M Hallett

Publications of M Hallett

• Clinical features of patients with blepharospasm: a report of 240 patients.

  Authors: E L Peckham, G Lopez, E A Shamim, S Pirio Richardson, S Sanku, R Malkani, M Stacy, P Mahant, A Crawley, A Singleton, M Hallett

  European journal of neurology : the official journal of the European Federation of Neurological Societies. 03/2011; 18(3):382-6.

  To characterize patients with benign essential blepharospasm (BEB) by diagnosis, environmental risk factors, and family history. Two hundred and forty patients with BEB were evaluated through aTo characterize patients with benign essential blepharospasm (BEB) by diagnosis, environmental risk factors, and family history. Two hundred and forty patients with BEB were evaluated through a clinical examination and questionnaire. The questionnaire reviewed personal medical history, demographic factors, risk factors for the development of blepharospasm and family history of dystonia and other neurological conditions. Benign essential blepharospasm was more commonly found in women (2.8:1) and 93% of the patients were Caucasian. Fifty percent had pure BEB, 31% had BEB/Meige's syndrome, and 4% had BEB and eyelid opening apraxia (+/- Meige's syndrome). A minority of patients reported preceding photophobia (25%) or other eye conditions (22%). The majority were non-smokers, had no exposure to anti-emetic or antipsychotic agents, had a normal birth history, and had no history of head trauma. Seventy-two percent did report a stressful event immediately prior to the development of symptoms. Treatments reported included botulinum toxin (BoNT), oral medications, surgical procedures, and acupuncture. Thirty-two percent of patients reported a family history of focal dystonia, and BEB was the most commonly reported. This study confirms previous reports of usual age, sex, caffeine and tobacco use, and family history in patients with blepharospasm. New findings include a report on occupation, lower reports of preceding eye conditions and photophobia, and higher reported stressful events. Further, this study shows a change in treatment with an increase in BoNT use and decrease in surgical procedures.

• Surround inhibition is modulated by task difficulty.

  Authors: S Beck, M Hallett

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 11/2009;

  OBJECTIVE: The aim of this study was to further characterize surround inhibition (SI) in the primary motor cortex (M1) by comparing its magnitude and time course during a simple reaction time taskOBJECTIVE: The aim of this study was to further characterize surround inhibition (SI) in the primary motor cortex (M1) by comparing its magnitude and time course during a simple reaction time task (SRT) and a choice reaction time task (CRT). METHODS: In both the SRT and the CRT, subjects performed the same right index finger flexion in response to an acoustic signal. For CRT, the alternative choice was a similar movement using the left index finger, as distinguished by a different tone. In both tasks, single pulse transcranial magnetic stimulation (TMS) was applied at rest, 75ms (T1) and 25ms before EMG onset (T2), and during the first peak of EMG (T3) in the right first dorsal interosseous muscle (FDI). Motor evoked potentials (MEPs) were recorded from both FDIs, which act as synergists in the task, and the right surrounding, relaxed abductor pollicis brevis muscle (APB). RESULTS: For right hand movement, SI started earlier and was more pronounced for CRT compared to SRT. For left hand movement in the CRT, SI was similar to that of right hand movement. CONCLUSIONS: We conclude that SI occurs earlier and stronger with increasing task difficulty. SIGNIFICANCE: The timing as well as the bilateral effect of the inhibition suggests that motor areas involved in motor planning, proximate to the motor cortex, contribute to the genesis of surround inhibition.

• Slow pre-movement cortical potentials do not reflect individual response to therapy in writer's cramp.

  Authors: K E Zeuner, M Peller, A Knutzen, S Groppa, I Holler, F Kopper, J Raethjen, D Dressler, M Hallett, G Deuschl, H R Siebner

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 06/2009;

  OBJECTIVE: To investigate whether movement-related cortical potentials (MRCP) provide a physiological correlate that indicates the response to treatment in patients with writer's cramp. METHODS: InOBJECTIVE: To investigate whether movement-related cortical potentials (MRCP) provide a physiological correlate that indicates the response to treatment in patients with writer's cramp. METHODS: In 21 patients with writer's cramp, who underwent 4weeks of limb immobilization followed by re-training for 8weeks, we recorded MRCPs preceding a self-initiated brisk finger abduction movement. MRCP measurements of pre-movement activity were performed at baseline, after the end of immobilization and four and 8weeks of re-training. We examined 12 controls, who received no intervention, twice 4weeks apart. RESULTS: Patients benefited from the therapeutical intervention (Zeuner et al., 2008). They showed no abnormalities of the MRCPs at baseline. In controls, MRCPs did not significantly change after 4weeks. In patients, immobilization and re-training had no effect on MRCPs. There was no correlation between the severity of dystonic symptoms or the individual treatment response and MRCPs. CONCLUSION: MRCPs are stable measures for interventional studies. However, they do not reflect clinical severity of dystonic symptoms or improvement after therapeutic interventions. SIGNIFICANCE: This is the first study to investigate MRCPs in a large cohort of patients with writer's cramp compared to a control group at different time points. These potentials do not reflect the motor control disorder in patients with writer's cramp.

• Inter-hemispheric inhibition is impaired in mirror dystonia.

  Authors: S Beck, E A Shamim, S Pirio Richardson, M Schubert, M Hallett

  The European journal of neuroscience. 05/2009; 29(8):1634-40.

  Surround inhibition, a neural mechanism relevant for skilled motor behavior, has been shown to be deficient in the affected primary motor cortex (M1) in patients with focal hand dystonia (FHD). EvenSurround inhibition, a neural mechanism relevant for skilled motor behavior, has been shown to be deficient in the affected primary motor cortex (M1) in patients with focal hand dystonia (FHD). Even in unilateral FHD, however, electrophysiological and neuroimaging studies have provided evidence for bilateral M1 abnormalities. Clinically, the presence of mirror dystonia, dystonic posturing when the opposite hand is moved, also suggests abnormal interhemispheric interaction. To assess whether a loss of inter-hemispheric inhibition (IHI) may contribute to the reduced surround inhibition, IHI towards the affected or dominant M1 was examined in 13 patients with FHD (seven patients with and six patients without mirror dystonia, all affected on the right hand) and 12 right-handed, age-matched healthy controls (CON group). IHI was tested at rest and during three different phases of a right index finger movement in a synergistic, as well as in a neighboring, relaxed muscle. There was a trend for a selective loss of IHI between the homologous surrounding muscles in the phase 50 ms before electromyogram onset in patients with FHD. Post hoc analysis revealed that this effect was due to a loss of IHI in the patients with FHD with mirror dystonia, while patients without mirror dystonia did not show any difference in IHI modulation compared with healthy controls. We conclude that mirror dystonia may be due to impaired IHI towards neighboring muscles before movement onset. However, IHI does not seem to play a major role in the general pathophysiology of FHD.

• Gesture Subtype-Dependent Left Lateralization of Praxis Planning: An Event-Related fMRI Study.

  Authors: S Bohlhalter, N Hattori, L Wheaton, E Fridman, E A Shamim, G Garraux, M Hallett

  Cerebral cortex (New York, N.Y. : 1991). 10/2008;

  Ideomotor apraxia is a disorder mainly of praxis planning, and the deficit is typically more evident in pantomiming transitive (tool related) than intransitive (communicative) gestures. The goal ofIdeomotor apraxia is a disorder mainly of praxis planning, and the deficit is typically more evident in pantomiming transitive (tool related) than intransitive (communicative) gestures. The goal of the present study was to assess differential hemispheric lateralization of praxis production using event-related functional magnetic resonance imaging. Voxel-based analysis demonstrated significant activations in posterior parietal cortex (PPC) and premotor cortex (PMC) association areas, which were predominantly left hemispheric, regardless of whether planning occurred for right or left hand transitive or intransitive pantomimes. Furthermore, region of interest-based calculation of mean laterality index (LI) revealed a significantly stronger left lateralization in PPC/PMC clusters for planning intransitive (LI = -0.49 + 0.10, mean + standard deviation [SD]) than transitive gestures (-0.37 + 0.08, P = 0.02, paired t-tests) irrespective of the hand involved. This differential left lateralization for planning remained significant in PMC (LI = -0.47 + 0.14 and -0.36 + 0.13, mean + SD, P = 0.04), but not in PPC (-0.56 + 0.11 and -0.45 + 0.12, P = 0.11), when both regions were analyzed separately. In conclusion, the findings point to a left-hemispheric specialization for praxis planning, being more pronounced for intransitive gestures in PMC, possibly due to their communicative nature.

• Neurocirculatory and nigrostriatal abnormalities in Parkinson disease from LRRK2 mutation.

  Authors: D S Goldstein, R Imrich, E Peckham, C Holmes, G Lopez, C. Crews, J Hardy, A Singleton, M Hallett

  Neurology. 11/2007; 69(16):1580-4.

  BACKGROUND: Patients with Parkinson disease (PD) often have cardiac sympathetic denervation and failure of neurocirculatory regulation by baroreflexes. Familial PD caused by mutation of the geneBACKGROUND: Patients with Parkinson disease (PD) often have cardiac sympathetic denervation and failure of neurocirculatory regulation by baroreflexes. Familial PD caused by mutation of the gene encoding alpha-synuclein or by alpha-synuclein gene triplication also features cardiac sympathetic denervation and baroreflex failure. METHODS: Here we report results of cardiac sympathetic neuroimaging by 6-[(18)F]fluorodopamine PET, baroreflex testing based on beat-to-beat hemodynamic responses to the Valsalva maneuver, and nigrostriatal neuroimaging using 6-[(18)F] fluorodopa PET in a proband with mutation of the gene encoding leucine-rich repeat kinase 2 (LRRK2), the most common genetic abnormality identified so far in familial PD. RESULTS: The patient had no detectable 6-[(18)F] fluorodopamine-derived radioactivity in the left ventricular myocardium, a progressive fall in blood pressure during the Valsalva maneuver and no pressure overshoot after release of the maneuver, and decreased 6-[(18)F] fluorodopa-derived radioactivity bilaterally in the putamen and substantia nigra. CONCLUSION: This patient with Parkinson disease (PD) caused by LRRK2 mutation had evidence of cardiac sympathetic denervation, baroreflex-sympathoneural and baroreflex-cardiovagal failure, and nigrostriatal dopamine deficiency, a pattern resembling that in the sporadic disease. The results fit with the concept that in LRRK2 PD, parkinsonism, cardiac sympathetic denervation, and baroreflex failure can result from a common pathogenetic process.

• Safety study of high-frequency transcranial magnetic stimulation in patients with chronic stroke.

  Authors: M P Lomarev, D Y Kim, S Pirio Richardson, B Voller, M Hallett

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 10/2007; 118(9):2072-5.

  OBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) is a potential therapeutic tool to rehabilitate chronic stroke patients. In this study, the safety of high-frequency rTMS in stroke wasOBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) is a potential therapeutic tool to rehabilitate chronic stroke patients. In this study, the safety of high-frequency rTMS in stroke was investigated (Phase I). METHODS: The safety of 20 and 25 Hz rTMS over the motor cortex (MC) of the affected hemisphere, with intensities of 110-130% of the motor threshold (MT), was evaluated using surface electromyography (EMG) of hand and arm muscles. RESULTS: Brief EMG bursts, possibly representing peripheral manifestations of after discharges, and spread of excitation to proximal muscles are considered to be associated with a high risk of seizure occurrence. These events were recorded after the rTMS trains. Neither increased MC excitability nor improved pinch force dynamometry was found after rTMS. CONCLUSIONS: Stimulation parameters for rTMS, which are safe for healthy volunteers, may lead to a higher risk for seizure occurrence in chronic stroke patients. SIGNIFICANCE: rTMS at rates of 20 and 25 Hz using above threshold stimulation potentially increases the risk of seizures in patients with chronic stroke.

• Neuroimaging of neuronal circuits involved in tic generation in patients with Tourette syndrome.

  Authors: A Lerner, A Bagic, E A Boudreau, T Hanakawa, F Pagan, Z Mari, W Bara-Jimenez, M Aksu, G Garraux, J M Simmons, S Sato, D L Murphy, M Hallett

  Neurology. 07/2007; 68(23):1979-87.

  OBJECTIVE: To identify brain regions generating tics in patients with Tourette syndrome using sleep as a baseline. METHODS: We used [15O]H2O PET to study nine patients with Tourette syndrome and nineOBJECTIVE: To identify brain regions generating tics in patients with Tourette syndrome using sleep as a baseline. METHODS: We used [15O]H2O PET to study nine patients with Tourette syndrome and nine matched control subjects. For patients, conditions included tic release states and sleep stage 2; and for control subjects, rest states and sleep stage 2. RESULTS: Our study showed robust activation of cerebellum, insula, thalamus, and putamen during tic release. CONCLUSION: The network of structures involved in tics includes the activated regions and motor cortex. The prominent involvement of cerebellum and insula suggest their involvement in tic initiation and execution.

• The basal ganglia are hyperactive during the discrimination of tactile stimuli in writer's cramp.

  Authors: M Peller, K E Zeuner, A Munchau, A Quartarone, M Weiss, A Knutzen, M Hallett, G Deuschl, H R Siebner

  Brain : a journal of neurology. 11/2006; 129(Pt 10):2697-708.

  Writer's cramp is a focal hand dystonia that specifically affects handwriting. Though writer's cramp has been attributed to a dysfunction of the basal ganglia, the role of the basal ganglia in theWriter's cramp is a focal hand dystonia that specifically affects handwriting. Though writer's cramp has been attributed to a dysfunction of the basal ganglia, the role of the basal ganglia in the pathogenesis of writer's cramp remains to be determined. Seventeen patients with writer's cramp (nine females; age range: 24-71 years) and 17 healthy individuals (six females; age range: 27-68 years) underwent functional MRI (fMRI) while they discriminated the orientation of gratings delivered to the tip of the right index finger. Statistical parametric mapping was used to analyse the fMRI data. The significance level was set at a corrected P-value of 0.05. Relative to healthy controls, patients with writer's cramp showed a widespread bilateral increase in task-related activity in the putamen, caudate nucleus, internal globus pallidus and lateral thalamus. In these areas, hyperactivity was more pronounced in patients who had recently developed writer's cramp. The enhanced response of the basal ganglia to tactile input from the affected hand is compatible with the concept of impaired centre-surround inhibition within the basal ganglia-thalamic circuit and may lead to an excessive activation of sensorimotor cortical areas during skilled movements affected by dystonia. Outside the basal ganglia, dystonic patients showed task-related overactivity in visual cortical areas, left anterior insula and right intraparietal sulcus, but not in the primary or secondary sensory cortex. In addition, task-related activity in the cerebellar nuclei, posterior vermis, right paramedian cerebellar hemisphere and dorsal pons was inversely related with the severity of hand dystonia. Regional activity in these areas may reflect secondary adaptive reorganization at the systems level to compensate for the dysfunction in the basal ganglia-thalamic loop.

• Neural correlates of tic generation in Tourette syndrome: an event-related functional MRI study.

  Authors: S Bohlhalter, A Goldfine, S Matteson, G Garraux, T Hanakawa, K Kansaku, R Wurzman, M Hallett

  Brain : a journal of neurology. 08/2006; 129(Pt 8):2029-37.

  Little is known about the neural correlates of tics and associated urges. In the present study, we aimed to explore the neural basis of tics in patients with Tourette syndrome by using event-relatedLittle is known about the neural correlates of tics and associated urges. In the present study, we aimed to explore the neural basis of tics in patients with Tourette syndrome by using event-related functional MRI (fMRI). Ten patients (6 women, 4 men; age: mean +/- SD = 31 +/- 11.2) were studied while spontaneously exhibiting a variety of motor and vocal tics. On the basis of synchronized video/audio recordings, fMRI activities were analysed 2 s before and at tic onset irrespective of the clinical phenomenology. We identified a brain network of paralimbic areas such as anterior cingulate and insular cortex, supplementary motor area (SMA) and parietal operculum (PO) predominantly activated before tic onset (P < 0.05, corrected for multiple comparisons). In contrast, at the beginning of tic action, significant fMRI activities were found in sensorimotor areas including superior parietal lobule bilaterally and cerebellum. The results of this study indicate that paralimbic and sensory association areas are critically implicated in tic generation, similar to movements triggered internally by unpleasant sensations, as has been shown for pain or itching.

• A variant in the HS1-BP3 gene is associated with familial essential tremor.

  Authors: A Shatunov, J Jankovic, R Elble, N Sambuughin, A Singleton, M Hallett, L Goldfarb

  Neurology. 01/2006; 65(12):1995; author reply 1995.

• Small de novo duplication in the repeat region of the TATA-box-binding protein gene manifest with a phenotype similar to variant Creutzfeldt-Jakob disease.

  Authors: A Shatunov, E A Fridman, F I Pagan, J Leib, A Singleton, M Hallett, L G Goldfarb

  Clinical genetics. 01/2005; 66(6):496-501.

  A 20-year-old North American patient developed rapidly progressive cognitive decline and pronounced ataxia, a phenotype compatible with prion disease. No structural changes were found in the PRNPA 20-year-old North American patient developed rapidly progressive cognitive decline and pronounced ataxia, a phenotype compatible with prion disease. No structural changes were found in the PRNP gene, which excludes genetic prion disease, but the patient's PRNP codon 129 Met/Met genotype is known to predispose to variant Creutzfeldt-Jakob disease (vCJD). Further studies identified an expanded allele with 55 CAG/CAA repeats in the TBP gene. The increase of trinucleotide repeat number in the coding region of the TBP gene has previously been associated with spinocerebellar ataxia type 17 (SCA17). The patient's unaffected parents and siblings show normal-size TBP alleles with 37-38 repeats. Haplotype and nucleotide sequence analyses clearly indicate that the mutation has occurred de novo on a paternal chromosome by insertion/duplication of a (CAA)(CAG)(CAA)(CAG)(15) sequence. This report presents a second fully investigated sporadic case of SCA17 occurring as a result of a DNA rearrangement within the polymorphic TBP trinucleotide repeat region. Our findings suggest that patients suspected of vCJD should undergo testing for SCA17, Huntington's disease and other neurodegenerative disorders having phenotypic similarities with vCJD.

• Open-label dose-escalation study of oral 1-octanol in patients with essential tremor.

  Authors: H A Shill, K O Bushara, Z Mari, M Reich, M Hallett

  Neurology. 07/2004; 62(12):2320-2.

  Twenty-one single oral doses of 1-octanol were given to patients with essential tremor (ET) in an open-label dose-escalation study. The drug was well tolerated up to 64 mg/kg. The main side effectTwenty-one single oral doses of 1-octanol were given to patients with essential tremor (ET) in an open-label dose-escalation study. The drug was well tolerated up to 64 mg/kg. The main side effect was an unusual taste. No overt intoxication was seen. There was evidence for efficacy, with a significant reduction in tremor amplitude as measured by accelerometry and handwriting that was maximal at 2 hours. Higher doses may produce more sustained benefit.

• Flumazenil does not affect intracortical motor excitability in humans: a transcranial magnetic stimulation study.

  Authors: H Y Jung, Y H Sohn, A Mason, E Considine, M Hallett

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 03/2004; 115(2):325-9.

  OBJECTIVE: The motor cortex may be subject to tonic inhibitory drive. One inhibitory mechanism is supported by activity at benzodiazepine (BZP) receptors. In this study we investigate whether or notOBJECTIVE: The motor cortex may be subject to tonic inhibitory drive. One inhibitory mechanism is supported by activity at benzodiazepine (BZP) receptors. In this study we investigate whether or not the BZP antagonist, flumazenil, increases cortical motor excitability in humans. METHODS: Eight healthy subjects received a 1 mg intravenous (i.v.) loading dose of flumazenil followed by a 0.5 mg i.v. infusion over the next 30 min. Before, during, and 1 h after flumazenil infusion, we measured cortical motor excitability using transcranial magnetic stimulation (TMS). This included resting motor threshold (rMT), paired-pulse measurements of intracortical inhibition and facilitation (ICI and ICF), recruitment curve (RC), and silent period (SP). We also measured F response and compound muscle action potential (CMAP) with peripheral nerve stimulation. The study was carried out using a randomized, double-blind crossover design controlled with a saline infusion. RESULTS: None of the measures of cortical or peripheral excitability were significantly affected by drug administration. CONCLUSIONS: Our findings suggest that flumazenil has no effect on cortical motor excitability in normal humans. SIGNIFICANCE: There does not appear to be any tonic activity at benzodiazepine receptors in the normal resting human motor cortex.

• Cortical control of voluntary blinking: a transcranial magnetic stimulation study.

  Authors: Y H Sohn, B Voller, M Dimyan, A St Clair Gibson, T Hanakawa, F E Leon-Sarmiento, H Y Jung, M Hallett

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 03/2004; 115(2):341-7.

  OBJECTIVE: To investigate cortical regions related to voluntary blinking. METHODS: Transcranial magnetic stimulation (TMS) was applied to the facial motor cortex (M1) and the midline frontal regionOBJECTIVE: To investigate cortical regions related to voluntary blinking. METHODS: Transcranial magnetic stimulation (TMS) was applied to the facial motor cortex (M1) and the midline frontal region (Fz) in 10 healthy subjects with eyes opened and closed. Motor-evoked potentials were recorded from the orbicularis oculi (OOC), orbicularis oris (OOR), abductor digiti minimi and tibialis anterior using surface and needle electromyography electrodes. Facial M waves and blink reflex were measured using supramaximal electrical stimulation of the facial and supraorbital nerves. RESULTS: TMS at Fz elicited 3 waves in OOC with no response in other tested muscles except for the early wave in OOR. Facial M1 stimulation produced only early and late waves. Because of their latencies, shapes, and relationship to coil position and stimulation intensity, early and late waves appeared to be analogous to the facial M wave and R1 component of the blink reflex. The intermediate wave at 6-8 ms latency was elicited in OOC by Fz stimulation with eyes closed. CONCLUSIONS: Since its latency matches the central conduction time of other cranial muscles and it has characteristic of muscle activation-related facilitation, the intermediate wave is presumably related to cortical stimulation. This result provides evidence that the cortical center for the upper facial movements, including blinking, is not principally located in the facial M1, but rather in the mesial frontal region.

• Pilot trial of 1-octanol in essential tremor.

  Authors: K O Bushara, S R Goldstein, G J Grimes, A H Burstein, M Hallett

  Neurology. 02/2004; 62(1):122-4.

  1-Octanol (an 8-C alcohol currently used as a food-flavoring agent) is known to inhibit tremor in essential tremor (ET) animal models at a much lower dose than ethyl alcohol. The authors conducted a1-Octanol (an 8-C alcohol currently used as a food-flavoring agent) is known to inhibit tremor in essential tremor (ET) animal models at a much lower dose than ethyl alcohol. The authors conducted a randomized, placebo-controlled pilot trial of a single oral dose of 1 mg/kg of 1-octanol in 12 patients with ET. No significant side effects or signs of intoxication were observed. 1-Octanol significantly decreased tremor amplitude for up to 90 minutes. The results suggest 1-octanol as a well-tolerated and safe potential treatment for ET. Further trials are warranted.

• Abnormalities of spatial discrimination in focal and generalized dystonia.

  Authors: F M Molloy, T D Carr, K E Zeuner, J M Dambrosia, M Hallett

  Brain : a journal of neurology. 11/2003; 126(Pt 10):2175-82.

  Sensory processing is impaired in focal hand dystonia (FHD), with most previous studies having evaluated only the symptomatic limb. The purpose of this study was to establish whether the sensorySensory processing is impaired in focal hand dystonia (FHD), with most previous studies having evaluated only the symptomatic limb. The purpose of this study was to establish whether the sensory system is affected in other types of dystonias and whether the contralateral hand is also involved in FHD. We used a spatial acuity measure (Johnson-Van Boven-Phillips domes) to evaluate sensory spatial discrimination in both hands of patients with different forms of dystonias including primary generalized DYT1 dystonia (associated with a unique deletion in the DYT1 gene) (n = 13), FHD (n = 15), benign essential blepharospasm (n = 9), cervical dystonia (n = 10) and in age-matched controls. Clinical evaluation included the Fahn dystonia scale for the focal dystonia groups and the Marsden-Burke-Fahn scale for the generalized dystonia group. Spatial discrimination was normal in patients with DYT1 dystonia, despite all of these patients having hand dystonia. However, spatial discrimination thresholds were significantly increased in both hands in the focal dystonia groups (thresholds were similar for each group) and did not correlate significantly with either severity or duration of dystonic symptoms. Thresholds were significantly increased in the dominant hand compared with the non-dominant hand only within the FHD group. Our observations demonstrate involvement of both the dominant and non-dominant somatosensory cortices, and suggest that abnormal sensory processing is a fundamental disturbance in patients with focal dystonia. These findings of altered sensory processing in idiopathic focal but not generalized DYT1 dystonia suggest both a primary pathophysiological role for the phenomenon in focal dystonia and divergent pathophysiological processes in the two conditions.

• Accelerometry to distinguish psychogenic from essential or parkinsonian tremor.

  Authors: K E Zeuner, R O Shoge, S R Goldstein, J M Dambrosia, M Hallett

  Neurology. 09/2003; 61(4):548-50.

  The authors measured postural wrist tremor with accelerometry in patients with psychogenic (n = 6), essential (n = 11), and parkinsonian (n = 12) tremor. Tremor was measured in one hand, while theThe authors measured postural wrist tremor with accelerometry in patients with psychogenic (n = 6), essential (n = 11), and parkinsonian (n = 12) tremor. Tremor was measured in one hand, while the other hand either rested or tapped to an auditory stimulus at 3 and 4 or 5 Hz. Psychogenic tremors showed larger tremor frequency changes and higher intraindividual variability while tapping. Accelerometry may differentiate psychogenic from essential and parkinsonian tremor.

• The effect of transcranial magnetic stimulation on movement selection.

  Authors: Y H Sohn, A Kaelin-Lang, M Hallett

  Journal of neurology, neurosurgery, and psychiatry. 08/2003; 74(7):985-7.

  OBJECTIVE: To attempt to replicate previous findings that showed an influence of transcranial magnetic stimulation of the cortical motor areas on the selection of motor programmes on theOBJECTIVE: To attempt to replicate previous findings that showed an influence of transcranial magnetic stimulation of the cortical motor areas on the selection of motor programmes on the contralateral side. METHODS: Healthy volunteers were asked to choose to make a right or left index finger extension movement freely after hearing the click produced by transcranial magnetic stimulation. The stimulation was applied to the motor areas (test), including the motor cortex, vertex, and prefrontal cortex, and in the air (control). RESULTS: There was no preference for choosing the hand contralateral to the stimulation site, in either test or control trials. CONCLUSIONS: Previous results could not be reproduced. Simple magnetic stimulation of the motor areas is insufficient to affect voluntary selection of movement.

• Transcranial magnetic stimulation techniques in clinical investigation.

  Authors: A Currà, N Modugno, M Inghilleri, M Manfredi, M Hallett, A Berardelli

  Neurology. 01/2003; 59(12):1851-9.

  Transcranial magnetic stimulation (TMS) is a technique that can activate cortical motor areas and the corticospinal tract without causing the subject discomfort. Since TMS was introduced, numerousTranscranial magnetic stimulation (TMS) is a technique that can activate cortical motor areas and the corticospinal tract without causing the subject discomfort. Since TMS was introduced, numerous applications of the technique have been developed for the evaluation of neurologic diseases. Standard TMS applications (central motor conduction time, threshold and amplitude of motor evoked potentials) allow the evaluation of motor conduction in the CNS. Conduction studies provide specific information in neurologic conditions characterized by clinical and subclinical upper motor neuron involvement. In addition, they have proved useful in monitoring motor abnormalities and the recovery of motor function. TMS also gives information on the pathophysiology of the processes underlying the various clinical conditions. More complex TMS applications (paired-pulse stimulation, silent period, ipsilateral silent period, input-output curve, and evaluation of central fatigue) allow investigation into the mechanisms of diseases causing changes in the excitability of cortical motor areas. These techniques are also useful in monitoring the effects of neurotrophic drugs on cortical activity. TMS applications have an important place among the investigative tools to study patients with motor disorders.