Introduction
Painful swallowing or pain on swallowing is known as odynophagia [1]. The pain can be caused by damage to the mucosa or the presence of lesions in the swallowing pathway, pharyngitis, regurgitation, candida infection of the esophagus, inflammation of the esophagus following the consumption of certain substances such as acid or alkaline, radiotherapy, the use of certain medicines (such as antibiotics and cardiac pills, often occur in the elders), damage to the swallowing pathway because of swallowing some solids (such as fish bones), esophagitis (especially in acquired immunodeficiency syndromes) [2], and acute epiglottitis [3, 4]. Shaker and Koch (2007) explained the swallowing disorder (dysphagia) and painful swallowing. They wrote, “People with pain on swallowing may indicate swallowing disorder, while patients with swallowing disorder will not have pain on swallowing” [1]. However, certain studies do not support this statement. The co-occurrence of swallowing disorder and pain on swallowing has been reported in rheumatism and chronic inflammatory changes such as Crohn disease [5، 6].
Contrary to Shaker and Koch’s opinion, Triggs and Pandolfino (2019) described swallowing disorder as the feeling of food stuck in the esophagus or chest and believed that if this feeling was accompanied by pain, it would be pain on swallowing or food sticking as it was associated with sticking or regurgitation [8]. There seems to be a heterogeneity in the terminology or co-occurrence of these two disorders. If studies show that these disorders are separate, the assessment and treatment protocols will be different; otherwise, managing the pain on swallowing is one of the priorities. 
In literature, pain is considered a complex and multidimensional perception that can be examined from different perspectives. For example, several dimensions have been mentioned for pain in patients with chronic pancreatitis, including severity, pattern, factors provoking pain, spreading pain, and qualitative pain descriptors [16، 17]. Since pain on swallowing is related to the digestive system, there should be similarities between its characteristics and pain characteristics reported for internal organs related to digestion. The lack of clarity in the literature regarding the existence of pain on swallowing and its importance for speech therapists (STs), any possible relationship between pain on swallowing and swallowing disorders, and the feasible dimensions of pain on swallowing have motivated us to run a qualitative study to shed light on these issues. 
This study tried to investigate the presence of pain on swallowing in patients with swallowing disorders, the dimensions of pain on swallowing, its effects on the patient’s quality of life, and the strategies for managing this problem by patients and STs. 

Materials and Methods
The sampling method was purposive. We interviewed STs who had clients with swallowing disorders in the last three months, had at least four years of clinical work experience in speech therapy, had a bachelor’s degree or higher in speech therapy, and signed the consent form. Lack of familiarity with swallowing disorder was the only exclusion criterion. To identify experts, by review of the related literature, the correspondence authors were contacted by phone or e-mail. If they met the inclusion criteria, the study information sheet and consent form were sent off. Then, using the snowball technique, they were asked to introduce someone in this field to the researcher [18]. 
At the end of the interview with each specialist, we asked to introduce a patient who met the inclusion criteria of this study. Then, the specialist provided the patient with the research information sheet and the consent form. If the patient wanted to participate in the study, the time and place of the interview were determined by their specialist. We interviewed patients suffering from chronic swallowing disorders (i.e. swallowing disorder that has lasted more than two weeks) [19] for any reason (the presence or absence of swallowing disorder was determined by the patient’s score in the Mann assessment of swallowing ability (MASA) test), ability to follow verbal commands, and aged between 18 and 85 years. The type of swallowing disorder was not considered in this study so that every patient with a swallowing disorder could be interviewed and get more information about pain on swallowing. If the patient’s level of consciousness decreased during the interview or the patient did not want to participate in the study, the patient was removed from the list of participants. 
Of 15 experts who signed the consent form, only 11 met the inclusion criteria to be interviewed. Also, 38 patients received the consent form and invitation letter, but only 15 agreed to participate in the study. 

Study procedure
Interviews were conducted from July to November 2022. Initial information was obtained with STs through a phone call. Experts could participate in this study online (on WhatsApp) or in person (at the expert’s workplace). Interviews with patients were conducted face-to-face in Semnan, Tehran, and Babol cities, Iran. The researcher continued interviewing the participants until the last two to three interviews, which yielded no new information. To conduct semi-structured interviews, some general and open questions were asked for both groups.

Data analysis
Data analysis was done using the method proposed by Granheim and Lundman in four stages: Transcription immediately after the interview, detailed study of the transcriptions and extraction of meaningful units, the definition of subcategories, and finally, the introduction of main themes.

Results
The average time to interview the patients was about 30 minutes, and the average time to interview the experts was 20 minutes. Six main themes were obtained in the interviews with experts, including the pattern and pain duration, the most common place and time of pain, the most common cause/provoking factor of pain, and the most common type of pain. Pain intensity was added to the previous themes in the patient interview.

Temporal pattern
The frequency of pain the patients experience during swallowing disorders differs during the day. Some described this pain as constant and some intermittent. 
One of the specialists (ZA) answered that the patients reported a specific pattern of pain: “Yes, usually they have a fixed pattern; I have seen someone with pain, it was constant, that is, it did not have a specific time, it was continuous.”
One of the patients (MSH) in response to “Can you tell me about the pain pattern?” Answered: “I always have this pain; when I eat, it gets worse.”

Pain severity 
All the experts reported that they did not examine the pain severity either qualitatively or quantitatively. However, when the patients were asked to rate their pain on a quantitative scale from 0 to 10, they reported different numbers for the least, average, and most pain severity they had experienced. Consider the following two examples:
MSH patient said, “There was a lot of pain in the larynx area; it was 3 to 5, but it increased to 7.”
One of the experts (FKH) in response to the question regarding pain severity, pointed out, “Those who report pain in the throat and larynx usually have a very mild pain; it gets worse when they eat, only when they swallow.”

Location of pain
Examining the location of pain in patients was one of the issues that experts and patients in this study were asked. This question referred to both the swallowing pathway and other body parts. Regarding recurrent pain or pain in other parts of the body at the same time as pain on swallowing, most clients reported pain in the larynx and esophagus. However, only four experts mentioned recurrent ear and neck pain along with the pain on swallowing. For the location of pain on swallowing, in both groups of participants, responses referred to common points along the swallowing pathway. 
Expert JB said, “Most of the pains are felt in the pharynx, the end of the pharynx, I mean the bottom of the pharynx, that is, they feel the pain in the larynx. I did not see the pain in the upper parts; the truth is, it is mostly located in the laryngopharynx.”
Patient PO mentioned, “End of the tongue”, and patient MAZ said, “More in the throat to upper parts, from the larynx to upper parts.”

Time of pain
All the patients who reported pain in this study agreed on the time of pain and often limited themselves to saying one phrase: “While swallowing.”
Specialists answered a bit elaborately in this regard. Specialist FKH said, “... it gets worse when they eat, only when they swallow, those with esophageal pain....” Finally, they also referred to a similar time, “Swallowing time.”

Stimulating/provoking factors
Based on the patients’ answers, the food texture seemed to be the most important provoking factor, especially when it was chewy or hard. According to experts, the texture of the food was also important, but in a different way.
KSH specialist said, “Eating and especially solid food.”
Another specialist (JB) answered, “It’s different. For example, some people say that I feel pain when I swallow my saliva. ... Some people say that it is painful when I swallow liquids, and others say that I feel pain when I eat solid food.”

Type of pain
Among the other aspects of pain mentioned in the literature was the type of pain described by the patients. That is, what term did they use when describing the pain? Patients and experts in this study used different words to describe pain on swallowing. For example, patients described their type of pain with the following words.
MA said, “Shooting pain with a feeling of choking.”
AS mentioned, “Vague with choking.”
MAZ answered, “Feeling of choking and pressure.”
The group of experts reported a list of different words. For example, MD said, “Usually they report a shooting pain in their throat area, and it’s penetrating.” ZA mentioned, “What I get [is] they feel like they’re choking, something is choking the throat like a lump [they say] more of a feeling of choking.” 
JB said, “It’s a pins-needles pain. I feel a stone in my throat; I feel pressure. It’s like they’re stabbing a knife down my throat. They have a vague pain all the way, and when they swallow, the pins-needles pain becomes intense.”

Pain duration
The literature considers the pain duration as one of the important characteristics of pain. Therefore, in this study, patients and experts were asked about the persistence of pain. While the group of experts considered the etiology of swallowing disorder to respond, patients hit the point when they answered this question.
MD specialist said, “In psycho cases, pain exists before, during, and after swallowing. However, in clients with known etiology, pain duration is shorter with some foods, and these people change their diet to experience less pain, and 7 to 8 minutes after eating, the pain stops. It will end.”
Patient AS said, “It lasts two or three seconds after the first two bites, and then it’s gone. Only the first two or three bites are painful, and the rest is pressure and stress from choking.” Patient MAZ and MSH responded similarly: “No, only when swallowing.”

The effect of pain on the quality of life
The patients who confirmed the presence of pain continued to explain the negative effects of this pain and swallowing disorder on their lifestyle, such as, “Awful, first of all, when I go out, I try not to eat anything hard at all. I want to eat many things, but because it might stick in my throat, or if I have those coughs, I won’t eat”, said AS. Experts’ responses were aligned towards the impact of swallowing disorder and not specifically pain on swallowing on lifestyle. 
MD said, “They all admit that it has affected the quality of their lives. They all say that we don’t enjoy living. They all say with sorrow that one of the joys of life is eating, and we can’t enjoy it. It’s really like an envy for them. Their lifestyle has changed. For example, their diet, the way they eat, has changed.”

Therapeutic actions
Regarding the actions taken by the patients to relieve the pain, PO answered, “Swallowing therapy.” AS and MA mentioned, “Visiting various specialists and swallowing therapy.” MAZ said, “They elevate the head of my bed so that I can sit up”, and MSH mentioned, “I bring my head up.” Specialists offered similar treatment approaches, including changing the position, referring to a specialist, and finally changing the food texture.

Discussion
The present study was conducted to investigate the existence of pain on swallowing, its characteristics, the possible impact of this pain on patients’ quality of life, and its treatment strategies. After interviewing experts and patients, it was found that there is pain on swallowing. However, it has not been evaluated and treated as one of the serious symptoms of swallowing disorder or as a separate disorder. Seven main themes were found in this study for pain on swallowing: Temporal pattern, severity, location, time, duration, provoking factors, and type of pain. It was found that the pain, along with swallowing disorder, had a negative impact on the patient’s lifestyle. Some patients have resorted to compensatory treatments to solve this problem; others have referred to STs. Some experts have recommended an interdisciplinary approach to treatment, and some have directly benefited from the methods of treating swallowing disorders to reduce or eliminate pain on swallowing.
While all experts in the field of swallowing disorders pointed to pain on swallowing, this consensus was not seen in patients with swallowing disorders. So, only 40% of patients with swallowing disorders confirmed pain on swallowing. Non-validation of pain by others does not necessarily mean it does not exist. Perhaps other problems in these patients have masked the pain because pain is defined as: “An unpleasant sensory and emotional experience accompanied by actual or potential tissue damage, or described by such damage” [26].
Using the literature and especially the study of Kuhlmann et al. [16] we asked open-ended questions in this study to explore different dimensions of pain. This study confirmed all the dimensions of pain related to the digestive system [16، 27]. The remarkable finding in this study was that the experts did not consider pain severity. According to the experts’ recommendations, this characteristic is one of the sensory and physiological dimensions of pain and should be considered for acute pain [28]. There are several scales to evaluate this pain parameter, and it is necessary to view this characteristic in assessing pain on swallowing [29-32].
The temporal pain pattern in this study was not consistent and predictable for all patients. Depending on the etiology of swallowing disorder, experts and patients reported pain “always”, “sometimes”, or “not at all”. Studies on the digestive system and its pains have reported the same time pattern variation [16، 17، 33]. Since swallowing occurs at the beginning of the digestive tract, the similarity of the temporal pattern of pain on swallowing with pain reported in other parts of the digestive system is understandable.
There was a consensus between patients and experts about the location of pain. Most of the focus was on the pharynx and larynx. The pain started when swallowing, as reported by all patients and experts. Matching the location of pain and its onset time can be a starting point for providing therapeutic and compensatory solutions to avoid experiencing pain in these patients. In the review of the literature related to swallowing disorder, the prevalence of oropharyngeal swallowing disorder has been reported to be much higher than other types of swallowing disorder: 14%-35% in older adults [34], 51% in institutionalized elderly [35], and in 10% of patients after stroke [19]. This issue has caused many to use the term “swallowing disorder” when referring patients with oropharyngeal swallowing disorder [36]. This issue, together with the similarity in the description of pain on swallowing in this study (choking feeling) and symptoms of oropharyngeal swallowing disorder (sticking of swallowed material to the throat, coughing or choking, wet or gurgling sound, regurgitation of food in the mouth and decreased weight [36، 37] can lead the researcher and the reader to point a probable overlap in the occurrence of oropharyngeal swallowing disorder and pain on swallowing. Perhaps this condition has made the experts in this field and even the patients oblivious to the pain of swallowing; the conclusion in this section needs more extensive studies.
Another issue that strengthens the co-occurrence of oropharyngeal swallowing disorder and pain on swallowing is the provoking factors of pain on swallowing. The texture of the food, especially when it is solid, could trigger pain in people. Interestingly, one solution for the oropharyngeal swallowing disorder is to change the food texture or body position as some compensatory technique [38]. Even in managing oropharyngeal swallowing disorder, experts use two compensatory approaches and rehabilitation exercises [36]. The participants in this study also used the same methods to manage pain on swallowing. It seems that the swallowing disorder rehabilitation team should be more careful in differentiating pain on swallowing and oropharyngeal swallowing disorder. Research has shown that compensatory strategies for managing swallowing disorders do not have long-term effects; on the other hand, it has been advised to reach long-term effects, rehabilitation exercises such as Mendelsohn maneuver [39], Shaker’s exercises [37، 40], or tongue strength exercises [41]. Again, the literature has documented few positive effects of these exercises [36]. Perhaps the co-occurrence of swallowing disorder and pain might be the reason that these techniques did not reach their optimal level of remediation. More studies in this field can be helpful.
Pain was present before, during, and after swallowing in patients whose swallowing disorder lacks an organic basis. Perhaps providing services according to the 7-factor model of Davidson et al. [15] with a particular focus on aspects of emotional distress, support, positive coping strategies, negative coping strategies, and activity can better manage pain on swallowing in these patients. In the patients whose swallowing disorder had an organic basis, the pain depended only on the swallowing time. In this group, separation or investigation of co-occurrence of oral-pharyngeal swallowing disorder and swallowing pain is a prerequisite for providing therapeutic services. It seems that with these conditions, the treatment of swallowing and pain on swallowing should follow a different plan depending on the classification of swallowing disorder (organic versus psychogenic); future studies can provide more clarity in this section.
The existing literature has documented the negative impact of swallowing disorders on the quality of life of affected people [42، 43]. This study also showed that swallowing disorder is not the only cause of reduced quality of life in affected people. Still, pain on swallowing, if present, can simultaneously affect the quality of life of these people. More studies are needed to separate the adverse effects of pain on swallowing and swallowing disorders on the quality of life of affected patients.

Conclusion
This study showed that pain on swallowing is one of the characteristics of swallowing disorder in affected patients, and experts in this field must pay attention to it in clinical considerations. Future studies in this field can focus on different dimensions of pain in these patients and produce proper scales.

Study limitations
This study adopted a qualitative approach to investigate pain on swallowing, so the interview was terminated when the participants’ answers did not provide new information regarding the study questions. However, transcribing these interviews and extracting themes and subcategories led to new windows for research and clinical discussion. Quality of life and pain management were not the main dimensions of characteristics regarding pain on swallowing. Therefore, the researchers of this study did not focus on it; reaching any definitive results in these two areas requires more extensive studies. It is hoped that future studies can provide valuable clues regarding pain on swallowing, its prevalence, and strategies for managing or treating this disorder.

Ethical Considerations

Compliance with ethical guidelines
This study was approved by the Ethics Committee of Semnan University of Medical Sciences (Code: IR.SEMUMS.REC.1400.235). Written consent was obtained from all participants.

Funding
The paper was extracted from the master's thesis of Fatemeh Kiaee Darounkola, approved by Department of Speech Therapy, School of Rehabilitation, Semnan University of Medical Sciences.

Authors' contributions
Conceptualization: All authors; Research, review and analysis: Fatemeh Kiaee Darounkola and Masoomeh Salmani; Methodology: Seyed Abolfazl Tahidast; Drafting: Jalal Bakhtiyari; Writting: Fatemeh Kiaee Darounkola, Masoomeh Salmani and Seyed Abolfazl Tahidast; Editing: All authors; Review: Kiaee Darounkola and Masoumeh Salmani; Final approval: Jalal Bakhtiyari.

Conflict of interest
The authors declared no conflict of interest.

Acknowledgments
The authors are grateful to Semnan University of Medical Sciences for the spiritual support of this research.

 

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