Abnormal cortical processing of voluntary muscle relaxation in patients with focal hand dystonia studied by movement-related potentials.
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In order to clarify the abnormality in cortical motor preparation for voluntary muscle relaxation of the hand in patients with focal hand dystonia, Bereitschaftspotentials (BPs) preceding voluntary muscle contraction and relaxation were recorded in eight patients (three with simple writer's cramp and five with dystonic writer's cramp), and were compared with those from 10 normal subjects. Voluntary muscle relaxation: after keeping the right wrist in an extended position for > 5 s, the subject let the hand drop by voluntarily terminating muscle contraction of the wrist extensor without any associated muscle contraction. Voluntary muscle contraction: the right wrist was flexed by voluntarily contracting the wrist flexor muscle. Scalp EEGs were recorded from 11 electrodes placed over the frontal, central and parietal areas. In the control group, the BP measured at the movement onset was maximal at the left central area (C1), and distributed predominantly over the left hemisphere equally in both the contraction and relaxation tasks. In the focal hand dystonia group, BP was maximal at C1 in the contraction task, whereas, in the relaxation task, it was maximal at the midline central area (Cz) and symmetrically distributed. At the left central area, the BP amplitude in the focal hand dystonia group was diminished significantly in the relaxation task compared with the contraction task (P < 0.05). The present results demonstrate for the first time that the cortical preparatory process for voluntary muscle relaxation, or motor inhibition, is abnormal in focal hand dystonia. (+info)
Improving communication between hospital and community physicians. Feasibility study of a handwritten, faxed hospital discharge summary. Discharge Summary Study Group.
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OBJECTIVE: To assess the timing, legibility, and completeness of handwritten, faxed hospital discharge summaries as judged by family physicians and to obtain their opinion on the information categories on a standardized discharge summary form. DESIGN: Fax survey of physicians for consecutive patients discharged from hospital over 8 weeks. SETTING: Three wards in a tertiary care teaching hospital. PARTICIPANTS: One hundred two family physicians and general practitioners practising in Hamilton, Ont. MAIN OUTCOME MEASURES: Proportions of summaries that were received, received within 48 hours of discharge, legible, and complete; types of information missing from incomplete summaries; proportion of physicians satisfied with the information categories. RESULTS: Of 271 consecutive patient discharges, 195 (72%) were eligible for study. Among those ineligible, 22 patients (8%) did not have a family doctor identified on their hospital records. Among records that did have a family physician identified, fax numbers were unavailable or unknown for 54 physicians (20%). One hundred two physicians completed 166 discharge summary assessments for a response rate of 85% (166/195). By 3 weeks after discharge, 138 discharge summaries (83%) had been received by patients' family doctors. Among those received, 86% were received within 48 hours of discharge; 92% were legible; and 88% were complete. Hospital doctors' signatures, patients' diagnoses, and follow-up plans were most frequently missing. Ninety-five percent of physicians were satisfied with the information categories included on the standardized form. CONCLUSIONS: Handwritten, faxed hospital discharge summaries were acceptable to family physicians for most patients. Criteria are needed for determining which patients require both handwritten and dictated discharge summaries. (+info)
Human arm movements described by a low-dimensional superposition of principal components.
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A new method for analyzing kinematic patterns during smooth movements is proposed. Subjects are asked to move the end of a two-joint manipulandum to copy a smooth initial target path. On subsequent trials the target path is the subject's actual movement from the preceding trial. Using Principal Components Analysis, it is shown that the trajectories have very low dimension and that they converge toward a linear superposition of the first few principal components. We show similar results for handwriting on an electronic pen tablet. We hypothesize that the low dimensionality and convergence are attributable to combined properties of the internal controller and the musculoskeletal system. The low dimensionality may allow for efficient descriptions of a large class of arm movements. (+info)
An electromyographic study of two different types of ballpoint pens--investigation of a one hour writing operation.
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Recently there has been an increasing incidence of occupational cervicobrachial disorders (OCD) and writer's cramp in office workers using ballpoint pens in writing operations. For the sake of workers who use ballpoint pens, it is essential to prevent such health hazards. It has been observed that a strong gripping pressure on the ballpoint pen significantly contributes to the development of these conditions. The present authors have been developing a new ballpoint pen by altering the grip area in such a way as to reduce the gripping pressure, and thus prevent OCD. The purpose of this study is to compare our ballpoint pen (new pen) with a conventional ballpoint pen (conventional pen) for the load that they exert on the upper limb during one hour of continuous writing. Electromyograms (EMG) and upper limb pain scores are used as indicators. The conventional pen used was selected from commercially available ballpoint pens widely used in offices. The grip area is cylindrical with an 8.3 mm diameter. It is manufactured of hard plastic, which can make it feel rigid and slippery to the user. The new pen has a cylindrical grip area that flares out at the bottom, near the pen-tip, and has a diameter ranging from 11.9-13.6 mm. In addition, the grip is constructed of a 2 to 3 mm-thick silicon rubber sleeve that is softer and less slippery in comparison with the conventional pen. Twelve students (5 males and 7 females) without any preexisting cervicobrachial disorders were asked to transcribe an English text for one hour, alternately using the two kinds of pens. The EMG of the flexor pollicis brevis was measured and recorded every second, while subjective pain scores were recorded every five minutes for the thumb, forefinger, middle finger, thenar, forearm extensor (forearm) and shoulder. The EMG of the flexor pollicis brevis and the pain scores for the thumb, forefinger, middle finger, forearm and shoulder were significantly lower for the new pen than for the conventional pen. These results suggest that after an hour of continuous writing, the new pen reduces the muscle load on the upper limb, and therefore mitigates fatigue in this area. (+info)
Essential role of the right superior parietal cortex in Japanese kana mirror reading: An fMRI study.
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Functional magnetic resonance imaging (fMRI) was used to investigate the neural substrates responsible for Japanese kana mirror reading. Japanese kana words, arranged vertically from top to bottom, were used in the mirror reading task in 10 normal right-handed Japanese adults. Since both mirror-reversed and normally oriented kana items are read in the same (top to bottom) direction, it was possible to minimize the oculomotor effects which often occur in the process of mirror reading of alphabetical language. By using the SPM96 random effect analysis method, a significant increase in the blood oxygen level-dependent signal during mirror reading relative to normal reading was detected in multiple brain regions, including the bilateral superior occipital gyri, bilateral middle occipital gyri corresponding to Brodmann area (BA) 18/19, bilateral lingual gyri (BA 19), left inferior occipital gyrus (BA 18), left inferior temporal cortex (BA 37), bilateral fusiform gyri (BA 19), right superior parietal cortex (SPC) (BA 7), left inferior frontal gyrus (BA 44/45) and an inferior part of the left BA 6. In addition to these cortical regions, the right caudate nucleus and right cerebellum were also activated. The activation found in the right SPC and the left inferior temporal region is consistent with the hypothesis that mirror reading involves both the dorsal visuospatial and ventral object recognition pathways. In particular, a significant correlation was found between the fMRI signal change in the right SPC and the behavioural performance (error index) in the task. This may reflect increased demand on the right SPC for the spatial transformation which is required for the accurate recognition of mirror-reversed kana items. This relationship between the haemodynamic response in a specific brain area and the behavioural data provides new evidence for the essential role of the right SPC in Japanese kana mirror reading. (+info)
Motor control: Mechanisms of motor equivalence in handwriting.
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Handwriting is a classic example of how the details of movement can be scale and plane invariant: letter forms reflecting personal style are unchanged, whether one is writing on a piece of paper, on a blackboard or in the sand using the foot. Recent research points to a role for the parietal cortex in such motor equivalence. (+info)
Participation of the left posterior inferior temporal cortex in writing and mental recall of kanji orthography: A functional MRI study.
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To examine the neuropsychological mechanisms involved in writing kanji (morphograms), we used functional MRI (fMRI) in 10 normal volunteers, all right-handed, native Japanese speakers. The experimental paradigms consisted of kana-to-kanji transcription, mental recall of kanji orthography and oral reading and semantic judgement of kana words. The first two tasks require manual and mental transcription of visually presented kana words into kanji, respectively, whereas the last two tasks involve language processing of the same set of stimulus words without recall of kanji. The transcription and mental recall tasks yielded lateralized activation of the left posterior inferior temporal cortex (PITC). By contrast, neither oral reading nor semantic judgement produced similar activation of the area. These results, in good accordance with lesion data, provide converging evidence that the left PITC plays an important role in writing kanji through retrieval of their visual graphic images, and suggest language-specific cerebral organization of writing. The set of fMRI experiments also provides new neuroimaging data on the cortical localization of basic language functions in people using a non-alphabetical language. (+info)
Kinematic analysis of handwriting movements in patients with obsessive-compulsive disorder.
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OBJECTIVES: Basal ganglia dysfunction is supposed to play a part in the pathophysiology of obsessive-compulsive disorder (OCD). A new computer aided technique for the analysis of hand movements, allowing the detection of subtle motor performance abnormalities, was applied in this study of patients with OCD and healthy controls. METHODS: Using a digitising graphic tablet, hand motor performance was studied in 22 unmedicated patients with OCD and compared with 22 healthy controls. All subjects drew superimposed concentric circles with both the right and the left hand, in addition to writing a given sentence, their personal signature, and letter sequences in four different sizes. Kinematic parameters were calculated to quantify hand motion. RESULTS: Patients with OCD had significant impairments of handwriting performance, reflected by lower peak velocity (sentence t=3.6; p=0.001; signature t=2.8; p=0.01) and micrographia (sentence t=3.4; p=0.002; signature t=2.5; p=0.02), compared with controls and shortened acceleration phases per stroke (sentence t=2.4; p=0.02; signature t=4.1; p=0.000). By contrast, in repetitive drawing, patients with OCD had higher peak velocity than healthy controls (group x task interaction p<0.01). There were no significant differences in left and right hand performance between groups. Patients with early versus late age of onset differed in handwriting parameters, such as handwriting consistency. Greater severity of obsessions and compulsions correlated with increasingly poor handwriting performance in patients with OCD. CONCLUSIONS: A subtle motor dysfunction in OCD can be detected with a digitising tablet. The findings show handwriting impairments in patients with OCD, in line with the assumption that basal ganglia dysfunction is part of OCD pathophysiology. Repetitive motor pattern performance was not impaired, but rather tended to be even better in patients with OCD than in controls. The findings also support the concept that patients with OCD with early versus late age of onset differ in pathophysiological mechanisms and basal ganglia dysfunction. (+info)