What are the best practices for lateral skull base approaches?

Best Practices for Lateral Skull Base Approaches

Advanced imaging with MRI and CT is essential for successful lateral skull base approaches, with surgical technique selection based on lesion location, extent, and pathology. 1

Imaging Considerations

MRI

• Primary imaging modality for evaluating:
  • Brainstem and intracranial nerve courses
  • Soft tissue characterization
  • Perineural tumor spread
  • Neurovascular compression syndromes

• Recommended sequences:
  • Pre- and post-contrast imaging for optimal lesion characterization
  • Thin-cut heavily T2-weighted sequences
  • Contrast-enhanced modified balanced SSFP sequences
  • High-resolution 3D T2-weighted imaging 1

CT

• Complementary to MRI for evaluating:
  • Skull base erosion
  • Bony foramina anatomy
  • Intratumoral calcification
  • Surgical planning for bony landmarks

• Protocol should include:
  • Thin-cut high-resolution bone windows
  • Contrast enhancement for soft tissue evaluation 1

Approach Selection

Pterional Approach

• Best for: Cavernous sinus lesions
• Considerations: May be combined with orbitozygomatic osteotomy for enhanced exposure 1

Retroauricular Approach

• Best for: External auditory canal lesions
• Considerations: Common for accessing lateral skull base 1

Endonasal Approach

• Best for: Midline skull base lesions
• Considerations: Excellent visualization with minimal invasiveness using powered, miniaturized instrumentation 1

Combined Micro-Endoscopic Approach

• Benefits:
  • Stereoscopic vision and magnification
  • Bimanual surgical manipulation
  • Angled vision capabilities 1
  • Allows for less traumatic dissection of deeper structures 1

Surgical Planning Considerations

Preoperative Assessment

• Multiplanar CT scans with 3D reconstructions are strongly recommended to tailor the intervention to individual pathology 1
• Consider using cadaver laboratories for practicing approaches before actual surgery 1

Endoscopic vs. Microscopic Considerations

• Endoscopy advantages:

  • Enhanced visualization around corners
  • Less traumatic dissection of deeper structures
  • Wider field of view

• Microscopy advantages:

  • Straight-on view in line with trajectory
  • Better depth perception
  • Allows visual control of endoscope 1

Combined Approaches

• Endoscopy-assisted microneurosurgery may be useful in selected cases
• Operative microscope provides straight-on view while endoscope offers around-the-corner visualization 1

Complication Avoidance

Major Risks

• Vascular injury (particularly to internal carotid artery)
• Cranial nerve damage
• CSF leak
• Infection 1

Risk Reduction Strategies

• Careful patient selection
• Thorough review of preoperative imaging
• Meticulous surgical technique
• Appropriate reconstruction methods 2

Special Considerations

Tumor Resection

• Gross total resection is achievable in approximately 80% of benign skull base tumors, even in challenging locations like the cavernous sinus 1
• For highly vascularized tumors, consider staged approaches or preoperative embolization 1

Pediatric Patients

• CT examination should be used cautiously due to radiation exposure to the thyroid gland
• MRI is preferred when available and can be extended to include the mediastinum 1

By following these best practices for lateral skull base approaches, surgeons can optimize outcomes while minimizing morbidity and mortality in this challenging anatomical region.