Which type of reactions are characterized by distorted or impaired voluntary muscle movements?

Dystonic reactions are specifically characterized by distorted or impaired voluntary muscle movements. This condition involves prolonged muscle contractions or abnormal postures that can lead to twisting and repetitive movements. It is typically associated with the effects of certain medications, particularly antipsychotics, and can result in significant discomfort and impairment of movement.

Focusing on the other options: spasmodic reactions refer more generally to involuntary muscle spasms or cramps, which may not necessarily involve the same level of distortion or impairment of voluntary movements as seen in dystonia. Neuropathic reactions are tied to nerve damage or dysfunction and can lead to sensations like pain or numbness rather than distorted movements. Hypertonic reactions involve increased muscle tone, which can lead to stiffness but does not precisely capture the distorted and impaired nature found in dystonic reactions. Therefore, the definition and characteristics of dystonic reactions make it the most accurate answer to the question.