Immobile vocal fold secondary to thyroid abscess: A case report.

Abstract

Vocal fold paralysis as a result of a thyroid abscess is extremely rare. In this article, we report only the second documented case of such a finding. The paralysis was discovered after our patient, a 40-year-old woman, had come to the office with a complaint of discomfort in the right lower neck. Computed tomography confirmed the presence of an abscess in the posterior thyroid gland. Fine-needle aspiration did not identify any inflammatory or suspicious cells. The abscess was treated with hemithyroidectomy, and the paralysis resolved 3 weeks later. There has been no recurrence after 4 years.

Introduction

Cases of acute suppurative thyroiditis that lead to a primary thyroid abscess are rare. Several factors contribute to the thyroid's resistance to invading organisms. First, the gland is completely encapsulated by fibrous tissue and enclosed in split fascial planes. Second, based on its weight, the amount of the thyroid's vascular supply and lymphatic drainage is greater than that of any other organ. Finally, the presence of iodine is believed to inhibit bacterial proliferation. [1,2]

When infection does occur, the most likely routes are through the bloodstream, lymphatic system, and internal fistulae (e.g., pyriform sinus fistulae or patent thyroglossal duct cysts). [3-5] The clinical presentation is often sudden. Some patients have a recent history of upper respiratory infection. In many cases, a nonspecific prodrome progresses to fever, localized tenderness, erythema, and swelling. Patients sometimes complain of dysphagia or odynophagia. [2,6] Hoarseness is rare.

In this article, we describe the case of a patient with a thyroid abscess that eventually led to vocal fold paralysis.

Case report

A previously healthy 40-year-old woman came to the office with a complaint of pain in the right lower neck that had been present for approximately 2 weeks. She experienced dysphagia/aspiration with thin liquids. She denied weight loss, stridor, and fever, and she had not traveled recently. Her medical history was significant for mild asthma, which was controlled with inhaled medications. She smoked less than one pack of cigarettes per day, and she drank alcohol only occasionally. When she was a child, she had undergone radiation therapy for the treatment of a breast mass. Her initial physical examination was unremarkable except for a slight tenderness near the right lobe of the thyroid.

The woman continued to experience discomfort during the following week, and when she returned for a followup visit, she was aphonic. Fiberoptic laryngoscopy revealed that her right vocal fold was immobile. Computed tomography (CT) demonstrated the presence of a 2.5 x 2.l x 2.0-cm solid mass contiguous with the posterior aspect of the right thyroid lobe (figure). She was referred for ahead and neck evaluation and possible treatment of her thyroid mass. Fine-needle aspiration cytology showed the presence of a dense colloid substance, but no malignant cells. Because her mass was associated with an immobile vocal fold, the decision was made to perform a right hemithyroidectomy.

Preoperatively, the patient's temperature was 98.90[degrees] F. She continued to experience mild tenderness in the lower right portion of the thyroid. Her hemoglobin level was 13 g/dl, her white blood cell count was 5.8 x [10.sup.9]/L (57% neutrophils, 32% lymphocytes, 7% monocytes, 3.3% eosinophils, and 0.7% basophils), her platelet count was 374x [10.sup.9]/L, and her prothrombin time was 11.9 seconds.

Introperatively, a large cystic mass was found in the right thyroid. The mass was plunging toward the rear of the larynx, and it had deviated the trachea toward the left. The lesion was identified as a thyroid abscess.

Gram's stains and acid-fast bacilli smears taken from the abscess were negative. Bacterial, mycobacterial, and fungal cultures all failed to grow any organisms. Histopathologic evaluation of the mass revealed the presence of granulation tissue and acute inflammatory cells. Necrotic material was found in the cavity of the mass. No malignancy was identified.

The patient recovered without complication and was discharged the following day. Three weeks after surgery, her vocal fold mobility had returned and her voice was again normal. She has remained free of disease for 4 years.

Discussion

Patients with thyroid abscess rarely experience hoarseness. This is only the second known case of a thyroid abscess causing reversible unilateral vocal fold paralysis.

In addition to abscess, the differential diagnosis of a thyroid mass includes Hashimoto's thyroiditis, subacute thyroiditis, acute suppurative thyroiditis, a solitary nodule, a thyroglossal duct cyst, a dissecting retropharyngeal abscess, a thyroid cyst, and thyroid carcinoma or adenoma. [2] Various organisms have been cultured from thyroid abscess cavities, the most common being group A beta-hemolytic streptococci, staphylococci, and pneumococci. Other reported pathogens are mycobacteria, fungi, Pneumocystis carinii, Escherichia coli, and Salmonella typhimurium. When the latter two bacteria are found in thyroid abscesses, they are believed to arise from transient bacteremia from distant sources. [6,7] A delay in diagnosis can lead to complications such as septicemia, retropharyngeal abscess, tracheal or esophageal rupture, or internal jugular vein thrombosis.

The acquired causes of vocal fold immobility include trauma, inflammation, and infection, notably syphilis and tuberculosis. Boyd et al reported a case of impaired mobility in a patient with an acute anaerobic abscess of the thyroid. [8]

CT is essential in making the diagnosis. On thyroid CT, an area of decreased uptake might be evident near the abscess. [9] Fine-needle aspiration can be helpful diagnostically as well as therapeutically.

Proper management includes at least a hemithyroidectomy followed by appropriate antibiotic therapy. Identification and isolation of the recurrent nerve is indicated in this procedure. It is advisable to remove the lobe to obtain pathologic confirmation and tissue cultures and to rule out secondary lesions. Boyd et al have advocated that the abscess merely be incised and drained in order to avoid removing a thyroid from an already inflamed thyroidal bed. [8] One disadvantage of this procedure is that it leaves the thyroid in a field with altered tissue planes. Also, if another procedure were to become necessary, the risk of complication would rise.

In our case, the vocal fold immobility was most likely secondary to a neuropraxia that arose when the abscess compressed the recurrent laryngeal nerve. Inflammatory neuritis might have been a contributing factor. [8] It is possible that the cricoarytenoid joint was inflamed, but this is not likely in light of the lack of findings on the laryngeal examination.

References

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(4.) Miyauchi A, Matsuzuka F, Kuma K, Takai S. Pyriform sinus fistula: An underlying abnormality common in patients with acute suppurative thyroiditis. World J Surg 1990;14:400-5.

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(9.) Bernard PJ, Som PM, Urken ML, et al. The CT findings of acute thyroiditis and acute suppurative thyroiditis. Otolaryngol Head Neck Surg 1988;99:489-93.