Anestesiologia

British Journal of Anaesthesia 99 (1): 68–74 (2007)

doi:10.1093/bja/aem132

Anaesthesia for elective neurosurgery
J. Dinsmore*
Department of Anaesthesia, St George’s Hospital, London SW17 0RE, UK
*E-mail: judith.dinsmore@stgeorges.nhs.uk
Neuroanaesthesia continues to develop and expand. It is a speciality where the knowledge and expertise of the anaesthetist can directly influence patientoutcome. Evolution of neurosurgical practice is accompanied by new challenges for the anaesthetist. Increasingly, we must think not only as an anaesthetist but also as a neurosurgeon and neurologist. With the focus on functional and minimally invasive procedures, there is an increased emphasis on the provision of optimal operative conditions, preservation of neurocognitive function, minimizinginterference with electrophysiological monitoring, and a rapid, high-quality recovery. Small craniotomies, intraoperative imaging, stereotactic interventions, and endoscopic procedures increase surgical precision and minimize trauma to normal tissues. The result should be quicker recovery, minimal perioperative morbidity, and reduced hospital stay. One of the peculiarities of neuroanaesthesia hasalways been that as much importance is attached to wakening the patient as sending them to sleep. With the increasing popularity of awake craniotomies, there is even more emphasis on this skill. However, despite high-quality anaesthetic research and advances in drugs and monitoring modalities, many controversies remain regarding best clinical practice. This review will discuss some of the currentcontroversies in elective neurosurgical practice, future perspectives, and the place of awake craniotomies in the armamentarium of the neuroanaesthetist. Br J Anaesth 2007; 99: 68–74 Keywords: anaesthesia, neurosurgical; complications; safety, techniques; surgery, awake craniotomy

Neuroanaesthesia continues to develop and expand. It is a speciality where the knowledge and expertise of theanaesthetist may directly influence patient outcome. Evolution of neurosurgical practice is accompanied by new challenges for the anaesthetist with greater focus on functional and minimally invasive procedures. The emphasis remains on the provision of good operative conditions, assessment and preservation of neurological function, and a rapid, high-quality recovery.

Basic principles
The basicprinciples of neuroanaesthesia remain unchanged— the provision of optimal operative conditions, maintenance of cerebral perfusion pressure (CPP), and cerebral oxygenation. However, despite advances in drugs and monitoring modalities, neuroanaesthesia is steeped in tradition and many controversies remain regarding best clinical practice.

Drugs
Despite theoretical benefits of i.v. agents, volatile agentsremain popular. Numerous studies have described their differential effects on cerebral haemodynamics and

intracranial pressure (ICP). In a study comparing desflurane, isoflurane, and sevoflurane in a porcine model of intracranial hypertension, at equipotent doses and normocapnia, cerebral blood flow (CBF) and ICP were greatest with desflurane and least with sevoflurane.26 The authors went on toconfirm these findings in clinical studies, demonstrating that sevoflurane caused the least vasodilatation.27 In two different studies in healthy patients, isoflurane was found to impair autoregulation, although this was reversible with hyperventilation, while autoregulation was virtually intact with sevoflurane 1 – 1.2% at normocapnia.44 52 Although further large-scale studies are needed, sevoflurane appearsto be the most suitable volatile agent for neuroanaesthesia. Propofol has many theoretical advantages by reducing cerebral blood volume (CBV) and ICP and preserving both autoregulation and vascular reactivity. In healthy subjects, propofol reduced CBF, as measured by positron emission tomography (PET), more than sevoflurane at equipotent concentrations.41 The effects of desflurane, isoflurane at...