Micrographia is a frequent symptom of Parkinson’s disease, often one of the first. Its association with the disease is straightforward: 75-90% of patients with Parkinson show micrographia, the presence of micrographia allows the diagnosis of PD in almost all cases. In other less frequent disorders, micrographia is associated with other parkinsonisms (Huntington’s disease, Wilson’s disease, Progressive Supranuclear Palsy, Binswanger’s disease and so on), which have degenerative, genetic or vascular causes and which all impair basal ganglia circuits as it happens with PD.
Micrographia denotes a small handwriting, which generally is also slow and less accurate. Micrographia can be also detected by asking to the patient to write by air movements of the fingers. Patients with handwriting do also small drawings (see the watch in the figure).
Specific software on computer and tablets allows measuring accurately the handwriting characteristics (size, duration, speed and fluency). Such digital measures of handwriting would help formulating the diagnosis of PD in the earlier phases. It would be important for PD diagnosis, even, without any specific measure, to compare visually the actual handwriting of the patients with the previous examples of the years before.
Two variants are described, although, they often coexist in the same patient. “Constant micrographia” is the constantly reduced form of the small handwriting. This is the general and distinctive feature of the micrographia itself. On the other hand, “Progressive micrographia” is the tendency for handwriting to reduce progressively its size more and more in the course of writing. This corresponds to the general “sequence effect”, a well-known phenomenon in patients with PD or other parkinsonisms, consisting in progressively reducing the amplitude and fluency of motor sequences (parkinsonian gait festination and/or gait freezing are examples). Similar to the progressive micrographia, in the case of gait festination, the patient involuntarily moves with short, accelerating steps, often on tiptoe, with the trunk flexed forward and the legs flexed stiffly at the hips and knees.
The “constant micrographia” is the direct expression of the dysfunction of dopaminergic motor circuits of the basal ganglia and can improve with levodopa or by training in handwriting rehabilitation. Progressive micrographia is determined by the dysfunction of larger connectivity of brain areas (including cerebellum or parietal and motor/premotor cortical areas) and less responsive to dopamine or rehabilitative programs.
Micrographia should be assessed and measured with digital instruments in PD patients, not only for diagnostic purposes but also to monitor and quantify the improvement of patients with pharmacological and rehabilitative treatments.
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