Functional neurological symptoms (FNS) are common and account for a significant proportion of new presentations to Neurology outpatients (as a single or co-morbid presentation) [1]. These symptoms manifest as behaviours seen in conditions of neurological disease or injury (such as dystonia, paralysis, movement disturbance, seizures), but without an identifiable organic pathogen or structural defect which could produce such symptoms. These conditions are also known as conversion or dissociative disorders in psychiatric diagnostic terms. ICD-11 now uses the diagnostic label ‘Dissociative Neurological Symptom Disorder’, although ‘Functional Neurological Disorder’ (FND) is currently the most commonly used term.

Increasingly, patients with FNS have presented to neurology with these neurological symptoms, which has eventually led to a paradigm shift in understanding FNS, with an emerging movement to understand these conditions as resulting from cognitive neuroscience principles of how the brain processes ‘data’, and what happens when these processes go wrong. This does not discount psychosocial processes, it just explains a psychobiological mechanism by which FNS can be created and maintained, which had been absent from psychopathological theories.

The concept of the ‘Bayesian Brain’ in FNS is a contemporary cognitive neuroscience model, which applies particularly well to motor/movement FNS [2]. The model proposes that the brain and mind develops patterns of activation based upon prior experiences, which in turn allow these systems to make accurate predictions about cause and effect. If these predictions are ‘fit for purpose’, they minimise systemic surprise (i.e. an unexpected result), which produces disequilibrium – the antithesis to a system’s ‘desire’ to maintain homeostasis. A well balanced system will have reasonably accurate predictive capabilities, based upon flexible ‘top-down’ models of ourselves and the world (i.e. ‘schemas’ or specific functioning neural networks), which can be finessed through ongoing experience, by validating against incoming, ‘bottom-up’ data (i.e. sensory feedback from the resulting experience). If the ‘bottom-up’ data supports the predictions of the ‘top-down’ model, it is strengthened. If the ‘bottom-up’ data is incongruent the model has to either adapt to incorporate the new information, or ‘ignore’ the incongruency to maintain homeostasis. What determines the likelihood of either action is unclear, although the likely explanation is the relative strength of the top-down or bottom-up signals. It is hypothesised that in FNS, there is a creation of an overly dominant top-down process involving an inaccurate model, which resists any incongruent bottom up feedback (to maintain homeostasis) and is therefore inflexible and unable to adapt (to functional recovery from injury, for example).

Traditionally, FNS has been treated psychologically with therapies based upon psychodynamic and cognitive behaviour therapy approaches3. The emergence of the Bayesian Brain model in FNS gives us a new direction for neuropsychologically informed interventions; psychological therapies attempting to directly influence neurocognitive processes – therapies such as hypnosis.

Hypnosis works with the same elements that are theorised to act as the catalysts to create and maintain FNS within the Bayesian Brain model; attention, beliefs and agency. Attention refers to the system’s ‘interest’ in what is happening – internal or external experiences. Excessive attention to ‘malfunctioning’ parts, or specific processes in the body, appear to isolate that element from normal integrated functioning (which might also be called a physical dissociation), and so creates and perpetuates a functional symptom. Inaccurate beliefs about capability of functioning can also serve to ‘feed’ the rogue representation by being complicit. Agency (and self-awareness) refers to the perception that we are engaged or involved with a process which is happening. In FNS, the affected individuals are disconnected from this sense of agency2. Both attention and agency are neural processes (i.e. have discrete neural networks), as well as cognitive (thought) processes. top-down process, hypnosis involves a voluntary top-down [4] domination of conscious perception, involving the modulation of key neural networks which govern attention, self-awareness [5] (including agency) and goal directed behaviours. Therefore, we have an intervention which works on the same principles as those which are seen to maintain FNS. Contemporary hypnosis research has demonstrated that functional symptoms can be created and removed under hypnosis, with changes evidenced on brain imaging [6]. Hypnosis has been shown to reliably attenuate automatic ‘top down’ processes, such as word reading impulses in The Stroop Effect7. In terms of attention, hypnotic trance is a state of highly developed focused attention (or absorption), which can be voluntarily moved around to focus (or de-focus) upon different stimuli [8,9] to ameliorate symptoms. Hypnosis can also modulate one’s sense of agency/self-awareness [8,9]. That is, under hypnosis, actions (mental, perceptual, physical) can be suggested and enacted by the individual, without a sense that the individual is volitional in the process (as occurs in motor/movement FNS). It has been found that both FNS patients and high hypnotisable patients have less (somatosensory) self-awareness on the Libet’s test [10], which asks participant to gauge their awareness of an intention to make a movement, before the movement is initiated (which can give rise to a sense of involuntary action).

Imagery and re-scripting techniques are standard CBT approaches to working with a variety of mental health issues, including phobias and trauma. These techniques help to modify a person’s maladaptive beliefs, which hinder adaptive functioning. The hypnotic state allows for a more intense imagery experience, through greater absorption/focused attention. Therefore, hypnosis can be a powerful mechanism to help an individual alter dysfunctional beliefs, by facilitating vivid therapeutic imagery [11]

Hypnosis for FNS has a long history, at least from the late 18th century with Jean-Martin Charcot, Sigmund Freud, Pierre Janet and others, treating ‘hysteria’. It appears to be an intervention of potential merit for FNS [3] and has some well described hypnotic strategies to target specific FNS presentations [12], including what might be considered ‘functional overlay’ in patients with brain injury1.With the emergence of the ‘Bayesian Brain’ FNS model, the potential benefit of hypnosis with these conditions becomes even more obvious, by highlighting that the therapeutic mechanisms of hypnosis involves those very same processes, which in FNS, cause the dysfunction. We can therefore use hypnosis to more directly ‘re-calibrate’ the dysfunctional FNS system to restore a more even ‘power balance’ between top-down and bottom-up processes, so that adaptive change can be made.

The British Society of Clinical and Academic Hypnosis (BSCAH) is a registered charity and has been in existence in various forms since the 1950’s. Members and trainers are health care professionals, (HCP’s). Their aim is to promote the safe use and research of medical hypnosis.


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Main Image Credit

Main image courtesy Unsplash User MK Hamilton