Jim Jensen

Training-induced cortical plasticity compared between three tongue-training paradigms

The primary aim of this study was to investigate the effect of different training types and secondary to test gender differences on the training-related cortical plasticity induced by three different tongue-training paradigms: (1) therapeutic tongue exercises (TTE), (2) playing computer games with the tongue using the Tongue Drive System (TDS) and (3) tongue-protrusion task (TPT). Forty-eight participants were randomized into three groups with 1h of TTE, TDS, or TPT. Stimulus-response curves of motor evoked potentials (MEPs) and motor cortex mapping for tongue muscles and first dorsal interosseous (FDI) (control) were established using transcranial magnetic stimulation at three time-points: (1) before tongue-training, (2) immediately after training, (3) 1h after training. Subject-based reports of motivation, fun, pain and fatigue were evaluated on 0-10 numerical rating scales after training. The resting motor thresholds of tongue MEPs were lowered by training with TDS and TPT (P<0.011) but not by TTE (P=0.167). Tongue MEP amplitudes increased after training with TDS and TPT (P<0.030) but not with TTE (P=0.302). Men had higher MEPs than women in the TDS group (P<0.045) at all time-points. No significant effect of tongue-training on FDI MEPs was observed (P>0.335). The tongue cortical motor map areas were not significantly increased by training (P>0.142). Training with TDS was most motivating and fun (P<0.001) and TTE was rated the most painful (P<0.001). Fatigue level was not different between groups (P>0.071). These findings suggest a differential effect of tongue-training paradigms on training-induced cortical plasticity and subject-based scores of fun, motivation and pain in healthy participants.

Heart rate variability in neurorehabilitation patients with severe acquired brain injury.

Abstract Introduction: Acquired brain injury (ABI) cause neural deficits. In addition to motor and cognitive deficits, the autonomic nervous system may be affected. This has been shown for neurorehabilitation patients with traumatic brain injury (TBI) by means of reduced heart rate variability (HRV). It was hypothesized that patient groups with other ABI aetiology (mainly stroke, subarachnoid haemorrhage and anoxia) would also present reduced HRV. Methods: Patients consecutively admitted and severely ABI injured were considered for HRV measurements. HRV was extracted as a mean of four 5-minute ECG recordings at 6 pm, 10 pm, 2 am and 6 am the following day (scheduled resting periods). One 5-minute HRV recording from a sex- and age-matched group of healthy volunteers constituted control data. Standard deviation of normal-to-normal intervals (SDNN) and low frequency (LF) were primary HRV variables. Results: Of 71 admitted patients, HRV was extracted from 49 patients. Patient SDNN and LF were reduced compared to controls (SDNN: 13 ms (CI = [10.8; 15.3]) vs 40.3 ms (CI = [36.6; 44.2]), p < 0.0001; LF: 29.4 ms2 (CI = [19.8; 43.7]) vs 518 ms2 (CI = [419; 639]), p < 0.0001). HRV appeared identical across ABI aetiology. Conclusion: It was found that HRV was considerably reduced in an heterogenic ABI patient group admitted for neurorehabilitation.

Association between the sensory-motor nervous system and the autonomic nervous system in neurorehabilitation patients with severe acquired brain injury.

Abstract Introduction: The relation between motor and cognitive function and autonomic nervous system (ANS) function during neurorehabilitation following acquired brain injury (ABI) has only been investigated sporadically. In the present study, it was hypothesized that clinical measures in severely injured patients would relate to heart rate variability (HRV), a measure of autonomic function. Methods: HRV measurements were initially performed on 49 patients (enrolled in a previous study) and follow-up (> 28 days) HRV measurements were performed. Standard deviation of normal-to-normal intervals (SDNN) and low frequency (LF) were extracted and these HRV variables were related to the clinical measures, Early Functional Ability (EFA) and Functional Independence Measure (FIM). Associations between HRV and clinical measures were analysed on admission data (only EFA), at follow-up and for the longitudinal change in measures. Results: Follow-up HRV was extracted from 19 patients. SDNN and LF were significantly correlated (p < 0.05) to the EFA and FIM at follow-up, but not at admission. SDNN and LF changes were significantly correlated to EFA changes, but not FIM changes. Admission SDNN and LF were unable to provide prognostic information for the EFA and FIM at follow-up. Conclusion: HRV and its change during neurorehabilitation were associated to EFA and EFA changes over time. Further studies are required to clarify a number of limitations arising from this observational study.

Effect of transcranial direct current stimulation on neuroplasticity in corticomotor pathways of the tongue muscles

The aim of this study is to investigate effects of transcranial direct current stimulation (tDCS) on neuroplasticity in corticomotor pathways related to tongue muscles evoked by a training task using the tongue drive system (TDS). Using a crossover design, 13 healthy participants completed two sessions of tDCS while performing 30 min of TDS training. Sessions were spaced at least 2 weeks apart and participants randomly received anodal and sham tDCS stimulation in the first session and the other condition in the second session. Single and paired pulse transcranial magnetic stimulation was used to elicit motor evoked potentials (MEPs) of the tongue at three time-points: before, immediately after and 30 min after training. Participant-based reports of fun, pain, fatigue and motivation, level of difficulty and effort were evaluated on numerical rating scales. There was no consistent significant effect of anodal and sham stimulation on single or paired pulse stimulation MEP amplitude immediately or 30 min after TDS training. Irrespective of tDCS type, training with TDS induced cortical plasticity in terms of increased MEP amplitudes for higher stimulus intensities after 30 min compared with before and immediately after training. Participant-based reports revealed no significant difference between tDCS conditions for level of fun, fatigue, motivation, difficulty and level of effort but a significant increase in pain in the anodal condition, although pain level was low for both conditions. In conclusion, tongue MEP amplitudes appear to be sensitive to training with the tongue using TDS; however, anodal tDCS does not have an impact on training-evoked neuroplasticity of tongue corticomotor pathways.

Influence of External Subglottic Air Flow on Dysphagic Tracheotomized Patients With Severe Brain Injury: Preliminary Findings

Objective: The aim of this study was to determine if external subglottic air flow (ESAF) influences swallowing frequency in severely dysphagic tracheotomized patients with brain injury. Methods: Ten patients were recruited at the neurological intensive care unit. The ESAF intervention was provided through the standard cuffed suction aid tracheotomy tube, which primarily is used to suction residual secretion volume from the subglottic area. Sessions were 150 minutes, and ESAF was provided at 60-65, 90-95, and 120-125 minutes at 3 L/min. Outcome measures included swallowing frequency (swallows/5 min) at 0-5 minutes (pre-baseline), 25-30 and 55-60 minutes (baseline/control), and 85-90, 115-120, and 145-150 minutes (postintervention). The residual secretion volume (ml) from the subglottic area was collected using a syringe at 0 minutes (pre-baseline), 30 and 60 minutes (baseline/ control), and at 90, 120, and 150 minutes (postintervention). Results: The mean (±SEM) swallowing frequency (swallows/5 min) increased from 0.60 ± 0.30 to 2.10 ± 0.70 during the ESAF intervention (P < .001). The mean (±SEM) residual secretion volume reduced from 3.10 ± 0.31 ml to 0.50 ± 0.30 ml after the ESAF intervention (P < .001). Conclusion: The increase in swallowing frequency and reduction in residual secretion volume may indicate that ESAF influences swallowing parameters in patients with tracheotomy tubes.

Referral decision support in patients with subacute brain injury: evaluation of the Rehabilitation Complexity Scale - Extended.

Abstract Purpose: To test if the Rehabilitation Complexity Scale Extended (RCS-E) can be used as decision support for patient referral to primary rehabilitation as either complex specialized services (CSS) or district specialist services (DSS). Method: Two independent expert teams analyzed medical records on 299 consecutive patients admitted for CSS or DSS rehabilitation. One team provided a golden standard for the patient referrals, and the other team provided RCS-E scores. Models for predicting referrals from RCS-E scores were developed on data for 149 patients and tested on the remaining 150 patients. Results: The optimal RCS-E sum score threshold for referral prediction was 11, predicting the golden standard for patient referral with sensitivity 88%, specificity 78% and correct classification rate 81%. Improved referral prediction performance was achieved by using RCS-E item-wise score thresholds (sensitivity 81%, specificity 89%, correct classification rate 87%). The RCS-E sum score range for patients referred CSS and DSS by the item-wise model was, respectively, 0–12 and 2–22 suggesting strong non-linear interaction of the RCS-E items. Conclusions: We found excellent referral decision support in the RCS-E and the item specific threshold model, when patients with acquired brain injury are to be referred to CSS or DSS as their primary rehabilitation. Implications for Rehabilitation Efficient rehabilitation after acquired brain injury requires rehabilitation settings that meet patient needs. Validated tools for referral decision support make the process more transparent. Patient rehabilitation complexity can be stratified by the RCS-E with high sensitivity, specificity and predictive value of positive test. RCS-E is an excellent tool for referral decision support.

Tongue Motor Training – Behavioral and Neurophysiological Aspects

The purpose of this overall project was to elucidate the influence of different tongue training paradigms on behavioral motor learning and cortical plasticity.