F. Ginatempo

Exploring brainstem function in multiple sclerosis by combining brainstem reflexes, evoked potentials, clinical and MRI investigations

OBJECTIVE To investigate vestibulo-masseteric (VMR), acoustic-masseteric (AMR), vestibulo-collic (VCR) and trigemino-collic (TCR) reflexes in patients with multiple sclerosis (MS); to relate abnormalities of brainstem reflexes (BSRs) to multimodal evoked potentials (EPs), clinical and Magnetic Resonance Imaging (MRI) findings. METHODS Click-evoked VMR, AMR and VCR were recorded from active masseter and sternocleidomastoid muscles, respectively; TCR was recorded from active sternocleidomastoid muscles, following electrical stimulation of the infraorbital nerve. EPs and MRI were performed with standard techniques. RESULTS Frequencies of abnormal BSRs were: VMR 62.1%, AMR 55.1%, VCR 25.9%, TCR 58.6%. Brainstem dysfunction was identified by these tests, combined into a four-reflex battery, in 86.9% of cases, by EPs in 82.7%, MRI in 71.7% and clinical examination in 37.7% of cases. The sensitivity of paired BSRs/EPs (93.3%) was significantly higher than combined MRI/clinical testing (70%) in patients with disease duration ⩽6.4years. BSR alterations significantly correlated with clinical, EP and MRI findings. CONCLUSIONS The four-BSR battery effectively increases the performance of standard EPs in early detection of brainstem impairment, otherwise undetected by clinical examination and neuroimaging. SIGNIFICANCE Multiple BSR assessment usefully supplements conventional testing and monitoring of brainstem function in MS, especially in newly diagnosed patients.

A comprehensive assessment of the cross-training effect in ankle dorsiflexors of healthy subjects: A randomized controlled study

PURPOSE To investigate the cross-training effect, induced on ankle dorsiflexors (AD) by unilateral strength-training of the contralateral muscles, as transfer of peak torque (PT) and muscle work (MW) and their relative contributions to muscle performance. METHODS Thirty healthy volunteers were randomly assigned to a training or control group. The trained group sustained a 4-week maximal isokinetic training of the stronger AD at 90 and 45°/s. At both angular velocities, PT, MW and MW/PT ratio were measured from both legs at baseline and after intervention (trained group) or no-intervention (controls). The familiarization/learning-effect was calculated and subtracted by PT and MW measures to obtain their net changes. RESULTS Net PT increased in both legs (untrained: +27.5% at 90°/s and +17.9% at 45°/s; trained: +15% at 90°/s and +16.3% at 45°/s). Similarly, net MW increased in both the untrained (90°/s: +29.6%; 45°/s: +37%) and trained (90°/s: +23.4%; 45°/s: +18.3%) legs. PT and MW gains were larger in the untrained than trained AD (p<0.0005), with MW improving more than PT at 45°/s (p=0.04). The MW/PT ratio increased bilaterally only in the trained group (p<0.05), depending on the angular velocity. CONCLUSIONS The cross-training effect occurred in AD muscles in terms of both PT and MW, with MW adding valuable information to PT-analysis in describing muscle performance. Moreover, the MW/PT ratio allowed estimating the contributions of these parameters to muscle capability and may represent a novel index in isokinetic testing. The greater improvements in the untrained than trained limb raises interesting clinical implications in asymmetric conditions.

Paired neurophysiological and clinical study of the brainstem at different stages of Parkinson’s Disease

OBJECTIVE To study brainstem function in Parkinsons Disease (PD) at different stages, through a battery of vestibular-evoked myogenic potentials (VEMPs) and compare the results with scores on clinical scales assessing the presence of symptoms linked to brainstem involvement. METHODS Cervical, masseter and ocular VEMPs were recorded in patients with early PD (n=14, disease duration 1.42±0.7years), advanced PD (n=19, disease duration 7.26±2.9years) and in 27 age-matched controls. In PD, the following clinical scales were administered: Mini-BESTest, REM sleep Behavior Disorder Screening Questionnaire (RBD-SQ), PD Sleep Scale, Epworth Sleepiness Scale and Geriatric Depression Scale. RESULTS Rate of VEMPs alterations was higher (p<0.001) in PD than controls, but similar within PD groups. However, early and advanced PD showed a different pattern of abnormalities (p=0.02), being latency delay prevalent in the former and absence in the latter. VEMP impairment correlated directly with RBD-SQ scores in both PD cohorts and inversely with Mini-BESTest scores in advanced PD. CONCLUSIONS VEMPs displayed progressive severity of alterations at different stages of PD, with remarkable correlations with presence of postural instability and RBD. SIGNIFICANCE The combined use of VEMPs may provide interesting insights into the pathophysiological mechanisms of PD at the earliest and prodromal stage of the disease.

Effect of Contralateral Strength Training on Muscle Weakness in People With Multiple Sclerosis: Proof-of-Concept Case Series

Background The contralateral strength training (CST) effect is a transfer of muscle performance to the untrained limb following training of the contralateral side. Objective The aim of this study was to explore, in individuals with multiple sclerosis (MS) presenting marked lower limb strength asymmetry, the effectiveness of CST on management of muscle weakness of the more-affected limb following training of the less-affected limb. Design A single-subject research design was used. Methods Eight individuals with MS underwent 16 to 18 high-intensity training sessions of the less-affected ankle dorsiflexor muscles. The primary outcome measure of this single-system case series was maximal strength expressed as peak moment and maximal work. Secondary outcome measures were: Six-Minute-Walk Test, Timed “Up & Go” Test, 10-Meter Timed Walk Test, and Multiple Sclerosis Quality of Life–54 questionnaire. Results After the 6-week intervention, the contralateral more affected (untrained) limb showed a 22% to 24% increase in maximal strength. From pretest-posttest measurements, participants also performed significantly better on the clinical and functional secondary outcome measures. At the 12-week follow-up, the strength levels of the weaker untrained limb remained significantly superior to baseline levels in the majority (5 out of 8) of the outcome parameters. Limitations Considering the design used, the absence of a control group, and the sample size, these findings should be cautiously generalized and will need confirmation in a properly planned randomized controlled trial. Conclusions The present proof-of-concept study shows, for the first time, the occurrence of the CST effect on muscle performance of ankle dorsiflexor muscles in people with MS. These preliminary findings reveal new potential implications for CST as a promising rehabilitation approach to those conditions where unilateral muscle weakness does not allow or makes difficult performing conventional strength training of the weaker limb.

Ultrasound and laser as stand-alone therapies for myofascial trigger points: a randomized, double-blind, placebo-controlled study.

BACKGROUND AND PURPOSE Ultrasound (US) and low-level laser therapy (LLLT) are commonly employed for myofascial trigger points (MTP) despite lack of evidence for usage as stand-alone treatments. The aim of the study was to determine, on MTP of the upper trapezius muscle (uTM), the effects of US and LLLT per se, as delivered in accordance with the procedures reported by surveys about their usage among physiotherapists. METHODS Design was set as a double-blind, randomized, placebo-controlled study. Sixty participants with at least one active MTP in uTM (28 women and 32 men; mean age 24.5 ± 1.44 years) were recruited and randomly assigned to one out of five groups: active US (n = 12), placebo US (n = 12), active LLLT (n = 11), placebo LLLT (n = 11) and no therapy (control, n = 14). The participants and outcome assessor were blinded to the group assignment and therapy delivered. Three outcome measures were assessed at baseline, after a 2-week treatment and 12 weeks after the end of the intervention (follow-up): pressure pain threshold, subjective pain on a numerical rating scale and muscle extensibility performing a cervical lateral flexion. All subjects assigned to the intervention groups were treated five times weekly for overall 10 treatments given. Two-way ANOVA was used to compare differences before and after intervention and among groups at each time-point. RESULTS After the 2-week intervention, all groups showed pressure pain threshold, numerical rating scale and cervical lateral flexion significant improvements (p < 0.05), which were confirmed at the follow-up. When performing multiple comparisons, controls scored significantly less than both the active therapies and placebos, whereas no differences were detected between active therapies and placebos. CONCLUSIONS Ultrasound and LLLT provided significant improvements in pain and muscle extensibility, which were superior to no therapy but not to placebos, thus raising concerns about the suitability, both economically and ethically, of administering such common physical modalities as stand-alone treatments in active MTP of the uTM.

Cerebellar Theta-Burst Stimulation Impairs Memory Consolidation in Eyeblink Classical Conditioning

Associative learning of sensorimotor contingences, as it occurs in eyeblink classical conditioning (EBCC), is known to involve the cerebellum, but its mechanism remains controversial. EBCC involves a sequence of learning processes which are thought to occur in the cerebellar cortex and deep cerebellar nuclei. Recently, the extinction phase of EBCC has been shown to be modulated after one week by cerebellar continuous theta-burst stimulation (cTBS). Here, we asked whether cerebellar cTBS could affect retention and reacquisition of conditioned responses (CRs) tested immediately after conditioning. We also investigated a possible lateralized cerebellar control of EBCC by applying cTBS on both the right and left cerebellar hemispheres. Both right and left cerebellar cTBSs induced a statistically significant impairment in retention and new acquisition of conditioned responses (CRs), the disruption effect being marginally more effective when the left cerebellar hemisphere was stimulated. These data support a model in which cTBS impairs retention and reacquisition of CR in the cerebellum, possibly by interfering with the transfer of memory to the deep cerebellar nuclei.

VEMPs in central neurological disorders

http://dx.doi.org/10.1016/j.clinph.2016.01.02