Final answer:
Slow writhing movements (athetosis) can be caused by Parkinson's disease and ataxia, which can be brought about by a variety of factors including exposure to toxins and genetic disorders.
Step-by-step explanation:
Athetosis, which refers to slow writhing movements, can be caused by various factors such as certain medical conditions, exposure to toxins, and genetic disorders.
In the case of Parkinson's disease, the death of neurons in the midbrain, specifically the buildup of protein structures called Lewy bodies, leads to motor symptoms including slow writhing movements.
Similarly, ataxia can cause slow writhing movements. Ataxia can be caused by exposure to substances like alcohol, drugs, or mercury, as well as focal lesions such as strokes or tumors affecting the cerebellum.