Methods for automated delineation and assessment of EMG responses evoked by peripheral nerve stimulation in diagnostic and closed-loop therapeutic applications.

Objective.Surface electromyography measurements of the Hoffmann (H-) reflex are essential in a wide range of neuroscientific and clinical applications. One promising emerging therapeutic application is H-reflex operant conditioning, whereby a person is trained to modulate the H-reflex, with generalized beneficial effects on sensorimotor function in chronic neuromuscular disorders. Both traditional diagnostic and novel realtime therapeutic applications rely on accurate definitions of the H-reflex and M-wave temporal bounds, which currently depend on expert case-by-case judgment. The current study automates such judgments.Approach.Our novel wavelet-based algorithm automatically determines temporal extent and amplitude of the human soleus H-reflex and M-wave. In each of 20 participants, the algorithm was trained on data from a preliminary 3 or 4 min recruitment-curve measurement. Output was evaluated on parametric fits to subsequent sessions' recruitment curves (92 curves across all participants) and on the conditioning protocol's subsequent baseline trials (∼1200 per participant) performed nearHmax. Results were compared against the original temporal bounds estimated at the time, and against retrospective estimates made by an expert 6 years later.Main results.Automatic bounds agreed well with manual estimates: 95% lay within ±2.5 ms. The resulting H-reflex magnitude estimates showed excellent agreement (97.5% average across participants) between automatic and retrospective bounds regarding which trials would be considered successful for operant conditioning. Recruitment-curve parameters also agreed well between automatic and manual methods: 95% of the automatic estimates of the current required to elicitHmaxfell within±1.4%of the retrospective estimate; for the 'threshold' current that produced an M-wave 10% of maximum, this value was±3.5%.Significance.Such dependable automation of M-wave and H-reflex definition should make both established and emerging H-reflex protocols considerably less vulnerable to inter-personnel variability and human error, increasing translational potential.

TheraBracelet Stimulation During Task-Practice Therapy to Improve Upper Extremity Function After Stroke: A Pilot Randomized Controlled Study.

BACKGROUND: Peripheral sensory stimulation has been used in conjunction with upper extremity movement therapy to increase therapy-induced motor gains in patients with stroke. The limitation is that existing sensory stimulation methods typically interfere with natural hand tasks and thus are administered prior to therapy, requiring patients' time commitment. To address this limitation, we developed TheraBracelet. This novel stimulation method provides subthreshold (ie, imperceptible) vibratory stimulation to the wrist and can be used during hand tasks/therapy without interfering with natural hand tasks. OBJECTIVE: The objective was to determine the feasibility of using TheraBracelet during therapy to augment motor recovery after stroke. DESIGN: The design was a triple-blinded pilot randomized controlled trial. METHODS: Twelve chronic stroke survivors were assigned to the treatment or control group. All participants completed 2-hour task practice therapy sessions thrice weekly for 2 weeks. Both groups wore a small vibrator on the paretic wrist, which was turned on to provide TheraBracelet stimulation for the treatment group and turned off for the control group to provide sham stimulation. Outcome measures (Box and Block Test [BBT] and Wolf Motor Function Test [WMFT]) were obtained at baseline, 6 days after therapy, and at follow-up 19 days after therapy. RESULTS: The intervention was feasible with no adverse events. The treatment group significantly improved their BBT scores after therapy and at follow-up compared with baseline, whereas the control group did not. For WMFT, the group × time interaction was short of achieving significance. Large effect sizes were obtained (BBT d = 1.43, WMFT d = 0.87). No indication of desensitization to TheraBracelet stimulation was observed. LIMITATIONS: The limitation was a small sample size. CONCLUSIONS: TheraBracelet could be a promising therapy adjuvant for upper extremity recovery after stroke.

Safety and tolerability of transcranial direct current stimulation to stroke patients - A phase I current escalation study.

BACKGROUND AND OBJECTIVE: A prior meta-analysis revealed that higher doses of transcranial direct current stimulation (tDCS) have a better post-stroke upper-extremity motor recovery. While this finding suggests that currents greater than the typically used 2 mA may be more efficacious, the safety and tolerability of higher currents have not been assessed in stroke patients. We aim to assess the safety and tolerability of single session of up to 4 mA in stroke patients. METHODS: We adapted a traditional 3 + 3 study design with a current escalation schedule of 1¼2¼2.5¼3¼3.5¼4 mA for this tDCS safety study. We administered one 30-min session of bihemispheric montage tDCS and simultaneous customary occupational therapy to patients with first-ever ischemic stroke. We assessed safety with pre-defined stopping rules and investigated tolerability through a questionnaire. Additionally, we monitored body resistance and skin temperature in real-time at the electrode contact site. RESULTS: Eighteen patients completed the study. The current was escalated to 4 mA without meeting the pre-defined stopping rules or causing any major safety concern. 50% of patients experienced transient skin redness without injury. No rise in temperature (range 26°C-35 °C) was noted and skin barrier function remained intact (i.e. body resistance >1 kΩ). CONCLUSION: Our phase I safety study supports that single session of bihemispheric tDCS with current up to 4 mA is safe and tolerable in stroke patients. A phase II study to further test the safety and preliminary efficacy with multi-session tDCS at 4 mA (as compared with lower current and sham stimulation) is a logical next step. ClinicalTrials.gov Identifier: NCT02763826.

Matching Task Difficulty to Patient Ability During Task Practice Improves Upper Extremity Motor Skill After Stroke: A Proof-of-Concept Study.

OBJECTIVE: To test the feasibility of the Fugl-Meyer Assessment of the Upper Extremity "keyform," derived from Rasch analysis, as a method for systematically planning and progressing rehabilitation. DESIGN: Feasibility study, single group design. SETTING: University rehabilitation research laboratory. PARTICIPANTS: Participants (N=10; mean age, 59.70±9.96y; 24.1±30.54mo poststroke) with ischemic or hemorrhagic stroke >3 months prior, voluntarily shoulder flexion ≥30°, and simultaneous elbow extension ≥20°. INTERVENTIONS: The keyform method defined initial rehabilitation targets (goals) and progressed the rehabilitation program after every third session. Targets were repetitively practiced within the context of client-selected functional tasks not in isolation. MAIN OUTCOME MEASURES: Feasibility was defined by subject's pain or fatigue, upper extremity motor function (Wolf Motor Function Test), and movement patterns (kinematics). Assessments were administered pre- and posttreatment and compared using paired t tests. Task-difficulty and patient-ability measures were calculated using Rasch analysis and compared using paired t tests (P<.05). RESULTS: Ten participants completed 9 sessions, 200 movement repetitions per session in <2 hours without pain or fatigue. Participants gained upper extremity motor function (Wolf Motor Function Test: pretreatment, 22.23±24.26s; posttreatment, 15.46±22.12s; P=.01), improved shoulder-elbow coordination (index of curvature: pretreatment, 1.30±0.15; posttreatment, 1.21±0.11; P=.01), and exhibited reduced trunk compensatory movement (trunk displacement: pretreatment, 133.97±74.15mm; posttreatment, 108.08±64.73mm; P=.02). Task-difficulty and patient-ability measures were not statistically different throughout the program (person-ability measures of 1.01±0.05, 1.64±0.45, and 2.22±0.65 logits and item-difficulty measures of 0.93±0.37, 1.70±0.20, and 2.06±0.24 logits at the 3 testing time points, respectively; P>.05). CONCLUSIONS: The Fugl-Meyer Assessment of the Upper Extremity keyform is a feasible method to ensure that the difficulty of tasks practiced were well matched to initial and evolving levels of upper extremity motor ability.