Detection of the motor points of the abdominal muscles

Abstract

Purpose: Abdominal Functional Electrical Stimulation (AFES) is a technique intended to improve respiratory functionin tetraplegia where breathing is affected due to abdominal muscle paralysis. Although it is known that optimal muscle contraction is achieved when electrical stimulation is applied close to the muscle motor point, AFES studies have used a variety of electrode positions. This study aims to investigate the feasibility of using Neuromuscular Electrical Stimulation to detect the motor points of the abdominal muscles, and to evaluate the intrasubject repeatability and intersubject uniformity of their positions, to find the most suitable AFES electrode location.Methods: Low frequency stimulation (0.5 Hz) was applied to the abdominal muscles of 10 able bodied and 5 tetraplegic participants. The electrode positions which achieved the strongest muscle contractions were recorded as the motor point positions, with measurements repeated once. For 5 able bodied participants assessments were repeated after 18 months, in seated and supine positions.Results: Intersubject uniformity ranged from 2.8% to 8.8%. Motor point positions were identified with intrasubject repeatability of <1.7 cm, deemed adequate relative to standard AFES electrode size. Intrasubject repeatability shows motor point positions changed little (<1.7 cm) after 18 months but varied between seated and supine positions with repeatability of up to 3.1 cm. Conclusions:A simple technique to locate the motor points of the abdominal muscles is presented and shown to have an adequate intrasubject repeatability, enabling the optimum AFES electrode location to be identified for each user.

Abdominal functional electrical stimulation to improve respiratory function after spinal cord injury: a systematic review and meta-analysis

“…Various solutions exist to facilitate such standardisation. Firstly, McCaughey et al 45 propose the use of electrical stimulation to detect the motor points of the abdominal muscles, enabling standardisation of electrode placement. A number of techniques have also been proposed to standardise the muscle contraction achieved with abdominal FES.…”

Abdominal Functional Electrical Stimulation to Assist Ventilator Weaning in Acute Tetraplegia: A Cohort Study

“…Stimulation was applied during exhalation via surface electrodes (33 mm x 53 mm rectangular, PALS, Axelgaard, USA) placed over the motor points of the rectus abdominis and external oblique muscles on both sides of the body, as shown in Fig 3 . Motor points were detected using a previously described technique [ 22 ].…”

Abdominal functional electrical stimulation to enhance mechanical insufflation-exsufflation

“…Motor points were detected using a previously described technique. 13

Figure 1Schematic diagram of electrode placement showing four electrode pairs positioned to stimulate the motor points of the external oblique (outer electrodes) and rectus abdominis (inner electrodes) muscles on both sides of the body.

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