Differential Diagnosis for Sudden Clumsiness and Working Memory Issues in a 20-Year-Old Male
Single Most Likely Diagnosis
- Post-Infectious Encephalitis or Encephalopathy: This condition can occur after a viral illness, leading to inflammation of the brain, which may cause symptoms like clumsiness and working memory issues. The normal brain imaging (CT, MRI, PET) does not rule out this diagnosis, as some forms of encephalitis may not show abnormalities on these tests.
Other Likely Diagnoses
- Viral Meningitis: Although the brain imaging is normal, viral meningitis can cause symptoms such as clumsiness and cognitive issues. The swollen lymph nodes on CT support a recent viral infection.
- Acute Disseminated Encephalomyelitis (ADEM): ADEM is a rare autoimmune disease triggered by a viral infection, which can cause a range of neurological symptoms, including clumsiness and cognitive problems. Normal brain imaging at the onset does not exclude this diagnosis, as changes may appear later.
- Toxoplasmosis or Other Infectious Diseases: Reactivation of latent infections like toxoplasmosis, especially in immunocompetent individuals, can be rare but should be considered, especially if there's a history of exposure.
Do Not Miss Diagnoses
- Central Nervous System (CNS) Lymphoma: Although rare, CNS lymphoma can present with cognitive decline and neurological symptoms. It's crucial to monitor and possibly repeat imaging studies, as initial scans might be normal.
- Subacute Sclerosing Panencephalitis (SSPE): A rare but fatal condition caused by a persistent measles virus infection. It presents with cognitive decline, seizures, and myoclonus, often years after the initial measles infection.
- Creutzfeldt-Jakob Disease (CJD): A prion disease that can present with rapid cognitive decline, ataxia, and myoclonus. It's essential to consider, despite its rarity, due to its fatal outcome.
Rare Diagnoses
- Hashimoto's Encephalopathy: A rare condition associated with Hashimoto's thyroiditis, presenting with cognitive decline, seizures, and neurological symptoms. Thyroid function tests would be abnormal.
- Anti-NMDA Receptor Encephalitis: An autoimmune disease that can cause psychiatric symptoms, cognitive decline, and neurological deficits. It's more common in young women but can occur in men.
- Neurosyphilis: Can present with a wide range of neurological symptoms, including cognitive decline and clumsiness, especially in the tertiary stage. Screening for syphilis is essential, given its increasing incidence.