No abstract

The potential for serious complications after venous air embolism and successful malpractice liability claims are the principle reasons for the dramatic decline in the use of the sitting position in neurosurgical practice. Although there have been several studies substantiating the relative safety compared with the prone or park bench positions, its use will continue to decline as neurosurgeons abandon its application and trainees in neurosurgery are not exposed to its relative merits. How can individual surgeons continue to use this position? Will individual, difficult surgical access cases be denied the obvious technical advantages of the sitting position? Limited use of the sitting position should remain in the neurosurgeon's armamentarium. However, several caveats must be emphasized. Assessment of the relative risk-benefit, based on the individual patient's physical status and surgical implications for the particular intracranial pathology, is of paramount importance. The patient should be informed of the specific risks of venous air embolism, quadriparesis and peripheral nerve palsies. Appropriate charting of patient information provided and special consent issues are essential. An anaesthetic input into the decision to use the sitting position is a sine qua non. The presence of a patient foramen ovale is an absolute contraindication. Preoperative contrast echocardiography should be used as a screening technique to detect the population at risk of paradoxical air embolism caused by the presence of a patent foramen ovale. The technique involves i.v. injection of saline agitated with air and a Valsalva manoeuvre is applied and released. Use of this position necessitates supplementary monitoring to promptly detect and treat venous air embolism. Doppler ultrasonography is the most sensitive of the generally available monitors to detect intracardiac air. The use of a central venous catheter is recommended, with the tip positioned close to the superior vena cava junction with the right atrium, to aspirate intravascular gas. Measures to minimize hypotension associated with the sitting position include a slow, staged positioning over 5-10 min and use of the 'G suit' inflated with compressed air applied to the lower extremities and pelvis. Use of the sitting or upright position for patients undergoing posterior fossa and cervical spine surgery presents unique challenges for the anaesthetist. With appropriate patient selection and preparation, and using prudent intraoperative monitoring and anaesthetic techniques, selected patients should still benefit from the optimum access to mid-line lesions, improved cerebral venous decompression, lower intracranial pressure and enhanced gravity drainage of blood and CSF associated with the sitting position.

This is a report of an hydrocephalic adult, in whom a unishunt system migrated upwards into the ventricle despite using the appropriate clips (lock and slip). The shunt migration discovered 3 months following its insertion. Several mechanisms contributed to the migration; negative sucking intra-ventricular pressure, positive pushing intra-abdominal pressure, tortuous subcutaneous track and neck movements. It seams that lock and slip clips are not enough fixation. The best way of preventing such shunt migration is interposing a reservoir between the ventricular and peritoneal catheters.

Primary intracranial plasma cell granuloma (PCG) is a rare form of inflammatory pseudotumour often characterized by non-neoplastic proliferation of plasma cells. The following case indicates a potential role for steroid therapy after subtotal resection.