Changes of the phrenic nerve motor response in amyotrophic lateral sclerosis: longitudinal study.
OBJECTIVE
Phrenic nerve motor amplitude (Diaphr Ampl) is predictive of hypoventilation in amyotrophic lateral sclerosis (ALS). We aimed to evaluate its change over disease course and to correlate it to other measurements.


METHODS
Forty-nine unselected patients (35 men, 13 bulbar-onset, 56.5+/-8.9 years) with definitive or probable ALS were included. They were evaluated at entry (time 0) and 4-6 months (5.2+/-1.0) later (time 1) with: functional ALS rating scale (ALS-FRS) and respiratory subscore (ALS-FRSr); forced vital capacity (FVC); maximal inspiratory pressure (MIP); mean O(2) saturation overnight (SpO(2)mean); sniff maximal inspiratory pressure (SNIP); Diaphr Ampl and mean amplitude of the ulnar nerve response (ADM Ampl).


RESULTS
ALS-FRS, ALS-FRSr, Diaphr Ampl, FVC, SNIP, ADM Ampl (p<0.01) and SpO(2)mean (p<0.05) declined significantly. MIP did not change significantly (p=0.203). Coefficient of variation was similar for FVC, Diaphr Ampl, ADM Ampl and ALS-FRS but higher for SNIP. The percentage of change for Diaphr Ampl was significantly correlated to FVC and SNIP, but not to ADM Ampl or ALS-FRS.


CONCLUSIONS
Diaphr Ampl decreased significantly in a short period of time and its change is correlated to other respiratory tests. This test can be useful in patients with marked facial weakness or uncooperative.


CONCLUSIONS
Diaphr Ampl is useful to monitor respiratory function in ALS patients and can be applied in clinical trials.
Pinto
Susana
S
Neuromuscular Unit, Institute of Molecular Medicine - Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
Geraldes
Ruth
R
Department of Neurosciences, Hospital de Santa Maria, Lisbon, Portugal.
Vaz
Nuno
N
Neuromuscular Unit, Institute of Molecular Medicine - Faculty of Medicine, University of Lisbon, Lisbon, Portugal.
Pinto
Anabela
A
Neuromuscular Unit, Institute of Molecular Medicine - Faculty of Medicine, University of Lisbon, Lisbon, Portugal; Department of Physical Medicine and Rehabilitation, Hospital de Santa Maria, Lisbon, Portugal.
de Carvalho
Mamede
M
Neuromuscular Unit, Institute of Molecular Medicine - Faculty of Medicine, University of Lisbon, Lisbon, Portugal; Department of Neurosciences, Hospital de Santa Maria, Lisbon, Portugal. Electronic address: mamedemg@mail.telepac.pt.
D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis / Q000503:physiopathology*; D003964:Diaphragm / Q000294:innervation / Q000502:physiology; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D007040:Hypoventilation / Q000175:diagnosis / Q000503:physiopathology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D010791:Phrenic Nerve / Q000502:physiology*; D011446:Prospective Studies; D012129:Respiratory Function Tests / Q000379:methods