Inferior Approaches to the Lateral Ventricle in Children

Middle Temporal Gyrus Approach

Positioning

• Supine: The head is rotated approximately 90 degrees toward the contralateral shoulder with the help of a shoulder roll. The vertex of the head is then tilted 10 degrees downward.

Surgical Approach

• Scalp incision: A question mark or inverted U scalp incision is made starting at the base of the zygoma, 0.5 cm in front of the tragus and extending posteriorly close to the lambdoid suture.
• Craniotomy: A craniotomy large enough to allow visualization of the superior, middle, and inferior temporal gyri is used. Bur holes at the temporal squama, key hole, and posteriorly close to the lambdoid suture are used. After the bone flap is elevated, the pterion and greater wing of the sphenoid may be removed when needed (as when dealing with large tumors or when proximal control of the choroidal artery is needed). Inferiorly, the bone is removed until the opening is flush to the floor of the middle cranial fossa.
• Dural opening: The dura is opened inferiorly toward the transverse sinus.
• Cortical incision: A cortical incision in the middle temporal gyrus provides a short trajectory to the lesion, especially when the ventricles are enlarged or the temporal horn is trapped. It also provides early identification and control of the anterior choroidal artery.
• Approach to ventricle: The middle temporal gyrus is entered over its posterior and middle thirds. The white matter is divided with blunt instruments until the ependyma is seen.

 

 

 

Approach Advantages

• Short distance to lesion: A cortical incision in the middle temporal gyrus provides a short trajectory to the lesion, especially when the ventricles are enlarged or the temporal horn is trapped.
• Control of anterior choroidal artery: Provides early identification and control of the anterior choroidal artery.

Approach Disadvantages

• Risk to optic tracts: Visual field defects are the most common complications associated with this approach.
• Risk to speech: Lesion to angular and/or supramarginalis gyri may result in language and speech difficulties as well as aphasia, apraxia, and agnosia (31, 32). Dominant hemisphere injuries may be reduced with a transsulcal entry between the inferior and middle temporal gyri (36).  The lateral parietotemporal approach represents an easy way to approach the atrium. It should be restricted to the nondominant hemisphere due to the high incidence of neuropsychological and speech sequelae (11).