Early Use of Erenumab vs Nonspecific Oral Migraine Preventives: The APPRAISE Randomized Clinical Trial

Importance

Patients with migraine often cycle through multiple nonspecific preventive medications due to poor tolerability and/or inadequate efficacy leading to low adherence and increased disease burden.

Objective

To compare the efficacy, tolerability, patient adherence, and patient satisfaction between erenumab and nonspecific oral migraine preventive medications (OMPMs) in patients with episodic migraine (EM) who had previously failed 1 or 2 preventive treatments.

Design, Setting, and Participants

The 12-month prospective, interventional, global, multicenter, active-controlled, randomized clinical trial comparing sustained benefit of 2 treatment paradigms (erenumab qm vs oral prophylactics) in adult episodic migraine patients (APPRAISE) trial was a 12-month open-label, multicenter, active-controlled, phase 4 randomized clinical trial conducted from May 15, 2019, to October 1, 2021. This pragmatic trial was conducted at 84 centers across 17 countries. Overall, participants 18 years or older with a 12-month or longer history of migraine, and 4 or more but fewer than 15 monthly migraine days (MMDs) were included.

Interventions

Patients were randomized (2:1) to receive erenumab or OMPMs. Dose adjustment was permitted (label dependent).

Main Outcomes and Measures

The primary end point was the proportion of patients completing 1 year of the initially assigned treatment and achieving a reduction of 50% or greater from baseline in MMDs at month 12. Secondary end points included the cumulative mean change from baseline in MMDs during the treatment period and the proportion of responders according to the Patients' Global Impression of Change (PGIC) scale at month 12 for patients taking the initially assigned treatment.

Results

A total of 866 patients were screened, of whom 245 failed the screening and 621 completed the screening and baseline period. Of the 621 randomized patients (mean [SD] age, 41.3 [11.2] years; 545 female [87.8%]; 413 [66.5%] in the erenumab group; 208 [33.5%] in the OMPM group), 523 (84.2%) completed the treatment phase, and 98 (15.8%) discontinued the study. At month 12, significantly more patients assigned to erenumab vs OMPM achieved the primary end point (232 of 413 [56.2%] vs 35 of 208 [16.8%]; odds ratio [OR], 6.48; 95% CI, 4.28-9.82; P <.001). Compared with OMPMs, treatment with erenumab showed higher responder rate (314 of 413 [76.0%] vs 39 of 208 [18.8%]; OR, 13.75; 95% CI, 9.08-20.83; P <.001) on the PGIC scale (≥5 at month 12). Significant reduction in cumulative average MMDs was reported with erenumab treatment vs OMPM treatment (-4.32 vs -2.65; treatment difference [SE]: -1.67 [0.35] days; P < .001). Substantially fewer patients in the erenumab arm compared with the OMPM arm switched medication (9 of 413 [2.2%] vs 72 of 208 [34.6%]) and discontinued treatment due to adverse events (12 of 408 [2.9%] vs 48 of 206 [23.3%]). No new safety signals were identified.

Conclusions and Relevance

Results of this randomized clinical trial demonstrated that earlier use of erenumab in patients with EM who failed 1 or 2 previous preventive treatments provided greater and sustained efficacy, safety, and adherence than continuous OMPM.

Trial Registration

ClinicalTrials.gov Identifier: NCT03927144.

Morphological Differentiation of Corneal Inflammatory Cells: Proposal of Pragmatic Protocol

PURPOSE

Corneal confocal microscopy is a noninvasive imaging technique to analyze corneal nerve fibers and corneal inflammatory cells (CICs). The amount of CICs is a potential biomarker of disease activity in chronic autoinflammatory diseases. To date, there are no standardized criteria for the morphological characterization of CICs. The aim was to establish a protocol for a standardized morphological classification of CICs based on a literature search and to test this protocol for applicability and reliability.

METHODS

A systematic review of the literature about definitions of CICs was conducted. Existing morphological descriptions were translated into a structured algorithm and applied by raters. Subsequently, the protocol was optimized by reducing and defining the criteria of the cell types. The optimized algorithm was applied by 4 raters. The interrater reliability was calculated using Fleiss kappa (K).

RESULTS

A systematic review of the literature revealed no uniform morphological criteria for the differentiation of the individual cell types in CICs. Our first protocol achieved only a low level of agreement between 3 raters (K = 0.09; 1062 rated cells). Our revised protocol was able to achieve a higher interrater reliability with 3 (K = 0.64; 471 rated cells) and 4 (K = 0.61; 628 rated cells) raters.

CONCLUSIONS

The indirect use of criteria from the literature leads to a high error rate. By clearly defining the individual cell types and standardizing the protocol, reproducible results were obtained, allowing the introduction of this protocol for the future evaluation of CICs in the corneal confocal microscopy.

Real-world evidence data on the monoclonal antibody erenumab in migraine prevention: perspectives of treating physicians in Germany

BACKGROUND

Erenumab, the first-in-class fully human monoclonal antibody targeting the calcitonin gene-related peptide receptor, was shown to be efficacious and safe for the prophylactic treatment of migraine in adults in randomized clinical trials. Large-scale, real-world evidence in multi-centre settings is still needed to confirm these results. Erenumab patient profiles outside clinical trials and physicians' treatment patterns, as well as data from patients treated in Germany, a severely impacted population, are not published yet.

METHODS

TELESCOPE was a multi-centre survey gathering real-world data from 45 German headache centres between July 2019 and December 2019. The project consisted of two parts. In the first part, treating physicians shared their experiences on current erenumab treatment with regard to patient profiles, treatment patterns and treatment responses. In the second part, a retrospective chart review was conducted of 542 migraine patients treated with erenumab for at least three months. Treatment responses focused on various aspects of patients' quality of life.

RESULTS

The analysis of 542 patients' charts revealed that three-month treatment with erenumab significantly reduced monthly headaches, migraine and acute medication days. Furthermore, headache intensity and frequency were reduced in over 75 % and accompanying aura in 35 % of patients. The clinical global impression scale revealed a general improvement in 91 % of patients. According to the treating physicians' professional judgement, 83 % of patients responded to erenumab and 80 % were satisfied with the treatment. Physicians evaluated restricted quality of life, the number of monthly migraine days and previous, prophylactic treatments as the main components of the current patient profile for monoclonal antibody recipients. Based on the assessment of physicians, erenumab reduced migraine symptoms in 65 % and increased quality of life in more than 75 % of their patients.

CONCLUSIONS

TELESCOPE confirms positive treatment responses with erenumab shown in clinical trials in a real-world multi-centre setting. The results show consistently positive experiences of physicians utilizing erenumab in clinical practice and underline that therapy with this monoclonal antibody is effective in migraine patients, particular in those, who have failed several prophylactic therapies.

Increased thalamic glutamate/glutamine levels in migraineurs

BACKGROUND

Increased cortical excitability has been hypothesized to play a critical role in various neurological disorders, such as restless legs syndrome, epilepsy and migraine. Particularly for migraine, local hyperexcitability has been reported. Levels of regional excitatory and inhibitory neurotransmitters are related to cortical excitability and hence may play a role in the origin of the disease. Consequently, a mismatch of the excitatory-inhibitory neurotransmitter network might contribute to local hyperexcitability and the onset of migraine attacks. In this study we sought to assess local levels of glutamate / glutamine (GLX) and gamma-aminobutyric acid (GABA) in the occipital cortex and right thalamus of migraineurs and healthy subjects.

METHODS

We measured interictally local biochemical concentrations in the occipital lobe and the right thalamus in patients with migraine (without aura) and healthy controls (HCs) using proton magnetic resonance spectroscopy at 3 T. GLX levels were acquired using PRESS and GABA levels using the GABA-sensitive editing sequence MEGA-PRESS. Regional GLX and GABA levels were compared between groups.

RESULTS

Statistical analyses revealed significantly increased GLX levels in both the primary occipital cortex and thalamus. However, we found no group differences in GABA levels for these two regions. Correlation analyses within the migraine group revealed no significant correlations between pain intensity and levels of GLX or GABA in either of the two brain regions.

CONCLUSIONS

Further research is needed to investigate the role of GABA/GLX ratios in greater depth and to measure changes in neurotransmitter levels over time, i.e. during migraine attacks and interictally.

Sphenopalatine ganglion stimulation for cluster headache, results from a large, open-label European registry

Background

Cluster headache (CH) is a disabling primary headache disorder characterized by severe periorbital pain. A subset of patients does not respond to established pharmacological therapy. This study examines outcomes of a cohort of mainly chronic CH patients treated with sphenopalatine ganglion (SPG) stimulation.

Methods

Patients were followed in an open-label prospective study for 12 months. Ninety-seven CH patients (88 chronic, 9 episodic) underwent trans-oral insertion of a microstimulator targeting the SPG. Patients recorded stimulation effect prospectively for individual attacks. Frequency, use of preventive and acute medications, headache impact (HIT-6) and quality of life measures (SF-36v2) were monitored at clinic visits. Per protocol, frequency responders experienced ≥ 50% reduction in attack frequency and acute responders treated ≥ 50% of attacks. HIT-6 responders experienced an improvement ≥ 2.3 units and SF-36 responders ≥ 4 units vs. baseline.

Results

Eighty-five patients (78 chronic, 7 episodic) remained implanted and were evaluated for effectiveness at 12 months. In total, 68% of all patients were responders, 55% of chronic patients were frequency responders and 32% of all patients were acute responders. 67% of patients using acute treatments were able to reduce the use of these by 52% and 74% of chronic patients were able to stop, reduce or remain off all preventive medications. 59% of all patients were HIT-6 responders, 67% were SF-36 responders.

Conclusions

This open-label registry corroborates that SPG stimulation is an effective therapy for CH patients providing therapeutic benefits and improvements in use of medication as well as headache impact and quality of life.

Electronic supplementary material

The online version of this article (10.1186/s10194-017-0828-9) contains supplementary material, which is available to authorized users.

Prospective PC-interactive Pressure Algesimetry of Post-Traumatic Neck pain after Whiplash Injury

Cervical pain is a prominent symptom in both acute whiplash injury and late whiplash syndrome. However, no systematic analysis of post-traumatic pain development covering several weeks has yet been performed in whiplash patients. It was the aim of the present study to analyse the duration and course of post-traumatic muscle pain due to whiplash injury in a prospective follow-up examination with short investigation intervals. A recovery of initially increased muscle pain after whiplash injury within 1 month was hypothesized. Pressure pain of the splenius and trapezius muscles was recorded using PC-interactive pressure algesimetry. Whiplash patients were investigated during the acute injury stage and after 3, 4, and 6 weeks and compared with matched controls. We found significantly increased pressure pain of the splenius and trapezius muscles in the acute stage of whiplash injury. After 4 weeks patients' scores of pain parameters were comparable to those of healthy control subjects. Within the patient group the first changes of pressure pain were observed within 3 (splenius) and 4 weeks (trapezius). For most patients the recovery dynamics lasted 4-6 weeks. A minority of patients did not show any improvement after 6 weeks. The present study shows that the dynamics of pressure pain due to whiplash injury can be quantified by means of PC-interactive pressure algesimetry. Our results confirm the clinical experience that the acute post-traumatic cervical syndrome normally subsides within weeks.

Quantification of Acute Neck Pain Following Whiplash Injury by Computer-Aided Pressure Algesimetry

Until now the clinical investigation of cervical pain due to whiplash injury is mainly based on finger palpation. The present study introduces a PC-interactive pressure algesimetry to standardize cervical pain measurement. Pressure pain scores of the splenius and trapezius muscles of 23 patients with an acute cervical syndrome after whiplash injury were compared to those of 24 healthy subjects. The pressure painfulness of neck and shoulder muscles was significantly increased in whiplash patients. The splenii muscles showed an equally increased muscle pain whereas the trapezii muscles showed a left-sided preponderance of painfulness, possibly due to the seat belt position in this group of motor vehicle drivers. The computer-interactive pressure algesimetry enables a standardized and rater-independent quantification of the cervical syndrome with neck and shoulder pain caused by whiplash injury.

Case report of an alleviation of pain symptoms in hypnic headache via greater occipital nerve block

Background Hypnic headache is a rare primary headache disorder with a few hundred described cases so far. Due to the fact that this headache disease is rare, there are no placebo-controlled oral medication studies. After all reported oral medication failed to control pain symptoms of a hypnic headache disease, we were able to reduce pain intensity and frequency via two greater occipital nerve (GON) blocks. Case We report on a 74-year-old patient diagnosed with hypnic headache in our headache outpatient department two years ago. Over a course of nine months none of the recommended oral drugs had an effect in pain alleviation and we decided to try an occipital nerve injection therapy. Two GON-blocks then led to a stable and significant pain reduction over the course of six months during monthly follow-ups. Conclusion GON block can be a successful therapeutic approach for the treatment of hypnic headache when oral medication fails.

A single dose of lorazepam reduces paired-pulse suppression of median nerve evoked somatosensory evoked potentials

Paired-pulse behaviour in the somatosensory cortex is an approach to obtain insights into cortical processing modes and to obtain markers of changes of cortical excitability attributable to learning or pathological states. Numerous studies have demonstrated suppression of the response to the stimulus that follows a first one after a short interval, but the underlying mechanisms remain elusive, although there is agreement that GABAergic mechanisms seem to play a crucial role. We therefore aimed to explore the influence of the GABAA agonist lorazepam on paired-pulse somatosensory evoked potentials (SEPs). We recorded and analysed SEPs after paired median nerve stimulation in healthy individuals before and after they had received a single dose of 2.5 mg of lorazepam as compared with a control group receiving placebo. Paired-pulse suppression was expressed as a ratio of the amplitudes of the second and the first peaks. We found that, after lorazepam application, paired-pulse suppression of the cortical N20 component remained unchanged, but suppression of the N20-P25 complex was significantly reduced, indicative of GABAergic involvement in intracortical processing. Our data suggest that lorazepam most likely enhances inhibition within the cortical network of interneurons responsible for creating paired-pulse suppression, leading to reduced inhibitory drive with a subsequently reduced amount of suppression. The results provide further evidence that GABAA -mediated mechanisms are involved in the generation of median nerve evoked paired-pulse suppression.

[Segmental testicular infarction. Unusual complication of intravenous immunoglobulin therapy for multifocal motor neuropathy]

We describe the previously unknown case of segmental testicular infarction as an iatrogenic complication of intravenous immunoglobulin administration in a patient with multifocal motor neuropathy.

Local anesthetic sympathectomy restores fMRI cortical maps in CRPS I after upper extremity stellate blockade: a prospective case study

BACKGROUND

Patients with complex regional pain syndrome type I (CRPS I) show a cortical reorganization with contralateral shrinkage of cortical maps in S1. The relevance of pain and disuse for the development and the maintenance of this shrinkage is unclear.

OBJECTIVE

Aim of the study was to assess whether short-term pain relief induces changes in the cortical representation of the affected hand in patients with CRPS type I.

STUDY DESIGN

Case series analysis of prospectively collected data.

METHODS

We enrolled a case series of 5 consecutive patients with CRPS type I (disease duration 3 - 36 months) of the non-dominant upper-limb and previously diagnosed sympathetically maintained pain (SMP) by reduction of the pain intensity of more than > 30% after prior diagnostic sympathetic block. We performed fMRI for analysis of the cortical representation of the affected hand immediately before as well as one hour after isolated sympathetic block of the stellate ganglion on the affected side.

STATISTICS

Wilcoxon-Test, paired t-test, P < 0.05.

RESULTS

Pain decrease after isolated sympathetic block (pain intensity on the numerical rating scale (0 - 10) before block: 6.8 ± 1.9, afterwards: 3.8 ± 1.3) was accompanied by an increase in the blood oxygenation level dependent (BOLD) response of cortical representational maps only of the affected hand which had been reduced before the block, despite the fact that clinical and neurophysiological assessment revealed no changes in the sensorimotor function.

LIMITATIONS

The interpretation of the present results is partly limited due to the small number of included patients and the missing control group with placebo injection.

CONCLUSIONS

The association between recovery of the cortical representation and pain relief supports the hypothesis that pain could be a relevant factor for changes of somatosensory cortical maps in CRPS, and that these are rapidly reversible.

Incidence and predictors of chronic headache attributed to whiplash injury

We identified clinical, demographic and psychological predictive factors that may contribute to the development of chronic headache associated with mild to moderate whiplash injury [Quebec Task Force (QTF) ≤ II] and determined the incidence of this chronic pain state. Patients were recruited prospectively from six participating accident and emergency departments. While 4.6% of patients developed chronic headache attributed to whiplash injury according to the International Classification of Headache Disorders, 2nd edn criteria, 15.2% of patients complained about headache lasting > 42 days (QTF criteria). Predictive factors were pre-existing facial pain [odds ratio (OR) 9.7, 95% confidence interval (CI) 2.1, 10.4; P = 0.017], lack of confidence to recover completely (OR 5.5, 95% CI 2.0, 13.2; P = 0.005), sore throat (OR 5.0, 95% CI 1.5, 8.9; P = 0.013), medication overuse (OR 4.2, 95% CI 1.4, 12.3; P = 0.009), high Neck Disability Index (OR 4.0, 95% CI 1.3, 12.6; P = 0.019), hopelessness/anxiety (OR 3.8, 95% CI 1.3, 8.7; P = 0.024), and depression (OR 3.3, 95% CI 1.2, 9.4; P = 0.024). The lack of a control group limits the conclusions that can be drawn from this study. Identified predictors closely resemble those found in chronic primary headache disorders.

Visual paired-pulse stimulation reveals enhanced visual cortex excitability in migraineurs

Migraine is a common ictal disorder with an interindividual heterogeneous characteristic, whose underlying mechanisms remain elusive. On the one hand migraine is associated with abnormal cortical hyperexcitability. On the other hand, studies reported lower amplitudes of visual-evoked potentials (VEPs) and concluded that low preactivation levels imply decreased excitability. Here we measured visual cortex excitability and paired-pulse suppression in subjects suffering from migraine without aura and in a group of aged- and gender-matched healthy subjects to address the relation between activation levels and excitability. To that aim, we analysed amplitudes of VEPs and paired-pulse suppression evoked by a paired-pulse stimulation paradigm using stimulus onset asynchronies (SOAs) between 80 and 133 ms. We found that in migraineurs in the interictal state the amplitudes of the first VEP were reduced as compared with healthy subjects by approximately 20%. In the case of paired-pulse suppression comparable to healthy controls, the second response amplitude should be reduced as well, which was not the case. Instead, the ratio between the first and second VEP was higher than in healthy controls and did not depend on SOA in the range tested, which demonstrates reduced paired-pulse suppression and therefore implicates increased cortical excitability. Our data show that in migraineurs VEPs were reduced presumably due to reduced activation levels. However, paired-pulse suppression using short SOAs in the range of 100 ms or less was even higher than in normal subjects. Thus, our data show that signatures of both hyper- and hypoexcitability can be found depending on stimulation condition.

Saccade induced cortical activation in patients with post-stroke visual field defects

Substantial disability in patients with hemianopia results from reduced visual perception. Several studies have shown that these patients have impaired saccades but may improve search strategies with appropriate training of saccades. We used fMRI to study the representation of saccades in patients with post-stroke hemianopia to the left. Brain activation during visually guided saccades was measured in 10 patients with a pure occipital cortical lesion causing homonymous hemianopia and in 10 healthy control subjects. Differences in activation between rest and saccades and between controls and patients were assessed with statistical parametric mapping (SPM'99). In normal subjects, significant activation was found in the frontal and parietal eye fields bilaterally and in the supplementary eye field. These areas were also activated in patients, however, to a lesser degree. In contrast, an area of increased activation in patients was found in the posterior parietal cortex of the (non-affected) left hemisphere. Visual field defects after striate lesions are associated with changes in the frontoparietal network underlying the cortical control of saccades.

G Protein β3 Polymorphism and Triptan Response in Cluster Headache

Only about 70% of migraine and cluster headache (CH) patients report significant treatment responses to triptans, which are agonists at 5-HT(1B/D) receptors belonging to the family of G protein-coupled receptors. We analyzed whether a common polymorphism in the gene for the G protein beta3 subunit (GNB3 C825T) modulates responder rates to triptans among a cohort of 231 unrelated Caucasian CH patients. A total of 180 CH patients used triptans, of whom 71.1% reported treatment success. The adjusted odds ratio for treatment response to triptans for heterozygous carriers of the GNB3 825T allele was 2.96 (95% confidence interval 1.34-6.56; P=0.0074) vs carriers of the 825CC genotype. The GNB3 genotype status did not affect responses to other acute and preventive therapeutic regimes including oxygen, verapamil, and corticosteroids, i.e., drugs not directly affecting G proteins. We conclude that pain relief by triptans is significantly modulated by a common genetic GNB3 variant.

Activity of attention related structures in multiple sclerosis patients

AIMS

It was investigated whether the cortical activity during tasks requiring focused or divided attention is reduced in multiple sclerosis patients with prominent deficits (MS(+D)) and increased in patients without impairment (MS(-D)) in these specific attention functions.

METHODS

Six MS(+D) patients with attention deficits, six unimpaired MS(-D) patients, and age-, gender-, and education-matched healthy control subjects were examined with functional magnetic resonance imaging (fMRI). The experimental paradigm consisted of visual tasks requiring focused or divided attention.

RESULTS

Performance accuracy and reaction times were impaired in MS(+D) patients. This subgroup showed reduced activation within superior and inferior frontal gyrus during focused attention. Under conditions of divided attention decreased activity was found within middle and inferior frontal gyrus, inferior parietal structures, and occipital areas. No compensatory activity was observed. MS(-D) patients did neither differ in behavioral data nor in cortical activity in attention related structures from control subjects.

CONCLUSIONS

The study found evidence for the neural correlate of attentional deficits in MS patients. In patients with specific attention deficits, reduced cortical activity in prefrontal and parietal areas, which are associated with attention and executive control, reflects the patients' reduced performance on a behavioral level. Our findings also suggest impaired top-down attentional control on sensory structures in these patients. In patients without verifiable attention deficits a normal functioning of structures relevant for executive attention was observed. Compensatory activity in these structures as a marker of reorganization in less pronounced stages of the disease was not found.

Self-initiated movements in chronic prefrontal traumatic brain injury: An event-related functional MRI study

Electrophysiological studies found traumatic lesions of the prefrontal cortex (PFC) to affect the preparation of self-initiated movements. However, a precise localization of the observed effects has not been reported yet. Moreover, previous reports did not account for effects of lesion location. Therefore, the present study utilized functional MRI to investigate the influence of predominantly left or right hemispheric PFC lesions on movement preparation in chronic traumatic brain injury (TBI) patients. 18 TBI patients with MRI-defined contusions of the PFC as well as 18 healthy control subjects matched for age and gender were examined. Patients were divided into subgroups of predominantly left or right hemispheric lesions. During functional image acquisition, subjects performed self-initiated abductions of their right index finger. Neuropsychological tests of attention and working memory, which are supposed to modulate preparatory processes, were conducted. Patients with predominantly left contusions demonstrated enhanced activity of the dorsal lateral premotor cortex in comparison to healthy control subjects. In predominantly right lesioned patients, reduced activity within the right caudate head was observed. Compared to predominantly left lesioned patients, neuropsychological tests yielded reduced task performances in the right lesion subgroup. In line with previous electrophysiological research, imaging results of the present study are interpreted to represent altered preparatory networks in chronic prefrontal TBI patients. Since attentional and working memory functions are supposed to modulate preparatory processes, differences between the patient subgroups are suggested to result from the more pronounced cognitive impairments in the right-lesioned group.

Visual cortex excitability in migraine evaluated by single and paired magnetic stimuli

OBJECTIVE

To determine the excitability of the visual cortex by phosphene thresholds (PT) in patients with migraine using transcranial magnetic stimulation (TMS) with single- and paired-pulses.

METHODS

Nineteen patients with migraine with aura (MWA), 19 patients with migraine without aura (MWoA), and 22 control subjects were included. Patients were free from preventive anti-migraine treatment and were investigated within 3 days before or after an acute migraine attack. In each subject, PT were assessed by single-pulse and paired-pulse TMS with an interstimulus interval of 50 ms.

RESULTS

The main effect of diagnosis indicated that mean PT were significantly lower in migraine patients than in control subjects (P = .001). Using single-pulse TMS, mean PT tended to be lower in MWoA-patients (57.7 +/- 11.8%) compared with control subjects (64.4 +/- 10.5%) (P = .064). In MWA-patients, mean PT (53.1 +/- 5.7%) were significantly lower compared with controls (P < .001). Using TMS with paired pulses, mean PT were significantly reduced in MWoA-patients (40.3 +/- 4.9%, P = .017) as well as in MWA-patients (39.6 +/- 4.2%, P = .005) compared with controls (44.6 +/- 6.0%). The main effect of stimulation type indicated that mean PT were lower determined with paired-pulse stimulation than with single pulses (P < .001).

CONCLUSIONS

PT are reduced in patients with migraine in the interictal state suggesting an increased excitability of visual cortical areas. Compared with single-pulse TMS, paired-pulse magnetic stimulation is more efficient to elicit phosphenes. This technique provides the opportunity to evaluate visual cortex excitability with lower stimulus intensities and less discomfort.

Kinesthesia is impaired in focal dystonia

Parkinson's disease (PD) and focal dystonia (FD) are both predominantly characterized by motor symptoms. Also, recent research has shown that sensory processing is impaired in both movement disorders. FD is characterized by involuntary movements and abnormal limb postures; thus, abnormal kinesthesia could be involved in the pathogenesis. We examined passive index finger movements in patients with FD (n = 12) and PD (n = 11) and in age-matched healthy controls (n = 13). Compared to healthy controls, patients with PD and FD were significantly impaired in the correct detection of the movement direction. The perceptual thresholds for 75% correct responses of movement direction were 0.21 degrees for FD and 0.28 degrees for PD patients compared to 0.13 degrees in control subjects. Subjects with PD and FD were also significantly impaired when they had to judge consecutive amplitudes. Results of the present study point to impaired kinesthesia in FD. Defective sensory processing could be involved in the pathophysiology of the disease and may influence dystonic contractions.

On the neural basis of focused and divided attention

Concepts of higher attention functions distinguish focused and divided attention. The present study investigated whether these mental abilities are mediated by common or distinct neural substrates. In a first experiment, 19 healthy subjects were examined with functional brain imaging (fMRI) while they attended to either one or both of two simultaneously presented visual information streams and responded to repetitive stimuli. This experiment resembled a typical examination of these mental functions with the single task demanding focused and the dual task conditions requiring divided attention. Both conditions activated a widespread, mainly right-sided network including dorso- and ventrolateral prefrontal structures, superior and inferior parietal cortex, and anterior cingulate gyrus. Under higher cognitive demands of divided attention, activity in these structures was enhanced and left-sided homologues were recruited. In a second experiment investigating another 17 subjects with almost the same paradigm, it was accounted for that in most dual task investigations of focused and divided attention the single tasks are easier to process than their combined presentation. Therefore, the task difficulty of focused attention tasks was increased. Almost the same activity pattern observed during division of attention was now found during focusing attention. Comparing both attentional states matched for task difficulty, differences were found in visual but not in prefrontal or parietal cortex areas. Our results suggest that focused and divided attention depend on largely overlapping neuronal substrates. Differences in activation patterns, especially in prefrontal and parietal areas, may result from unequal demands on executive control due to disparate processing requirements in typical tasks of focused and divided attention: Easier conditions begin with mainly right-sided activity within the attention network. As conditions become more difficult, left-lateralized homologue areas activate.

Prefrontal cortex activity in self-initiated movements is condition-specific, but not movement-related

Activity of the prefrontal cortex (PFC) has been observed in previous block-design brain imaging studies of self-initiated movements. However, the meaning of these activations remained unclear. A functional MRI experiment was carried out, which utilized an epoch and an event-related analysis approach to the data. We hypothesized that event-related activity of the PFC would argue for a contribution to movement preparation. In contrast, epoch-, but not event-related activity pointed to tonic activations, probably reflecting enhanced attentional states or working memory processing. Twenty-one subjects were examined with 845 T2*-weighted images. During active phases, subjects were instructed to perform self-initiated movements of the right index finger with intertrial intervals of about 8 s. On single subject level, epoch- and event-related regressors were entered into a combined model, estimating the exclusive contribution of either regressor. For statistical inference on multisubject level, random effects analyses were performed. For the epoch regressor, activity within the right dorso- and ventrolateral prefrontal cortex, the bilateral insula, and the right inferior parietal lobe was observed. The event-related regressor detected activity within the right inferior parietal lobe, ventral from the activity found with the epoch regressor. The present results indicate a condition-, but not a movement-related function of the PFC in self-initiated movements. Furthermore, anatomically distinct regions within the inferior parietal cortex seem to be involved in condition-specific and movement-related processes. The observed condition-specific activations are suggested to reflect attentional or working memory processes, supervising task performance, rather than movement preparation or initiation.

Reorganization of Motor Execution Rather Than Preparation in Poststroke Hemiparesis

Background and Purpose— The aim of the present study was to examine movement-related potentials (MRPs) in patients in the “chronic” stage after cortical stroke with recovered hemiparesis compared with healthy control subjects.

Methods— Right index finger MRPs were derived from 12 patients ≥1 year after infarction in the territory of the left middle cerebral artery as well as from 12 control subjects. MRP components were compared between groups.

Results— In the patient group, the component directly preceding movement onset (negative slope [NS]) was significantly reduced over the lesioned hemisphere contralateral to the movement. Furthermore, increased motor potentials (MPs) were observed over the contralesional hemisphere during movement execution. No changes in the early MRP (Bereitschaftspotential) reflecting movement preparation were found.

Conclusions— Because the NS is supposed to be generated by the primary motor cortex, the decreased component over the lesioned hemisphere is interpreted to represent impaired contralateral M1 functioning in stroke patients. Contralesional activity has been reported as a probable sign of brain plasticity by functional imaging studies. Our results broaden these findings, giving new insights into the temporal course of movement-related brain activity in recovered cortical stroke patients. The data point to a functional reorganization of motor execution rather than preparation in poststroke hemiparesis.