Neurol Sci (2013) 34:1243–1245 DOI 10.1007/s10072-012-1195-6
LETTER TO THE EDITOR
Pneumothorax after needle electromyography of the diaphragm: a case report Simon Podnar
Received: 17 May 2012 / Accepted: 5 September 2012 / Published online: 18 September 2012 Ó Springer-Verlag 2012
Dear Editor, 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/m2) 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
S. Podnar (&) Division of Neurology, Institute of Clinical Neurophysiology, University Medical Center Ljubljana, 1525 Ljubljana, Slovenia e-mail:
[email protected]
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
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3. Fig. 1 Surface markings of the medial and inferior borders of the lungs, pleura, chest and sixth to nineth intercostal spaces are drawn on the chest of a healthy subject during forced inspiration. Right midclavicular and anterior axillary lines are also shown. Koepke technique denotes insertion of the needle electrode into the medial recess of the lower intercostal spaces, lateral to midclavicular line [1]. Note that medial recess of the sixth intercostal space is much nearer to lung than medial recesses of the seventh, eighth and nineth intercostal spaces, which makes the latter three much safer sites for needle insertion during electromyographic examination of the diaphragm
neuropathies in addition to a right long thoracic (and slight sensory axillary) neuropathy in our patient. Mostly unilateral phrenic neuropathies have been reported in 6.6 % of patients with idiopathic neuralgic amyotrophy [3]. By contrast, bilateral phrenic neuropathies are much more rare, although previously described in this condition [4]. As part of this patient’s diagnostic evaluation concentric needle EMG of the diaphragm was performed and the patient’s right lung was accidentally punctured, resulting in a large pneumothorax. Fortunately, the complication was effectively resolved by prompt pleural drain insertion. Needle EMG of the diaphragm is considered to rarely result in pneumothorax. Bolton [1] reported this complication only in two mechanically ventilated patients with severe COPD of 1,000 examinations performed. The same group also argued that the needle electrode can be safely inserted into the intercostal spaces between the anterior axillary and midclavicular lines [1]. What are the possible reasons for pneumothorax after needle EMG of the diaphragm?
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Inappropriate position of the needle electrode insertion into the intercostal space. Using the Koepke technique, the needle electrode needs to be inserted into the medial recess of the intercostal space (Fig. 1) [1]. At more postero-superior positions in the intercostal space the underlying lung may be easily penetrated by the needle electrode. Insertion of the needle electrode medial to midclavicular line. The lung follows the reflection of the parietal pleura quite closely until the midclavicular line (i.e., usually the medial recess of the sixth intercostal space). Lateral to that, the distance between them (and between the lower margin of the rib cage and the lung) increases sharply (Fig. 1). The needle electrode can be safely inserted into the intercostal spaces (i.e., 7th–9th) lateral to midclavicular line [1, 5]. Failure to comply strictly with this recommendation was probably the main reason for the pneumothorax reported in this patient. Cranial inclinations of the needle electrode. After insertion it is important to always direct the needle electrode caudally, away from the lung. Complete denervation of the diaphragm. Inability to identify the characteristic bursting pattern of lowamplitude diaphragm MUPs during inspiration may lead to potentially dangerous needle exploration.
Bolton et al. recommended observation of all subjects for 1 h following diaphragm needle EMG. However, experience with our patient suggests that a 1-h observation period may not be long enough, as he did not experience symptoms severe enough to contact us during that period. Routine chest X-ray 1 h after needle EMG of the diaphragm may not resolve the issue either, as a pneumothorax may be too small to be reliably detected initially. Written information with explanation of the procedure, its potential risks, and actions in case of breathing deterioration issued to each patient is mandatory. Particular caution is needed in patients who need bilateral diaphragm EMG. In a patient with unsuccessful insertion of the subclavian catheter, it is regarded unwise to try to insert it contralaterally unless pneumothorax is excluded first. To prevent similar complications, we now use ultrasound guidance routinely in all patients undergoing needle EMG of the diaphragm [6]. However, caution is important also in performing needle EMG examination of other chest wall (e.g., the serratus anterior, the romboidius major, etc.), where the lung is possibly even at higher risk of being punctured. Based on presented experience, the following could be highlighted: 1.
Written informed consent must be obtained by the patients before performing needle EMG of all muscles
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potentially causing pneumothorax (i.e., diaphragm, serratus anterior and rhomboideus). EMG of the diaphragm should be performed only in patients in whom the investigation is expected to affect treatment and/or clarify prognosis. The investigation should be performed only by neurophysiologists experienced in technique in secondary or tertiary centre able to assess rapidly the presence of pneumothorax and consequently begin appropriate therapy.
Acknowledgements The author thanks Dr. Marija MezˇnaricˇPetrusˇa for help with reviewing cadaver specimens, Prof. Janez Zidar for review of the manuscript, and Dr. Dianne Jones for language review. The study was supported by the Republic of Slovenia Research Agency, Grant No. P3-0338.
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References 1. Bolton CF, Chen R, Wijdicks EFM, Zifko UA (2004) Neurology of breathing. Elsevier, Philadelphia 2. Resman-Gaspersˇicˇ A, Podnar S (2008) Phrenic nerve conduction studies: technical aspects and normative data. Muscle Nerve 37:36–41 3. van Alfen N, van Engelen BG (2006) The clinical spectrum of neuralgic amyotrophy in 246 cases. Brain 129:438–450 4. Tsao BE, Ostrovskiy DA, Wilbourn AJ, Shields RW Jr (2006) Phrenic neuropathy due to neuralgic amyotrophy. Neurology 66:1582–1584 5. Chiodo A, Goodmurphy C, Haig A (2006) Diaphragm needle placement techniques evaluated in cadaveric specimens. Arch Phys Med Rehabil 87:1150–1152 6. Boon AJ, Alsharif KI, Harper CM, Smith J (2008) Ultrasoundguided needle EMG of the diaphragm: technique description and case report. Muscle Nerve 38:1623–1626
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