Diaphragmatic paralysis can be unilateral or bilateral.
Clinical features are highly variable according to underlying aetiological factor:
- unilateral paralysis: asymptomatic in most of the patients as the other lung compensates
- may have dyspnoea, headaches, fatigue, insomnia and overall breathing difficulty
- bilateral diaphragmatic palsy can be a medical emergency; they present with severe dyspnoea, even with mild exertion
- idiopathic: accounts for ~70% of the cases
- phrenic nerve palsy, which in turn can occur from
- Erb's palsy (birth trauma)
- muscular disorders
- iatrogenic causes
- cerebral hypoventilation syndrome (Ondine's curse)
Normally the right dome of the diaphragm is higher in position as compared to the left dome, if the left dome of the diaphragm is elevated (>2 cm) diaphragmatic palsy should be suspected.
Fluoroscopic examination of the diaphragm ("sniff test") very useful in diagnosing a diaphragmatic paralysis. In normal individuals, both hemidiaphragm will descend with inspiration. In cases of unilateral diaphragmatic paralysis, the affected side demonstrates a paradoxical upward movement.
An alternative to fluoroscopy in diagnosing this condition, particularly useful in the paediatric population. Real-time ultrasound is ideal for evaluation of spontaneous respiratory diaphragmatic motion (may require temporary disconnection of the ventilator). This can be performed in the axial plane to compare the two hemidiaphragm simultaneously. Additional coronal or sagittal M-mode can help quantify the degree of movement of each individual hemidiaphragm. Diagnostic criteria include paradoxical movement, excursion of less than 4 mm, and a difference >50% between the excursion of one hemidiaphragm compared to the other.
Treatment and prognosis
Patients with unilateral diaphragmatic paralysis do not require treatment. There may be an option for phrenic nerve stimulation in some cases.
On a chest radiograph consider:
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