Abdominal muscle strength in patients with tetraplegia

Am J Respir Crit Care Med. 2000 Mar;161(3 Pt 1):707-12. doi: 10.1164/ajrccm.161.3.9906020.


The abdominal muscles are completely paralyzed after traumatic transection of the cervical cord. To assess the residual pressure-generating capacity of these muscles, we first measured the changes in gastric pressure (DeltaPga) during paired bilateral stimulation of the lower thoracic nerve roots in eight chronic patients with C5-C7 tetraplegia and eight matched unaffected subjects in the seated posture. Stimulations were applied with a 90-mm circular magnetic coil positioned at the level of T10 and connected to a Magstim 250 stimulator. During relaxation at FRC, DeltaPga during maximal stimulation averaged (mean +/- SE) 76.0 +/- 11.7 cm H(2)O in the control subjects, whereas in the patients it was only 29.9 +/- 3.7 cm H(2)O (p = 0.002). Stimulations were next applied during the course of a forced expiration. All patients consistently demonstrated an abrupt increase in esophageal pressure (22.7 +/- 4.5 cm H(2)O), and six of them also showed an increase in expiratory flow. The cumulative thickness of the four abdominal muscles, as measured with an ultrasound probe, was 34% smaller in the patients than in the control subjects and correlated positively with maximal DeltaPga. We conclude that in patients with tetraplegia, muscle atrophy causes a marked reduction in abdominal muscle strength. However, magnetic stimulation of the abdominal muscles elicits increases in intrathoracic pressure that are greater than those required to initiate dynamic airway compression; it might, therefore, improve the clearing of airway secretions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abdominal Muscles / innervation
  • Abdominal Muscles / physiopathology*
  • Adult
  • Electromagnetic Fields
  • Humans
  • Isometric Contraction / physiology*
  • Lung Volume Measurements
  • Male
  • Middle Aged
  • Mucociliary Clearance / physiology
  • Muscular Atrophy / physiopathology
  • Pulmonary Ventilation / physiology
  • Quadriplegia / physiopathology*
  • Respiratory Paralysis / physiopathology*
  • Spinal Cord Injuries / physiopathology
  • Spinal Nerve Roots / physiopathology