Biomedical subjects

A A Rodriquez

Publications and source records attributed to A A Rodriquez.

At least 19 recordsLinked to original sources

PubMed2005

Prevalence and correlates of depression among veterans with multiple sclerosis.

OBJECTIVES: To establish the prevalence of major depressive episode (MDE) in a large sample of veterans with multiple sclerosis (MS); to identify demographic characteristics, aspects of disease presentation, and perceptions of disability associated with greater concurrent risk for MDE; and to examine the relationship between MDE, service utilization, and activity participation. METHODS: Veterans with MS (n = 1,032) were identified via computer database and surveyed by mail; 451 (43.7%) responded. RESULTS: Twenty-two percent of the sample met criteria for current MDE. Low income, unemployment, presence of falls, younger age, absence of a marital partner, and high levels of perceived disability due to bowel functioning were independently associated with MDE. Disease subtype, disease duration, use of disease modifying therapies, and perceived disability due to mobility or bladder problems were unrelated to MDE. Current MDE was in turn associated with increased primary care visits and increased impact of disease upon activity participation. Similar correlates were associated with minor depressive episode. CONCLUSIONS: Unlike the general population, rates of depression in this predominantly male sample were similar to those found in predominantly female samples of persons with multiple sclerosis. Specific aspects of disability were differentially associated with depression, and depression was independently associated with increased service utilization and increased participation limitations.

Data Collection↗

PubMed1998

Physiologic assessment of botulinum toxin effects in the rat larynx.

OBJECTIVE: Botulinum toxin (BT) is a currently used treatment for spasmodic dysphonia (SD) and other related focal dystonias. The goal of this study is to provide a basis for using the rat larynx to objectively assess physiological and histological effects of BT. STUDY DESIGN: Dosages and volumes of BT injection were varied and three physiological parameters were measured. These measures included: optical density of PAS-stained laryngeal muscle after electrical stimulation, which is an indirect measure of denervation, spontaneous laryngeal muscle activity, and laryngeal movement. METHODS: A new microlaryngoscopic technique was developed, which made it possible to observe and manipulate the rat larynx endoscopically. Laryngeal movement and electromyographic (EMG) measures were made prior to injection and 3 days following BT injections of various dosages and volumes. Optical density measures were made 3 days after injection. RESULTS: Significant reductions in vocal fold motion and spontaneous laryngeal muscle activity as a function of increased BT dosage were observed. In addition, the optical density of PAS-stained laryngeal muscle after electrical stimulation was increased following BT injection. Significant volume effects in optical density were observed in the lateral thyroarytenoid and lateral cricoarytenoid muscles on the contralateral side. CONCLUSIONS: The rat laryngeal model is suitable for assessing BT effects. In addition, the three physiological variables provided useful and reliable measures of laryngeal function. It is the authors' intention to use the rat laryngeal model to further examine the physiological and histological effects of BT with the goal of developing new methods for the treatment of patients with SD and other focal dystonias.

Animals↗

PubMed1997

Electromyographic and neuromuscular variables in unstable postpolio subjects, stable postpolio subjects, and control subjects.

OBJECTIVE: To compare strength and endurance variables obtained in the quadriceps muscles of postpolio and control subjects over a 7-year interval with macro and single fiber electromyography (EMG) variables. DESIGN: A controlled inception cohort study. SETTING: Neuromuscular research laboratory of a university hospital. SUBJECTS: A cohort of 23 postpolio and 14 control subjects. All postpolio subjects had a history, physical examination, and EMG consistent with previous poliomyelitis, and had greater than antigravity strength in the quadriceps muscle tested. Unstable postpolio subjects acknowledged new quadriceps weakness over the 7-year period of the study (n = 11), and stable postpolio subjects denied new weakness of the quadriceps over the same period (n = 12). MAIN OUTCOME MEASURES: All subjects had tests of neuromuscular function of the quadriceps muscles at the onset of this study and yearly over a 7-year period. EMG variables were determined on a separate day after the seventh year of neuromuscular measurements. Neuromuscular variables measured were isometric knee extension peak torque, isometric endurance (time to inability to maintain knee extensor contraction at 40% of maximal torque), tension time index (TTI) (product of isometric endurance time and 40% of maximal torque), and recovery of torque at 10 minutes after the endurance test. EMG variables were macro EMG and single fiber EMG (jitter, fiber density, and percent blocking). RESULTS AND CONCLUSIONS: Unstable postpolio subjects did not lose strength more rapidly than stable postpolio subjects or control subjects. Unstable postpolio subjects were significantly weaker, had decreased TTI, larger macro EMG amplitude, greater jitter, blocking, and fiber density in comparison with stable postpolio subjects (all p < .05). Strength was negatively correlated with macro EMG amplitude in the stable postpolio group (p < .05). The slope of the regression line of strength over 7 years did not correlate (p > .05) with neuromuscular or EMG variables in control, stable, or unstable postpolio subjects.

Age of Onset↗

PubMed1997

Strength, endurance, and work capacity after muscle strengthening exercise in postpolio subjects.

OBJECTIVE: To determine whether a 12-week home quadriceps muscle strengthening exercise program would increase muscle strength, isometric endurance, and tension time index (TTI) in postpolio syndrome subjects without adversely affecting the surviving motor units or the muscle. DESIGN: A longitudinal study to investigate the effect of a 12-week exercise program on neuromuscular function and electromyographic variables. SETTING: Neuromuscular laboratory of a university hospital. SUBJECTS: Seven subjects were recruited from a cohort of 12 subjects who had participated in a previous exercise study. All subjects had greater than antigravity strength of the quadriceps. Upon completion of a postpolio questionnaire, all acknowledged common postpolio syndrome symptoms such as new fatigue, pain, and weakness; 6 of the 7 acknowledged new strength decline. INTERVENTION: On Mondays and Thursdays subjects performed three sets of four maximal isometric contractions of the quadriceps held for 5 seconds each. On Tuesdays and Fridays subjects performed three sets of 12 dynamic knee extension exercises with ankle weights. MAIN OUTCOME MEASURES: Neuromuscular variables of the quadriceps muscles were measured at the beginning and completion of the exercise program and included: isokinetic peak torque (ISOKPT, at 60 degrees/sec angular velocity) and total work performed of four contractions (ISOKTW), isometric peak torque (MVC), endurance (EDUR, time subject could hold isometric contraction at 40% of the initial MVC), isometric tension time index (TTI, product of endurance time and torque at 40% of MVC), and initial and final ankle weight (WGT, kg) lifted. Electromyographic variables included: fiber density (FD), jitter (MCD), and blocking (BLK) from single fiber assessment and median macro amplitude (MACRO). Serum creatine kinase (CK) was also measured initially and at 4-week intervals throughout the study. RESULTS: The following variables significantly (p < .05) increased: WGT by 47%, ISOKPT, 15%, ISOKTW, 15%; MVC, 36%; EDUR, 21%; TTI, 18%. The following variables did not significantly (p > .05) change: FD, MCD, BLK, MACRO, and CK. CONCLUSIONS: This home exercise program significantly increased strength, endurance, and TTI without apparently adversely affecting the motor units or the muscle, as the EMG and CK variables did not change.

Adult↗

PubMed1997

Transoral electromyographic recordings in botulinum toxin-injected rat larynges.

Objective assessment of muscle function following botulinum toxin injections in laryngeal muscles is difficult in human subjects. We developed a rat laryngeal model for the study of botulinum toxin injection. A new laryngoscopic technique has made it possible to observe the rat larynx endoscopically and to obtain electromyographic measurements during and after injection of toxin. The electromyographic interference pattern, fibrillation potentials, and vocal fold movement were used for analyzing dose and volume effects of injected toxin. We conclude that the lowest dosage able to produce the maximal duration of functional laryngeal impairment is 0.07 U in a volume of 0.4 microL. This model will enable us to obtain physiologic and histologic parameters that can be used to assess the selection of optimal treatment regimens with botulinum toxin for the treatment of patients with spasmodic dysphonia.

Animals↗

PubMed1997

Efficacy of repeated botulinum toxin injections as a function of timing.

This pilot study was designed to determine if the interval between repeated botulinum toxin injections influenced physiologic and histologic effects on laryngeal muscles in a rat model. The physiologic measurements included digitized videomicroscopic recording of vocal fold movement and electromyography. The histologic measurements included muscle fiber size and digitized optical density of laryngeal muscles after glycogen depletion by electrical stimulation. The results demonstrated that the effect of timing of the second injection was strongly correlated to laryngeal changes. Most notable were results in the subjects that underwent injections 6 weeks apart. We hypothesize that these findings might be related to terminal axonal sprouting with reinnervation. The results from this study help confirm and expand the validity of using the rat laryngeal model to understand the effect of botulinum toxin. Moreover, we believe that the data might be extrapolated to prove useful in predicting human responses to botulinum toxin treatment for functional dystonias such as spasmodic dysphonia.

Animals↗

PubMed1996

Gait training efficacy using a home-based practice model in chronic hemiplegia.

OBJECTIVE: The efficacy of a home practice model for gait training was evaluated in 18 hemiplegic subjects 2.3 years (range, 1 to 5) after stroke. DESIGN: Uncontrolled case series. SETTING: Referral center. SUBJECTS: Patients at least 1 year poststroke referred to an outpatient rehabilitation program. INTERVENTION: Patients were taught home programs in two or more 2- to 5-day blocks averaging 35 physical therapy (PT) contact hours (range, 9.5 to 62.5); training extended over a mean of 22 months (range, 10 to 65). Training emphasized weight bearing, balance, segmental control, stretching, and bracing. MAIN OUTCOME MEASURES: Gait changes were measured using the newly developed Wisconsin Gait Scale (WGS). The patient-rated Falls Efficacy Scale (FES) was administered before and after training to 8 subjects, and the Health Status Questionnaire (HSQ) was retrospectively administered to all subjects to appraise subjective pretraining to posttraining changes and current psychological status. RESULTS: The average WGS score significantly improved (p < .05). Patients perceived that gait training increased the quality of their functional activities (p < .05). In a subset of patients, the FES showed that fear of falling was decreased (p < .05). Perception of well-being was comparable to a normative nonstroke reference population except for physical functioning. Compared to the only other published series (using traditional outpatient programming), the current model was of comparable cost. CONCLUSION: Despite the literature indicating a plateau in mobility function by 6 months after stroke, postacute training of gait in hemiplegic subjects using a home-based training model results in improved gait and the perception of improved function. Additionally, we provide validation for the newly developed Wisconsin Gait Scale, an instrument of gait measurement that may assist in comparing outcomes.

Activities of Daily Living↗

PubMed1995

Electromyographic and neuromuscular variables in post-polio subjects.

OBJECTIVE: Post-polio subjects experience functional deterioration many years after developing acute poliomyelitis and have been shown previously to have a deficit in strength recovery after isometric activity. This study characterized the size and stability of the motor units in a group of post-polio subjects with macro and single fiber electromyography (EMG) and correlated these variables with isometric strength, endurance, "work capacity," and strength recovery after fatiguing isometric exercise. DESIGN: A cohort of 12 post-polio subjects was tested for neuromuscular function. Electromyographic variables were determined on a separate day. SETTING: Volunteers were recruited from the community and tested in our neuromuscular research laboratory. SUBJECTS: A volunteer sample was obtained from advertisements. All subjects acknowledged post-polio syndrome symptoms. MAIN OUTCOME MEASURES: Neuromuscular variables were isometric knee extension peak torque, endurance (time to exhaustion) at 40% of maximal torque, tension time index, and recovery of torque at 10 minutes. Electromyographic variables were macro EMG and single fiber EMG (percent blocking and jitter). RESULTS: Macro EMG amplitude was ninefold the control value, and both jitter and blocking were greatly increased in comparison to control values. Isometric strength significantly (p < .05) correlated negatively with macro EMG amplitude. CONCLUSIONS: The weakest subjects had the greatest number of muscle fibers within the motor unit (as measured by macro EMG amplitude). Jitter and blocking did not correlate with neuromuscular function.

Adult↗

PubMed1995

A comparison of symptoms between Swedish and American post-polio individuals and assessment of lower limb strength--a four-year cohort study.

A cohort study with initial and 4-year follow-up evaluations was performed in 78 post-polio volunteers aged 34-65 years at the time of enrolment in the study, which was made to compare post-polio individuals living in Sweden and the United States, to determine whether lower limb musculature becomes weaker over time, and to determine whether individuals with complaints of post-polio syndrome, new weakness, fatigue, walking or stair climbing difficulty were weaker or lost more strength over a 4-year interval than those individuals without such complaints. Dynametrically-measured knee extensor and flexor strength and questionnaire data were obtained initially and 4 years later. The two cohorts were fairly similar, though they differed in weight gain. The Americans gained significantly (p < 0.05) more weight than the Swedish subjects. Both groups lost significant (p < 0.05) knee extensor strength (approximately 8%), but the loss was not significantly (p < 0.05) different between the groups. Knee flexor strength did not change significantly (p < 0.05) over time. Subjects acknowledging new strength loss were not significantly (p < 0.05) weaker than those denying strength loss; however, they lost significantly (p < 0.05) more isometric knee extensor strength than the other individuals. Subjects acknowledging new fatigue, walking or stair climbing difficulty were significantly (p < 0.05) weaker in both muscle groups than those without such complaints. Subjects acknowledging post-polio syndrome were significantly (p < 0.05) weaker than those denying this symptom, but the amount of loss of strength over time was not significantly (p < 0.05) different. We conclude that the two cohorts were quite similar. Knee extensor strength decreased during the study interval. Individuals acknowledging post-polio syndrome had weaker knee extensor musculature. Subjects with new fatigue, walking difficulty, or stair climbing difficulty were weaker in both the knee extensors and the knee flexors than the other subjects. Subjects reporting new muscle weakness also had a greater decline in isometric knee extensor strength during the study interval than those without such complaint.

Adult↗

PubMed1994

Functional psychomotor deficits associated with carpal tunnel syndrome.

A reliable task was developed for investigating functional deficits associated with carpal tunnel syndrome (CTS). A rapid pinch and release psychomotor task utilizing muscles of the hand innervated by the median nerve was administered using a strain gauge dynamometer and providing limited force feedback. The motor performance characteristics studied were speed and force control. An experiment was conducted for studying the effects of force level, hand dominance, test-retest reliability, learning, and inter-subject variability using 13 subjects free from any hand disabilities or symptoms. A companion study was also conducted using 17 normal subjects and ten subjects diagnosed having CTS to investigate differences between CTS and control subjects. Dominant hands performed 4% to 8% better than the non-dominant hands by having a greater pinch rate, a smaller overshoot force, and less time above the upper force level and below the lower force level. Control subjects performed 25% to 82% better than CTS subjects. Age contributed 6% of the total variance for pinch rate and 7% of the total variance for the time below the lower force level. The results suggest that people suffering from CTS may experience similar functional psychomotor deficits in daily living and manual work activities.

Adult↗

PubMed1994

Needle electromyographic evaluation of the diaphragm.

Needle electromyography of the diaphragm is a useful tool in diagnosis and prognosis of patients with diaphragmatic dysfunction. Spontaneous activity, polyphasic motor units and decreased recruitment can be found in phrenic nerve and spinal cord injury. We describe a safe technique for studying the diaphragm using needle electrodes.

Diaphragm↗

PubMed1993

Acoustic myography compared to electromyography during isometric fatigue and recovery.

This study compared the acoustic (RMS-AMG) to electromyographic (RMS-EMG) signal, median frequency of EMG power spectrum (Fm), and quadriceps torque during isometric fatiguing contraction (FC) and recovery. Seven subjects were tested for strength (MVC) and then, on separate days, maintained 20%, 40%, or 80% MVC to exhaustion followed by MVC testing at regular intervals. Throughout FC, RMS-EMG significantly (P < 0.05) increased and Fm significantly (P < 0.05) decreased during all trials; RMS-AMG significantly (P < 0.05) increased only during the 20% and 40% trials. During recovery, MVC and RMS-EMG recovered most slowly after the 20% trial and most rapidly after the 80% trial; Fm and RMS-AMG recovered by 90 seconds after all trials. RMS-AMG reflects RMS-EMG during low but not high levels of FC. Recovery of strength is most depressed following FC at lower relative levels of torque. We conclude that RMS-AMG behaves differently than RMS-EMG, torque, and Fm during FC and recovery.

Acoustics↗

PubMed1992

Therapeutic exercise in chronic neck and back pain.

Research regarding the effect of exercise on chronic benign axial pain is reviewed. Both chronic low back pain (LBP) and chronic neck pain are associated with weakness of the trunk and neck musculature; however, it is unknown whether weakness is a cause or effect. The relationship between incoordination of the neck or trunk musculature and chronic pain is unclear. Exercise is associated with improved strength and endurance and decreased pain in subjects with LBP but the literature is very sparse with respect to chronic neck pain. Range-of-motion is also diminished in those with LBP and improves with exercise, and is associated with abatement in symptoms. No evidence could be found regarding the effect of exercise on segmental motion. Exercise is also associated with improved function, however the mechanism whereby either pain report or function improves is unclear. A greater understanding of the role of exercise will require more specific studies of strength, coordination, motion, function, and pain.

Back Pain↗

PubMed1991

Needle electromyographic evaluation of patients with myofascial or fibromyalgic pain.

Several past studies have evaluated the electromyographic activity of myofascial trigger points with conflicting results. This study was performed to determine whether spontaneous activity or motor unit activity was present in patients with focal myofascial pain or fibromyalgia. Using routine needle electromyographic techniques, we sampled reproducibly tender focal areas (tender points), similar tender areas with pain referral (trigger points), associated muscle bands and adjacent uninvolved musculature. Twenty-five subjects (14 females, 11 males, mean +/- SD age 43 +/- 14 years) were studied; twenty-one subjects with focal myofascial pain and four with fibromyalgia. Spontaneous fibrillatory or positive sharp wave potentials were not found in any muscle in the 25 subjects. There was no evidence of focal motor unit activity in the tender points, trigger points or associated muscle bands in either group. Motor unit recruitment was similar in all areas sampled. We conclude that no electrodiagnostic evidence of ongoing denervation or focal muscle spasm is found in association with focal myofascial pain or fibromyalgia.

Action Potentials↗

PubMed1991

Motor unit firing rates in postpolio and control subjects during submaximal contraction.

Postpolio patients have a deficit in strength recovery after isometric activity. The cause for this is unknown, but may be the result of higher motor unit firing rates during the activity, which leads to excessive fatigue of the motor units. The purpose of this study was to determine whether postpolio subjects recruited motor units at higher firing rates than control subjects. Twelve control and seven postpolio subjects were tested for maximal voluntary contraction of the quadriceps isometrically. Randomly, subjects performed isometric contractions for five 10-s periods freely against gravity (threshold) and at 20% and 40% of maximal voluntary contraction. Decompositional motor unit electromyographic analysis was used to measure motor unit amplitude, motor unit firing rate and counted number of motor units identified. Analysis was by univariate analysis of variance. Motor unit firing rate was not significantly greater (P greater than 0.05) in postpolio subjects than control subjects at all three levels of contraction. Thus, it is unlikely that an increased motor unit firing rate leads to the deficit in recovery of strength in postpolio subjects.

Action Potentials↗

PubMed1991

Neuromuscular function in polio survivors.

Although there is no documented, objective evidence that symptomatic post-polio subjects are rapidly losing strength, they have a number of neuromuscular deficits related to a more severe poliomyelitis illness that may explain why they complain of problems with strength, endurance, and local muscle fatigue. Symptomatic post-polio subjects were hospitalized longer during the acute poliomyelitis, recovered more slowly, and had electromyographic evidence of greater loss of anterior horn cells. Additionally, recent assessment demonstrated that they were weaker, had a reduced work capacity, and recovered strength less readily after activity in the quadriceps muscles as compared to asymptomatic subjects. Of great clinical importance, rating of perceived exertion in the muscle during exercise was the same in symptomatic and asymptomatic post-polio and control subjects, indicating that symptomatic subjects have a mechanism to monitor local muscle fatigue that could be used to avoid exhaustion. A study of pacing (interspersing activity with rest breaks) showed that symptomatic subjects had less local muscle fatigue and greater strength recovery when they paced their activity than when they worked at a constant rate to exhaustion. We recommend that post-polio individuals pace their daily activity to avoid excessive fatigue.

Electromyography↗

PubMed1991

Quantitative cervical flexor strength in healthy subjects and in subjects with mechanical neck pain.

Although weakness of anterior cervical muscles is postulated to contribute to persistent neck pain in patients with mechanical neck pain, quantitation of weakness has never been reported. We compared anterior cervical muscle strength in 30 subjects with mechanical neck pain and in 30 asymptomatic control subjects. Testing was performed with the subject supine, chin retracted, and neck flexed. Assessment was made using a hand-held dynamometer with head held at the midline and with rotation left and right within a pain-free range. Analysis with Wilcoxon scores showed that patients with neck pain had significantly less (p less than .05) strength (N.Kg-1) in all three positions than controls (1.16 +/- 0.49 vs 1.71 +/- 0.42, sagittally; 1.01 +/- 0.52 vs 1.47 +/- 0.41, rotation left; .99 +/- 0.46 vs 1.43 +/- 0.43 rotation right; neck pain vs control, respectively.) This weakness and its role in persistent neck pain should be recognized. The efficiency and effect of cervical muscle strengthening in treatment of chronic neck pain should be further defined.

Adult↗

PubMed1991

Intermittent isometric activity: its effect on muscle fatigue in postpolio subjects.

Symptomatic postpolio patients report improved function when they pace their activities, but this has never been objectively assessed. The purpose of this study was to determine whether seven symptomatic postpolio subjects would (1) have less evidence of local muscle fatigue and recover strength more readily when they pace their activity (via work-rest intervals) than when they work at a constant rate to exhaustion, and (2) be able to perform more work with less fatigue by pacing. Subjects were evaluated on three separate days with at least one week between tests. On the first test day (constant exercise), isometric peak torque (MVC) of the quadriceps was determined and an isometric endurance test was performed to exhaustion at 40% of MVC. Thirty seconds after exhaustion the subject performed an MVC. One psychophysiologic and two electrophysiologic variables associated with fatigue were measured during the testing procedure. Work capacity (TTI) was determined as torque x time. In test 2 (quartile exercise), the same TTI was performed at 40% of MVC, but in this instance the work was performed in quartiles with two-minute rest breaks between work quartiles rather than continuously to exhaustion. In test 3 (interval exercise), exercise was performed at 40% of MVC in 20-second bouts with two-minute rest breaks until rating of perceived exertion exceeded 17 (very hard), or until six-minutes of work were performed. Analyses demonstrated that both work-rest interval programs resulted in less evidence of local muscle fatigue, increased capacity to perform work, and increased ability to recover strength after activity in symptomatic postpolio patients.

Adult↗