Pneumothorax after needle electromyography of the diaphragm: a case report

Abstract

Pneumothorax is a well-known and feared complication of needle electromyography (EMG) of the diaphragm. However, pitfalls that may lead to, precautions to avoid and approach after occurrence of pneumothorax have been only briefly described in the literature [1]. Therefore, I report my first patient with idiopathic bilateral phrenic neuropathy and pneumothorax caused by needle EMG of the diaphragm. A 72-year-old retired man (body mass index 30 kg/m) treated for hypertension, but with no other disease (e.g., chronic obstructive pulmonary disease (COPD) or diabetes), underwent lumbar spinal stenosis surgery. On the fifth postoperative day, he suddenly noted severe pain at the tip of the right shoulder, difficulty in moving the arm, and sensory loss in the lateral aspect of the superior third of the arm. He noted that he was not able to breathe while recumbent. X-ray and CT scan of his chest demonstrated bilateral elevation of the diaphragm with basal atelectases. Ultrasound examination also found poor respiratory movement of the diaphragm. Pulmonary function tests showed restrictive defect with hypercapnic respiratory failure. On neurological examination in the fifth week of disease inability to lay supine, paradoxical respiratory abdominal movements, pronounced right-sided winging of the scapula, and slightly diminished sensation over the lateral aspect of the superior third of the right arm were found. On nerve conduction studies [2], no reproducible phrenic nerve compound motor action potentials were found bilaterally. Needle electrode was inserted bilaterally in the medial recess of the sixth intercostal space for EMG of the diaphragm (Fig. 1), and towards the eighth rib in the right middle axillary line for EMG of the serratus anterior muscle; spontaneous denervation activity was found in all three muscles. Furthermore, no characteristic motor unit potential (MUP) firing pattern during inspiration was found in the diaphragm, and severe interference pattern reduction in the right serratus anterior muscle. Nerve conduction studies and EMG of the additional nine, mainly C3–6 segment muscles, were normal. On a follow-up visit 3 months later, the patient reported that he had suffered a right-sided pneumothorax following the electrodiagnostic examination. He denied any subjective difference in perception of the diaphragm needle EMG on the left and right side. In the first hour after electrodiagnostic studies, while waiting outside of our department for transport home, he noted only a slight increase in breathing difficulty. However, his breathing became increasingly difficult during his 2-h journey home. On arrival home he felt like he had ‘‘a stone in his right chest’’. He immediately contacted the local electrodiagnostic physician, who directed him to the local hospital. Chest X-ray demonstrated a large right-sided pneumothorax. A pleural drain was inserted, and breathing returned to the pre-complication state in 1 h. Patient received methylprednisolone 500 mg i.v. on five consecutive days. For treatment of his respiratory failure over-night non-invasive ventilation was started and still continues several years later. Sudden severe shoulder pain, followed by hypesthesia over the lateral aspect of the arm, with scapular winging, probably triggered by the surgical procedure in an anatomically distant region 5 days previously, are all typical of neuralgic amyotrophy [3]. However, according to clinical, electrodiagnostic and imaging studies, the presumed autoimmune process also caused bilateral phrenic S. Podnar (&) Division of Neurology, Institute of Clinical Neurophysiology, University Medical Center Ljubljana, 1525 Ljubljana, Slovenia e-mail: simon.podnar@kclj.si