Excision size of the occipital condyle through the far lateral suboccipital transcondylar approach: a microanatomical and clinical study

Objective To investigate the relationship between the excision size of the occipital condyle and the extent of the surgical field in the far lateral suboccipital transcondylar approach. Methods Fifteen dry skull specimen with entire skull base and 16 formalin-fixed human cadaver heads (32 sides) were collected. The visual angle was measured after a 1/3 or 1/2 excision of the occipital condyle, and the anatomical data obtained were used in the clinical treatment of 21 cases of ventral meningioma. Results The posteromedial portion of the occipital condyle affected the exposure of the lesion and needed to be partially removed. Excision of 1/3 of the occipital condyle (about 5 mm) allowed an increase of the visual angle by 15 degrees, and a 1/2 excision (about 8 mm) resulted in a visual angle enlargement by 18 degrees. Excision of the jugular tubercle allowed better exposure of the middle and inferior clivus of the ventral portion of the foramen magnum. Conclusion The excision size of the occipital condyle should be limited from 1/2 to 1/3 of its posteromedial portion, which suffices the need for exposure of the ventral portion of the foramen magnum. Key words: Far lateral suboccipital transcondylar approach; Occipital condyle; Excision size