Kurt A. Mossberg

Effect of Growth Hormone Replacement Therapy on Cognition after Traumatic Brain Injury

Traumatic brain injury (TBI) is a major public health issue, and yet medical science has little to offer for the persistent symptoms that prevent many of these individuals from fully re-entering society. Post-traumatic hypopituitarism, and specifically growth hormone deficiency (GHD), has been found in a large percentage of individuals with chronic moderate to severe TBI. Presently, there are no published treatment studies of hormone replacement in this population. In this study, 83 subjects with chronic TBI were screened for hypopituitarism. Forty-two subjects were found to have either GHD or GH insufficiency (GHI), of which 23 agreed to be randomized to either a year of GH replacement or placebo. All subjects completed the study with no untoward side effects from treatment. A battery of neuropsychological tests and functional measures were administered before and after treatment. Improvement was seen on the following tests: Dominant Hand Finger Tapping Test, Wechsler Adult Intelligence Scale III-Information Processing Speed Index, California Verbal Learning Test II, and the Wisconsin Card Sorting Test (executive functioning). The findings of this pilot study provide preliminary evidence suggesting that some of the cognitive impairments observed in persons who are GHD/GHI after TBI may be partially reversible with appropriate GH replacement therapy.

Reliability of a timed walk test in persons with acquired brain injury

Mossberg KA: Reliability of a timed walk test in persons with acquired brain injury. Am J Phys Med Rehabil 2003;82:385–390. Objective The purpose of this study was to assess the reliability of a 6-min walk test in individuals with acquired brain injury. Design A total of 23 clients (14 men, 9 women) participated. All participants were clients in a postacute residential rehabilitation facility. The time from injury averaged 12 mo (range, 7–38 mo). Subjects were instructed to walk around a rectangular track as many times as possible during a period of 6 min. The test was performed twice, separated by 1–10 days. Heart rate was monitored continuously throughout the test, and distance traveled was recorded in meters after completion. A physiologic cost index (beats per meter) was calculated. Intraclass correlation coefficients were calculated for distance traveled, heart rate responses, and physiologic cost index. Results The mean distance walked was 403 ± 105 m (trial 1) and 417 ± 106 m (trial 2). The intraclass correlation coefficient for distance was 0.94. The mean steady-state heart rate was 118 ± 21 beats/min (trial 1) and 117 ± 20 beats/min (trial 2), and the intraclass correlation coefficient was 0.65. The mean physiologic cost index was 0.52 ± 0.19 beats/m (trial 1) and 0.55 ± 0.22 beats/m (trial 2), and the intraclass correlation coefficient was 0.89. Conclusions Distance traveled and the physiologic cost index demonstrated excellent reliability, whereas heart rate responses for individual minutes demonstrated only fair reliability. The individuals studied were very consistent in their efforts, despite a combination of physical and cognitive impairments. The results suggest that the 6-min walk test can be used reliably in the assessment of functional ambulation in persons with acquired brain injury.

Reliability of static standing balance in nondisabled children: comparison of two methods of measurement

Static standing balance is commonly measured with research laboratory systems (LabSys) or clinical systems (ClinSys). The purposes of this study were to (1) assess the reliability of two systems designed to measure static standing balance in nondisabled children, (2) compare the findings derived from the two systems of measurement, and (3) examine the relationship between anthropometric measures and postural sway. Twenty-five nondisabled children (12 male, 13 female) ages 1 year 11 months to 12 years 2 months (mean = 6 years 4 months; SD = 4 years 3 months) participated in the study. Each child stood on the LabSys and the ClinSys for three consecutive 10 second measurement periods. Intraclass correlation coefficients (ICC (2, 1)) for the three trials on each system were 0.62 (LabSys) and 0.63 (ClinSys). The level of agreement between the two systems was 0.61 (ICC (2, 1)). Younger children exhibited more variability and less agreement between measurement trials using the ClinSys. However, older children demonstrated more similar sway indices when comparing the two systems of measurement. Two-way analysis of variance indicated that there were significant differences between sway indices measured by the two systems (p < 0.01) and between the youngest children (aged 2-4 years) and all other children (p < 0.01). In addition, agreement among trials for the two systems was different depending on the age group measured. Correlation coefficients for sway index and age, height, weight, and foot length ranged from -0.52 to -0.64 for the LabSys (p < 0.01) and -0.62 to -0.73 for the Clin-Sys (p < 0.01). Stepwise multiple regression analysis indicated that height was the most significant predictor of sway when measured by the ClinSys (R2 = 0.536, p < 0.01) whereas age was the most significant predictor when sway was measured using the LabSys (R2 = 0.403, p < 0.01). The results suggest that the degree of postural sway and the reliability of the measurement itself are influenced by the age of the child and the measurement system employed.

Endurance training and cardiorespiratory conditioning after traumatic brain injury

ObjectiveTo examine the importance of cardiorespiratory conditioning after traumatic brain injury (TBI) and provide recommendations for patients recovering from TBI. MethodReview of literature assessing the effectiveness of endurance training programs. Main outcomes and resultsA sedentary lifestyle and lack of endurance are common characteristics of individuals with TBI who have a reduction in peak aerobic capacity of 25% to 30% compared with healthy sedentary persons. Increased physical activity and exercise training improves cardiorespiratory fitness in many populations with physical and cognitive impairments. Therefore, increasing the endurance and cardiorespiratory fitness of persons with TBI would seem to have important health implications. However, review of the TBI literature reveals that there have been few well-designed, well-controlled studies of physiologic and psychological adaptations of fitness training. Also lacking are long-term follow-up studies of persons with TBI. ConclusionsAssessing endurance capacity and cardiorespiratory fitness early in the TBI rehabilitation process merits consideration as a standard of care by professional rehabilitation societies. Also, providing effective, safe, and accessible training modalities would seem to be an important consideration for persons with TBI, given the mobility impairments many possess. Long-term follow-up studies are needed to assess the effectiveness of cardiorespiratory training programs on overall morbidity and mortality.

Aerobic capacity and growth hormone deficiency after traumatic brain injury

CONTEXT GH deficiency occurs in approximately 20% of all individuals who suffer from a moderate to severe traumatic brain injury. OBJECTIVE This study determined whether GH deficiency secondary to traumatic brain injury had an effect on aerobic capacity. DESIGN Subjects were screened for GH deficiency by the glucagon stimulation test and performed a maximal treadmill exercise test. SETTING Patients were studied in the postacute recovery phase after traumatic brain injury. PARTICIPANTS Thirty-five individuals were studied. Groups were formed as follows: normal GH axis, greater than 8 ng/ml response (n = 12); insufficient, GH 3-8 ng/ml response (n = 11); and deficient, less than 3 ng/ml response (n = 12). INTERVENTION There was no intervention. MAIN OUTCOME MEASURE Aerobic capacity was assessed by measuring expired gases during a graded treadmill exercise test. One-way and two-way ANOVAs were carried out on all peak and submaximal cardiorespiratory variables, respectively. Appropriate post hoc comparisons followed as necessary. RESULTS Significantly higher peak oxygen consumption was found in traumatic brain injury subjects with GH normal vs. GH insufficient and deficient [26.4 +/- 6.9, 20.8 +/- 4.6, and 19.7 +/- 5.0, respectively (P < 0.05)]. Submaximal oxygen consumption was significantly higher in the GH normal group. All other variables were statistically similar. CONCLUSIONS This study shows that individuals with traumatic brain injury with normal GH secretion have below normal aerobic capacity and those patients who have GH insufficiency/deficiency are further deconditioned. Studies of GH replacement in these subjects should be conducted to assess whether GH therapy can improve cardiorespiratory fitness and prevent secondary disability.

Effect of recombinant growth hormone replacement in a growth hormone deficient subject recovering from mild traumatic brain injury: A case report.

Objective: To assess the effects of growth hormone (GH) replacement in an individual who sustained mild traumatic brain injury (mTBI) as an adult and was found to have GH deficiency by glucagon stimulation testing. Participant: A 43-year old woman who sustained a mild TBI at age 37 years. She was 6.8 years post-injury when she began supplementation. Intervention: Recombinant human GH (rhGH) subcutaneously per day for 1 year. Main outcome measures: Single fibre muscle function was evaluated from muscle biopsies. Body composition, muscle strength and peak aerobic capacity were also measured. In addition, neuropsychological tests of memory, processing speed and motor dexterity and speed, as well as a self-report depression inventory were administered. All assessments were performed at baseline and after 6 and 12 months of rhGH replacement therapy. Results: Single muscle fibre changes were greatest at 6 months. Body composition showed continuous improvement. Muscle strength improved for knee extension. Peak oxygen consumption increased at 6 months and total work and ventilatory equivalents continued to improve at 12 months. Significant improvements in neuropsychological test performance were not found, with the exception of performance on a test of motor dexterity and speed. Conclusion: rhGH replacement in a subject with GH deficiency after mild TBI improves muscle force production, body composition and aerobic capacity. Reliable improvements on tests of cognition were not found in this subject.

Responsiveness and Validity of the Six-Minute Walk Test in Individuals With Traumatic Brain Injury

Background A simple test of aerobic fitness for patients with traumatic brain injury (TBI) that is valid, reliable, and responsive to change is needed to provide clinicians a functional measure of cardiorespiratory capacity. Objective The purpose of this study was to examine the validity and responsiveness to change of the Six-Minute Walk Test (6MWT) in individuals with TBI. Design A cohort, pretest-posttest, comparison study was conducted. Methods Twenty-one patients performed the 6MWT upon admission to and prior to discharge from a postacute rehabilitation facility. Heart rate and distance traveled were recorded. A physiologic cost index (PCI) (beats per meter) was calculated based on steady-state heart rate. At discharge, all participants were able to perform a graded treadmill exercise test to exhaustion during which peak oxygen consumption (V̇o2) was measured. Results Between admission and discharge, mean total distance increased from 342.6 m (SD=127.0) to 408.9 m (SD=124.2), and work increased from 27,185 kg·m (SD=10,528) to 34,114 kg·m (SD=12,057). The effect size indexes were 1.10 and 1.12 for distance and work, respectively. Correlations (r) between the discharge peak V̇o2 and the discharge 6MWT distance, PCI, and work were .58, −.61, and .47, respectively. Limitations Stratification by gait speed may have improved responsiveness, especially for the slow ambulators. Conclusions All measures correlated well with peak V̇o2, establishing an acceptable level of criterion-related (concurrent) validity. The addition of heart rate and calculating the PCI was only slightly better at predicting peak V̇o2, albeit nonsignificant, than a simple measure of total distance. The 6MWT provides a good estimate of peak aerobic capacity, and some measures are more responsive to change than others in patients recovering from TBI.

Reliability of graded exercise testing after traumatic brain injury: submaximal and peak responses.

Mossberg KA, Greene BP: Reliability of graded exercise testing after traumatic brain injury: Submaximal and peak responses. Am J Phys Med Rehabil 2005;84:492–500. Objective:To assess the reliability of the submaximal and peak responses to a treadmill graded exercise test in individuals recovering from traumatic brain injury. Design:A total of 15 individuals (11 men, 4 women; 28.5 ± 9.2 yrs) with moderate to severe traumatic brain injury admitted into a postacute residential treatment center 10 ± 7 mos after injury performed two treadmill graded exercise tests separated by 4–8 days. Heart rate, oxygen consumption (in milliliters per minute per kilogram), minute ventilation (in liters per minute), and respiratory exchange ratio (carbon dioxide output/oxygen consumption) were continuously monitored at 1-min intervals. Submaximal and peak values were analyzed for absolute level of agreement using the intraclass correlation coefficient. Results:The submaximal intraclass correlation coefficient values for all variables between minutes 3 and 7 ranged from 0.80 to 0.93. Submaximal intraclass correlation coefficients before and in the subsequent minutes were less than optimal for heart rate and minute ventilation. Lower intensity workloads elicited slightly better agreement than higher intensity workloads. The peak response intraclass correlation coefficients ranged from 0.77 (heart rate) to 0.92 (oxygen consumption). Conclusion:Despite the presence of other co-morbidities, subjects recovering from traumatic brain injury provided consistent individual responses, allowing for reliable assessments of cardiorespiratory conditioning programs. Assessments of ambulatory efficiency, endurance, and aerobic fitness adaptations as a result of treatment for persons with traumatic brain injury should include analyses of submaximal responses to graded exercise.

Ambulatory efficiency in persons with acquired brain injury after a rehabilitation intervention.

Objective : The purpose was to assess changes in cardiorespiratory responses to treadmill ambulation in a sample of patients with acquired brain injury. Research design : A repeated measures, pre-test post-test design examined differences between submaximal and peak responses at admission and discharge. Methods and procedures : Forty individuals (29 male, 11 female) were studied. Subjects performed an ambulatory treadmill test during which heart rate (EKG) and oxygen consumption (VO2) were monitored continuously. Total ambulation time (TAT) was also recorded. Results : TAT increased from 10.3 (SD 3.1) minutes to 13.6 (SD 3.5) minutes (p < 0.01). Peak HR did not change (168 (SD 20) bpm vs. 167 (SD 21 bpm)) nor did peak VO2 (23.5 (SD 6.6)ml/min/kg vs. 24.3 (SD 6.4)ml/min/kg; p = 0.09). However, both sub-maximal HR and VO2 decreased (p < 0.05) between 2-12 minutes when most subjects were still capable of ambulating. Conclusions : The results suggest an improvement in both aerobic capacity and movement efficiency. Further controlled studies will be necessary to distinguish between cardiorespiratory and neuromuscular adaptations. The changes observed should allow for greater community participation and functional independence after discharge.

Relationships between the Quality of Life Questionnaire (QLQ) and the SF-36 among young adults burned as children

OBJECTIVE To examine the relationship between two measures that can be used to examine quality life among pediatric burn survivors. DESIGN Prospective, correlational study. SETTING Acute and rehabilitation pediatric burn care facility. PARTICIPANTS Eighty young adult survivors of pediatric burns, who were 18-28 years of age, with burns of 30% or greater, and were at least 2 years after burn. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The SF-36 and the Quality of Life Questionnaire (QLQ) were used to assess participants self-reported general health and long-term adjustment. RESULTS Significant correlations (p< or =0.001) were found between the total quality of life score of the QLQ and the mental component scale of the SF-36. However, no significant correlations were found between the total quality of life score of the QLQ and the SF-36 physical component scale. CONCLUSIONS Approximately 100,000 children are treated for burns annually, with a high percentage surviving, creating a challenge for health care professionals who need to prepare burn survivors with their psychosocial and physical well-being as adults. This study found that the SF-36 and QLQ are measuring somewhat different aspects of psychosocial and physical adjustment. It is recommended that both tools could be useful to the burn practitioner in assessing quality of life.