Micrographia — that is, small-sized handwriting — long considered a symptom of Parkinson’s disease (PD), is also observed in patients with other neurodegenerative disorders. It sometimes pre-dates the onset of motor symptoms or follows damage to brain’s basal ganglia (a region essential to motor control), without any accompanying PD symptoms. This inconsistency suggests pathologically small handwriting is not necessarily due to the bradykinesia and rigidity associated with PD.
In this review article, Prof. Rivka Inzelberg, Prof. Tamar Flash and their colleagues review the evidence for the causes and contributors to micrographia, including lack of dopamine, loss of movement smoothness, impairments in motor control and motion planning, loss of automaticity, and reduced movement vigor. They conclude that the primary cause of micrographia is lesions in the basal ganglia — common in PD, but not exclusive to it.