Rare Causes of Unilateral Vocal Fold Paralysis: Report of 3 Cases with Review of Literature

Abstract

Unilateral vocal fold paralysis is a common finding with a variety of underlying causes. The six main etiologic groups include neoplastic, traumatic (iatrogenic, accidental) neurological, inflammatory, congenital, and idiopathic. Various unusual causes have been described including foreign body ingestion, mediastinal lymph nodes, large pleural blebs, tracheal diverticulum, etc. It is therefore essential, that a thorough evaluation and methodical approach be undertaken to ascertain the etiology, before labelling it as idiopathic and offering any treatment. This review article focuses on the uncommon and rare causes of unilateral vocal fold paralysis that are presented through 3 representative case reports; a cardio-vocal (Ortner’s) syndrome, Zenker’s diverticulum and diffuse idiopathic skeletal hyperostosis. These examples are discussed with radiological findings in the context of current literature.

Introduction

Unilateral vocal fold paralysis is a common presentation to any voice clinic. The etiology may be attributed to multiple causes both within and outside the larynx. These may range from congenital, inflammatory, infective, endocrine, benign, and malignant laryngeal lesions to neurogenic, psychogenic, or iatrogenic causes. When no organic lesion is found in the neck, focus shifts to the skull base and mediastinum. Besides the common causes, the otolaryngologist needs to be aware of the rare clinical entities that may masquerade a life-threatening complication, if ignored.

We report 3 cases that presented to the Otolaryngology clinic for evaluation of hoarseness as the primary complaint and discuss each one of them.

Case 1

A 40-year old male presented with chief complaints of hoarseness for 4 months and a mild fever over the past 1 week. There was no associated dyspnea, dysphagia, or cough. The patient was a smoker and a diabetic for the last 4 years, controlled on oral hypoglycemic agents. The left vocal fold was seen to be immobile and in the paramedian position. The rest of the oral cavity and laryngopharynx was within normal limits. A contrast-enhanced computed tomography scan of skull base to the diaphragm revealed a contrast filled bilobed out-pouching from the inferior aspect of the arch of aorta, just at the origin of the left subclavian artery, measuring 4.5 * 2.5 cm with a neck of 3.0 cm impinging on the left pulmonary artery, suggestive of a saccular aortic arch aneurysm.

A CT angiogram revealed similar findings along with atherosclerosis of the walls of the arch of aorta (Fig. 1). Echocardiography was normal with 60% ejection fraction. There was also evidence of a fibro-cavitary area in the right upper lobe with surrounding segmental collapse and consolidation. Mild fluid was seen in the mediastinum posterior to the left atrium suggestive of mediastinitis. A bronchoalveolar lavage was performed which revealed evidence of tuberculosis thus the patient was started on anti-tubercular treatment. He was referred to the cardiology department where he refused any surgical intervention and was managed with antihypertensives and lipid-lowering agents.

Fig. 1.

CT Angiogram showing bilobed outpouching from the arch of aorta just at the origin of the left subclavian artery, extending slightly distally to involve the descending aorta

At one year follow up, the patient was stable, his voice had partially improved due to compensation by the opposite cord and he continues to be under cardiology surveillance.

Case 2

A 32-year old female presented with a history of change in voice over the last 2 days along with minimal discomfort in swallowing solid food. She also gave history of accidental ingestion of a semisolid medicine while chewing, followed by pain in the throat and foreign body sensation in the right side of the neck 2 months prior to this episode.

On clinical examination, the patient looked pale. No swelling or tenderness was noted in the neck. Flexible laryngoscopy was performed which showed right vocal fold paralysis.

A contrast-enhanced CT scan of neck (Fig. 2) and chest revealed a hyperdense non-enhancing lesion at the level of cricoid cartilage measuring 11*11 mm in size. A small outpouching from the right posterolateral wall of the esophagus, measuring 1.8*0.7 cm, was evident on barium swallow.

Fig. 2.

CECT neck showing hyperintense lesion at the level of cricoid cartilage

The patient was advised voice and swallowing therapy, along with dietary modifications.

Treatment options for a small zenker’s diverticulum and the risk of esophageal perforation were discussed. She opted for flexible oesophagoscopy with a suction clearance of impacted material and refused to undergo surgery.

At 6 months follow up, the patient was swallowing well and had no further episodes of impaction. The vocal fold paralysis recovered partially, and she had a reasonable voice due to compensation by the opposite cord.

Case 3

A 56-year-old male, smoker, presented with a history of hoarseness and pain in the neck that was progressively increasing over the last 6 months. There was no history of neck stiffness, dysphagia, or weakness in the upper limbs. Palpation of the anterior neck revealed marked tenderness in the thyrohyoid and cricothyroid spaces indicating signs of muscle tension dysphonia. Flexible laryngoscopy was difficult as the posterior pharyngeal wall was pushed forward making it difficult to negotiate the scope (Fig. 3a). The left vocal cord was fixed in paramedian position with right false cord hyperfunction and incomplete glottic closure (Fig. 3b, c).

Fig. 3.

a Difficult laryngeal exposure on flexible laryngoscopy, with posterior pharyngeal wall bulging anteriorly. b Vocal folds in abducted position. c Vocal folds in adducted position. Left vocal fold in paramedian position with incomplete glottic closure. d Computed tomographic scan of the patient, sagittal view, showing large osteophytes in the cervical spine

A CT scan from the skull base to diaphragm revealed new bone formation at C4-7 vertebrae with anterior fusion (Fig. 3d). Large osteophytes were protruding anteriorly and impinging upon the posterior wall of the pharynx causing narrowing and anterior displacement of the laryngopharynx. Flexion and extension of the cervical spine were normal. An orthopedic opinion was sought, and the patient was planned for an osteophytectectomy. Meanwhile, speech therapy was started to take care of the muscle tension component of dysphonia.

On 6 months follow up, the strain in his voice had improved remarkably and vocal fold function partially recovered.

Discussion

A literature search has revealed many unusual causes of vocal cord paralysis, including, vitamin B12 deficiency, lithium battery ingestion, neuroborreliosis, tubercular mediastinal lymphadenopathy, large pleural bleb, and tortuous esophagus, tracheocele [1] among others. It is interesting to note that some of these cases were labelled as idiopathic before being referred to the laryngologist for intervention.

Case 1

Nobert Ortner, in 1897, first described cardiovascular disease as the cause of unilateral vocal fold paralysis. He observed left recurrent laryngeal nerve palsy in 3 patients with severe mitral stenosis and dilated left atrium. Also known as cardio-vocal syndrome, it encompasses all the anatomical cardiovascular lesions be it congenital, infective, inflammatory, iatrogenic, or traumatic. Ortner’s syndrome is more common in males and the age group ranges from 2 months to 87 years.

This syndrome has mainly been described in relation to the left recurrent laryngeal nerve owing to its long course in the mediastinum and compression by lesions extending into the aortopulmonary window.

Besides hoarseness, other symptoms include dysphagia, which may be due to aspiration or direct compression of the esophagus by the dilated atrium, dyspnea on exertion and chest pain. Though pediatric cases are rare they may present with failure to thrive along with hoarseness.

The most common cardiac cause is a mycotic aneurysm followed by an atherosclerotic aneurysm. This is seen either in the distal part of the arch of aorta or the proximal part of the descending aorta. The other cardiac anomalies described are mitral stenosis with left atrial enlargement and mitral regurgitation, pulmonary artery dilatation due to primary or secondary pulmonary artery hypertension [2], hematoma of the aortic arch [3], aortic dissection [4], aneurysm of the ductus arteriosus [5]. Other rare causes include penetrating aortic ulcer [6], giant cell arteritis and anomalous left carotid artery [7] etc.

Hoarseness can be the only presenting symptom through the entire course of the disease and a life-threatening condition such as a painless aortic dissection or impending aortic rupture may remain unsuspected until the patient presents to the emergency. As in the case discussed, the patient’s only complaint was hoarseness, even though he had evidence of tuberculosis with mediastinitis and the aortic aneurysm had increased to a considerable size.

The treatment options for an aortic aneurysm are open aneurysmectomy, extra-anatomic bypass grafting, or endovascular grafting. Forty percent of patients recover their voice post-intervention if diagnosed early, while hoarseness may persist in others due to prolonged periods of compression. The recovery of hoarseness is better when patients undergo interventional therapy rather than surgery.

Case 2

The cause of a cricopharyngeal diverticulum remains unclear; however, it appears to involve dysfunction or incoordination of the upper oesophageal sphincter. Impaction of food or foreign bodies such as dental implants in Zenker’s diverticulum, has been noted in the past but presentation as a recurrent laryngeal nerve palsy is rare. Additional symptoms include regurgitation of undigested food, halitosis, and frequent episodes of aspiration.

Recurrent laryngeal nerve paralysis can be explained by peri-oesophageal inflammation caused by the undigested food, which can lead to perineural inflammation and involvement of the nerve. The development of vocal cord paralysis may indicate an impending perforation or fistulization of the oesophagus, thus warranting prompt evaluation. This paralysis may persist despite surgical removal of the impacted foreign body. In addition, the presence of a tracheoesophageal fistula can increase the chances of aspiration in such patients.

A plain x-ray usually fails to pick up a radiolucent foreign body hiding in the diverticulum and an oral contrast study may not be possible if the patient is aspirating. If flexible laryngoscopy fails to find a cause, a detailed inspection of the esophagus must be done with flexible esophagoscopy to avoid delaying the diagnosis [8].

Immediate removal of this retained foreign material and timely surgical intervention alleviates the symptoms and helps to prevent aspiration, pneumonia, and oesophageal perforation.

Case 3

Diffuse idiopathic skeletal hyperostosis (DISH), also known as Forestier’s disease, is a rheumatologic condition characterized by ossification of the anterior longitudinal ligament and anterior osteophyte formation along the spinal column. It mostly occurs in patients between the ages of 60–80 years and is usually asymptomatic. It presents to the otolaryngologist with symptoms of dysphagia (up to 6%), dysphonia (unilateral or bilateral vocal fold paralysis) or dyspnea, that is not responding to oxygen and bronchodilators. It is generally accepted that osteophytes larger than 12 mm become symptomatic [9].

Respiratory symptoms are caused by osteophytes at C2, C3, C4 level compressing the posterior pharyngeal wall and larynx. Chondritis and ankylosis of the cricoarytenoid joint can further lead to vocal cord paralysis. Retro-cricoid inflammation and edema, and infection of the recurrent nerve itself, often necessitates a tracheostomy.

Dysphagia occurs due to ventral osteophytes in the lower cervical vertebrae C3, C4, C5, and C6 leading to localized inflammation and ulceration of the pharyngeal wall, neuropathy, or limited movements of the laryngopharynx. Often the probability of malignancy scores over DISH, in the elderly male smoker, who presents with hoarseness and dysphagia keeping the diagnosis in abeyance for several months. In our patient, though the lower cervical vertebrae were involved, there was no complaint of dysphagia and hence a swallowing evaluation was not done.

DISH is often diagnosed incidentally on cervical computed tomography and X-ray examinations.

Investigations in the form of laryngoscopy, video fluoroscopy and barium swallow, can aid to find the cause of hoarseness and the potential site of mechanical obstruction. Visualization of the larynx may be extremely difficult in some cases as the posterior pharyngeal wall is often pushed forward by the osteophytes, making it difficult to negotiate the flexible scope close to the cords. Electromyography of the glottis may serve to further characterize neurologic manifestations of DISH and differentiate between a neurological and mechanical cause.

DISH may often be confused with other degenerative changes of the cervical spine seen in the elderly population. A “wax dripping down the candle” appearance is very suggestive of DISH, whereas “candle flame hyperostosis” is suggestive of other degenerative causes [9].

The initial treatment of cervical DISH is typically conservative, limited to the use of anti-inflammatory medication, steroids, muscle relaxants, and swallowing therapy. Surgery should be considered when conservative management fails and/or in case of severe dysphagia or respiratory compromise.

Intubation for general anaesthesia may be challenging because of distorted laryngeal anatomy. Awake fibreoptic examination and intubation are proposed in these patients. Common surgical management includes anterior cervical osteophytectomy alone, or subsequent anterior cervical fusion, if instability results [10]. Many authors have reported recovery of nerve function after surgery.

The otolaryngologist should be aware and needs to include DISH in the armamentarium of cases who present with vocal cord paralysis alone, or with dysphagia, and aspiration as effective and directed therapy can help many patients.

Conclusion

Unilateral vocal fold paralysis can be the only sign masquerading a serious underlying condition. A high index of suspicion, examination by an experienced otolaryngologist and interprofessional teamwork including radiologists, is essential to guide the diagnosis and avoid a devastating complication. It is imperative to actively seek the cause of vocal fold paralysis, before labelling it as “idiopathic” and offering the patient a permanent medialisation procedure. Often, the paralysis improves once the underlying condition is treated.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Informed consent

Written informed consent for publication of their clinical details and/or clinical images was obtained from the patients. A copy of the consent form is available for review by the editor of this journal.