Efficacy of Hypnosis and Catalepsy Induction in Functional Neurological Disorders

ABSTRACT

Background

Patients with Functional Neurological Disorder (FND) experience complex patterns of motor and/or sensory symptoms. Treatment studies of psychological interventions are promising but limited.

Objectives

The aim of the current pilot study is to investigate the effect of treatment consisting of a combination of hypnosis and catalepsy induction on FND symptom severity.

Methods

A within‐subject waiting list‐control design was used with 46 patients diagnosed with FND. The treatment consisted of 10 sessions. The primary outcome measure was FND symptom severity (The Psychogenic Movement Disorder Rating Scale; PMDRS). The secondary outcome measures were psychological distress and quality of life.

Results

The repeated measures (RM) ANOVA for the PMDRS as outcome measure revealed a significant effect for time with a large effect size (η ² = 0.679). Pairwise comparisons indicated that the effect of time in the treatment period was significant for the measure of FND symptom severity, whereas the waiting list period was not. The effect remained stable even at 8 weeks post treatment. As for the additional measurement, general psychological distress and quality of life, no statistically significant differences between individual time points were found.

Conclusions

This pilot study showed that eight sessions of treatment consisting of a combination of hypnosis and catalepsy induction was effective in reducing FND symptom severity. Some explanations and limitations are provided in the paper as well as several avenues of future research.

Functional neurological disorder (FND) is a disorder describing motor and sensory symptoms that are experienced and related to a functional rather than a structural disorder. In the DSM‐5 seven FND symptom types are specified: weakness or paralysis, abnormal movement, swallowing symptoms, speech symptoms, attacks or seizures, anesthesia or sensory loss and special sensory symptoms. ¹ Since this version of the DSM the FND diagnosis can now be made without the presence of a psychological stressor. ² Research suggests that roughly 16% of all new patients at neurological outpatient clinics meet the requirements of an FND diagnosis. ³ Population‐based studies point towards an incidence rate of 4 to 12 per 100,000 per year for functional neurological symptoms. ⁴ FND seems to be one of the most frequently encountered diagnoses in neurological practice. ⁵ , ⁶ Moreover, it can be accurately diagnosed by neurologists. ² The relative high incidence rate and accurate assessment makes it somewhat surprising that high quality studies on how to treat FND are relatively scarce. ⁷

During the last few years several intervention studies have been published on the treatment of FND. As of yet without any definite conclusions. ⁸ There is tentative evidence to support the use of cognitive behavioral therapy (CBT) and physiotherapy. ⁷ The treatment of FND with CBT in general focuses on reducing symptoms by challenging maladaptive beliefs and reversing avoidance and other unhelpful illness behaviors. ⁹ Hoogduin et al developed a treatment for FND with both hypnosis and catalepsy induction focusing on teaching an incompatible response that does not correspond to the movement disorder. ¹⁰ The protocol focuses on both motor and sensory symptoms within FND. Within this protocol the focus is on applying behavioral therapeutic interventions.

Hypnosis has been used for treating FND since the previous century with numerous reported case studies and varying results. In 2002 Moene et al examined the effects of hypnosis in a comprehensive clinical treatment program for in‐patients with a persistent conversion disorder of the motor type. ¹¹ They found that the use of hypnosis had no additional effect on treatment outcome. But in 2003 Moene et al conducted a controlled study on 44 inpatients to study the effect of a hypnosis‐based interventions on FND symptoms. ¹² The authors concluded that, for motor type FND, the results of their study support the assumption that a hypnosis based treatment might well be an effective treatment.

Suggestion in hypnosis has been applied to the treatment of FND. ¹³ FND is characterized by heightened responsiveness to verbal suggestion. ¹⁴ Suggestion refers to an intentional communication of beliefs or ideas, whether verbally or nonverbally, to produce subjectively convincing changes in experience and behavior. The suggestions used in the protocol of Hoogduin et al, ¹⁰ are only symptom‐focused (designed to resolve a symptom).

Catalepsy was added to this treatment to further train FND patients to have a renewed/increased control over their motor function. Induced catalepsy has the effect of impairing the ordinary perception and motor functioning of the cataleptic body part. ¹⁵ Which in FND patients can cause a tremor to stop trembling or a person with a gait disorder to learn to walk again. Utilizing catalepsy induction teaches the patient to achieve a technique of firmness in the muscles. During treatment the patient learns to induce this feeling of firmness. As the patient uses the catalepsy induction more and more often a form of automatism will develop. ¹⁶ To summarize, literature on behavioral therapy consisting of a treatment with hypnosis is promising but scarce. In fact literature on behavioral therapy consisting of a combined hypnosis and catalepsy treatment is very rare and only a few case reports are available.

The aim of the current study is to investigate whether behavioral treatment, consisting of a combination of hypnosis and catalepsy induction, leads to a reduction of FND motor symptom severity using the Psychogenic Movement Disorder Rating Scale (PMDRS). ¹⁷ In addition, as secondary measures, we will assess the effect of the treatment on general psychopathology and quality of life. Patients diagnosed with FND were treated with behavioral therapy in accordance with the treatment protocol of Hoogduin et al. ¹⁰ Following the intake patients were placed on a waiting list which lasted 8 weeks until treatment start. A within‐subject design waiting list‐control design was utilized, in which patients that undergo treatment act as their own control group during the waiting list period. We hypothesized that this treatment would lead to a greater reduction of symptoms than the control condition. In addition we expected the treatment to have a positive effect on our secondary measures.

Methods

Participants

Patient data was collected at the HSK Center of Expertise for Functional Movement Disorders, a Dutch healthcare institution specialized in treating patients with FND. Various neurologists from Dutch hospitals referred the patients. Inclusion criteria were: 18 years of age or older and functional motor symptom diagnosed by a neurologist. The diagnosis was confirmed with the short version of the Schedules for Clinical Assessment in Neuropsychiatry (mini‐SCAN). ¹⁸ Exclusion criteria were insufficient command of the Dutch language, suicidal tendencies, comorbidity with a psychotic disorder, substance use disorder and/or a severe depression at the time of the intake. Between October 2018 and December 2019 in total 64 participants were included in the initial study sample. However, 18 of them had to be excluded from the analysis because they did not show up for treatment (n = 1), dropped out of treatment due to medical reasons (n = 2), participants withdrew from the study after five sessions (n = 5), participants withdrew from the study after seven sessions (n = 2), no data was available for one or more questionnaires (n = 7) and their symptoms were found not to be functional (n = 1). This resulted in a total final sample size of 46 participants, consisting of 35 females and 11 males. Participants’ age ranged from 18 to 79 years (M = 43.87, SD = 15.48). However additional participants were excluded from analysis of each individual questionnaire if they failed to report at two or more time points. This was the case for one participant on the PMDRS and three for the WHOQoL‐BREF. This resulted in sample sizes of 45 and 43 subjects, respectively. All 46 participants did complete the SQ‐48 at all measurement times.

Measures

The primary outcome measure was FND severity measured by the Psychogenic Movement Disorder Rating Scale (PMDRS). ¹⁷ The PMDRS was assessed by the therapists. The PMDRS consists of two subsections. The first section rates “phenomena” (rest tremors, action tremors, dystonia, chorea, bradykinesia, myoclonus, tics, athetosis, ballism and cerebellar incoordination) as either present or absent. The second section assesses “functions” (speech, walking and writing). In both parts the severity, duration and global capacity loss are measured on a five‐point scale. The total score is obtained by summing up the scores of the first and second section. The psychometric characteristics of the rating scale are satisfactory. ¹⁷ The interrater reliability for the presence or absence of each phenomenon is good (Kappa range 0.63–0.86). The Spearman correlation coefficient between assessors ranged from 0.86 to 0.90. Although for the measurement of FND it is primarily to measure only a part of FND ¹⁹ namely its motor symptoms.

The secondary outcome measures were psychological distress and quality of life measured by the SQ‐48 ²⁰ and World Health Organization Quality of Life‐BREF ²¹ (Cronbach's alpha between 0.66 and 0.84 for the different subscales), respectively. The SQ‐48 measures general psychopathology (anxiety, depression, somatic symptoms, social phobia, agoraphobia, aggression and cognitive symptoms) as well as the level of functioning (work/study and vitality) of the patient over the last week. The SQ‐48 has adequate psychometric qualities (Cronbach's alpha between 0.78 and 0.98 across the different subscales). ²¹ , ²⁵ The WHOQoL‐BREF ²¹ was used to measure quality of life. This measurement has adequate psychometric characteristics (Cronbach's alpha between 0.66 and 0.84 across the different subscales), in the Dutch version, with the exception of the social relations domain. ²³

Next to these measurements as a secondary measurement we also asked some questions about how the participant experiences their symptoms. But due to unreliability and unknown validity we removed these from the final article. These questions as well as the result on these items can be requested from the authors.

Treatment

All patients received an outpatient treatment. The treatment followed Hoogduin et al's FND protocol, which is designed specifically to reduce FND symptoms. ¹⁰ Therapists were behavioral therapist or behavioral therapists in training. They were experienced in the treatment for FND based on the protocol from Hoogduin et al. ¹⁰ In the protocol all essential elements of treatment are clearly defined and all therapists knew exactly how to perform the same treatment. This treatment consists of sessions of 1.5 h each. During treatment, the quality of treatment delivery by the clinicians was done through supervision, training and peer learning. These activities were aligned with the concept of deliberate practice. ²⁴ , ²⁵ Deliberate practice aims not only to enhance treatment adherence but to improve technical and interpersonal skills in order to optimize treatment outcomes.

Upon the first therapy session following the intake, hypnotic principles were explained to the patients. Moreover an introductory hypnosis exercise was performed to introduce patients to the hypnotic trance. During the hypnotic state, the first goal of the therapy is to diminish the symptoms during the hypnotic state. This is achieved by evoking an incompatible response. An incompatible response is a sensation in the subject's body that does not correspond to the FND symptom. For example: an incompatible response for involuntary movements would be a sensation of heaviness, which the therapist achieves by giving suggestion of weight increasing on the limbs. After intensive training with hypnosis, a form of conditioning is created and the patient will be able to induce that incompatible feeling even without hypnosis (cue‐conditioning). ¹⁶ During the second and third sessions, an incompatible response specific to the patient's symptoms was taught and induced in hypnotic trance. In the fourth session patients learned to evoke the incompatible response without any formal induction.

Following the sessions with hypnosis, 4 weekly sessions using catalepsy‐induction were performed. Catalepsy is a state of tonic immobility, a freeze type response on anxiety. However this sensation can also be intentionally induced and can produce stiff, heavy and abnormal feelings in the limbs. ¹⁵ This technique was only used originally to help patients get into a hypnotic state. ²⁶ However due to its ability to directly influence subjective experiences, Hoogduin argues that catalepsy induction by itself is applicable in FND treatment. ²⁷ For instance the technique could be utilized to control involuntary movements and gait disorders by means of stiffening of the limbs.

During the first catalepsy‐oriented therapy session the mechanism behind catalepsy was explained. Thereafter patients were trained to make their own arms cataleptic. In the following three sessions the exercises were focused on patient‐specific symptoms and were individualized. For instance patients with tremors, were taught to make their arms cataleptic; to stop the shaking movement patterns. On the other hand, patients suffering from walking problems were taught to make their own legs cataleptic and were trained to walk with cataleptic legs.

Apart from the exercises, which were performed during the therapy sessions, patients were instructed to practice hypnosis and catalepsy 5 to 10 times a day as homework. Furthermore 8 weeks after the last therapy session, the patients were invited for a follow‐up session to review the long‐term effectivity of the received therapy. In total the treatment course consists of 10 sessions: an intake, 8 therapy sessions and a follow‐up appointment.

Procedure

The patients were treated in an outpatient treatment facility in the Netherlands. A pre‐treatment assessment was conducted including a short version of the Schedules for Clinical Assessment in Neuropsychiatry (mini‐SCAN). ¹⁸

During the intake a baseline measurement was done to assess whether the patients fit the in‐ and exclusion criteria of the study. If they were eligible the patients were informed about the current study and asked if they wanted to participate. If they agreed they received a detailed description of the study procedures and were asked to provide written informed consent. Afterwards they were placed on a waiting list, which lasted an average of 8 weeks until treatment started. In the meantime patients were asked not to undergo any other treatments, such as physical therapy.

The therapy course consisted of 4 sessions during 4 weeks with hypnosis‐based treatment, and thereafter 4 sessions during 4 weeks with catalepsy‐based treatment. These 8 weekly sessions were followed by 8 weeks without treatment until the follow‐up session. See Figure 1 to outline the timeline.

Figure 1.

Flowchart research project.

The PMDRS and SQ‐48 were measured at five points in time during treatment: a baseline measurement at the intake (T0), at the start of treatment (T1), halfway of the treatment (T2; after session 5), at the end of treatment (T3) and at follow‐up (T4). The WHOQoL‐BREF was measured at four points during treatment: at the intake (T0), at the start of treatment (T1), at the end of treatment (T3) and at follow‐up (T4).

This study was carried out under the general ethical guidelines of the healthcare institution the data was collected at. No additional external ethical approval was necessary as the provided treatment was the standard treatment and patient investment was minimal. Patients gave informed consent at the intake that their data could be used for research purposes. The data was processed anonymously.

Study Design

A within‐subject waiting list‐control design was used. In this way the patients that undergo treatment act as their own control group during the waiting list period.

Data Analysis

The data was analyzed using the Statistical Package for the Social Sciences (SPSS), version 26. The data was checked for missing values before further analysis. Mean substitution was used for the missing data. To determine whether the severity of FND symptoms (PMDRS), general psychological distress (SQ‐48) decreased and quality of life (WHOQoL‐BREF) increased, three Repeated Measures (RM) ANOVAs were conducted, with time as the within‐subject factor and the individual outcome measures as the dependent variables. To control for probability in multiple comparisons between time points, Bonferroni adjusted pairwise comparisons were used between time points.

Results

First missing values were determined. Mean substitution was used for the remaining missing values consisted of one total missing time point for the PMDRS, three total missing values for the SQ‐48 and 10 total missing values for WHOQoL‐BREF. Mean scores and standard deviations over the different measures and timepoint are reported in Table 1.

TABLE 1.

Mean and Standard Deviations over time over treatment course (N = 46)

Measure	M (SD)
	T0	T1	T2	T3	T4
PMDRS	18.36 (11.03)	18.40 (11.46)	11.97 (8.61)	8.92 (7.23)	7.02 (7.6)
SQ‐48	48.71 (24.91)	47.69 (26.93)	42.81 (26.61)	40.13 (28.40)	37.73 (28.99)
WHOQoL‐BREF	82.77 (11.71)	81.07 (15.10)		87.31 (14.78)	89.49 (15.21)
Physical health	17.82 (3.63)	18.05 (5.10)		21.47 (5.08)	21.48 (5.59)
Psychological health	19.65 (3.30)	18.59 (4.42)		20.12 (4.07)	20.70 (4.32)
Social	10.76 (2.69)	10.39 (2.62)		10.63 (2.43)	10.92 (2.43)
Environment	28.52 (4.83)	28.52 (5.20)		30.24 (5.32)	30.21 (5.44)

In regard to FND symptoms the repeated measures (RM) ANOVA for the PMDRS (primary measurement) as outcome measure revealed a significant effect for time with a large effect size, F _(4,41) = 21.69 P < 0.001, partial η ² = 0.679. Bonferroni adjusted pairwise comparisons (Table 2) indicated that the effect of time in the treatment period was significant (T1–T3) for the outcome measure, whereas the waiting list period (T0–T1) was not. This means that patients’ FND symptoms did not change whilst being placed on a waiting list, but did improve significantly as a result of the intervention. Moreover, the differences between end treatment measure and follow‐up measure were not significant (T3–T4), which indicates the therapy outcome did not change after an 8‐week post‐treatment follow‐up, but that the effect was stable. As to general psychological distress, the RM ANOVA for the SQ‐48 indicated that the effect of time was not significant, F _(4,42) = 2.3, P = 0.075, partial η ² = 0.18. There are no significant differences between individual time points (Table 2). This suggests that patients’ distress reduction did not reach statistical significance as a result of the intervention. Regarding quality of life the RM ANOVA for the WHOQoL‐BREF identifies significant differences over the therapy course F _(3,40) = 8.22, P < 0.001, partial η ² = 0.38. However upon closer inspection of Bonferroni‐adjusted comparisons (Table 2) we can establish that this significance is mainly driven by the fact that the WHOQoL‐BREF outcome (non‐significantly) decreased during the waiting list period and later increased during the treatment period. Although this increase is significant for the treatment period, the increase between T0 and T3 is not significant. This indicates that quality of life of participants somewhat decreased during anticipation of therapy and increased back to the level prior to commencement of the study. Inspection of mean scores of the subscales (Table 1) suggests this might be true for all individual domains of life.

TABLE 2.

Change across multiple time points using pairwise Bonferroni‐adjusted comparisons

Measure	Treatment				Follow‐up
PMDRS	T0 = T1	T1 > T2***	T2 > T3***	T0 > T3 ***	T3 = T4
SQ‐48					T3 = T4
WHOQoL‐BREF	T0 = T1 T0 = T1	T1 = T2 T1 > T3*	T2 = T3	T0 = T3 T0 = T3	T3 = T4

Note: p < 0.0001 (in bold).

= indicates non significance, > indicates significant change.

^* P ≤ 0.05.

^*** P ≤ 0.001.

In order to check if the used mean imputation did not lead to an under or over estimation of the found effects all analysis were also conducted without the utilization of mean imputation. The effects were found to be similar (PMDRS F _(4,40) = 20.94 P < 0.001, partial η ² = 0.677; SQ‐48 F _(4,39) = 2.89, P = 0.036, partial η ² = 0.23; WHOQoL‐BREF F _(3,32) = 6.79, P = 0.001, partial η ²  = 0.389). Thus leading to the conclusion that the used imputation did not lead to a bias with the exception of the SQ‐48, which found a significant effect of time. This indicates a potential underestimation by the mean imputation of the effect on this secondary measurement.

Discussion

This pilot study showed that behavioral therapy with hypnosis and catalepsy led to a greater decrease of symptom severity in FND patients than a waiting list period. To be more specific, patients’ FND symptoms did not change whilst being placed on a waiting list, but did improve significantly as a result of the intervention. These results stayed stable at 8‐week post‐treatment. Moreover the attained effect size, regarding FND symptoms, was large (partial η ² = 0.679). These results indicate that treatment with hypnosis and catalepsy has a significant effect on clinician rated measurement (PMDRS). The findings of a decrease in FND symptoms due to the behavioral treatment were consistent with the findings of Moene et al. ¹² This seems to indicate that the motor symptoms of FND can be successfully treated with behavioral therapy. As this was a pilot study further controlled studies need to be done to corroborate these promising findings.

As mentioned before, there is some evidence to support the use of physiotherapy and now somewhat more evidence to support the use of behavioral therapy in the treatment of FND. But if we look closely at these two treatments they do not differ as much. One could argue that behavioral therapy consisting of hypnosis and catalepsy induction is a combination of CBT and physical therapy without the element of challenging dysfunctional cognitions.

Contrary to the results for FND symptoms, a significant effect for improvement on psychological distress and quality of life has not been found. Of course this might mean that behavioral therapy might have no effect on said factors. This seems to be unlikely when one looks at the debilitating symptoms of FND. A possible explanation could be that the WHOQoL‐BREF and SQ48 have little sensitivity for change in FND patients. Meaning that these instruments are unable to measure the change in FND patients. This also applies to our primary measure. Another possibility is that the motor symptoms of FND are not the root cause of psychological stress and quality of life. Fatigue often explains more disability and distress. Gelauff and colleagues found that fatigue is a prevalent problem in motor FND. ²⁸ It significantly affected quality of life and self‐rated health.

In this study, we used the PMDRS, but this assessment tool deals only with the motor symptoms of FND. To date, a handful measuring instruments applicable to FND exist, ¹⁹ but no measure covering its whole spectrum of symptom types. Similarly no questionnaire has been developed specifically to assess quality of life for FND patients. Thus underlining the real need for more studies in FND on both the way in which to successfully treat this affliction and how to reliably measure progress both in clinical practice and research.

Strengths of this pilot study are the use of a waiting list control condition and the utilization of a strict protocol for all involved therapists which limits therapist variation. Our final sample size consisted of 46 participants; which is an adequate size for a pilot study. Nevertheless, limitations should be considered. One limitation of this study is the fact that all patients have received hypnosis and catalepsy without controlling for order‐effects. Therefore we do not know if one of the techniques is a stronger drive for reduction of the FND symptoms than the other—or if the combination of treatments is most responsible for the revealed effects. Further research should investigate this. Another limitation is that the used waiting list control condition, although suited for a pilot study, does not give complete certainty that the attained results are due to the therapy. In future studies into this specific treatment, a more controlled design should be used.

A shortcoming of the study is that of the 64 participants eligible for the study, a total of 18 dropped out or were lost to follow‐up. It is unknown whether their data would have changed the results. Unfortunately, there were missing values. It is possible that the mean imputation may have skewed the treatment effect size. In addition, after 8 weeks there was a follow‐up and the results stayed stable. But we do not know what happens after this period. In future studies we would ideally schedule a follow‐up after 6 months and 1 year.

Although interest in research on FND has increased dramatically in recent years, research on effective interventions remains very limited. ²⁹ Therefore the findings of this pilot study are of clinical relevance and add to the growing amount of literature on FND. Future research requires studies in a larger cohort, preferably in a more controlled design with a better control condition.

With this study, a vital step has been taken in demonstrating the efficacy of behavioral therapy using hypnosis and catalepsy induction in the treatment of patients with FND. Moreover, this study shows that a short‐term symptom‐focused approach to FND treatment with eight sessions is effective and stays effective 8 weeks post‐treatment.

Author Roles

(1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the first draft, B. Review and Critique.

M.I.T.: 1A, 1B, 1C, 3A.

A.v.O.: 2A, 2C, 3B.

J.S.: 2B, 3A.

W.B.: 2A, 2B.

M.A.T.: 2C, 3B.

M.M.: 1A, 2A, 2C, 3B.

Disclosures

Ethical Compliance Statement: The authors confirm that this study was approved by an internal review board, and that the approval of an institutional review board was not required for this study. The patients were informed about the current study and asked if they wanted to participate. If they agreed, they received a detailed description of the study procedures and were asked to provide written informed consent. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Funding Sources and Conflict of Interest: This research did not receive any specific grant from funding agencies in the public, commercial, or not‐for‐profit sectors. The study was conducted at the HSK Expertise Center Functional Movement Disorders. This can be seen as a conflict of interest.

Financial Disclosures for the Previous 12 Months: This research did not receive any specific grant for the previous 12 months.