Sensory neurology: A new neurology subspecialty and opportunity

Sensory abnormalities represent a prevalent chief complaint within clinical neurology, which is an essential but neglected domain in neurology. This subset of individuals presents substantial challenges for clinical diagnosis and treatment. Hence, there is an urgent need to focus on the clinical diagnosis and treatment of patients experiencing sensory abnormalities. Sensory Neurology: A Dawn of New Subspecialty in Neurology With the ongoing modernization of medicine, subspecialization has emerged as an inevitable trend. This transformation is primarily motivated by the imperative to deliver more precise and higher quality medical care, particularly in response to surges in patient numbers in specific symptomatic categories and the inadequacy of existing diagnostic and treatment approaches. Currently, subspecialties in neurology include epilepsy, brain injury medicine, pain medicine, neurocritical care, neurodevelopmental disorders, neuromuscular medicine, movement disorders, and vascular neurology. The advent of these subspecialties has not only facilitated standardized diagnosis and treatment of related diseases but also contributed to the dissemination and perpetuation of scientific research and knowledge.[1] Here, we propose sensory neurology as a new neurology subspecialty to enhance health care quality, focusing on prioritizing patient outcomes. Sensory Symptoms, Sensory Conduction, and Neurotransmitters Generally speaking, sensation includes somatosensory, vision, hearing, balance, smell, and taste. However, this classification is far from meeting the clinical needs. In clinical practice, patients’ complaints of sensory abnormalities go far beyond the sensory organ-based categorization of discomfort. Therefore, the clinical patients’ great need has prompted us to think about how to change the current understanding of the sensory system. The main complaints of patients with sensory abnormalities encompass a broad spectrum of complex clinical manifestations,[2–4] such as chronic pain, headache, dizziness, tinnitus, numbness, burning sensation, pulling sensation, electric shock sensation, gas sensation, cutting sensation, pricking sensation, itching, taste change (spicy, bitter, salty, sweet, etc.), pulsating sensation, wriggling sensation, bloating, fullness, hunger, roaming sensations, etc. While some sensory symptoms may be attributed to conditions like stroke and peripheral neuropathy, system diseases, and localized tissue or organ diseases, post-treatment residual sensory symptoms may even extend to broader areas, presenting challenges in control.[2,4] Furthermore, a considerable proportion of patients’ sensory symptoms cannot be explained through traditional neuroanatomical pathways.[3] Patients afflicted by these conditions often experience considerable suffering and repeatedly seek medical care; however, they frequently face oversight due to the absence of abnormal routine examination results or are misdiagnosed as having mental disorders, resulting in significant psychological and lifestyle burdens.[3] In later stages, patients exhibit illness-like behaviors, such as compulsive behaviors, which can further complicate treatment due to repeated medical consultations without relief.[3,4] This phenomenon suggests that, aside from currently explainable neurological diseases, a substantial category of disorders may be linked to functional abnormalities in the nervous system, particularly in the pathways of sensory conduction and the imbalance or improper regulation of neurotransmitters.[5] The advent of functional brain science has facilitated the study of changes in neurotransmitters.[6] As fundamental modulators of nervous system function, neurotransmitters profoundly influence emotions, cognition, and sensations. From the molecular to the system level, neurotransmitter imbalance is associated with various somatic symptoms, including sensory abnormalities that are difficult to explain by traditional examination methods, such as irritable bowel syndrome.[7] Accumulating evidence-based data indicates that multiple medications targeting norepinephrine and serotonin can effectively alleviate some symptoms of sensory abnormalities.[5,8] More specialized research and treatment guidelines for sensory abnormalities are needed in the current field of neurology. The cerebral regions implicated in these symptoms are intricately complex, and erroneous diagnoses can lead to inappropriate treatment strategies. Thus, accurate diagnosis and treatment of sensory abnormalities require more profound neuroscientific knowledge, interdisciplinary collaboration, and more effective clinical interventions and detection methods. Difficulties, Challenges, and Etiological Diagnoses Establishing a new subspecialty—sensory neurology—presents numerous difficulties and challenges. First, there is concern that existing medical institutions and professionals may need additional time and training to adapt to the diagnostic and therapeutic techniques of this new subspecialty, given the lack of experienced educators and a well-established curriculum. Second, certain concepts within this specialty might overlap with those in existing neurology subspecialties, potentially leading to confusion in research directions and difficulties in resource allocation. Furthermore, the diagnosis of sensory abnormalities relies heavily on patient self-reports, which are highly subjective. This reliance impedes the objective and standardized quantification of sensory anomalies due to the limitations of current technological methods. At present, assessment tools such as pain scales often lack the requisite sensitivity and specificity. For the subspecialty of sensory neurology to mature, with recognition of the imperative for precision in evaluating these elusive symptoms, more objective diagnostic standards are need to be established. In light of these challenges, there is a pressing need to establish reliable, sensitive, valid, and clinically practical clinimetric models to measure sensory abnormalities in neuropathic syndromes, much like the development of scales for neuropathic pain.[9] Quantitative sensory testing allows for objective measurement of skin responses to stimuli, such as temperature and pressure, thereby enhancing our diagnostic capabilities.[10] Additionally, conducting well-trained, effective, patient-centered interviews[11] and neurological examinations by gathering clinical information in an empathic and thoughtful manner is another invaluable professional conduct for the subspecialist. Rapid advancements in neuroscience have offered promising avenues for the progression of sensory neurology. Innovative methods, such as functional magnetic resonance imaging (fMRI), enable observing brain activity in response to specific sensory stimuli.[12] In the future, physicians should prioritize integrating patients’ subjective reports with findings from evolving digital technologies to increase diagnostic accuracy. This combination has the potential to refine diagnostic precision, overcome the current limitations posed by subjectivity, and usher in a new era in the understanding and management of sensory abnormalities within the neurology field. Despite the challenges these patients pose in terms of the categorization of their symptoms within the conventional framework of neurological diseases, their etiological diagnosis is classified as “MIDNIGHT × VIP” [Supplementary Table 1, https://links.lww.com/CM9/C154], where each letter corresponds to a potential etiology: M-metabolism, I-inflammation/immunity, D-degeneration, N-neoplasm, I-infection and I-idiopathic diseases, G-gland, H-hereditary, T-toxicity/trauma, ×-functional or unrealized cause, V-vascular, I-iatrogenic, and P-psychogenic. The symbol “×” emphasizes a substantial category of sensory abnormalities intricately linked to functional aberrations in the nervous system. Mechanisms and Treatments When reexamining the underlying mechanisms of sensory abnormalities, extensive research should be conducted from the molecular to the system level. Subtle changes in neurotransmitters and neural circuits–often overlooked by many current mechanistic theories–are likely the fundamental causes of sensory abnormalities.[13] Advanced molecular biology techniques, including gene editing and proteomics, enable the exploration of gene and protein changes leading to sensory abnormalities.[14] Moreover, the ongoing development of neuroimaging techniques, such as fMRI, positron emission tomography, and magnetoencephalography, has the potential to reveal how the networks responsible for processing sensory information in the brain change in functional disorders.[15] Electrophysiological techniques also provide valuable spatiotemporal information by recording brain and peripheral nerve activity.[16] While traditional pharmacological treatments, such as those targeting specific neurotransmitter systems, have shown some effectiveness, future treatment strategies might incorporate personalized medicine, targeted therapies, and novel neuromodulation techniques. Neuromodulatory methods, including transcranial magnetic stimulation, transcranial electrical stimulation, and deep brain stimulation, offer new therapeutic avenues for refractory sensory abnormalities.[17] A Call to Action Actually, there is a pressing need to establish a sensory neurology subspecialty; this need is driven by the demands of patients, societal expectations, and the evolving landscape of diagnosis and treatment.[2,3,5] Throughout the evolution of this subspecialty, we anticipate the emergence of innovative diagnostic and treatment models that will prioritize the correlation between patients’ subjective experiences and objective examination findings. This approach aims to enrich our understanding of how the nervous system integrates sensory information across multiple levels. Establishing a sensory neurology subspecialty not only complements the existing neurology specialty system but also represents an innovation in current treatment strategies. This approach is poised to propel the rapid advancement of neurology and brain science, fostering a transition from symptom management to etiological treatment. This shift is crucial for cultivating specialized talent in sensory neurology subspecialization, aimed at promoting a more comprehensive and systematic development of diagnostic and therapeutic skills to meet clinical demands. The future of neurology is characterized by intricate, nuanced, and perpetual evolution. In this era of high-value, patient-centered care systems, the adaptability of training to meet the expanding needs of the patient population is an asset, not a drawback. Through collaborative interdisciplinary efforts, we can collectively propel the development of the subspecialty of sensory neurology, benefiting a substantial population of patients predominantly presenting with sensory abnormalities. Acknowledgments The author indebted to Xiaolei Liu and Xinqi Huang for their assistances with the organizing references in this view. Funding This work was supported by grants from the National Natural Science Foundation of China (No. 82371490), the National Key R&D Program of China (No. 2022YFC2503901), the Beijing Health System Leading Talent Grant (No. 2022-02-10), and the “Dengfeng” Talent Training Program of Beijing Hospitals Authority (No. 2024-05-10). Conflicts of interest None.