Differential Diagnosis
- Single most likely diagnosis
- Serotonin Syndrome: This condition is highly likely given the patient's recent reduction in Prozac (fluoxetine) dose and the presence of symptoms such as altered mental status (AMS), stiffness, hyper-reflexia, and clonus. The improvement with diazepam also supports this diagnosis, as benzodiazepines are often used to manage symptoms of serotonin syndrome.
- Other Likely diagnoses
- Akathisia: This is a possible diagnosis given the patient's history of schizophrenia and the use of antipsychotic medications. Akathisia can cause restlessness, stiffness, and discomfort, which might align with some of the patient's symptoms. However, the presence of clonus and significant improvement with diazepam makes serotonin syndrome more likely.
- Neuroleptic Malignant Syndrome (NMS): Although the patient was discontinued from quetiapine, NMS could still be considered, especially with symptoms like stiffness and altered mental status. However, the absence of fever and the improvement with diazepam make this less likely compared to serotonin syndrome.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Meningitis or Encephalitis: These conditions can present with altered mental status and stiffness, and it's crucial to rule them out due to their potential severity and need for immediate treatment. Although less likely given the context, they cannot be missed.
- Status Epilepticus: The presence of clonus could suggest a seizure disorder, and status epilepticus is a medical emergency that requires immediate intervention.
- Rare diagnoses
- Tetanus: This infection can cause stiffness and hyper-reflexia, but it is relatively rare and would typically be associated with a history of exposure or trauma.
- Wilson's Disease: A genetic disorder that can cause neurological symptoms, including stiffness and altered mental status, but it would be unusual for it to present acutely in this manner without prior symptoms.