome 2