As you can probably tell, I truly enjoy sharing ideas with colleagues and patients about some of the challenges we face in treating snoring and obstructive sleep apnea. One topic that provokes particularly intense discussion is the role of the epiglottis in sleep apnea. My colleague, Dr. Andrew Goldberg, came up with the title for a lecture I have given (and which I have used for this blog post), based on the notion that the epiglottis protects us from hazards but also can be a primary cause of obstructive sleep apnea. The epiglottis (see illustration) is a piece of cartilage, covered with mucosa (lining of the throat), that sits in the lower part of the throat, where its major role is to assist in swallowing. During swallowing, the muscles of the throat push the epiglottis backwards (in addition to other throat movements) to cover the voice box (larynx) during swallowing and prevent food and liquid from entering the lungs.
Based on our research utilizing drug-induced sleep endoscopy and the work of others, it is estimated that about 10% of patients with sleep apnea appear to have their epiglottis substantially either fall backwards or fold in half during sleep. Both of these can narrow the space for breathing and contribute to sleep apnea. For patients with sleep apnea and the physicians who treat them, there are two questions:
- What is the best way to determine if the epiglottis is playing a role?
- How do we treat the epiglottis?
Identifying the epiglottis as an important factor in sleep apnea
There are many evaluation techniques for patients with snoring and obstructive sleep apnea. I have completed a number of studies related to drug-induced sleep endoscopy because I think it offers unique insight into what is causing blockage of breathing during sleep. When done carefully, this evaluation may reproduce a sleep-like state that allows us to examine what structures in the throat may be contributing to sleep apnea. This is very different from most other techniques, which are performed with patients awake. Identifying the role of the epiglottis may be a very important role for sleep endoscopy, as other evaluation techniques are unable to determine this.
Because drug-induced sleep endoscopy has some risks and costs, many of us who have tried to determine other ways to obtain the information we get from sleep endoscopy without the risks and costs. I have noticed two things in patients where the epiglottis plays an important role. One is that these patients may get a sensation of choking with their continuous positive airway pressure (CPAP) therapy, which is not only dramatic and disturbing but which is very different from other reasons for being unable to tolerate CPAP. This may occur because CPAP could, at least theoretically, be pushing the epiglottis backwards to create a complete seal in the throat that cannot be relieved by higher CPAP pressures. This is very different from blockage due to other structures like the soft palate or tongue, where blockage is relieved when the CPAP pressure rises. The other findings common to many patients with an epiglottis role come from the fiberoptic telescope that I use to examine patients in the office. The epiglottis can often be sitting further back, almost positioned against the back of the throat, and often there is a curve to the upper half of the epiglottis, almost as if it is bent forward (towards the tongue) over time, as the epiglottis is repeatedly falling back against the back of the throat. Relying on these findings have not replaced drug-induced sleep endoscopy in my practice, but they can make me suspicious about a role for the epiglottis.
How to treat the epiglottis in sleep apnea surgery
Once we suspect a role for the epiglottis, whether from drug-induced sleep endoscopy or some other evaluation, what should we do? As described above, increasing CPAP pressures may only make the problem worse. Decreasing CPAP pressures also will not work, as there often needs to be enough pressure to open the breathing passages. So we must look at alternatives, either to address the sleep apnea by themself or in combination with treatments like CPAP. Behavioral changes like weight loss, avoiding sleep on one’s back, and eliminating alcohol intake within 3 hours of bedtime will likely help many patients, but they are not specifically targeted to the epiglottis. Oral appliances move the lower jaw forward and can also be very beneficial, but they also do not address the epiglottis directly. Although surgery is not the only option for these patients, it is the only category of treatment that can focus on the epiglottis.
The two major types of procedures that are directed more specifically at the epiglottis are removal of a portion of it (partial epiglottectomy) and hyoid suspension. European colleagues have substantial experience with partial epiglottectomy, but the two major published studies (brief summaries here and here) of the procedure come from a collaboration between surgeons in New Jersey and Israel. They selected patients with one of the findings mentioned above (positioning of the epiglottis towards the back of the throat during awake physical examination in the office) and performed a somewhat-aggressive removal of part of the epiglottis. Their approach produced dramatic improvements, clearing up sleep apnea in almost 80% (21/27) of those in one study. In Europe, this is a common approach for patients who have an epiglottis contributing to sleep apnea; although my colleagues tell me their results are very good, there are no other studies reporting on results with this procedure alone. Personally, I have been concerned about being so aggressive because of the risks of having food or liquid fall into the lungs when attempting to swallowing, but my results have not been as impressive as theirs.
The hyoid suspension procedure treats the epiglottis differently. The hyoid bone is a relatively thin, horseshoe-shaped bone in the neck. The hyoid bone in humans is unique in that it can move. A mobile hyoid bone appears to have been one of the evolutionary changes important in the development of speech, but it likely also contributes to our risks for developing sleep apnea (which is not seen in most animals, except for some dogs). The hyoid bone is important in sleep apnea because it has attachments to a number of other structures, including the epiglottis (through the hyoepiglottic ligament) and muscles that are next to or surround the throat (including the middle pharyngeal constrictor). During sleep, muscles relax, and the hyoid bone is free to move towards the back of the throat, allowing the structures attached to it to fall into the throat and block breathing. The hyoid suspension procedure involves pulling the hyoid bone forward and using stitches to secure the hyoid bone either to the top part of the Adam’s apple (thyroid cartilage) in a slightly-downward direction or to the lower part of the lower jaw (mandible). These hyoid suspension techniques have not been compared side by side, but we completed a study in a small number of human cadavers that compared pulling the hyoid bone forward in different directions. This study suggested that the best direction may be directly forward, closer to the suspension to the thyroid cartilage. This is the hyoid suspension technique that I use in my own practice.
What do I do if I am worried about the epiglottis?
I believe strongly that the epiglottis plays an important role for about 10% of patients with obstructive sleep apnea. There are clues from the medical history and physical examination that make me more or less concerned about this, but the main way I check for the role of the epiglottis is with drug-induced sleep endoscopy. I have had success treating these patients using both partial epiglottis removal and hyoid suspension. In speaking with my patients, we combine specific findings from their examination as well as their preferences (these procedures have slightly different risks and characteristics) to develop a joint decision about the best option for them.