title: Altered activation of the diaphragm in late-onset Pompe disease.
abstract: Pompe disease is an inherited neuromuscular disorder that affects respiratory function and leads to dependence on external ventilatory support. We studied the activation of the diaphragm using bilateral phrenic magnetic stimulation and hypothesized that diaphragm compound muscle action potential (CMAP) amplitude and evoked transdiaphragmatic pressure (Twitch PDI) would correlate to disease severity. Eight patients with late onset Pompe disease (LOPD, aged 14-48 years) and four healthy control subjects completed the tests. Maximal Twitch PDI responses were progressively reduced in patients with LOPD compared to control subjects (1.4-17.1cm H2O, p<0.001) and correlated to voluntary functional tests (p<0.05). Additionally, CMAP amplitude (mA) was lower in the patients who used nighttime or fulltime ventilatory support, when compared to controls and patients who used no ventilatory support (p<0.005). However, the normalized (%peak) Twitch PDI and CMAP responses were similar between patients and controls. This suggests a loss of functional phrenic motor units in patients, with normal recruitment of remaining motor units.
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, FL, USA; Department of Pediatrics, University of Florida, Gainesville, FL, USA. Electronic address: bksmith@phhp.ufl.edu.
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Smith
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville, FL, USA.
authors.forename: Manuela
authors.initials: M
authors.lastname: Corti
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
authors.forename: A Daniel
authors.initials: AD
authors.lastname: Martin
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
authors.forename: David D
authors.initials: DD
authors.lastname: Fuller
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville, FL, USA.
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Byrne
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D003964:Diaphragm / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006009:Glycogen Storage Disease Type II / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D055909:Magnetic Field Therapy; D008297:Male; D008875:Middle Aged; D010791:Phrenic Nerve / Q000503:physiopathology; D011312:Pressure; D012121:Respiration, Artificial; D014797:Vital Capacity; D055815:Young Adult
keywords: Diaphragm; Neuromuscular; Pompe; Stimulation; Ventilator