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Behavioural Neurology
Volume 19 (2008), Issue 4, Pages 169-175

Dysgraphia in Patients with Primary Lateral Sclerosis: A Speech-Based Rehearsal Deficit?

S. Zago,1,2 B. Poletti,2 M. Corbo,2 L. Adobbati,2 and V. Silani2

1Department of Neurological Sciences, University of Milan Medical School, IRCCS Ospedale Maggiore-Policlinico, Mangiagalli e Regina Elena–IRCCS Istituto Auxologico Italiano, Milano, Italy
2Department of Neurology and Laboratory of Neuroscience, ‘Dino Ferrari Center’, University of Milan Medical School, IRCCS Istituto Auxologico Italiano, Milano, Italy

Received 16 December 2008; Accepted 16 December 2008

Copyright © 2008 Hindawi Publishing Corporation and the authors. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The present study aims to demonstrate that errors when writing are more common than expected in patients affected by primary lateral sclerosis (PLS) with severe dysarthria or complete mutism, independent of spasticity. Sixteen patients meeting Pringle’s et al. [34] criteria for PLS underwent standard neuropsychological tasks and evaluation of writing. We assessed writing abilities in spelling through dictation in which a set of words, non-words and short phrases were presented orally and by composing words using a set of preformed letters. Finally, a written copying task was performed with the same words. Relative to controls, PLS patients made a greater number of spelling errors in all writing conditions, but not in copy task. The error types included: omissions, transpositions, insertions and letter substitutions. These were equally distributed on the writing task and the composition of words with a set of preformed letters. This pattern of performance is consistent with a spelling impairment. The results are consistent with the concept that written production is critically dependent on the subvocal articulatory mechanism of rehearsal, perhaps at the level of retaining the sequence of graphemes in a graphemic buffer. In PLS patients a disturbance in rehearsal opportunity may affect the correct sequencing/assembly of an orthographic representation in the written process.