How Can Pain Be Recognized When Words Fail?

The monitor emits a steady beep as a nurse inserts a thin needle into the tiny arm of Claudia, a premature infant weighing 900 g. She does not cry. She is too immature and tired to do so. Instead, she furrows her brow, her pulse quickens, and she arches her legs slightly. These small gestures signal pain, even though she cannot say a word. The scene could take place in any neonatal unit and capture one of medicine’s greatest challenges: recognizing suffering when a patient cannot say that they are in pain.Medicine can measure parameters such as glucose, blood pressure, and oxygen saturation with great precision; however, pain cannot be measured in the same way. Pain assessment depends largely on a patient’s ability to describe what they are feeling, where it hurts, and how severe the pain is, often using a scale of 1-10.However, what happens when a patient cannot provide the answer? How can clinicians prevent suffering when pain signals are difficult to interpret? Every day, infants, children with developmental disorders, patients with dementia, and sedated patients depend on others to recognize signs that may not be obvious. Recognizing pain in these patients is a major challenge in pain medicine because identifying suffering is the first step toward treatment.Pain MeasurementPain is a subjective experience. The International Pain Association defines it as “an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.” This definition clarifies that pain is not solely the result of physical injury, but also involves biological, psychological, and social factors.Therefore, the scientific community has long advocated assessing pain as the fifth vital sign. However, pain remains the only vital sign without a universal objective marker. Assessments continue to rely on patient self-reporting, clinical observation, and professional judgment. These approaches are essential but can be insufficient when a patient cannot communicate.“Describing pain only in terms of its intensity is like describing music only in terms of its loudness.” This famous quote by Canadian pediatric pain researcher Carl L. von Baeyer highlighted the multidimensional nature of pain. This comparison illustrates the difficulty of capturing such a complex experience with a single number.This uncertainty is also a part of the daily experience of healthcare professionals.“As physicians, we often feel helpless to understand how our patients are experiencing pain and whether treatments are working,” said Julia Finkel, MD, pediatric anesthesiologist and director of Pain Medicine Research at the Sheikh Zayed Institute for Pediatric Surgical Innovation at Children’s National Hospital, Washington, DC, in press news release.Her team is developing a device designed to provide objective measures of pain. According to Finkel, current pain scales do not identify the source of pain or precisely guide treatment, implying that clinical decisions may sometimes rely on trial and error. This limitation is particularly important when patients cannot describe what they are experiencing and their pain may go unrecognized.Claudia was unable to say that she was in pain. Until recently, newborns were thought to experience little pain because their nervous systems were immature. The evidence now shows otherwise. Even extremely premature infants experience pain, and repeated exposure to painful procedures without adequate pain management can affect their stress responses, neurologic development, and sensitivity to pain later in life.However, scientific knowledge does not always translate into clinical practice. A multicenter study conducted in 30 Spanish neonatal intensive care units found that two thirds (66.7%) did not systematically use a clinical scale to assess pain, while only 16.7% of newborns had been assessed at least once with a validated scale during their hospital stay.Pain assessment therefore continues to rely more on clinicians’ experience and judgment than on standardized tools, even though scientific organizations such as the Spanish Group for the Study of Pediatric Pain, a working group under the Spanish Association of Pediatrics, have recommended these tools for years.There are many opportunities to detect pain. A premature infant admitted to a neonatal intensive care unit may undergo a median of 16 potentially painful procedures per day, including blood draws, intravenous insertions, aspirations, and punctures, often over several weeks. Although individual procedures may appear minor, their cumulative effects can affect neurodevelopment.Pain Expressed Through BehaviorGrowing older individuals does not necessarily solve the problem. Learning to speak does not mean that young children can easily describe their pain. Children may not know how to pinpoint abdominal pain, describe headaches, or explain a stabbing sensation. Pain may first become apparent through behaviors such as increased crying, stopping play, refusing to walk, or becoming upset when picked up. At these ages, facial expressions, posture, movement, and crying can provide as much information as a child’s description of pain. Parents’ knowledge of their children’s usual behavior can also provide valuable clinical information.Marcos is 9 years old and has autism spectrum disorder. For several days, he had been sleeping poorly, refusing to put on his shoes, and hitting his head more often. His parents could not determine what is wrong until an x-ray revealed a broken toe. The problem is not that Marcos does not feel pain; he just expresses it differently.The same applies to many children with intellectual disabilities, severe developmental disorders, and significant communication difficulties. In these children, pain may manifest through behavioral changes. Children may stop participating in activities once enjoyed, have difficulty sleeping, become socially withdrawn, become more irritable, or show an increase in repetitive behaviors. These changes can contribute to the overlooked pain.A 2026 review published in Frontiers in Pain Research concluded that these children remain at a high risk for underreporting pain because conventional scales are not always adequate and observational tools are used inconsistently. The authors emphasized that understanding how an individual child expresses pain is as important as knowing the child’s diagnosis.A similar issue occurs in children with autism. Although autism was previously thought to be associated with reduced pain perception, recent evidence indicates that children with autism experience pain but may communicate differently. This can increase the risk that pain will go unrecognized, according to a 2025 study published in the Multidisciplinary Pain Journal.Unbelieved PainAt times, the problem is no longer finding the right words but getting someone to believe them. Rodrigo is 15 years old and has been describing back pain that prevented him from finishing basketball practice. Tests show no injury, and over time he has heard the same message at home, at school, and even in the doctor’s office: “You’re probably exaggerating.” Eventually, he stops talking about the pain, not because it has disappeared, but because he is tired of having to justify it.This experience is common among children and adolescents with chronic pain. A qualitative review published in Patient Education and Counseling found that in addition to physical pain, many young patients experience distress when their pain is questioned, their concerns are dismissed, and family members, teachers, and healthcare professionals doubt the reality of their suffering.Many adolescents experience distress from a lack of understanding, social isolation, or having to give up activities they enjoy, and these effects can be as disabling as the pain itself. The authors concluded that suffering does not always worsen as pain becomes more intense. It can also worsen when no one acknowledges that pain exists.Pain and MemoryAt the other end of life, the ability to communicate about pain gradually fades. Every morning, Carmen resists getting out of bed, and her daughter believes that her dementia is progressing rapidly because Carmen has become increasingly irritable, sleeps poorly, and refuses help to get dressed. Days later, the family discovered that hip osteoarthritis has been causing intense pain for weeks, pain that Carmen can no longer explain.As dementia progresses, the ability to locate pain, describe it, or ask for help diminishes. Instead, pain may be signaled by subtle changes, such as grimacing with movement, sleep disturbances, resistance to care, loss of appetite, or unexpected irritability.Reviews by the International Association for the Study of Pain and the European Pain Federation estimated that 40%-80% of patients with dementia experience pain regularly. However, pain remains underdiagnosed because these signs are often attributed to the progression of dementia instead of being attributed to a treatable source of pain.Technology ListensAfter centuries of asking patients about pain, researchers are now exploring objective indicators that could help identify pain when words are insufficient. One approach involves blood biomarkers, including proteins, metabolites, and inflammatory mediators, which may help identify specific types of pain or predict whether acute pain will become chronic. Another approach focuses on involuntary physiologic responses that may help detect pain.One of the most innovative projects is the Nociometer, a device developed by Finkel that analyzes changes in pupil diameter to estimate the intensity and characteristics of pain in patients who cannot communicate, including sedated and potentially pediatric patients in the future.AI may also help clinicians recognize pain that is difficult to detect. Researchers are developing algorithms that analyze facial micro-expressions, body movements, and physiological parameters to identify patterns that may not be apparent to the human eye. A 2025 systematic review published in the Exploration of Medicine, which analyzed 25 studies, concluded that these tools could improve pain assessment in patients who are unable to communicate. However, broader clinical validation is needed before they can be used in routine clinical practice.The next step may be to combine these different approaches rather than to develop a single better tool. Multimodal models, such as the PainFormer, which is still in the research phase, combine images, biomarkers, physiological parameters, and clinical variables to provide a more comprehensive and personalized assessment. The goal is not to find a single “pain thermometer” but to combine various sources of information to assess an experience that remains deeply human and subjective as accurately as possible.Clinical ChallengeDespite these advances, the main barrier to improving pain assessment may not be technology, but the organization of care. A 2025 review published in BMC Anesthesiology identified lack of specific training, communication difficulties, poor implementation of protocols, organizational challenges, and limited clinical time as the main obstacles. Technological limitations were considered less important.The paradox is clear: While medicine is developing algorithms that can interpret facial expressions, healthcare professionals do not always have sufficient time to observe those expressions. Recognizing pain requires not only better tools but also the knowledge to use them and the time to observe patients carefully.The monitor continues to beep next to Claudia’s incubator. She still cannot say what is hurting her. Marcos expresses pain through his behavior. Rodrigo found the words, but no one believed him. Carmen has gradually lost the ability to express hers. Age, illness, and the way pain manifests may differ, but the challenge remains the same: recognizing suffering when words fail. Perhaps in the future, an algorithm, biomarker, or camera will be able to accurately recognize pain. Until then, one of the most valuable tools will remain a healthcare professional who takes time to pause, observe, and listen, even when pain has no voice.This article was translated from El Médico Interactivo on Univadis, part of the Medscape Professional Network.