Monica Angelini

Absence of co-morbidity of Parkinson disease and restless legs syndrome: a case–control study in patients attending a movement disorders clinic

We have carried out a case–control survey of the prevalence of restless legs syndrome (RLS) in 118 Parkinson’s disease out-patients with different stage of disease severity by using the International restless legs syndrome Study Group clinical criteria. This study failed to demonstrate a significantly augmented prevalence of either primary and secondary restless legs syndrome pooled together or primary restless legs syndrome alone among Parkinson’s disease patients as compared to age and gender matched controls. The results of our survey do not confirm a significant co-morbid occurrence of the two disorders. However, an unavoidable limitation of this and all previous studies is that most of the patients examined were already treated with dopaminomimetic drugs, which could have abolished a mild unrecognized RLS anteceding the diagnosis of Parkinson’s disease or possibly masked the subsequent emergence of the sensory-motor disorder following the onset of Parkinson’s disease.

Motor Inhibition during Overt and Covert Actions: An Electrical Neuroimaging Study

Given ample evidence for shared cortical structures involved in encoding actions, whether or not subsequently executed, a still unsolved problem is the identification of neural mechanisms of motor inhibition, preventing “covert actions” as motor imagery from being performed, in spite of the activation of the motor system. The principal aims of the present study were the evaluation of: 1) the presence in covert actions as motor imagery of putative motor inhibitory mechanisms; 2) their underlying cerebral sources; 3) their differences or similarities with respect to cerebral networks underpinning the inhibition of overt actions during a Go/NoGo task. For these purposes, we performed a high density EEG study evaluating the cerebral microstates and their related sources elicited during two types of Go/NoGo tasks, requiring the execution or withholding of an overt or a covert imagined action, respectively. Our results show for the first time the engagement during motor imagery of key nodes of a putative inhibitory network (including pre-supplementary motor area and right inferior frontal gyrus) partially overlapping with those activated for the inhibition of an overt action during the overt NoGo condition. At the same time, different patterns of temporal recruitment in these shared neural inhibitory substrates are shown, in accord with the intended overt or covert modality of action performance. The evidence that apparently divergent mechanisms such as controlled inhibition of overt actions and contingent automatic inhibition of covert actions do indeed share partially overlapping neural substrates, further challenges the rigid dichotomy between conscious, explicit, flexible and unconscious, implicit, inflexible forms of motor behavioral control.

Unexplained dyspnea in an old patient with recurrent stroke: platypnea–orthodeoxia syndrome and evidence of patent foramen ovale

Platypnea–orthodeoxia is a syndrome characterized by dyspnea and hypoxemia in orthostatism relieved by supine position. This phenomenon is frequently associated with interatrial communication, mainly patent foramen ovale. The association of platypnea–orthodeoxia syndrome with recurrent stroke and patent foramen ovale is extremely uncommon. A 73-year-old woman experienced recurrent attacks of dyspnea after an ischemic stroke. Arterial blood gas analysis changes in upright and supine position confirmed the diagnosis of platypnea–orthodeoxia syndrome. Contrast-enhanced transthoracic echocardiography showed patent foramen ovale with atrial septal aneurysm and right-to-left shunt. Percutaneous closure of patent foramen ovale led to stabilization of blood oxygen saturation and resolution of dyspnea. Platypnea–orthodeoxia syndrome should be considered in patients with stroke and unexplained dyspnea. The diagnosis could lead to correction of an unknown cardiac defect and of potential risk factor for stroke.

Restless legs syndrome and Parkinson's disease.

We were highly surprised on reading the recent article by Peralta et al., in which an augmented prevalence of restless legs syndrome (RLS) in patients with Parkinson’s disease (PD) has been reported, without mentioning at all (and consequently having excluded) the well-established conditions causing secondary forms of the sensory-motor disorder, possibly occurring in the patients studied, and without including their own control population. This could have biased the results producing an overestimate of the frequency of assumed ‘‘primary’’ RLS in their patients, consequently corroborating the currently controversial issue of a significant comorbid association between the two disorders. Indeed, in our recently published survey on 118 PD outpatients the exclusion of secondary causes of RLS, and therefore, only considering the assumed ‘‘primary’’ forms of the disorder, resulted in a further reduced statistically not significant frequency of RLS in PD patients. In addition, in our study, only a limited proportion of PD patients, that is, 30 of 118 (25.4%), presented with motor fluctuations such as levodopa (L-dopa) end-of-dose deterioration, and among them only one patient, that is, 3.3%, was found suffering from assumed ‘‘primary’’ RLS. In contrast, the finding that in the study by Peralta et al. the majority of PD patients with RLS-like symptoms, that is 20 of 28 (71.4%), were presenting with Ldopa-related motor fluctuations or, conversely, that 28 of 75 patients, (37.3%) with motor fluctuations scored positive for RLS indicates that the occurrence of confounding conditions, that is, ‘‘mimics’’ of RLS, were particularly relevant in their population of PD patients. Therefore, the conclusion of the authors that their study ‘‘suggests that RLS-like symptoms are part of the sensory-motor spectrum of wearing-off in Ldopa treated PD’’ only confirms the well-known notion that ‘‘mimics’’ of RLS may confound the detection of ‘‘true’’ RLS in these patients, making, in our opinion, the results of their study, as well as those of some others in which the presence of motor fluctuations has not been quoted poorly reliable in supporting the comorbid association of PD and assumed ‘‘primary’’ RLS. Because of these considerations, it would have been preferable to have titled the paper by Peralta et al. ‘‘Restless Legs-like Syndrome in Parkinson’s Disease.’’

Proactive Control Strategies for Overt and Covert Go/NoGo Tasks: An Electrical Neuroimaging Study.

Proactive and reactive inhibition are generally intended as mechanisms allowing the withholding or suppression of overt movements. Nonetheless, inhibition could also play a pivotal role during covert actions (i.e., potential motor acts not overtly performed, despite the activation of the motor system), such as Motor Imagery (MI). In a previous EEG study, we analyzed cerebral activities reactively triggered during two cued Go/NoGo tasks, requiring execution or withholding of overt or covert imagined actions, respectively. This study revealed activation of pre-supplementary motor area (pre-SMA) and right inferior frontal gyrus (rIFG), key nodes of the network underpinning reactive inhibition of overt responses in NoGo trials, also during MI enactment, enabling the covert nature of the imagined motor response. Taking into account possible proactive engagement of inhibitory mechanisms by cue signals, for an exhaustive interpretation of these previous findings in the present study we analyzed EEG activities elicited during the preparatory phase of our cued overt and covert Go/NoGo tasks. Our results demonstrate a substantial overlap of cerebral areas activated during proactive recruitment and subsequent reactive implementation of motor inhibition in both overt and covert actions; also, different involvement of pre-SMA and rIFG emerged, in accord with the intended type (covert or overt) of incoming motor responses. During preparation of the overt Go/NoGo task, the cue is encoded in a pragmatic mode, as it primes the possible overt motor response programs in motor and premotor cortex and, through preactivation of a pre-SMA-related decisional mechanism, it triggers a parallel preparation for successful response selection and/or inhibition during the response phase. Conversely, the preparatory strategy for the covert Go/NoGo task is centered on priming of an inhibitory mechanism in rIFG, tuned to the instructed covert modality of motor performance and instantiated during subsequent MI, which allows the imagined response to remain a potential motor act.

Dry mouth as an initial sign of food-borne botulism: a case report and review of the literature.

Botulism is a rare neuroparalytic disease caused by a potent neurotoxin produced by Clostridium botulinum. There are different clinical types of botulism. Early diagnosis of the condition is essential for effective treatment. We report a case of food-borne botulism in identical twins characterized by severe initial oral involvement and a review of the literature about the condition.

Correction: Proactive Control Strategies for Overt and Covert Go/NoGo Tasks: an Electrical Neuroimaging Study

[This corrects the article DOI: 10.1371/journal.pone.0152188.].