Magnetic resonance diagnosis of posterior horn tears of the lateral meniscus using a thin axial plane: the zip sign--a preliminary study.

OBJECTIVE: The "zip" sign is a newly described form of meniscal tear progressing from the distal insertion of menisco-femoral ligaments (MFLs) through the lateral meniscal wall; the tear occurs during anterior cruciate ligament (ACL) rupture. The purpose of this study was to evaluate the zip sign on knee MRI within the context of ACL injuries. METHODS: From a series of 261 MR examinations for acute knee injury, we selected 97 patients with both MR and arthroscopic data for a retrospective blinded review. The zip sign was defined on axial thin MR sections as a straight line from the distal insertion of MFLs in association with five sagittal images lateral to the posterior cruciate ligament (PCL) where the MFLs were identified. Sensitivity and specificity in detecting lateral meniscal tears before and after having defined the zip sign were calculated. RESULTS: Sensitivity in detecting the tears of the posterior horn of the lateral meniscus (PHLM) reached 87.5% (CI 0.68-0.97) after zip sign criteria were defined. The zip sign has excellent inter-observer agreement, К>0.90. CONCLUSION: The zip sign indicates a lesion at the insertion site of MFLs into the PHLM on thin axial images associated with sagittal MR sections that may improve MR sensitivity in detecting PHLM tears.

Effects of a B-vitamin-deficient diet on exploratory activity, motor coordination, and spatial learning in young adult Balb/c mice.

Elevated homocysteine levels resulting from vitamin B deficiencies have been hypothesized to contribute to functional decline. To investigate the effects of elevated serum homocysteine on neurobehavioral performances, young adult Balb/c mice consumed a vitamin-B-deficient diet or a control diet under free-feeding and pair-fed conditions. The B-deficient diet decreased body weight and food intake but increased water ingestion. Relative to either control group, vitamin-B-deficient mice were more active in the open field and in enclosed arms of the elevated plus-maze. However, vitamin-B-deficient mice were not impaired on sensorimotor coordination and spatial learning tests, swimming to a visible platform even faster than either control group. The main effect of this diet restriction was hyperactivity with no change in anxiety, coordination, and memory. It remains to be determined whether severer deficits are demonstrable in older mice.

Patient information on phantom limb pain: a focus group study of patient experiences, perceptions and opinions.

Educating patients about their condition is regarded as a fundamental step in pain management. This study used focus groups with patients to explore their experiences and perceptions of the information on phantom pain that they received before and after amputation, and their views on improving this information. Thirty-one patients with a lower limb amputation attended one of seven focus groups. The majority reported phantom pain although there were individual variations in character, severity and persistence. There were wide variations in what people were told from occasional reports of good information to instances of people reporting little or no information from professionals. There were strong feelings that information should be given before or soon after amputation with a preference for verbal one-to-one explanations. Professionals, particularly nurses and surgeons, were regarded as the best source of information, although peer support was seen to be important. These findings indicate that people require timely up-to-date information on phantom pain which sensitively addresses the variability of the experience and provides the foundation for ongoing pain management. We propose that the information process could be improved by ensuring that professionals use standard information for patients derived from purposefully written sections in national guidelines.

C- and Adelta-fibre mediated thermal perception: response to rate of temperature change using method of limits.

Studies investigating the effect of rate of temperature change on thermal thresholds have used a variety of different methods and threshold combinations, and many display incomplete reporting of statistical analyses. It has been suggested that C- and Adelta-fibre mediated thresholds differ in their reaction to different rates of temperature change. Ten healthy female volunteers (aged 18-26 years; mean 21 +/- S.D. 2.53) undertook cold sensation (CS), warm sensation (WS), cold pain (CP) and heat pain (HP) threshold determinations on the thenar eminence of the dominant hand. Rates of temperature change of 0.5, 1, 2.5 and 4 degrees C/s were used, with a modified method of limits. Adaptation temperature was 32 degrees C and thermode size 3 cm x 3 cm. Results showed a significant increase in WS, HP and CP thresholds with increased rates of temperature change (all p < 0.001), but no significant change for CS (p = 0.653). These results suggest that thresholds with a C-fibre component (WS, HP and CP) and those that are Adelta-fibre mediated (CS) behave differently. A traditional explanation of measurement artefact alone is insufficient in rationalizing these results, with additional factors potentially involved. Slow rates of temperature change were shown to reduce mean intra-individual differences in recorded threshold values, and also to abolish ceiling effects with HP threshold determinations. Clinically, therefore, using slow rates of temperature change with method of limits has a range of benefits over and above simply minimizing measurement artefact.

Alteration of interferential current and transcutaneous electrical nerve stimulation frequency: effects on nerve excitation.

OBJECTIVES: To investigate the effects of different interferential current (IC) and transcutaneous electrical nerve stimulation (TENS) frequencies on sensory, motor, and pain thresholds. STUDY DESIGN: Single blind, repeated measures design. SETTING: Laboratory. PARTICIPANTS: Women students 18 to 30 years old (n = 24). INTERVENTIONS: Premodulated IC and square-wave TENS pulses (125micros phase duration) were applied over the median nerve at a range of frequencies in all subjects. MAIN OUTCOME MEASURES: The peak current (in milliamperes) was recorded twice at each threshold for each frequency, and averaged. RESULTS: Both IC and TENS displayed a statistically significant effect of frequency for each threshold. However, frequency effects with IC were not well defined and were of small magnitude. Pure 4kHz current (0Hz amplitude modulated frequency) with IC did not produce effects different from those produced when an amplitude modulated frequency was included. With TENS, frequency effects were very clearly observed, with a distinct increase in the current intensity at each threshold as frequency decreased. CONCLUSIONS: It is postulated that the medium frequency component of IC is the main parameter in stimulation, contrary to traditional claims of the amplitude modulated frequency being important. TENS was shown to be a more adaptable method of stimulating these nerve pathways than IC.

Small angle light scattering by large spheroids. Comparison with patterns from erythrocytes under shear.

The physical optics approximation has been used to compute small angle light scattering patterns from spheroids regarged as models for deformed red cells. According to their orientation, diagrams have been obtained whose fine structure can be very different from that resulting of the classical diffraction (existence of maxima and minima of intensity along the rings). Some experimental results for red cells suspensions under shear are shown which exhibit features very similar to the theoretical ones.

Transient hemorheology in an air-bearing viscosimeter.

Blood suspensions have been studied by using an air-bearing viscosimeter which is driven by a rotating magnetic induction. Each transient motion (rise, relaxation with zero or intermittent field) can be considered as a quasi-static motion, from which the curve viscosity-shear gradient can be obtained. Combining several transient motions allows an easier determination of the parameters describing a non newtonian fluid like blood.

Deformation and orientation of red blood cells in a simple shear flow. Theoretical study and approach at small angle light scattering.

On the basis of a simple theoretical model representing the rheological behaviour of the erythrocyte membrane, the authors have proceeded with a theoretical and experimental investigation on the light-scattering diagrams at small angles of normal red blood cells subjected to Couette flow. The results show that the light-scattering diagrams take into account not only cell deformation, but also cell orientation. The prospects for applying this method to the analytical separation of cells with different deformabilities are considered.