When to consider neuromodulation for fnd

Considering neuromodulation in functional neurological disorder (FND) usually arises when specific clinical features suggest that standard treatments have not been sufficiently effective or that the symptom profile may particularly benefit from brain-targeted interventions. One key feature is the persistence of disabling symptoms despite an adequate trial of first-line approaches such as clear diagnostic explanation, physiotherapy or occupational therapy tailored for FND, and psychologically informed treatments, for example cognitive behavioral therapy or psychodynamic approaches. When motor symptoms like functional weakness, gait disturbance, or tremor remain severe enough to limit ambulation, self-care, or employment after these interventions, clinicians may consider whether tools like transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) could help modify the abnormal patterns of brain network activity associated with FND.

Another important clinical feature is the presence of specific motor phenomena that appear to involve aberrant cortical excitability or network integration. Patients with functional limb weakness who display inconsistent strength, give-way weakness, or positive bedside signs such as Hoover’s sign may still be considered for neuromodulation if these signs coexist with chronic functional deficits that are not improving. Similarly, functional movement disorders characterized by tremor, dystonia, jerks, or gait abnormalities that show internal inconsistency or distractibility, but remain highly disabling, may be candidates. In these cases, clinicians look for a relatively stable pattern of symptoms over time rather than chaotic, rapidly shifting presentations, because stable symptom patterns make it easier to target specific motor or premotor regions with TMS or other modalities.

Patients with functional seizures (also called dissociative seizures or psychogenic nonepileptic seizures) can also present with features that prompt consideration of neuromodulation. These include high seizure frequency causing repeated emergency visits, hospitalizations, or prolonged loss of work or school days, despite appropriate diagnostic disclosure, psychological therapy, and safety planning. When functional seizures coexist with prominent mood or anxiety disorders, chronic pain, or sleep disturbances, clinicians may ask whether neuromodulation directed at mood and arousal networks could indirectly reduce seizure frequency and severity. However, these interventions are usually considered only after video-EEG or comparable evaluation has confirmed the diagnosis and excluded epileptic seizures.

Chronicity and refractoriness are central considerations. Patients who have had FND symptoms for many months or years, with clear functional impairment and limited response to evidence-based multidisciplinary treatment, may be more likely to be evaluated for neuromodulation. Recurrent falls, loss of driving privileges, or inability to maintain work or caregiving roles despite sustained engagement in therapy are features that highlight substantial impact on quality of life. In this context, neuromodulation is viewed as a potential means to “reset” or reshape maladaptive brain networks, not as a replacement for physical or psychological therapies, but as an adjunct that may enhance their effectiveness.

Coexisting psychiatric and cognitive features also influence consideration. Prominent depression, anxiety, post-traumatic stress symptoms, or emotional dysregulation are common in FND and can worsen functional symptoms. If these conditions have proven resistant to standard pharmacologic and psychotherapeutic approaches, and if they are strongly intertwined with the onset or maintenance of FND symptoms, there may be a rationale for neuromodulation targeting regions implicated in mood and emotion regulation, such as the dorsolateral prefrontal cortex. Patients who describe persistent negative self-beliefs, excessive symptom-focused attention, and difficulty shifting attention away from bodily sensations may represent a subgroup in which modulating prefrontal and parietal networks could theoretically facilitate better engagement with psychological treatment.

Another feature involves sensory and pain manifestations. Some people with FND experience functional sensory loss, paresthesias, or complex pain syndromes that do not conform to typical neuroanatomical patterns. When these symptoms lead to severe disability and have not responded adequately to rehabilitation and pain management strategies, neuromodulation may be explored as a way to influence cortical sensory processing and pain modulation circuits. Patients with central sensitization, widespread pain, or overlapping conditions like fibromyalgia may have altered brain network connectivity that could, in theory, be amenable to brain stimulation, though decisions are made cautiously due to variable response and limited research specifically in FND-related pain.

Clinical features suggesting a high level of emotional or physiological arousal may also guide consideration. Individuals who report episodes of overwhelming autonomic activation, such as surges of heart rate, breathlessness, or dizziness accompanying their functional symptoms, may have dysregulated interactions between limbic, autonomic, and motor systems. In such scenarios, some clinicians contemplate neuromodulation strategies that might influence these networks, including noninvasive or implanted vagus nerve stimulation, although the role of these techniques in FND remains under investigation. Features like marked startle responses, heightened stress reactivity, or symptoms tightly linked to interpersonal stressors can signal a system that may benefit from interventions targeting emotion and arousal circuits.

Functional cognitive symptoms, often called functional cognitive disorder, can coexist with or resemble FND. Here, features include fluctuating memory complaints, difficulties with concentration or word-finding, and a mismatch between subjective impairment and relatively normal objective testing. In patients whose cognitive complaints are entrenched, distressing, and tied to functional motor or seizure-like symptoms, neuromodulation may be discussed if attentional and executive control networks appear to be central to the symptom pattern. The goal would be to support re-establishing more adaptive cognitive control rather than to “restore” damaged tissue, since by definition structural brain damage is absent in FND.

Patterns of symptom triggering and maintenance provide further clues. Symptoms that are closely linked with learned patterns of movement, conditioned fear responses, or maladaptive habits might theoretically respond to neuromodulation if combined with concurrent retraining. For example, a person with a long-standing functional tremor that worsens in specific postures or contexts yet is partially suppressible with distraction may benefit when neuromodulation is integrated into physiotherapy designed to retrain movement and reduce tremor-related threat perceptions. The combination of consistent symptom triggers, relative stability, and partial responsiveness to distraction can support targeted stimulation parameters and timing.

Clinicians also pay attention to the patient’s level of insight and willingness to engage in active rehabilitation. Neuromodulation is most likely to be considered when patients understand the functional nature of their symptoms, recognize that no progressive structural damage is present, and are motivated to participate in therapies that require effort and practice. Features such as flexible thinking about illness beliefs, openness to psychological formulations, and a history of partial but incomplete response to therapy support the idea that neuromodulation might amplify existing gains rather than act as a stand-alone cure. In contrast, severe fixed beliefs that the condition must be purely structural, or complete refusal of noninvasive treatments, may predict poor engagement and limit the potential benefits of neuromodulation.

Safety-related clinical features are also central. Neuromodulation may be considered when FND symptoms pose clear risks that are not adequately controlled through conventional management. Examples include frequent uncontrolled collapses, severe gait instability leading to repeated injuries, or functional seizures that result in burns, fractures, or unsafe behaviors. In these situations, even a modest reduction in symptom frequency or intensity could significantly reduce harm, making the risk-benefit profile of neuromodulation more favorable. At the same time, clinicians must carefully assess the risk of reinforcing illness behaviors or creating unrealistic expectations about outcomes.

Patterns of comorbidity with other neurologic or psychiatric conditions can influence clinical decision-making. Features such as coexisting chronic migraine, refractory depression, obsessive-compulsive tendencies, or tinnitus, for which neuromodulation has an emerging or established role, might make it more appealing to consider a single intervention that could address multiple symptom domains. However, the presence of progressive neurologic disease, unstable medical conditions, or uncontrolled psychosis typically weighs against the use of neuromodulation for FND. Across these diverse clinical features, current evidence and research remain evolving, so each case requires individualized weighing of severity, chronicity, prior treatment response, and the specific symptom profile that might be most amenable to targeted modulation of brain networks.

Assessment and diagnostic workup before intervention

Before any neuromodulation approach is offered for functional neurological disorder, a careful and systematic assessment is essential to confirm the diagnosis, clarify contributing factors, and define realistic treatment goals. The primary aim is to ensure that symptoms are truly functional in nature, rather than manifestations of an undiagnosed structural, metabolic, or epileptic condition. This diagnostic certainty not only protects patient safety but also supports informed consent and appropriate expectations regarding what neuromodulation, such as TMS or tDCS, can and cannot achieve.

The process typically begins with a detailed clinical history. Clinicians explore the onset and evolution of symptoms, including any precipitating events such as physical injury, acute illness, psychological trauma, or significant life stressors. The timing and pattern of symptom fluctuation, relationships to situational triggers, and the presence of periods of remission or variability are documented. Particular attention is paid to internal inconsistency, distractibility, and context-dependent changes in symptoms, as these features are characteristic of FND and help differentiate it from fixed structural disorders. A clear history of previous treatments—physiotherapy, psychotherapy, medications, and any prior neuromodulation—is essential to gauge refractoriness and to assess how future interventions might be integrated.

A comprehensive neurologic examination is central to the workup. For motor symptoms, clinicians look for positive signs of FND, such as Hoover’s sign, collapsing or give-way weakness, incongruent gait patterns, entrainable or distractible tremor, and movement variability with changes in attention or posture. For sensory symptoms, they assess non-dermatomal or sharply demarcated sensory loss and inconsistent patterns across repeated testing. In functional seizures, observation of semiology that is atypical for epileptic events—such as prolonged duration, asynchronous movements, side-to-side head shaking, closed eyes, or preserved pupillary responses—supports the diagnosis. These positive signs help establish FND as a rule-in diagnosis rather than a diagnosis of exclusion, which is critical before neuromodulation is considered.

Ancillary testing is usually tailored to the symptom profile but often includes neuroimaging and, when indicated, electrophysiologic studies. Brain MRI is frequently obtained at least once to exclude structural lesions, demyelinating disease, or other major pathologies that could explain the presentation. In motor FND, routine nerve conduction studies and electromyography may be ordered to rule out peripheral neuropathy, myopathy, or motor neuron disease. When seizure-like episodes are prominent, video-EEG monitoring is the gold standard. Capturing typical events on EEG without epileptic discharges, alongside compatible clinical features, confirms functional seizures and helps avoid unnecessary antiepileptic medications. This objective documentation is particularly important before offering TMS, tDCS, or vagus nerve stimulation, as some modalities can lower seizure threshold and require clarity about coexisting epilepsy.

Psychiatric and psychosocial assessment forms another core pillar of pre-intervention evaluation. Many people with FND have co-occurring depression, anxiety, post-traumatic stress symptoms, somatic symptom disorder, or personality vulnerabilities that influence symptom expression and treatment response. A structured or semi-structured psychiatric interview, along with validated questionnaires when feasible, helps delineate these conditions and guides whether neuromodulation is being considered primarily for functional symptoms, for comorbid mood and anxiety syndromes, or for both. Understanding trauma history, current stressors, coping strategies, and social supports clarifies how neuromodulation should be timed and combined with trauma-informed psychotherapy, cognitive behavioral therapy, or other psychological interventions.

Cognitive screening is often useful, especially when patients report memory or concentration issues, or when functional cognitive disorder is suspected. Brief instruments such as the Montreal Cognitive Assessment or more detailed neuropsychological testing can reveal patterns of performance that support a functional rather than degenerative etiology, such as inconsistent effort, pronounced variability, or discrepancies between subjective complaints and objective performance. This information is used not to invalidate the person’s experience, but to tailor neuromodulation and rehabilitation strategies toward attentional control, executive function, and metacognitive awareness, rather than toward presumed neurodegeneration.

Functional assessment of daily activities and disability level helps define treatment priorities. Clinicians may use standardized scales for motor function, gait, balance, seizure frequency, and quality of life to establish a baseline before neuromodulation begins. Describing how symptoms affect walking, self-care, work, relationships, and leisure helps determine which domains should be targeted first and what degree of change would be clinically meaningful. For example, in a person with functional gait disorder, the objective may be to progress from wheelchair use to short-distance walking with aids, rather than complete normalization of gait. These baseline measures are also critical for subsequent evaluation of neuromodulation efficacy and for distinguishing true improvement from day-to-day variability.

Evaluation of prior and ongoing treatments is equally important. Before neuromodulation is pursued, clinicians review whether the patient has had a clear diagnostic explanation, education about FND, and access to specialized physiotherapy or occupational therapy that uses principles of motor retraining and graded exposure. They also consider the extent and quality of psychological therapy or psychiatric care. If these first-line interventions have been limited, unavailable, or inconsistently attended, the clinician may prioritize optimizing them before or concurrently with neuromodulation. This sequence respects current evidence and research suggesting that neuromodulation is best conceptualized as an adjunct to, rather than a substitute for, comprehensive multidisciplinary treatment.

Risk assessment is a mandatory component of the workup. For noninvasive techniques like TMS or tDCS, clinicians screen for contraindications such as a personal history of epileptic seizures, presence of certain implanted metallic devices in or near the head, unstable cardiovascular conditions, or pregnancy when safety data are limited. Invasive or implanted options like deep brain stimulation or vagus nerve stimulation require more extensive medical clearance, including cardiology and anesthesiology evaluation when appropriate. Medication review is essential, particularly for drugs that alter seizure threshold or interact with stimulation-induced neuroplastic changes. A history of severe adverse reactions to neurostimulation or high sensitivity to somatic sensations may also influence the choice of modality or the intensity of stimulation.

Assessment of psychological readiness and expectations is crucial before any neuromodulation plan is finalized. Clinicians explore the patient’s understanding of FND, their beliefs about the cause of symptoms, and their hopes or fears regarding brain stimulation. Unrealistic expectations—such as viewing neuromodulation as a quick cure or as a way to bypass active participation in rehabilitation—must be addressed. A collaborative discussion emphasizes that neuromodulation is intended to facilitate relearning, support engagement in therapy, and modulate dysfunctional brain networks, not to repair structurally damaged tissue. Patients are encouraged to articulate personal goals, potential barriers to adherence, and what kinds of changes would feel meaningful in their daily lives.

In complex cases, an interdisciplinary case conference can be particularly valuable. Neurology, psychiatry, psychology, physiotherapy, occupational therapy, and nursing professionals may review the case together to confirm the FND diagnosis, assess the balance of potential benefits and harms, and determine whether neuromodulation fits within the broader treatment plan. Such collaboration helps avoid fragmented care and ensures that if TMS, tDCS, or other methods are used, they are coordinated with simultaneous physiotherapy or psychotherapy sessions, rather than delivered in isolation. Agreement on symptom targets, outcome measures, and time frames among team members helps create a coherent care pathway.

Documentation and shared decision-making formalize the outcome of this workup. The clinician summarizes diagnostic findings that support FND, comorbidities, prior treatment history, and the rationale for or against neuromodulation. Potential risks, side effects, and uncertainties—particularly given that evidence and research in this field are still evolving—are explained in accessible language. If neuromodulation is pursued, a preliminary protocol is outlined, including number of sessions, stimulation parameters where known, concurrent therapies, and specific metrics by which success or lack of benefit will be judged. If neuromodulation is deferred, the assessment still guides alternative strategies and provides a basis for revisiting the option later, should clinical circumstances change.

Neuromodulation modalities and their mechanisms in fnd

Neuromodulation approaches considered in functional neurological disorder encompass several noninvasive and, more rarely, invasive techniques that aim to alter pathologic patterns of brain network activity rather than correct structural damage. Among the noninvasive methods, repetitive transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are the most frequently discussed in the context of FND. Both rely on the principle that targeted modulation of cortical excitability and connectivity can influence the expression of motor, sensory, and cognitive symptoms, especially when paired with active rehabilitation strategies that help consolidate more adaptive patterns of functioning.

TMS uses brief, high-intensity magnetic pulses delivered through a coil placed on the scalp to induce electrical currents in specific cortical regions. Depending on frequency and pattern, stimulation can increase or decrease cortical excitability and alter communication within broader functional networks. High-frequency stimulation (usually ≥5 Hz) tends to enhance excitability, whereas low-frequency stimulation (around 1 Hz) is more likely to produce inhibitory effects. In FND, protocols often target motor or premotor cortices contralateral to the affected limb in motor presentations, or prefrontal regions involved in emotion regulation and cognitive control when mood or functional seizures are prominent. The therapeutic rationale is to “reset” maladaptive patterns of motor planning, agency, and attention that are thought to underlie functional symptoms, while patients simultaneously engage in tasks or movements that reinforce normal motor output.

Beyond changes in simple excitability, TMS is believed to influence large-scale brain networks that are disrupted in FND, such as interactions among the motor system, limbic regions, and areas associated with self-referential processing and salience detection. Functional imaging and neurophysiologic studies in FND have demonstrated abnormal connectivity between motor regions and limbic or prefrontal circuits, suggesting that symptoms may arise from inappropriate weighting of emotional and attentional signals in motor execution. By modulating key nodes within these networks, TMS may reduce the overemphasis on symptom-related signals, enhance voluntary movement initiation, and facilitate a more integrated sense of agency over actions. When TMS is delivered concurrently with physiotherapy, patients can practice desired movements during periods of altered network activity, theoretically increasing the likelihood that new movement patterns are encoded and retained.

tDCS offers a related but technically distinct form of neuromodulation. It delivers a weak, constant electrical current through electrodes placed on the scalp, subtly shifting the resting membrane potential of neurons in underlying cortical regions. Anodal stimulation generally biases neurons toward depolarization and increased excitability, while cathodal stimulation tends to have the opposite effect. Unlike TMS, tDCS does not induce action potentials directly; instead, it primes networks so that their activity during subsequent tasks or therapies is altered. In FND, anodal tDCS is typically positioned over motor cortex or dorsolateral prefrontal cortex, with the aim of supporting motor relearning, enhancing top-down cognitive control, and modulating emotion regulation circuits that contribute to symptom persistence.

The mechanisms by which tDCS might assist in FND are tightly linked to its ability to influence synaptic plasticity over repeated sessions. Subthreshold changes in excitability during stimulation can, when combined with task performance, promote long-term potentiation-like or depression-like processes in synapses within targeted networks. This is particularly relevant for FND, where symptoms often reflect learned patterns of movement, attention, and bodily vigilance rather than fixed lesions. By making cortical networks more receptive to change at the time of physiotherapy, occupational therapy, or psychotherapy, tDCS may help “re-weight” maladaptive predictive models about movement and bodily sensations toward more realistic, flexible interpretations. Patients may, for example, experience temporary improvement in motor output or decreased symptom intensity during or immediately after stimulation, providing a window of opportunity to reinforce new behaviors and beliefs.

Another noninvasive modality considered for some FND presentations is noninvasive vagus nerve stimulation. Using surface electrodes applied to the auricular branch of the vagus nerve or to the neck region, this approach delivers intermittent electrical pulses designed to engage vagal afferent fibers. These fibers project to brainstem nuclei, including the nucleus tractus solitarius, and from there to widespread regions such as the amygdala, insula, and prefrontal cortex. In theory, modulating this pathway can influence autonomic regulation, arousal, and emotional processing, all of which are often dysregulated in FND. For individuals with functional seizures or prominent autonomic symptoms, noninvasive vagus nerve stimulation is hypothesized to stabilize fluctuations in arousal and reduce the likelihood of episodes triggered by sudden shifts in internal or external stress.

Implanted vagus nerve stimulation, though more established in treatment-resistant epilepsy and depression, has also been discussed in highly refractory FND cases, especially when functional seizures dominate the clinical picture and comorbid mood symptoms are severe. Its mechanism involves chronic intermittent stimulation of the left cervical vagus nerve via an implanted generator, leading over time to altered synaptic plasticity, neurotransmitter release, and functional connectivity across limbic and cortical networks. Because FND is not characterized by epileptic discharges, the rationale hinges less on direct anticonvulsant effects and more on potential normalization of dysregulated arousal and affective circuits that drive dissociative or seizure-like events. However, the invasiveness and risk profile of implanted devices limit their use to exceptional circumstances, and their role in FND remains exploratory.

Deep brain stimulation (DBS) represents a further step in invasiveness and is rarely considered in FND outside of research or exceptionally atypical cases. DBS involves stereotactic implantation of electrodes into specific deep brain structures, such as the globus pallidus internus, thalamus, or subthalamic nucleus, connected to an implanted pulse generator. In organic movement disorders, DBS can modulate aberrant firing patterns within motor circuits and restore more physiological network activity. Translating this mechanism to FND has been proposed in a very small number of cases where functional symptoms coexist with or resemble severe organic movement disorders, but the theoretical foundation is less clear given the absence of structural pathology. Speculative mechanisms include rebalancing dysfunctional connectivity between motor circuits and higher-order regions related to volition, salience, and emotion; nonetheless, ethical and practical concerns currently confine DBS to the margins of neuromodulation approaches for FND.

More broadly, all these neuromodulation techniques—TMS, tDCS, vagus nerve stimulation, and DBS—are thought to exert their effects through modulation of network-level dynamics rather than single-site activation or inhibition. FND has been associated in neuroimaging studies with abnormal activity in regions related to self-agency (such as the supplementary motor area), heightened engagement of limbic structures during symptom expression, altered connectivity between sensorimotor and prefrontal regions, and shifts in how salience and attention are allocated to bodily signals. Neuromodulation attempts to shift these patterns toward a configuration more typical of voluntary movement and flexible emotional regulation. Changes may occur not only at the primary stimulation site but also in distant areas connected via structural and functional pathways, emphasizing the importance of careful target selection based on each individual’s symptom profile.

The timing and context in which neuromodulation is delivered are as critical as the selection of modality and target. In FND, symptoms are highly sensitive to attention, expectation, and contextual cues, so applying stimulation in isolation from rehabilitation may have limited and transient effects. Many emerging protocols therefore synchronize stimulation with physiotherapy sessions, motor retraining exercises, or exposure-based psychological work. During stimulation, patients may be guided to practice specific movements that are usually impaired, to engage in tasks that challenge maladaptive beliefs about bodily fragility, or to rehearse strategies for managing triggering situations. This concurrent practice capitalizes on periods of heightened neuroplasticity, increasing the likelihood that changes in network activity translate into meaningful functional gains.

Different neuromodulation modalities also carry distinct sensory experiences and procedural characteristics that can influence response in FND. TMS produces audible clicks and scalp tapping sensations, which may initially be perceived as unusual or anxiety-provoking but can also signal to the patient that an active intervention is underway. tDCS, by contrast, is quieter and usually associated with mild tingling or itching under the electrodes, potentially making it more acceptable for individuals who are sensitive to loud sounds or sudden somatic sensations. Noninvasive vagus nerve stimulation may produce sensations of tingling or pulling in the ear or neck, and in some cases mild throat discomfort. These sensory aspects can shape expectations and engagement, which in turn may interact with placebo and nocebo effects; protocols therefore typically include careful explanation to reduce misinterpretation of benign sensations as harmful or as evidence of disease worsening.

From a neurochemical perspective, neuromodulation may influence the balance of key neurotransmitter systems involved in FND, including gamma-aminobutyric acid (GABA), glutamate, serotonin, dopamine, and norepinephrine. Repetitive TMS over prefrontal regions, for example, is known from other conditions to alter monoamine transmission and increase neurotrophic factors such as brain-derived neurotrophic factor, which can support synaptic remodeling. tDCS has been associated with changes in local GABA and glutamate concentrations, shifting the excitatory-inhibitory balance in targeted cortical areas. Because FND often involves heightened threat processing, excessive bodily vigilance, and difficulties inhibiting maladaptive responses, modulating these neurochemical systems indirectly may help recalibrate how emotional and sensorimotor information is processed and responded to.

Importantly, neuromodulation in FND operates within an explanatory framework that emphasizes learning, prediction, and agency, rather than hidden lesions. The goal is not to “fix damage” but to facilitate the unlearning of maladaptive patterns and the acquisition of new, more adaptive ones. When a patient with functional limb weakness experiences improved movement during TMS-augmented physiotherapy, the mechanism is conceptualized as an interplay between altered cortical excitability, updated expectations about movement capacity, and reduced fear of symptom exacerbation. Over repeated sessions, these experiences can consolidate into a revised internal model in which voluntary movement feels more controllable and less threatening, reducing the likelihood of relapse. Understanding neuromodulation as a tool that supports, rather than replaces, active participation helps align clinical practice with the underlying neuroscience of FND.

The diversity of neuromodulation modalities and their mechanisms underscores the need for individualized protocol design informed by the specific symptom constellation, comorbidities, and treatment history of each person with FND. For some, TMS targeting motor cortex paired with intensive gait retraining may be most appropriate; for others, prefrontal TMS or tDCS combined with psychotherapy focusing on trauma or cognitive restructuring may better address the dominant drivers of symptoms. In cases with marked autonomic dysregulation or functional seizures, noninvasive vagus nerve stimulation might be considered as an adjunct aimed at stabilizing arousal and reducing episode frequency. As evidence and research continue to expand, these mechanistic insights provide a framework for tailoring neuromodulation to the complex, network-level disturbances characteristic of functional neurological disorder.

Evidence base, benefits, and risks of neuromodulation

The current evidence base for neuromodulation in functional neurological disorder is growing but remains relatively limited compared with conditions such as major depressive disorder or epilepsy. Most published work consists of small randomized controlled trials, open-label series, case reports, and feasibility studies, with considerable heterogeneity in symptom targets, stimulation parameters, and concurrent therapies. Across these studies, repetitive TMS and tDCS have been examined most frequently, while noninvasive vagus nerve stimulation and implanted devices like vagus nerve stimulators or deep brain stimulation have only scattered reports. This means that while early research is encouraging for some symptom domains, neuromodulation is still considered an adjunctive and, in many settings, experimental option for FND rather than a standard therapy.

In motor FND—such as functional limb weakness and functional movement disorders—several small randomized and uncontrolled TMS trials suggest that stimulation over primary motor or premotor cortex can lead to clinically meaningful improvements in strength, gait, tremor, or dystonia-like posturing, especially when paired with physiotherapy. Some studies have used single or very low numbers of high-intensity motor cortex stimulations, finding rapid reversal of weakness or improvement in abnormal movements that persisted for days to weeks. Others have implemented multi-session high-frequency TMS combined with structured motor retraining programs. Effect sizes in these reports are often moderate to large, but methodological limitations—small sample sizes, variable blinding quality, and short follow-up—temper confidence in durability and generalizability.

For functional seizures, the evidence is more preliminary but growing. Pilot RCTs and open-label series have investigated high-frequency TMS over the dorsolateral prefrontal cortex, often borrowing protocols from depression treatment. These studies report reductions in seizure frequency and severity for some patients, along with improvements in depression and anxiety scores. However, many lack long-term follow-up and include heterogeneous populations, making it hard to determine which clinical profiles derive the greatest benefit. Some case series of noninvasive vagus nerve stimulation in functional seizures show potential decreases in episode frequency and emergency presentations, but these findings come from small, often uncontrolled cohorts and may be influenced by regression to the mean, placebo effects, and concurrent psychosocial support.

tDCS has been less extensively studied than TMS but offers intriguing early findings. Small controlled trials applying anodal tDCS over the motor cortex, often combined with motor retraining or gait-focused physiotherapy, have reported improvements in walking distance, balance, and limb strength in people with functional motor symptoms. These gains sometimes extend beyond the immediate treatment window, suggesting that repeated pairing of tDCS with active practice may promote durable plastic changes. In prefrontal tDCS paradigms, research has focused on mood, anxiety, and cognitive control in FND populations, with some studies indicating reductions in symptom-related distress, improved emotion regulation, and better engagement with psychotherapy. Nonetheless, heterogeneity in electrode montages, current intensities, and session numbers complicates cross-study comparisons and prevents firm recommendations about optimal protocols.

Evidence for implanted neuromodulation, such as vagus nerve stimulation or deep brain stimulation, in FND is restricted to isolated case reports or tiny series. In individuals with severe functional seizures accompanied by refractory depression or coexisting epilepsy, implanted vagus nerve stimulation has sometimes been associated with reductions in both epileptic and nonepileptic events, as well as mood improvement. It is difficult to disentangle effects on functional symptoms from improvements in comorbid conditions, reductions in overall healthcare contact, and intensive multidisciplinary follow-up that often accompanies device implantation. Reports of DBS in FND-like movement symptoms are exceptionally rare and generally involve mixed or ambiguous outcomes; the invasive nature, cost, and ethical questions surrounding its use in a non-degenerative, non-lesional condition mean that DBS is not currently recommended outside of carefully controlled research contexts.

One of the consistent themes across the neuromodulation literature in FND is that benefits are often greatest when brain stimulation is deliberately integrated with concurrent behavioral or psychological therapies. Studies that pair TMS or tDCS with specialized physiotherapy, occupational therapy, or cognitive-behavioral interventions tend to report more robust and durable functional improvements than protocols using stimulation in isolation. This supports the theoretical model that neuromodulation opens a time-limited “window of plasticity” during which patients can more readily adopt new movement patterns, cognitive strategies, and beliefs about their symptoms. When stimulation is delivered without structured opportunities to practice alternative behaviors, improvements may be shorter-lived or predominantly limited to subjective symptom ratings.

Benefits reported across neuromodulation studies in FND span several domains. In motor presentations, patients may experience increased limb strength, reduced abnormal movements, improved balance, and greater independence in activities of daily living. In functional seizures, some individuals report fewer episodes, shorter seizure duration, reduced need for emergency care, and enhanced sense of control over triggers and early warning signs. Mood and anxiety symptoms, which frequently co-occur with FND, often improve during prefrontal TMS or tDCS, potentially contributing indirectly to better coping and decreased functional symptom severity. Patients may also describe enhanced concentration, less fatigue, and a greater ability to participate in rehabilitation, even when objective motor changes are modest.

A less tangible but clinically important benefit is the shift in illness perception that neuromodulation can facilitate. Experiencing real-time changes during or soon after TMS or tDCS sessions can powerfully illustrate to patients that their nervous system is changeable and that voluntary movement or symptom modulation is possible. This can increase confidence in rehabilitation, reduce feelings of helplessness, and weaken rigid beliefs that symptoms necessarily indicate permanent damage. In some studies, such shifts in agency and expectation have been associated with sustained functional gains well beyond the formal treatment period, suggesting that cognitive and emotional reframing may be a key mediator of neuromodulation’s longer-term benefits.

Despite these potential advantages, neuromodulation carries risks that must be weighed carefully, particularly given the evolving state of evidence and research. For TMS, the most serious but rare adverse event is induction of an epileptic seizure, especially with high-frequency or high-intensity protocols, stimulation over certain cortical regions, or in individuals with preexisting seizure risk factors. Mild to moderate side effects such as scalp discomfort, facial muscle twitching, headache, and transient fatigue are common but typically manageable with parameter adjustments and supportive care. Some patients with FND are highly sensitive to bodily sensations or sound; for them, the clicking noise and tapping sensations of TMS can initially exacerbate anxiety, dissociation, or symptom focus if not adequately prepared and supported.

tDCS is generally considered low risk, but side effects such as tingling, burning, itching under electrodes, mild headache, and skin redness can occur. Rarely, misplacement of electrodes, excessive current, or inadequate skin preparation can lead to more pronounced discomfort or superficial skin irritation. In individuals with high health anxiety or somatosensory amplification, even minor tDCS-related sensations may be misinterpreted as evidence of harm or disease progression, potentially undermining trust and engagement. Careful education, gradual titration of current, and close monitoring during early sessions can help mitigate these risks.

Noninvasive vagus nerve stimulation can cause local discomfort at the stimulation site, throat tightness, coughing, voice changes, or transient changes in heart rate or blood pressure. While serious cardiac complications are rare with properly screened patients and appropriate devices, people with preexisting cardiac arrhythmias, syncopal episodes, or autonomic instability require particular caution. For implanted vagus nerve stimulation and DBS, surgical risks such as infection, bleeding, device malfunction, anesthesia complications, and long-term hardware-related problems must be considered. Additionally, stimulation can in some cases worsen mood, provoke anxiety, or lead to other neuropsychiatric changes, underscoring the importance of close multidisciplinary follow-up.

Beyond physical risks, there are psychological and behavioral downsides to consider. If neuromodulation is presented or perceived as a “last resort” or as the only legitimate biological treatment, it may inadvertently reinforce narrow biomedical narratives that neglect psychological, social, and developmental contributors to FND. Some patients may place excessive hope in TMS, tDCS, or vagus nerve stimulation, expecting a rapid cure without the effort of rehabilitation. When outcomes fall short of these expectations, disappointment can erode trust in clinicians and reduce motivation to pursue other evidence-based interventions. Conversely, a dramatic but short-lived improvement followed by relapse may fuel catastrophic interpretations or reinforce the belief that only high-tech interventions can control symptoms, potentially undermining long-term self-management strategies.

Another concern relates to potential iatrogenic effects specific to FND. Because symptoms are highly responsive to attention, suggestion, and contextual cues, poorly designed or inconsistently delivered neuromodulation may inadvertently strengthen maladaptive patterns. For example, if sessions are repeatedly scheduled during peak symptom times without concurrent retraining, patients may come to associate the clinic and technology with symptom activation, seeking stimulation as a passive relief rather than working on active coping or exposure. In some cases, focusing extensively on stimulus parameters, device readouts, or subtle bodily changes may increase symptom monitoring and health anxiety, counteracting therapeutic goals.

Ethical and resource considerations also shape the risk-benefit landscape. Neuromodulation equipment and expertise are often concentrated in specialized centers, and sessions can be labor-intensive and costly. Offering TMS or tDCS to individuals who have not yet had access to basic FND-informed education, physiotherapy, or psychotherapy may exacerbate inequities and misallocate resources toward technologically sophisticated but still experimental options. At the same time, withholding neuromodulation from carefully selected, severely affected patients who have exhausted standard care may be ethically challenging when early data suggest potential benefit. Transparent discussion of uncertainties, costs, and alternatives is therefore essential in shared decision-making.

Methodological limitations in the current research base further complicate risk-benefit assessment. Many FND neuromodulation studies have small samples, heterogeneous inclusion criteria, limited blinding integrity, and short follow-up periods. Sham conditions for TMS, tDCS, and noninvasive vagus nerve stimulation are imperfect, and expectancy effects can be potent in FND populations. Outcome measures vary widely, ranging from symptom scales and clinician ratings to objective motor performance and healthcare utilization, making cross-study comparisons difficult. Long-term data on relapse rates, durability of gains, and the impact of repeated courses of stimulation are sparse. These gaps mean that clinicians must extrapolate cautiously from available findings and remain transparent about the experimental nature of many protocols.

Balancing these factors, many experts currently conceptualize neuromodulation for FND as a promising but still adjunctive tool best reserved for individuals with well-characterized diagnoses, substantial impairment, and limited response to comprehensive multidisciplinary treatment. In such contexts, the potential benefits—increased mobility, fewer functional seizures, improved mood, greater engagement with therapy, and enhanced sense of control—may outweigh the relatively low physical risks when protocols are delivered by experienced teams. However, decisions are highly individualized, incorporating patient values, comorbidities, logistical feasibility, and readiness to participate actively in concurrent rehabilitation. Ongoing and future randomized trials, mechanistic studies, and longer-term follow-ups are needed to refine patient selection criteria, optimize stimulation parameters, and more clearly delineate the trade-offs between neuromodulation’s potential advantages and its risks in functional neurological disorder.

Practical considerations for implementing neuromodulation in care

Implementing neuromodulation in day-to-day care for functional neurological disorder requires deliberate planning across clinical, practical, and organizational domains. The process begins with identifying an appropriate care setting. Most TMS and tDCS interventions are delivered in outpatient specialty clinics, often affiliated with neurology, psychiatry, or rehabilitation services. When symptoms are very disabling—such as severe gait disturbance, frequent functional seizures, or inability to perform basic self-care—short inpatient or day-hospital programs may be better suited, as they allow close coordination of stimulation with intensive physiotherapy, occupational therapy, and psychological support. Whichever setting is chosen, it should have clear protocols for emergency response, monitoring of side effects, and communication among all professionals involved.

A central practical step is assembling a multidisciplinary team with clearly defined roles. Neurologists or psychiatrists typically provide diagnostic confirmation, determine suitability for neuromodulation, and prescribe stimulation parameters. Clinical neurophysiologists or trained TMS/tDCS operators administer stimulation and monitor acute responses. Physiotherapists and occupational therapists design motor retraining plans that dovetail with stimulation sessions, focusing on movements and functions most relevant to the individual’s goals. Psychologists or psychotherapists address illness beliefs, trauma, mood, anxiety, and coping, helping patients integrate and interpret changes they may experience during treatment. Case managers or social workers can assist with scheduling, transportation, insurance authorization, and workplace or school accommodations, ensuring that logistical barriers do not undermine adherence.

Thorough patient preparation is a cornerstone of successful integration. Before the first session, clinicians explain what neuromodulation is intended to do in FND—facilitating relearning and altering maladaptive network activity—using language that avoids both excessive technical detail and unrealistic promises. Patients are informed about what TMS, tDCS, or vagus nerve stimulation will feel like, how long sessions last, and what side effects to expect. Written materials and diagrams can reinforce verbal explanations, and some clinics use brief demonstration sessions with very low intensity stimulation to desensitize patients who are anxious or highly focused on bodily sensations. Clear discussion about the difference between experimental and established uses of neuromodulation, with reference to current evidence and research, supports informed consent and appropriate expectations.

Scheduling is another practical consideration that can influence outcomes. Many protocols for TMS and tDCS involve multiple sessions per week over several weeks, requiring coordination with work, caregiving responsibilities, and other medical appointments. To maximize the synergy between stimulation and rehabilitation, sessions are often scheduled so that neuromodulation precedes or coincides with physiotherapy or psychotherapy on the same day. For example, a patient might receive 30 minutes of TMS over motor cortex followed immediately by 45–60 minutes of gait training, or a tDCS session over prefrontal cortex directly before cognitive-behavioral therapy targeting symptom-related fears. This sequencing is designed to exploit periods of heightened neuroplasticity and increase the likelihood that behavioral changes consolidate.

Developing an individualized treatment plan involves selecting symptom targets, stimulation parameters, and concurrent therapies based on the patient’s specific presentation. For functional limb weakness, high-frequency TMS or anodal tDCS over the contralateral motor cortex is often paired with graded strength and coordination exercises that emphasize automatic, rather than effortful, movement. For tremor or jerky movements, protocols may focus on premotor or supplementary motor areas while therapists shape movement patterns using strategies such as rhythm, distraction, or dual-task training. When functional seizures or predominant mood and anxiety symptoms are present, prefrontal targets are more likely, with psychotherapists working on emotion regulation, exposure to triggers, and reframing of catastrophic thoughts. Patients with marked autonomic dysregulation might be considered for noninvasive vagus nerve stimulation while practicing paced breathing, grounding techniques, or interoceptive exposure.

Setting realistic, concrete goals is essential to guide treatment and prevent disillusionment. Goals should be functional and measurable, such as walking unassisted for a certain distance, returning to part-time work, reducing emergency department visits for functional seizures, or independently performing specific household tasks. Symptom reduction (for example, fewer episodes or lower intensity) is important, but improved participation in meaningful roles often better reflects real-world benefit. Shared decision-making involves identifying which outcomes matter most to the patient and agreeing on time frames for reassessment, commonly after a defined course of sessions (for instance, 10–20 TMS or tDCS treatments).

Monitoring progress requires a blend of subjective and objective measures. Symptom diaries can capture frequency and triggers of functional seizures, collapses, or motor episodes. Standardized rating scales for motor function, gait, balance, mood, anxiety, and quality of life provide quantitative benchmarks. Video recordings of walking, limb movements, or task performance at baseline and at key intervals can visually document change and are often compelling for patients, reinforcing recognition of gains that may feel subtle day to day. Regular review of these data with the patient helps validate progress, highlight plateaus or setbacks, and adjust the treatment plan accordingly.

Safety monitoring must be integrated into routine workflows. For TMS, staff screen before each session for new medications, sleep deprivation, intercurrent illnesses, or any events that might alter seizure threshold. They confirm that hearing protection is used, coil placement is correct, and stimulation intensity is consistent with the prescribed protocol. For tDCS, operators inspect the skin, ensure good electrode contact, and start stimulation at a low intensity before ramping up to the therapeutic dose, watching for discomfort or unusual sensations. For noninvasive vagus nerve stimulation, clinicians check for signs of excessive bradycardia, dizziness, or exacerbation of autonomic symptoms, and adjust duty cycles or intensity when needed. Clear algorithms for handling adverse events, including when to pause or discontinue treatment, should be established in advance.

Because attention and expectation strongly influence FND symptoms, the way staff respond to symptom fluctuations during treatment can shape outcomes. When patients experience transient increases in tremor, weakness, or dissociative episodes during or after neuromodulation, clinicians avoid dramatizing these changes as signs of harm. Instead, they contextualize them as temporary fluctuations in a sensitive system undergoing retraining, while still taking patient distress seriously and ensuring safety. Staff are trained to reinforce messages about resilience, adaptability, and active coping, redirecting conversations away from detailed analysis of every bodily sensation and toward engagement with rehabilitation tasks and valued activities.

Coordination with primary care and other community providers is important for continuity. Before initiating neuromodulation, the team sends a concise summary of the rationale, planned protocol, and expectations to the patient’s primary physician, mental health providers, and therapists, inviting collaboration rather than parallel, disconnected care. During the course of treatment, brief progress updates can prevent conflicting messages—such as another clinician attributing all improvements solely to medication or, conversely, expressing skepticism about the legitimacy of neuromodulation. After completing a stimulation course, a structured handover outlines achieved gains, ongoing vulnerabilities, and recommended follow-up, including booster sessions if evidence supports them, or alternative pathways if neuromodulation was not beneficial.

Addressing practical barriers such as cost, insurance coverage, and travel is also part of implementation. Many insurers restrict coverage for TMS to major depressive disorder and may not recognize FND as an approved indication, requiring detailed documentation emphasizing comorbid depression or anxiety when relevant, and referencing available evidence and research where policies allow clinical discretion. When coverage is limited or absent, clinicians must discuss out-of-pocket costs transparently and help patients weigh these against uncertain benefits. For those living far from specialized centers, clustering multiple sessions within fewer weeks or using hybrid models that combine in-person neuromodulation with local physiotherapy or telehealth psychotherapy can help reduce travel burden.

Training and supervision of staff are important for maintaining quality and consistency. Operators of TMS, tDCS, or vagus nerve stimulation devices require not only technical competence but also familiarity with FND-specific communication strategies. Regular case-based supervision allows discussion of challenging scenarios, such as patients who become highly distressed during stimulation, those who attribute every life event to the device, or those whose symptoms worsen significantly despite protocol adherence. Peer review of session notes, periodic recalibration of devices, and adherence to safety guidelines from professional societies help ensure that neuromodulation is delivered reliably and ethically.

Documentation practices should capture both the technical and experiential aspects of treatment. For each session, clinicians record stimulation parameters, concurrent therapies delivered the same day, acute side effects, patient-reported changes, and any notable behavioral or emotional reactions. Over time, this detailed record can reveal patterns—such as better response when stimulation is followed by intensive motor practice, or increased anxiety with specific parameter changes—that inform real-time adjustments. Aggregated data across patients can support internal quality improvement initiatives and, when appropriately anonymized, contribute to broader practice-based evidence that complements formal clinical trials.

Managing the end of a neuromodulation course requires as much care as initiating it. As the planned sessions draw to a close, clinicians review the initial goals, compare them with outcomes, and explicitly name gains, even when partial. They also acknowledge any unachieved aims and explore contributing factors without framing the experience as a failure. A concrete maintenance plan is agreed upon, emphasizing continued physiotherapy or occupational therapy exercises, ongoing psychotherapy when indicated, and strategies for early intervention if symptoms flare. For some, a tapering schedule of less frequent neuromodulation sessions may be considered, while for others, a clear endpoint with focus on self-management is preferable.

Incorporating patient feedback into service design helps refine how neuromodulation is implemented. Structured satisfaction surveys, open-ended interviews, or patient advisory groups can highlight practical issues—such as clinic hours, transportation challenges, or the emotional impact of waiting areas and procedural rooms—that may affect engagement and perceived benefit. Listening to these perspectives supports iterative adjustments in workflows, physical space, and communication practices, making neuromodulation not simply a technical procedure but an integrated component of compassionate, person-centered FND care.