The study aims as the principal objective to compare two approaches to diagnosis unilateral diaphragmatic paralysis: transdiaphragmatic pressure (Pdi) measurement versus phrenic nerve conduction (NPC) study.

The secondary objective of the study is the strengths and weaknesses of different tests. Diagnostic threshold values.

Inpatient patients in Raymond Poincaré hospital are informed of the utilization of their data retrospectively by the hospital's welcome booklet and reports of patients' hospitalization.

Period of date collected: November 2015 to June 2018.

The reference standard was the diagnosis established during a multidisciplinary meeting held during patient management involving a neurologist, an electrophysiologist, a pulmonologist, and a respiratory physiologist. The medical history, physical findings, and all available investigations including imaging studies, ENMG, lung function tests, and Pdi measurement were considered during the meeting.

Inclusion Criteria:

• Patient ≥ 18 years;
• Available data of Pdi and PNC;
• Suspected unilateral diaphragmatic paralysis.

Exclusion Criteria:

• Abnormalities in thoracic wall which susceptible to modify the investigation's results;
• Scoliosis;
• Pleural effusion.

Adult patients suspected unilateral diaphragmatic paralysis with available Pdi and PNC data.