Tachymicrographia following bilateral globus pallidal haemorrhage: a case report and quantitative analysis of writing velocity and a compensatory writing tool

Progressive supranuclear palsy and damage to the globus pallidus can cause tachymicrographia (TM), a symptom characterised by abnormally small and rapid handwriting. However, the character size and handwriting velocity in patients with TM have not been quantitatively analysed. Furthermore, only one report has addressed rehabilitative approaches for this condition. Herein, we characterised TM in a single patient with bilateral globus pallidus haemorrhage, using quantitative handwriting analysis across three predefined domains to assess the type of micrographia, to distinguish intra-character stroke velocity from inter-character transitions, and evaluate the impact of a compensatory, flexible writing implement on TM and writing readability. We report a case of a 41-year-old right-handed man who presented with TM after intracerebral haemorrhage due to hypertensive encephalopathy, with lesions in the left temporoparietal region and bilateral globus pallidus. He wrote abnormally small characters at an unusually fast speed. Consequently, the written characters became significantly distorted. Quantitative analysis showed consistently smaller characters than those of neurologically healthy controls (continuous micrographia) and a markedly faster velocity during transitions between characters; contrarily, the velocity of drawing the lines forming each character did not differ. However, the patient exhibited no decrease in character size, acceleration of writing, or distortion of characters when using a flexible writing implement designed to reduce repulsive force from the writing surface. This compensatory approach markedly improved legibility and writing performance. Although the mechanism of TM in this patient cannot be explained neurophysiologically, we considered the possibility that an excessive response to sensory input associated with repulsive force had occurred within the cortico-basal ganglia-thalamo-cortical loop, including the globus pallidus. Reducing repulsive force with a flexible writing tool effectively suppressed the symptom, suggesting a potential, practical rehabilitative strategy. Further studies should determine whether similar quantitative profiles and compensatory effects can be generalised to other patients with TM associated with globus pallidus involvement, such as those with progressive supranuclear palsy.