Abstract
Introduction Neurosurgical anatomy is traditionally taught via anatomic and operative atlases;
however, these resources present the skull base using views that emphasize three-dimensional
(3D) relationships rather than operative perspectives, and are frequently written
above a typical resident's understanding. Our objective is to describe, step-by-step,
a retrosigmoid approach dissection, in a way that is educationally valuable for trainees
at numerous levels.
Methods Six sides of three formalin-fixed latex-injected specimens were dissected under microscopic
magnification. A retrosigmoid was performed by each of three neurosurgery residents,
under supervision by the senior authors (C.L.W.D. and M.J.L.) and a graduated skull
base fellow, neurosurgeon, and neuroanatomist (M.P.C.). Dissections were supplemented
with representative case applications.
Results The retrosigmoid craniotomy (aka lateral suboccipital approach) affords excellent
access to cranial nerve (CN) IV to XII, with corresponding applicability to numerous
posterior fossa operations. Key steps include positioning and skin incision, scalp
and muscle flaps, burr hole and parasigmoid trough, craniotomy flap elevation, initial
durotomy and deep cistern access, completion durotomy, and final exposure.
Conclusion The retrosigmoid craniotomy is a workhorse skull base exposure, particularly for
lesions located predominantly in the cerebellopontine angle. Operatively oriented
neuroanatomy dissections provide trainees with a critical foundation for learning
this fundamental skull base technique. We outline a comprehensive approach for neurosurgery
residents to develop their familiarity with the retrosigmoid craniotomy in the cadaver
laboratory in a way that simultaneously informs rapid learning in the operating room,
and an understanding of its potential for wide clinical application to skull base
diseases.
Keywords
retrosigmoid - vestibular schwannoma - acoustic neuroma - meningioma - skull base
- education - simulation
