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PubMed2004

Measuring hand intrinsic muscle strength: normal values and interrater reliability.

BACKGROUND: The intrinsic muscles of the hand are of interest in spinal cord injury (SCI) and other myelopathies, because they are innervated by the most caudal cord segments innervating the upper limb. In addition, abnormalities of the peripheral nervous system, such as peripheral nerve entrapments, often affect hand intrinsic muscle strength of SCI patients. Therefore, measuring hand intrinsic strength may allow for early diagnosis of neurologic decline. METHODS: A method was developed for measuring strength of hand intrinsic muscles with a handheld myometer. With the use of a handheld myometer, this study examined the distribution of strength measurements for second-digit abductors, fifth-digit abductors, and thumb opposers in able-bodied participants and in individuals with weakness. The quantitative measurements were compared with manual muscle test scores and interrater reliability is described for these hand intrinsic strength measurements. Thirty-one able-bodied individuals participated (17 men, 14 women; mean age = 37.7 years). In addition, 24, patients with SCI participated (23 men, 1 woman; mean age = 53.5 years; 9 with paraplegia and 14 with tetraplegia as a primary diagnosis). The Bland-Altman method was used to test for interrater reliability. RESULTS: Mean strength of able-bodied participants was 5.0 kg for second-digit abduction, 3.1 kg for fifth-digit abduction, and 5.0 kg for thumb opposition, and the lower limits of normal were 3.0, 1.8, and 3.4 kg, respectively. The 95th percentile of interrater differences were 29.3% for second-digit abduction, 38.5% for fifth-digit abduction, and 43.7% for thumb opposition. CONCLUSION: Abnormal hand intrinsic strength should be suspected if values are lower than the 5th percentile values listed above or if strength change exceeds the 95th percentile for interrater differences shown above. These quantitative hand strength measurements may allow for earlier diagnosis of secondary neurologic complications and may aid in monitoring neurologic recovery in persons with SCI.

Adult↗
PubMed2006

Arthroscopic evaluation of cartilage degeneration using indentation testing--influence of indenter geometry.

BACKGROUND: It has been suggested that the early onset of cartilage degeneration might be detected with a handheld indentation probe during knee arthroscopy, prior to any visible change on the articular surface. Collagen degradation has been considered as the first sign of cartilage degeneration. Therefore, it is important to consider the collagen network as a distinct constituent in the study of arthroscopic evaluation of cartilage degeneration. METHODS: The tip of an arthroscopic probe (indenter) was modeled as rigid and in contact with a cartilage/bone disk of sufficiently large radius to simulate an indentation in a joint. A fibril-reinforced model of cartilage, including streaming potentials and distinct constitutive laws for the proteoglycan matrix and collagen network, was used to determine the contact mechanics of indenter and cartilage. The finite element package ABAQUS was employed to obtain numerical solutions. FINDINGS: A spherical indenter produces a relatively uniform deformation in cartilage, but can easily slide on the articular surface. In contrast, a cylindrical indenter produces great deformation gradients for quick compression rates, but does not slide as easily on the articular surface as the spherical indenter. Small porous and large solid indenters should be used to evaluate the properties of the proteoglycan matrix and collagen network, respectively, in order to minimize or maximize the fluid pressure in the corresponding case. When the collagen network is substantially degraded, the gradients of fluid pressure and deformation are greatly reduced regardless of indenter geometry. INTERPRETATION: The indenter geometry including its porosity is important to the material safety of articular cartilage in indentation and precise evaluation of cartilage degeneration.

Arthroscopy↗
PubMed2005

Maintaining rotational equilibrium during object manipulation: linear behavior of a highly non-linear system.

We address issues of simultaneous control of the grasping force and the total moment of forces applied to a handheld object during its manipulation. Six young healthy male subjects grasped an instrumented handle and performed its cyclic motion in the vertical direction. The handle allowed for setting different clockwise (negative) or counterclockwise torques. Three movement frequencies: 1, 1.5 and 2 Hz, and five different torques: -1/3, -1/6, 0, 1/6 and 1/3 Nm, were used. The rotational equilibrium was maintained by two means: (1) Concerted changes of the moments produced by the normal and tangential forces, specifically anti-phase changes of the moments during the tasks with zero external torque and in-phase changes during the non-zero-torque tasks, and (2) Redistribution of the normal forces among individual fingers such that the agonist fingers--the fingers that resist external torque--increased the force in phase with the acceleration, while the forces of the antagonist fingers--those that assist the external torque--especially, the fingers with the large moment arms, the index and little fingers, stayed unchanged. The observed effects agree with the principle of superposition--according to which some complex actions, for example, prehension, can be decomposed into elemental actions controlled independently--and the mechanical advantage hypothesis according to which in moment production the fingers are activated in proportion to their moment arms with respect to the axis of rotation. We would like to emphasize the linearity of the observed relations, which was not prescribed by the task mechanics and seems to be produced by specific neural control mechanisms.

Adult↗
PubMed2005

Design and evaluation of a handheld impedance plethysmograph for measuring heart rate variability.

Heart rate variability (HRV) analysis from 10s ECGs has been shown to be reliable. However, the short examination time warrants a user-friendly system that can be used for ad-hoc examinations without normal preparation, unlike ECG. A handheld device has been developed that can measure ultra-short HRV from impedance plethysmographic recordings of the pulse wave in distal superficial arteries. The prototype device was made user-friendly through a compact, pen-like design and the use of integrated metal electrodes that were especially designed for dry operation. The main signal processing was performed by a digital signal processor, where the discrete heart beats were detected using a correlation algorithm that could adapt to individual pulse wave shapes to account for biological variation. The novel device was evaluated in 20 mainly young volunteers, using 10 s time-correlated ECG recordings as the reference method. Agreement between the two methods in measuring heart rate and root mean square of successive differences in the heart beat interval (RMSSD) was analysed using correlation coefficients (Pearson's R2), mean differences with 95% confidence intervals and 95% limits of agreement, and Bland-Altman plots. The correlation between the two methods was R2 = 1.00 and R2 = 0.99 when heart rate and RMSSD were measured, respectively. The Bland-Altman plots showed suitable agreement between the novel device and standard 10 s ECGs, which was substantiated by 95% limits of agreement of the difference of +/- 0.1 beats min(-1) and approximately +/- 10 ms for heart rate and RMSSD, respectively. Therefore the evaluation showed no significant systematic error of the novel device compared with ECG.

Adult↗
PubMed1998

Optimized evaluation of a pulsed 2.09 microns holmium:YAG laser impact on the rat brain and 3 D-histomorphometry of the collateral damage.

Since more than 20 years CO2 and Nd:YAG lasers are established in the microsurgery of the nervous system. CO2 lasers can be used handheld, but may be focused on the target area by mirror optics and sideports of the operating microscope's micromanipulator. Nd:YAG lasers have the disadvantage of deep penetration into the brain and provocation of a large collateral damage. The need is for a fibre conducted solid system for surgery in delicate areas as for brain stem surgery. Fibre conduction of near infrared lasers allows better exposure of the target area compared to hollow wave guides or mirror equipment. Fibres can be tapered and modified according to the purpose. The holmium:YAG (Ho:YAG) laser has acquired interest by introducing the system into microsurgery of parenchymal tissue. They have not been proven yet sufficiently for neurosurgical tasks. The effort to minimalize the collateral tissue damage has to be maximalized in the surgery of nervous tissue and functional low redundant brain stem or spinal cord tissue. Volumetric data may be more precise in comparison to depth and width data of the laser lesion even when the different levels of the tissue interaction have to be analyzed for estimation of the real side effects in nervous tissue. We have used 50-800 ml delivered Ho:YAG single pulses in cortical areas of Sprague-Dawley rats and investigated the different lesion zones by volumetric data. The functional lesion zone was detected and measured by immunohistological staining of the heat shock protein HSP 72. For further reduction of the focus area, we have used tapered 400 to 200 microns fibres.

Animals↗
PubMed2002

Evaluation of a new handheld biosensor for point-of-care testing of whole blood beta-hydroxybutyrate concentration.

OBJECTIVES: To evaluate performance characteristics of the newly available handheld combined glucose and ketone meter for beta-hydroxybutyrate measurement. DESIGN: Laboratory method evaluation. MAIN OUTCOME MEASURES: Accuracy of beta-hydroxybutyrate measurement and effect of acetoacetate interference at clinically important beta-hydroxybutyrate levels. RESULTS: Deming regression analysis of beta-hydroxybutyrate measurements assessed by the ketone sensor and a laboratory enzymatic method revealed a coefficient of determination of 0.989 (P<0.001). Passing-Bablok regression analysis showed a linear relationship between the two methods, ie Y= -0.32+1.13X. The 95% confidence interval of the slope and y-intercept were: slope=1.13 (95% confidence interval, 1.04 to 1.22); intercept= -0.32 (95% confidence interval, -0.59 to -0.06). The Bland-Altman plot showed a small proportional bias between the two methods. The mean bias +/-2 standard deviations was between -0.53 and 0.67 mmol/L. Beta-hydroxybutyrate measurements made by the sensor were linear up to 6 mmol/L. Replicate analysis of two samples spiked with 3.6 mmol/L and 0.8 mmol/L of beta-hydroxybutyrate resulted in coefficients of variation of 3.3% and 13%, respectively. The presence of acetoacetate caused a negative interference in beta-hydroxybutyrate measurement. Beta-hydroxybutyrate recovery was 97.0% and 90.7% when the ketone body ratios were 6:1 and 3:1, respectively. CONCLUSION: The analytical performance of the sensor, when operated according to manufacturer's instructions, could meet the needs of point-of-care beta-hydroxybutyrate measurement. Additional clinical studies are needed to assess the benefits of introducing such an assay in a clinical setting.

3-Hydroxybutyric Acid↗
PubMed2005

Frameless free-hand maneuvering of a small-diameter rigid-rod neuroendoscope with a working channel used during high-resolution imaging. Technical note.

A newly designed small-diameter rigid-rod neuroendoscope was created to evaluate the applicability of free-hand maneuvering during high-resolution imaging. The neuroendoscope was designed as a light, handheld tool weighing 550 g. A 20-cm-long objective lens, 2 mm in diameter, is placed in the lower two thirds of the single-space lumen of an oval-shaped outer sheath, 16.5 mm long and 3.5 x 2.5 mm at maximum diameter. Included are microinstruments of 1.3-mm diameter for various neuroendoscopic procedures, including microscissors, biopsy forceps, grasping forceps, monopolar coagulator/cutting rod, and bipolar coagulator that can be introduced through the upper one third of the lumen. Because the endoscope is held steady in the surgeon's left hand, with the handle gripped at the base, quick back-and-forth movements can be made along the long axis, via a peel-away sheath inserted to the ventricle, shifting of the endoscope tip to the side of the objective target will be minimal. Given the instrument's unified configuration, the surgeon will never lose orientation during maneuvering. Using the farthest right of three inlet/outlet orifices, the short and handy semiflexible microinstruments can be guided and controlled by the surgeon's right hand. After experience in 66 cases in which various neuroendoscopic procedures yielded excellent operative outcomes (morbidity rate in complications related to the endoscopic procedure 0%; mortality rate 0%), the endoscope prototype was finalized in the ideal form for frameless maneuvering that uses a rigid-rod endoscope. The "gun-butt" holder for use with the operator's left hand provides stability and allows the endoscope to be handled with improved control. These new aspects of the neuroendoscope and surgical technique offer substantial improvement over the flexible-steerable fiberoptic endoscopes.

Equipment Design↗
PubMed2003

Feasibility and cost-effectiveness of sentinel lymph node radiolocalization in stage N0 head and neck cancer.

OBJECTIVES: To determine the feasibility of sentinal lymph node (SN) radiolocalization and to assess the cost-effectiveness of the SN navigation surgery strategy in patients with stage N0 squamous cell carcinoma (SCC) of the head and neck. Patients Eleven consecutive patients with stage N0 SCC of the head and neck. METHODS: Head and neck lymphoscintigraphy was performed 2 hours after the injection of technetium Tc 99m tin colloid or phytate. A handheld gamma probe was used to detect the SN before and directly after making a skin incision. Nodes were evaluated histopathologically for micrometastasis. To determine the expected cost savings, a decision tree sensitivity analysis was designed based on the 2 competing strategies: ipsilateral neck dissection vs SN navigation surgery. The costs referred to billed costs based on the Japanese national insurance reimbursement system. RESULTS: The sensitivity of SN navigation surgery in our series was 100% (11/11) on a patient-by-patient basis and 94% (17/18) on a node-by-node basis. Micrometastasis was found in 36% (4/11). Assuming the micrometastasis prevalence, sensitivity, and specificity of navigation surgery for detecting SN to be 30%, 90%, and 100%, respectively, the decision tree sensitivity analysis showed that introduction of SN navigation surgery in place of ipsilateral neck dissection would yield cost savings of $1218 (US) per stage N0 patient in Japan and avoid 7 surgical deaths per 1000 patients who are supposed to undergo neck dissection in the neck dissection strategy. Break-even point analysis for the SN navigation surgery strategy showed that the threshold value required more than 41 patients for the savings to begin to accrue. CONCLUSION: Our results indicate that SN navigation surgery using radiolocalization is feasible and cost-effective, based on decision tree sensitivity analysis, in patients with stage N0 SCC of the head and neck.

Adult↗
PubMed2001

Handheld digital equipment for weight composite distress paradigms: new considerations and for rapid documentation and intervention of rodent populations.

Animal care in the third millennium will require a melding of scientific and humane interests to achieve optimal care of genetically engineered mice and to expedite scientific and medical advances by using these mammals. Undoubtedly, rodent patients present certain difficulties for those who wish to assess their daily well-being and to contribute to efficient and successful scientific discovery. High-density housing, large experimental groups, and low-lux room lighting makes the application of large-animal care standards to rodents seem daunting to researchers and veterinary care programs. In addition, great variability in training and experience among those responsible for the direct application of humane care to rodents exists. Most of the direct animal care in small animal facilities occurs in decentralized locales by personnel who have completed obligatory but relatively minimal animal care training. Examples of personnel in this category include postdoctoral fellows, junior-level scientists, summer students, and assistant laboratory animal technologists. Some programs even use the husbandry staff to perform health checks of high-risk populations on a daily basis. For this reason, the extrapolation of performance-based intervention in rodent care is difficult to apply practically. Early efforts to enhance humane outcome in rodents have been published by scientists and veterinarians and are largely directed at singular endpoints, such as weight loss and declining temperatures, in specific models. Scientists often are reluctant to accept such standards because of concern about premature intervention or variability between scorers and to reservations regarding a lack of procedural likeness with their proposed study. This paper highlights a digital method for melding current advanced animal scoring standards using palm pilot user-friendly methods that account for composite weight scoring, behavioral or physiologic attributes, and interventions. Information is rapidly downloaded and results in quick storage of large rodent population monitoring. This minimizes interpretative variability between caregivers and greater standardization of procedures. These considerations facilitate the rapid diagnosis of outliers and make possible intervention that streamlines the delivery of humane care to large experimental populations.

Animal Technicians↗
PubMed2005

Intuitive intraoperative ultrasound guidance using the Sonic Flashlight: a novel ultrasound display system.

OBJECTIVE: The Sonic Flashlight (SF) is a new handheld ultrasound (US) display device being developed at our institution. It replaces the standard monitor on a conventional ultrasound (CUS) system with a miniature monitor and half-silvered mirror to reflect real-time US images into the body. With the SF, the imaged body part appears translucent, with the US image appearing to float below the surface of the anatomy, exactly where it is being scanned. The SF merges the patient, US image, instrument, and operator's hands into the same field of view, allowing the user to operate directly on the US image using normal hand-eye coordination. In contrast, CUS procedures result in displaced hand-eye coordination when the operator looks away from the patient to view the CUS monitor. Intraoperatively, the SF may make localizing and accessing tumors, foreign bodies, hematomas, vascular malformations, and ventricles easier and more accurate, especially for those without extensive CUS training. METHODS: In this cadaver study, the SF was used to visualize the brain and guide a needle into an implanted simulated tumor. The needle was inserted both in the US plane and outside of the US plane. INSTRUMENTATION: Sonic Flashlight fifth generation research prototype. CONCLUSION: The needle was easily and intuitively visualized and guided into the lesion, both within and outside of the US plane. By having the US image appear directly beneath the brain surface, the surgeon can easily and quickly guide the needle or surgical instrument to the lesion. The operator's eyes never have to leave the surgical field, as they do with CUS technology. The impact of this device on neurosurgical procedures could be significant. The ease of use, intuitive function, and small instrument size allow the surgeon to quickly localize lesions, confirm surgical positioning, and assess postoperative results.

Brain Neoplasms↗
PubMed2001

Automated measurement of radiographic hip joint-space width.

Radiographic joint-space narrowing (JSN) is the principle indicator of cartilage loss in osteoarthritis (OA). JSN is usually assessed qualitatively by visual inspection or in clinical research, is measured manually with a graduated handheld lens directly applied to the x-ray film, or from digitized radiographs by hand tracing the joint margins with a mouse. The minimum joint-space width (mJSW) and joint-space area (JSA) are recorded as the indices of OA progression in epidemiological studies and clinical drug trials. We present a computerized method that automatically finds the articular margins of the hip to improve determination of mJSW and JSA. The algorithm requires that three seed points are manually identified on the femoral head and uses three steps to process each digitized hip x-ray. First, a Hough transform finds the center and radius (R) of a circle that approximates the femoral head. Finding R indicates whether magnification differences must be corrected on repeat exams. Second, a gradient algorithm finds the edge of the femoral head and acetabulum. Third, the mid-line of the femoral neck is automatically found and used to define the joint portion (theta) that is assessed for narrowing. theta is fixed for follow-up exams of the same subject. The algorithm was evaluated in three ways to determine its performance characteristics. First, the inter-reader and intra-reader variability for mJSW and JSA associated with the selection of the seed points was found to be negligible (< 1%) compared to the variability associated with manual scoring with a lens or by tracing the joint margins with a mouse. Second, from duplicate hip x-rays of 19 subjects with OA, the Root Mean Square Standard Deviation and coefficient of variation for mJSW and JSA defined by the algorithm was determined to be better than manual techniques by at least a factor of 2. Third, the algorithm correctly identified the joint margin in more than 85% of the 105 cases tested. Automated measures of radiographic hip joint-space narrowing is less subjective than manual methods and may be applicable for monitoring OA progression in clinical research.

Acetabulum↗