Unilateral diaphragm paralysis: Etiology, impact, and natural history

Aim. The etiology, clinical impact, natural history and best therapy of unilateral diaphragm paralysis (UDP) are incompletely understood. This condition is not amenable to pacing, which requires an intact phrenic nerve. Methods. Clinical records of patients with UDP referred to our diaphragm center were reviewed. Results. Thirty-six patients (28 male, 8 female) aged 1 month to 78 years (mean 47.8 years) with UDP evaluated from 1983 to February 2007 were reviewed. Etiology was postsurgical in 13 (36%), tumor (with surgery or radiation therapy) in 7 (19%), idiopathic in 6 (17%), trauma (motor vehicle accident or head injury) in 5 (14%), polio in 3 (8%), and viral in 2 (6%) patients. 28 patients (78%) were symptomatic; 8 (22%) carried a diagnosis of coexisting chronic obstructive pulmonary disease. Mean duration of paralysis was 57.9 months (range up to 261 months). The left diaphragm was involved in 23 cases (64%) and the right in 13 (36%). Mean forced expiratory volume (FEV1) was 1 915 mL (61.3% of predicted) and mean forced vital capacity (FVC) was 2 432 mL (62.9% of predicted). Mean pO₂ was 69.9 mmHg (range 49 to 124), indicating considerable shunting through underventilated lung. Pulmonary infection affected 3 patients (8.4%). Diaphragm function returned in 17% of patients (mainly children) at mean of 10.3 months. Four incapacitated patients (11 %) were treated surgically, with resection of the hemi-diaphragm. Surgical exploration revealed neurogenic atrophy of the diaphragm muscle. All 4 resected patients showed clinical, oxymetric, and spirometric improvement. Conclusion. The conclusion is drawn that: 1) UDP may be traumatic, tumor-related, iatrogenic, or idiopathic; 2) UDP decreases pO₂ substantially and breathing capacity by more than 1/3; 3) spontaneous recovery is possible; 4) UDP is not intrinsically lethal; 5) occasional patients are incapacited; 6) diaphragm resection produces clinical improvement via lower lobe re-expansion; 7) the incapacity incurred by UDP is mild compared to the clinical spectrum of bilateral diaphragm paralysis.