One Year of Home-based Functional Electrical Stimulation (FES) in Complete Lower Motor Neuron Paraplegia: Recovery of Tetanic Contractility Drives the Structural Improvements of Denervated Muscle.

Authors: Kern H1, Carraro U2, Adami N2, Biral D3, Hofer C1, Loefler S1, Vogelauer M1, Mayr W4, Rupp R5, Zampieri S6.

Source: Neurol Res. 2010 Feb;32(1):5-12

Keywords: CT scan, tetanic contraction, functional electrical stimulation, human, long-term denervation, lower motor neuron lesion, paraplegia, spinal cord injury, home-based daily FES training

Abstract:

Objective: Spinal cord injury (SCI) causes muscle atrophy, which is particularly severe, due to inability to
perform tetanic contractions, when lower motor neurons (LMN) are involved. We performed a longitudinal
study in 25 Europeans suffering from complete conus cauda syndrome from 0.7 to 8.7 years comparing
functional and structural thigh muscle properties before and after 2 years of home-based daily training by
functional electrical stimulation (FES).The mid-term results after 1 year and preliminary muscle biopsy
observations at project end-point from a subset of subjects are here reported.
Methods: Muscles were electrically stimulated at home by means of large surface electrodes and a customdesigned
stimulator. The poor excitability of the LMN denervated muscles was first improved by twitchcontraction
training. Then, tetanic contractions against progressively increased loading were elicited.
Finally, standing-up exercises were daily performed. The bulk of thigh muscle was estimated by transverse
computer tomography (CT) scan and force measurements. Needle biopsies of vastus lateralis were
harvested before and after 2 years of FES.
Results: The 1 year home-based daily FES training induced: (1) very similar increases in muscle excitability
and contractility in right and left legs; (2) feasibility to elicit tetanic contractions by means of train-stimulation
with about ten times improvement of muscle force; (3) increase in the 26% of muscle bulk, as shown by CT
scan analyses, improving appearance of limbs and muscle cushioning; (4) myofiber size increase (z94%)
in a small series of muscle biopsies obtained after 2 years of FES. None of the subjects that performed
1 year home-based daily FES training (20 persons) had worsened their functional class, while 20% (4/20)
improved to functional class 4, that is, the ability to stand.
Discussion: The European Union (EU) Project Rise shows that ‘home-based daily FES training’ is a safe and
effective therapy that may maintain life-long physical exercise by active muscle contraction (FES is the only
option for denervated muscle) as a procedure to recover the early-lost tetanic contractility of denervated
muscle, and to counteract muscle atrophy in order to prevent clinical complications.

Affiliations:

1 Ludwig Boltzmann Institute of Electrostimulation and Physical Rehabilitation, Department of Physical Medicine,
Wilhelminenspital, A-1171 Vienna, Austria
2 Laboratory of Translational Myology of the Interdepartmental Research Center of Myology, Department of Biomedical
Science, University of Padova, I-35121 Padova, Italy
3 C.N.R. Institute of Neuroscience, Department of Biomedical Science, University of Padova, I-35121 Padova, Italy
4 Center for Biomedical Engineering and Physics, Medical University of Vienna, Vienna
5 University Clinic of Orthopaedics, University Heidelberg, Heidelberg, Germany
6 Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy