LAUSR

Dysgraphia refers to impaired handwriting due to abnormal orthographic coding or finger sequencing and can be broadly categorized into central and peripheral dysgraphia. The former involves spelling retrieval, assembly, and the generation of an abstract graphemic representation. The latter involves the process of externalizing a graphemic representation (i.e., handwriting, oral spelling, typing, or letter arranging). The processes involved in the production of handwriting are complex. First, graphemes (i.e., letters or letter groups) are set up via the lexical look-up or phoneme-to-grapheme correspondence rules. Second, features such as letter shape, case, and stroke sequence are specified by effector-independent allographs. Last, the written trace is generated by the activation of effectorspecific motor programs, which indicate muscle activation patterns for the graphemes. Impairment at any stage in this process will lead to dysgraphia. This report describes an unusual case of dysgraphia, wherein the patient had difficulty writing a specific letter. Although the concept of dysgraphia has been commonly described, the involvement of a single letter has not been previously reported. A 40-year-old man presented at our movement disorders clinic with a 12-year history of difficulty writing. The symptom was insidious in onset and restricted to writing the letter “t” in Bengali ( ). The patient described the difficulty as a momentary hesitation associated with tremulousness of hand while attempting to write the initial segment of the letter, after which he was able to write fluently. This problem persisted irrespective of the position of the letter in a word. He denied the presence of a similar difficulty with other letters in Bengali or while writing in English. The patient had no other complaints and had an unremarkable medical and family history. On examination, the patient was able to write the English alphabet in upper and lower case and numbers fluently with no evidence of hesitancy or tremulousness (Video 1, Segment 1). Upon writing the Bengali alphabet, an abnormality was observed while the patient wrote the letter (Video 1, Segment 1). There was no abnormality observed while writing the other letters. The abnormality was restricted to the initial segment of the letter when a rapid, jerky movement of the hand with increased activity of the wrist extensors and flexors was observed, after which the rest of the letter was executed flawlessly (Video 1, Segment 2). A similar abnormality was also observed with the number “ ” (i.e., the number 3, which is structurally similar to the letter ). The patient was also made to write the word “tota” in Bengali and the hesitancy with writing the letter was once again observed (Video 1, Segment 2). Dysgraphia was also observed for the letter when a random string of letters and numbers were dictated to the patient. The patient was able to copy the letter and verbalize the letter normally. No dystonic posturing of either hand was observed, and the rest of his neurological examination was unremarkable. A computed tomography scan of the brain was normal. The video of the patient was taken after obtaining written informed consent. We evaluated the kinematics of this dysgraphia and hesitancy by utilizing a digitizing tablet (Wacom Intuos PTH-860) with a non-inking stylus. Data were collected and analyzed using NeuroScript’s MovAlyzeR (v.6.1.0.0). We used a healthy, age and education-matched control to confirm the presence of abnormal kinematics. A real-time recording of the patient writing the letter (Video 1, Segment 3) clearly demonstrates the presence of an initial hesitancy while executing the letter. Comparison of the kinematic properties of the letter , between the patient and control, revealed a significantly lower absolute velocity in the patient (0.97 ± 0.31 cm/s vs. 4.44 ± 1.59 cm/s, p < 0.01; Fig. 1). There was no significant difference in the axial pressure (556.73 ± 91.07 z-unit vs. 472.63 ± 94.72 z-unit, p > 0.05). The act of writing has been functionally and anatomically localized to the parietal cortex, in particular, the posterior parietal cortex and occipitotemporal junction and to a region of the middle temporal gyrus termed the Exner’s area or the graphemic/ motor frontal area. Depending on the site involved and the step of handwriting production affected, focal brain damage can affect handwriting in different ways, with symptoms ranging from dysgraphia to agraphia. For instance, Kapur et al. had reported a case with a left occipital space occupying lesion, who had dysgraphia for the letters H and B. In the current patient, the neurological examination was unremarkable except for the dysgraphia. Hence, the dysgraphia observed in this patient is unlikely to be