Abstract
Introduction:
Pathologies confined to the upper brainstem pose challenges to the neurosurgeon. Quantitative analysis of the surgical exposure and angle of attack for retrosigmoid (RS), lateral supracerebellar (SC), and extreme lateral supracerebellar (EL) approaches to the pontomesencephalic junction is presented.
Methods:
Eight sides of injected cadaveric heads were dissected with the three approaches. All predetermined anatomical points were correlated to a frameless stereotactic system for analysis.
Results:
The best visualization of the lateral brainstem surface was accomplished with EL, followed by SC and RS (posterosuperior margin: RS 4.3 ± 1.7 mm, SC 6.4 ± 1.9 mm, EL 7.3 ± 2.0 mm; posteroinferior margin: RS 2.7 ± 2.7 mm, SC 4.9 ± 2.8 mm, EL 8.3 ± 2.5 mm). With an intact tentorial edge, the effect of venous retraction by EL approach was significantly greater over the SC approach at the anteroinferior margin (p < 0.05) and posteroinferior margin (p < 0.001). The working area was horizontally oriented in the SC and EL craniotomies and vertically oriented in the RS exposure.
Conclusion:
Mobilization of the sinuses as performed in the EL approach augments the vertical working area of the lateral brainstem compared with the SC. Supracerebellar trajectories provide greater exposure of the posterolateral pontomesenceaphalic junction compared with RS.