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Biomedical subjects

J K Richardson

Publications and source records attributed to J K Richardson.

At least 19 recordsLinked to original sources
PubMed2001

Gender, body mass and age as risk factors for ulnar mononeuropathy at the elbow.

Factors that predispose patients to ulnar mononeuropathy at the elbow (UME) are poorly defined. We compared 112 electrodiagnostic reports which met criteria for definite or probable UME to 104 reports which excluded UME. Male gender was strongly associated with definite (OR = 6.9, 95% CI = 2.4-20.4; P < 0.001) and all UME (OR = 2.2, 95% CI = 1.2-4.1; P = 0.010) after controlling for age and body mass index (BMI). Among men, UME was associated with increasing age (P = 0.008) but not a decreased BMI. Women, however, demonstrated an association between decreased BMI and UME (OR = 2.3, 95% CI = 1.3-4.2 for BMI < or =22.0 versus >22.0). These findings, in conjunction with gender differences in ulnar motor nerve parameters among UME subjects and controls, suggest that the pathophysiology of UME differs with gender.

Age Distribution↗
PubMed2001

Mild diabetic neuropathy affects ankle motor function.

OBJECTIVE: To evaluate the effect of age and diabetic neuropathy on ankle motor function in the frontal plane in terms of rate of torque development and capability for balance recovery. DESIGN: Case control study. Six older women with diabetic neuropathy compared to six women without neuropathy, matched for age and presence of diabetes mellitus; and nine healthy young women. BACKGROUND: Neuropathy causes a distal impairment in lower extremity sensory function which increases fall risk. Impairments in ankle inversion/eversion proprioceptive thresholds have been identified, but the effect of neuropathy on ankle motor strength in the frontal plane is unknown. METHODS: Subjects' abilities to recover from a lateral lean (with center of gravity offset as percentage of foot width) while standing on one foot, and to rapidly generate inversion torque about the ankle, were quantified. RESULTS: All nine of the young, but only one of six older, control subjects recovered from a 10% lean (P=0.0052). Three of six older controls, but no neuropathy subject, recovered from a 5% lean (P=0.083). Neuropathy subjects demonstrated half the ankle rate of torque development [78.2 (50.8) N m/s; P=0.016] of the young and older controls [162.0 (54.6) and 152.7 (22.2) N m/s, respectively]. CONCLUSIONS: Diabetic neuropathy leads to a decrease in rapidly available ankle strength which impairs balance recovery among older women. Younger women demonstrate similar ankle strength but superior balance recovery compared to older women without neuropathy.

Adult↗
PubMed2001

Unipedal stance testing in the assessment of peripheral neuropathy.

OBJECTIVE: To define further the relation between unipedal stance testing and peripheral neuropathy. DESIGN: Prospective cohort. SETTING: Electroneuromyography laboratory of a Veterans Affairs medical center and a university hospital. PATIENTS: Ninety-two patients referred for lower extremity electrodiagnostic studies. MAIN OUTCOME MEASURES: A standardized history and physical examination designed to detect peripheral neuropathy, 3 trials of unipedal stance, and electrodiagnostic studies. RESULTS: Peripheral neuropathy was identified by electrodiagnostic testing in 32%. These subjects had a significantly shorter (p <.001) unipedal stance time (15.7s, longest of 3 trials) than the patients without peripheral neuropathy (37.1s). Abnormal unipedal stance time (<45s) identified peripheral neuropathy with a sensitivity of 83% and a specificity of 71%, whereas a normal unipedal stance time had a negative predictive value of 90%. Abnormal unipedal stance time was associated with an increased risk of having peripheral neuropathy on univariate analysis (odds ratio = 8.8, 95% confidence interval = 2.5--31), and was the only significant predictor of peripheral neuropathy in the regression model. Aspects of the neurologic examination did not add to the regression model compared with abnormal unipedal stance time. CONCLUSIONS: Unipedal stance testing is useful in the clinical setting both to identify and to exclude the presence of peripheral neuropathy.

Adult↗
PubMed2001

A focused exercise regimen improves clinical measures of balance in patients with peripheral neuropathy.

OBJECTIVE: To determine the effect of a specific exercise regimen on clinical measures of postural stability and confidence in a population with peripheral neuropathy (PN). DESIGN: Prospective, controlled, single blind study. SETTING: Outpatient clinic of a university hospital. PARTICIPANTS: Twenty subjects with diabetes mellitus and electrodiagnostically confirmed PN. INTERVENTION: Ten subjects underwent a 3-week intervention exercise regimen designed to increase rapidly available distal strength and balance. The other 10 subjects performed a control exercise regimen. MAIN OUTCOME MEASURES: Unipedal stance time, functional reach, tandem stance time, and score on the activities-specific balance and confidence (ABC) scale. RESULTS: The intervention subjects, but not the control subjects, showed significant improvement in all 3 clinical measures of balance and nonsignificant improvement on the ABC scale. CONCLUSION: A brief, specific exercise regimen improved clinical measures of balance in patients with diabetic PN. Further studies are needed to determine if this result translates into a lower fall frequency in this high-risk population.

Aged↗
PubMed2001

Chronic anterior compartment syndrome and deep peroneal nerve function.

OBJECTIVE: We hypothesized that athletes with chronic anterior exertional compartment syndrome (CAECS) would demonstrate an impairment in deep peroneal nerve function, as determined by electrodiagnostic studies or neuromuscular examination, either at baseline as compared with control athletes or after exercise. DESIGN: Prospective, controlled study comparing athletes with CAECS to asymptomatic athletes. SETTING: Outpatient, academic practice. PARTICIPANTS: Ten athletes with CAECS were recruited sequentially over 1 year from an outpatient academic practice; diagnosis was confirmed by history, physical examination, and compartment pressure testing. Ten similarly aged control athletes were recruited from the surrounding facility. INTERVENTION: Repetitive dorsiflexion exercise to the point of typical symptoms (CAECS subjects) or fatigue (control subjects). MAIN OUTCOME MEASURES: Deep peroneal nerve conduction study velocity and amplitude; neuromuscular examination in the deep and superficial peroneal distributions. RESULTS: Control subjects demonstrated a significant increase in peroneal motor amplitudes postexercise as compared with preexercise (6.3 +/- 2.2 mV preexercise to 8.2 +/- 3.1 mV postexercise; p = 0.033), but the CAECS subjects did not (8.8 +/- 2.6 to 8.9 +/- 2.1; p = 0.89). At baseline and postexercise, the subjects with CAECS demonstrated decreased vibratory sensation compared with the controls (p = 0.030 at baseline and 0.045 postexercise). CONCLUSIONS: Athletes with CAECS demonstrate a decreased postexercise potentiation of the peroneal motor amplitude and a mild impairment in vibratory sensation; these findings may contribute to their sense of poor foot and ankle control. Further study is necessary before the absence of postexercise potentiation of the peroneal motor amplitude may be considered a diagnostic sign of CAECS.

Adolescent↗
PubMed2000

Unipedal stance testing as an indicator of fall risk among older outpatients.

OBJECTIVE: To test the hypothesis that a decreased unipedal stance time (UST) is associated with a history of falling among older persons. DESIGN: Fifty-three subjects underwent a standardized history and physical examination and three trials of timed unipedal stance. SETTING: The electroneuromyography laboratories of tertiary care Veterans Administration and university hospitals. SUBJECTS: Ambulatory outpatients 50 years and older referred for electrodiagnostic studies. OUTCOME MEASURES: UST and fall histories during the previous year. RESULTS: Twenty subjects (38%) reported falling. Compared with the subjects who had not fallen, those who fell had a significantly shorter UST (9.6 [SD 11.6] vs 31.3 [SD 16.3] seconds, using the longest of the three trials, p < .00001). An abnormal UST (<30sec) was associated with an increased risk of having fallen on univariate analysis and in a regression model (odds ratio 108; 95% confidence interval 3.8, >100; p < .007). The sensitivity of an abnormal UST in the regression model was 91% and the specificity 75%. When UST was considered age was not a predictor of a history of falls. CONCLUSIONS: UST of <30sec in an older ambulatory outpatient population is associated with a history of falling, while a UST of > or = 30sec is associated with a low risk of falling.

Accidental Falls↗
PubMed2000

Halo vest effect on balance.

OBJECTIVE: To determine the effect of a halo vest, a cervical orthosis, on clinically relevant balance parameters. DESIGN: Subjects performed unipedal stance (with eyes open and closed, on both firm and soft surfaces) and functional reach, with and without the application of a halo vest. SUBJECTS: A convenience sample of 12 healthy young subjects, with an equal number of men and women. OUTCOME MEASURES: Seconds for unipedal stance (maximum 45); inches for functional reach. RESULTS: Both unipedal stance times and functional reach (mean +/- standard deviation) were significantly decreased with the halo vest as compared to without it (29.1+/-5.8 vs. 32.8+/-6.4 seconds, p = .002; 12.9+/-1.4 vs. 15.1+/-2.1 inches, p<.01). CONCLUSION: A halo vest causes an acute impairment in balance in the healthy young. It is likely that the impairment would be greater in older or injured patients, thus increasing their risk for a fall, which could have devastating consequences.

Adult↗
PubMed1999

An electrophysiological exploration of the double crush hypothesis.

The double crush hypothesis has not been rigorously evaluated in humans. We therefore analyzed cases of C6, C7, and C8 radiculopathy and exploited the fact that the median sensory response is of C6/C7 origin and the median motor response is primarily of C8 origin. We hypothesized that C6 and/or C7 cases would demonstrate an increased frequency of median mononeuropathy by sensory criteria, and C8 cases would demonstrate an increased frequency of median mononeuropathy by motor criteria. We also hypothesized that median sensory and motor response parameters among these same groups would be altered in ways consistent with a proximal influence on distal nerve conduction studies. Although median mononeuropathy was unexpectedly common (22.1%) among cases of cervical radiculopathy (which may explain the clinical acceptance of the double crush hypothesis), none of the hypotheses was supported. This study identified no evidence to support a neurophysiological explanation for the double crush hypothesis.

Age Factors↗
PubMed1998

Rural residents' use of cardiac rehabilitation programs.

The goal of this study was to identify the factors that influence the use of cardiac rehabilitation services by rural residents. The Andersen-Newman framework, which consists of three determinants of health services utilization (predisposing, enabling, and need factors), was used to direct this research. The three data collection points were at time of discharge from the hospital, two weeks post discharge, and one week following the date that the cardiac rehabilitation program would have been completed. Packets for the three data collection points were unique and contained instruments to assess various factors influencing the use of health services. The sample (N = 254) were adults living in rural areas who had experienced a cardiac event and received treatment at one of four hospitals in two western states and who provided useable data on all three questionnaires. Findings indicated that 72 (28%) of the participants attended some portion of a rehabilitation program, and only 43 (17%) completed the full 36-week program. Four predisposing factors, one enabling factor, and two need factors were significant in explaining the number of cardiac rehabilitation sessions attended. Further research is needed to validate these factors and to identify others which may influence the use of cardiac rehabilitation by rural residents. Likewise, it is essential to examine alternate ways to meet the rehabilitative needs of rural cardiac clients.

Adult↗
PubMed1997

A familial predisposition toward lumbar disc injury.

STUDY DESIGN: A retrospective case-control study was performed. OBJECTIVES: To test the hypothesis that there is a familial predisposition to lumbar disc pain and injury. SUMMARY OF BACKGROUND DATA: The few studies that have addressed this question have suggested that a familial predisposition is present, but the techniques used for identifying discogenic pain and accounting for potentially confounding extrinsic factors make it difficult to formulate a clear conclusion. METHODS: Immediate relatives of index patients who had surgically proven lumbar disc herniations (disc/case subjects) or repetitive upper extremity overuse syndromes (upper extremity/control subjects) were given a questionnaire that had been tested previously and found to reliably identify discogenic lower back pain. The prevalence of lumbar disc pain and injury was determined in the two groups of patients; logistic regression was used to control for demographic factors and activities known to increase risk for lumbar disc injury. RESULTS: The questionnaire was returned by 60 (59%) of 102 disc subjects and 41 (50%) of 81 upper extremity subjects. Sixteen (28%) disc subjects and one (2%) of the upper extremity subjects met questionnaire criteria for discogenic lumbar pain; seven (12%) disc subjects and no upper extremity subjects had received surgical therapy for lumbar disc pain. Logistic regression analysis identified familial grouping and a history of lifting as the only variables associated with a positive response on the questionnaire. Information obtained from index patients about their nonresponding relatives' history of significant back pain suggested similar findings. CONCLUSIONS: There is a familial predisposition toward lumbar disc pain and injury. This information may be helpful in occupational counseling or for targeting specific populations with preventative, interventional strategies.

Adult↗
PubMed1996

A cane reduces loss of balance in patients with peripheral neuropathy: results from a challenging unipedal balance test.

OBJECTIVE: To test the hypothesis that use of a cane in the nondominant hand during challenging balance tasks would significantly decrease loss of balance in patients with peripheral neuropathy while transferring from bipedal to unipedal stance on an unsteady surface. DESIGN: Nonrandomized control study. SETTING: Tertiary-care institution. PARTICIPANTS: Eight consecutive patients with peripheral neuropathy (PN) and eight age- and gender-matched controls (C) with a mean (SD) age of 65 (8.2) years. METHODS: Subjects were asked to transfer their weight onto their right foot, despite a rapid +/- 2 degrees or +/- 4 degrees frontal plane tilt of the support surface at 70% of weight transfer, and balance unipedally for at least 3 seconds. The efficacy of their weight transfer was evaluated over 112 consecutive randomized and blocked trials by calculating loss of balance as failure rates (%FR) with and without visual feedback, and with and without use of a cane in the nondominant (left) hand. Results were analyzed using a 2 x 2 x 2 x 2 x 2 repeated-measures analysis of variance (rm-ANOVA) and post hoc t tests. RESULTS: The rm-ANOVA showed that the FR of the PN subjects (47.6% [18.1%]) was significantly higher than C (29.2% [15.2%], p = .036). Removing visual feedback, simulating the dark of night, increased the FR fourfold (p = .000). Use of a cane in the contralateral nondominant hand significantly reduced the FR (p = .000), particularly in the PN group (cane x disease interaction: p = .055). Post hoc t tests showed that with or without visual feedback, the cane reduced the FR of the PN group fourfold and enabled them to perform more reliably than matched controls not using a cane (p = .011). An inversion perturbation resulted in a higher FR than an eversion perturbation (p = .007). The PN group employed larger mean peak cane forces (21.9% BW) than C (13.6% BW) in restoring their balance (p = .000). CONCLUSION: Use of a cane by PN patients significantly reduced their risk of losing balance on unstable surfaces, especially under low-light conditions.

Aged↗
PubMed1996

Moderate peripheral neuropathy impairs weight transfer and unipedal balance in the elderly.

OBJECTIVE: To quantitatively assess the performance of elderly with and without moderate, electrodiagnostically confirmed peripheral neuropathy (PN) on tasks of weight shifting and maintenance of unipedal balance. PATIENTS AND METHODS: A case control study with PN subjects selected from a computerized data bank of all patients who had undergone electrodiagnostic studies at a university-based referral center. Control subjects of similar age and same gender were selected from the same source. Clinical examination included neurological and gross motor components. Quantitative evaluation included testing while the subjects stood with a force plate under each foot. Center of reaction (CR) excursions and ground reaction forces were quantified in: (1) six trials as subjects transferred their weight from bipedal stance to unipedal stance, on command, and attempted to maintain it for at least 3 seconds; and (2) in two additional trials in which subjects held unipedal stance for as long as possible. RESULTS: No subjects in either group had difficulty with level gait, a 180-degree turn, or required examiner assistance during an eyes-closed Romberg test. Biomechanical testing revealed that although the PN group used the same time to transfer their weight onto one foot as the C group, they achieved a significantly (1) lower rate of success in reliably maintaining 3 seconds of unipedal stance (.12 vs .58, p = .021), and (2) shorter mean maximum unipedal stance time (3.8 vs 32.3sec, p < .001). Furthermore, the PN group experienced greater difficulty in maintaining unipedal stance, as evidenced by significantly greater fluctuations in their ground reaction forces. CONCLUSIONS: The demonstrated impairment in reliability of unipedal stance in elderly with PN likely contributes to their known high rate of falls. Furthermore, unipedal stance testing serves to sharpen the physical examination by verifying the functional significance of impaired distal sensation-a common finding in the elderly.

Aged↗
PubMed1996

Peripheral neuropathy: an often-overlooked cause of falls in the elderly.

Peripheral neuropathy is common in the elderly and results in impairments in distal proprioception and strength that hinder balance and predispose them to falls. The loss of heel reflexes, decreased vibratory sense that improves proximally, impaired position sense at the great toe, and inability to maintain unipedal stance for 10 seconds in three attempts all suggest functionally significant peripheral neuropathy. Physicians can help their patients with peripheral neuropathy to prevent falls by teaching them and their families about peripheral nerve dysfunction and its effects on balance and by advising patients to substitute vision for the lost somatosensory function, correctly use a cane, wear proper shoes and orthotics, and perform balance and upper extremity strengthening exercises.

Accidental Falls↗
PubMed1996

Hip, knee, and foot pain during pregnancy and the postpartum period.

BACKGROUND: Although much has been written about low back pain during pregnancy, there are few studies regarding leg, foot, and hip pain. The purpose of this study was to investigate the prevalence and characterize the nature of lower extremity pain in women of child-bearing age and to assess the impact of recent pregnancy on these symptoms. METHODS: In this case-control study, 107 consecutive postpartum women (case subjects) and 91 nulliparous women (controls) completed a questionnaire regarding hip, knee, and foot pain and potentially influencing factors. RESULTS: Postpartum subjects had more symptoms of leg and foot pain than did the controls (56% vs 37%; odds ratio [OR]=2.3; 95% confidence interval [CI], 1.2 to 4.7). A significant majority of pain (82%, P<.05) began during the second and third trimesters. Postpartum subjects also had a significantly higher prevalence of hip pain (38% vs 23%; OR=3.2; 95% CI, 1.4 to 7.0) and foot pain (31% vs 22%; OR=2.2; CI, 1.1 to 4.5). History of previous pain complaints also were found to be risk factors for lower extremity pain during pregnancy for case subjects and in the past year for controls. There was a trend toward older age as a risk factor as well. Multiple pain complaints were more common among case subjects than among controls. CONCLUSIONS: Lower extremity pain is common in women of childbearing age. Pregnant and postpartum women are more likely to develop new lower extremity symptoms than are nulliparous women. The timing of symptom onset in mid- to late pregnancy may suggest that biomechanical factors play a larger role than hormonal influences. Regular exercise appears to be neither protective against nor a risk factor for lower extremity pain during pregnancy.

Adolescent↗
PubMed1995

Peripheral neuropathy effect on ankle inversion and eversion detection thresholds.

A servo-controlled foot platform was used to quantify, in upright stance, the thresholds for sensing ankle inversion and eversion movements in seven geriatric patients with peripheral neuropathy (PN) confirmed by nerve conduction studies and seven age- and gender-matched (C) controls with normal nerve conduction function. The PN group had a 4.6-fold larger (p = 0.0026) threshold (mean [SD] 1.37 [1.74]degrees) for perceiving the presence and direction of an ankle rotation at a 75% rate of success (TH75) than did the C group (0.3[0.17]degrees). Inversion acuity was approximately twice that of eversion acuity in both groups. The PN group demonstrated better proprioceptive acuity in unipedal stance than in bipedal stance, whereas no such difference was found in the C group. Semiquantitative clinical tests of PN group proprioception at the ankle performed in the seated position failed to demonstrate significant differences from controls save in one case; however, the results of such tests at the toe were abnormal in all patients. In the geriatric population, PN is associated with deficits in ankle proprioception known theoretically to hamper maintenance of unipedal balance. It is significant that these deficits are associated with a clinically demonstrable loss of position sense at the toe but not the ankle.

Aged↗