Can C6-C7 compressive myelopathy cause decreased function of the musculocutaneous, median, ulnar, and radial nerves?

C6-C7 Compressive Myelopathy and Peripheral Nerve Function

Yes, C6-C7 compressive myelopathy can cause decreased function of the musculocutaneous, median, ulnar, and radial nerves due to compression of the spinal cord and nerve roots at this level. This compression affects the neural pathways that contribute to these peripheral nerves, resulting in neurological deficits in the upper extremities.

Pathophysiological Mechanism

• C6-C7 compression affects nerve roots that contribute to the brachial plexus, which forms the musculocutaneous, median, ulnar, and radial nerves 1, 2
• Compression at this level can cause both myelopathic (spinal cord) and radiculopathic (nerve root) symptoms, affecting multiple peripheral nerves simultaneously 1
• The reduced diameter of the vertebral canal due to degenerative changes and osteophytic spurs directly compresses nerve roots at one or more levels 3

Clinical Presentation of C6-C7 Myelopathy

• Patients with C6-C7 myelopathy may present with varied symptoms, including:

  • Weakness in the upper and lower extremities 2
  • Sensory disturbances in the hands and arms 2
  • Gait disturbances due to lower limb involvement 2
  • Neck pain 3

• Interestingly, some patients with C6-C7 myelopathy may lack typical hand symptoms:

  • 40% of patients may have no sensory disturbance in the upper limbs 2
  • 40% may have no muscle weakness in the upper limbs 2
  • 90% may have negative Hoffmann sign 2
  • Symptoms may predominantly manifest in the lower limbs as gait disturbance 2

Diagnostic Considerations

• MRI is the preferred imaging method for evaluating suspected nerve root impingement due to its superior soft-tissue contrast and spatial resolution 1

• Electrophysiological testing can help confirm the diagnosis:

  • Somatosensory evoked potentials (SEPs) show abnormalities in patients with cervical myelopathy 4
  • Reduction of the N13 potential amplitude indicates segmental dysfunction of the cervical cord 4
  • Central motor conduction time measured in the abductor digiti minimi may be prolonged 2

• False-positive and false-negative findings on MRI are common in suspected cervical radiculopathy 1

• Physical examination findings may correlate poorly with MRI evidence of cervical nerve root compression 1

Clinical Implications

• Most cases of acute cervical neck pain with radicular symptoms resolve spontaneously or with conservative treatment 1

• Surgical decompression is indicated for:

  • Severe myelopathy (mJOA scale score ≤12) 1
  • Progressive neurological deficits 1
  • Persistent symptoms despite conservative management 1

• Post-surgical monitoring of peripheral nerve function is important:

  • Intraoperative neurophysiological monitoring may help detect iatrogenic nerve root injury during decompression 1
  • Monitoring of median nerve somatosensory evoked potentials can be used during cervical spinal cord decompression 1

Common Pitfalls

• Misdiagnosis is possible because:

  • Patients with C6-C7 myelopathy may present with predominantly lower limb symptoms 2
  • Hand symptoms may be absent despite significant cord compression 2
  • Degenerative findings on MRI are common in asymptomatic patients over 30 years of age 1

• Relying solely on imaging without correlating with clinical symptoms may lead to unnecessary interventions 1

• Delayed diagnosis can result in irreversible neurological damage and poorer outcomes 5

Management Approach

• For mild cervical spondylotic myelopathy:

  • Either surgical decompression or nonoperative therapy (cervical collar, activity modification, anti-inflammatory medications) can be considered for the first 3 years after diagnosis 1

• For more severe myelopathy:

  • Surgical decompression is recommended with benefits maintained for at least 5 years postoperatively 1
  • The surgical approach (anterior vs. posterior) depends on the location and extent of compression 3

• Post-surgical rehabilitation:

  • Structured physical therapy is essential for optimal recovery and functional independence 3
  • Focus on improving strength, coordination, and gait to enhance quality of life 3