Dysfunction of the cerebrocerebellum (lateral hemispheres) presents as disturbances in carrying out voluntary, planned movements by the extremities (called appendicular ataxia). These include:
Intention tremor (coarse trembling, accentuated over the execution of voluntary movements, possibly involving the head and eyes, as well as the limbs and torso)
Peculiar writing abnormalities (large, unequal letters, irregular underlining)
A peculiar pattern of dysarthria (slurred speech, sometimes characterised by explosive variations in voice intensity despite a regular rhythm)
Inability to perform rapidly alternating movements, known as dysdiadochokinesia, occurs, and could involve rapidly switching from pronation to supination of the forearm. Movements become more irregular with increases of speed. Inability to judge distances or ranges of movement happens. This dysmetria is often seen as undershooting, hypometria, or overshooting, hypermetria, the required distance or range to reach a target. This is sometimes seen when a patient is asked to reach out and touch someones finger or touch his or her own nose. The rebound phenomenon, also known as the loss of the check reflex, is also sometimes seen in patients with cerebellar ataxia, for example, when  patients are flexing their elbows isometrically against a resistance. When the resistance is suddenly removed without warning, the patients arms may swing up and even strike themselves. With an intact check reflex, the patients check and activate the opposing triceps to slow and stop the movement. Patients may exhibit a constellation of subtle to overt cognitive symptoms, which are gathered under the terminology of Schmahmanns syndrome.
Oral retinoids (e.g., acitretin, etretinate) may be helpful in treating arsenic-induced cutaneous lesions and in reducing the risk of cutaneous and internal malignancy formation, especially in Bowmans disease. Topical 5-fluorouracil cream or 5% imiquimod cream may be useful in treating arsenical keratoses and Bowens disease. == References ==