[Functional neurological disorders: A clinical anthology]

Functional neurological disorders have a broad phenotypic spectrum and include different clinical syndromes, which are sometimes associated to each other or appear consecutively over the course of the disease. This clinical anthology provides details on the specific and sensitive positive signs that are to be sought in the context of a suspected functional neurological disorder. Beside these positive elements leading to the diagnosis of functional neurological disorder, we should keep in mind the possibility of an associated organic disorder as the combination of both organic and functional disorders is a relatively frequent situation in clinical practice. Here we describe the clinical characteristics of different functional neurological syndromes: motor deficits, abnormal hyperkinetic and hypokinetic movements, voice or speech disorders, sensory disorders, and functional dissociative seizures. The clinical examination and the identification of positive signs play a critical role in the diagnosis of functional neurological disorder. Knowledge of the specific signs associated with each phenotype render possible to make an early diagnosis. For that matter, it contributes to the improvement of patient care management. It allows to a better engagement in an appropriate care pathway, which influence their prognosis. Highlighting and discussing positive signs with patients can also be an interesting step in the process of explaining the disease and its management.

Symptom-severity-related brain connectivity alterations in functional movement disorders

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Brain connectivity alterations were found in functional movement disorders.

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Hyperconnectivity in temporoparietal junction and precuneus in functional weakness.

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Consistent brain connectivity differences with four different centrality measures.

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Motor symptom severity correlates positively with connectivity in functional weakness.

Background

Functional movement disorders, a common cause of neurological disabilities, can occur with heterogeneous motor manifestations including functional weakness. However, the underlying mechanisms related to brain function and connectivity are unknown.

Objective

To identify brain connectivity alterations related to functional weakness we assessed network centrality changes in a group of patients with heterogeneous motor manifestations using task-free functional MRI in combination with different network centrality approaches.

Methods

Task-free functional MRI was performed in 48 patients with heterogeneous motor manifestations including 28 patients showing functional weakness and 65 age- and sex-matched healthy controls. Functional connectivity differences were assessed using different network centrality approaches, i.e. global correlation, eigenvector centrality, and intrinsic connectivity. Motor symptom severity was assessed using The Simplified Functional Movement Disorders Rating Scale and correlated with network centrality.

Results

Comparing patients with and without functional weakness showed significant network centrality differences in the left temporoparietal junction and precuneus. Patients with functional weakness showed increased centrality in the same anatomical regions when comparing functional weakness with healthy controls. Moreover, in the same regions, patients with functional weakness showed a positive correlation between motor symptom severity and network centrality. This correlation was shown to be specific to functional weakness with an interaction analysis, confirming a significant difference between patients with and without functional weakness.

Conclusions

We identified the temporoparietal junction and precuneus as key regions involved in brain connectivity alterations related to functional weakness. We propose that both regions may be promising targets for phenotype-specific non-invasive brain stimulation.

Diagnosis of Functional Weakness and Functional Gait Disorders in Children and Adolescents

Functional neurological disorder is neurological dysfunction not primarily explained by pathophysiologic or structural abnormalities and can present in children and adolescents with limb weakness, gait abnormality, non-epileptic seizures or sensory changes. In this review article we focus primarily on the diagnosis of functional limb weakness and functional gait disorders, and how to differentiate functional neurological disorders from structural or pathologic neurological presentations of weakness or gait disturbance. Detailed history and attentive observation of a patient outside of the formal neurological examination can be pertinent to identifying inconsistency and incongruency in keeping with functional neurological presentations. Understanding of structural and physiologic neurological pathology is required to identify non-anatomical and non-pathological features consistent with a diagnosis of functional neurological disorder. Diagnosis is made on recognition of positive clinical features of a functional disorder on examination and is not based primarily on exclusion of a pathologic neurological disorder. Specific tests can be performed to elicit pathognomonic findings supportive of a diagnosis of functional limb weakness and gait disorders.

Adaptive Force and emotionally related imaginations - preliminary results suggest a reduction of the maximal holding capacity as reaction to disgusting food imagination

The link between emotions and motor control has been discussed for years. The measurement of the Adaptive Force (AF) provides the possibility to get insights into the adaptive control of the neuromuscular system in reaction to external forces. It was hypothesized that the holding isometric AF is especially vulnerable to disturbing inputs. Here, the behavior of the AF under the influence of positive (tasty) vs. negative (disgusting) food imaginations was investigated. The AF was examined in n = 12 cases using an objectified manual muscle test of the hip flexors, elbow flexors or pectoralis major muscle, performed by one of two experienced testers while the participants imagined their most tasty or most disgusting food. The reaction force and the limb position were measured by a handheld device. While the slope of force rises and the maximal AF did not differ significantly between tasty and disgusting imaginations (p > 0.05), the maximal isometric AF was significantly lower and the AF at the onset of oscillations was significantly higher under disgusting vs. tasty imaginations (both p = 0.001). A proper length tension control of muscles seems to be a crucial functional parameter of the neuromuscular system which can be impaired instantaneously by emotionally related negative imaginations. This might be a potential approach to evaluate somatic reactions to emotions.

Functional motor phenotypes: to lump or to split?

INTRODUCTION

Functional motor disorders (FMDs) are usually categorized according to the predominant phenomenology; however, it is unclear whether this phenotypic classification mirrors the underlying pathophysiologic mechanisms.

OBJECTIVE

To compare the characteristics of patients with different FMDs phenotypes and without co-morbid neurological disorders, aiming to answer the question of whether they represent different expressions of the same disorder or reflect distinct entities.

METHODS

Consecutive outpatients with a clinically definite diagnosis of FMDs were included in the Italian registry of functional motor disorders (IRFMD), a multicenter data collection platform gathering several clinical and demographic variables. To the aim of the current work, data of patients with isolated FMDs were extracted.

RESULTS

A total of 176 patients were included: 58 with weakness, 40 with tremor, 38 with dystonia, 23 with jerks/facial FMDs, and 17 with gait disorders. Patients with tremor and gait disorders were older than the others. Patients with functional weakness had more commonly an acute onset (87.9%) than patients with tremor and gait disorders, a shorter time lag from symptoms onset and FMDs diagnosis (2.9 ± 3.5 years) than patients with dystonia, and had more frequently associated functional sensory symptoms (51.7%) than patients with tremor, dystonia and gait disorders. Patients with dystonia complained more often of associated pain (47.4%) than patients with tremor. No other differences were noted between groups in terms of other variables including associated functional neurological symptoms, psychiatric comorbidities, and predisposing or precipitating factors.

CONCLUSIONS

Our data support the evidence of a large overlap between FMD phenotypes.

Paradoxical wrist flexion: A new test to detect functional weakness of the upper limb

Background

Positive signs are essential for the diagnosis of functional neurological disorders (FND). The author described a new positive sign to diagnose functional weakness (FW), "paradoxical wrist flexion", and tested its validity.

Methods

The test comprised Medical Research Council (MRC) examinations of wrist flexion in two different limb positions, one with the wrist maximally flexed (wrist flexion in the flexed position; WFfl) and the other with the wrist in the neutral position (wrist flexion in the extended position; WFex). In "organic" weakness (OW), WFfl should be stronger than WFex according to the dynamic theory. Paradoxical wrist flexion was judged positive when the MRC score for WFfl was lower than that for WFex. A higher MRC score for WFfl than WFex was considered an "organic sign" for wrist flexion. We retrospectively enrolled patients with FND or other "organic" neurological disorders, who presented with wrist flexor weakness with an MRC score of 4.

Results

Twenty-four patients with FW and 40 patients with OW were enrolled. Paradoxical wrist flexion was positive in 16 patients with FW and in no patients with OW, i.e. 67% sensitivity and 100% specificity. The "organic sign" for wrist flexion was positive in no patients with FW and in 35 patients with OW, i.e. 88% sensitivity and 100% specificity.

Conclusions

Paradoxical wrist flexion is useful for the detection of nonorganic paresis. The background theory is that an active movement is more severely affected in FW than a passive movement when maintaining a limb position.

Chasing the Chameleon: Psychogenic Paraparesis Responding to Non-Invasive Brain Stimulation

Neurologic symptoms that develop unconsciously and are incompatible with known pathophysiologic mechanisms or anatomic pathways belong to Conversion Disorder (CD). CD diagnosis is based on the clinical history and the exclusion of physical disorders causing significant distress or social and occupational impairment. In a subgroup of CD, called functional weakness (FW), symptoms affecting limbs may be persistent, thus causing a permanent or transient loss of limb function. Physiotherapy, pharmacotherapy, hypnotherapy and repetitive transcranial magnetic stimulation (rTMS) have been proposed as treatment strategies for FW-CD. Herein, we report a 30 year-old male, presenting with lower limb functional paraparesis, having obtained positive, objectively, and stable effects from a prolonged r-TMS protocol associated to a multidisciplinary approach, including psychological and sexuological counseling, and monitored by gait analysis. We postulate that our rTMS protocol, combined with a multidisciplinary approach may be the proper treatment strategy to improve FW-CD.

Differences in illness perceptions between patients with non-epileptic seizures and functional limb weakness

OBJECTIVES

Illness perceptions play an important role in the onset and maintenance of symptoms in functional neurological symptom disorder (conversion disorder). There has, however, been little work examining differences between subtypes of this disorder. We therefore aimed to compare illness perceptions of patients with non-epileptic seizures (NES) and those with functional weakness (FW) with matching neurological disease controls to examine their specificity.

METHODS

The Illness Perception Questionnaire Revised (IPQ-R) was completed by patients with functional limb weakness, non-epileptic seizures and patients with neurological disease causing limb weakness and epilepsy in two separate case control studies.

RESULTS

Patients with FW (n=107), NES (=40), Epilepsy (n=34) and neurological disease causing limb weakness (NDLW) (n=46) were included in the analysis. Both FW and NES patients reported a low level of personal control, understanding of their symptoms and a tendency to reject a psychological causation of their symptoms. However NES patients rejected psychological causes less strongly than FW patients (P<.01). Patients with NES were also more likely to consider their treatment to be more effective (P<.01). None of these differences appeared in a similar comparison between patients with epilepsy and patients with NDLW.

CONCLUSION

Although patients with NES tended, as a group, to reject psychological factors as relevant to their symptoms, they did so less strongly than patients with functional limb weakness in these cohorts. This has implications for both the way in which these symptoms are grouped together but also the way in which treatment is approached.

Differences in relatives' and patients' illness perceptions in functional neurological symptom disorders compared with neurological diseases

OBJECTIVE

The illness perceptions of the relatives of patients with functional neurological symptom disorders (FNSDs) and their relation to the illness perceptions of the patients have been little studied. We aimed to compare illness perceptions of relatives of patients with FNSDs with those held by patients themselves. We used control pairs with neurological diseases (NDs) to examine the specificity of the findings to FNSDs.

MATERIAL AND METHODS

Patients with FNSDs (functional limb weakness and psychogenic nonepileptic seizures) and patients with NDs causing limb weakness and epilepsy, as well as their relatives, completed adapted versions of the Illness Perception Questionnaire - Revised (IPQ-R).

RESULTS

We included 112 pairs of patients with FNSDs and their relatives and 60 pairs of patients with NDs and their relatives. Relatives of patients with FNSDs were more likely to endorse psychological explanations and, in particular, stress as causal factors than patients with FNSDs (p<.001). Relatives of patients with FNSDs were also more pessimistic about the expected duration of the disorder and perceived a greater emotional impact compared with patients themselves (p<.001). However, the latter two differences between patients and relatives were also found in pairs of patients with NDs and their relatives.

CONCLUSION

The main difference in illness perceptions between relatives and patients that appeared specific to FNSDs was a tendency for relatives to see psychological factors as more relevant compared with patients. Some other differences were observed between pairs of patients with FNSDs and their relatives, but the same differences were also seen in pairs of patients with NDs and their relatives. These other differences were, therefore, not specific to FNSDs. Discussion about possibly relevant psychological factors with patients suffering from FNSDs may be helped by including relatives.

Large-field repetitive transcranial magnetic stimulation with circular coil in the treatment of functional neurological symptoms

OBJECTIVE

Patients with functional neurological symptoms (FNS) are frequently encountered by neurologists and are difficult to treat. Symptoms are multiple and may appear concurrently or successively in the same patient. To date, few studies have been published on focal repetitive transcranial magnetic stimulation (rTMS) in FNS. This type of stimulation induces a focal current, vertically in the cortex. Results are contradictory, probably because it is difficult to identify a limited cortical area that triggers these symptoms. We assessed the efficacy of another type of rTMS: large-field stimulation by means of a circular coil covering a surface area approximately 20 times greater and inducing a circular current tangentially to the cortex.

PUBLISHED STUDIES

We analysed two studies on the efficacy of large-field rTMS in functional paralysis and in functional movement disorders. The efficacy of large-field rTMS was very marked in these two studies.

PERSONAL NON-PUBLISHED STUDIES

We reported several open series, including patients with functional sensory loss, functional visual loss, and non-epileptic seizures.

METHOD

For all patients, one or several sessions of 60 stimuli with circular coil were carried out with a protocol depending on the symptoms.

RESULTS

The efficacy of large-field rTMS was dramatic in all patient series. Additionally, we discuss the possible involved mechanism: placebo effect, cognitive behavioural effect or neuromodulatory effect.

CONCLUSION

According to the data from these different studies, large-field rTMS could be a new therapy for patients with FNS. However, controlled studies are mandatory.