Magnetic resonance imaging of the cervical spine is read as normal by the radiologist. You then decide to obtain an MRI of the thoracic and lumbar spine. The thoracic spine MRI is shown in Fig. 92.1. The lumbar MRI is read as normal.

• The differential diagnosis of spinal progressive myelopathy is broad and includes the following1,2 (for a more detailed diagnosis list, please refer to Case 87):
  
  
  
  • Syringomyelia
    
  • Postviral conditions
    
  • Vertebral osteomyelitis
    
  • Traumatic fracture
    
  • Spinal cord tumor
    
  • Epidural lipomatosis
    
  • Degenerative conditions: spondylotic myelopathy, ossified posterior longitudinal ligament, disk herniation
    
  • Multiple sclerosis transverse myelitis or Guillain-Barré syndrome
    
  • Spinal epidural, subdural, or subarachnoid hematoma, spinal cord infarction

• Imaging studies
  
  
  
  • Plain radiographs
    
  • MRI
    
    
    
    • Study of choice
      
    • Noninvasive
      
    • >95% effective in diagnosis of myelopathy
    
    
  • Computed tomography (CT) and/or CT myelogram
    
    
    
    • When MRI cannot be done
      
    • In cases where resolution of MRI is low
      
    • Plain CT good for C5–C6 but poor for C6–C7 or below due to shoulder artifact
      
    • CT myelogram has 98% accuracy but requires overnight admission
      
    • In thoracic disk herniations, CT scan helps to evaluate the extent of calcifications.

• Classification by level^3,4
  
  
  
  • T1–T4, or upper thoracic spine
    
    
    
    • Thoracic outlet and superior mediastinum
    
    
  • T5–T9, or middle thoracic spine
    
    
    
    • Stabilizing influences of the rib cage
    
    
  • T10–T12, or thoracolumbar spine
    
    
    
    • Transition zone of vertebral configuration
  
  
• Classification by laterality⁴
  
  
  
  • Midline
    
  • Paramedian
    
  • Lateral

• Conservative measures⁴
  
  
  
  • Analgesics, muscle relaxants, nonsteroidal antiinflammatory drugs
    
  • Limited activity, bed rest for 1 to 2 weeks
    
  • Physical therapy — extension exercises and paraspinal muscle strengthening
    
  • Stretching and muscle relaxation with heat, ultrasound, or transcutaneous electrical stimulation
    
  • Bracing (thoracolumbar spinal orthosis brace)
    
  • Short course of oral steroids
    
  • Epidural steroid injections
  
  
• Surgical measures – indications^4,5
  
  
  
  • Failure of conservative measures
    
  • Severe symptoms of pain or myelopathy
    
  • Progressive deterioration in symptoms

• Surgical treatment is the most appropriate approach in this case.
  
• This is due to the severity of the symptoms and signs of myelopathy.

• Approaches for thoracic disk herniations^4–9
  
  
  
  • Posterior midline laminectomy
    
    
    
    • Ease and familiarity of anatomy and approach
      
    • Disadvantages
      
      
      
      • Unacceptably high failure rate in single level anterior pathology
        
      • Neural injury
        
      • Inadequate decompression
        
      • Not a generally accepted approach for most thoracic disks
  
  
• Posterolateral approach: transpedicular or transfacet — pedicle sparing
  
  
  
  • Laminectomy, removal of pedicle and medial facetectomy
    
  • Good results for lateral herniated disk
    
  • Do not require transpleural or transmediastinal dissection
    
  • No violation of the rib cage or ligation of the neurovascular bundle
    
  • Potential for less operative time and bleeding
    
  • Familiar to most neurosurgeons
    
  • May be done endoscopically
    
  • Disadvantages
    
    
    
    • Limited visibility of the midline of the anterior spinal canal
      
    • Unable to completely remove disks that are mainly central or past the midline
      
    • Possible instability with removal of pedicle/facet complex
  
  
• Costotransversectomy
  
  
  
  • Good for lateral disk herniation
    
  • Resection of transverse process and 4–8 cm of rib
    
    
    
    • Rib that articulates with the inferior vertebra of the disk level to be treated
    
    
  • Ligation of intercostal nerve ~3 cm distal to dorsal root ganglion
    
  • Direct visualization of neural elements
    
  • Disadvantages
    
    
    
    • Risk of interrupting radicular artery, which supplies blood to spinal cord
      
    • Risk of intercostal neuralgia or anesthesia dolorosa
      
    • Manipulation of intercostals muscles
  
  
• Lateral extracavitary approach
  
  
  
  • Enables total resection of centrally located disks
    
  • Good for central soft and calcified disks
    
  • Ease of multilevel exposure
    
  • No need for chest tube drainage if pleura preserved
    
  • Disadvantages
    
    
    
    • Extensive procedures and bony resection
      
    • High operating times, blood loss
      
    • Significant perioperative pain and physiologic stress to the patient
  
  
• Anterolateral transthoracic approach
  
  
  
  • Good for central disk or when myelopathy is present → best operative results
    
  • Good exposure obtained from T4–5 to T11–T12
    
  • Right-sided thoracotomy preferred for midthoracic because heart does impede access
    
  • Left-sided preferred for lower thoracic (easier to mobilize aorta than vena cava)
    
  • Low risk of mechanical cord injury
    
  • Little compromise of stability
    
  • Disadvantages
    
    
    
    • Requires thoracic surgeon
      
    • Extensive, time-demanding procedure
      
    • Risk of vascular cord injury
      
    • Pulmonary complications and cerebrospinal fluid (CSF) pleural fistula
      
    • Postthoracotomy pain syndrome
      
    • Closed chest drainage is required postoperatively.
      
    • Mediastinal structures are at increased risk.
      
    • Hard to access disks above T4–T5
  
  
• Video-assisted thoracoscopic approach
  
  
  
  • Minimally invasive
    
  • Avoids pulmonary complications and morbidities
    
  • Less blood loss
    
  • Can access centrally located disk herniations
    
  • Prevents denervation of paraspinal musculature
    
  • Less bone resection
    
  • Disadvantages
    
    
    
    • Requires thoracic surgeon
      
    • High level of technical skill and steep learning curve
      
    • Limited ability to strut graft or fuse anteriorly
      
    • Difficult to repair CSF leak

• Any of the approaches described above are appropriate except for laminectomy.
  
• In this case, a posterolateral approach via costo-transversectomy was selected. Postoperative MRI is shown in Fig. 92.2 and Fig. 92.3 for illustration of the approach.
  
• The reasoning behind this selection: the patient is young and the disk is more likely noncalcified and the disk is lateral to paramedian.

• Overall outcomes^9–12
  
  
  
  • Posterior midline laminectomy: 32% worse outcome, 57% improved or stayed the same
    
  • Posterolateral approach: 7% worse outcome, 82% improved or stayed the same
    
  • Endoscopic transpedicular: 90% improvement (n = 25)⁹
    
  • Costotransversectomy: 0% worse, 12% same, 88% improved
    
  • Anterolateral transthoracic approach: 0% worse, 94% pain improved, 97% myelopathy improvement

• Indications for fusion⁴
  
  
  
  • Multilevel disk resection
    
  • Kyphosis
    
  • Wide vertebral body segment resection affecting stability
    
  • Junctional level (T12–L1)