Final answer:
The described symptoms following the start of antipsychotic medication point to Neuroleptic Malignant Syndrome (NMS), which is a severe and life-threatening reaction to such drugs.
Step-by-step explanation:
The symptoms described particularly muscular rigidity, altered mental status, and autonomic dysfunction following the initiation of antipsychotic medication are indicative of Neuroleptic Malignant Syndrome (NMS). This is a severe reaction to antipsychotic drugs, which are typically used to treat psychiatric conditions like schizophrenia. Antipsychotic medications work by blocking dopamine receptors, but this can lead to decreased dopamine neurotransmission in the brain, sometimes resulting in movement disorders and symptoms similar to Parkinson's disease. NMS is a rare but life-threatening condition characterized by the rapid onset of fever, muscle rigidity, altered mental status, and autonomic dysfunction after starting neuroleptic drugs.