Update on functional vestibular and gait disorders.

Functional gait disorders are common in clinical practice. They are also usually disabling for affected individuals. The diagnosis is challenging because no single walking pattern is pathognomonic for a functional gait disorder. Establishing a diagnosis is based not primarily on excluding organic gait disorders but instead predominantly on recognizing positive clinical features of functional gait disorders, such as an antalgic, a buckling, or a waddling gait. However, these features can resemble and overlap with organic gait disorders. It is therefore necessary to also look for inconsistency (variations in clinical presentation that cannot be reconciled with an organic lesion) and incongruity (combination of symptoms and signs that is not seen with organic lesions). Yet, these features also have potential pitfalls as inconsistency can occur in patients with dystonic gait or those with freezing of gait. Similarly, patients with dystonia or chorea can present with bizarre gait patterns that may falsely be interpreted as incongruity. A further complicating factor is that functional and organic gait disorders may coexist within the same patient. To improve the diagnostic process, we present a sign-based approach—supported by videos—that incorporates the diverse clinical spectrum of functional gait disorders. We identify 7 groups of supportive gait signs that can signal the presence of functional gait disorders. For each group of signs, we highlight how specific clinical tests can bring out the inconsistencies and incongruencies that further point to a functional gait disorder.

Functional movement and gait disorders: A matter of age?

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

Chapter 27 - Functional (psychogenic) gait disorder: diagnosis and management

P124. Evaluation of gait parameters in functional gait disorders

Functional gait disorders (FGD) are a common and disabling condition. Consensus-based rehabilitation techniques for treating FGD and other functional neurological disorder presentations at large utilize a variety of therapeutic strategies, including distraction, novel approaches to movement, entrainment, stress/hypervigilance modulation, and psychotherapy. Here we present a case of a 24-year-old woman with a complex history of anxiety, depression, left frontal astrocytoma, postural orthostatic tachycardia syndrome (POTS) and FGD. During a multidisciplinary inpatient rehabilitation stay for FGD, the patient underwent rhythmic auditory stimulation (RAS) delivered by a neurologic music therapist in conjunction with physical therapy, occupational therapy, and psychotherapy. The RAS intervention appeared to play a significant role in symptom resolution for this patient. Improvement in the patient's truncal displacement, foot dragging, and well as overall gait speed occurred following serial RAS trials performed over a single treatment session. Benefits persisted immediately following the intervention and upon subsequent reassessment. Although at four-year follow-up the patient's FGD symptoms remained resolved, fatigue continued to limit her ambulatory capacity and overall endurance. RAS represents a unique therapeutic approach for treating FGD, complementary to existing consensus-based rehabilitation recommendations, and may warrant further consideration by the field.

This scientific commentary refers to ‘Dissociated motor learning and de-adaptation in patients with functional gait disorders’, by Lin etal. (doi:10.1093/brain/awaa190)

Functional gait disorders (FGDs) are relatively common in patients presenting for evaluation of a functional movement disorder (FMD). The diagnosis and classification of FGDs is complex because patients may have a primary FGD or a FMD interfering with gait. We performed a detailed evaluation of clinical information and video recordings of gait in patients diagnosed with FMDs. We studied a total of 153 patients with FMDs, 68% females, with a mean age at onset of 36.4years. A primary FGD was observed in 39.2% of patients; among these patients, 13 (8.5%) had an isolated FGD (a gait disorder without other FMDs). FMDs presented in 34% of patients with otherwise normal gait. Tremor was the most common FMD appearing during gait, but dystonia was the most common FMD interfering with gait. Patients with FGD had a higher frequency of slow-hesitant gait, astasia-abasia, bouncing, wide-based gait and scissoring compared with patients with FMDs occurring during gait. Bouncing gait with knee buckling was more frequently observed in patients with isolated FGD (P = 0.017). Patients with FGDs had a trend for higher frequency of wheelchair dependency (P = 0.073) than those with FMDs interfering with gait. Abnormal gait may be observed as a primary FGD or in patients with other FMDs appearing during gait; both conditions are common and may cause disability.

Functional gait disorders: Demographic and clinical correlations

Differential resting-state functional connectivity patterns in functional movement disorders: Evidence for gait-disorder-specific aberrations.

IntroductionSubacute combined degeneration (SCD) of the spinal cord is a well-known neurological disorder commonly associated with vitamin B12 deficiency. However, the condition can also present in individuals with normal B12 levels, making diagnosis more difficult.ObjectivesThis paper aims to examine the diagnostic challenges posed by subacute combined degeneration of the spinal cord in patients with normal B12 levels. Specifically, it aims to highlight the importance of early screening for nitrous oxide use and the complexities introduced by co-occurring functional gait disorders.MethodsLiterature research was conducted using PubMed databases. The following keywords were used “whippets” or “nitrous oxide” or “inhalant use disorder”, and “subacute degeneration of spinal cord” and/ or “normal B12 levels”. Furthermore, a comprehensive clinical evaluation was conducted, including a detailed inquiry into the patient’s substance use history.ResultsThe 56-year-old patient developed symptoms of subacute combined degeneration (SCD) despite normal B12 levels. He experienced worsening tingling sensations, starting in the extremities and moving upward, along with new gait instability requiring a cane. Initially denying substance use, he later admitted to daily nitrous oxide inhalation, which disrupts B12 metabolism and causes spinal demyelination, leading to neurological deficits even with normal B12 levels. The presence of a functional gait disorder complicated the diagnosis, but persistent questioning about substance use and recognizing the effects of nitrous oxide were key to accurate diagnosis.ConclusionsThis case highlights the importance of early and comprehensive substance use screening, particularly in patients presenting with unexplained neurological symptoms. The disruption of B12 metabolism by nitrous oxide can cause significant spinal cord degeneration, even when serum B12 levels are normal. This underscores the need for detailed, persistent questioning about substance use in clinical settings, particularly for patients with risk factors for inhalant abuse. Additionally, an awareness of the multifaceted nature of functional gait disorders is essential for accurate diagnosis and optimal patient outcomes. Routine screening for nitrous oxide use and a thorough examination of gait abnormalities can aid in the timely detection and treatment of subacute spinal degeneration, preventing further neurological damage. By incorporating recommended screening questions and being vigilant about the neurological effects of nitrous oxide, clinicians can better address the diagnostic challenges of SCD and functional gait disorders.Disclosure of InterestNone Declared

Mal de débarquement syndrome diagnostic criteria: Consensus document of the Classification Committee of the Bárány Society

Background Functional Gait Disorders (FGD) are a common presentation of motor-Functional Neurological Disorders (motor-FND) that affect walking ability. Aim To provide a narrative review of the current literature on FGD. Methods A narrative overview of published literature was undertaken, based on a systematic search of relevant databases, authoritative texts and citation tracking. Results FGD is multidimensional and disabling, with numerous phenotypes described in the literature, including ‘knee buckling,’ ‘astasia-abasia’ and ‘excessive slowness.’ Motor symptoms such as weakness or tremor, and non-motor symptoms, such as pain and fatigue may contribute to the disability and distress in FGD. Phenotypic features and clinical signs are seen in FGD that demonstrate inconsistency and incongruity with structural disease. A limited number of treatment studies have specifically focussed on FGD, however, reporting of outcomes from motor-FND cohorts has demonstrated short and long-term improvements in walking ability through multidisciplinary rehabilitation. Conclusions The relative contribution of motor and non-motor symptoms in FGD remains unknown, but it is likely that non-motor symptoms increase the illness burden and should be considered during assessment and treatment. Recommended treatment for FGD involves multidisciplinary rehabilitation, but optimum treatment elements are yet to be determined.

This article outlines recent developments in the clinical and automated assessment of neurological gait disorders. With a primary focus on vestibular, cerebellar, and functional gait disorders, we discuss how instrumented gait examination may assist clinical decision making in these disorders with respect to the initial differential diagnosis and prognosis as well as the objective monitoring of disease progression and therapeutic interventions. We delineate strategies for data handling and analysis of quantitative gait examinations that can facilitate the clinical characterization and interpretation of walking impairments. These strategies include data normalization and dimensionality reduction procedures. We further emphasize the value of a comprehensive, standardized gait assessment protocol. Accordingly, the examination of walking conditions that challenge patients with respect to their biomechanical, sensory, or cognitive resources are particularly helpful to disclose and characterize the causes underlying their gait impairment. Finally, we provide a perspective on the emerging implementation of pattern recognition approaches within the framework of clinical management of gait disorders and discuss their potential to assist clinical decision making with respect to the differential diagnosis and the prognosis of fall risk in individual patients.

Functional gait disorders (FGDs) are a disabling subset of Functional Neurological Disorders in which presenting symptoms arise from altered high-level motor control. The dual-task paradigm can be used to investigate mechanisms of high-level gait control. The study aimed to determine the objective measures of gait that best discriminate between individuals with FGDs and healthy controls and the relationship with disease severity and duration. High-level spatiotemporal gait outcomes were analyzed in 87 patients with FGDs (79.3% women, average age 41.9±14.7 years) and 48 healthy controls (60.4% women, average age 41.9±15.7 years) on single and motor, cognitive, and visual-fixation dual tasks. The area under the curve (AUC) from the receiver operator characteristic plot and the dual-task effect (DTE) were calculated for each measure. Dual-task interference on the top single-task gait characteristics was determined by two-way repeated measures ANOVA. Stride time variability and its standard deviation (SD) failed to discriminate between the two groups in single and dual-task conditions (AUC<0.80 for all). Significant group x task interactions were observed for swing time SD and stride time on the cognitive dual tasks (p<0.035 for all). Longer disease duration was associated with poor gait performance and unsteadiness in motor and cognitive DTE (p<0.003) but improvement in stride length and swing time on the visual dual tasks (p<0.041). Our preliminary findings shed light on measures of gait automaticity as a diagnostic and prognostic gait biomarker and underline the importance of early diagnosis and management in individuals with FGDs.