Letters to the Editor
Case Report: Expanding the Differential Diagnosis of Intractable Cough
Am Fam Physician. 2005 Nov 15;72(10):1975.
TO THE EDITOR: We present a patient with an unusual cause for persistent debilitating cough, which adds to the myriad differential diagnoses of chronic cough.
A 43-year-old male factory worker presented with a four-month history of persistent, dry, debilitating cough (exacerbated by perfumes and other strong odors) and progressive hoarseness. The cough was so frequent and severe that he was forced to stop working. He also complained of episodic “heartburn.” He had a 10 pack-year history of smoking but had stopped four years previously. He did not use alcohol. His allergies to house dust and dog dander were treated with antihistamines, and he had no history of asthma. A tympanomastoidectomy had been performed 14 years previously for chronic otitis media. A ventilating tube was inserted into the left tympanic membrane four months before presentation in our office. He had received treatment from a pulmonologist with inhaled and oral corticosteroids, neither of which provided relief. Pulmonary function tests, chest radiograph, computed tomography of the lungs and sinuses, and bronchoscopy with washings were negative. Despite a negative pH probe study, he was started on omeprazole (Prilosec) for presumed gastroesophageal reflux.
During examination in our otolaryngology office, the patient had a dry, nonproductive, hacking cough. His nose, pharynx, and larynx were normal. Examination of the left ear identified a plastic pressure equalization ventilation tube deep (medial) in the external auditory canal.
On a follow-up visit three weeks later, he stated that his cough had ceased completely one week previously. The clinical examination was again unremarkable, except that the pressure equalization tube was now positioned laterally in the external auditory canal and was removed easily. On further questioning, he recalled that his cough began immediately after placement of the tube.
We concluded that his intractable cough was caused by the ventilation tube either through or on the surface of the tympanic membrane, presumably with persistent stimulation of a branch of the vagus nerve.
Ventilation tubes have been placed through the tympanic membrane since the 1950s for aeration of the diseased middle ear. Tens of millions of tympanostomy tubes have been placed worldwide in children and adults, without cough being a frequently associated complication. We found only one reported case of a ventilating tube causing similar symptoms.1
The sensory nerve supply of the epithelium of the external auditory canal is via branches of the trigeminal, facial, glossopharyngeal, and vagus nerves. Arnold’s nerve is the auricular branch of the vagus nerve that innervates the deep external auditory canal and courses over the medial wall of the middle ear (the promontory). Stimulation of Arnold’s nerve incites the cough reflex that sometimes occurs with manipulation of the medial external auditory canal.2 Why the presence of ventilating tubes through the tympanic membrane does not cause coughing in the majority of patients remains a mystery.
This case demonstrates that in patients with recalcitrant cough unresponsive to appropriate treatment, otoscopic examination and removal of any foreign material from the external auditory canal is worth trying before more invasive investigations are conducted.
1. Feldman JI, Woodworth WF. Cause for intractable chronic cough: Arnold’s nerve. Arch Otolaryngol Head Neck Surg. 1993;119:1042.
2. Hollinshead WH. Anatomy for surgeons: the head and neck. 3d ed. Philadelphia: Harper & Row, 1982.
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