Although visual hallucinations in Parkinson's disease (PD) have been described in several major studies, little is known about olfactory hallucinations (OHs).
The authors performed a detailed ...analysis of OHs in a cohort of 87 Parkinsonian patients to estimate the prevalence of OHs and describe their phenomenology. They also evaluated smelling abilities in terms of detection and identification. Assessment of both, OHs and olfactory function, was also performed using a control group of 40 normal subjects.
Nine patients exhibited OHs compared with none of the controls, giving a prevalence of 10% for OHs in patients. OHs were described as rare, short-lasting, unpleasant odours which are not frightening since clearly identified by the patient as hallucinations. Parkinsonian patients with OHs exhibited olfactory impairment of detection and identification compared with controls, but there was no difference in their olfactory abilities from Parkinsonian patients without OHs.
In conclusion, OHs should be added to the list of non-motor PD symptoms that can occur early or late in the course of PD. The authors' study did not reveal any significant difference in terms of olfactory abilities between patients with or without OHs. However, olfactory impairment is well documented in Parkinsonian patients and cannot be totally ruled out as a risk factor for OHs. The authors recognise that complex mechanisms are probably involved in this phenomenon.
Deep brain stimulation of the subthalamic nucleus (DBS) is a widely used surgical technique to suppress motor symptoms in Parkinson’s disease (PD), and as such improves patients’ quality of life. ...However, DBS may produce emotional disorders such as a reduced ability to recognize emotional facial expressions (EFE). Previous studies have not considered the fact that DBS and l-dopa medication can have differential, common, or complementary consequences on EFE processing. A thorough way of investigating the effect of DBS and l-dopa medication in greater detail is to compare patients’ performances after surgery, with the two therapies either being administered (‘on’) or not administered (‘off’). We therefore used a four-condition (l-dopa ‘on’/DBS ‘on’, l-dopa ‘on’/DBS ‘off’, l-dopa ‘off’/DBS ‘on’, and l-dopa ‘off’/DBS ‘off’) EFE recognition paradigm and compared implanted PD patients to healthy controls. The results confirmed those of previous studies, yielding a significant impairment in the detection of some facial expressions relative to controls. Disgust recognition was impaired when patients were ‘off’ l-dopa and ‘on’ DBS, and fear recognition impaired when ‘off’ of both therapies. More interestingly, the combined effect of both DBS and l-dopa administration seems much more beneficial for EFE recognition than the separate administration of each individual therapy. We discuss the implications of these findings in the light of the inverted U curve function that describes the differential effects of dopamine level on the right orbitofrontal cortex (OFC). We propose that, while l-dopa could “overdose” in dopamine the ventral stream of the OFC, DBS would compensate for this over-activation by decreasing OFC activity, thereby restoring the necessary OFC–amygdala interaction. Another finding is that, when collapsing over all treatment conditions, PD patients recognized more neutral faces than the matched controls, a result that concurs with embodiment theories.
► We study the different emotional effect of STN-DBS and l-dopa in Parkinson’s disease. ► The administration of the two therapies simultaneously enhances emotion processing. ► l-dopa overdoses the OFC but STN DBS compensate for this by decreasing its activity.
To assess the efficacy of epidural motor cortex stimulation (MCS) on dystonia, spasticity, pain, and quality of life in patients with dystonia secondary to a focal basal ganglia (BG) lesion.
In this ...double-blind, crossover, multicenter study, 5 patients with dystonia secondary to a focal BG lesion were included. Two quadripolar leads were implanted epidurally over the primary motor (M1) and premotor cortices, contralateral to the most dystonic side. The leads were placed parallel to the central sulcus. Only the posterior lead over M1 was activated in this study. The most lateral or medial contact of the lead (depending on whether the dystonia predominated in the upper or lower limb) was selected as the anode, and the other 3 as cathodes. One month postoperatively, patients were randomly assigned to on- or off-stimulation for 3 months each, with a 1-month washout between the 2 conditions. Voltage, frequency, and pulse width were fixed at 3.8 V, 40 Hz, and 60 μs, respectively. Evaluations of dystonia (Burke-Fahn-Marsden Scale), spasticity (Ashworth score), pain intensity (visual analog scale), and quality of life (36-Item Short Form Health Survey) were performed before surgery and after each period of stimulation.
Burke-Fahn-Marsden Scale, Ashworth score, pain intensity, and quality of life were not statistically significantly modified by MCS.
Bipolar epidural MCS failed to improve any clinical feature in dystonia secondary to a focal BG lesion.
This study provides Class I evidence that bipolar epidural MCS with the anode placed over the motor representation of the most affected limb failed to improve any clinical feature in dystonia secondary to a focal BG lesion.
Purpose
Groups performing deep brain stimulation advocate post-operative imaging magnetic resonance imaging (MRI) or computer tomography (CT) to analyse the position of each electrode contact. The ...artefact of the Activa 3389 electrode had been described for MRI but not for CT. We undertook an electrode artefact analysis for CT imaging to obtain information on the artefact dimensions and related electrode contact positions.
Methods
The electrode was fixed on a phantom in a set position and six acquisitions were run (in-vitro study). The artefacts were compared with the real electrode position. Ten post-operative acquisitions were analysed (in-vivo analysis). We measured:
H
(height of the lateral black artefact),
D
(distance between the beginning of the white and the lateral black artefacts) and
W
(maximal artefact width), representing respectively the lengths of the four contacts and the electrode tip and width of the contact zone. A Student
t
-test compared the results: in vivo vs in vitro and coronal vs sagittal reconstructions along the electrode.
Results
The limits of the lateral black artefact around the electrode contacts corresponded to the final electrode position. There was no significant difference for
D
(in vivo, 1.1 ± 0.1 mm; in vitro, 1.2 ± 0.2 mm;
p
= 0.213), while
W
and
H
differed slightly (in vivo,
W
= 3.3 ± 0.2 mm,
H
= 7.7 ± 0.2 mm; in vitro,
W
= 3.1 ± 0.1 mm,
H
= 7.5 ± 0.2 mm). Results obtained with sagittal and coronal reconstructions were similar (
p
> 0.6).
Conclusions
Precise three-dimensional (3D) localisation of the four-contact zone of the electrode can be obtained by CT identification of the limits of the lateral black artefact. The relative position of the four contacts is deduced from the size of the contacts and the inter-contact distance. Sagittal and coronal reconstructions along the electrode direction should be considered for the identification of the four electrode contacts. CT offers a useful alternative to post-operative MRI.
In this article, we briefly review the concept of brain mapping in stereotactic surgery taking into account recent advances in stereotactic imaging. The gold standard continues to rely on ...probabilistic and indirect targeting, relative to a stereotactic reference, i.e., mostly the anterior (AC) and the posterior (PC) commissures. The theoretical position of a target defined on an atlas is transposed into the stereotactic space of a patient’s brain; final positioning depends on electrophysiological analysis. The method is also used to analyze final electrode or lesion position for a patient or group of patients, by projection on an atlas. Limitations are precision of definition of the AC–PC line, probabilistic location and reliability of the electrophysiological guidance. Advances in MR imaging, as from 1.5-T machines, make stereotactic references no longer mandatory and allow an anatomic mapping based on an individual patient’s brain. Direct targeting is enabled by high-quality images, an advanced anatomic knowledge and dedicated surgical software. Labeling associated with manual segmentation can help for the position analysis along non-conventional, interpolated planes. Analysis of final electrode or lesion position, for a patient or group of patients, could benefit from the concept of membership, the attribution of a weighted membership degree to a contact or a structure according to its level of involvement. In the future, more powerful MRI machines, diffusion tensor imaging, tractography and computational modeling will further the understanding of anatomy and deep brain stimulation effects.
The subthalamic nucleus (STN) is the main target for deep brain stimulation in Parkinson’s disease. We analysed the relationships between magnetic resonance imaging (MRI) anatomy and spontaneous ...neuronal activity to confirm the potential of microelectrode recordings to assist in determining the optimal surgical target. Ten bilateral surgeries were performed after 1.5‐T (T2‐weighted) anatomical MRI identification of the STN, zona incerta (ZI), Forel’s field H2 (H2) and substantia nigra (SN). Spontaneous neuronal activity was recorded simultaneously along the distal 10 mm on a central track (optimally covering the STN) and a 2‐mm anterior track. We calculated off‐line mean firing rate and burst frequency on 248 neurons clustered according to anatomical structure. Subjective visual analysis of signal was also realized on‐line, during surgery, to classify patterns of activity. Mean firing rate and burst frequency increased from H2–ZI to SN. The mean firing rate was higher in SN only using paired comparison (SN vs. its neighbours). The burst frequency was lower in H2 than in SN; using comparison with neighbours, it was lower in H2 and ZI. An irregular high activity (type 2C) was more often detected in STN and SN than in H2 and ZI. Anatomical boundaries and unitary recordings appear to be linked, supporting the ability of MRI to provide a detailed anatomy. Electrophysiological mapping combined with MRI is a useful tool for precise targeting in the subthalamic region.
Based on a variety of empirical evidence obtained within the theoretical framework of embodiment theory, we considered it likely that motor disorders in Tourette's syndrome (TS) would have emotional ...consequences for TS patients. However, previous research using emotional facial categorization tasks suggests that these consequences are limited to TS patients with obsessive-compulsive behaviors (OCB).
These studies used long stimulus presentations which allowed the participants to categorize the different emotional facial expressions (EFEs) on the basis of a perceptual analysis that might potentially hide a lack of emotional feeling for certain emotions. In order to reduce this perceptual bias, we used a rapid visual presentation procedure.
Using this new experimental method, we revealed different and surprising impairments on several EFEs in TS patients compared to matched healthy control participants. Moreover, a spatial frequency analysis of the visual signal processed by the patients suggests that these impairments may be located at a cortical level.
The current study indicates that the rapid visual presentation paradigm makes it possible to identify various potential emotional disorders that were not revealed by the standard visual presentation procedures previously reported in the literature. Moreover, the spatial frequency analysis performed in our study suggests that emotional deficit in TS might lie at the level of temporal cortical areas dedicated to the processing of HSF visual information.
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