Transcranial Doppler-derived indices of cerebrovascular haemodynamics are independent of depth and angle of insonation.

Continuous measurement of cerebral blood flow velocity (CBFV) of the middle cerebral artery (MCA) using transcranial Doppler (TCD) and arterial blood pressure (ABP) monitoring enables assessment of cerebrovascular haemodynamics. Further indices describing cerebrovascular function can be calculated from ABP and CBFV, such as the mean index (Mxa) of cerebrovascular autoregulation, the 'time constant of the cerebral arterial bed' (tau), the 'critical closing pressure' (CrCP) and a 'non-invasive estimator of ICP' (nICP). However, TCD is operator-dependent and changes in angle and depth of MCA insonation result in different readings of CBFV. The effect of differing CBFV readings on the calculated secondary indices remains unknown. The aim of this study was to investigate variation in angle and depth of MCA insonation on these secondary indices. In eight patients continuous ABP and ipsilateral CBFV monitoring was performed using two different TCD probes, resulting in four simultaneous CBFV readings at different angles and depths per patient. From all individual recordings, the K-means clustering algorithm was applied to the four simultaneous longitudinal measurements. The average ratios of the between-clusters, sum-of-squares and total sum-of-squares were significantly higher for CBFV than for the indices Mxa, tau and CrCP (p < 0.001, p = 0.007 and p = 0.016) but not for nICP (p = 0.175). The results indicate that Mxa, tau and CrCP seemed to be not affected by depth and angle of TCD insonation, whereas nICP was.

Outcomes following grade V subarachnoid haemorrhage: A single-centre retrospective study.

SummaryGrade V subarachnoid haemorrhage is associated with high mortality and morbidity, yet there are few contemporary reports on the treatment provided and outcomes of these patients. In this single-centre retrospective cohort study, we primarily sought to determine the 12-month mortality of patients admitted to the Royal Adelaide Hospital intensive care unit between 2006 and 2016 with grade V subarachnoid haemorrhage. Secondary objectives were to describe treatments provided, patient destination following hospital discharge, organ donation and hospital financial costs. Over the 11-year study period, there were 139 patients admitted with grade V subarachnoid haemorrhage. The annual number of admissions did not change over time. The median age was 56 (interquartile range 48-70) years, 88 (63%) were female and 77 (55%) had a procedure to isolate an aneurysm. There were 77 (55%) patients who died in the intensive care unit, 87 (63%) died in hospital and 89 (64%) had died at 12 months. Of the 52 patients who survived to hospital discharge, 33 (63%) were transferred to a rehabilitation facility, 17 (33%) to another acute care hospital and two (4%) were discharged. Of the 87 patients who died in hospital, 45 (52%) donated organs. The total hospital cost of managing this cohort was A$8.3 million, with a median cost of A$41,824 (interquartile range A$9,933-A$97,332) per patient. Grade V subarachnoid haemorrhage has a high mortality rate, with one-third of patients alive after one year.

Home telemonitoring of intracranial pressure.

BACKGROUND: As technical progress advances, telemonitoring has become an important part of patient care in many areas of medical treatment. However, distanced surveillance of intracranial pressure (ICP) could not be established so far. With the recent introduction of a telemetric ICP measurement probe, new possibilities arise. Here, we report on a new home setup enabling home telemonitoring of intracranial pressure. METHODS: Twenty patients suffering from disturbances of cerebrospinal fluid circulation, who underwent insertion of a telemetric ICP measurement probe, were provided with medical equipment to read ICP at home and save the data on an internet-enabled computer. Training in handling the equipment was performed during in-patient stay; recorded and uploaded ICP data was then analyzed online. Therefore, the treating medical team was able to access the ICP data via a secure internet connection while telephone conferencing with the patient. RESULTS: Almost 7400 h of ICP data were recorded at home and evaluated via an internet connection according to the telemonitoring setup. This corresponds to an average record time of about 370 h per patient. ICP profiles were observed following endoscopic treatment, shunting procedures, or valve adjustments. The mean distance between the patients' residence and the consulting hospital was 172 km (range, 16-649 km). CONCLUSIONS: ICP measurements have become accessible for telemonitoring purposes. This new management of hydrocephalus reflects an alternative method in patient care, especially for those who live far away from specialized centers.

Endoscopic-Assisted Burr Hole Reservoir and Ventricle Catheter Placement.

BACKGROUND: Accurate positioning of a ventricle catheter is of utmost importance. Various techniques to ensure optimal positioning have been described. Commonly, after catheter placement, additional manipulation is necessary to connect a burr hole reservoir or shunt components. This manipulation can lead to accidental catheter dislocation and should be avoided. Here, we present a new technique that allows direct endoscopic insertion of a burr hole reservoir with an already mounted ventricle catheter. METHODS: Before insertion, the ventricle catheter was slit at the tip, shortened to the correct length, and connected to the special burr hole reservoir. An intracatheter endoscope was then advanced through the reservoir and the connected catheter. This assemblage allowed using the endoscope as a stylet for shielded ventricular puncture. To confirm correct placement of the ventricle catheter, the endoscope was protruded a few millimeters beyond the catheter tip for inspection. RESULTS: The new technique was applied in 12 procedures. The modified burr hole reservoir was inserted for first-time ventriculoperitoneal shunting (n = 1), cerebrospinal fluid withdrawals and drug administration (n = 2), or different stenting procedures (n = 9). Optimal positioning of the catheter was achieved in 11 of 12 cases. No subcutaneous cerebrospinal fluid collection or fluid leakage through the wound occurred. No parenchymal damage or bleeding appeared. CONCLUSIONS: The use of the intracatheter endoscope combined with the modified burr hole reservoir provides a sufficient technique for accurate and safe placement. Connecting the ventricle catheter to the reservoir before the insertion reduces later manipulation and accidental dislocation of the catheter.

Telemetric Intracranial Pressure Monitoring with the Raumedic Neurovent P-tel.

BACKGROUND: Devices enabling long-term intracranial pressure monitoring have been demanded for some time. The first solutions using telemetry were proposed in 1967. Since then, many other wireless systems have followed but some technical restrictions have led to unacceptable measurement uncertainties. In 2009, a completely revised telemetric pressure device called Neurovent P-tel was introduced to the market. This report reviews technical aspects, handling, possibilities of data analysis, and the efficiency of the probe in clinical routine. METHODS: The telemetric device consists of 3 main parts: the passive implant, the active antenna, and the storage monitor. The implant with its parenchymal pressure transducer is inserted via a frontal burr hole. Pressure values can be registered with a frequency of 1 Hz or 5 Hz. Telemetrically gathered data can be viewed on the storage monitor or saved on a computer for detailed analyses. A total of 247 patients with suspected (n = 123) or known (n = 124) intracranial pressure disorders underwent insertion of the telemetric pressure probe. RESULTS: A detailed analysis of the long-term intracranial pressure profile including mean values, maximum and negative peaks, pathologic slow waves, and pulse pressure amplitudes is feasible using the detection rate of 5 Hz. This enables the verification of suspected diagnoses as normal-pressure hydrocephalus, benign intracranial hypertension, shunt malfunction, or shunt overdrainage. Long-term application also facilitates postoperative surveillance and supports valve adjustments of shunt-treated patients. CONCLUSIONS: The presented telemetric measurement system is a valuable and effective diagnostic tool in selected cases.

What neurosurgeons need to know about dabigatran etexilate (pradax(®)/pradaxa(®)/prazaxa(®)).

Dabigatran etexaliate is a novel oral anticoagulant that directly inhibits thrombin. It offers a number of substantial medical benefits over other oral and parenteral anticoagulants but its advent raises important neurosurgical considerations. Dabigatran has important potential benefits. Unlike warfarin, it does not require routine blood tests to monitor its anticoagulative effect and there is no need for dose titration. Drug interactions are greatly simplified when compared to warfarin as dabigatran is not metabolized by cytochrome p450 isoenzymes. As a result, dabigatran has been approved in many jurisdictions for DVT prophylaxis after orthopaedic surgery and also for the prevention of embolic events associated with non-valvular atrial fibrillation. There are, however, important neurosurgical challenges associated with regular dabigatran use. Unlike current anti-coagulants, there is no specific reversal agent for dabigatran. Known reversal options include activated charcoal (within one to two hours of intake) and renal dialysis. Protamine sulfate and vitamin K are unlikely to affect the activity of dabigatran. Platelet concentrates will not inactivate dabigatran's anti-thrombin properties. Assessing the degree of anticoagulation is difficult as conventional markers of serum coagulability are typically normal in patients taking dabigatran. The potential neurosurgical challenges of dabigatran were cast in sharp relief by a recent case report from the United States that is considered in this note. In the absence of a clear reversal pathway, we propose a treatment algorithm for chronic dabigatran use based on the replacement of any deficient factors and rapid access to renal dialysis.

Using smart phone video to supplement communication of radiology imaging in a neurosurgical unit: technical note.

BACKGROUND: The use of smart phones within medicine continues to grow at the same rate as mobile phone technology continues to evolve. One use of smart phones within medicine is in the transmission of radiological images to consultant neurosurgeons who are off-site in an emergency setting. In our unit, this has allowed quick, efficient, and safe communication between consultant neurosurgeon and trainees, aiding in rapid patient assessment and management in emergency situations. OBJECTIVE: To describe a new means of smart phone technology use in the neurosurgical setting, where the video application of smart phones allows transfer of a whole series of patient neuroimaging via multimedia messaging service to off-site consultant neurosurgeons. METHOD/TECHNIQUE: Using the video application of smart phones, a 30-second video of an entire series of patient neuroimaging was transmitted to consultant neurosurgeons. With this information, combined with a clinical history, accurate management decisions were made. RESULTS: This technique has been used on a number of emergency situations in our unit to date. Thus far, the imaging received by consultants has been a very useful adjunct to the clinical information provided by the on-site trainee, and has helped expedite management of patients. CONCLUSION: While the aim should always be for the specialist neurosurgeon to review the imaging in person, in emergency settings, this is not always possible, and we feel that this technique of smart phone video is a very useful means for rapid communication with neurosurgeons.

Glioma extent of resection and ultra-low-field iMRI: interim analysis of a prospective randomized trial.

Aiming at providing high-class evidence regarding the use of intraoperative MRI (ioMRI), we are conducting a prospective randomized controlled trial. Adult patients with contrast enhancing lesions suspicious of malignant gliomas scheduled to undergo radiologically complete tumor resection are eligible to enter this trial. After giving their informed consent, patients are randomized to undergo either ioMRI-guided or conventional microneurosurgical tumor resection. To assess the extent of resection, pre- and early postoperative high-field MR images are obtained to perform volumetric analyses. Primary endpoint of the study is the rate of radiologically complete tumor resections. After the inclusion of 35 patients, we performed an interim analysis. In six patients, histopathological examination revealed metastases, so they were excluded from further analyses. Thus, data from 29 patients with gliomas could be analyzed. There were no significant differences in patient age (P=0.28) or preoperative tumor sizes (P=0.40) between the two treatment groups. We observed a trend towards a higher rate of complete tumor resections in the ioMRI-group compared to the control group (P=0.07). Postoperative tumor volumes were significantly lower in the ioMRI-group than in the control group (P<0.05). The use of ioMRI appears to be associated with a higher rate of radiographically complete as well as near total tumor resections compared to conventional microneurosurgery.