Differential Diagnosis

The patient's presentation suggests a complex neurologic disorder. The following differential diagnoses are considered:

• Single most likely diagnosis
  • Frontotemporal dementia (FTD): The combination of apraxia, aphasia, selective mutism, and palmomental reflex suggests a frontal lobe disorder. FTD is a group of neurodegenerative diseases that affect the frontal and temporal lobes, leading to changes in personality, behavior, and language.
• Other Likely diagnoses
  • Alzheimer's disease: Although the patient's age is not specified, Alzheimer's disease is a common cause of dementia and can present with aphasia, apraxia, and gait disturbances.
  • Vascular dementia: The presence of patellar hyperreflexia and a wide-based gait suggests a possible vascular component, which could be contributing to the patient's cognitive decline.
  • Traumatic brain injury: A history of trauma could have led to the patient's current neurologic state, including aphasia, apraxia, and gait disturbances.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Creutzfeldt-Jakob disease: This rare, degenerative disorder can present with rapid cognitive decline, aphasia, and gait disturbances. It is essential to consider this diagnosis due to its poor prognosis and potential for transmission.
  • Brain tumor: A space-occupying lesion, such as a tumor, could be causing the patient's symptoms, including aphasia, apraxia, and gait disturbances.
  • Infectious encephalitis: Certain infections, such as herpes simplex encephalitis, can cause severe neurologic symptoms, including aphasia, apraxia, and altered mental status.
• Rare diagnoses
  • Primary progressive aphasia: A rare neurodegenerative disorder characterized by gradual decline in language abilities, which could be contributing to the patient's aphasia and selective mutism.
  • Corticobasal degeneration: A rare neurodegenerative disorder that can present with apraxia, aphasia, and gait disturbances, often with a prominent alien limb phenomenon.

Next Steps in Diagnostic Evaluation

To further evaluate the patient, the following steps are recommended:

1. Imaging studies: Obtain a brain MRI or CT scan to rule out structural lesions, such as tumors or vascular malformations.
2. Laboratory tests: Conduct routine laboratory tests, including complete blood count, electrolyte panel, and liver function tests, to rule out systemic causes of cognitive decline.
3. Lumbar puncture: Consider a lumbar puncture to evaluate for infectious or inflammatory causes of encephalitis.
4. Neuropsychological testing: Perform a comprehensive neuropsychological evaluation to assess the patient's cognitive function and identify areas of strength and weakness.
5. Genetic testing: Consider genetic testing for frontotemporal dementia and other neurodegenerative disorders, especially if there is a family history of similar conditions.