42 Tentorial Meningiomas
Jeffrey N. Bruce and Michael Lim

♦ Preoperative

• Tentorial meningiomas can arise from different areas of the tentorium which dictate very different approaches (Fig. 42.1). Approach can be divided into three categories.
  
  
  
  • Medial tentorial meningiomas: a combined approach may be necessary depending on tumor extent
    
    
    
    • Supratentorial only: subtemporal or temporal-occipital approach
      
    • Sometimes a transpetrosal approach is also necessary
      
    • Both supra- and infratentorial: subtemporal combined with presigmoid and possible trans- or retrosigmoid approach
      
    • Primarily infratentorial: retromastoid or retrosigmoid approach
    
    
  • Lateral tentorial meningiomas
    
    
    
    • Supratentor ial: usually parietooccipital craniotomies
      
    • Infratentorial: retrosigmoid approach
    
    
  • Falcotentorial meningiomas
    
    
    
    • Supratentorial: interhemispheric occipital approach
      
    • Infratentorial: supracerebellar approach
      
    • Supra- and infratentorial: often require removing the tumor from above and below the dura as well as transtentorial (e.g., occipital transtentorial approach)

Special Equipment

• Yasargil bar and Greenberg retractors
  
• Frameless stereotaxy
  
• Neurophysiological monitoring: somatosensory evoked potential, brain stem auditory evoked response, cranial nerves (in select cases)

Operating Room Set-up

• Irrigating bipolar and monopolar electrocautery
  
• Microscope
  
• Ultrasonic aspirator for large, soft tumors