Can bilateral bronchospasm be a sign of unilateral phrenic nerve palsy after supraclavicular brachial plexus block?

Two Cases of Respiratory Insufficiency Secondary to Pre-procedural Nerve Blocks for Upper Extremity Injuries

Interscalene nerve blocks are common procedures performed before upper extremity surgeries in order to provide post-op pain relief and improve recovery time. Here we present two cases of patients who underwent a unilateral supraclavicular and bilateral interscalene nerve block, respectively. The first patient had no risk factors but the second presented with a body mass index of 45.5 and a history of symptoms consistent with obstructive sleep apnea but never diagnosed. Both patients experienced some form of respiratory distress diagnosed via changes in chest x-ray and clinical presentation. The mechanism of injury that occurs in these procedures is typically from inadvertent damage to the phrenic nerve. Mild adverse effects in interscalene nerve block are relatively common. However, there is minimal data in regards to performing bilateral interscalene nerve blocks. The purpose of this study is to highlight that severe complication in both high and low-risk patients can occur but may be reduced with a safer approach and more effective communication among multidisciplinary team members.

Phrenic nerve block caused by interscalene brachial plexus block: breathing effects of different sites of injection

Background

Interscalene brachial plexus (ISB) block is often associated with phrenic nerve block and diaphragmatic paresis. The goal of our study was to test if the anterior or the posterior ultrasound guided approach of the ISB is associated with a lower incidence of phrenic nerve blocks and impaired lung function.

Methods

This was a prospective, randomized and single-blinded study of 84 patients scheduled for elective shoulder surgery who fullfilled the inclusion and exclusion critereria. Patients were randomized in two groups to receive either the anterior (n = 42) or the posterior (n = 42) approach for ISB. Clinical data were recorded. In both groups patients received ISB with a total injection volume of 15 ml of ropivacaine 1 %. Spirometry was conducted at baseline (T₀) and 30 min (T₃₀) after accomplishing the block.

Changes in spirometrical variables between T₀ and T₃₀ were investigated by Wilcoxon signed-rank test for each puncture approach. The temporal difference between the posterior and the anterior puncture approach groups were again analyzed by the Wilcoxon-Mann-Whitney test.

Results

The spirometric results showed a significant decrease in vital capacity, forced expiratory volume per second, and maximum nasal inspiratory breathing after the Interscalene brachial plexus block; indicating a phrenic nerve block (p <0.001, Wilcoxon signed-rank). A significant difference in the development of the spirometric parameters between the anterior and the posterior group could not be identified (Wilcoxon-Mann-Whitney test). Despite the changes in spirometry, no cases of dyspnea were reported.

Conclusion

A different site of injection (anterior or posterior) did not show an effect in reducing the cervical block spread of the local anesthetic and the incidence of phrenic nerve blocks during during ultrasound guided Interscalene brachial plexus block. Clinical breathing effects of phrenic nerve blocks are, however, usually well compensated, and subjective dyspnea did not occur in our patients.

Trial registration

German Clinical Trials Register (DRKS number 00009908, registered 26 January 2016).

Failing phrenics: an obscure cause of exertional dyspnea: Case report and literature review

INTRODUCTION

Idiopathic phrenic nerve palsy is a rare cause of exertional dyspnea. We present a case of a patient presenting with worsening dyspnea of an unknown etiology found to be related to bilateral phrenic nerve palsy.

DISCUSSION

Forty-two-year-old man presented to our emergency department with exertional dyspnea, orthopnea, and a left lower lobe consolidation treated initially as bronchitis by his primary physician as an outpatient, then subsequently as pneumonia at another institution, with no improvement in symptomatology. After admission to our hospital, CT chest demonstrated only supradiaphragmatic atelectatic changes. Echocardiography was normal. Bronchoscopy was contemplated however the patient could not lie flat. A fluoroscopic sniff test demonstrated diaphragmatic dysfunction and pulmonary function tests revealed restrictive pulmonary disease with evidence of neuromuscular etiology. Nerve conduction studies confirmed bilateral phrenic neuropathy. He was referred to a specialized neuromuscular disease center where subsequent workup did not demonstrate any specific etiology. A sleep study confirmed sleep disordered breathing suggestive of diaphragmatic paralysis and he was discharged on bi-level positive pressure ventilation.

CONCLUSION

This is a unique case of exertional dyspnea and orthopnea from diaphragmatic paresis caused by bilateral phrenic nerve palsy where the initial workup for pulmonary and cardiovascular etiologies was essentially unremarkable. Shortness of breath and orthopnea caused by phrenic neuropathy is a rare condition, yet has a variety of etiologies. Our case suggests a template to the diagnostic approach, management, and follow up of bilateral phrenic nerve palsy.