What does “cough deficiency” mean in ALS?

ALS can lead to impairment of the respiratory muscles. This can also be associated with a weak cough. The weakness of the cough is referred to as “cough deficiency”. Effective expectoration is particularly important in the case of bronchial infections (bronchitis), as upper respiratory tract infections are associated with a high production of bronchial secretions. The secretions should be removed as quickly and completely as possible by effective coughing in order to reduce obstruction of the airways (respiratory effort) and to prevent colonization of the secretions by bacteria (risk of bacterial bronchitis or the development of pneumonia).

A further necessity for coughing arises after swallowing secretions or food residues. Swallowing (aspiration) can occur more frequently in ALS if there are bulbar symptoms (involvement of the tongue, pharyngeal and laryngeal muscles). If secretions and food particles are swallowed, a cough is necessary to “clear” the airways. Coughing also plays an important role outside of bronchial infections and swallowing in order to transport bronchial secretions and keep the airways clear.

Coughing deficiency is manifested by a reduction in the “coughing thrust”: during the neurological examination, patients are asked to cough vigorously. During this exercise, it is already recognizable and audible if there is a reduction in coughing performance. It is much more accurate to determine the effectiveness of coughing by measuring the airflow when coughing up ( peak cough flow, PCF). Another indication of a possible cough deficiency is provided by the reports of the patients themselves: Some patients notice of their own accord that it is more difficult to cough up effectively.

Cough deficiency can therefore be determined using three pieces of information: The subjective experience of the patient, the physical examination of the cough and the measurement of the PCF value.