Modeling of Lung Function Recovery in Neuralgic Amyotrophy With Diaphragm Impairment

Abstract

Background: Neuralgic amyotrophy is an inflammatory peripheral nerve disorder in which phrenic nerve involvement can lead to diaphragm paralysis. The prevalence, magnitude, and time course of diaphragm recovery are uncertain.

Methods: This study modeled the course of recovery of lung function in 16 subjects with diaphragm impairment from neuralgic amyotrophy. The first and last available vital capacity, sitting-to-supine decline in vital capacity, and maximal inspiratory pressures were compared.

Results: An asymptotic regression model analysis in 11 subjects with at least partial recovery provided estimates of the vital capacity at onset (47%, 95% CI 25-68%), the final vital capacity (81%, 95% CI 62-101%), and the half-time to recovery (22 months, 95% CI 15-43 months). In those subjects, there was a significant improvement between the first and last measured FVC (median 44-66%, P = .004) and maximal inspiratory pressure (mean 34-51%, P = .004). Five subjects (31%) with complete recovery had a final sitting-to-supine drop of vital capacity of 16% and a maximal predicted inspiratory pressure of 63%.

Conclusions: Sixty-nine percent of subjects with diaphragm impairment from neuralgic amyotrophy experience recovery of lung function and diaphragm strength, but recovery is slow and may be incomplete.

Keywords: brachial plexus neuritis; diaphragmatic paralysis; longitudinal study; phrenic nerve; respiratory function tests.