Abdominal muscle strength in patients with tetraplegia.
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.
Estenne
M
M
Department of Chest Medicine, Erasme University Hospital, Brussels, Belgium. mestenne@ulb.ac.be
Pinet
C
C
De Troyer
A
A
D000009:Abdominal Muscles / Q000294:innervation / Q000503:physiopathology*; D000328:Adult; D004574:Electromagnetic Fields; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D009079:Mucociliary Clearance / Q000502:physiology; D009133:Muscular Atrophy / Q000503:physiopathology; D012123:Pulmonary Ventilation / Q000502:physiology; D011782:Quadriplegia / Q000503:physiopathology*; D012133:Respiratory Paralysis / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology; D013126:Spinal Nerve Roots / Q000503:physiopathology