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Pattern Specific Dysgraphia—Beyond Letter Specificity

Jacky Ganguly,S. Choudhury,Hrishikesh Kumar

Published 2023 in Movement Disorders Clinical Practice

ABSTRACT

We have read with great interest the article by Prasad et al describing a patient with letter specific dysgraphia. In relation to this, we would like to share our experience with a patient having difficulty in writing the initial segment of multiple letters of English and Bengali language, those require a particular pattern to initiate. A 52-year-old male patient presented with history of difficulty in writing a few particular letters for last the 6 years. He felt stuck and took more time to initiate writing those letters, after which he could write the rest of letter fluently. The problem persisted irrespective of the position of those letters in a word. He felt no difficulty in writing other letters or in any other manual tasks. There was no significant family history. On examination, the difficulty noted in writing the following letters: c (in English) and অ, আ, ই, ঈ, এ, ঐ, ও, ঔ, খ, ত, থ, ধ, ন, ভ, ল, হ, ৎ (in Bengali) (Video 1). All these letters have a commonality, requiring a particular type of hand movement (circling) to initiate and then have to move the pen either in clockwise (অ, আ, ই, ঈ, এ, ঐ, ও, ঔ, ত, থ, ন, ল, হ) or anti-clockwise (c, খ, ধ, ভ, ৎ) manner. The patient got stuck in these initial segments and took longer than the usual time to get out of that. Once the initial segment was over, he could finish writing these letters perfectly. No dystonic posturing noted in upper limbs or anywhere else. The rest of the neurological examination was unremarkable. MRI brain was normal. We have assessed the kinematics of writing using a digitizing tablet with a non-inking stylus with a sampling rate of 100 Hz, in addition to real-time recording of the patient’s writing while asked to write the Bengali alphabet “ত”. The kinematic data was analyzed using NeuroScript’s MovAlyzeR (v.6.1.0.0) that showed start hesitation (Fig. 1A) and reduced velocity while writing in the patient (3 2.5 cm/s) (Fig. 1B) compared to matched healthy controls (10 8.3 cm/s, 0.0001) (Fig. 1D,E). The pen pressure is not significantly different between the patient (378 86 z unit) and matched control (370 95 z unit, p 0.392) as shown in Figure 1C,F (average of two consecutive trials). Initial task specificity to certain letters/numbers has been described in patients of Writer’s cramp by Shamim et al. However, the difficulty gradually progressed to more tasks and they showed other features of dystonia like mirror movements and increased pen pressure. On the contrary, in our patient the difficulty remained restricted to letters starting with a particular pattern. There were no mirror movements and pen pressure was normal.

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