Departments: Letters to the Editor
To the Editor
I read with anticipation the research report by Seifart et al1 hoping for a clear presentation on lower extremity neuromuscular electrical stimulation (NMES) or its subset functional electrical stimulation (FES). Unfortunately, as they stated, the authors’ library was limited. I wish that they had corresponded with the authors regarding the articles that were locally unavailable.
The screening method to reduce their original search to only 5 reports for review is unclear to me. I searched my personal database using my understanding of the authors screening criteria and came up with 13 reports; the 5 that they selected plus 2 more that they mentioned (Refs. 23 and 37) and an additional 6. One of the 6, a prospective pretest-posttest control group study with 17 children (9 surgical and 8 FES) by Johnston et al,2 is particularly interesting and showed how electrical stimulation can be as effective as surgery, if not more so.
It was a pleasure to read about the current acceptance of the idea that spastic muscles need to be strengthened for the improvement of function. This proposal was a shock to many in 1993 when I suggested that, for those with cerebral palsy, NMES be applied to the calf muscles for strengthening, function, and correcting an equinus gait.3 The authors, on page 28 of their article, without stating specifics, mentioned that I found something detrimental with task-specific NMES. For the record, it was clinically apparent that electrical stimulation should not be applied to the anterior tibialis muscle in children younger than 5 years because the calf muscles should double in size from age 2 to 5 years. These muscles need time to develop and should not be inhibited or weakened by any means. They are also supposed to double in size again by adolescence, and so they need many years of exercise.
The authors stated on page 26 that I did not describe the subjects or the intervention in sufficient detail. Actually, the journal kindly allowed me more than 5 pages of detail on these topics. I suppose one could always provide more. As published, the report won the APTA annual award for the best article in Physical Therapy on clinical practice.
Table 2 echoes the notion of insufficient detail by assigning my report the category “not specified” (NS) many times. I disagree and contend that most of the Carmick NS entries are errors of fact, interpretation, or table construction (the first 3 dose entries were specified but variable for my cases because I was treating clinical patients whose appointments did not fit neatly into Table 2). For entry 4, frequency, I specified a range of 30–35 Hz. Entry 5, intensity, is arguably listed in error as NS for both Comeaux et al4 and Carmick: “To child’s tolerance” would be more accurate. Although conducting a predesigned study, Comeaux et al4 wisely chose not to treat their 14 subjects as subjects in a laboratory experiment. Entry 6, timing, is partly correct and partly incorrect for both studies. Comeaux et al followed my protocol with variable timing by remote switch during gait treatment, and I used a 15:15 on-off ratio during nongait treatment. Entry 8, ramp, listed as NS for Carmick, was specified as 0.5–2.0 seconds for static activities and 0.0 seconds for gait. Entry 7, pulse width (pulse duration is the correct term as it denotes time), is listed erroneously in the study of both Comeaux et al and Carmick. Both studies as stated by Comeaux et al used the same Medtronic instrument, which had a fixed pulse duration of 300 μs, as specified in my report. However, the authors listed pulse duration as 100 μs for Comeaux et al and NS for Carmick. One expects that these details would have been reported if the authors had more carefully read these 2 articles.
The author’s first paragraph under the Stimulation Parameters section on page 28 seems confused regarding NMES and FES due to trying to distinguish between the two. This confusion starts with the third paragraph of the Introduction section on page 23 where we find erroneous statements on intensity and timing referenced to a private communication (authors’ Ref. 14). The reader should consult the APTA’s terminology guide5 for the historical origin of FES as an orthotic substitute and Baker et al6 for history and a current FES/NMES comparison. They state in a concise summary sentence: “Thus, FES is a subset of treatment programs of the more broadly defined term NMES.”
Seifart et al concluded that future studies should clearly distinguish FES from NMES. In fact, this is much ado about nothing. To be functional, both FES and NMES must be task specific. We do need further electrical stimulation studies to determine the best muscle choices, parameters, and timing for stimulation according to the task to be done.
Judy Carmick, PT, MA
Children’s Physical Therapy Clinic
1. Seifart A, Unger M, Burger M. The effect of lower limb functional electrical stimulation on gait of children with cerebral palsy. Pediatr Phys Ther
2. Johnston TE, Finson RL, McCarthy JJ, et al. Use of functional electrical stimulation to augment traditional orthopaedic surgery in children with cerebral palsy. J Pediatr Orthop
3. Carmick J. Clinical use of neuromuscular electrical stimulation for children with cerebral palsy. Part 1: Lower extremity. Phys Ther
4. Comeaux P, Patterson N, Rubin M, et al. Effect of neuromuscular electrical stimulation during gait in children with cerebral palsy. Pediatr Phys Ther
5. American Physical Therapy Association. Electrotherapeutic Terminology in Physical Therapy: Section on Clinical Electrophysiology
. Alexandria, VA: American Physical Therapy Association; 1999.
6. Baker LL, Wederich CL, McNeal DR, et al. Neuromuscular Electrical Stimulation: A Practical Clinical Guide
. 4th ed. Downy, CA: Rancho Los Amigos National Rehabilitation Center; 2000.