Long-term reliability of the telemetric Neurovent-P-tel sensor: in vivo case report.

Intracranial pressure (ICP) measurements are imperative for the proper diagnosis and treatment of several neurological disorders. Telemetric sensors have shown their utility for ICP estimation in short-term monitoring in humans. However, their long-term reliability is uncertain. The authors present the case of a 37-year-old woman diagnosed with benign intracranial hypertension and obesity. The patient underwent gastric bypass surgery for ICP control. In order to monitor ICP before and after bariatric surgery, a Neurovent-P-tel sensor was implanted in the left frontal lobe. After gastric bypass, normal ICP values were recorded, and the patient's visual fields improved. However, the patient experienced incapacitating daily headaches. The authors decided to implant a Codman Microsensor ICP transducer in the right frontal lobe to assess the long-term reliability of the Neurovent-P-tel measurements. A comparison of the recordings at 24 and 48 hours showed good correlation and reliability during long-term monitoring with the Neurovent-P-tel, with minimal zero drift after 11 months of implantation.

Current clinical practice in postoperative endovascular aneurysm repair imaging surveillance.

PURPOSE: To investigate the current clinical practice in postoperative endovascular aneurysm repair (EVAR) imaging surveillance. MATERIALS AND METHODS: Corresponding authors of EVAR publications during the years 2006-2011 and subscribers to an endovascular journal were invited to complete a 27-question online survey related to institutional demographics, standard post-EVAR imaging surveillance, and imaging protocols in special circumstances (eg, renal insufficiency). RESULTS: The survey was completed by 515 of 9,631 physicians performing EVAR from 52 countries. Of respondents, 65.3% were affiliated with experienced centers where EVAR has been performed for > 10 years or with > 50 EVAR procedures performed per year. Computed tomography (CT) angiography was the modality used most often for standard surveillance with a maximum time interval between studies of 12 months in 78.8% of centers out to 5 years. Experienced centers were more likely to delay follow-up imaging to 1 year after an unremarkable initial post-EVAR imaging study (P < .001), to extend surveillance intervals > 12 months (P = .043), and to use ultrasound (P < .01) for surveillance. After the detection of a type II endoleak, CT angiography was favored for follow-up by 59.4% of the respondents. Experienced centers were more likely to favor ultrasound (P = .006) and to schedule this follow-up examination later (after 6-12 months, P < .001). Of respondents, 62.8% used a glomerular filtration rate threshold of < 30 mL/min for not performing contrast-enhanced CT scan. In patients with renal insufficiency, most respondents performed ultrasound with or without a concomitant noncontrast CT scan. CONCLUSIONS: CT is the most frequently used method of long-term surveillance after EVAR. Use of ultrasound for long-term surveillance, extension of follow-up time intervals, or both were most often reported in experienced centers.

Recent advances in sensing oropharyngeal swallowing function in Japan.

Dysphagia (difficulty in swallowing) is an important issue in the elderly because it causes aspiration pneumonia, which is the second largest cause of death in this group. It also causes decline in activities of daily living and quality of life. The oral phase of swallowing has been neglected, despite its importance in the evaluation of dysphagia, because adequate protocols and measuring devices are unavailable. However, recent advances in sensor technology have enabled straightforward, non-invasive measurement of the movement of important swallowing-related organs such as the lips and tongue, as well as the larynx. In this article, we report the present state and possibility of clinical application of such systems developed in Japan.

Biomechanical evaluation of segmental instability in degenerative lumbar spondylolisthesis.

Here we investigated the biomechanical properties of spinal segments in patients with degenerative lumbar spondylolisthesis (DLS) using a novel intraoperative measurement system. The measurement system comprised spinous process holders, a motion generator, a load cell, an optical displacement transducer, and a computer. Cyclic displacement of the holders produced flexion-extension of the segment with all ligamentous structures intact. Stiffness, absorption energy (AE), and neutral zone (NZ) were determined from the load-deformation data. Forty-one patients with DLS (M/F = 15/26, mean age 68.6 years; Group D) were studied. Adjacent segments with normal discs in six patients (M/F = 3/3, mean age 35 years) were included as a control group (Group N). Flexion stiffness was significantly lower in Group D than in Group N. The NZ, however, was significantly greater in Group D than in Group N. Thus, compared to normal segments, spinal segments with DLS had a lower flexion stiffness and a higher NZ. NZs in Group D were, however, widely distributed compared to those in Group N that showed NZ <2 mm/N in all cases, suggesting that the segment with DLS is not always unstable and that the segments with NZ >2 mm/N can be considered as unstable.

A portable tactile sensory diagnostic device.

Current methods for applying multi-site vibratory stimuli to the skin typically involve the use of two separate vibrotactile stimulators, which can lead to difficulty with positioning of stimuli and in ensuring that stimuli are delivered perfectly in phase at the same amplitude and frequency. Previously, we reported a two-point stimulator (TPS) that was developed in order to solve the problem of delivering two-point stimuli to the skin at variable distances between the sites of stimulation. Because of the success of the TPS, we designed and fabricated a new stimulator with four significant improvements over our original device. First, the device is portable, lightweight and can be used in a variety of non-laboratory settings. Second, the device consists of two independently controlled stimulators which allow delivery of stimuli simultaneously to two distinct skin sites with different amplitude, frequency and/or phase. Third, the device automatically detects the skin surface and thus allows for much better automated control of stimulus delivery. Fourth, the device is designed for rapid manufacture and, therefore, can be made readily available to other research (non-laboratory) settings. To demonstrate the device, a modified Bekesy tracking method was used to evaluate the simultaneous amplitude discrimination capacity of 20 subjects.

Validation of a mechanical apparatus for the measurement of avian walking.

Recent research has demonstrated that avian species may show an enhanced locomotor response to repeated drug exposure, a phenomenon called sensitization. Further research in this domain is warranted as such results not only establish the generality of previous findings, but may lend to a better understanding of sensitization in general. At present, there are no well-studied measurement devices for automating the measurement of bird movement. The present research evaluated a mechanical device comprised of moveable floor panels to assess its suitability. Evaluations of the device were made over the course of repeated cocaine administration. The results showed that there was high correspondence between the apparatus' responses and human observers' responses to movement by pigeons. The apparatus, furthermore, provided useful data on spatial orientation that revealed individual differences in the response to cocaine beyond those available from a collapsed measure of overall output. In sum, this recording strategy appears a viable instrument for the measurement of avian locomotion.

Intradiscal pressure measurements in normal discs, compressed discs and compressed discs treated with axial posterior disc distraction: an experimental study on the rabbit lumbar spine model.

Intervertebral disc (IVD) pressure measurement is an appropriate method for characterizing spinal loading conditions. However, there is no human or animal model that provides sufficient IVD pressure data. The aim of our study was to establish physiological pressure values in the rabbit lumbar spine and to determine whether temporary external disc compression and distraction were associated with pressure changes. Measurements were done using a microstructure-based fibreoptic sensor. Data were collected in five control rabbits (N, measurement lying prone at segment L3/4 at day 28), five rabbits with 28 days of axial compression (C, measurement at day 28) and three rabbits with 28 days of axial compression and following 28 days of axial distraction (D, measurement at day 56). Disc compression and distraction was verified by disc height in lateral radiographs. The controls (N) showed a level-related range between 0.25 MPa-0.45 MPa. The IVD pressure was highest at level L3/4 (0.42 MPa; range 0.38-0.45) with a decrease in both cranial and caudal adjacent segments. The result for C was a significant decrease in IVD pressure (0.31 MPa) when compared with controls (P=0.009). D showed slightly higher median IVD pressure (0.32 MPa) compared to C, but significantly lower levels when compared with N (P=0.037). Our results indicate a high range of physiological IVD pressure at different levels of the lumbar rabbit spine. Temporary disc compression reduces pressure when compared with controls. These data support the hypothesis that temporary external compression leads to moderate disc degeneration as a result of degradation of water-binding disc matrix or affected active pumping mechanisms of nutrients into the disc. A stabilization of IVD pressure in discs treated with temporary distraction was observed.

The Camino intracranial pressure device in clinical practice. Assessment in a 1000 cases.

BACKGROUND: Intracranial pressure (ICP) monitoring has become standard in the management of neurocritical patients. A variety of monitoring techniques and devices are available, each offering advantages and disadvantages. Analysis of large populations has never been performed. PATIENTS AND METHODS: A prospective study was designed to evaluate the Camino fiberoptic intraparenchymal cerebral pressure monitor for complications and accuracy. RESULTS: Between 1992-2004 one thousand consecutive patients had a fiberoptic ICP monitor placed. The most frequent indication for monitoring was severe head injury (697 cases). The average duration of ICP monitoring was 184.6 +/- 94.3 hours; the range was 16-581 hours. Zero drift (range, -17 to 21 mm Hg; mean 7.3 +/- 5.1) was recorded after the devices were removed from 624 patients. Mechanical complications such as: breakage of the optical fiber (n = 17); dislocations of the fixation screw (n = 15) or the probe (n = 13); and failure of ICP recording for unknown reasons (n = 4) were found in 49 Camino devices. CONCLUSIONS: The Camino ICP sensor remains one of the most popular ICP monitoring devices for use in critical neurosurgical patients. The system offers reliable ICP measurements in an acceptable percentage of device complications and the advantage of in vivo recalibration. The incidence of technical complications was low and similar to others devices.

Bite force measurement in awake rats.

This report describes the implementation of bite force measurement in awake rats and software instruments (Spike 2 script programs) that quantify and analyze the bite force data. One script program employs user-defined control of threshold bite force, which allows an easy adjustment of target force prior to training the rat. Furthermore, the interactive program allows on-line control of threshold bite force at anytime during the training session. Upon detection of the bite force crossing the threshold, it automatically triggers the external water delivery system for reinforcement. Another script program detects successful biting attempts, compiles times stamps and force level for each attempted bite, and calculates the total number of bites, success rate and mean bite force per training session. Using the new methodology, we trained five adult rats to produce the bite force of 1300 g. Our results demonstrated that all rats achieved the target force with a similar time course and exhibited little variability in success rate and mean bite force. The script programs provided instant review and analyses of the captured data. These techniques simplify assessment of bite force in behaving rats.

Transducers for foot pressure measurement: survey of recent developments.

Recent advances in the development of transducers for the measurement of vertical and shear forces acting on the plantar surface of the foot are reviewed. Barefoot and in-shoe discrete and matrix transducers are reviewed in terms of structure, operation, performance and limitations. Examples of capacitive, piezo-electric, optical, conductive and resistive types of transducer are presented. Where available, the current clinical status is specified.