|Year : 2014 | Volume
| Issue : 2 | Page : 58-62
Etiological profile of unilateral vocal cord paralysis: A single institutional experience over 10 years
Sachin Gandhi, Sheetal Rai, Nilanjan Bhowmick
Departments of Laryngology, Deenanath Mangeshkar Hospital and Research Centre, Pune, Maharashtra, India
|Date of Web Publication||21-May-2015|
Dr. Nilanjan Bhowmick
Department of Laryngology, Deenanath Mangeshkar Hospital and Research Centre, Erandwane, Pune - 411 004, Maharashtra
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objective: Unilateral vocal cord palsy is a major cause of dysphonia. With umpteen number of causes being attributed to it and changing trends in etiology from place-to-place and over time, it is of utmost importance to arrive at a correct diagnosis to plan further management and to determine the prognosis. The aim was to evaluate the etiological profile of unilateral vocal cord palsy in our institute that is a tertiary referral center over the past 10 years. Materials and Methods: Case records of all patients diagnosed with unilateral vocal cord palsy who presented to Deenanath Mangeshkar Hospital, Pune, Maharashtra, India between 2003 and 2013 were retrospectively reviewed. The exclusion criteria included patients with laryngeal/hypopharyngeal malignancies, intubation trauma, congenital vocal cord palsy and cricoarytenoid joint ankylosis. The age, gender, laterality and etiology were the factors taken into consideration. Results: A total of 277 cases spanning over the age range of 2 months to 98 years met our inclusion criteria, out of which 179 were males, and 98 were females with a male to female ratio being 1.82:1. In terms of laterality, 182 patients had left sided, and 95 had right sided vocal cord palsy. Majority of the cases were found to be in the fourth and fifth decades. The most common etiology was idiopathic 136 (49.1%). The incidence of various other etiologies were surgical trauma 60 (21.6%), nonsurgical trauma 10 (3.7%), nonlaryngeal malignancy 36 (12.9%), central/neurological 17 (6.1%), postradiation 1 (0.3%), and other benign lesions 17 (6.1%). Among the surgical causes, the incidence of nonthyroidectomy surgeries (58.3%) was more than that of thyroidectomy (41.6%). Thyroidectomy was the single most common surgical cause for unilateral vocal cord palsy, followed by other nonthyroid neck surgeries (20%) and anterior cervical decompression (18.3%). Conclusion: The most common cause for unilateral vocal cord palsy is idiopathic. Nevertheless it is still an important sign of various underlying diseases. A thorough evaluation which must necessarily include a computerized tomographic scan from base of the skull to upper mediastinum is essential before labeling a case as idiopathic; hence, also the need for extended follow-up of the cases to avoid misdiagnosis of any underlying subclinical malignancy.
Keywords: Etiology, iatrogenic, unilateral, vocal cord palsy
|How to cite this article:|
Gandhi S, Rai S, Bhowmick N. Etiological profile of unilateral vocal cord paralysis: A single institutional experience over 10 years. J Laryngol Voice 2014;4:58-62
| Introduction|| |
Unilateral vocal cord palsy is a relatively common finding at a voice clinic. It may be asymptomatic or may present with dysphonia or even dysphagia and aspiration. Most cases do not present to the voice clinic either due to spontaneous recovery or due to compensation by the opposite cord. Many more are underdiagnosed due to lack of farsight on behalf of the surgeon to subject the postoperative cases for a laryngological evaluation. Due to reasons more than one, the exact incidence of the etiology behind unilateral vocal cord palsy has remained a mystery difficult to unfold.
Literature review has revealed that the most common etiologies of unilateral vocal cord palsy have shown variation in both time and geographic location. Kearsley reported lung carcinoma as the number one cause of vocal cord palsy in an Australian study.  In another Australian study conducted 18 years later, Havas et al. demonstrated that iatrogenic causes such as surgery had replaced malignancy as the most common etiology.  Rosenthal et al. found in their study, a shift in the major etiology from extralaryngeal malignancies to nonthyroid surgical procedures.  Another recent study conducted in Tokyo by Takano et al., a retrospective review of etiology over 45 years, showed that the surgery was the major cause of unilateral vocal cord palsy with thyroidectomy leading the group.  There have been very few studies on unilateral vocal cord palsy from the Indian subcontinent over the past three decades. Our study attempts to evaluate the etiological profile of unilateral vocal cord palsy over the past 10 years in our institute that is a tertiary referral center.
| Materials and Methods|| |
The present study was conducted at the Department of ENT and Laryngology at Deenanath Mangeshkar Hospital, Pune, Maharashtra, India, which is a tertiary referral center between January 2003 and December 2013. A retrospective review of the case records of all patients diagnosed with unilateral vocal cord palsy who presented to us was carried out. Patients with laryngeal/hypopharyngeal malignancies, intubation trauma, congenital vocal cord palsy and cricoarytenoid joint ankylosis were excluded from the study. A total of 277 cases who met the inclusion criteria were considered. There were 179 males and 98 females with age ranging from 2 months to 98 years. Patient data with regard to age, gender, duration of symptoms, laterality, medical and surgical history and imaging studies were reviewed.
The patient workup included a detailed history taking, physical examination, flexible fiberoptic and stroboscopic evaluation of the larynx and imaging by computerized tomographic (CT) scan from the skull base to upper mediastinum when no obvious etiology was found. Fine needle aspiration cytology, CT brain/chest and barium swallow were done depending on the clinical suspicion. A diagnosis of idiopathic unilateral vocal cord palsy was made when the clinical and radiological examinations were normal.
| Results|| |
We studied a total of 277 cases that fulfilled our inclusion criteria. Out of this, 179 were males, and 98 were females. The male to female ratio was 1.82:1. Left sided vocal palsy was more common than the right. We had 182 patients with left sided palsy and 95 patients with right sided palsy. The age range of the patients varied from 2 months to 98 years (mean age - 48.07 years).
No obvious etiology was found after thorough investigations in 136 cases. This group that formed the majority was labeled as idiopathic (49.1%). Out of the remaining 141 cases where the cause was identified, surgical trauma (iatrogenic) was found to be the most common etiological factor (21.6%). The surgical etiology was divided into head, neck and thoracic procedures [Table 1]. The other causes included nonsurgical, that is, external neck trauma (3.7%), nonlaryngeal malignancy (12.9%), central/neurological (6.1%), postradiotherapy (0.3%) and other benign lesions (6.1%) [Figure 1].
Under the iatrogenic category, the incidence of all nonthyroidectomy surgeries together (58.3%) was more than thyroidectomy (41.6%). Thyroidectomy was still the single most common surgical cause for unilateral vocal cord palsy, followed by other nonthyroid neck surgeries and anterior cervical decompression.
The nonthyroidectomy group included other neck surgeries (20%), anterior cervical decompression (18.3%), thoracic surgeries (8.3%), cardiac surgery (6.6%) and neurosurgery (5%). The nonthyroid neck surgeries included: Supraclavicular lymph node excision (n = 4), parapharyngeal tumor excision (n = 6), radical neck dissection (n = 2). Of the 6 parapharyngeal tumors excised, 2 were glomus jugular tumors, 2 were vagal schwannomas, one was a carotid body tumor and another one was a neurofibroma arising from the cervical sympathetic chain.
The thoracic surgeries included five cases: Pulmonectomy (n = 1), thoracotomy and pericardiocentesis (n = 1), mediastinal thymoma excision (n = 1), esophagectomy and gastric pull up (n = 1) and breast lump excision (n = 1). The cardiac surgeries included four cases: Surgical repair of tetralogy of Fallot (n = 1), patent ductus arteriosus (PDA) ligation (n = 2) and implantation of vagus nerve stimulator for ischemic cardiomyopathy (n = 1). There were three neurosurgery cases in our study that included foramen magnum decompression (n = 2) and ligation of intracranial aneurysm (n = 1).
The nonlaryngeal malignancies accounted for 12.9% (n = 36) of the cases which included esophageal carcinoma (n = 12), lung carcinoma (n = 10), breast carcinoma (n = 5), non-Hodgkin's lymphoma (n = 4), Hodgkin's lymphoma (n = 1), metastatic neck nodes (n = 3) and nasopharyngeal carcinoma (n = 1). Among the 12 cases of esophageal malignancy, there were 2 cases who showed only cervical lymphadenopathy on CT scan and on esophagoscopy, were revealed to have growth in upper esophagus.
Central or neurological etiology was identified in 17 cases, out of which we had one case of motor neuron disease, one case of myasthenia gravis, 3 cases of the postviral neuritis and 12 cases of cerebrovascular accident (CVA). The other benign lesions accounted for 17 cases, which included pulmonary tuberculosis (n = 10), colloid cyst of the thyroid (n = 1), cardiac anomalies such as coarctation of aorta (n = 1), tetralogy of Fallot (n = 1), right ventricular hypertrophy secondary to pulmonary hypertension (n = 1), left ventricular hypertrophy (n = 1), abnormal variant of azygous system (n = 1) and enlarged prevascular lymph node (n = 1).
| Discussion|| |
Unilateral vocal cord palsy is a common presentation at an Otolaryngology clinic. Western literature has revealed a great deal of information on the etiology of unilateral vocal cord palsy. Our attempt was to throw light on the Indian scenario in this regard.
Several causes have been attributed to recurrent laryngeal nerve injury including iatrogenic or noniatrogenic trauma, neurologic disease, tumor infiltration or compression, infection, collagen-vascular disease, or idiopathic cause. This event may occur with or without concomitant superior laryngeal nerve injury, depending on the cause and site of the lesion. The recurrent laryngeal nerve is at risk for injury during many surgical procedures, such as thyroid, anterior cervical spine, and thoracic surgery. Mechanisms of iatrogenic injury include intubation, transection, crush, traction, inadvertent ligature placement, and thermal injury. 
Several neurologic diseases are known to affect vocal fold movement, including multiple sclerosis, amyotrophic lateral sclerosis, syringomyelia, myasthenia gravis, Guillain-Barre and Parkinson's disease. CVAs may result in injury to recurrent laryngeal nerve neurons, but typically other neurons are also affected. Central nervous system tumors, such as gliomas and diabetic recurrent laryngeal nerve neuropathy are other causes. More unusual causes include disorders such as Gerhard syndrome, laryngeal abductor paralysis that may be familial (autosomal dominant, autosomal recessive or X-linked inheritance and with adult onset) or acquired secondary to bulbar lesions or neurodegenerative disease. Aggressive thyroid malignancies may invade and injure the recurrent laryngeal nerve. Compression by large goiters, benign neoplasms, and nonthyroid malignancies, such as the classic Pancoast tumor of the left upper lung may also involve the nerve. 
Idiopathic vocal fold paralysis is not well understood. Some suspect a viral cause, because many patients report an upper respiratory infection before the onset of vocal symptoms. There are several infectious causes that have been reported to cause recurrent laryngeal nerve paralysis, such as Lyme's disease, tertiary syphilis, Epstein-Barr virus (EBV), and herpes. Other causes of recurrent laryngeal nerve injury reported include systemic lupus erythematosus, PDA, mediastinal radiation, iodine 131 therapy, amyloidosis, Charcot-Marie-Tooth disease More Details, mitochondrial disorders, porphyrias, polyarteritis nodosa, silicosis and familial hypokalemic periodic paralysis. 
Clinically, unilateral vocal cord palsy presents as breathy voice. Nevertheless patients may also present with various other symptoms such as dysphonia, aspiration and dysphagia. Compensation by the opposite cord, occurring after a few weeks, further improves the vocal quality and aspiration. Should reinnervation occur, typically it may not be detectable initially. The clinical course following reinnervation is determined by the degree of reinnervation and synkinesis.
Our study had patients with age ranging from 2 months to 98 years (mean age - 48.07 years). The incidence of unilateral vocal cord palsy was found to increase with age, the peak incidence being around the fourth and fifth decade. Jaya Gupta et al. have reported the peak incidence around the fifth decade in their study.  The incidence of congenital cardiac diseases and cardiothoracic surgery for the same was more in the first and second decade. Cases of idiopathic vocal cord palsy were found to be clustered around the third to sixth decade with a peak incidence around the fourth and fifth decade. The neurologic causes mainly cerebrovascular stroke were more common in the elderly age group. Cases of surgical trauma and nonlaryngeal malignancies were clustered around the third, fourth and fifth decade.
The males outnumbered the females with a male to female ratio of 1.82:1. The male preponderance in our country is probably due to a higher prevalence of smoking among men. Moreover, with an increase in the incidence of laryngeal cancer, there is an increasing awareness in this regard. This has been instrumental in the early presentation to ENT clinics. Left sided vocal cord palsy was seen in 65.7% of the cases. This supports the fact that the left recurrent laryngeal nerve is more susceptible to injury due to its longer course through the chest.
The advancement in diagnostic modalities like CT and magnetic resonance imaging have brought many hidden etiologies to light but nevertheless, we found in our study that the incidence of idiopathic cases (49%) was clearly the highest among all other causes, unlike many other studies. , Surgical trauma (21.6%) was found to be the second most common etiology in our study. The others were nonsurgical trauma (3.7%), nonlaryngeal malignancy (12.9%), central/neurological (6.1%), postradiation (0.3%), and other benign lesions (6.1%).
Among the surgical causes, the incidence of nonthyroidectomy surgeries (58.3%) was more than that of thyroidectomy (41.6%). Thyroidectomy is still the single most common surgical cause for unilateral vocal cord palsy, followed by other nonthyroid neck surgeries (20%) and anterior cervical decompression (18.3%). Following anterior cervical decompression and fusion, the recurrent laryngeal nerve may get involved as a result of direct surgical trauma, division of the nerve, pressure or stretch-induced neuropraxia and endotracheal tube related vocal fold palsy.  Due to its more lateral placement and oblique course, the right recurrent laryngeal nerve is vulnerable to injury secondary to central venous catheter placement and median sternotomy (during which the subclavian artery is under lateral retraction). The left recurrent laryngeal nerve is particularly at risk during left upper lobectomy or cardiac surgery.
Nonlaryngeal malignancy contributed to 12.9% of the cases in our study. Another study by Ko et al. found a 12% incidence of nonlaryngeal malignancy. In our study, carcinoma esophagus (n = 12) was the most common malignancy associated with unilateral vocal cord palsy, followed by carcinoma lung (n = 10). This was contrary to many other previous studies where lung carcinoma was found to be the most common malignancy to cause unilateral vocal cord paralysis. ,
Among the neurological cases, CVA (n = 12) was found to be the most common etiology. We also had one case each of motor neurone disease and myasthenia gravis. Viral neuritis was considered as a separate entity. These cases presented with fever with upper respiratory tract infection prior to developing unilateral cord palsy. Neurological examination in these patients was normal except for the cord palsy. However, there are case reports that suggest a definite relationship between recurrent laryngeal neuropathy and EBV, herpes simplex and varicella zoster. ,
The other benign lesions accounting for vocal cord palsy in our study included pulmonary tuberculosis, colloid cyst of the thyroid, cardiac anomalies like the coarctation of the aorta, tetralogy of Fallot, right ventricular hypertrophy secondary to pulmonary hypertension, abnormal variant of azygous system and enlarged prevascular lymph node. In this category, pulmonary tuberculosis accounted for the majority of the cases. In chronic pulmonary disease, paralysis may be caused by three possible mechanisms that exert effects on the nerve: (1) The nerve may be passing through or may be adjacent to a mass of caseating nodes, (2) the nerve may be trapped in the dense fibrous pleural thickening or in the chronic fibrosing mediastinitis that may occur, and (3) the nerve may be stretched due to retraction of the left upper lobe bronchus pulled towards the apex.  Hoarseness due to left recurrent laryngeal nerve paralysis caused by an identifiable cardiovascular disease is referred to as Ortner syndrome. It was first described in a patient with severe mitral valve stenosis by Ortner in 1897. Left atrial enlargement can compress or stretch the nerve. Other causes of Ortner syndrome include mitral valve prolapse, aortic aneurysm, and septal defects. 
All our patients were subjected to CT scan from the skull base to mediastinum. CT not only helps in early detection of the primary malignancy, but is also useful to know the progression of malignancy between follow-ups. It can also reveal various nonmalignant causes of vocal cord palsy. CT can more accurately detect the extent and location of the responsible pathology than a chest radiograph in a patient presenting with vocal cord palsy. According to Song et al., most primary diseases in the chest can be detected when neck CT scans are taken for patients with right vocal cord palsy, including an area of the skull base to the thoracic inlet, and for left vocal cord palsy, including the area up to the aortic triangle. Therefore, it would be cost-effective to scan down to the level of the aortic triangle when taking neck CT scans for patients with vocal cord palsy, regardless of the paralytic side. 
| Conclusion|| |
The most common cause of unilateral vocal cord palsy is idiopathic; nevertheless vocal cord palsy is a very important sign of various underlying diseases. A thorough evaluation, which must necessarily include CT neck and mediastinum, and diagnostic endoscopy when called for is essential before labeling a case as idiopathic. So also the need for extended follow-up of these cases to avoid misdiagnosis of any underlying subclinical malignancy.
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