Skull Base Surgery of the Posterior Fossa

© Springer International Publishing AG 2018 27
W.T. Couldwell (ed.), Skull Base Surgery of the Posterior Fossa,
https://doi.org/10.1007/978-3-319-67038-6_2

Retrosigmoid Craniotomy and Its

Variants

Christian Bowers, Olaide O. Ajayi,

Kevin A. Reinard, Daniel R. Klinger,

Johnny B. Delashaw, Shane Tubbs,

and Zachary Litvack

C. Bowers, MD (*) • O.O. Ajayi, MD
K.A. Reinard, MD • D.R. Klinger, MD
J.B. Delashaw, MD • Z. Litvack, MD
Swedish Neuroscience Institute, Seattle, WA, USA
e-mail: [email protected];
[email protected]

S. Tubbs, PhD, PA-C
Swedish Neuroscience Institute, Neurosurgery-
Seattle Science Foundation, Seattle, WA, USA

2

Background

The retrosigmoid craniotomy is a modification of
the traditional suboccipital craniotomy, which was
first described in the literature by Frankel et al. in
1904 [ 1 , 2 ]. The suboccipital craniotomy provides
a wide view of the posterior cranial fossa from the
tentorium cerebelli to the foramen magnum.
Although new technologies and techniques have
been introduced to make the approach safer, it is a
testament to its versatility that this surgical
approach continues to be used nearly unchanged
from its original description over a century ago [ 1 ].

Indications

The retrosigmoid craniotomy provides for expo-
sure and access to extra-axial lesions in the cere-
bellopontine (CP) angle; lesions arising from the
underside of the tentorium, vascular, and cranial
nerve pathology of cranial nerves (CNs) V–XI;

and intrinsic pathology of lateral cerebellar hemi-

sphere and brainstem from mesencephalon to

pontomedullary junction [ 1 , 3 ]. Pathologies rou-

tinely accessed through this approach include

meningioma, vestibular schwannoma, and neuro-

vascular compression syndromes [ 4 – 7 ].

Anatomy

Cranial and Extradural Anatomy

The retrosigmoid craniotomy is a versatile

approach, and the position and extent of the cra-

niotomy (or craniectomy) is defined by the exact

position and type of pathology in the CP angle.

The limits of exposure are defined superiorly by

the transverse sinus, inferiorly by the foramen

magnum, medially by the anatomic midline, and

laterally by the sigmoid sinus. The surgical key-

hole for this approach is defined relative to the

asterion. Analogous to a pterional craniotomy,

the retrosigmoid approach may also be thought

of as an “asterional” craniotomy.

The asterion, a consistent bony landmark for

finding the junction of the transverse and sig-

moid sinuses, is defined as the junction of the

lambdoid, occipitomastoid, and parietomastoid

sutures. The lambdoid suture travels obliquely

from its origin at the caudal terminus of the

sagittal suture, separating the parietal and

occipital bones. It continues past the asterion as