Case Presentation:
A 64‐year‐old man presented with sporadic hiccups, transient apnea, severe left‐sided chest pain, and diaphoresis for 6 months. The above constellation was associated with epigastric/left‐sided pulsatile motions under the left thoracic cage, herein referred to as diaphragmatic myoclonus. His medical history revealed ischemic cardiomyopathy status post percutaneous coronary intervention, obstructive sleep apnea on continuous positive airway pressure, 10 × 13 mm saccular aneurysm at the aortic arch, hypertension, and diabetes mellitus. Episodes occurred about twice a day, while the patient was awake, lasting 10–20 seconds, with abrupt onset and termination. The ordeal was distressing to the patient, particularly the chest pain and apnea. Physical examination during the latter episodes revealed diaphragmatic fluttering (initially missed) on palpation at the left diaphragmatic line. Apart from severe distress, inability to breathe, and assumption of the fetal position, the remainder part of the physical examination was normal. Chest x‐ray showed cardiomegaly, whereas thoracic CT revealed no evidence of pulmonary embolus and confirmed the previously found aneurysm of the aortic arch, unchanged from previous studies. Abdominal CT was unremarkable; so was the interrogation of the implantable cardiac defibrillator (ICD) device. Treatment with 10 mg of baclofen proved futile; however, the number of episodes decreased with the administration of 0.5 mg of clonazepam daily. On discharge, the patient was instructed to follow up at the neurology clinic with the intent to do EMG studies.
Discussion:
Diaphragmatic flutter (or diaphragmatic myoclonus) is a rare disorder characterized by rapid involuntary contractions of the diaphragm superimposed on ordinary respiratory excursions. As with any myoclonus, it must be triggered, in this case by either central or peripheral irritation to the phrenic nerve or unidiaphragm. About 50 cases have been reported in the literature with variable presentations. Epigastric pulsation is the commonest manifestation, but patients can also present with dyspnea, respiratory distress, hiccups, or belching. In most cases the diaphragmatic contractions are intermittent and may disappear during sleep, as found in our patient. These contractions are usually superimposed on a normal breathing pattern. Apnea was distinctly an unusual presentation of this syndrome. In this instance the phenomenon was likely triggered by misfiring of the ICD device or phrenic nerve irritation because of the saccular aortic aneurysm; the size of the latter favors the former theory. At this point an EMG study was indicated for a definite diagnosis. Hitherto, no standardized treatment approach has existed; however, case reports have shown a satisfactory response to benzo‐diazepines, phenytoin, carbamazepine, and haloperidol. In cases resistant to medical therapy, phrenic nerve block or transection has shown to be effective.
Conclusions:
We present this case to illustrate the rare but devastating clinical features of diaphragmatic myoclonus. Prompt recognition of this diagnosis by physicians can improve patient morbidity and reduce critical care resource utilization.
Disclosures:
D. Frackowiak ‐ none; K. Shaheen ‐ none