Basic information
- The most useful neurosurgical approach
- Provides an adequate exposure of the entire Sylvian fissure and allows its dissection
- Probably the resident’s first craniotomy
Access to:
- The anterior cranial fossa
- Peri-sellar and suprasellar region
- Anterior third of the frontal and temporal opercula
- Orbital gyri
Keep in mind
- Consider whether the patient/location of the lesion are suitable for this type of approach
- Study carefully available images (CT, MR) to be prepared for anatomical rarities, use different section and projection
- Try to find the best route to the lesion with an avoidance of the excessive exposure and the retraction of brain tissue, otherwise use a different approach to reach the pathology
- Keep in mind the general anatomy (skin layers, temporal muscle, skull bones, brain surface, carotido-optic triangle, the circle of Willis)
- Be aware of possible slight distortion of the anatomy (patient is in the supine position and the head is rotated – effect of the gravity)
- Try to project the anatomy on the skin surface
Indications
Structures which are easily accessed through the pterional craniotomy: frontal and temporal opercula, the anterior cranial fossa, orbital gyri, peri- and suprasellar regions and vessels creating the circle of Willis.
Anatomy and important anatomical landmarks
- Skull bones – frontal, sphenoid, temporal, parietal, zygomatic, zygomatic arch, pterion
- Sphenoid wing
- Tragus, temporal muscle line
- Temporal muscle, facial nerve, superficial temporal artery, middle meningeal artery
- Brain surface (temporal, frontal lobe)
- Sylvian fissure
- Carotico-optic triangle, carotico-oculomotor triangle
- Circle of Willis
- Contralateral structures (optic nerve, carotid artery)
Positioning
- Usually, the supine position is preferred
- The head rotation is adapted to the exact location of the lesion
- Put the Mayfield fixation with sparing of the skin incision location
Body positioning – supine (0°), supine lateral (45°)
Head positioning: contralateral rotation (40°), lateral tilt (10°), extension (12°)
Red Flags
Avoid over-rotation of the neck by elevating the ipsilateral shoulder. Regardless of the position of the lesion, the malar eminence must always bet the highest point of the operating field
Surgery
1. Skin incision
Red Flags
Distance from the tragus is fundamental as a too anterior incision can damage the superficial temporal artery and, more importantly, the frontal branch of the facial nerve.