Continuous recording of middle cerebral artery blood velocity in clinical neurosurgery

Summary Intracranial pressure, arterial blood pressure, and middle cerebral artery blood velocity were monitored for periods from 1 to 10 days in 30 neurosurgical intensive care patients. The recordings revealed rapid changes in the cerebral perfusion and gave insight into individual cerebral haemodynamic states.Twenty patients consistently showed CO₂ reactivity within normal limits, between 2.5 and 5% per mm Hg (19–38% per kPa). Severely impaired CO₂ reactivity, considerably below 1% per mm Hg (7.5% per kPa) was observed in four patients. Three of these patients died, while the fourth patient survived in a persistent vegetative state.Seven patients demonstrated pressure-passive blood velocity changes throughout the observed CPP range. The four patients with severely impaired CO₂ reactivity all belonged to this group. The recordings from three of the remaining 23 patients showed signs of MCA blood velocity autoregulation with a lower regulatory limit of about 40–45 mm Hg. This observation is in keeping with findings from electromagnetic flowmetry on brain arteries in the neurosurgical operating field, and supports blood velocity measurements as a relevant index of brain perfusion in clinical neurosurgery and neuro-intensive care settings.     

Digital photography using the intraoperative microscope in neurosurgery

Background

The ability to obtain high-resolution intraoperative microscopic images has previously been reserved for those with expensive microscope-mounted cameras, standard optical or digital. The authors review the technique and utility of intraoperative digital photography through the microscope.

Methods

We present a simple technique for obtaining high-quality digital micrographs without the need for special equipment that may be expensive, complex, and/or dedicated to a specific operative microscope.

Results

Images and video may be obtained using a standard personal digital camera.

Conclusions

Use of the technique presented provides the surgeon with the ability to acquire high-quality intraoperative microphotographs and video.     

Digital recording in microsurgery. Technical note

The authors examine the quality of intraoperative photography in which digital recording technology, including a microdigital camera and digital video paired with an operating microscope, is used during neurosurgery. A microdigital camera developed for this purpose (1.4 million pixels) was attached to an operating microscope and used during surgery. The same surgical views with precisely the same optical conditions were taken through the microscope by using both a conventional 35-mm camera and the microdigital camera, and the quality of the final output was compared. In addition, the quality of the digital camera photographs was compared with the still photograph clipped from the digital video recording. The quality of the photographs taken with a microdigital camera was superior to the quality of those obtained with the conventional 35-mm camera. The success rate of recording (what you see is what you get) was almost 100%. The quality of the still photographs clipped from the digital video was nearly equal to those taken with the digital camera. The microdigital camera system is superior to the conventional 35-mm camera in neurosurgery in terms of its success rate and the quality of the photography. It is also a space-saving system for storing the huge amount of data generated in the recording of surgical procedures, and the cost/performance ratio is superior to that of the conventional method. Digital technology including digital cameras and videos is very useful for clear recording of microsurgical procedures.     

Digital video recording of cardiac surgical procedures

PURPOSE: We attempted to find a method of reducing time and effort for recording videos of cardiac surgical procedures. DESCRIPTION: A camera mounting arm designed by us provided a properly fixed digital camera location for undisturbed recording. The camera and its remote control unit provided an opportunity for the surgeon to record only the steps of the operation without need for editing. EVALUATION: Digital videos produced by this method required no additional time from the surgeon except to record the commentary at leisure. The video recorded was of excellent quality and provided a well-focused recording of the steps of the operation. CONCLUSIONS: The technique described for video recording of cardiac surgical procedures provides a time-saving and easy method for good reproduction of surgical procedures.     

Staged functional neurosurgery using image fusion: electronic atlas and microelectrode recording at Dundee

The unforgiving nature of the thalamus, the globus pallidus and the subthalamic nucleus necessitates precise localization of functional targets. This requires the total attention of both the patient and the surgeon. To maximize the concentration of the patient and provide the most accurate localization, we performed staged stereotactic functional procedures. The first stage was performed under general anesthesia to abolish any head movement. We fused CT and MRI images and correlated the fused images with a digitized Talairach brain atlas. We calculated the target coordinates and fixed a modified Bennett Sphere to the skull with the central hole defining the trajectory to the target. The surrounding 12 holes gave parallel trajectories to targets surrounding the anatomical target at 2-mm intervals. The second stage was performed at least a week later under local anesthesia. Microelectrode recording using three simultaneous channels was used to refine the target. Once the microelectrode recordings and macrostimulation confirmed the desired target, a lesion was created or an Activa neurostimulator was inserted. Our early results using this technique in 28 procedures (in 19 patients) indicate a good outcome in 86% and a technical failure in 1 patient.