Respiratory Function Changes as Early Signs of Amyotrophic Lateral Sclerosis

Abstract

<b><i>Background:</i></b> The current diagnostic criteria for amyotrophic lateral sclerosis (ALS) may remain unsatisfactory for months or years in the early disease. Pulmonary assessment has never been considered useful in the early diagnosis of ALS, and studies of pulmonary function in this patient category are lacking. <b><i>Objectives:</i></b> The objective of this study was to assess the pulmonary function in subjects with unspecific symptoms of ALS in whom an ALS diagnosis cannot be reached based on the current available guidelines. <b><i>Methods:</i></b> We performed pulmonary function tests, arterial gas analysis, maximal inspiratory (MIP) and expiratory (MEP) pressure, and respiratory drive (P<sub>0.1</sub>) assessment in 35 patients with unspecific neurological symptoms at the time of the visit and those were subsequently diagnosed with ALS 2 years after the initial visit (“pre-ALS”); we compared these patients with 29 patients with established ALS and with 28 control subjects. <b><i>Results:</i></b> Spirometric parameters were not different between the three groups. However, MIP was significantly lower and P<sub>0.1</sub> was significantly increased (with the ratio P<sub>0.1</sub>/MIP significantly higher) in both established and pre-ALS patients compared to controls, while both MIP and P<sub>0.1</sub> were similar between established ALS and pre-ALS. <b><i>Conclusions:</i></b> Changes in MIP, P<sub>0.1</sub>, and P<sub>0.1</sub>/MIP ratio are highly suggestive of preclinical ALS when the spirometry and neurodiagnostic tests are still inconclusive. MIP and P<sub>0.1</sub> are noninvasive measurements that can be easily assessed in an ambulatory setting. Future studies on larger cohorts are needed to validate the use of these parameters in the preclinical diagnosis of ALS as well as in other neuromuscular diseases.

Diagnosis of amyotrophic lateral sclerosis by respiratory function test

“…The main finding of the Polverino et al ’s. paper [ 19 ] is that the respiratory drive (P0.1), the MIP, and their ratio (MIP/ P0.1) are sensitive enough to discriminate patients with pre-clinical ALS from the controls way ahead of time. It should be assessed whether this behavior is specific to ALS or whether it is also shared by other neuromuscular diseases.…”

“…This work by Polverino et al . [ 19 ], therefore, represents a real perspective for an earlier diagnosis of ALS.…”

“…In any case it is noteworthy that patients of this study were selected to include mildly affected ALS patients, who showed slow progression, and that at the time of entry into the study the patients were already classified as defined ALS. In a very recent research the possibility of carrying out an early diagnosis with new indices of respiratory function was evaluated [ 19 ].…”