From the Research
Phrenic nerve injury is a rare complication of Granulomatosis with Polyangiitis (GPA), with an estimated frequency of less than 1% of GPA cases. The exact incidence is difficult to determine due to limited reported cases in medical literature 1. Phrenic nerve involvement in GPA typically occurs when granulomatous inflammation extends to involve the nerve directly, or when vasculitis affects the vasa nervorum supplying the phrenic nerve. This can lead to diaphragmatic paralysis, resulting in respiratory compromise. Patients with phrenic nerve injury due to GPA may present with dyspnea, especially when lying flat, reduced lung volumes, and elevated hemidiaphragm on imaging.
Clinical Presentation and Diagnosis
The clinical presentation of phrenic nerve injury in GPA can be variable, but common symptoms include exertional dyspnea, orthopnea, and sleep-disordered breathing 1. Diagnostic evaluation requires radiographic and pulmonary function testing, as well as electrodiagnostic assessment to quantitate the nerve deficit and determine the extent of denervation atrophy.
Treatment and Management
Treatment follows standard GPA protocols with immunosuppressive therapy, typically including cyclophosphamide or rituximab for induction, combined with corticosteroids (usually starting with prednisone 1 mg/kg/day, maximum 60-80 mg daily, with gradual tapering) 2, 3, 4. Early recognition and aggressive treatment of GPA is essential to prevent such neurological complications, as established nerve damage may be irreversible even with appropriate immunosuppression. Surgical repair of the nerve injury, such as phrenic nerve reconstruction, may be considered in selected patients with symptomatic diaphragm paralysis 1.
Key Considerations
It is crucial to note that while rituximab has been shown to be effective in treating refractory pulmonary granulomatous inflammation in GPA, patients may still experience chronic otolaryngological manifestations of the disease 3. Therefore, a multidisciplinary approach, combining diagnostic evaluation, surgical treatment, and rehabilitation, is required to achieve optimal long-term outcomes for patients with phrenic nerve injury due to GPA 1.