====== Dolenc approach ======

{{::pterional_craniotomy.png?400|}}

The resulting [[bone flap]] is centered over the depression of the [[sphenoid ridge]]. Approximately 33% of the craniotomy is anterior to the anterior margin of temporalis muscle insertion, ≈ 66% is posterior.

With the [[craniotome]], starting at the frontal [[burr hole]] the [[craniotomy]] is taken anteriorly across the anterior margin of the [[superior temporal line]], staying as low as possible on the [[orbit]] (to obviate having to rongeur bone, which is unsightly on the forehead). The distance “B” from the medial extent of the craniotomy to the frontal burr hole is 3 cm for [[anterior circulation aneurysm]]s. For the approaches to [[skull base]] (e.g. [[Dolenc approach]]), distance “B” is larger and takes the opening to ≈ the mid orbit. Then from point “B,” a sharp superior turn is made and the opening is taken back to point “A.” The height (“H”) of the craniotomy needs to be only ≈ 3 cm for aneurysms of the [[Circle of Willis]], and slightly larger (≈ 5 cm) for the [[middle cerebral artery aneurysm]]s. Minimal exposure of the [[temporal]] cortex is necessary for aneurysms of the skull base region. For large flaps (e.g. for tumors), “H” is made larger to expose more temporal lobe.