# Electrical Stimulation May Improve the Feeding and Nutritional Status of Children with Dysphagia
## 8 Technical Parameters of NMES  
NMES uses electrical impulses to elicit muscle contractions. Its effectiveness depends on key biophysical parameters such as waveform type, pulse duration, frequency, current intensity, and electrode placement. These factors influence the depth, comfort, and efficiency of stimulation. Tissue resistance also plays a significant role and is influenced by factors such as skin type, hydration level, and temperature. The key technical aspects of NMES based on the information include impulse parameters, current settings, electrode placement, and factors affecting tissue resistance [98]. Commonly \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Authors/Year** & **Study Type** & **Participants** & **Population** & **Treatment Outcomes** & **Adverse Events** \\ \hline [PERSON] et al., 2019 [87] & Case series & 186 & Children with severe dysphagia & Improvement in feeding and reduced aspiration & Not reported \\ \hline [PERSON] et al., 2024 [88] & Observational & 20 & Children with primary dysphagia & Improved swallowing; reduced enteral feeding & No serious events \\ \hline [PERSON] et al., 2011 [90] & Retrospective & 186 & Children with primary and acquired dysphagia & No improvement in primary, improvement in acquired dysphagia & Not reported \\ \hline [PERSON] and [PERSON], 2019 [90] & Interventional & 5 & Children with cerebral palsy & Reduced aspiration after 4 weeks & Not reported \\ \hline [PERSON] et al., 2015 [91] & RCT & 20 & Children with cerebral palsy & Better swallowing outcomes than control group & Not reported \\ \hline \hline \end{tabular}
\end{table} 
Table 2: \(Cont.\) \begin{table}
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**Advantages** & **Disadvantages** \\ \hline Increased muscle strength and activity & Lack of conclusive clinical evidence \\ Applicability in patients with & Risk of incorrect application \\ severe dysphagia & Neuroplasticity & Cost and limited accessibility \\ Integration with other methods & Discomfort or lack of patient cooperation \\ \hline \hline \end{tabular}
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Table 3: Advantages and disadvantages of NMES in dysphagia therapy in children. used wave forms are symmetrical biphasic rectangular pulses and asymmetrical biphasic pulses. The first one is preferred for large muscle groups, as they ensure balanced current flow and reduce the risk of net charge buildup in tissues. The second one is used for smaller muscles or more targeted stimulation. Typical impulse parameters include the following: pulse duration: 200-400 \(\upmu\)s; frequency: 20-50 Hz to induce tetanic contraction; and duty cycle (stimulation/rest time): e.g., 10 sec on and 30 sec off to minimize muscle fatigue [98; 99; 100]. Current intensity is individually adjusted, typically up to 100 mA (up to 120 mA in some devices), depending on patient's tolerance and application site. Peak output voltage may reach 100-150 V per impulse, depending on skin impedance [100]. In NMES, electrodes should be placed to cover the innervation zone of the target muscle: active electrode--over the motor point (where the nerve enters the muscle); dispersive electrode--along the muscle or nerve pathway. The distance between electrodes affects stimulation depth and spread: the greater the distance, the deeper the stimulation but with reduced selectivity [100]. Tissue resistance (impedance) affects stimulation efficiency. It depends on the application site (dry or keratinized skin has higher resistance), skin hydration, amount of subcutaneous fat, body temperature, and environmental humidity [99]. With longer application time and higher humidity, resistance tends to decrease [101; 102]. Key NMES parameters and their clinical significance are presented in Table 4.  
There are many producers of NMES devices. However, they all work on the same principles and with similar parameters. Table 5 shows three examples of NMES devices: VitalStim Plus (Chattanooga, Dallas, TX, USA), Ecostim (Novartag GmbH, Berlin, Germany), and Vitalstim (Enovis, Surrey, UK).