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Working with vocaSTIM®


Electro diagnostic methods are used to initially detect the degree of damage and to monitor the therapy process for peripheral pareses. In physical therapy, in particular the so called I/T curve has established itself, providing substantial and relatively exact results on the one hand while being very costly and time consuming in its realization. Because it is easy and quick to implement, the determination of the so called “accommodation quotient“ (ACC) has proven to be of value as a means of electro diagnosis in the context of NMEPS and NMEAS. The diagnosis is based on the physiological phenomenon of accommodation ability that shows significant differences between damaged and intact motor nerves: a damaged/ denerved nerve-muscle system suffers losses of accommodation ability or even loses it completely. When stimulated with adequate electrical pulses, it for this reason reacts even at considerably lower amperage then a healthy one. The varying accommodation ability does not only form the basis for the accommodation quotient as a quantitative function check, but also for selecting the electrical pulses appropriate for therapy. vocaSTIM®-Master has a menu to determine the accommodation quotient conveniently, and additionally offers the possibility to operate the device via foot switch in order to have your hands free for the laryngoscopy needed at the same time.


In general, the electrotherapy treatment unit with vocaSTIM® consists of two sequences: 

  • the so called preheating with appropriate current types for promoting blood circulation
  • the actual neuromuscular electro-phonatoric/ electro-articulatory stimulation with appropriate pulses (NMEPS/ NMEAS) 

Pahn has defined exact NMEPS current parameters for the varying degrees of damage determined with the accommodation quotient. They are represented in the vocaSTIM® treatment recommendations (indication register), where they can be accessed directly. The treatment recommendations differ in the pulse form used, pulse duration and release time (defined by the sequence of functional exercises).  The NMEPS follows the stimulation procedure of the so-called intentional exercises according to Förster. This procedure combines the attempt to provoke an intended contraction (in case of NMEPS: phonatoric functional exercises) with the manual release of stimulation current by means of a manual trigger. Intentional exercises are especially indicated with psychogenic paralyses and remaining functional paralyses. They represent important feedback for efficiently readjusting the central nervous regulation. However, this requires a high training frequency (several times a day, short intervals).  

The practical implementation of the electro-stimulation with articulation (NMEAS) depends on the degree of damage, similar to the stimulation of larynx pareses. The degree of damage can be determined measuring the accommodation or, if this is not possible, depending on the exhaustion during the exercise. The exhaustion manifests itself in decreasing clarity of articulation. Contents of the exercise are now speech sounds. In case of coexistent larynx pareses, these patterns are used additionally. Clearing the throat and breathing in are maintained to stimulate damaged sensors. Yawning and laughing are included in the cycle to achieve all movements and tensions of these muscles usable for articulation. For daily exercise at home, this pattern is run with corresponding CDs. To stimulate swallowing, the same current characteristic as for articulation is used. Pressing the manual trigger can be difficult. This applies to two-sided pareses of the arms or one-sided pareses, if the patient wants to hold and direct a spoon, fork or cup himself with the arm he can use. A foot switch is provided in case the leg can be moved.

In general, a monopolar attachment method is used for NMEPS and NMEAS on surface electrodes. To do so, an indifferent electrode with a larger surface is used. A smaller electrode fixed over the area to be stimulated as active stimulation electrode serves as the different electrode.