Delayed onset sleep-related stridor due to radiation for thyroid cancer

Abstract

Radiation therapy is the mainstay of treatment for head and neck cancers with both acute and delayed complications. While obstructive sleep apnea is common in the few series of patients undergoing radiation therapy to the neck, the development of sleep-related stridor is exceedingly rare and has typically been reported in the acute treatment setting. We describe a 65-year-old female with 1 year of nocturnal groaning beginning 2 years after radiation therapy for thyroid carcinoma. Polysomnography revealed mild obstructive sleep apnea and sleep-related stridor responsive to nasal continuous positive airway pressure. Our case highlights the importance of screening patients with a history of head and neck radiation for sleep-related breathing complaints at each follow-up visit and consideration of both obstructive sleep apnea and stridor in these patients. Identification of sleep-disordered breathing in these patients may lead to timely treatment and improvement in quality of life.

Citation:

McCarter SJ, Mansukhani MP, Herold DL, Kolla BP. Delayed onset sleep-related stridor due to radiation for thyroid cancer. J Clin Sleep Med. 2022;18(9):2327–2329.

INTRODUCTION

The evolution of obstructive sleep apnea (OSA) in patients with head and neck cancers has been reported to occur commonly following either surgical or radiation therapy but is likely underrecognized.^1,2 However, the development of sleep-related stridor following radiation therapy to the head or neck is very rare, accounting for only 3.7% of cases in one large series of 81 patients with sleep-related stridor.³ We report a case of delayed-onset sleep-related stridor following neck radiation for thyroid carcinoma.

REPORT OF CASE

A 65-year-old female with a past medical history of anaplastic carcinoma of the thyroid presented to the sleep clinic for evaluation of a 1-year history of abnormal groaning at night. Three years prior to presentation she was diagnosed with stage IV anaplastic carcinoma of the thyroid and subsequently adjuvant chemoradiation with 6,600 cGy of radiation in 33 fractions followed by 6 cycles of chemotherapy with docetaxel and doxorubicin. Her initial postradiation course was complicated by dysphagia requiring placement of a feeding tube which was removed 6 months after radiation and fluctuating dysphonia which gradually improved over the following year. Videostrobolaryngoscopy 2 years prior to evaluation in the sleep clinic demonstrated mildly reduced abduction of the left true vocal fold, although she did not have any sleep complaints at that time.

Approximately 1 year before evaluation her husband began noting both snoring and new groaning noises occurring exclusively at night, usually during the second half of the night and the same time each night. He provided a sample of audio that he recorded on his smartphone (see file in the supplemental material ^{(1MB, mp3)} , which is a recording of the patient’s nocturnal “groaning,” raising concern for possible stridor or catathrenia provided by the patient’s spouse at consultation). There were no witnessed apneas, and the patient denied any morning dry mouth or headaches. While the patient’s husband was disturbed by these noises the patient herself was unaware and unbothered by these sounds. She denied daytime sleepiness and had an Epworth Sleepiness Scale of 6. Oncologic evaluation demonstrated no evidence of tumor recurrence or airway obstruction. Esophagogastroduodenoscopy showed mild intrinsic stenosis 15 cm from the incisors which was dilated without changes in her symptoms. She did not undergo laryngoscopy.

Given concern for possible stridor or catathrenia, she subsequently underwent split-night polysomnography, which demonstrated mild obstructive sleep apnea with an apnea-hypopnea index of 5 events/h and respiratory disturbance index of 15.6/h. During all stages but predominantly rapid eye movement supine sleep, loud, high-pitched inspiratory noises were heard, consistent with stridor (Figure 1A). Continuous positive airway pressure at 5 cm of water through a nasal interface eliminated obstructive breathing events and stridor (Figure 1B). She was prescribed continuous positive airway pressure at 5 cm of water, which completely abolished her symptoms and continued to control her stridor at time of follow-up 3 months later with improvement in sleep quality.

Figure 1. Polysomnography demonstrating stridor controlled with continuous positive airway pressure.

Thirty-second epoch of stage N2 sleep demonstrating high-pitched noise recorded by the microphone occurring during the inspiratory phase (black arrows) of the respiratory cycle, consistent with stridor during the diagnostic polysomnogram (A) which was eliminated with continuous positive airway pressure therapy (B).

DISCUSSION

Stridor is a high-pitched and harsh respiratory sound caused by laryngeal dysfunction leading to narrowing of the rima glottidis typically occurring during the inspiratory phase, although it may rarely occur during expiration (usually related to obstruction at or below the glottic level).⁴ Stridor may be confined to sleep or wakefulness or occur during both states. While stridor is typically diagnosable based on presence during the examination, description by witness or audio recording, video polysomnography, or drug-induced sleep endoscopy may be required to differentiate stridor from other conditions, as was the case with our patient.⁵

Sleep-related stridor following radiation to the neck is rare. Of the single individual reported case of radiation-associated nocturnal stridor, the patient presented with airway edema and pharyngitis acutely following radiation rather than in a delayed fashion as seen in our case.² The time from radiation to development of stridor was not clear in the large case series of sleep-related stridor.^2,3 The development of postradiation vocal cord paralysis has been reported as late as 21 years following radiation, which is typically attributed to laryngeal neuropathy, although none of the patients in this series had concurrent stridor.⁶ Mechanisms underlying radiation-induced stridor are likely multifactorial and include laryngeal fibrosis and stenosis, chronic arytenoid and vocal fold edema, and potentially radiation-induced laryngeal neuropathy.^3,6,7

The mechanism for sleep-related stridor in our patient remains hypothetical as laryngoscopy was not performed following the development of her symptoms. Repeat laryngoscopy was deferred as she had no daytime symptoms, continuous positive airway pressure eliminated her stridor, and repeat laryngoscopy would not change her current management as she had a previously known left vocal fold abduction deficit. Although the lack of laryngoscopy does limit our ability to confidently assess the mechanism driving sleep-related stridor in our patient, we hypothesize that it was a combination of factors discussed above given her previously noted left vocal fold abduction deficit, which likely reached a critical threshold during the natural relaxation of airway musculature of sleep resulting in the development of stridor. In fact, in one series, laryngoscopy in 3 patients with laryngeal cancer treated with radiotherapy showed fibrosis and edema of the vocal cords plus abductor dysfunction as the likely etiology of nocturnal stridor.³

The development of sleep-related stridor is important to recognize in patients with a history of radiation to the head and neck as stridor is strongly associated with obstructive sleep apnea, which may worsen patient quality of life and interfere with bedpartner sleep.³ As noted above, the development of sleep-related stridor following radiation is exceedingly rare. However, OSA following radiation to the head or neck is common, with one PSG studying finding 100% of patients with head or neck cancer who had radiation had a respiratory disturbance index of > 15/h and many had symptoms of excessive daytime sleepiness.¹ Importantly, many of the reported cases of OSA following radiation therapy did not have typical risk factors for OSA such as obesity, suggesting intrinsic airway changes resulting from radiation therapy lead to upper airway obstruction in these individuals.¹ Additionally, in some cases stridor may be associated with a higher risk of sudden nocturnal death, particularly in those with multiple-system atrophy, highlighting the importance of differentiating stridor from snoring or catathrenia, which do not carry the same risk of sudden death.⁸ Nocturnal continuous positive airway pressure effectively controlled both OSA and stridor in our patient and is typically effective in controlling sleep-related stridor in most cases.³ Our case highlights the importance of screening for symptoms of sleep-disordered breathing in patients with a history of head and neck radiation, even years after their initial treatment as the onset of symptoms may be delayed by years.

DISCLOSURE STATEMENT

All authors have reviewed the manuscript and agreed with the content. The authors report no conflicts of interest.

ABBREVIATION

OSA

obstructive sleep apnea