INTRODUCTION

Unilateral and bilateral diaphragm paralysis may be caused by motor neuron disease, myopathy, inflammatory myositis, phrenic nerve injury, viral infection, cervical spondylosis, malignancy, or may be idiopathic. Unilateral diaphragm paralysis is more common than bilateral disease and may be discovered incidentally on a chest radiograph. Bilateral diaphragmatic paralysis is usually seen in the context of severe generalized muscle weakness. In some cases, however, the diaphragm is the initial or only muscle involved.

An overview of the different therapies available for the treatment of diaphragmatic paralysis will be presented here. The etiology, assessment, and physiologic effects of unilateral and bilateral diaphragmatic paralysis are discussed separately. (See "Causes and diagnosis of bilateral diaphragmatic paralysis".)

UNILATERAL PARALYSIS

Most patients with unilateral diaphragmatic paralysis are asymptomatic and require no treatment (image 1). The prognosis is good in this setting, and the paralysis is of little clinical relevance in the absence of new or underlying pulmonary disease [1-3].

Some patients with unilateral diaphragmatic paralysis complain of dyspnea. This is most likely to occur with the increased ventilatory demands of intense physical activity or the presence of superimposed pulmonary disease. Treatment of the diaphragmatic paralysis may be considered when the dyspnea is disproportionate to the degree of physical activity or to the severity of the lung disease.

Surgical plication — Surgical plication of the affected hemidiaphragm has provided excellent results in carefully selected patients [4-12]. This operation is performed using an open, thoracoscopic, or laparoscopic approach and involves creating folds in the diaphragm and suturing them in place to reduce mobility of the paralyzed hemidiaphragm (figure 1) [5,13,14]. Plication usually results in improvement in lung function, exercise endurance, and dyspnea [10,14]. The likely mechanism is improved function of the healthy hemidiaphragm and of the accessory muscles of inspiration [15].