Bamboo Nodes of Vocal Folds: A Description of 10 Cases and Review of the Literature

Autoimmune diseases cause multisystem damage, including the larynx. The most frequently described laryngeal lesions associated with autoimmune diseases are tissue ulceration, edema, cricoarytenoid arthritis, laryngeal paralysis, and bamboo nodes in vocal folds [1]. Bamboo nodes are autoimmune disease-specific lesions, but their pathophysiological mechanisms are still not fully understood.

In 1959, Scarpelli et al. [2] described a case of systemic lupus erythematosus (SLE) with severe laryngeal edema that led to the patient’s death. Microscopic examination revealed extensive edema of the lamina propria, with tissues invaded by numerous histiocytes, lymphocytes, plasma, and mast cells. The lesions were initially named “inflammatory nodules.” In 1972, Webb and Payne [3] were the first to report lesions of the vocal folds characteristic of rheumatoid nodules in a 48-year-old woman with a diagnosis of rheumatoid arthritis (RA) who complained of hoarseness. Laryngoscopy revealed a nodule in each vocal fold “unlike any previously seen.” The microscopic examination described several small nodules in the submucosa, each consisting of a fibrinoid necrosis surrounded by palisading histiocytes. In 1975, Friedman [4] described 2 cases of laryngeal submucosal lesions and postulated that they were autoimmune complex deposits in the vocal fold.

In 1993, Hosako et al. [5] reported submucosal lesions in the middle third of vocal folds in a patient diagnosed with SLE and observed a similarity with the nodes of a bamboo stem, hence their proposal to change their name from “rheumatoid nodules” to “bamboo nodes.” In 2001, Perouse et al. [6] described 19 cases of bamboo nodes and provided details on their specific ovoid swollen aspect, including the fact that they can be isolated or multiple. They noted that all 19 patients had been diagnosed with an associated autoimmune disease and concluded that an autoimmune disease should be searched for each time when bamboo nodes are observed at laryngeal examination. Treatment and voice quality were not studied in detail.

In studies published so far, morphologic characteristics of bamboo nodes have been described in detail, including their form, their position and their evolution after surgical or conservative treatment but study of voice quality over time has been left in the background. Schwemmle and Ptok [7] described a case report of a 43-year-old woman with a “rough, breathy and unstable” voice. Only phonation time was measured before and after treatment without GRBAS (Grade, Roughness, Breathiness, Asthenia, Strain) scale evaluation. Murano et al. [8] and Perouse et al. [6] described bamboo nodes as lesions associated with dysphonia without detailing the acoustic characteristics. Hilgert et al. [9] performed a voice analysis including a perceptual assessment with a simplified version of the GRBAS scale. Pure tone audiometry was also performed but the cohort of patients was restricted including only 3 patients.

We performed a retrospective review of our clinical experience of 10 cases of bamboo nodes. We focused on the treatments that benefited our patients and analyzed not only the evolution of the vocal fold lesions, but also the quality of the objective and subjective voice. Our objective was to determine which therapy is most appropriate in achieving good quality of voice, knowing that this is the main parameter for the patient.

We finally conducted a systematic review of the scientific literature on bamboo nodes in order to better understand their clinical manifestations and compare our results to those published until now.

We performed a retrospective clinical study of 10 patients with bamboo nodes who presented to the Otorhinolaryngology Departments at Geneva and Lausanne University Hospitals (Switzerland) from 2008 to 2013. The diagnosis was made by videostroboscopy by 2 experienced laryngologists. Patient data regarding sex, age at diagnosis, occupation, symptoms, associated autoimmune disorder, medical follow-up, and type of treatment were collected. For all patients who have had speech therapy, we specified the duration of treatment. We described voice quality by the initial and final GRBAS scale. The GRBAS scale was filled in by 2 experienced clinicians: Dr. Valerie Schweizer for patients seen in Lausanne and Dr. Igor Leuchter for patients who consulted in Geneva. For 3 patients, the initial or final GRBAS scale was missing in the file. Vocal recordings were listened to retrospectively and the GRBAS scale was determined by Dr. Schweizer, Dr. Leuchter, and Dr. Todic. The vocal evaluation was made according to the standard GRBAS criteria regularly used in our clinic. The 2 physicians who evaluated these patients were trained practitioners with high ability to hear vocal nuances and score them.

We then conducted a PubMed/Medline search of all articles published within the date range of 1972–2015 without language restriction using the keywords “bamboo nodes,” “laryngeal autoimmune lesions,” “connective tissue disease and hoarseness,” and “rheumatoid nodules.” The titles and abstracts of retrieved references were screened for potentially relevant studies. The full text of all articles in English, French, and German containing a clear clinical description of laryngeal lesions and a microscopic analysis of the lesions were obtained and reviewed independently by 2 reviewers. Duplicate studies were excluded. The study protocol was accepted by the institutional ethics committee of the Geneva University Hospitals for both parts of the study.

All patients were women aged from 18 to 62 years (mean: 37 years) living in the region of Lausanne and Geneva. The first and most frequent symptom was hoarseness. Other symptoms included arthralgia, asthenia, dyspnea, and dysphagia. Seven out of 10 patients use their voice daily for their profession (3 teachers, 1 lawyer, and 1 speech therapist). Another patient is a semi-professional singer. They had been followed on average for 29.8 months at our consultation. Among our group of patients, 9 were diagnosed with an associated autoimmune disease: 3 with SLE; 3 with RA; 1 with Sjögren syndrome; 1 with Hashimoto disease; and 1 with mixed connective tissue disease. One patient had only an elevation of antinuclear antibody without autoimmune diagnosis. In 1 case, bamboo nodes were the first manifestation of the autoimmune disease and helped for the diagnosis of SLE. For the remaining 9 patients, bamboo nodes were discovered after the diagnosis of the autoimmune disease. Except for the autoimmune diseases mentioned in our study, those patients had no other comorbidities. Regarding treatment, 4 patients were treated with speech therapy alone. The mean duration of the speech therapy was 7.5 months with subjective improvement of the voice. Three patients were treated with oral steroids, 1 patient had a treatment of speech therapy and oral steroids combined, 1 patient was treated with oral steroids, and laryngeal steroid injections, and 1 patient had a combination of oral steroids, surgery, and speech therapy (Table 1). Five patients used an antacid treatment. For all patients, there is a subjective improvement of the voice at the end of the treatment. We collected the initial and final GRBAS scale for every patient. When they were not mentioned in the file, we listened to the voice records and established a GRBAS scale. For 7 patients, we have initial and final GRBAS scale results. In 5 patients, there was an improvement in the final grade of the voice from stage G2 to stage G1.

Of the 53 relevant articles retrieved from the literature review, 17 were retained for further analysis. All were retrospective studies and 10 were reports of a single case. All cases concerned women (median age: 37 years). Schwemmle and Ptok [10] described a case of juvenile bamboo nodes in a 13-year-old girl. This was the youngest case described in the literature until now. The presence of bamboo nodes was mostly associated with an autoimmune disease. In most cases, the bamboo nodes were visualized after the diagnosis of the autoimmune disease. The associated autoimmune diseases by order of frequency were SLE, RA, Hashimoto disease, Sjögren syndrome, and progressive systemic sclerosis. In 2 cases, elevation of antinuclear antibody was the only objective manifestation. Oral steroids are the first-line treatment recommended by most authors [1, 11, 12]. Speech therapy is adjuvant treatment in 3 case reports. It is used as first-line treatment combined with basic corticoid therapy in only one article [9]. Table 2 summarizes the details of the literature review.

The results of our study are similar to those found in the literature (Table 3). All the cases described are women with a median age of 37 years both in our group and in the literature. The first and most frequently associated symptom is dysphonia. Among our series of patients, 9 have an autoimmune disease clearly diagnosed with SLE being the most frequently reported, corroborating results described in the literature. In 1 case, we only observe an elevation of antinuclear antibodies without autoimmune diagnosis. Oral steroids are the first-line treatment both for the autoimmune disease and for the laryngeal lesions. As described in the literature, the most frequently used are methotrexate and prednisone. In some cases, oral steroids are completed with laryngeal injections of steroids and surgery. Injected steroids are prednisolone 5 mg (Solu-Decortin®) [7] and triamcinolone (Kenacort®) in our experience. In the literature, only 4 articles (case reports) mention speech therapy as part of the treatment. Our article, on the contrary, suggests that speech therapy is an indispensable complementary treatment. We did not observe a disappearance of the bamboo nodes, but a marked decrease in their size. The quality of the voice is subjectively and objectively better regarding the GRBAS results. Even if our sample of patients is too small to draw statistical conclusions, we conclude that voice quality is better with speech therapy and corticosteroids treatment. Antacid treatment seems to be an additional help when symptoms of gastroesophageal reflux disease are present.

The diagnosis of bamboo nodes is made by laryngoscopy. The most typical aspect is the presence of yellowish transversal lesions protruding most frequently from the middle third surface of the vocal folds (Fig. 1), which is the area the most exposed to vibrations. However, the physiopathology is not fully understood. Ramos et al. [1] reported that bamboo nodes were related to autoimmune diseases and that they could be secondary to local autoimmune reaction. Hosako-Naito et al. [13] considered that mechanical trauma generated by the mucosal wave of the vocal fold could contribute to the formation of bamboo nodes. Li et al. [14] proposed a mixed theory that combined mechanical micro-trauma and a local autoimmune reaction. The reason why the bamboo nodes are reported only in women is not clearly understood, but it is certainly linked to the general high prevalence of vocal fold nodules in women compared to men due to a smaller and thinner vocal fold and higher frequencies oscillation. Although histopathology showed fibrinoid necrosis surrounded by histiocytes in the study by Li et al. [14], it represents a confirmation of the diagnosis and is not essential as the diagnosis is first clinical.

Bamboo nodes are often called “rheumatoid laryngeal nodules” in the literature. We tried to better understand if bamboo nodes and rheumatoid nodules are two different lesions or if these are two names for the same diagnosis. Ylitalo et al. [15] describe 5 patients with vocal fold lesions that they call “rheumatoid nodules,” but the clinical and pathological examination is identical to that of bamboo nodes. The pathophysiology of rheumatoid nodules observed in the larynx can be explained by trauma to small blood vessels at the point of pressure, which cause local pooling of immune complexes [15]. The microscopic aspect and the physiopathological process of bamboo nodes are the same as the classical subcutaneous rheumatoid nodules. Both appear in areas subject to repeated trauma, e.g., in the elbows for rheumatoid nodules and at the midpoint of the vocal folds for bamboo nodes where the contact forces are the greatest during vibration [15]. Woo et al. [16] described 1 patient with RA and 1 patient with SLE having rheumatoid nodules on the vocal folds. The clinical and histopathological description is the same as that of bamboo nodes. Thus, we conclude that laryngeal deposits of autoimmune complexes are named rheumatoid nodules or bamboo nodes without any clinical or pathological difference.

Treatment with systemic steroids can provoke a regression of the bamboo nodes. Murano et al. [8] recommend to start with systemic steroids associated with vocal rest to avoid local micro-trauma. Hosako-Naito et al. [13] suggested surgical treatment by micro-laryngoscopy associated with systemic steroids to avoid recurrence. Bamboo nodes are described as yellow breakable soft tissue that is not encapsulated, which adheres to the vocal muscles within the submucosal space. The lesions spread from the mid-portion of the vocal fold to the anterior and posterior portions. The authors treated 4 patients with surgical excision and observed recurrence in 2 cases. In the first case, a submucosal removal of the lesion was performed. Three months later, the patient presented a recurrence and was treated by betamethasone (0.5 mg/day) with a regression of the lesions after 2 weeks of treatment. In the second case, the recurrence of bamboo nodes was observed 2 months after surgery. Apart from the recurrence, the disadvantage of surgery is that the scar in the vocal folds may worsen dysphonia.

Voulgari et al. [17] suggested a systemic treatment by methotrexate in patients with RA, observing regression of bamboo nodes with standard doses of the treatment. Schwemmle et al. [18] described a local injection of prednisolone 5 mg (Solu-Decortin®) once a week during 4 weeks under local anesthesia directly in the lesion and in the para-lesion area, in addition to the already given methotrexate. After 2 injections, they observed a macroscopic regression of lesions. Following the third injection, the quality of voice worsened and the bamboo nodes remained stable in size. They then performed a surgical excision to the vocal muscle under micro-direct laryngoscopy and observed a deep mucosa and submucosa on the right vocal fold during the procedure, without a clear capsule around the lesion. The authors also described a macroscopically visible loss of substance on the vocal fold. There were no postoperative complications, but dysphonia persisted. Thus, vocal therapy was initiated early after surgery (the optimal delay of time between surgery and vocal therapy is unknown) and, finally, the patient was satisfied with her voice. Schwemmle et al. [18] suggested steroid local injection as first-line treatment, not more than 3 injections with a free interval of 14 days between injections. As the second-line treatment, they advised surgery with careful excision of lesions and speech therapy as adjunct treatment. Bitter et al. [19] also described a case of bamboo nodes treated by surgery in combination with local injection of triamcinolone.

Regarding our personal experience, a local injection of Kenacort® (triamcinolone) under general or local anesthetic seems to also be effective for the regression of bamboo nodes, thus avoiding surgery. Kenacort® is a crystalloid suspension containing acetonide of triamcinolone and combines two effects: anti-inflammatory and immunosuppressive. A dose of 10 mg of Kenacort® is equivalent to 50 mg of prednisone or 200 mg of cortisone, but its half-life has not been clearly determined for intra-lesional injections. We treated a patient with intra-lesional Kenacort® injections (1 mL) that were repeated 3 times with an interval of 5 months each time. The injection was made in the lesion, once under general anesthesia and twice under local anesthesia. The patient was regularly followed up for 2 years. Quality of voice was excellent and we observed a clear regression of the bamboo nodes. She had speech therapy as adjuvant treatment. Speech therapy is recommended in the literature as a complement to surgery or steroid treatments to reduce vocal micro-trauma and to avoid wrong vocal habits. As suggested by Hilgert et al. [9], we postulate functional disorders of the larynx based on vocal abuse in patients with bamboo nodes and underlying autoimmune diseases [9, 20]. Thus, we would recommend speech therapy as first-line treatment combined with systemic steroids.

There are only a few reports of patients described in the literature and this does not allow a gold standard for treatment. Ideally, a prospective study with two groups of patients treated differently (surgery vs. local steroid injections) would be more appropriate to compare the results in an objective manner. Nevertheless, the patients included in our cohort were followed over a long period of time (average follow-up: 29.8 months) and this is probably the longest clinical follow-up in a cohort of 10 patients with bamboo nodes. Taken together, our observations and clinical results suggest that conservative treatment with oral steroids and speech therapy permit good results. We tested local steroid injections on 1 patient with excellent long-term results. Moreover, in our study we note that the bamboo nodes concern women mostly using their voice at work. We can conclude that 3 risk factors for the development of bamboo nodes are female sex, presence of a concomitant autoimmune disease, and use of voice. Given this category of patients, we believe that speech therapy must be a fundamental part of rehabilitation and that it should be practiced for several months. As regards the pathophysiology of bamboo nodes, which are created by vocal fold trauma, speech therapy appears to be the treatment of choice to reverse the process. Our patients were on average followed for 7 months by a speech therapist.

In a more general way, this study teaches us that bamboo nodes may be the first manifestations of an autoimmune disease. The otolaryngologist who observes them must therefore seek an autoimmune disease underlying those lesions. Similarly, the internist who follows a patient with autoimmune disease complaining of dysphonia should refer him to the otolaryngologist in search of bamboo nodes. Management should be multidisciplinary for follow-up and treatment.

Bamboo nodes are rare, but typical lesions of vocal folds, and are usually associated with an autoimmune disease. Until now, bamboo nodes have been reported only in women; most of them were professional speakers like teachers and singers. Bamboo nodes should be looked for in every patient with a diagnosis of autoimmune disease and who complains of dysphonia. All patients with bamboo nodes on vocal folds should be seen by a specialist or undergo an immunologic check-up. Evolution under systemic steroids is frequently favorable, although there is no standard therapy reported in the literature and a gold standard for treatment is still lacking. Our personal experience suggests that conservative treatment seems to be efficient and that speech therapy should be the first-line treatment.

The authors have no conflicts of interest to disclose.

None.