eLetters

572 e-Letters

  • No laughing matter

    In their recent article on the pathogenesis of dystonia, Kaji and colleagues argue that aberrant cerebellar inputs can induce dystonic movement mediated by the basal ganglia.[1] In this framework, the sensory trick (geste antagoniste) leads to a realignment between predicted and actual sensory information, thus reduces (or overrides) the sensorimotor mismatch forwarded to the basal ganglia, and in turn alleviates dystonic contractions.
    A similar model of sensorimotor mismatch response has been implicated in the physiology of being tickled[2]. Specifically, it has been proposed that the inability to tickle oneself is related to a sensory attenuation mediated by the cerebellum during self-generated tactile sensation[3]. This attenuation is proportional to the precision of the sensory prediction[4]. Whether the same cerebellar processes are responsible for the alleviation of dystonia during a sensory trick would be an interesting question to explore experimentally. At the risk of straining the analogy, one could even describe the postures and movements one produces when being tickled as dystonic-like. Neurologists are reminded of this when interpreting ambiguous plantar responses in very ticklish patients -- a problem that can be avoided by employing the patient's cerebellar sensory attentuation[5].

    1. Kaji R, Bhatia K, Graybiel AM. Pathogenesis of dystonia: is it of cerebellar or basal ganglia origin? J Neurol Neurosurg Psychiatry. 2017 Oct 31. pii: jnnp-20...

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  • “Region of interest” approach in cerebellar meta-analysis

    In our previous meta-analysis of cerebellar atrophy in seven major neurodegenerative conditions (Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Huntington’s disease (HD), Parkinson’s disease (PD), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP)) we investigated studies that reported grey matter (GM) loss in the cerebellum [1]. Consistent regions of atrophy were found in AD, ALS, FTD, MSA, and PSP but not HD or PD. In their comment on our meta-analysis, Sheng and Pan have argued that our method of selectively investigating studies that found cerebellar atrophy, rather than adopting a whole-brain approach, is “not optimal in a coordinate-based meta-analysis” [2]. They further cite previous whole-brain meta-analyses that did not identify clusters of cerebellar grey matter loss in patients [3-6].
    Here, we argue that our approach was justified given our aim, which was to focus on cases where cerebellar atrophy was found in the respective disease groups in order to determine 1) if such atrophy followed a consistent, robust pattern, and 2) if atrophy patterns were disease-specific or generic, where possible relating them to symptomatology.
    There are several reasons why we chose to focus on the cerebellum rather than adopting a whole-brain approach. First, the cerebellum is hardly a “region of interest” in the classical sense given its marked heterogeneity in terms of function and connectivity as we...

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  • Does Cerebellar Atrophy in Neurodegeneration?

    Does Cerebellar Atrophy in Neurodegeneration?

    Li-Qin Sheng1, Ping-Lei Pan2
    1 Department of Neurology, Traditional Chinese Medicine Hospital of Kunshan, Kunshan, PR China
    2 Department of Neurology, Affiliated Yancheng Hospital, School of Medicine, Southeast University, Yancheng, PR China

    Correspondence:
    PingLei Pan, Department of Neurology, Affiliated Yancheng Hospital, School of Medicine, Southeast University, West Xindu Road 2#, Yancheng, Jiangsu Province, 224001, PR China. E-mail: panpinglei@163.com, Telephone: +8618361146977

    Coordinate-based meta-analysis is a powerful way for neuroimaging studies to identify the most consistent and replicable differences in brain activity or structure in neurodegenerative disorders. In their JNNP publication, Gellersen et al 1 conducted coordinate-based meta-analyses of 54 voxel-based morphometry (VBM) studies in Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), behavioral variant frontotemporal dementia (bvFTD), amyotrophic lateral sclerosis (ALS), multiple system atrophy (MSA), and progressive supranuclear palsy (PSP). In this study, they solely focused on cerebellar grey matter (GM) atrophy.1 Marked cerebellar atrophy in AD, ALS, bvFTD, PSP and MSA, but not in PD or HD, was identified in the meta-analyses.1
    These findings are of interest.1 However, the procedure of the meta-analyses had a major limitation. Coordin...

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  • What is the evidence for neurological follow-up of patients with FNS?

    We thank dr. Coebergh and colleagues for their interest in our study. We agree that(a) there are many differences between the health care systems of the UK and the Netherlands, (b) the results of our study do not apply to excluded patients, and (c) the management of new neurological symptoms, relapses of previous FNS and relevant neurological and other co-morbidities remain very important in order to prevent inappropriate re-referrals and investigations of patients. However, in the absence of sound evidence from appropriate clinical studies,we disagree with the authors’ conclusion that neurological follow-up of these patients is often beneficial.
    We wish to emphasize that in our study, firstly a neurologist established the diagnosis and briefly explained the diagnosis to the patient. Secondly, the first neurologist referred the patient to a specially trained second neurologist, who scheduled half an hour to discuss the diagnosis with the patient. This approach is clearly different from immediate referral to a GP after the diagnosis.

  • Neurologists have an important role in follow up of patients with functional neurological symptoms.

    It is good to see that trials are being done to answer the critical question of how best to provide care for those patients with functional neurological symptoms (FNS). The research paper, ‘Management of patients with functional neurological symptoms: a single-centre randomised controlled trial’, by Pleizier, de Haan and Vermeulen, randomizes outpatients with functional neurological symptoms after diagnosis, to either two outpatient appointments with a neurologist, or referral back to a GP. Intriguingly, it finds no difference in outcome, that is quality of life scores, between the two groups.[1] While this study attempts to address an important question, namely the role of the neurologist in the care of patients with functional neurological disorders, we feel it has a number of problems that limit its generalizability, particularly to UK neurology practice.
    The Netherlands is a country that compared to the UK, has approximately four times as many neurologists per head of the population, and many more GPs with higher levels of job satisfaction,[2] and often have mental health nurse support in the practice itself. Neurology outpatient waiting times are shorter in the Netherlands, and in-patient neurology review happens routinely and is quicker, unlike in the UK where it may not occur at all.[3] Because of this lack of prompt neurological review in the UK, it is common for patients to receive erroneous diagnoses, often necessitating an “undiagnosis” at the eventual neu...

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  • Re:Accumulation of MRI Markers of Cerebral Small Vessel Disease in Depression
    Xin Xu

    We agree that an evaluation of the total cerebrovascular disease (CeVD) burden is important to understand the effect of brain structural abnormalities on clinical outcomes such as cognitive impairment and neuropsychiatric disorders. Recently, integrated measures of total brain MRI burden have been employed to understand neuropathological changes in elderly. However, global CeVD burden may not be best measured by the sim...

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  • Re: A Val30Met sporadic familial amyloid polyneuropathy case with atypical presentation: Upper limp onset of symptoms
    Erdi Sahin

    Transthyretin-related familial amyloid polyneuropathy (TTR-FAP) is an autosomal dominant disorder caused by the mutations of the transthyretin (TTR) gene. The mutant amyloidogenic TTR protein causes systemic accumulation of amyloid fibrils that result in organ dysfunction [1]. Over 100 mutations in TTR gene are associated with the disease but still, the first identified Val30Met mutation make up 50% of the cases worldwide....

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  • Accumulation of MRI Markers of Cerebral Small Vessel Disease in Depression
    Zhiwei Xia

    In a study published in J Neurol Neurosurg Psychiatry, Xu et al.1 aimed to investigate the relation between microbleeds (CMBs) and Neuropsychiatric symptoms (NPS) in an elderly population, through a cross- sectional study related to 802 participants. Interestingly, they found a statistically significant increment of the incidence of depression, with the presence of multiple CMBs, in particular lobar CMBs. This finding is...

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  • Re:Deep brain stimulation as a feedback control system
    Simon J Little

    We are very grateful to Dr Keller for his comments and support for the feedback control approach to deep brain stimulation for Parkinson's disease. As he points out, "reducing or turning off the stimulation current when it is not needed conforms to the clinical axiom if it ain't broke, don't fix it". This is further borne out by a publication currently in press in this journal in which we show that feedback-controlled dee...

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  • Correction
    Narayan Rao Rao

    It is mentioned that Sherrington introduced the term Synapse. In fact the word synapse was introduced By Macheal Foster,then Professor of Physiology at Cambridge along with his mentor Arthur Woodllgar Verrall coined the word Synapse,meaning Clasp.Thus Sherrington made no such discovery,and is ti be credited only with having solicited the name. As he was working on Reflexes,he has advocated the physiological concept of Syn...

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