Phrenic nerve conduction studies can be carried out with placement of an esophageal electrode to record diaphragmatic contractions and stimulation of the nerve in the neck either with surface stimulation or with a monopolar needle electrode at the level of the cricoid cartilage 7.Īlternatively, diaphragmatic electromyography may be carried out. MRI is particularly suited to evaluation of Pancoast tumors, and better able to determine tumor extension in such cases. CTĬT has little role in the diagnosis of an elevated hemidiaphragm, as supine position and variable inspiratory effort can significantly alter diaphragmatic height ref. Despite this, it excels at identifying many of the causes of phrenic nerve palsy and is able to acquire volumetric data from base of skull to upper abdomen. In cases of phrenic nerve paralysis, the affected side demonstrates paradoxical upward movement 10. In normal subjects, both hemidiaphragms descend with inspiration. Fluoroscopyįluoroscopic examination of the diaphragm (' sniff test') is useful in assessing diaphragmatic function and involves rapid inspiratory effort and observation of the hemidiaphragms.

If the left hemidiaphragm is higher than the right or the right is higher than the left by more than ~2 centimeters, one of the many causes of diaphragmatic elevation should be sought. This, of course, includes phrenic nerve palsy 10. In some cases the diagnosis is obvious. However, as diaphragmatic position is not symmetric, an understanding of the normal level of the diaphragms is important (see normal position of diaphragms on chest radiography). chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) 3.incidence reduced with ultrasound guidance and use of lower volumes of local anesthetic 12.intrascalene brachial plexus nerve blocks.postoperative: especially cardiac: up to 10% of cases 7,9,11.Many cases are idiopathic or thought to be postviral 8,9.

In cases of bilateral phrenic nerve paralysis, symptoms are not surprisingly more pronounced but are particularly exacerbated when recumbent 1. Respiratory function tests tend to have a restrictive pattern 1. When presentation is directly attributable to phrenic nerve palsy, then patients typically report dyspnea and orthopnea. In many cases of unilateral (majority of cases) phrenic nerve paralysis, patients are asymptomatic 7.

Clinical presentationĬlearly presentation will depend on the underlying cause. The epidemiology will therefore match that of the underlying etiology.

No single demographic is affected, as there are numerous causes of a phrenic nerve palsy.

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