Fear conditioning in frontotemporal lobar degeneration and Alzheimer's disease.

Emotional blunting and abnormal processing of rewards and punishments represent early features of frontotemporal lobar degeneration (FTLD). Better understanding of the physiological underpinnings of these emotional changes can be facilitated by the use of classical psychology approaches. Fear conditioning (FC) is an extensively used paradigm for studying emotional processing that has rarely been applied to the study of dementia. We studied FC in controls (n = 25), Alzheimer's disease (n = 25) and FTLD (n = 25). A neutral stimulus (coloured square on a computer screen) was repeatedly paired with a 1 s burst of 100 db white noise. Change in skin conductance response to the neutral stimulus was used to measure conditioning. Physiological-anatomical correlations were examined using voxel-based morphometry (VBM). Both patient groups showed impaired acquisition of conditioned responses. However, the basis for this deficit appeared to differ between groups. In Alzheimer's disease, impaired FC occurred despite normal electrodermal responses to the aversive stimulus. In contrast, FTLD patients showed reduced skin conductance responses to the aversive stimulus, which contributed significantly to their FC deficit. VBM identified correlations with physiological reactivity in the amygdala, anterior cingulate cortex, orbitofrontal cortex and insula. These data indicate that Alzheimer's disease and FTLD both show abnormalities in emotional learning, but they suggest that in FTLD this is associated with a deficit in basic electrodermal response to aversive stimuli, consistent with the emotional blunting described with this disorder. Deficits in responses to aversive stimuli could contribute to both the behavioural and cognitive features of FTLD and Alzheimer's disease. Further study of FC in humans and animal models of dementia could provide a valuable window into these symptoms.

Distinct MRI atrophy patterns in autopsy-proven Alzheimer's disease and frontotemporal lobar degeneration.

To better define the anatomic distinctions between Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD), we retrospectively applied voxel-based morphometry to the earliest magnetic resonance imaging scans of autopsy-proven AD (N = 11), FTLD (N = 18), and controls (N = 40). Compared with controls, AD patients showed gray matter reductions in posterior temporoparietal and occipital cortex; FTLD patients showed atrophy in medial prefrontal and medial temporal cortex, insula, hippocampus, and amygdala; and patients with both disorders showed atrophy in dorsolateral and orbital prefrontal cortex and lateral temporal cortex (P(FWE-corr) < .05). Compared with FTLD, AD patients had decreased gray matter in posterior parietal and occipital cortex, whereas FTLD patients had selective atrophy in anterior cingulate, frontal insula, subcallosal gyrus, and striatum (P < .001, uncorrected). These findings suggest that AD and FTLD are anatomically distinct, with degeneration of a posterior parietal network in AD and degeneration of a paralimbic fronto-insular-striatal network in FTLD.

Correlation of quantitative measures with the modified Ashworth scale in the assessment of plantar flexor spasticity in patients with traumatic brain injury.

This study of plantar flexor spasticity describes relationships among a traditional qualitative spasticity scale, three potential quantitative spasticity measures and a measure of voluntary ankle muscle function. Thirty-four volunteer adult patients with traumatic brain injuries participated. There were 28 males and 6 females; the mean age was 30.3 years. A battery of five randomly sequenced tests was performed for each subject on one ankle. Tests were: modified Ashworth scale (MAS) scoring; H-reflex testing with and without Achilles tendon vibration; H-reflex testing with and without dorsiflexor contraction; reflex threshold angle and timed toe tapping (TTT). Twenty-six subjects returned to have the second ankle tested, resulting in 60 ankles for the analyses. Spearman's coefficients for correlation of quantitative spasticity measures with MAS scores ranged from 0.39 to 0.49 with associated probabilities < or = 0.002. Pearson coefficients for correlation of quantitative spasticity measures with TTT scores were lower but also significant (P < or = 0.07). Multiple correlation for the set of quantitative measures yielded R = 0.614 (P < 0.001) with MAS scores and R = 0.365 (P = 0.045) with TTT scores. These findings reveal statistically significant relationships of low to moderate strength among potential quantitative spasticity measures, a traditional qualitative spasticity scale and a simple measure of voluntary ankle muscle function. Understanding these relationships is an essential part of the ongoing search for quantitative spasticity measures.

The effect of back belt use on isometric lifting force and fatigue of the lumbar paraspinal muscles.

STUDY DESIGN: A repeated measures multivariate design to assess the effect of back belts on isometric lifting force and lumbar paraspinal muscle fatigue. OBJECTIVE: To determine the efficacy of lumbar back belts in minimizing a loss in isometric force production and fatigue of lumbar paraspinal muscles. SUMMARY OF BACKGROUND DATA: Increased prevalence of back belts in industry and lack of scientific evidence supporting them suggested additional research was needed. There has been no conclusive research to substantiate manufacturer claims that use of belts reduces fatigue of lumbar paraspinals. METHODS: Twenty-four subjects, 13 men and 11 women, were tested twice: once with and once without a belt. All subjects performed a dynamic lifting task at a rate of 10 lifts per minute for 20 minutes. Surface electromyograms from the lumbar paraspinals and isometric force measurements were recorded during a static maximal isometric lift at 0, 10, and 20 minutes. Load during the dynamic task was determined as 20% of initial maximum isometric force. Electromyographic data were used to detect changes in median power spectral frequencies. Muscular fatigue was indicated by a reduction in median power spectral frequency values or a decrease in isometric force-generating capacity. RESULTS: Multivariate and univariate analyses suggest that there is no effect on lumbar paraspinal muscle fatigue or isometric lifting force production as a result of back belt use. CONCLUSIONS: These findings do not support the use of back belts for the purpose of minimizing either lumbar paraspinal muscle fatigue or a loss in isometric lifting force production.

A comparative analysis of several crutch-length-estimation techniques.

The purpose of this study was to determine which of several crutch-fitting techniques best predicts ideal crutch length. One hundred seven active-duty military volunteers were measured for crutches using each of the following methods: (1) axillary fold to heel in the supine position, (2) olecranon to opposite third fingertip, (3) olecranon to opposite fifth fingertip, (4) 77% of height, (5) height minus 16 in (40.6 cm), (6) 77% of arm span, and (7) arm span minus 16 in (40.6 cm). The subject's self-reported heights and their actual measured heights were both used in calculations involving height. Ideal crutch length was determined by an experienced orthopedic physical therapist, with placement of the axillary pad 2.5 in (6.4 cm) below the axillary fold. Mean squared error indices were then computed as the average of the squared deviations of the technique measurements from the ideal crutch length. Of the techniques studied, the two involving minor arithmetical adjustments to the subjects' self-reported height were found to be good predictors: 77% of height and height minus 16 in (40.6 cm). The poorest predictor was axilla to heel in the supine position. Finally, two additional length estimates were derived using linear regression analyses. These estimates provided the best overall predictions based on actual height and reported height. A quick-reference table for crutch-length estimates based on patient heights was developed from these regression results.

Knee extension and flexion torque as a function of thigh asymmetry.

Although tape measurement of thigh girth is a common component of a clinical knee examination, the implications of thigh girth asymmetry are not well understood. The purpose of this study was to examine the relationship between thigh girth asymmetry and torque asymmetry for extension and flexion of the knee. Thirty subjects with thigh girth asymmetry of at least 2 cm, measured at a site 15 cm proximal to the superior pole of the patella, were studied. Subjects were measured for girth at 10 sites along each thigh. Knee flexion and extension torque production were also tested on a Cybex II isokinetic dynamometer. Girth asymmetry was determined by the difference in measurements between the subjects' smaller and larger thighs. Percent girth asymmetries varied by site, with the greatest average girth asymmetry (asymmetry = 5.94%) at 16 cm proximal to the superior patellar pole. Percent peak torque asymmetries were computed from the differences between subjects' stronger vs. weaker thighs. Correlations and regressions of both extension and flexion torque asymmetries upon girth asymmetry sites showed higher associations and less error for more proximal measurements. Fair to moderate correlation coefficients (r = .37-.42, p < .05) were statistically significant for extension torque asymmetry compared with girth asymmetry at sites 12, 14, 16, and 20 cm proximal to the patella and for flexion torque asymmetry only at the 14-cm site. Although girth and torque asymmetries were found to be somewhat related, percent girth asymmetry provided only a limited prediction of percent peak torque asymmetry.

Effects of the forearm support band on wrist extensor muscle fatigue.

STUDY DESIGN: A crossover experimental design with repeated measures. OBJECTIVE: To determine whether the forearm support band alters wrist extensor muscle fatigue. BACKGROUND: Fatigue of the wrist extensor muscles is thought to be a contributing factor in the development of lateral epicondylitis. The forearm support band is purported to reduce or prevent symptoms of lateral epicondylitis but the mechanism of action is unknown. METHODS AND MEASURES: Fifty unimpaired subjects (36 men, 14 women; mean age = 29 +/- 6 years) were tested with and without a forearm support band before and after a fatiguing bout of exercise. Peak wrist extension isometric force, peak isometric grip force, and median power spectral frequency for wrist extensor electromyographic activity were measured before and after exercise and with and without the forearm support band. A 2 x 2 repeated measures multivariate analysis of variance was used to analyze the data, followed by univariate analysis of variance and Tukey's multiple comparison tests. RESULTS: Peak wrist extension isometric force, peak grip isometric force, and median power spectral frequency were all reduced after exercise. However, there was a significant reduction in peak grip isometric force and peak wrist extension isometric force values for the with-forearm support band condition (grip force 28%, wrist extension force 26%) compared to the without-forearm support band condition (grip force 18%, wrist extension force 15%). CONCLUSIONS: Wearing the forearm support band increased the rate of fatigue in unimpaired individuals. Our findings do not support the premise that wearing the forearm support band reduces muscle fatigue in the wrist extensors.

M-wave stability in H-reflex testing: analysis of three rejection criteria.

Two criteria reported in recent literature were compared with the criterion of 95% probability (using analysis of variance) for their abilities to detect significant differences in M-waves due to repositioning of the ankle joint during human soleus H-reflex testing. Data from five normal adult males were analyzed using all three rejection criteria, and results from the three analyses were compared. Variability of M-wave amplitudes within a condition was found to be quite small. Commonly used M-wave rejection criteria which do not account for within-condition variability of M-waves were shown to do a relatively poor job of detecting alterations of M-wave amplitude due to a change in ankle position.

The effect of the median nerve compression test on median nerve conduction across the carpal tunnel.

INTRODUCTION: We conducted an experimental, single-blind research study to determine the efficacy of using the median nerve compression test (MNCT) to improve the sensitivity and specificity of median nerve motor and sensory latencies for the diagnosis of carpal tunnel syndrome (CTS). We expected post-MNCT latencies to be prolonged in the CTS group. METHODS: A convenience sample of 18 subjects aged 18-65 was enrolled in this study. The CTS group consisted of 9 subjects with 14 hands tested having clinical signs and symptoms of CTS and normal baseline latency measures. The control group consisted of 9 gender- and age-matched (+/- 3 years) subjects with 14 hands tested. Three standard distal sensory latencies (DSL) and one distal motor latency (DML) were obtained, then repeated after application of the MNCT. RESULTS: No significant differences in latencies were found between groups (p = 0.76) or within subjects (p = 0.74) after application of the MNCT. There was less than 10% increase in sensitivities of post-MNCT latencies. DISCUSSION AND CONCLUSION: We found that the MNCT did not cause a meaningful increase in sensitivity or specificity of latencies for the diagnosis of CTS. The use of the MNCT as a method to prolong standard latencies is not recommended.

Test-retest reliability of the ulnar F-wave minimum latency versus ulnar distal motor latency in healthy adults.

BACKGROUND AND PURPOSE: The purposes of this study were to explore reliability of the ulnar F-wave minimum latency (Fmin) and the ulnar distal motor latency (DML) and to contrast those levels of reliability in order to reveal whether physiologic lability is the primary contributor to unwanted variability in Fmin measurements. SUBJECTS AND METHODS: Fmin and DML in the Abductor Digiti Minimi muscle were measured bilaterally by two raters in 50 healthy adults (n = 100 hands, 70 male, 30 female) with 3-14 days between testing sessions. RESULTS: Intrarater reliability (ICC 3,1) for the Fmin was 0.89 with a standard error of the measurement (SEM) of 0.77 msec. Interrater reliability (ICC 2,1) for the Fmin was 0.80 with a SEM of 1.04 msec. Intrarater reliability (ICC 3,1) for the DML was 0.71 with a SEM of 0.18 msec. Interrater reliability (ICC 2,1) for the DML was 0.76 with a SEM of 0.19 msec. DISCUSSION AND CONCLUSIONS: Contrary to our hypothesis, the Fmin had a higher reliability than the DML. The DML did not display the high reliability other investigators have reported. We conclude the Fmin is a reliable measurement when 10 supramaximal stimulations are administered to healthy, young to middle-aged adult subjects. However, no inferences were made regarding relative levels of psychologic lability for the two latencies.

Test-retest reliability of the ulnar F-wave minimum latency in normal adults.

BACKGROUND AND PURPOSE: The purpose of this study was to measure the test-retest reliability of the ulnar F-wave minimum latency (Fmin) in normal adults. A reliable Fmin measure allows clinicians to ascribe changes in latency to true changes in a subject and not merely random daily variation. SUBJECTS AND METHODS: Fmin in the Abductor Digiti Minimi muscle was measured bilaterally in 49 healthy adults (n = 98) with a three day separation between tests. RESULTS: The Fmin reliability estimate as measured by intraclass correlation coefficient (3,1) was 0.59 with a standard error of measurement (SEM) of 1.3 msec. A paired t-test showed no significant difference (t = 1.7, df = 97, p > 0.05) between the mean scores from the two testing sessions. DISCUSSION AND CONCLUSIONS: We found moderate reliability and relatively low precision (high SEM) in Fmin scores taken from healthy individuals on two separate days. Strict adherence to our protocol and an acceptable overall precision of measurements (as measured by mean scores) suggest the contributions of rater and instrument error were low in our study. We conclude that 1) valid clinical interpretation of minimum F-wave latency findings is questionable because the Fmin measurement appears to have only moderate reliability, and 2) the lability of the phenomenon itself is the most likely contributor to variability in the Fmin latencies. Further research is warranted before electrophysiologists may be justified in attributing small changes in the Fmin to actual changes in the subject.

Sensitivity of qualitative and quantitative spasticity measures to clinical treatment with cryotherapy.

This study examined the extent to which a battery of tests could detect a reduction of plantarflexor spasticity resulting from cryotherapy. The tests included a traditional qualitative spasticity scale, three potential quantitative spasticity measures and a measure of voluntary ankle muscle function. Twenty-six adult traumatic-brain-injured subjects were examined; these included 22 males and 4 females. The mean age was 28.15 years (range: 18-57, SD 10.78). The five tests were performed in random sequence on both ankles of each subject, before and after a 20 minute cold pack application to the calf. Tests were: modified Ashworth scale (MAS) scoring; H-reflex testing with and without dorsiflexor contraction (Hdf/Hctrl ratio); H-reflex testing with and without Achilles tendon vibration (Hvib/Hctrl ratio); reflex threshold angle (RTA) and timed toe tapping (TIT). Cryotherapy resulted in lowered MAS scores consistent with a reduction in spasticity. Doubly multivariate repeated measures ANOVA revealed a significant difference (F = 24.16, P < 0.001) in test scores between the pre- and post-cryotherapy test batteries. Significant pre- and post-cryotherapy differences (P < or = 0.03) for all dependent measures contributed to the main effect for cryotherapy. However, among the potential quantitative measures of spasticity only the RTA test demonstrated appropriate sensitivity to the reduction in spasticity. In spite of spasticity reduction, TIT performance was impaired following muscle cooling. Failure of the H-reflex ratios to show a reduction consistent with reduced spasticity was attributed to competing alpha and gamma motoneuron effects resulting from peripheral cooling.

Reliability of the Modified Ashworth Scale in the assessment of plantarflexor muscle spasticity in patients with traumatic brain injury.

Although the Modified Ashworth Scale (MAS) is commonly used to assess the severity of muscle spasticity for ankle plantarflexors, its reliability has only been established for elbow muscles. Interrater reliability, intrarater reliability and temporal (between-days) reliability were examined in this study. Also, interrater reliability for use of the scale with plantarflexors was compared with reported results from the measurement of elbow flexors. Thirty adult volunteers with traumatic brain injuries participated. There were 20 men and 10 women; the mean age was 28.3 years (SD = 10.8). Two physical therapists used the MAS to score the subjects independently. Measurements were repeated to yield multiple scores for intrarater reliability assessment. Twenty-one of the subjects returned individually on separate days to be measured again, so that temporal reliability could be assessed. Spearman's correlation coefficients were 0.73 for interrater reliability 0.74 and 0.55 for intrarater reliability, and 0.82 for temporal reliability. Overall, reliability of the MAS for assessing plantarflexor spasticity in patients with traumatic brain injury was found to be minimally adequate to support its continued use. However, interrater reliability was less than that which has been reported for elbow flexors, and intrarater reliability findings were mixed.

Reliability, reference values and predictor variables of the ulnar sensory nerve in disease free adults.

OBJECTIVE: The purposes of this descriptive and exploratory study were to examine electrophysiological measures of ulnar sensory nerve function in disease free adults to determine reliability, determine reference values computed with appropriate statistical methods, and examine predictive ability of anthropometric variables. METHODS: Antidromic sensory nerve conduction studies of the ulnar nerve using surface electrodes were performed on 100 volunteers. Reference values were computed from optimally transformed data. Reliability was computed from 30 subjects. Multiple linear regression models were constructed from four predictor variables. RESULTS: Reliability was greater than 0.85 for all paired measures. Responses were elicited in all subjects; reference values for sensory nerve action potential (SNAP) amplitude from above elbow stimulation are 3.3 µV and decrement across-elbow less than 46%. No single predictor variable accounted for more than 15% of the variance in the response. CONCLUSION: Electrophysiologic measures of the ulnar sensory nerve are reliable. Absent SNAP responses are inconsistent with disease free individuals. Reference values recommended in this report are based on appropriate transformations of non-normally distributed data. No strong statistical model of prediction could be derived from the limited set of predictor variables. SIGNIFICANCE: Reliability analyses combined with relatively low level of measurement error suggest that ulnar sensory reference values may be used with confidence.

The anatomy of category-specific object naming in neurodegenerative diseases.

Neuropsychological studies suggest that knowledge about living and nonliving objects is processed in separate brain regions. However, lesion and functional neuroimaging studies have implicated different areas. To address this issue, we used voxel-based morphometry to correlate accuracy in naming line drawings of living and nonliving objects with gray matter volumes in 152 patients with various neurodegenerative diseases. The results showed a significant positive correlation between gray matter volumes in bilateral temporal cortices and total naming accuracy regardless of category. Naming scores for living stimuli correlated with gray matter volume in the medial portion of the right anterior temporal pole, whereas naming accuracy for familiarity-matched nonliving items correlated with the volume of the left posterior middle temporal gyrus. A previous behavioral study showed that the living stimuli used here also had in common the characteristic that they were defined by shared sensory semantic features, whereas items in the nonliving group were defined by their action-related semantic features. We propose that the anatomical segregation of living and nonliving categories is the result of their defining semantic features and the distinct neural subsystems used to process them.

Behavioral features in semantic dementia vs other forms of progressive aphasias.

OBJECTIVE: To compare the behavioral profiles in different variants of primary progressive aphasia (PPA). METHODS: We classified 67 patients with PPA into three clinical variants: semantic dementia (SEMD), progressive nonfluent aphasia (PNFA), and logopenic progressive aphasia (LPA), and we compared the severity of behavioral dysfunction, as measured by the Neuropsychiatric Inventory, in these groups and patients with frontotemporal dementia (FTD) and Alzheimer disease (AD). RESULTS: SEMD was associated with significantly more socioemotional behavioral dysfunction than the other two variants of PPA and than AD, specifically more disinhibition, aberrant motor behavior, and eating disorders-behaviors that are typical of FTD. In contrast, PNFA and LPA did not differ from each other or from AD in the type or severity of behavioral dysfunction. Behavioral abnormalities increased in severity with disease duration in SEMD, but this association was not detected in PNFA or LPA. CONCLUSIONS: Semantic dementia is associated with significantly more behavioral dysfunction than other variants of primary progressive aphasia, specifically behavioral features typical of frontotemporal dementia.

Effectiveness of manual physical therapy and exercise in osteoarthritis of the knee. A randomized, controlled trial.

BACKGROUND: Few investigations include both subjective and objective measurements of the effectiveness of treatments for osteoarthritis of the knee. Beneficial interventions may decrease the disability associated with osteoarthritis and the need for more invasive treatments. OBJECTIVE: To evaluate the effectiveness of physical therapy for osteoarthritis of the knee, applied by experienced physical therapists with formal training in manual therapy. DESIGN: Randomized, controlled clinical trial. SETTING: Outpatient physical therapy department of a large military medical center. PATIENTS: 83 patients with osteoarthritis of the knee who were randomly assigned to receive treatment (n = 42; 15 men and 27 women [mean age, 60 +/- 11 years]) or placebo (n = 41; 19 men and 22 women [mean age, 62 +/- 10 years]). INTERVENTION: The treatment group received manual therapy, applied to the knee as well as to the lumbar spine, hip, and ankle as required, and performed a standardized knee exercise program in the clinic and at home. The placebo group had subtherapeutic ultrasound to the knee at an intensity of 0.1 W/cm2 with a 10% pulsed mode. Both groups were treated at the clinic twice weekly for 4 weeks. MEASUREMENTS: Distance walked in 6 minutes and sum of the function, pain, and stiffness subscores of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). A tester who was blinded to group assignment made group comparisons at the initial visit (before initiation of treatment), 4 weeks, 8 weeks, and 1 year. RESULTS: Clinically and statistically significant improvements in 6-minute walk distance and WOMAC score at 4 weeks and 8 weeks were seen in the treatment group but not the placebo group. By 8 weeks, average 6-minute walk distances had improved by 13.1% and WOMAC scores had improved by 55.8% over baseline values in the treatment group (P < 0.05). After controlling for potential confounding variables, the average distance walked in 6 minutes at 8 weeks among patients in the treatment group was 170 m (95% CI, 71 to 270 m) more than that in the placebo group and the average WOMAC scores were 599 mm higher (95% CI, 197 to 1002 mm). At 1 year, patients in the treatment group had clinically and statistically significant gains over baseline WOMAC scores and walking distance; 20% of patients in the placebo group and 5% of patients in the treatment group had undergone knee arthroplasty. CONCLUSIONS: A combination of manual physical therapy and supervised exercise yields functional benefits for patients with osteoarthritis of the knee and may delay or prevent the need for surgical intervention.