Final answer:
Neuroleptic malignant syndrome usually starts with agitation before muscle rigidity, while Parkinson's disease typically begins with muscle rigidity. Parkinson's is characterized by symptoms such as muscle tremor, rigidity, and slowness of movement.
Step-by-step explanation:
In patients with neuroleptic malignant syndrome (NMS), there is a prodrome of agitation and excitement before the onset of muscle rigidity while Parkinson's disease typically begins with muscle rigidity. Parkinson's disease is a degenerative disorder affecting the muscular system and movement, characterized by muscle tremor, muscle rigidity, slowness of movement, and postural instability. The most common initial symptom of Parkinson's disease is a tremor, which is particularly noticeable in a limb at rest and disappears with voluntary movement or during sleep. As the disease advances, patients often develop difficulty walking and can experience dementia and depression.