NMES Parameters

After another productive afternoon of reviewing the literature, we now feel we have successfully wrapped our heads around the appropriate NMES parameters for treatment in regards to rehabilitation of the upper limb post stroke. We found these parameters to be remarkably similar to those regarding the other limbs of the body post stroke, thus coming to the conclusion that NMES parameters do not change a great deal from limb to limb. Infact, the following parameters are enough to suffice the recovery of many different body segments post stroke. All the reviewed literature had varying stimulation parameters, thus leaving us to believe NMES stimulation parameters are not specifically crucial in determining the motor outcomes, as all of the studies we read through resulted in some degree of positive outcomes.

Table 3.1: An Example of Parameter Guidelines for NMES Upper Limb Function Post Stroke; (NMES Guidelines for Treatment, 2010)

Electrode Placement	Important to confine the electrode placement to the treatment area thus minimising the overflow to other muscles. Therefore selection of the largest possible electrode within these guidelines is optimal. Negative electrode placed over posterior deltoid. Positive electrode placed above spine of the scapula, over supraspinatus muscle (avoiding placement over the upper trapezius muscle)
Pulse Frequency	25-50Hz
Pulse Duration	200-300 microseconds
Ramp	Optimally 1-3 seconds (however use patient comfort as the guide)
On:Off Cycle	Initially 1:3 ratio implemented. Important muscular fatigue is avoided. Fatigue can be measured by palpating the amount of sublaxation evident at the end of the session of each treatment. GOAL; increase ‘on’ time by 2 seconds daily or every treatment session until achievement of 24-30 seconds. Once this ‘on’ time benchmark is achieved, aim is to decrease ‘off’ time in 2 second intervals. Optimal goal is to achieve a 12:1/ 15:1 ratio.
Waveform	Asmmetrical Biphasic. A symmetrical biphasic waveform has been shown  to reduce the amount of amplitude needed to achieve a stimulated muscle contraction. This reduced current intensity decreases the amount of superficial sensory activation, often making the patient more comfortable and, thus, more willing to comply with the treatment program.
Intensity	A tetanised-muscle contraction- 12.5Hz. Fatigue should be monitored during treatment sessions to ensure reduction is maintained.
Treatment Duration	NMES application in clinical setting à progressing to a home program as quickly as possible. Initially 3x 30 minute daily sessions. The program ideally continues until the individual regains independant functional control of the upper limb musculature.

After looking at the parameters for NMES responsible for optimal functional recovery, we began to wonder how they differ from other electrotherapy modalities. Balanger (2010) explains the varying optimal frequencies are the most significant difference between NMES and other electrical stimulation modalities. TENS for example, uses frequencies between 1-200Hz in comparison to the pulse frequency of 50Hz employed most commonly by NMES. The pulse frequency of 50Hz utilized by NMES is ideal for muscle strengthening due to the resulting fused titanic contraction within the muscle fibres, which in turn increases fibre strength (Balanger, 2010).


According to Chae, et al (2008) NMES is the electrical stimulation device of choice in relation to upper limb stroke as NMES provides therapeutic and functional benefits that lead to enhanced functions, however it doesn’t directly provide function. Chae, et al (2008) explains the importance of the prerequisites the patient must possess in order to achieve the most effective results. These include; mediated motor learning, concurrent volitional effort and high functional content. 

Figure 3.1; NMES stimulation of the wrist used for optimal functional recovery of the wrist

Excited by another discovery, we have included additional NMES Guidelines which include NMES parameters associated with finger flexion, extension, thumb opposition and grip re-education of the lumbrical muscles.

NMES Hand Rehabilitation Guidelines;

http://www.empi.com/uploadedFiles/Empi_Products/Pain_Management_-_TENS/hand.pdf

Figure 3.2; NMES has a significant impact on restoring optimal functional ability of a stroke patients hand

  Figure 3.3; An example of the use of NMES optimally mimicking functional tasks, for example the grasping action in a CVA patient

The next time we cross paths will be looking further into the research and studies which demonstrate supportive evidence towards the NMES treatment of the upper limb recovery post stroke - another area which promises exciting findings!

Until then,

Hayley and Meg

REFERENCES;

Belanger, A.Y. (2010) Therapeutic Electrophysical Agents. Evidence Based Practice. 2^nd Edition. Philadelphia. Lippincott Williams & Wilkins.

Chae, J., Bethoux, F., Bohinc, T., Dobos, L., Davis, T. & Friedl, A. (1998) Neuromuscular Stimulation for Upper Extremity Motor and Functional Recovery in Acute Hemiplegia. Stroke. (29) 975-979.

NMES Guidelines for Treatment. (2010) Retrieved February 25, 2011.

http://www.empi.com/uploadedFiles/Empi_Products/Pain_Management_-_TENS/gait

IMAGES;

http://www.drakecenter.com/page/Neuromuscular-re-education-and-strengthening.aspx

http://www.couragecenter.org/ContentPages/stilwellmed4.aspx

http://www.electrostim.ro/index_e.php?p=MICROSTIM2v2_stimulator

http://www.sciencephoto.com/images/download_lo_res.html?id=777200448

http://www.flickr.com/photos/existentialexits/323164114/