Barbara Baur

Circadian Variations in the Kinematics of Handwriting and Grip Strength

The present study determined whether the motor process of handwriting is influenced by a circadian rhythm during writing tasks of high everyday relevance and analyzed the relationship to the circadian rhythm of grip strength. Ten healthy young male subjects underwent a 40 h sleep‐deprivation protocol under constant routine conditions. Starting at 09:00 h, subjects performed three handwriting tasks of increasing perceptual‐motor complexity (writing a sentence, writing ones signature, and copying a text for 3 min) and assessed grip strength of both hands every 3 h. Handwriting performance was analyzed by writing speed, writing fluency, script size, break times, and pen pressure. The handwriting tasks revealed a coincident circadian rhythm for the frequency of handwriting as a measure of movement speed, with slowest writing speed at 03:16 h. A weak effect of task complexity was evident for the non‐writing episodes: while copying a text, break times were influenced by a circadian rhythm, whereas during sentence writing, the non‐writing episodes remained constant. The circadian rhythm of grip strength paralleled the time course of motivation ratings, with least motivation and weakest grip strength around 06:00 h concurrently for both hands. The rate of force production also displayed circadian rhythmicity and sharply decreased with the onset of melatonin secretion. Neither grip strength nor the kinematics of handwriting was influenced by sleep deprivation; only the level of the force rate was decreased the second day. The results show a clear circadian rhythm in the speed of handwriting and grip strength.

Effects of deep brain stimulation on prehensile movements in PD patients are less pronounced when external timing cues are provided

It has been repeatedly demonstrated that the movements of patients with Parkinsons disease (PD) are less impaired when external timing cues are provided. This suggests that the basal ganglia, which are impaired in PD, are less involved in the control of externally timed movements. In the present study, we tested this hypothesis by contrasting the effect of deep brain stimulation (DBS) in the basal ganglia (more precisely, the internal globus pallidum) on internally versus externally timed movements. Our first movement task was a standard prehensile task involving a reach-to-grasp movement. In the externally-timed condition, the target object was moving rapidly away from the subject; in the internally-timed condition, the target object was stationary. We found, that for most aspects of the prehensile movement the effect of DBS was less pronounced in the externally than in the internally timed condition. A similar reduction of the DBS effects in the externally-timed condition was also found for a second movement task, which required an isolated grasping movement. We conclude that the basal ganglia are significantly less involved in the control of externally timed movements.

Significance of finger forces and kinematics during handwriting in writer’s cramp

Muscular hyperactivity during handwriting, irregular and jerky scripts, as well as awkward and slowed pen movements are the cardinal symptoms of writers cramp. Accordingly, impaired kinematics and increased force have been reported in writers cramp. However, the relationship between these symptoms has rarely been investigated. In addition, measurements of finger forces have been restricted to the vertical pen pressure. In the present study, the pen of a graphic tablet was equipped with a force sensor matrix to measure also the grip force produced against the pen barrel despite highly variable pen grips of the patients. Kinematics of writing movements, vertical pen pressure, and grip force were compared in 27 patients with writers cramp and normal control writers during writing of a test sentence. As expected, all measures revealed a significantly worse writing performance in the patients compared to the control subjects. Exaggerated forces were more frequent than abnormal kinematics, and evidenced by prolonged movement times and reduced writing frequencies. Correlations were found neither between kinematics and force measures nor between the two forces. Interestingly, patients relaxed the grip force during short periods of non-writing by the same relative amount as control subjects. The finding of a large heterogeneity of performances patterns in writers cramp may reflect the variability of dystonic symptoms as well as the highly variable compensatory strategies of individual patients. Measurements of finger force and in particular of the grip force are valuable and important descriptors of individual impairment characteristics that are independent of writing kinematics.

Auditory Grip Force Feedback in the Treatment of Writer's Cramp

STUDY DESIGN Pre-post, single-group. INTRODUCTION Writers cramp (WC) is a focal dystonia causing impairments in daily life. Behavioral treatment approaches have been shown to improve handwriting performance, though outcomes remain sub-optimal. PURPOSE OF THE STUDY To examine the effects of the handwriting training and auditory grip force feedback in seven patients with WC. METHODS Handwriting performance was examined before and after treatment. Writing frequency, fluency, and pressure were recorded with a digitizing tablet and grip forces during handwriting were recorded. Subjective writing performance and pain were rated on visual analog scales. RESULTS The treatment resulted in significant reductions in writing pressure and pain, while writing performance was significantly improved. CONCLUSIONS Patients in this study with WC, who exhibit grip force and pressure problems, benefit from feedback-supported handwriting training.

Effects of Modified Pen Grip and Handwriting Training on Writer's Cramp

OBJECTIVE To evaluate the use of a modified pen grip and subsequent handwriting training in patients with writers cramp (WC). DESIGN Handwriting performance with normal and modified pen grip was examined once in healthy controls and repeatedly in patients with WC (2 baseline tests before training, directly after training, after a 3-month follow-up). SETTING Ambulatory care for motor writing disorders. PARTICIPANTS Patients with WC (n=26) and healthy controls (n=14). INTERVENTION Seven sessions of handwriting training with various motor exercises were conducted by an occupational therapist. During training, the patients always used a modified pen grip (stabilized between index and middle finger). MAIN OUTCOME MEASURES Writing frequency and fluency, grip force on the pen, writing pressure, Fahn dystonia scale, visual analog scales for impairment and pain. RESULTS Patients with WC showed increased writing pressure and grip force before training. Using the modified pen grip caused in both patients with WC and controls a decrease in pressure and grip force. Handwriting training resulted in a further improvement of both parameters in patients with WC. Grip force reduction remained stable over follow-up. CONCLUSIONS Results suggest that patients with WC benefit from the use of the modified pen grip in combination with handwriting training.

Music memory provides access to verbal knowledge in a patient with global amnesia

Abstract We report on the patient CH, who showed marked impairment of declarative memory in everyday life and standardized memory tests subsequent to herpes simplex encephalltis. However, there was anecdotal evidence for preserved learning capacity for verbal material (song titles) in connection with playing accordion music. Our experiments, tallored to CHs individual accordion repertoire, confirmed strong associations between language (song titles) and music (accordion melodies): CH performed 100% of the melodies correctly after being presented with the respective song titles. Presented with melodies, she recognized 90% of the titles out of several distractors. This good verbal memory success is conspicuous in the light of her otherwise severe memory impairments. To elucidate the phenomenon, we examined additionally the semantic knowledge concerning music-associated verbal material in CH by definition, categorization, reading and naming tasks. If music-associated words belonged to an actually better preserved or relearned vocabulary, we would have expected CH to perform better with music-associated concepts than with comparable, non-music-associated concepts. However, that was not the case. CHs good verbal memory in a musical context may be explained in terms of a material-specific, semantically empty priming effect.

Der Schreibkrampf Ätiologie, Untersuchung und Therapie

Die Begriffe Schreibkrampf oder Graphospasmus beschreiben eine isolierte Storung der Schreibbewegungen. Die klinische Symptomatik ist gekennzeichnet durch eine unwillkurliche und zum Teil sehr schmerzhafte Verkrampfung zahlreicher Muskeln der Hand, des Unterarmes und sogar des Oberarmes einschlieslich des Schulterbereiches beim Schreiben. Besonders auffallend sind die extremen Gelenkstellungen und die teilweise bizarren Stifthaltungen. Typischerweise werden die Gelenke versteift und der Stift wird mit enormen Kraften gehalten. Zusatzlich wird mit Handgelenk oder Unterarm starker Druck auf die Schreibunterlage ausgeubt. Manchmal besteht gleichzeitig ein Tremor der betroffenen Hand. Bereits einfache Aufgaben wie das Unterschreiben von Uberweisungsformularen mit Durchschlag oder das Aufschreiben von Notizen wahrend eines Telefongesprachs konnen Patienten mit Schreibkrampf grose Schwierigkeiten bereiten. Manche Patienten konnen schon nach ein paar Wortern nicht mehr weiterschreiben, bei anderen Patienten treten die Probleme erst nach langerem Schreiben auf. Das Gefuhl, beim Schreiben beobachtet zu werden, kann die Symptome erheblich verstarken. Dabei ist nicht nur die Schreibleistung pro Zeiteinheit deutlich vermindert, haufig ist das Schriftbild beeintrachtigt und das Geschriebene nur noch schwer leserlich. Die Pravalenz des Schreibkrampfs wurde in einer epidemiologischen Studie auf 11-17 Falle pro Million in Europa geschatzt (The Epidemiological Study of Dystonia in Europe Collaborative Group 2000), in anderen Studien wird jedoch die Zahl von 8 auf 100 000 Einwohnern genannt.