Staged Cranial Surgery for Intracranial Lesions: Historical Perspective.

We follow the development of staged resection from its first description by Walter E. Dandy, one of the founding fathers of neurosurgery, in 1925 in which he removed a large vestibular schwannoma.This historical vignette cites neurosurgical case reports and literature to demonstrate the evolution of staged resection of intracranial lesions, from Dandy's initial use to its becoming a more viable and safe option for the treatment of meningiomas, vestibular schwannomas, and skull base lesions (among numerous other intracranial pathologies). We also discuss the current advancements and future perspectives of staged resection that may show promise in effectively treating a wide range of pathologies while simultaneously reducing morbidity rates-a warrant for further exploration of staged cranial surgery as an important tool in neurosurgery.

Evolution of techniques for the resection of vestibular schwannomas: from saving life to saving function.

The current state of surgery for vestibular schwannomas (VSs) is the result of a century of step-by-step technical progress by groundbreaking surgeons who transformed the procedure from its hazardous infancy and high mortality rate to its current state of safety and low morbidity rate. Harvey Cushing advocated bilateral suboccipital decompression and developed the method of intracapsular tumor enucleation. Walter Dandy supported the unilateral suboccipital approach and developed the technique of gross-total tumor resection. Microsurgical techniques revolutionized VS surgery to its current status. In this article, the authors review the early history of surgery for VSs with an emphasis on contributions from pioneering surgeons. The authors examined the Cushing Brain Tumor Registry for clues regarding the bona fide intention of Cushing for the resection of these tumors.

History of vestibular schwannoma surgery.

Attempts of surgical removal of vestibular schwannomas started 150 years ago with major limitations in terms of diagnosis and understanding of the disease but also in respect of surgical technique and instrumentation. Then came Cushing followed by Dandy, two pioneers and legendary neurosurgeons who understood the natural history of the disease and set the landmarks of the current surgery of the cerebellopontine angle. In this century of medicine, results and expectations shifted from a life-threatening affection to the actual standard of cranial nerve preservation and conservation of quality of life. In this overview, it is shown how the standard of the current surgery came from two distinct medical cultures, otologists and neurosurgeons, respectively. Now and in the near future, these competencies will be gathered in multidisciplinary teams who will display the whole panel of the treatment options in order to offer the best individual solutions for the patients.

Microsurgical anatomy of acoustic neuroma. 2002.

This article reviews the microsurgical anatomy important to preserving the involved cranial nerves and adjacent neural and vascular structures during acoustic neuroma removal. These anatomic considerations are divided into sections dealing with the relationships at the lateral end of the tumor in the meatus and those on the medial end of the tumor at the brain stem. The anatomy of the region offers the opportunity for three approaches to the tumor in the meatus and cerebellopontine angle. One is directed through the middle cranial fossa and the roof of the meatus. Another is directed throught the labyrinth and posterior surface of the temporal bone. The third is directed through the posterior cranial fossa and posterior meatel lip. The anatomy presented by all three approaches is reviewed in this article.

Imaging of acoustic neuromas. 1992.

Diagnosis of acoustic neuromas has been simplified considerably by computed tomography (CT) and magnetic resonance imaging (MRI). Either enhanced method will visualize almost every acoustic neuroma. MRI is more sensitive inside the internal auditory canal. Currently, a gadolinium-enhanced MRI scan is considered an accurate indicator of whether or not an individual has an acoustic neuroma, although there have been false-positive enhanced MRI scans recently reported.

Conservative management of acoustic neuromas. 1992.

An expectant, nontreatment strategy for acoustic neuromas implies an understanding of the natural biologic behavior of these tumors. This study describes the long-term follow-up of a group of unoperated acoustic neuroma patients. Patterns of tumor growth are discussed in light of clinical outcome. Patient selection and a follow-up protocol are recommended for those individuals in whom a nontreatment strategy is contemplated.

Selection of surgical approach to acoustic neuroma. 1992.

A variety of surgical approaches are available in the management of acoustic neuroma. Each procedure has certain advantages and disadvantages in terms of surgical exposure, the capability of preserving cranial nerve function, and postoperative morbidity. This article advocates tailoring the operative approach to each acoustic neuroma according to its size, location, and clinical manifestations.

Retrosigmoid approach for acoustic tumor removal. 1992.

The retrosigmoid technique has evolved from the traditional suboccipital operation and, when combined with removal of the posterior wall of the internal auditory canal (IAC), affords a wide exposure of the cerebellopontine angle. This approach may be used for acoustic neuromas of all sizes, from intracanalicular, to more than 4 cm from the porus acusticus. Hearing preservation may be attempted and is generally successful in a substantial minority of cases. The facial nerve is readily visualized at the lateral end of the IAC and is at no greater risk than in the translabyrinthine operation. The authors use this approach for all hearing preservation surgery as well as for tumors of more than 3 cm, regardless of hearing.

Translabyrinthine approach for acoustic tumor removal. 1992.

The translabyrinthine approach is the most direct route to the cerebellopontine angle. It is the preferred approach for removal of all tumors in patients with poor hearing and for large tumors when the likelihood of hearing preservation is slight. This approach offers the advantages of minimum cerebellar retraction, identification of the facial nerve proximally and medially, and the ability to repair immediately the facial nerve if it is severed during acoustic tumor removal. This approach has the lowest morbidity with regard to spinal fluid leaks and also postoperative headaches.

Transotic approach to the cerebellopontine angle. 1992.

The transotic approach to the cerebellopontine angle has been developed at the University of Zurich for the removal of acoustic tumors in an effort to increase operative exposure and enhance facial nerve preservation and reconstruction. Key steps involve the total removal of all pneumatic cell tracts with middle ear and eustachian tube obliteration, followed by complete otic capsule removal for tumor exposure. This article discusses the advantages, disadvantages, and technique of this approach.

Middle fossa approach for acoustic tumor removal. 1992.

The middle fossa approach is useful for the removal of small acoustic tumors when hearing preservation is possible. This approach provides complete exposure of the contents of the internal auditory canal and positive facial nerve identification. Because access to the posterior fossa is limited, the middle fossa approach is most appropriate for tumors with less than 5 mm extension into the cerebellopontine angle. With the introduction of gadolinium-enhanced magnetic resonance imaging, very small acoustic tumors are diagonosed more frequently, and the middle fossa approach is well-suited for the removal of these tumors.

Intraoperative monitoring of facial and cochlear nerves during acoustic neuroma surgery. 1992.

Preservation of facial nerve function during acoustic neuroma surgery can be improved significantly by monitoring of facial electromyography (EMG) during surgery. Mechanical trauma during dissection causes EMG activity that can be played over a loudspeaker for direct feedback to the surgeon. Electrical stimulation can be used to locate the nerve even when it is out of direct view, and the threshold for stimulation provides a measure of facial (or other motor nerve) integrity. Cochlear nerve function also can be monitored by the recording of auditory brain stem responses or compound action potentials from an electrode placed on the nerve at the brain stem root entry zone.

Surgical approaches and complications in the removal of vestibular schwannomas. 2007.

Vestibular schwannomas are benign tumors that usually originate from the balance portion of cranial nerve VIII. The treatment options currently available for vestibular schwannomas include observation with serial imaging, stereotactic radiation, and microsurgical removal. Although the ultimate goal in treatment of vestibular schwannomas is preservation of life, the best option for each patient depends on symptoms, tumor size, tumor location, and the patient's general health and age. Surgical exposure of the cerebellopontine angle for removal of vestibular schwannomas can be performed safely via a translabyrinthine, retrosigmoid, and middle fossa approach. Each approach has its advantages and disadvantages. The goal of surgery is complete eradication of tumor with preservation of hearing and facial nerve function when possible.

LINAC radiosurgery and radiotherapy treatment of acoustic neuromas. 2007.

This article provides an introduction to radiation therapy as it applies to intracranial tumors. It also provides a review of the natural growth progression of acoustic neuromas and accuracy of tumor size determination. Literature on the use of linear accelerator stereotactic radiosurgery and fractionated radiotherapy in acoustic neuroma management is reviewed and summarized. Specifically, the rates of reported tumor control, hearing preservation, facial and trigeminal nerve complications, and hydrocephalus are analyzed. Although the complication rates associated with linear accelerator therapy are relatively low, hearing preservation is poor and acoustic neuroma control is variable.