We have developed a technique for craniotomy, which facilitates awake neurological testing, is safe, and has good patient satisfaction.

Neuroanaesthesia continues to develop and expand. It is a speciality where the knowledge and expertise of the anaesthetist can directly influence patient outcome. 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, minimizing interference 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 has always 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 current controversies in elective neurosurgical practice, future perspectives, and the place of awake craniotomies in the armamentarium of the neuroanaesthetist.

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SummaryThe effects of increasing degrees of flexion on cerebrospinal fluid pressure were investigated in 12 neurosurgical patients requiring lumbar subarachnoid drains. Cerebrospinal fluid pressure and central venous pressure were measured in three positions: fully flexed ('chin on chest'), flexed at ninety degrees and straight. There was a significant increase in cerebrospinal fluid pressure on moving from the fully flexed to the flexed position (p < 0.0001), but not from the flexed to the straight position. These results were mirrored by smaller changes in central venous pressure. In patients without intracranial pathology these increases in cerebrospinal fluid pressure are probably unimportant. However, intracranial pathology may result in low cerebral perfusion pressures and any increase in cerebrospinal fluid pressure in this group may be harmful. The fully flexed position should be avoided when inserting lumbar drains in at risk patients. Lumbar subarachnoid drains are often used to improve surgical exposure during certain neurosurgical procedures, for example intracranial aneurysm surgery. These drains are commonly inserted with the patient in the flexed, lateral position. To help with placement, patients are often fully flexed, i.e. curled up with full flexion of the thoracolumbar spine and with both the hips and neck fully flexed. Changes in patient position are known to have marked effects on the intracranial environment [1]. Flexion of the thoracolumbar spine has been shown to cause a rise in cerebrospinal fluid pressure (pCSF) and, in patients with an intact craniospinal axis, pCSF should reflect intracranial pressure (ICP). Even small increases in pCSF may prove deleterious in patients who have raised ICP or impaired cerebral perfusion. The aim of this study was to determine any changes in pCSF in relation to differing degrees of flexion. MethodsTwelve neurosurgical patients, in whom lumbar drains were required, were studied. All patients gave informed consent and the study had the approval of the local medical ethics committee. The patients were premedicated with glycopyrrolate intramuscularly and anaesthesia was induced with thiopentone and fentanyl. Vecuronium was given to facilitate tracheal intubation and the lungs were hyperventilated with isoflurane in N 2 O and O 2 to achieve a P E 0 CO 2 of 4 kPa. The patient was positioned in the left lateral position and a lumbar drain catheter was sited at the second lumbar interspace through an 18G Touhy needle. A midline approach was used in all cases and special attention was taken to avoid undue loss of CSF. On demonstration of free flow of CSF, the catheter was connected, via tubing filled with heparin-free saline, to a pressure transducer. The system was calibrated from 0-40 mmHg and pressure values were displayed on a chart recorder (TOA EPR-152A Electronic Polyrecorder). With the patient still in the left lateral position, measurements of pCSF were made for short periods: fully flexed, with full flexion of the thoracolumbar spine and both the hip...