4.1. Main Findings:
In this study, based on published tweets, we found that X users were most interested in discussing paraplegia. Through LDA, we found that treatment was the most prevalent topic, followed by etiology and research advancements. Notably, in the case of fibromyalgia, symptoms and the definition of the disease have garnered much attention. The dominant emotions were "fear" and "sadness". Surprisingly, there was no correlation between the number of tweets and their impact measured through generated retweets; ultimately, when analysing the temporal evolution, the trend in the number of tweets was homogeneous, with a particular peak observed in fibromyalgia-related tweets.
The interest generated by different chronic pain-related diseases among X users was homogeneous, except in the case of neuropathy, where the number of tweets was clearly lower. We know that neuropathy affects older populations more than younger populations, and generally, X users tend to be younger, limiting the information published regarding this condition. On the other hand, the diagnosis of neuropathic pain is underestimated, and these negative or stigmatizing attitudes have led to less interest from society19. However, we found studies where such stigmatization further increased the demand for validated information from sources other than formal institutions, more frequently from social media platforms20,21. Conversely, the popularity of paraplegia among X users could have a direct relationship with various clinical and preclinical studies from recent decades reporting on the potential effects of epidural electrical stimulation in the treatment of spinal cord injuries (SCIs)22, as well as the search for other alternative treatment strategies23.
Social media plays a significant role in shaping opinions and emotions through the dissemination of information24, and we believe that retweets serve as a measure of users' particular interest in a topic, which is associated with the emotions evoked by tweets25. For instance, sentiment analysis of a large number of messages can provide valuable insights into the mood of the crowd12 and their health status26. The predominance of emotions related to "sadness" and "fear" may be justified because chronic pain is one of the most common health problems in the population, and leads to functional disability, individual suffering, and high costs27. These negative emotions also stem from a lack of adequate treatment, as studies in Europe report that approximately 14% of patients discontinued treatment owing to side effects, and up to 40% received treatment they deemed inadequate19.
In this way, diseases associated with chronic pain are a cause for concern among X users, as reflected in their posts, especially regarding headache, considered the most common neurological disorder in the population28, and fibromyalgia, both of which have a negative impact on people's well-being29. Furthermore, the subjectivity in the diagnosis of both conditions undermines the perception that the population has of these diseases. Like in individuals with mental illnesses, addiction, and many other painful disorders, migraine is invisible and cannot be measured or confirmed by an objective diagnostic test. Compared to individuals with epilepsy, which has a physical manifestation, individuals with chronic migraine are seen as less reliable, less inclined to exert themselves, and more prone to feigning illness30,31. Thus, "less visible" diseases or those causing greater societal rejection are the most feared and can lead to greater sadness, despite being less severe than conditions such as paraplegia or multiple sclerosis.
On the other hand, the number of tweets addressing emotions such as "joy" and "surprise" regarding conditions such as paraplegia, multiple sclerosis, and headache is surprising. This relationship could be explained by recent studies indicating that the European population with SCIs32 shows high or very high satisfaction with the availability of medical care related to these injuries. In multiple sclerosis, the exact etiology is still unclear, but there has been an association with an abnormal response within the central nervous system, possibly due to an infectious agent33. As knowledge about Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to advance, the literature has shown that a significant number of patients experience headaches, the most common and mildest neurological manifestation34.
In this study, we found that users of X had greater interactions when the content of the tweets was related to headache, likely because headache is the most common neurological disorder in the population28. Many studies have demonstrated the use of social media platforms to share experiences with headaches35,36. Additionally, there are multiple reports linking headaches with social media use29, as somatic symptoms, including headaches, have been found primarily in patients with problematic use of social media29,37.
Regarding the temporal evolution of the disease, our data showed that the number of tweets about fibromyalgia decreased between the second and third trimesters of 2019, reaching its lowest level in the third trimester of 2020 in the context of the SARS-CoV-2 pandemic. The uncertainty of the SARS-CoV-2 pandemic caused an abrupt interruption of treatment for patients suffering from chronic pain, resulting in potential unintended harm. For example, in the fibromyalgia population, there is an association between negative emotions ("fear" or "sadness") and less information dissemination, although user interaction is more common. Regarding the effects of the pandemic, studies confirm that COVID-19 has altered the daily functioning of departments by prioritizing hospital services exclusively for life38. This not only occurred with fibromyalgia; for instance, research has demonstrated the impact of the pandemic on the treatment of neurological diseases such as multiple sclerosis, especially due to the high risk of initiating immunosuppressive treatments38,39 and delays or cancellations of electrodiagnostic studies38,40. On the other hand, there was a general reluctance to visit hospitals among the population. We can speculate that the incidence of neurological emergencies did not decrease during the COVID-19 pandemic but rather that differences in the number of patients were due to alterations in public health policy and users' reluctance to visit hospitals38. However, longer-term follow-up studies are needed to evaluate the lasting consequences of the pandemic on the prevalence of neurological diseases and the treatment of patients with chronic neurological disorders38.
It is relevant to recognize the association of temporal evolution in the analysis of tweets about fibromyalgia and headache with the SARS-CoV-2 pandemic. The literature describes the persistence of a wide range of symptoms long after the acute phase of severe acute respiratory syndrome caused by SARS-CoV-241,42, including extreme fatigue, musculoskeletal pain, headache, sleep disorders, anxiety, and depression24,42,43. This clinical picture is associated with poor quality of life and severe deterioration of functional capacity and is known as post-COVID-19 syndrome; these conditions may resemble fibromyalgia because they meet the same diagnostic criteria. Similarly, the exacerbation or onset of fibromyalgia symptoms can occur during or after SARS-CoV-2 infection or due to numerous and persistent stressors imposed daily by the pandemic environment44. Awareness among the general population and healthcare professionals about the development of this syndrome may have led to a decrease in interest in fibromyalgia. However, in the same context, publications and interactions about headache increase, because it is part of this syndrome.