Keith C. Hayes

Nerve supply of the human knee and its functional importance

This investigation utilized gross dissections, histolog ical preparations, and neurophysiologic experiments to gain an improved understanding of the innervation of the human knee. Anatomical illustrations represent the findings of dissections of 15 fresh amputation specimens. Neurohistologic preparations using silver staining techniques demonstrate the rich innervation of the soft tissues of the knee, and a variety of spe cialized receptors are identified. In 10 subjects with normal knees, an experimentally produced knee ef fusion of 60 cc was found to result in profound inhi bition of reflexly evoked quadriceps contraction. Clin ical implications of the anatomical and physiologic data are discussed.

The development of evidence-informed physical activity guidelines for adults with spinal cord injury.

Objectives:To systematically develop evidence-informed physical activity guidelines to improve physical fitness in people with spinal cord injury (SCI).Setting:This study was conducted in CanadaMethods:The Appraisal of Guidelines, Research and Evaluation II guideline development protocol was used to develop exercise guidelines to improve physical capacity and muscular strength. The evidence base for the guideline development process consisted of a systematic review and quality appraisal of research examining the effects of exercise on physical fitness among people with SCI. A multidisciplinary expert panel deliberated the evidence and generated the guidelines. Pilot testing led to refinement of the wording and presentation of the guidelines.Results:The expert panel generated the following guidelines: for important fitness benefits, adults with a SCI should engage in (a) at least 20 min of moderate to vigorous intensity aerobic activity two times per week and (b) strength training exercises two times per week, consisting of three sets of 8–10 repetitions of each exercise for each major muscle group.Conclusion:People with SCI, clinicians, researchers and fitness programmers are encouraged to adopt these rigorously developed guidelines.

Neck flexor muscle strength, efficiency, and relaxation times in normal subjects and subjects with unilateral neck pain and headache

OBJECTIVE To determine the test-retest reliability of a new method for measuring muscular strength, efficiency, and relaxation times of the neck flexor musculature of healthy adults, and to compare these neck flexor muscle properties in subjects who have unilateral neck pain and headache with those in controls. DESIGN Subjects lay supine and isometrically flexed their necks against a force transducer attached to the back of a webbing and velcro helmet. Electromyograms (EMGs) were recorded from surface electrodes on the sternocleidomastoid (SCM) muscles. Two consecutive sessions of five contractions of varying levels of effort from minimal through moderate and maximal effort were analyzed. SETTING Ambulatory referral center. PARTICIPANTS Volunteer control subjects (n = 10, 3 men and 7 women) were recruited from hospital and university personnel. Volunteer neck pain subjects (n = 10, 3 men and 7 women) were recruited from a physiatric chronic pain practice and a hospital outpatient physical therapy practice. RESULTS In the controls, the intraclass correlation coefficients (ICCs) for the first two maximum neck flexion contractions were; peak force ICC = .81; peak force/body weight ICC = .75; average force ICC = .75; force relaxation time ICC = .73; SCM EMG relaxation times: right ICC = .60 and left ICC = .67. Comparing sessions 1 and 2 the intraclass correlations for SCM efficiencies were right ICC = .58 and left ICC = .97. The peak force in controls (mean = 45.3 +/- 17.6N) was reduced by 50% in the neck pain subjects (mean = 22.4 +/- 13.1N) (p = .004). Similarly, peak force/body weight in the neck pain subjects (X = 0.3 +/- 0.2N/kg) was 46% of control (mean = 0.7 +/- 0.2N/kg) (p = .001), and average force in the neck pain subjects (X = 12.1 +/- 7.5N) was 43% of controls (mean = 28.5 +/- 11.0N) (p = .001). In two neck pain subjects. SCM, EMG and force relaxation times were abnormally long in both the affected and the unaffected SCM muscles, exceeding the control values by greater than 3 standard deviations. The difference between the right SCM efficiency of the control subjects (mean = 0.3 +/- 0.2N/ microV) and the affected SCM efficiency of the neck pain subjects (mean = 0.1 +/- 0.1 N/microV) approached the p < .05 criterion for significance (p = .055). CONCLUSION The technique was found to be highly reliable for the measurement of neck flexor peak force, peak force/body weight, average force, and force relaxation time, and moderately reliable for the quantitation of SCM EMG relaxation times and SCM efficiency. All force values were significantly lower in the neck pain population compared with the controls. In the neck pain population, force and SCM EMG relaxation times, as well as efficiencies, suggested abnormalities. Neck pain subjects showed no significant differences in SCM EMG relaxation time or SCM efficiency between affected and unaffected SCM muscles.

Leisure time physical activity in a population-based sample of people with spinal cord injury part I: demographic and injury-related correlates.

OBJECTIVES To estimate the number of minutes a day of leisure time physical activity (LTPA) performed by people with chronic spinal cord injury (SCI) and to identify the demographic and injury-related characteristics associated with LTPA in a population-based sample of people with chronic SCI. DESIGN Cross-sectional telephone survey. SETTING General community. PARTICIPANTS Men and women with SCI (N=695). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The number of minutes/day of LTPA performed at a mild intensity or greater. RESULTS Respondents reported mean minutes +/- SD of 27.14+/-49.36 of LTPA/d; however, 50% reported no LTPA whatsoever. In a multiple regression analysis, sex, age, years postinjury, injury severity, and primary mode of mobility each emerged as a unique predictor of LTPA. Multiple correspondence analysis indicated that being a man over the age of 34 years and greater than 11 years postinjury was associated with inactivity, while being a manual wheelchair user and having motor complete paraplegia were associated with the highest level of daily LTPA. CONCLUSIONS Daily LTPA levels are generally low in people with SCI. Women, older adults, people with less recent injuries, people with more severe injuries, and users of power wheelchairs and gait aids are general subgroups that may require special attention and resources to overcome unique barriers to LTPA. Specific subgroups may also require targeted interventions.

Effect of exercise on postural sway in the elderly

Fifty female subjects, aged 72-92 (mean 82) years, were enrolled in a 12-week (36 classes) exercise program aimed at increasing postural stability. Subjects were residents of sheltered apartments, rest homes or nursing homes, well enough and mobile enough to participate in the classes. The subjects were randomized into an exercise or a control group. Their postural sway, standing at rest on a force platform, was measured with eyes open and eyes closed. The groups were well matched in all respects. The results showed no improvement in the postural sway as a result of the exercise program. We hypothesize that increasing postural sway in the elderly represents a deterioration in, for the most part, the nervous system and may at this extreme of life indicate an irreversible loss of function. For this reason no improvement in postural sway may be possible.

Greater daily leisure time physical activity is associated with lower chronic disease risk in adults with spinal cord injury

The objective of this study was to examine the relationship between leisure time physical activity (LTPA) and common risk factors for cardiovascular disease (CVD) and type 2 diabetes in community-dwelling adults with chronic spinal cord injury (SCI). LTPA was measured using the Physical Activity Recall Assessment for People with SCI in 76 men and women with chronic (> or =1 year) paraplegia or tetraplegia, living in or near Hamilton, Ontario. Body mass index (BMI), waist circumference, body composition (fat mass (FM) and fat-free mass (FFM)), blood pressure, and biochemical data were collected. Thirty-seven percent (n = 28 participants) were inactive, reporting no LTPA whatsoever, and were compared with an equal-sized group consisting of the most active study participants (> or =25 min of LTPA per day). After adjusting for significant covariates, BMI (18.7%), %FM (19.4%), and C-reactive protein (143%) were all lower, and %FFM was higher (7.2%), in active participants (all p < or = 0.05). Ten percent of active participants vs. 33% of inactive participants were insulin resistant (p = 0.03). Waist circumference (17.6%) and systolic blood pressure (15.3%) were lower in active vs. inactive participants with paraplegia (both p < or = 0.05), but not tetraplegia. In conclusion, greater daily LTPA is associated with lower levels of selected CVD and type 2 diabetes risk factors in individuals living with SCI. Whether this relationship translates into a lower incidence of these chronic diseases has yet to be determined.

Pharmacokinetics of an Immediate‐Release Oral Formulation of Fampridine (4‐Aminopyridine) in Normal Subjects and Patients with Spinal Cord Injury

Plasma concentration profiles of the K+ channel‐blocking compound Fampridine were obtained from (1) control subjects (n = 6) following oral administration of doses of 10, 15, 20, and 25 mg and (2) patients with spinal cord injury (SCI) (n = 11) following a single oral dose of 10 mg of an immediate‐release formulation. Plasma concentrations were determined using a reversed‐phase ion‐pair high‐performance liquid chromatography (HPLC) assay with ultraviolet light detection employing liquid extraction. The drug was rapidly absorbed with a tmax ∼1 hour for both groups; tmax was independent of dose. Cmax and AUC0‐∞ were linearly related to dose, and t1/2 was 3 to 4 hours for both groups. There were no obvious differences in the (10‐mg) plasma concentration profiles between control subjects and SCI patients. The drug was well tolerated, with only mild and transient side effects of light‐headedness, dysesthesias, and dizziness.

Preclinical trial of 4-aminopyridine in patients with chronic spinal cord injury

4-Aminopyridine (4-AP) is a K+ channel blocking agent that enhances nerve conduction through areas of demyelination by prolonging the duration of the action potential and increasing the safety factor for conduction. We have investigated the effects of 4-AP (24 mg total dose-intravenous) in 6 patients with spinal cord injury (3 complete, 3 incomplete) with the intent of overcoming central conduction block, or slowing, due to demyelination. Vital signs remained stable and only mild side effects were noted. The 3 patients with incomplete injuries all demonstrated enhanced volitional EMG interference patterns and one patient exhibited restored toe movements. The changes were reversed on drug washout. There were no changes in segmental reflex activities. These results are consistent with those obtained from 4-AP trials with animal models of spinal cord injury, showing modest therapeutic benefit attributable to enhanced central conduction.

Establishing evidence-based physical activity guidelines: methods for the Study of Health and Activity in People with Spinal Cord Injury (SHAPE SCI)

Study design:Prospective, observational cohort study.Objectives:This paper describes the rationale and methodology for the Study of Health and Activity in People with Spinal Cord Injury (SHAPE SCI). The study aims to (1) describe physical activity levels of people with different injury levels and completeness, (2) examine the relationship between physical activity, risk and/or presence of secondary health complications and risk of chronic disease, and (3) identify determinants of physical activity in the SCI population.Setting:Ontario, Canada.Methods:Seven hundred and twenty men and women who have incurred a traumatic SCI complete self-report measures of physical activity, physical activity determinants, secondary health problems and subjective well-being during a telephone interview. A representative subsample (n=81) participate in chronic disease risk factor testing for obesity, insulin resistance and coronary heart disease. Measures are taken at baseline, 6 and 18 months.Conclusion:SHAPE SCI will provide much-needed epidemiological information on physical activity patterns, determinants and health in people with SCI. This information will provide a foundation for the establishment of evidence-based physical activity guidelines and interventions tailored to the SCI community.

Sustained improvements in neurological function in spinal cord injured patients treated with oral 4-aminopyridine: three cases

Preclinical trials of intravenously administered 4-Aminopyridine (4-AP) have demonstrated transient improvements in neurological function in patients with longstanding spinal cord injury (SCI). The present report describes three patients with SCI who responded favourably in preclinical trials and who were subsequently administered oral (capsule) 4-AP (10 mg b.i.d. or t.i.d.) over a 4 month interval. The three patients (two male: 1 female) all had incomplete tetraplegia (ASIA levels C and D) with the neurological level of the lesion between C5-C7. Following the administration of 4-AP the patients demonstrated marked and sustained reductions in upper (n=1) or lower extremity (n=2) spasticity. Other clinical benefits of 4-AP were reduced pain (n=1), restored muscle strength (n=3), improved sensation (n=2), voluntary control of bowel function (n=1), and sustained penile tumescence (n=2). The patients exhibited improved hand function (n=1), enhanced mobility in transfers and gait (n=2), with improved energy and endurance. Only trivial side effects (transient lightheadedness) were observed. In one case, the enhanced neurological function allowed the patient to stand with support for the first time post injury (16 years). The time course of therapeutic response to the initial dose matched the pharmacokinetic elimination profile derived from serum and urine analysis. There was no evidence of renal or hepatic toxicity with prolonged use. These results indicate a therapeutic benefit of oral 4-Aminopyridine in the management of various neurological deficits in a select group of SCI patients.