Response to the letter entitled “The conceptual field of medically unexplained symptoms and persistent somatic symptoms”

To the Editor,

We read the article of Teodoro and Oliveira carefully, written in response to our published article titled “Repetitive transcranial magnetic stimulation (rTMS) in management of medically unexplained symptoms (MUS): Challenges and scopes.” ¹ We are grateful to the authors for initiating a debate on the conceptualization of the term “Medically unexplained symptoms (MUS).” We agree with the authors’ explanations and arguments supported by evidence that “MUS” and “Functional neurological disorders (FND)” are not the same entities as there are many conceptual and phenomenological differences between these two entities. Teodoro and Oliveira have attempted to discuss the phenomenological and conceptual differences between MUS and FND in a more elaborate manner, which we have not done in our article. ¹ Here, we want to emphasize to the readers that the aim of our article was not to explain the concept of MUS or FND, rather it was to discuss the scope and opportunities related to the use of neuromodulation techniques like rTMS in the management of MUS. We never denied the relevance of pharmacological, psychological intervention, and other interventions including rehabilitation strategies in the management of MUS or FND. We did not discuss those interventions in detail due to the word constraints of a letter to the editor and more so it was not the aim of the article.

The similarities between MUS and FND are more than the differences they have; hence, they are considered an overlapping phenomenon, and the terms MUS and FND have been used interchangeably in the literature despite debates and controversies. ^{2 - 4} MUS refer to any symptom (either neurological or nonneurological), that cannot be explained by a medical (physical or systemic) illness; whereas FND refers to any neurological symptoms that are present without any apparent neurological disorder (which is more of a subset of MUS). ^{3 , 5}

Though it is debatable to use the term MUS due to several reasons as cited by Teodoro and Oliveira and several other researchers, ^{3 , 5} the fact is—it is a commonly encountered entity and commonly used term in medical research, clinical practice, and therapeutic communication. When the term MUS is used in the research literature, a reader (whether researcher, clinician, educated patient, or caregiver) can know, what the term refers to. MUS are not a standard diagnostic category, and it refers to most psychiatric disorders enlisted under somatoform disorder (illness anxiety disorder) and conversion disorder. We again thank Teodoro and Oliveira for elaborating on the conceptual dimension of MUS and FND. Again, we want to emphasize that neuromodulation has a scope in dealing with MUS and further research should explore the opportunities of neuromodulation techniques for managing MUS.