eLetters

574 e-Letters

published between 2016 and 2019

  • An overestimation of diagnosing functional foreign accent syndrome?

    Elucidating the nature of the foreign accent syndrome (FAS) can contribute to improve its diagnosis and treatment approaches. To understand this apparently rare syndrome, McWhirter et al. 1 studied a large case series of 49 subjects self-reporting having FAS. The participants were recruited via unmoderated online FAS support groups and surveys shared with neurologists and speech-language therapists from several countries. Participants completed an online protocol including validated scales tapping somatic symptoms, anxiety and depression, social-occupational function, and illness perception. They were also requested to provide speech samples recorded via computers or smartphones during oral reading and picture description. The overall clinical presentation of FAS in each participant was classified by consensus reached by three authors (2 neuropsychiatrists and 1 neurologist) in (1) “probably functional”, (2) “possibly structural” or (3) “probably structural”, wherein (1) meant no evidence of a neurological event or injury suggestive of a functional disorder but with no spontaneous remission; (2) alluded to the presence of some features suggestive of a functional disorder but with some uncertainty about a possible structural basis; and (3) denoted the evidence of a neurological event or injury coincident with the onset of FAS. The recorded speech samples were examined by experts to diagnose FAS and their frequent associated speech-language deficits (apraxia of speech, dysar...

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  • Authors' response to 'An overestimation?'

    We, the authors, thank Berthier for his comments on our study of 49 individuals with self-reported Foreign Accent Syndrome.

    In response, we would first like to clarify that we do not use Berthier’s term ‘psychogenic’, but ‘functional’ in our paper, referring to foreign accent symptoms due to changes in neural function rather than (or in addition to) the direct effects of a structural lesion. The body-mind dualism implied by the terms ‘psychological/psychogenic’ vs ‘neurogenic’ no longer holds water. Berthier himself notes that the differentiation between “functional” and “structural” may be artificial and that there has been great progress in “unveiling of the neural basis” of functional disorders. As we frequently emphasise in explaining the diagnosis to individuals with functional neurological disorders, their symptoms are definitely ‘real’; not ‘imagined’; and have a basis in changes in neural function which we are beginning to understand more clearly [1,2].

    We accept the limitations provided by our method of data collection, including limited data about investigations and a likelihood of selection bias where those with predominantly functional FAS may be somewhat over-represented in our sample. We wish to clarify, however, that cases were classified as ‘probably functional’ on the basis of reported positive clinical features of a functional disorder (e.g. periods of return to normal accent, adoption of stereotypical behaviours) and not by the presence...

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  • The utility of CSF biomarkers in idiopathic normal pressure hydrocephalus?

    Dear Editor,
    The original article by Jeppsson et al. provides substantial perspectives regarding the diagnostic
    significance of cerebrospinal fluid (CSF) biomarkers in discriminating patients with idiopathic normal pressure hydrocephalus (iNPH) from patients with other neurodegenerative disorders. 1 They have found that patients with iNPH had, compared with healthy individuals, lower concentrations of P-tau and APP-derived proteins in combination with elevated MCP-1 1. Moreover, compared with the non-iNPH disorders group, iNPH was characterized by the same significant change; low concentration of tau proteins and APP-derived proteins, and elevated MCP-1. I sincerely appreciate the authors for conducting such a large-scale study of a strictly interesting topic. However, I would like to make some comments hoping to provide a better understanding of some points and some perspectives to be kept in mind while planning future related studies
    In my opinion, the investigation of CSF biomarkers in patients with iNPH may provide several insights in addition to discriminating the iNPH patients from other neurodegenerative diseases. Certainly, these study results may give the opportunity to understand the unknown pathophysiological aspects of iNPH, thereby, even leading to new classifications of the disease. Actually, there may be many questions to be clarified regarding diagnostic approach, evaluation of the iNPH patients and even identification of the disease. 2,3...

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  • Reducing Uncertainty and Expanding Patient Engagement in Deep Brain Stimulation Trials for Tourette Syndrome

    We appreciate the editorial by Dr. Muller-Vahl [1] about our recent article [2]. The large, international study group who co-authored our paper collectively felt that it would be useful to provide clarification of a few important points regarding the International Tourette Syndrome (TS) Deep Brain Stimulation (DBS) Database and Registry, the International Neuromodulation Registry, and our published analysis.

    There is widespread agreement on the need for more randomized controlled trials (RCTs) to evaluate the efficacy of DBS for many indications, including TS, and there has been substantial discussion in the medical community about how these trials should be organized and carried out [3]. Our approach to overcome the challenges with the modest amount of data available for surgical therapies for TS has been to use symbiotic data sharing [4]. This approach encourages the broadening of investigative teams after publication of clinical studies to perform additional analyses and to develop new hypotheses. The key concept behind this approach is that new investigators work in a close, collaborative relationship with the teams that conducted the initial data collection. In addition, a recent viewpoint from the Food & Drug Administration in the United States reported that “For some devices, opportunities exist for leveraging alternative data sources, such as existing registries or modeling techniques, to allow regulators to have a good idea of the risks and benefits of...

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  • Seizures and movement disorders : cortico-subcortical networks

    Seizures and movement disorders : cortico-subcortical networks

    Dr Aileen McGonigal

    Aix Marseille Univ, Inserm, INS, Institut de Neurosciences des Systèmes, Marseille, France
    APHM, Timone Hospital, Clinical Neurophysiology, Marseille, France

    Corresponding author: Dr Aileen McGonigal, Service de Neurophysiologie Clinique, CHU Timone, AP-HM, Marseille, France
    Email : aileen.mcgonigal@univ-amu.fr
    Tel: 00 33 491384995
    Fax:00 33 491385826

    To the Editors

    I was interested to read the recent review by Dr Freitas and colleagues1. This interesting article highlights diagnostic challenges, clinical overlap and possible shared pathophysiological processes in epileptic seizures and movement disorders. I would like to add a couple of points that seem important to acknowledge.
    Firstly, in terms of clinical expression, the authors rightly mention that automatic movements occurring during focal epileptic seizures can sometimes resemble those seen in certain movement disorders, and they give the examples of orofacial automatisms (most often seen in temporal lobe seizures), as well as hyperkinetic behaviors. While the authors highlight sleep-related epilepsy as the main cause of hyperkinetic behavior, in fact hyperkinetic behavior may be seen in seizures from various cortical origins both in wakefulness and in sleep. It should be recognized that especially (though not exclusivel...

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  • Split weakness signs in ALS
     I note the clinical analysis of differential weakness in ALS in elbow flexion (biceps brachii) compared to elbow extension (triceps) reported by Khalaf et al.1 This is described as analogous to similar 'split' muscle weakness around the ankle joint and, particularly, as that found in flexor digitorum indicis (FDI) compared to abductor digit minim (ADM) in the hand in the disease. It should be remembered that, although characteristic of ALS, this differential pattern of weakness has repeatedly been found not to be unique to ALS, even from the first descriptions.2,3 As the authors, and Vucic in his editorial remark,1,4 the cause of this interesting pattern of weakness in ALS remains uncertain. The finding of an association between the pattern of weakness and increased excitability in the upper motor neuron system in ALS does not necessarily provide primary support for an upper motor neuron (UMN) causation.  Nonetheless this pattern of weakness must be important in the disease. It is worth remembering that differential susceptibility to neurogenic lower motor neuron weakness is also a characteristic feature of some peripheral neuropathies, e.g., the Charcot-Marie-Tooth syndromes. Furthermore, differential muscle weakness and atrophy is a characteristic finding that is important in clinical diagnosis in the myriad different genetically determined muscular dystrophies.5 Although the causation of this differential susceptibility of certain muscles in this la...
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  • Reply to: The Movement disorder associated with NMDAR antibody-encephalitis is complex and characteristic: an expert video-rating study

    We read with interest the description of the movement disorder manifestations in patients with N-methyl-D-aspartate receptor antibody mediated encephalitis (NMDAR-AbE) by a panel of movement disorders experts (1). The authors conclude that the co-existence of dystonia, chorea and stereotypies within the same patient, variability in phenomenology within the course of a single day and evolution over time, are helpful pointers to the diagnosis of NMDAR-AbE and therefore early treatment. We agree with this conclusion. However, this analysis overlooks consideration of the distinctive, if not unique, phenomenology of the “classical” movement disorder of NMDAR-AbE (2).

    In our earlier description of this complex movement disorder we reported the presence of variable, complex, jerky semi-rhythmic bulbar and limb movements, associated with posturing and oculogyric crises, but in summarising the overall clinical syndrome we deliberately avoided conventional movement disorder terms because none captured the entire clinical picture (2). Classification of a movement disorder, particularly when complex, is guided by the most obvious, dominant or overwhelming clinical feature. The ‘classical’ movement disorder in NMDAR-AbE is complex but as acknowledged by the expert reviewers, is not typical of any of the movement disorder categories (1). Stereotypies are purposeless repetitive motor behaviours that occur when awake and are interrupted by a shift in attention or distraction. Dy...

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  • The complex NMDAR-antibody associated movement disorder is highly-distinctive

    We thoroughly enjoyed reading the comment on our paper which analysed expert ratings of the movement disorder associated with NMDAR antibody-encephalitis.1 Thompson et al’s elegant pathophysiological explanation provides an excellent framework of the most plausible neural structures involved in NMDAR-antibody encephalitis. Further, they note these movements can occur in semi-conscious patients, and this concurs well with the previous description of anti-gravity movements in the context of ‘status dissociatus’.2 A review of our 76 videos, revealed Thompson et al’s account of “variable, complex jerky semi-rhythmic movements….in the obtunded state” in 45 (59%) of cases. Therefore, this complex description was not present in almost half of patients. Furthermore, our recent clinical experiences note some NMDAR-antibody patients with abnormal movements but without obtundation: perhaps, given the known stepwise progression of many cases, this is a function of increasingly early disease recognition.3

    By contrast to Thompson et al, our published study design intentionally used conventional phenomenological terms to define the movement disorder associated with NMDAR antibody-encephalitis.1 This approach aimed to define a pragmatic method, available to all clinicians, which could identify and faithfully communicate this complex movement disorder, with the important aim of earlier disease recognition. The results identified a dominant set of recognised classifications – dyston...

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  • Models for predicting risk of dementia: improvement still needed

    Hou et al. are to be commended for an in-depth systematic review of currently available dementia risk models that quantify the probability of developing dementia, covering both studies on community-dwelling individuals as well as clinic-based MCI studies.1 One of the key conclusions was that “the predictive ability of existing dementia risk models is acceptable, but the lack of validation limited the extensive application of the models for dementia risk prediction in general population or across subgroups in the population.” Based on recent insights, we believe that the discriminative ability of existing dementia prediction models in the general population is currently not acceptable for clinical use.

    We recently validated four promising dementia risk models (CAIDE, ANU-ADRI, BDSI, and DRS).2 In addition to external validation of these models in the Dutch general population, we also sought to investigate how these models compared to predicting dementia based on the age component of these models only. We found that full models do not have better discriminative properties than age alone. As such, we would like to make three suggestions to establish a reliable dementia prediction model.

    First, prediction models typically only report model performance on the basis of a full model.1-4 For dementia risk, however, age plays a pivotal role. Therefore, any new model should compare its predictive accuracy to age alone.

    Second, the setting in which a prediction...

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  • Area postrema syndrome: another feature of anti-GFAP encephalomyelitis

    Dear Editor,

    We read with great interest the recent paper of Sechi et al. that describes 13 patients with anti-GFAP related myelitis and compares them with 41 patients with anti-AQP4 related myelitis.1 To date, very little data is available about anti-GFAP related disorders.2-3 Sechi et al. highlight some differences between the two entities to help clinicians differentiate them.1 One of these clinical differences relates to area postrema syndrome (APS). Indeed, it is well known that APS is a classical feature of neuromyelitis optica spectrum disorders, particularly among anti-AQP4 positive patients.4 Sechi et al. report this syndrome as a prodromal event in 20% of anti-AQP4 related myelitis. Conversely, the authors do not report any case of APS preceding or accompanying myelitis related to anti-GFAP.1 Given these data, APS could be an indicator for ruling out anti-GFAP encephalomyelitis, particularly useful for centers that do not yet have access to biological testing for anti-GFAP Abs.
    However, we report the case of a 41-year-old woman who in April 2016 developed intractable nausea and vomiting lasting for five weeks and leading to 35 kilograms in weight loss. An extensive search for a digestive disease was negative, and no neurological explorations were performed. One month following the resolution of digestive symptoms, she developed mental confusion, diplopia, dysarthria, dizziness, bilateral blurred vision (with optic disc edema) and paraparesis. Brain...

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