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Retrosigmoid intradural suprameatal approach: advantages and disadvantages from an anatomical perspective
1Department of Neurosurgery, Louisiana State University Health Sciences Center in Shreveport, Shreveport, Louisiana 71130-3932, USA.
Objective:
To assess the advantages and disadvantages of the retrosigmoid intradural suprameatal approach by studying the microsurgical anatomy. This study was performed primarily to assess the advantages of the retrosigmoid intradural suprameatal approach by measuring the amount of increased exposure it provides for lesions of the cerebellopontine and petroclival region as well as to identify the disadvantages of the approach.
Methods:
Twenty sides of 10 cadaver heads (embalmed and injected) were dissected under x3 to x40 magnification. A standard retrosigmoid craniotomy was made. The cerebellopontine cistern was entered to expose the neurovascular structures, and the internal auditory canal was opened by drilling the margin of the internal auditory meatus. After this, the suprameatal tubercle was drilled, followed by additional drilling to resect the petrous apex. The trigeminal root was mobilized completely after opening Meckel's cave. During drilling, care was taken to preserve the posterior and superior semicircular canals, petrosal sinus, and the internal carotid artery.
Results:
The approach enhanced the exposure of the cerebellopontine cistern and Meckel's cave. There was an additional exposure of 10.7 +/- 1.16 mm length of trigeminal nerve on the right side and an additional 10.7 +/- 1.25 mm on the left. This helped to mobilize and further retract the trigeminal root. Although it facilitated the view of the neurovascular structures medial to the internal acoustic meatus, the depth of exposure did not vary much from a traditional retrosigmoid approach nor did it increase the angle of exposure or the visualization of the clivus and more medially located structures.
Conclusion:
This approach is suitable for lesions mainly in the posterior fossa with some extension into the middle fossa in the anterolateral direction. The key benefits of this approach are the length of trigeminal nerve exposure and the subsequent mobilization that improves visualization of the structures medial to the internal auditory canal, to the petrous apex, Meckel's cave, and the posterior end of the cavernous sinus.
Insights
The retrosigmoid intradural suprameatal approach offers enhanced trigeminal nerve exposure for posterior fossa lesions. This microsurgical technique improves visualization of structures medial to the internal auditory canal and Meckel
Area of Science:
- Neurosurgery
- Microsurgery
- Surgical Anatomy
Background:
- The retrosigmoid approach is a standard technique for accessing posterior fossa lesions.
- Understanding anatomical variations and modifications is crucial for optimizing surgical outcomes.
Purpose of the Study:
- To evaluate the advantages and disadvantages of the retrosigmoid intradural suprameatal approach.
- To quantify the additional exposure provided by this technique for cerebellopontine and petroclival region lesions.
Main Methods:
- Dissection of 20 cadaver head sides under magnification (x3-x40).
- Standard retrosigmoid craniotomy followed by opening the cerebellopontine cistern.
- Drilling of the internal auditory canal margin, suprameatal tubercle, and petrous apex.
- Mobilization of the trigeminal root after opening Meckel's cave, preserving critical neurovascular structures.
Main Results:
- Enhanced exposure of the cerebellopontine cistern and Meckel's cave.
- Additional trigeminal nerve exposure of approximately 10.7 mm bilaterally, facilitating root mobilization.
- Improved visualization of structures medial to the internal acoustic meatus, petrous apex, and posterior cavernous sinus.
Conclusions:
- The retrosigmoid intradural suprameatal approach is beneficial for posterior fossa lesions with anterolateral middle fossa extension.
- Key advantages include increased trigeminal nerve exposure and improved visualization of medial structures.
- The approach enhances access to Meckel's cave and the posterior cavernous sinus.