INTRODUCTION:Facioscapulohumeral muscular dystrophy (FSHD) rarely progresses to respiratory insufficiency. We describe a patient, in her third trimester of pregnancy, who presented with dyspnea. She progressed to hypercapneic respiratory failure and was eventually diagnosed with FSHD. In order to treat the hypercapneic respiratory failure, non-invasive positive pressure ventilation (NPPV) was started. This therapeutic modality is an effective option in the management of hypercapneic respiratory failure in the setting of FSHD.
CASE PRESENTATION:20 year old G1P0 presented at 32-6/7 weeks gestation complaining of worsening shortness of breath with hypercapneic respiratory failure. Significant medical history included premature birth with respiratory difficulties requiring prolonged hospitalization and multiple urgent care visits for episodes of dyspnea attributed to asthma. Management with bronchodilators, inhaled steroids, and leukotriene inhibitors was ineffective. Symptoms of exercise intolerance, difficulty with mastication, dysphagia, lower extremity weakness, orthopnea and poor quality sleep with daytime fatigue had progressed since childhood. During her pregnancy, sleep fragmentation and nocturnal headaches developed. At regular prenatal visits no hypoxia was noted. At the time of admission, she complained of more dyspnea and sleeping upright for one week. On physical exam she had a soft voice. She was tachypneic with accessory muscle use. Chest wall had diminished excursion with diminished breath sounds at the bases without wheezing. Clubbing, cyanosis, lordosis and kyphoscoliosis were absent. Laboratory data revealed room air arterial blood gasses (ABG) of pH 7.30, PCO2 63, PO2 63, HCO3 31. Transthoracic echocardiogram was unremarkable. Radiologic studies showed no evidence of pulmonary embolism or parenchymal lung disease. Electromyography revealed normal nerve conduction studies without abnormal insertional activity but diffuse myopathic motor unit changes consistent with a chronic myopathy. Bilevel NPPV at 17/7 with 2 liters of oxygen was started with progressive improvement in her clinical picture. Steroids were initiated for fetal maturation. At 35 weeks of gestation labor was induced followed by an uncomplicated forceps-assisted delivery. Upon hospital discharge and at follow up she continued on nocturnal bilevel NPPV with improvement in both respiratory symptoms and ventilation (PCO2 47). Genetic testing confirmed the diagnosis of FSHD.
DISCUSSIONS:FSHD is an autosomal dominant inherited muscular dystrophy with a variable age of onset and rate of progression. Respiratory insufficiency is rare with an incidence of 1% in the Dutch FSHD population. Patients at risk for respiratory failure are severely affected, wheelchair bound with moderate to severe kyphoscoliosis and lumbar hyperlordosis.1 Our patient had none of these risk factors and developed acute hypercapneic respiratory failure in her third trimester of pregnancy. FSHD patients with respiratory failure typically require nocturnal mechanical ventilation. In our case, bilevel NPPV was utilized. To our knowledge, there is only one other case report describing the use of home non-invasive ventilatory support.2.
CONCLUSION:Respiratory failure in FSHD is a rare occurrence that can be effectively managed with non-invasive ventilation rather tracheotomy and mechanical ventilation. Our patient with none of the usual risk factors for acute respiratory failure developed hypoventilation late in pregnancy suggesting that this might be another potential risk factor.
DISCLOSURE:Todd Gienapp, No Financial Disclosure Information; No Product/Research Disclosure Information