Abduction finger sign: a new sign to detect unilateral functional paralysis of the upper limb

Misdiagnosis of functional neurological symptom disorders in paediatrics: Narrative review and relevant case report

Functional neurological symptom disorders (FNSD) pose a common challenge in clinical practice, particularly in pediatric cases where the clinical phenotypes can be intricate and easily confused with structural disturbances. The frequent coexistence of FNSDs with other medical disorders often results in misdiagnosis. In this review, we highlight the distinctions between FNSD and various psychiatric and neurological conditions. Contrary to the misconception that FNSD is a diagnosis of exclusion, we underscore its nature as a diagnosis of inclusion, contingent upon recognizing specific clinical features. However, our focus is on a critical learning point illustrated by the case of a 14-year-old male initially diagnosed with FNSD, but subsequently found to have a rare primary monogenic movement disorder (paroxysmal kinesigenic dyskinesia, PKD). The crucial takeaway from this case is the importance of avoiding an FNSD diagnosis based solely on psychiatric comorbidity and suppressible symptoms. Instead, clinicians should diligently assess for specific features indicative of FNSD, which were absent in this case. This emphasizes the importance of making a diagnosis of inclusion. Extended follow-up and clinical-oriented genetic testing might help identify comorbidities, prevent misdiagnosis, and guide interventions in complex cases, which cannot be simply classified as "functional" solely because other conditions can be excluded.

[Conclusion instead of exclusion-The clinical diagnosis of functional movement disorders]

Functional neurological movement disorders are common in neurological practice and lead to a high degree of impairment and chronification. Affected patients usually receive a diagnosis with considerable delay and often do not get disease-specific treatment. The reasons for this delay are related to extensive diagnostic measures to exclude other nonfunctional neurological diseases. As a consequence, functional movement disorders are typically communicated as diagnoses of exclusion, which makes it difficult for patients to understand and accept the diagnosis. This is particularly unfortunate, because in the majority of patients the diagnosis can be made with confidence based on clinical features, i.e., inconsistency and incongruence. The clarification of the symptoms and the resulting treatment options should be supplemented by patient-friendly explanations of the pathophysiological basis of the disease. In this way, patients are enabled to understand and accept the diagnosis. Moreover, it can put an end to the search for a diagnosis, which can sometimes take decades, and paves the way for treatment. Thus, the diagnosis by exclusion itself becomes the starting point for treatment and can itself have a therapeutic effect.

Forensic assessment of somatoform and functional neurological disorders

Functional neurological disorders (FND) and somatization are common in clinical practice and medicolegal settings. These conditions are frequently disabling and, if arising following an accident, may lead to claims for legal compensation or occupational disability (such as social security disability insurance). However, distinguishing FND and somatization from symptoms that are intentionally produced (i.e., malingered or factitious) may pose a major forensic psychiatric challenge. In this article, we describe how somatoform disorders and FND lie along a spectrum of abnormal illness-related behaviors, including factitious disorder, compensation neurosis, and malingering. We provide a systematic approach to the forensic assessment of FND and conclude by describing common litigation scenarios in which FND may be at issue. Forensic testimony may play an important role in the resolution of such cases.

[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.

[Borderline regions between neurology and psychiatry, focusing particularly on the functional neurological disorders]

Neurology in Japan did not develop from the separation of neuropsychiatry into neurology and psychiatry, which casts a shadow on the present situation of Japanese neurology. Functional neurological disorder (FND; hysteria) is a typical link between neurology and psychiatry. FND is a common disorder, which has been described from the ancient times and has also been the headstream of neurology. FND is not diagnosed by exclusion or by psychiatric causes, but should be actively diagnosed based on the neurological signs themselves (= positive signs of FND) as early as possible, with minimal ancillary tests. This opinion has been supported by the newest Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5). Many positive signs have been described. Assessment by a neurologist also becomes a treatment.

Diagnostic accuracy of clinical signs and investigations for functional weakness, sensory and movement disorders: A systematic review

INTRODUCTION

Patients with functional neurological disorders (FND) present with weakness, sensory or movement disorder without corresponding brain pathology. The current classificatory systems suggest an inclusionary approach to diagnose FND. Hence, there is a need to systematically evaluate the diagnostic accuracy of clinical signs and electrophysiological investigations in view of the lack of gold standard tests to diagnose FND.

METHODS

PubMed and SCOPUS databases were searched for studies published from Jan 1950 to Jan 2022 which reported the diagnostic accuracy of clinical signs and electrophysiological investigations in patients with FND. The Newcastle Ottawa scale was used to assess the quality of the studies.

RESULTS

Twenty-one studies (727 cases and 932 controls), of which 16 reported clinical signs and, five reported electrophysiological investigations, were included in the review. Two studies were of good quality, 17 of moderate quality, and two of poor quality. We identified 46 clinical signs (24 in weakness, 3 in sensory, and 19 in movement disorders) and 17 investigations (all in movement disorders). Specificity values for signs and investigations were comparatively high compared to the wide variance in sensitivity values.

CONCLUSION

Electrophysiological investigations appear to have a promising role in diagnosing FND, particularly functional movement disorders. The combined use of individual clinical signs and electrophysiological investigations may support and improve diagnostic certainty of FND. Future research can focus on improving the methodology and validating the existing clinical signs and electrophysiological investigations to enhance the validity of the composite diagnostic criterias for FND diagnosis.

Diagnosis and management of functional neurological disorder

Functional neurological disorder (FND), previously regarded as a diagnosis of exclusion, is now a rule-in diagnosis with available treatments. This represents a major step toward destigmatizing the disorder, which was often doubted and deemed untreatable. FND is prevalent, generally affecting young and middle aged adults, and can cause severe disability in some individuals. An early diagnosis, with subsequent access to evidence based rehabilitative and/or psychological treatments, can promote recovery-albeit not all patients respond to currently available treatments. This review presents the latest advances in the use of validated rule-in examination signs to guide diagnosis, and the range of therapeutic approaches available to care for patients with FND. The article focuses on the two most frequently identified subtypes of FND: motor (weakness and/or movement disorders) and seizure type symptoms. Twenty two studies on motor and 27 studies on seizure type symptoms report high specificities of clinical signs (64-100%), and individual signs are reviewed. Rehabilitative interventions (physical and occupational therapy) are treatments of choice for functional motor symptoms, while psychotherapy is an emerging evidence based treatment across FND subtypes. The literature to date highlights heterogeneity in responses to treatment, underscoring that more research is needed to individualize treatments and develop novel interventions.

Biomarkers in functional movement disorders: a systematic review

Functional movement disorders (FMD) are proposed to reflect a specific problem with voluntary control of movement, despite normal intent to move and an intact neural capacity for movement. In many cases, a positive diagnosis of FMD can be established on clinical grounds. However, the diagnosis remains challenging in certain scenarios, and there is a need for predictors of treatment response and long-term prognosis.In this context, we performed a systematic review of biomarkers in FMD. Eighty-six studies met our predefined criteria and were included.We found fairly reliable electroencephalography and electromyography-based diagnostic biomarkers for functional myoclonus and tremor. Promising biomarkers have also been described for functional paresis, gait and balance disorders. In contrast, there is still a lack of diagnostic biomarkers of functional dystonia and tics, where clinical diagnosis is often also more challenging. Importantly, many promising findings focus on pathophysiology and reflect group-level comparisons, but cannot differentiate on an individual basis. Some biomarkers also require access to time-consuming and resource-consuming techniques such as functional MRI.In conclusion, there are important gaps in diagnostic biomarkers in FMD in the areas of most clinical uncertainty. There is also is a lack of treatment response and prognostic biomarkers to aid in the selection of patients who would benefit from rehabilitation and other forms of treatment.

The utility of electrodiagnostic tests for the assessment of medically unexplained weakness and sensory deficit

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Medically unexplained symptoms (MUS) are challenge for electrodiagnostic testing.

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Weakness and sensory deficit can be manifestations of psychogenic disorders.

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This is a review of electrodiagnostic methods used for the assessment of MUS.

Patients with suspected medically unexplained symptoms or psychogenic disorders are frequently requested to undergo an EMG exam. However, the suspected diagnosis is not always told to the electromyography practitioner, who must be able to recognize such a condition to avoid false positive diagnosis without dismissing the possibility to uncover any true dysfunction. There are many clinical manoeuvers to assess the consistency of the patients’ reported weakness or sensory deficit. The electrodiagnostic practitioner should be aware of those clinical tricks and interpret the electrodiagnostic findings in the clinical context. There are many electrodiagnostic tests that the practitioner can use for the assessment of motor and sensory functions but these tests have also important drawbacks and limitations. Only after a good clinical evaluation would the practitioner be able to give his/her opinion on the clinical relevance of the electrodiagnostic findings. Here we review some of the tests that can help the practitioner to define the electrophysiological characteristics of a suspected functional disorder presenting with weakness or sensory deficit.

Neurologic diagnostic criteria for functional neurologic disorders

The diagnosis of functional neurologic disorders can be challenging. In this chapter we review the diagnostic criteria and rating scales reported for functional/psychogenic sensorimotor disturbances, psychogenic nonepileptic seizures (PNES) and functional movement disorders (FMD). A recently published scale for sensorimotor signs has some limitations, but may help in the diagnosis, and four motor and two sensory signs have been reported as highly reliable. There is good evidence using eight specific signs for the differentiation of PNES from seizures. Recently, diagnostic criteria were developed for PNES; their sensitivity and specificity need to be evaluated. The definitive diagnosis of PNES can be made by recording typical positive features during the spells, and in a low proportion of cases, where the distinction with an organic etiology cannot easily be done, a normal electroencephalogram suggests the diagnosis. FMD diagnosis relies on diagnostic criteria, which have been refined over time and may be supplemented by laboratory tests in some phenotypes. Rating scales for PNES and FMD could be useful for severity measures, but several limitations remain to be addressed.

Functional limb weakness and paralysis

Functional (psychogenic) limb weakness describes genuinely experienced limb power or paralysis in the absence of neurologic disease. The hallmark of functional limb weakness is the presence of internal inconsistency revealing a pattern of symptoms governed by abnormally focused attention. In this chapter we review the history and epidemiology of this clinical presentation as well as its subjective experience highlighting the detailed descriptions of authors at the end of the 19th and early 20th century. We discuss the relevance that physiological triggers such as injury and migraine and psychophysiological events such as panic and dissociation have to understanding of mechanism and treatment. We review many different positive diagnostic features, their basis in neurophysiological testing and present data on sensitivity and specificity. Diagnostic bedside tests with the most evidence are Hoover's sign, the hip abductor sign, drift without pronation, dragging gait, give way weakness and co-contraction.

Interobserver agreement and validity of bedside 'positive signs' for functional weakness, sensory and gait disorders in conversion disorder: a pilot study

BACKGROUND

Conversion disorder (CD) is no longer a diagnosis of exclusion. The new DSM-V criteria highlight the importance of 'positive signs' on neurological examination. Only few signs have been validated, and little is known about their reliability.

OBJECTIVE

The aim was to examine the clinical value of bedside positive signs in the diagnosis of CD presenting with weakness, gait or sensory symptoms by assessing their specificity, sensitivity and their inter-rater reliability.

PATIENTS AND METHODS

Standardised video recorded neurological examinations were performed in 20 consecutive patients with CD and 20 'organic' controls. Ten previously validated sensory and motor signs were grouped in a scale. Thirteen additional motor/sensory 'positive signs', 14 gait patterns and 1 general sign were assessed in a pilot validation study. In addition, two blinded independent neurologists rated the video recordings to assess the inter-rater reliability (Cohen's κ) of each sign.

RESULTS

A score of ≥ 4/14 on the sensory motor scale showed a 100% specificity (CI 85 to 100) and a 95% sensitivity (CI 85 to 100). Among the additional tested signs, 10 were significantly more frequent in CD than controls. The interobserver agreement was acceptable for 23/38 signs (2 excellent, 10 good, 11 moderate).

CONCLUSIONS

Our study confirms that six bedside 'positive signs' are highly specific for CD with good-excellent inter-rater reliability; we propose to consider them as 'highly reliable signs'. In addition 13 signs could be considered as 'reliable signs' and six further signs as 'suggestive signs' while all others should be used with caution until further validation is available.

Psychogenic movement disorders

PURPOSE OF REVIEW

This review describes the main clinical features of psychogenic (functional) movement disorders and reports recent advances in diagnosis, pathophysiology, and treatment.

RECENT FINDINGS

The terminology and definition of patients with psychogenic movement disorders remain subjects of controversy; the term "functional" has been used more frequently in the literature in recent years regarding the neurobiological substrate underpinning these disorders. Correct diagnosis of psychogenic movement disorders should rely not on the exclusion of organic disorders or the sole presence of psychological factors but on the observation or elicitation of clinical features related to the specific movement disorder (ie, a positive or inclusionary rather than exclusionary diagnosis). Sudden onset, spontaneous remissions, and variability over time or during clinical examination are useful "red flags" suggestive of a psychogenic movement disorder. Imaging studies have demonstrated impaired connectivity between limbic and motor areas involved in movement programming and hypoactivity of a brain region that compares expected data with actual sensory data occurring during voluntary movement. Treatment of psychogenic movement disorders begins with ensuring the patient's acceptance of the diagnosis during the initial debriefing and includes nonpharmacologic (cognitive-behavioral therapy, physiotherapy) and pharmacologic options.

SUMMARY

Psychogenic movement disorders represent a challenging disorder for neurologists to diagnose and treat. Recent advances have increased understanding of the neurobiological mechanism of psychogenic movement disorders. Treatment with cognitive strategies and physical rehabilitation can benefit some patients. As short duration of disease correlates with better prognosis, early diagnosis and initiation of treatment are critical.

Positive signs of functional weakness

Functional (conversion) neurological symptoms represent as one of the most common situations faced by neurologists in their everyday practice. Among them, acute or subacute functional weakness may mimic very prevalent conditions such as stroke or traumatic injury. Hence, accurate and reliable positive signs of functional weakness are valuable for obtaining timely diagnosis and treatment, making it possible to avoid unnecessary or invasive tests and procedures up to thrombolysis. We therefore present here a brief overview of the positive neurological signs of functional weakness available, both in the lower and in the upper limbs, moving from a historical perspective to their relevance in current clinical practice.

The value of 'positive' clinical signs for weakness, sensory and gait disorders in conversion disorder: a systematic and narrative review

Experts in the field of conversion disorder have suggested for the upcoming DSM-V edition to put less weight on the associated psychological factors and to emphasise the role of clinical findings. Indeed, a critical step in reaching a diagnosis of conversion disorder is careful bedside neurological examination, aimed at excluding organic signs and identifying 'positive' signs suggestive of a functional disorder. These positive signs are well known to all trained neurologists but their validity is still not established. The aim of this study is to provide current evidence regarding their sensitivity and specificity. We conducted a systematic search on motor, sensory and gait functional signs in Embase, Medline, PsycINfo from 1965 to June 2012. Studies in English, German or French reporting objective data on more than 10 participants in a controlled design were included in a systematic review. Other relevant signs are discussed in a narrative review. Eleven controlled studies (out of 147 eligible articles) describing 14 signs (7 motor, 5 sensory, 2 gait) reported low sensitivity of 8-100% but high specificity of 92-100%. Studies were evidence class III, only two had a blinded design and none reported on inter-rater reliability of the signs. Clinical signs for functional neurological symptoms are numerous but only 14 have been validated; overall they have low sensitivity but high specificity and their use should thus be recommended, especially with the introduction of the new DSM-V criteria.

The elbow flex-ex: a new sign to detect unilateral upper extremity non-organic paresis

OBJECTIVE

To examine a new neurological sign that uses synergistic oppositional movements of the arms to evaluate for non-organic upper extremity weakness.

METHODS

Patients with unilateral arm weakness were tested in a standing or sitting position with the elbows flexed at 30°. The examiner held both forearms near the wrists while asking the patient to flex or extend the normal arm at the elbow and simultaneously feeling for flexion or extension of the contralateral (paretic) arm. In patients with organic paresis, there was not a significant detectable force of contralateral opposition of the paretic limb. Patients with non-organic arm weakness had detectable strength of contralateral opposition in the paretic arm when the normal arm was tested.

RESULTS

The test was first performed on 23 patients with no complaint of arm weakness. Then, 31 patients with unilateral arm weakness were tested (10 with non-organic weakness and 21 with organic weakness). The elbow flex-ex sign correctly identified the cause of weakness in all cases.

CONCLUSIONS

The elbow flex-ex sign is useful in differentiating between functional and organic arm paresis.

Validity of the "Drift without pronation" sign in conversion disorder

Background

Conversion disorder (CD) is a psychiatric disorder, yet the diagnosis cannot be established without the expertise of a neurologist, as distinguishing a functional from an organic symptom relies on careful bedside examination. Joseph Babinski considered the absence of pronator drift as a ‘positive sign’ for hysterical paresis but the validity of this sign has never been evaluated. The aim of this study was to examine the sensitivity and specificity of the “drift without pronation” sign.

Methods

Twenty-six patients with unilateral functional upper limb paresis diagnosed with CD (DSM-IV) and a control group of 28 patients with an organic neurological condition were consecutively included. The arm stabilisation test was performed with arms stretched out in full supination, fingers adducted, eyes closed for 10 seconds. A positive “drift without pronation” sign was defined by the presence of a downward drift without pronation.

Results

All CD subjects (100%) displayed a positive sign when only 7.1% of organic subjects did (Fisher’s p < 0.001). The sign yielded a sensitivity of 100% (95% CI:84%-100%) and a specificity of 93% (95% CI:76%-98%).

Conclusion

The observation of a “drift without pronation” sign is specific for Conversion Disorder and can be of help in making a quick distinction between organic and functional paresis at the bedside.

Relative or absolute? Implications and consequences of the measures adopted to investigate motor overflow

Motor overflow is involuntary overt movement or covert muscle activity that cooccurs with voluntary movement. Overflow is present in several pathological conditions, as well as in neurologically healthy children and older adults, and can be induced in healthy young adults under effortful conditions. This motor phenomenon may provide insight into the underlying mechanisms and kinetic characteristics of voluntary and involuntary motor control in various populations. Although often measured behaviorally using force transduction techniques, different methods of calculating and presenting such overflow data have resulted in seemingly contradictory findings, with limited discussion of the advantages and limitations of different approaches. In this article, the authors examined the relevant literature to highlight significant methodological considerations for authors and readers conducting or appraising this type of research. Issues regarding the interpretation and reporting of findings are also discussed. Researchers are encouraged to continue using behavioral measures to create well-defined variables that enable the study of the kinematic characteristics of overflow, as these may offer promising new ways forward in better characterizing and understanding this intriguing movement phenomenon.