Altered sensorimotor integration in multiple sclerosis: A combined neurophysiological and functional MRI study.

OBJECTIVE: To explore whether abnormal thalamic resting-state functional connectivity (rsFC) contributes to altered sensorimotor integration and hand dexterity impairment in multiple sclerosis (MS). METHODS: To evaluate sensorimotor integration, we recorded kinematic features of index finger abductions during somatosensory temporal discrimination threshold (STDT) testing in 36 patients with relapsing-remitting MS and 39 healthy controls (HC). Participants underwent a multimodal 3T structural and functional MRI protocol. RESULTS: Patients had lower index finger abduction velocity during STDT testing compared to HC. Thalamic rsFC with the precentral and postcentral gyri, supplementary motor area (SMA), insula, and basal ganglia was higher in patients than HC. Intrathalamic rsFC and thalamic rsFC with caudate and insula bilaterally was lower in patients than HC. Finger movement velocity positively correlated with intrathalamic rsFC and negatively correlated with thalamic rsFC with the precentral and postcentral gyri, SMA, and putamen. CONCLUSIONS: Abnormal thalamic rsFC is a possible substrate for altered sensorimotor integration in MS, with high intrathalamic rsFC facilitating finger movements and increased thalamic rsFC with the basal ganglia and sensorimotor cortex contributing to motor performance deterioration. SIGNIFICANCE: The combined study of thalamic functional connectivity and upper limb sensorimotor integration may be useful in identifying patients who can benefit from early rehabilitation to prevent upper limb motor impairment.

Abnormal motor surround inhibition associated with cortical and deep grey matter involvement in multiple sclerosis.

OBJECTIVE: Motor surround inhibition (mSI) is a physiological mechanism that contributes to hand movement control by focusing voluntary movement. Growing evidence suggests that hand movement control is impaired in multiple sclerosis. The aim of the study was to evaluate mSI in MS and to investigate the brain structures involved in mSI in multiple sclerosis. METHODS: We recruited 33 patients and 23 controls. To investigate mSI, we delivered transcranial magnetic single pulses during index finger flexion. Motor evoked potentials were recorded and first dorsal interosseous ("active muscle") and from the abductor digiti minimi ("surround muscle"). mSI was expressed as the ratio between Motor evoked potentials recorded from the surround muscle during movement and at rest. Participants underwent a magnetic resonance study. RESULTS: Patients had impaired mSI as compared with controls. Magnetic resonance showed that basal ganglia had smaller volumes and higher mean diffusivity than controls. Impaired mSI correlated with primary motor cortex and basal ganglia involvement in multiple sclerosis. CONCLUSION: Altered mSI in multiple sclerosis is related to cortical and subcortical grey matter involvement. SIGNIFICANCE: Our study provides the first demonstration of a pathophysiological mechanism underlying hand movement control dysfunction in multiple sclerosis. mSI represents a new therapeutic target of multiple sclerosis rehabilitative approaches.

Is there evidence of bradykinesia in essential tremor?

BACKGROUND AND PURPOSE: Essential tremor (ET) is a movement disorder primarily characterized by upper limb postural and kinetic tremor. Although still under-investigated, bradykinesia may be part of the phenotypic spectrum of ET. The aim was to evaluate bradykinesia features in ET through clinical examination and kinematic analysis of repetitive finger movements. Data collected in ET patients were compared with those recorded in Parkinson's disease patients and healthy controls. METHODS: Overall, 258 subjects participated in the study (90 ET patients, 84 Parkinson's disease patients and 84 healthy controls). Repetitive finger tapping was kinematically recorded using a motion analysis system. Movement velocity, amplitude and decrement (sequence effect) were measured. The three groups were first compared by one-way analysis of variance. A cluster analysis was also performed to better address the data variability observed in ET patients. Possible relationships between kinematic and clinical data were assessed in ET patients. RESULTS: Essential tremor patients were slower than healthy controls. Movement slowness in ET did not correlate with postural or kinetic tremor severity. It was also found that movement slowness in ET was not associated with a sequence effect, which instead is a common feature in Parkinson's disease. Cluster analysis showed that a proportion of ET patients may have movement abnormalities similar to those observed in Parkinson's disease. CONCLUSIONS: Movement slowness without sequence effect is a common feature in ET patients. The present findings are relevant when interpreted in the context of the new tremor classification system and in the development of a more accurate bradykinesia definition.

Corticobasal syndrome: neuroimaging and neurophysiological advances.

Corticobasal degeneration (CBD) is a neurodegenerative condition characterized by 4R tau protein deposition in several brain regions that clinically manifests itself as a heterogeneous atypical parkinsonism typically expressed in adulthood. The prototypical clinical phenotype of CBD is corticobasal syndrome (CBS). Important insights into the pathophysiological mechanisms underlying motor and higher cortical symptoms in CBS have been gained by using advanced neuroimaging and neurophysiological techniques. Structural and functional neuroimaging studies often show asymmetric cortical and subcortical abnormalities, mainly involving perirolandic and parietal regions and basal ganglia structures. Neurophysiological investigations including electroencephalography and somatosensory evoked potentials provide useful information on the origin of myoclonus and on cortical sensory loss. Transcranial magnetic stimulation demonstrates heterogeneous and asymmetric changes in the excitability and plasticity of primary motor cortex and abnormal hemispheric connectivity. Neuroimaging and neurophysiological abnormalities in multiple brain areas reflect asymmetric neurodegeneration, leading to asymmetric motor and higher cortical symptoms in CBS.

Tremor in motor neuron disease may be central rather than peripheral in origin.

BACKGROUND AND PURPOSE: Motor neuron disease (MND) refers to a spectrum of degenerative diseases affecting motor neurons. Recent clinical and post-mortem observations have revealed considerable variability in the phenotype. Rhythmic involuntary oscillations of the hands during action, resembling tremor, can occur in MND, but their pathophysiology has not yet been investigated. METHODS: A total of 120 consecutive patients with MND were screened for tremor. Twelve patients with action tremor and no other movement disorders were found. Ten took part in the study. Tremor was recorded bilaterally using surface electromyography (EMG) and triaxial accelerometer, with and without a variable weight load. Power spectra of rectified EMG and accelerometric signal were calculated. To investigate a possible cerebellar involvement, eyeblink classic conditioning was performed in five patients. RESULTS: Action tremor was present in about 10% of our population. All patients showed distal postural tremor of low amplitude and constant frequency, bilateral with a small degree of asymmetry. Two also showed simple kinetic tremor. A peak at the EMG and accelerometric recordings ranging from 4 to 12 Hz was found in all patients. Loading did not change peak frequency in either the electromyographic or accelerometric power spectra. Compared with healthy volunteers, patients had a smaller number of conditioned responses during eyeblink classic conditioning. CONCLUSIONS: Our data suggest that patients with MND can present with action tremor of a central origin, possibly due to a cerebellar dysfunction. This evidence supports the novel idea of MND as a multisystem neurodegenerative disease and that action tremor can be part of this condition.

Disease progression in blepharospasm: a 5-year longitudinal study.

BACKGROUND AND PURPOSE: The clinical manifestation of dystonic spasms in blepharospasm (BSP) patients may be heterogeneous. Whether the varying phenomenology of eyelid spasms becomes manifest sequentially during the course of the disease or aggregates in separate clusters according to different disease courses is still unclear. For this purpose, the clinical features in BSP patients were evaluated longitudinally over a 5-year period and also the blink reflex recovery cycle was tested in a subgroup of BSP patients. METHODS: Sixty BSP patients were videotaped at time 0 and after approximately 5 years of follow-up. Two experts in movement disorders, who were blinded to the video order, reviewed the videotapes and scored the severity of BSP using the Blepharospasm Severity Rating Scale. Changes in the R2 recovery index were also evaluated in 18 patients twice, i.e. upon enrolment and at the follow-up. RESULTS: The severity of BSP worsened significantly over the 5-year follow-up period owing to the appearance or the increased duration and frequency of prolonged spasms. It was also found that the blink reflex recovery cycle worsened at follow-up in comparison with the baseline. CONCLUSIONS: This study shows that the disease progression of BSP is characterized by the appearance or worsening of prolonged spasms. Prolonged spasms are accompanied by changes in the excitability of brainstem interneurons. Aging-related effects may exacerbate the pathophysiological mechanisms underlying spasms.

Spread of dystonia in patients with idiopathic adult-onset laryngeal dystonia.

BACKGROUND AND PURPOSE: Adult-onset laryngeal dystonia (LD) can be isolated or can be associated with dystonia in other body parts. Combined forms can be segmental at the onset or can result from dystonia spread to or from the larynx. The aim of this study was to identify the main clinical and demographic features of adult-onset idiopathic LD in an Italian population with special focus on dystonia spread. METHODS: Data were obtained from the Italian Dystonia Registry (IDR) produced by 37 Italian institutions. Clinical and demographic data of 71 patients with idiopathic adult-onset LD were extracted from a pool of 1131 subjects included in the IDR. RESULTS: Fifty of 71 patients presented a laryngeal focal onset; the remaining subjects had onset in other body regions and later laryngeal spread. The two groups did not show significant differences of demographic features. 32% of patients with laryngeal onset reported spread to contiguous body regions afterwards and in most cases (12 of 16 subjects) dystonia started to spread within 1 year from the onset. LD patients who remained focal and those who had dystonia spread did not show other differences. CONCLUSIONS: Data from IDR show that dystonic patients with focal laryngeal onset will present spread in almost one-third of cases. Spread from the larynx occurs early and is directed to contiguous body regions showing similarities with clinical progression of blepharospasm. This study gives a new accurate description of LD phenomenology that may contribute to improving the comprehension of dystonia pathophysiology.

Correction to: The Italian Dystonia Registry: rationale, design and preliminary findings.

In the original article, Gina Ferrazzano was affiliated to Department of Neurology and Psychiatry, Neuromed Institute IRCCS, Sapienza University of Rome, Pozzilli, Italy.The corrected affiliation should be: Neuromed Institute IRCCS, Pozzilli, IS, Italy.

Re-emergent tremor in Parkinson's disease: the effect of dopaminergic treatment.

BACKGROUND AND PURPOSE: Patients with Parkinson's disease (PD) with resting tremor may be affected by a tremor that appears after a varying latency while a posture is maintained, a phenomenon referred to as re-emergent tremor (RET). The aim of the study was to evaluate the occurrence and clinical features of RET in patients with PD tested off and on treatment, and to compare the effect of dopaminergic treatment on RET with the effect on resting and action tremor. METHODS: We consecutively enrolled 100 patients with PD. Patients were clinically evaluated 24 h after withdrawal of therapy (off-treatment phase) and 60 min after therapy administration (on-treatment phase). We collected the demographic and clinical data of patients with PD. The severity of the disease was assessed by means of the Hoehn and Yahr scale and Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale part III. We evaluated the latency, severity and body side affected both off and on treatment in patients with RET. RESULTS: Re-emergent tremor was present in 24% of the patients with PD off treatment and in 19% of the patients on treatment. Dopaminergic treatment reduced the clinical severity of RET. Dopaminergic treatment increased the number of patients with unilateral RET and reduced the number of those who had bilateral RET. RET and resting tremor responded similarly to dopaminergic treatment, whereas action tremor was less responsive. Patients with RET had milder motor symptoms than patients without RET both off and on treatment. CONCLUSIONS: Dopaminergic treatment modified RET occurrence, severity and body distribution. Dopaminergic depletion plays a role in the pathophysiology of RET.

Pain in Parkinson's disease: facts and uncertainties.

Pain is one of the most common and troublesome non-motor symptoms of Parkinson's disease (PD). It can appear at any time during the disease and is often present before diagnosis. However, there is little or no consensus on its definition. An expert group of clinicians with relevant research experience met to review the existing evidence and to identify gaps in our understanding leading towards AUTHOR: 'understanding towards' has been changed to 'understanding leading towards'. Please check and confirm that this is appropriate an optimized therapy of pain in PD. Key findings from epidemiologic, neurophysiologic, neuroimaging and clinical studies are reviewed. In each case, the evidence base is limited by wide variations in the definitions of pain applied, study methodologies and populations evaluated. Disease-related and medical conditions trigger spontaneous pain in patients with PD, which is then abnormally processed and results in painful manifestations in specific body parts. Dopaminergic medications, such as rotigotine, as well as opiate analgesics, such as oxycodone, have shown positive results but future studies with more detailed pain characterization at inclusion are warranted.

Relationship between pain and motor and non-motor symptoms in Parkinson's disease.

BACKGROUND AND PURPOSE: Although female gender, depressive symptoms and medical conditions predisposing to pain are more common in patients with Parkinson's disease (PD) with pain, no study has yet explored the relationship between pain and other non-motor symptoms (NMS). METHODS: A total of 321 consecutive patients with PD [190 men/131 women aged 68.3 (SD 9.2) years] attending four Italian movement disorder clinics were studied. Demographic/clinical data were obtained by a standardized interview and the NMS scale. The association of pain with motor and NMS was assessed by multivariable logistic regression models. RESULTS: At the time of the study, 180 patients with PD (56%) reported chronic pain that, in most cases, was described as being muscular or arthralgic pain. Pain preceded the onset of motor signs in 36/180 patients. In the main-effect model, factors independently associated with pain were female sex [odds ratio (OR), 2.1; P = 0.01], medical conditions predisposing to pain (OR, 2.9; P < 0.001), Hoehn-Yahr staging (OR, 1.9; P = 0.04), motor complications (OR, 4.7; P = 0.04) and NMS belonging to the sleep/fatigue (OR, 1.6; P = 0.04) and mood/cognition (OR, 1.6; P = 0.03) domains. Most explanatory variables in the multivariable analysis were similarly distributed in patients in whom pain may have been related to PD or to a cause other than PD. CONCLUSIONS: We confirm that pain in PD is more frequent in women and in subjects with medical conditions predisposing to painful symptoms. Moreover, this strengthens the association between pain and motor severity measures and NMS domains, particularly sleep and mood disturbances.

Pain-motor integration in the primary motor cortex in Parkinson's disease.

BACKGROUND: In Parkinson's disease (PD), the influence of chronic pain on motor features has never been investigated. We have recently designed a technique that combines nociceptive system activation by laser stimuli and primary motor cortex (M1) activation through transcranial magnetic stimulation (TMS), in a laser-paired associative stimulation design (Laser-PAS). In controls, Laser-PAS induces long-term changes in motor evoked potentials reflecting M1 long-term potentiation-like plasticity, arising from pain-motor integration. OBJECTIVE: We here examined the possible influence of chronic pain on motor responses to Laser-PAS in patients with PD, with and without chronic pain. METHODS: We compared motor responses to Laser-PAS in healthy subjects and in patients with PD, with and without chronic pain. RESULTS: Unlike controls, we found reduced responses to Laser-PAS in patients with PD, with and without pain. Patients off and on dopaminergic therapy had similar responses to Laser-PAS. When comparing responses to Laser-PAS in patients with and without pain, the two patients' subgroups had similar abnormalities. When we compared patients with pain in the body region investigated with Laser-PAS, with those with pain in other body regions, we found prominent changes in patients with homotopic pain. Finally, when comparing Laser-PAS with the original PAS protocol, which combines electric peripheral nerve stimuli and TMS, in patients without pain and those with homotopic pain, we found similar responses to both techniques in patients without pain, whereas Laser-PAS induced greater abnormalities than PAS in patients with pain. CONCLUSIONS: In PD, chronic pain degrades response to Laser-PAS through abnormal pain-motor integration.

Clinical heterogeneity in patients with idiopathic blepharospasm: A cluster analysis.

BACKGROUND: Idiopathic blepharospasm is a clinically heterogeneous condition. It is not known whether the various manifestations become manifest sequentially during the course of the disease or aggregate in separate clusters identifying subpopulations of patients. METHODS: Eighty-nine patients with idiopathic blepharospasm were assessed using k-means cluster analysis to identify relatively homogeneous groups on the basis of low-intragroup/high-intergroup differences across a set of selected variables. RESULTS: The results suggest that there may be three groups of patients. Group 1 included patients who had prolonged muscle spasms leading to complete rim closure associated with brief and/or prolonged spasms with incomplete rim closure, the most severe blepharospasm, and a greater tendency to spread to adjacent segments. Group 2 included patients characterized by prolonged spasms with partial rim closure, either alone or associated with brief spasms whereas Group 3 included patients with brief spasms with complete rim closure, the least severe blepharospasm, and the lowest tendency to spread. The severity of Group 2 blepharospasm was between that observed in Group 1 and Group 3, while the tendency to spread was similar to Group 3. The three groups did not differ for disease duration, age of onset, sex and other clinical features. The observation that inhibition of the R2 component of the blink reflex recovery cycle was more abnormal in Groups 1/2 2 than in Group 3 at least in part validates our classification. CONCLUSIONS: The present study suggests that blepharospasm patients may be classified in different subtypes according to the type of spasms, severity of the condition and tendency to spread.

The Italian Dystonia Registry: rationale, design and preliminary findings.

The Italian Dystonia Registry is a multicenter data collection system that will prospectively assess the phenomenology and natural history of adult-onset dystonia and will serve as a basis for future etiological, pathophysiological and therapeutic studies. In the first 6 months of activity, 20 movement disorders Italian centres have adhered to the registry and 664 patients have been recruited. Baseline historical information from this cohort provides the first general overview of adult-onset dystonia in Italy. The cohort was characterized by a lower education level than the Italian population, and most patients were employed as artisans, builders, farmers, or unskilled workers. The clinical features of our sample confirmed the peculiar characteristics of adult-onset dystonia, i.e. gender preference, peak age at onset in the sixth decade, predominance of cervical dystonia and blepharospasm over the other focal dystonias, and a tendency to spread to adjacent body parts, The sample also confirmed the association between eye symptoms and blepharospasm, whereas no clear association emerged between extracranial injury and dystonia in a body site. Adult-onset dystonia patients and the Italian population shared similar burden of arterial hypertension, type 2 diabetes, coronary heart disease, dyslipidemia, and hypothyroidism, while hyperthyroidism was more frequent in the dystonia population. Geographic stratification of the study population yielded no major difference in the most clinical and phenomenological features of dystonia. Analysis of baseline information from recruited patients indicates that the Italian Dystonia Registry may be a useful tool to capture the real world clinical practice of physicians that visit dystonia patients.

BDNF and LTP-/LTD-like plasticity of the primary motor cortex in Gilles de la Tourette syndrome.

Gilles de la Tourette syndrome (GTS) is characterized by motor and vocal tics and often associated with obsessive-compulsive disorder (OCD). Responses to intermittent/continuous theta-burst stimulation (iTBS/cTBS), which probe long-term potentiation (LTP)-/depression (LTD)-like plasticity in the primary motor cortex (M1), are reduced in GTS. ITBS-/cTBS-induced M1 plasticity can be affected by brain-derived neurotrophic factor (BDNF) polymorphism. We investigated whether the BDNF polymorphism influences iTBS-/cTBS-induced LTP-/LTD-like M1 plasticity in 50 GTS patients and in 50 age- and sex-matched healthy subjects. In GTS patients, motor and psychiatric (OCD) symptom severity was rated using the Yale Global Tic Severity Scale (YGTSS) and the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). We compared M1 iTBS-/cTBS-induced plasticity in healthy subjects and in patients with GTS. We also compared responses to TBS according to BDNF polymorphism (Val/Val vs Met carriers) in patients and controls. Fourteen healthy subjects and 13 GTS patients were Met carriers. When considering the whole group of controls, as expected, iTBS increased whereas cTBS decreased MEPs. Differently, iTBS/cTBS failed to induce LTP-/LTD-like plasticity in patients with GTS. When comparing responses to TBS according to BDNF polymorphism, in healthy subjects, Met carriers showed reduced MEP changes compared with Val/Val individuals. Conversely, in patients with GTS, responses to iTBS/cTBS were comparable in Val/Val individuals and Met carriers. YGTSS and Y-BOCS scores were comparable in Met carriers and in Val/Val subjects. We conclude that iTBS and cTBS failed to induce LTP-/LTD-like plasticity in patients with GTS, and this was not affected by BDNF genotype.

Impaired eye blink classical conditioning distinguishes dystonic patients with and without tremor.

INTRODUCTION: Tremor is frequently associated with dystonia, but its pathophysiology is still unclear. Dysfunctions of cerebellar circuits are known to play a role in the pathophysiology of action-induced tremors, and cerebellar impairment has frequently been associated to dystonia. However, a link between dystonic tremor and cerebellar abnormalities has not been demonstrated so far. METHODS: Twenty-five patients with idiopathic isolated cervical dystonia, with and without tremor, were enrolled. We studied the excitability of inhibitory circuits in the brainstem by measuring the R2 blink reflex recovery cycle (BRC) and implicit learning mediated by the cerebellum by means of eyeblink classical conditioning (EBCC). Results were compared with those obtained in a group of age-matched healthy subjects (HS). RESULTS: Statistical analysis did not disclose any significant clinical differences among dystonic patients with and without tremor. Patients with dystonia (regardless of the presence of tremor) showed decreased inhibition of R2 blink reflex by conditioning pulses compared with HS. Patients with dystonic tremor showed a decreased number of conditioned responses in the EBCC paradigm compared to HS and dystonic patients without tremor. CONCLUSION: The present data show that cerebellar impairment segregates with the presence of tremor in patients with dystonia, suggesting that the cerebellum might have a role in the occurrence of dystonic tremor.