A 38-year-old woman with a history of bipolar I disorder, currently experiencing a manic episode with psychotic features, presents to the emergency department. She was brought in by her family due to increased agitation, disorganized speech, and aggression over the past 48 hours. Upon arrival, she received an intramuscular injection of haloperidol for acute behavioral control. Approximately 6 hours later, the nursing staff notes a significant change in her condition. She is now less agitated but appears obtunded, has a temperature of 39.5°C, a heart rate of 130 beats/min, and blood pressure of 160/100 mmHg. Physical examination reveals lead-pipe rigidity in all extremities, profound diaphoresis, and a mask-like facies with drooling. What is the most probable diagnosis and the immediate next step in management?

A 35-year-old woman, with a history of recurrent depressive episodes with psychotic features, was recently admitted to a general medical ward for stabilization of her mood and thought disorder. Three days prior, she was initiated on a standard dose of an antipsychotic medication. Over the past 12 hours, nursing staff noted a progressive change in her condition. She developed a fever, peaking at 39.8 C, accompanied by profound generalized muscular rigidity and significant diaphoresis. Her mental status has rapidly deteriorated from agitated confusion to marked obtundation. Vital signs are labile, with blood pressure fluctuating between 95/60 mm Hg and 180/100 mm Hg, and heart rate ranging from 110 to 140 beats per minute. Her current antipsychotic medication has been promptly discontinued, and aggressive supportive care including intravenous fluids and a bolus of intravenous lorazepam has been administered. Given the clinical presentation, what is the most likely diagnosis and the immediate definitive pharmacological intervention, considering potential complications?

A 45-year-old woman with a history of schizophrenia, recently initiated on an increased dose of her antipsychotic medication, presents to an urgent care facility with her family due to a rapidly progressing decline in her responsiveness over the past 12 hours. Her family reports she has become increasingly agitated, then stuporous, and is experiencing extreme body stiffness. On examination, her temperature is 40.5 C, heart rate 120 beats/min, blood pressure 190/115 mm Hg, and respiratory rate 24 breaths/min. She is minimally responsive to painful stimuli, with notable generalized "lead-pipe" muscle rigidity and profuse diaphoresis. Pupils are mid-dilated and reactive. Her complete blood count shows an elevated white blood cell count. What is the most likely diagnosis and the immediate definitive pharmacological intervention for this patient's critical condition?

A 48-year-old woman with a chronic psychotic disorder, who recently had her oral antipsychotic regimen adjusted to include a higher dose of haloperidol, is brought to the urgent care center by her family. For the past day, she has been increasingly withdrawn and appears disoriented. Her family reports a rapid onset of muscle stiffness, difficulty walking, and a fever that has not responded to antipyretics. She has been minimally responsive to verbal commands. On examination, her temperature is 39.8 C, blood pressure is 155/105 mm Hg, pulse is 125 beats/min, and respirations are 24/min. She exhibits generalized lead-pipe rigidity, diaphoresis, and a masked facies. Deep tendon reflexes are normoactive, and no clonus is noted. Laboratory studies are ordered. Which of the following represents the most probable diagnosis and the cornerstone of immediate management for this patient's critical condition?

A 42-year-old female presents to the emergency department accompanied by her family, who report a rapid decline in her condition over the past 24-48 hours. She exhibits profound confusion, mutism, and fluctuating levels of consciousness. Her family mentions she was recently prescribed olanzapine, a second-generation antipsychotic, about 10 days ago for managing new-onset behavioral disturbances. On assessment, her temperature is 39.8°C, blood pressure is 165/95 mmHg, heart rate is 120/min, and respiratory rate is 28/min. Physical examination reveals generalized "lead-pipe" rigidity, particularly pronounced in the limbs, and diminished deep tendon reflexes, along with profuse sweating and facial flushing. Laboratory results indicate elevated creatine kinase, leukocytosis, and acute kidney injury. Intravenous (IV) access is obtained, and balanced crystalloid fluids are started. Cool mist and fans are applied to the patient. What is the most likely diagnosis and the most critical initial management step?

A 35-year-old woman with a history of chronic psychiatric illness, recently started on a new medication to manage her symptoms, presents to the emergency department. Her family reports that over the past 12 hours, she has become progressively withdrawn and stiff, with episodes of agitation and unresponsiveness. Upon examination, her temperature is 40.2 °C, blood pressure is 185/105 mmHg, heart rate is 120 beats/min, and respiratory rate is 22 breaths/min. She exhibits generalized lead-pipe rigidity, profuse sweating, and fluctuating levels of consciousness. Her pupils are mid-dilated and reactive to light, and deep tendon reflexes are diminished. There are no signs of meningeal irritation. Considering these findings, what is the most likely diagnosis and the immediate next step in management?

A 32-year-old woman is admitted to the hospital from an outpatient psychiatric clinic after her family noted a rapid decline in her condition over the past 24 hours. She had recently been initiated on a new medication for managing severe agitation and disordered thought patterns. Her family reports she has become increasingly unresponsive, experiencing significant tremors, and profuse sweating. On arrival, she is obtunded and appears acutely unwell. Her vital signs include a temperature of 40.5 C, blood pressure 180/100 mmHg, pulse 125/min, and respiratory rate 24/min. Physical examination reveals generalized lead-pipe rigidity, diminished reflexes, and an absence of nuchal rigidity. The skin is warm and diaphoretic. Cardiac and pulmonary examinations are unremarkable. Given this clinical presentation and initial laboratory findings, what is the most likely diagnosis, and what is the immediate priority in its management?

A 48-year-old male is brought to an urgent care center by his family due to escalating bizarre behavior and physical changes over the past 36 hours. He has a known history of bipolar disorder with psychotic features, managed previously with various oral antipsychotics, but recently discontinued his medication due to perceived lack of efficacy. Three days prior, following a severe manic episode with aggressive outbursts, he was involuntarily admitted and initiated on a new regimen of intramuscular fluphenazine. His family reports that initially, he seemed calmer, but then developed a peculiar "stiffening" of his limbs and became increasingly disoriented. They also noted profuse sweating despite feeling cool to the touch. Upon arrival, he is restless but minimally responsive to verbal commands. His oral temperature is 39.5°C, blood pressure 160/95 mmHg, heart rate 135 bpm, and respiratory rate 28 breaths/min. Physical examination reveals lead-pipe rigidity throughout all extremities, generalized hypertonia, and some cogwheeling. His skin is hot and clammy, and he exhibits prominent diaphoresis. He appears to fixate on unseen objects and occasionally moans. His reflexes are generally diminished. Given the evolving clinical picture, what is the most likely diagnosis and the immediate definitive therapeutic intervention required?