Signal features of surface electromyography in advanced Parkinson’s disease during different settings of deep brain stimulation

Abstract

h i g h l i g h t sEfficacy of deep brain stimulation (DBS) treatment was quantified here by using surface EMG and acceleration measurements. EMG signal features differed between different DBS settings for biceps brachii muscles. EMG features pointed to previously defined optimal settings in most of patients. a b s t r a c tObjective: Electromyography (EMG) and acceleration (ACC) measurements are potential methods for quantifying efficacy of deep brain stimulation (DBS) treatment in Parkinson's disease (PD). The treatment efficacy depends on the settings of DBS parameters (pulse amplitude, frequency and width). This study quantified, if EMG and ACC signal features differ between different DBS settings and if DBS effect is unequal between different muscles. Methods: EMGs were measured from biceps brachii (BB) and tibialis anterior (TA) muscles of 13 PD patients. ACCs were measured from wrists. Measurements were performed during seven different settings of DBS and analyzed using methods based on spectral analysis, signal morphology and nonlinear dynamics. Results:The results showed significant within-subject differences in the EMG signal kurtosis, correlation dimension, recurrence rate and EMG-ACC coherence between different DBS settings for BB but not for TA muscles. Correlations between EMG feature values and clinical rest tremor and rigidity scores were weak but significant. Conclusions: Surface EMG features differed between different DBS settings and DBS effect was unequal between upper and lower limb muscles. Significance: EMG changes pointed to previously defined optimal settings in most of patients, which should be quantified even more deeply in the upcoming studies.

Alternate Subthalamic Nucleus Deep Brain Stimulation Parameters to Manage Motor Symptoms of Parkinson's Disease: Systematic Review and Meta‐analysis

“…In contrast, a separate study indicated that lowering amplitude by 50% for the hemisphere corresponding to the patients' legs that exhibited the longer step length (i.e., compared with the contralateral limb), significantly reduced the frequency and duration of freezing episodes without introducing any measurable changes in velocity, stride length, or cadence . However, these improvements in freezing of gait came at the cost of a re‐emergence of other PD motor symptoms; a finding that is commensurate with the outcomes of separate studies examining the potential benefits of lower STN‐DBS amplitude . Furthermore, reducing STN‐DBS amplitude to approximately 30% of the chronic stimulation value were shown to contribute to poorer performances during post‐urography assessments in a small group of three participants .…”

“…Within the five studies, there were seven experimental conditions investigated; five of which included lowering amplitude and two of which involved increasing amplitude. In studies reporting the effects of lowering amplitude relative to the chronic stimulation value, amplitudes were typically reduced (1) by 50% for one hemisphere; (2) to approximately 80%, 70%, or 30% of the chronic stimulation values; or (3) to a level that was 0.3 V lower than chronic stimulation . In contrast, studies examining the effects of increasing amplitudes included experimental conditions that involved increasing amplitudes (1) to the highest level tolerable for each patient, or (2) to a level that was 0.3 V higher than chronic stimulation …”

“…Specifically, these studies evaluated the effect of shortening pulse widths to 20, 30, 40, and 50 μs or lengthening pulse widths to 90 or 120 μs . Of the two studies that investigated changes in pulse width, one employed a constant‐current amplitude, while the other examined a constant‐voltage system . Although our systematic search strategy identified a number of studies investigating the effect of different electrode polarities on the severity of motor symptoms in post‐operative STN‐DBS PD patients, all were excluded for not meeting one or more of the pre‐defined inclusion criteria.…”

“…In addition to evaluating the effect of alternate stimulation frequencies on the management of motor symptoms in post‐operative STN‐DBS PD patients, this review also considered the effect of experimentally altering amplitude on motor symptoms. The findings of the reviewed studies demonstrated that increasing STN‐DBS amplitude to a level above chronic stimulation (e.g., > 3 V) led to muscle activation patterns that reflected a worse disease state . Interestingly, however, one study reported that patients completed the Stand‐Walk‐Sit test in less time and with fewer number of steps and freezing episodes when STN‐DBS amplitude was increased above the chronic stimulation level, suggesting that higher amplitudes may be beneficial for managing gait‐related difficulties .…”

“…Of these 17 studies, seven investigated very low stimulation frequencies (below 60 Hz), [13][14][15][16][17][18][19] 12 investigated low-frequencies (60-80 Hz), 5,6,16,17,[20][21][22][23][24][25][26][27] and one investigated very high-frequency stimulation (i.e., greater than the usual clinical recommendation of 130 Hz). 22 Given these data, it is evident the majority of research has contrasted high-frequency stimulation with low-frequency stimulation. Nine of the 17 studies examining the effects of alternate stimulation frequencies did so while the other STN-DBS parameters remained unchanged from their chronic stimulation values (i.e., the TEED varied between experimental conditions).…”