Charlotte Yates

Restoration of frequency-dependent depression of the H-reflex by passive exercise in spinal rats

Study design:Hyper-reflexia, measured as a decrease of low frequency-dependent depression of the H-reflex, is known to occur in both humans and animals after spinal cord injury (SCI). Previous studies have shown that passive exercise for 3 months could be used to restore low frequency-dependent depression of the H-reflex after SCI.Objective:To determine the effects of various periods of time on the ability of passive exercise to restore low frequency-dependent depression of the H-reflex.Setting:Spinal Cord Injury Mobilization Program of the Center for Translational Neuroscience, the research arm of the Jackson T Stephens Spine & Neuroscience Institute, Little Rock, AR, USA.Methods:Adult rats underwent complete spinal cord transection at the T10 level. The hindlimbs were passively exercised in different groups of rats for 1 h/day, 5 days/week for 15, 30, 45, 60, or 90 days, and low frequency-dependent depression of the H-reflex was tested.Results:Statistically significant low frequency-dependent depression of the H-reflex was evident by 30 days of exercise, although numerical reductions were seen even at 15 days. There was a linear decrease in low frequency-dependent depression of the H-reflex with duration of passive exercise.Conclusions:Passive exercise can restore frequency-dependent depression of spinal reflexes in a time-dependent manner if used following complete spinal transection.Sponsorship:Supported by USPHS award RR020146 and the Arkansas Biosciences Institute.

Use of a motorized bicycle exercise trainer to normalize frequency-dependent habituation of the H-reflex in spinal cord injury.

Abstract Background/Objectives: Spasticity in patients with spinal cord injury (SCI) is difficult to manage. Exercise and stretching is advocated as a management tool, butthese activities are difficult to perform for mostpatients as a result of multiple barriers. This report shows the effect of passive range-of-motion exercise ina walking-like pattern on frequency-dependent habituation of the H-reflex in the lower extremities of anindividual with spastic tetraplegia due to SCI. Methods: The participant, a man with a chronic ASIA B C7 SCI due to a gunshot wound, used a motorized bicycle exercise trainer (MBET) developed at the Jackson T. Stephens Spine & Neurosciences Institute at theUniversity of Arkansas for Medical Sciencesthat could be operated from the individuals wheelchair. He usedthe MBET for 1 hour, 5 days a week, for 13 weeks. H-reflexhabituation was tested at the beginningof thestudy and then periodically over the course of 1 7 weeks,including 4 weeks after exercise had ceased. Results: Significant habituation of the H-reflex was evident beginning atthe 1Oth week of training. The habituation in the H-reflex reached a normal level at 5- and 10-Hz frequencies at 12 weeks. Subjective assessment of spasticity indicated that it was significantly reduced. The H-reflex amplitude was maintained at normal levels during the remaining week of the course of exercise and for 2 additional weeks after exerciseceased.The H-reflex habituation, however, returned to near baseline when reassessed at week 17,4 weeks after the exercise program had concluded. Subjective assessment indicated thatspasticity also had returned to pretraining levels. Conclusions: Habituation of the H-reflex, and perhaps spasticity, can be managed by aroutine passive range-of-motion exercise program using a MBET, but the exercise program may need to be continuous. The benefit of reduced medication for spasticity and possibly improved quality of lifecould be a motivating factor for an individual with SCI and spasticity to continue the program. Because of thelow complexity ofthe program, ease of use, and small size, this system could be inexpensive and could be used by an individual in the home. Ongoing studies will determine the minimum amount of MBET training required formaintaining long-term H-reflex habituation.

Serial casting vs combined intervention with botulinum toxin A and serial casting in the treatment of spastic equinus in children.

Purpose Serial casting has been an effective tool used by physical therapists to increase ankle dorsiflexion range of motion and improve functional gait. The purpose of this retrospective study was to determine whether injection with botulinum toxin type A (BtA) before serial casting vs serial casting alone was associated with any changes in (1) the number of weeks necessary to reach the desired dorsiflexion range of motion and (2) the number of degrees of dorsiflexion range of motion gained per week of casting. Method Data were obtained through review of records maintained on patients undergoing serial casting. Thirty subjects comprised the two groups of 15 patients each. One group had received BtA before serial casting while the other group had received no BtA before serial casting. Data were analyzed using two t tests to determine whether there were significant differences, and the appropriate statistical adjustment (Bonferroni) was applied. Results Fewer weeks were required to reach the goal of 15 to 20 degrees of ankle dorsiflexion (or plateau) for the group receiving BtA than for the group that did not receive BtA. Results also indicated that the group receiving BtA had a significantly greater increase in range of motion per week than the group that received no BtA. Conclusions Using serial casting in conjunction with BtA may achieve range of motion goals in less time than serial casting alone.

The effects of passive exercise therapy initiated prior to or after the development of hyperreflexia following spinal transection

Hyperreflexia develops after spinal cord injury (SCI) in the human and in the spinal cord transected animal, and can be measured by the loss of low frequency-dependent depression of the H-reflex. Previous studies demonstrated normalization of low frequency-dependent depression of the H-reflex using passive exercise when initiated prior to the development of hyperreflexia. We examined the effects of passive exercise prior to compared to after the development of hyperreflexia in the transected rat. Adult female rats underwent complete transection (Tx) at T10. Frequency-dependence of the H-reflex was tested following passive exercise for 30 days, initiated prior to hyperreflexia in one group compared to initiation after hyperreflexia became established, and compared to intact and untreated Tx groups. An additional Tx group completed 60 days of exercise initiated after hyperreflexia was established. Lumbar enlargement tissue was harvested for western blot to compare Connexin-36 protein levels in control vs Tx animals vs Tx animals that were passively exercised. No differences in whole tissue were evident, although regional differences may still be present in Connexin-36 levels. Statistically significant decreases in low frequency-dependent depression of the H-reflex were observed following 30 days of exercise initiated prior to the onset of hyperreflexia, and also after 60 days of exercise when initiated after hyperreflexia had been established, compared with Tx only animals. We concluded that modulation of spinal circuitry by passive exercise took place when initiated before and after the onset of hyperreflexia, but different durations of exercise were required.

Does daily kangaroo care provide sustained pain and stress relief in preterm infants

OBJECTIVES 1. Determine whether stress in preterm infants, measured with salivary cortisol, decreases after five days of Kangaroo Care (KC) compared to five days of Standard Care (SC). 2. To determine whether kangaroo care provides sustainable pain relief beyond the period of skin-to-skin holding. STUDY DESIGN Preterm infants (n = 38) born at 27-30 weeks gestational age were randomized to either the KC or the SC group and received the allocated intervention starting on day of life (DOL) five and continuing for five days. Salivary cortisol was collected on DOL five and again on DOL ten. Differences were analyzed using repeated measures ANOVA and t tests. Pain during nasal suctioning over five days was assessed using the Premature Infant Pain Profile (PIPP). RESULT 1. Adequate saliva samples for salivary cortisol were collected for 13 KC infants and 11 SC infants. There was no main effect of group (p = 0.49), but there was a significant main effect of age (DOL five versus DOL ten), with salivary cortisol levels decreasing in both groups (p = 0.02). 2. Pain scores for both groups (n = 38) indicted mild to moderate pain during suctioning, with no significant difference in pain scores between groups. CONCLUSION 1. KC did not affect salivary cortisol levels in preterm neonates, but levels in both the KC and SC groups decreased over time from DOL five to ten. Salivary cortisol may vary with age of infant. 2. Infants experience pain during routine suctioning and may require pain management.

Effects of daily kangaroo care on cardiorespiratory parameters in preterm infants

BACKGROUND/AIMS Kangaroo care (KC) has possible benefits for promoting physiological stability and positive developmental outcomes in preterm infants. The purpose of this study was to compare bradycardia and oxygen desaturation events in preterm infants in standard incubator care versus KC. METHODS Thirty-eight infants 27 to 30 weeks gestational age were randomly assigned to 2 hours of KC daily between days of life 5 to 10 or to standard incubator care. Infants were monitored for bradycardia (heart rate <80) or oxygen desaturation (<80%). Analysis of hourly events was based on three sets of data: standard care group 24 hours daily, KC group during incubator time 22 hours daily, and KC group during holding time 2 hours daily. RESULTS The KC group had fewer bradycardia events per hour while being held compared to time spent in an incubator (p = 0.048). The KC group also had significantly fewer oxygen desaturation events while being held than while in the incubator (p = 0.017) and significantly fewer desaturation events than infants in standard care (p = 0.02). CONCLUSION KC reduces bradycardia and oxygen desaturation events in preterm infants, providing physiological stability and possible benefits for neurodevelopmental outcomes.

Wind-up of stretch reflexes as a measure of spasticity in chronic spinalized rats: The effects of passive exercise and modafinil

Spasticity is a common disorder following spinal cord injury that can impair function and quality of life. While a number of mechanisms are thought to play a role in spasticity, the role of motoneuron persistent inward currents (PICs) is emerging as pivotal. The presence of PICs can be evidenced by temporal summation or wind-up of reflex responses to brief afferent inputs. In this study, a combined neurophysiological and novel biomechanical approach was used to assess the effects of passive exercise and modafinil administration on hyper-reflexia and spasticity following complete T-10 transection in the rat. Animals were divided into 3 groups (n=8) and provided daily passive cycling exercise, oral modafinil, or no intervention. After 6weeks, animals were tested for wind-up of the stretch reflex (SR) during repeated dorsiflexion stretches of the ankle. H-reflexes were tested in a subset of animals. Both torque and gastrocnemius electromyography showed evidence of SR wind-up in the transection only group that was significantly different from both treatment groups (p<0.05). H-reflex frequency dependent depression was also restored to normal levels in both treatment groups. The results provide support for the use of passive cycling exercise and modafinil in the treatment of spasticity and provide insight into the possible contribution of PICs.

Modafinil normalized hyperreflexia after spinal transection in adult rats

Study Design:Hyperreflexia occurs after spinal cord injury and can be assessed by measuring low frequency-dependent depression of the H-reflex in the anesthetized animal.Objective:To determine the effects of Modafinil (MOD), given orally, following a complete SCI compared with animals receiving MBET and transected untreated animals and examine if changes exist in Connexin 36 (Cx-36) protein levels in the lumbar enlargement of animals for the groups described.Setting:Center for Translational Neuroscience, Little Rock, AR, USA.Methods:Adult female rats underwent complete transection (Tx) at T10 level. H-reflex testing was performed 30 days following Tx in one group, and after initiation of treatment with MOD in another group, and after MBET training in the third group. The Lumbar enlargement tissue was harvested and western blots were performed after immunoprecipitation techniques to compare Cx-36 protein levels.Results:Statistically significant decreases in low frequency-dependent depression of the H-reflex were observed in animals that received MOD and those that were treated with MBET compared with the Tx, untreated group. Statistically significant changes in Cx-36 protein levels were not observed in animals treated with MOD compared with Tx, untreated animals.Conclusion:Normalization of the loss of low frequency -dependent depression of the H-reflex was demonstrated in the group receiving MOD and the group receiving MBET compared with the Tx, untreated group. Further work is needed to examine if Cx-36 protein changes occur in specific subregions of the spinal cord.Sponsors:NIH-NCRR Grant P20 RR020146 to the CTN and NINDS P30 NS047546

The effects of massage therapy to induce sleep in infants born preterm.

Purpose: The aim of this study was to determine whether massage therapy can be used as an adjunct intervention to induce sleep in infants born preterm. Methods: Thirty infants born at a minimum of 28 weeks gestational age, who were at the time of the study between 32 and 48 weeks adjusted gestational age, were randomly assigned to receive massage therapy on 1 day and not receive massage on an alternate day. The Motionlogger Micro Sleep Watch Actigraph recorded lower extremity activity on the morning of each day. Results: No significant difference was found between groups for sleep efficiency (P = .13) during the time period evaluated. Groups differed significantly during the time period after the massage ended with more infants sleeping on the nonmassage day (&khgr;2 = 4.9802, P = .026). Conclusions: Massage is well tolerated in infants born preterm and infants do not fall asleep faster after massage than without massage.

Novel mechanism for hyper-reflexia and spasticity

We established that hyperreflexia is delayed after spinal transection in the adult rat and that passive exercise could normalize low frequency-dependent depression of the H-reflex. We were also able to show that such passive exercise will normalize hyperreflexia in patients with spinal cord injury (SCI). Recent results demonstrate that spinal transection results in changes in the neuronal gap junction protein connexin 36 below the level of the lesion. Moreover, a drug known to increase electrical coupling was found to normalize hyperreflexia in the absence of passive exercise, suggesting that changes in electrical coupling may be involved in hyperreflexia. We also present results showing that a measure of spasticity, the stretch reflex, is rendered abnormal by transection and normalized by the same drug. These data suggest that electrical coupling may be dysregulated in SCI, leading to some of the symptoms observed. A novel therapy for hyperreflexia and spasticity may require modulation of electrical coupling.