Prevalence of profound laryngeal sensory neuropathy in head and neck cancer survivors with feeding tube-dependent oropharyngeal dysphagia
Mehdizadeh, O. B., Dhar, S. I., Evangelista, L., Nativ‐Zeltzer, N., Bewley, A. F., & Belafsky, P. C. (2019). PubMed.
Terms within article:
Summary of Article:
Swallowing is such a common everyday action that it goes unnoticed as a very complex process that involves the precise coordination of many sensory and motor functions at once. In fact, a single swallow involves 6 of the 12 cranial nerves in the human body and more than 50 individual or paired muscles for every swallow. Swallowing disorders (dysphagia) is a well-documented side effect of radiation/chemo-radiation treatment for head and neck cancer (HNC) that can, in some cases, lead to long-term feeding tube dependence. HNC survivors commonly report that long-term feeding tubes are seen as one of the most significant obstacles to increased quality of life after radiation/chemo-radiation treatment.
This retrospective review investigated the occurrence of profound Laryngopharyngeal Sensory Neuropathy (LSN) in 43 HNC survivors who were feeding tube dependent longer than six months after radiation/chemo-radiation. LSN is defined as damage to nerves that innervate the swallowing-tract and cause dysphagia. LSN is thought to be the result of direct or indirect damage to the Recurrent Laryngeal Nerve (RLN), a branch of the tenth cranial nerve, Vagus (X). The RLN’s most important job is to protect the airway by controlling the muscles that open and close the vocal folds and sensing if materials have passed below the vocal folds and into the airway. The RLN also supplies sensory information to another part of the Vagus (X) nerve responsible for the cough reflex that ejects materials that enter the airway. When swallowing, sensation or sensory information is what drives motor/muscle actions. Without proper sensation in the swallowing-tract, proper muscle function cannot be easily initiated, leading to aspiration and feeding tube dependence.
Researchers evaluated and tested all 43-feeding tube dependent subjects and determined that 79%, 34 of the 43, had profound LSN. The most common swallowing deficits of those with profound LSN included: pharyngeal weakness, weakened hyolaryngeal elevation (hyoid bone and cartilage elevation needed to open UES), reduced Upper Esophageal Sphincter (UES) opening, and reduced sensation in the swallow-tract that can cause a delayed/absent swallow trigger and reduced airway protection thus leading to material entering the airway causing aspiration and potentially pneumonia. Of those 43 total subjects, 100% of those with LSN and 56% of those without LSN reported recurrent pneumonia. Interestingly, researchers did not find significant differences between those with LSN and those without LSN in pharyngeal weakness, hyolaryngeal elevation, UES opening, and penetration/aspiration of material. Researchers believe that this finding could be due to two factors. One, all subjects in this study were already feeding tube dependent due to severe dysphagia at the start of the study, and two, the study was small and lacked control groups. Therefore, a more well-designed study with control groups should be conducted to obtain conclusive results.
What researches can conclude from this study are the following:
1. LSN, in combination with tongue and or throat fibrosis, stenosis, and cranial nerve motor deficits, can lead to profound swallowing malfunctions.
2. HNC survivors with LSN have higher rates of recurrent pneumonia compared to survivors without LSN.
3. Survivors who are feeding tube dependent with LSN can aspirate their secretions (saliva/spit), causing silent aspiration due to reduced sensation in the swallowing-tract.
4. Development of LSN may occur slowly over time after radiation/chemo-radiation treatment. Current research shows that the average time of onset is from 3.4 years – 14.6 years post-treatment, though more research is needed to confirm results.
Overall, the prevalence of profound LSN is high in HNC survivors who are feeding-tube dependent beyond six months after radiation/chemo-radiation treatment. Recurrent pneumonia is also high in those with and without LSN who are feeding-tube dependent beyond six months post-treatment. This study's findings suggest that LSN is not the sole cause of feeding-tube dependence and recurrent pneumonia beyond six months post-treatment but a combination of LSN, fibrosis, cranial nerve motor deficits, and stenosis compound over time to cause dysphagia.
Possible Questions to ask your healthcare team:
Reference: Mehdizadeh, O. B., Dhar, S. I., Evangelista, L., Nativ‐Zeltzer, N., Bewley, A. F., & Belafsky, P. C. (2019). Prevalence of profound laryngeal sensory neuropathy in head and neck cancer survivors with feeding tube‐dependent oropharyngeal dysphagia. Head & Neck. doi:10.1002/hed.26059
Summary written by Sonya Collins; Edited by Wendy Liang
January 8th, 2020
Terms within article:
- Laryngopharyngeal sensory neuropathy (LSN): damage to nerves within the swallowing-tract (specifically the larynx and pharynx)
- Radiation-induced fibrosis: damaging side effect of radiation treatment; the excessive formation of fibrous (thickened) tissue during a reactive or healing process
- Pharyngoesophageal stenosis (stricture): narrowing of the pharynx and or upper esophagus; one of the most frequent post-treatment morbidities in head and neck cancer patients
- Retrospective cohort study: participants already have a known ailment or outcome; researchers study the past and conduct present-day testing to determine why something has occurred
- Upper Esophageal Sphincter (UES): entrance to the esophagus; UES is closed during breathing to prevent air in the stomach and open during swallowing to permit materials into the stomach
- Aspiration: material enters airway BELOW vocal folds
- Penetration: material enters airway ABOVE vocal folds
- Cranial nerves: 12 pairs of nerves that arise directly from the brain; nerve pairs can be sensory, motor, or mixed (both sensory and motor); sensory nerves help us see, taste, hear, feel, smell; motor nerves help us move our muscles
- Vagus Nerve (X): one of the 12 cranial nerves in the human body; it has two branches, the Recurrent Laryngeal Nerve (RLN) and the Superior Laryngeal Nerve (SLN).
Summary of Article:
Swallowing is such a common everyday action that it goes unnoticed as a very complex process that involves the precise coordination of many sensory and motor functions at once. In fact, a single swallow involves 6 of the 12 cranial nerves in the human body and more than 50 individual or paired muscles for every swallow. Swallowing disorders (dysphagia) is a well-documented side effect of radiation/chemo-radiation treatment for head and neck cancer (HNC) that can, in some cases, lead to long-term feeding tube dependence. HNC survivors commonly report that long-term feeding tubes are seen as one of the most significant obstacles to increased quality of life after radiation/chemo-radiation treatment.
This retrospective review investigated the occurrence of profound Laryngopharyngeal Sensory Neuropathy (LSN) in 43 HNC survivors who were feeding tube dependent longer than six months after radiation/chemo-radiation. LSN is defined as damage to nerves that innervate the swallowing-tract and cause dysphagia. LSN is thought to be the result of direct or indirect damage to the Recurrent Laryngeal Nerve (RLN), a branch of the tenth cranial nerve, Vagus (X). The RLN’s most important job is to protect the airway by controlling the muscles that open and close the vocal folds and sensing if materials have passed below the vocal folds and into the airway. The RLN also supplies sensory information to another part of the Vagus (X) nerve responsible for the cough reflex that ejects materials that enter the airway. When swallowing, sensation or sensory information is what drives motor/muscle actions. Without proper sensation in the swallowing-tract, proper muscle function cannot be easily initiated, leading to aspiration and feeding tube dependence.
Researchers evaluated and tested all 43-feeding tube dependent subjects and determined that 79%, 34 of the 43, had profound LSN. The most common swallowing deficits of those with profound LSN included: pharyngeal weakness, weakened hyolaryngeal elevation (hyoid bone and cartilage elevation needed to open UES), reduced Upper Esophageal Sphincter (UES) opening, and reduced sensation in the swallow-tract that can cause a delayed/absent swallow trigger and reduced airway protection thus leading to material entering the airway causing aspiration and potentially pneumonia. Of those 43 total subjects, 100% of those with LSN and 56% of those without LSN reported recurrent pneumonia. Interestingly, researchers did not find significant differences between those with LSN and those without LSN in pharyngeal weakness, hyolaryngeal elevation, UES opening, and penetration/aspiration of material. Researchers believe that this finding could be due to two factors. One, all subjects in this study were already feeding tube dependent due to severe dysphagia at the start of the study, and two, the study was small and lacked control groups. Therefore, a more well-designed study with control groups should be conducted to obtain conclusive results.
What researches can conclude from this study are the following:
1. LSN, in combination with tongue and or throat fibrosis, stenosis, and cranial nerve motor deficits, can lead to profound swallowing malfunctions.
2. HNC survivors with LSN have higher rates of recurrent pneumonia compared to survivors without LSN.
3. Survivors who are feeding tube dependent with LSN can aspirate their secretions (saliva/spit), causing silent aspiration due to reduced sensation in the swallowing-tract.
4. Development of LSN may occur slowly over time after radiation/chemo-radiation treatment. Current research shows that the average time of onset is from 3.4 years – 14.6 years post-treatment, though more research is needed to confirm results.
Overall, the prevalence of profound LSN is high in HNC survivors who are feeding-tube dependent beyond six months after radiation/chemo-radiation treatment. Recurrent pneumonia is also high in those with and without LSN who are feeding-tube dependent beyond six months post-treatment. This study's findings suggest that LSN is not the sole cause of feeding-tube dependence and recurrent pneumonia beyond six months post-treatment but a combination of LSN, fibrosis, cranial nerve motor deficits, and stenosis compound over time to cause dysphagia.
Possible Questions to ask your healthcare team:
- Am I at risk of developing LSN?
- Is there specific testing available to diagnose LSN?
- Are there any treatments for LSN? What does recovery look like?
- Will insurance cover therapy needed for LSN?
- Will I be able to have my feeding tube removed if I can recover from LSN?
- What will my new normal look like after therapy for LSN?
Reference: Mehdizadeh, O. B., Dhar, S. I., Evangelista, L., Nativ‐Zeltzer, N., Bewley, A. F., & Belafsky, P. C. (2019). Prevalence of profound laryngeal sensory neuropathy in head and neck cancer survivors with feeding tube‐dependent oropharyngeal dysphagia. Head & Neck. doi:10.1002/hed.26059
Summary written by Sonya Collins; Edited by Wendy Liang
January 8th, 2020