Abstract
Objective: The subtemporal transtentorial approach provides excellent exposure of the middle
incisural space. A modification of the subtemporal transtentorial approach with use
of a partial mastoidectomy is presented to avoid damage to the temporal lobe as a
result of retraction as well as damage to venous structures.
Methods: Four patients, one with a superior cerebellar artery aneurysm, one with a metastatic
tumor in the midbrain, one with a tentorial meningioma, and one with a tentorial schwannoma
were treated with the present approach. After subtemporal craniotomy, all of the cortical
bone overlying the mastoid was removed. The mastoid air cells were drilled down, and
the upper part of Trautman's triangle was exposed above the level of the lateral semicircular
canal. The presigmoid dura and the temporal dura were opened and connected by incising
the superior petrosal sinus. The cerebellar tentorium was incised in a lateral-medial
direction along the angle of the tentorium.
Results: In each case, the tentorium was incised with minimal retraction of the temporal lobe
without any damage to the temporal lobe, or venous structures. The present approach
yielded excellent visualization of the lesion and adjacent neurovascular structures.
In 3 of 4 cases, the lesions were successfully treated. In the patient with a tentorial
schwannoma extending from the middle to posterior incisural space, the extreme lateral
supracerebellar-infratentorial approach was combined with the present approach.
Conclusions: Although additional partial mastoidectomy is time-consuming, it reduces the risk
of damage to the temporal lobe as a result of retraction as well as damage to venous
structures.
Key words
cerebellar tentorium - mastoidectomy - skull base - subtemporal transtentorial approach
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Correspondence
N. Hayashi
Department of Neurosurgery
Faculty of Medicine
University of Toyama
Sugitani 2630
Toyama 930-0194
Japan
Telefon: +87/76/434 73 48
Fax: +87/76/434 50 54
eMail: nakamasa@iwa.att.ne.jp