Differential Diagnosis for Rasmussen Encephalitis Mimickers

Rasmussen encephalitis is a rare inflammatory neurological disease, characterized by seizures, hemiparesis, and encephalitis, predominantly affecting one hemisphere of the brain. Given its rarity and severity, distinguishing it from other conditions that mimic its symptoms is crucial. The differential diagnoses can be categorized as follows:

• Single Most Likely Diagnosis

  • Epilepsia Partialis Continua (EPC): This condition is characterized by continuous focal seizures and can mimic the seizure activity seen in Rasmussen encephalitis. The key distinguishing feature is the absence of the progressive inflammatory and degenerative changes typical of Rasmussen encephalitis.

• Other Likely Diagnoses

  • Stroke or Cerebral Vasculitis: Conditions that affect blood flow to the brain can cause symptoms similar to Rasmussen encephalitis, including seizures and hemiparesis. Imaging studies can help differentiate these conditions.
  • Tuberculous Meningoencephalitis: This infection can cause seizures, focal neurological deficits, and encephalitis, making it a potential mimic. However, the presence of systemic symptoms of tuberculosis and specific imaging findings can aid in differentiation.
  • Subacute Sclerosing Panencephalitis (SSPE): A rare chronic, progressive encephalitis that affects primarily children and young adults, caused by a persistent infection with the measles virus. It presents with a variety of neurological symptoms, including seizures.

• Do Not Miss Diagnoses

  • Central Nervous System (CNS) Lymphoma: Although rare, CNS lymphoma can present with seizures, focal neurological deficits, and encephalitis-like symptoms. Missing this diagnosis could lead to delayed treatment of a potentially curable malignancy.
  • CNS Infections (e.g., Herpes Simplex Encephalitis, Brain Abscess): These conditions require urgent treatment and can present with symptoms overlapping those of Rasmussen encephalitis, including seizures and altered mental status.
  • Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS): A mitochondrial disorder that can cause stroke-like episodes, seizures, and encephalopathy. The key feature is the presence of lactic acidosis and specific mitochondrial DNA mutations.

• Rare Diagnoses

  • Bickerstaff Brainstem Encephalitis: A rare inflammatory condition of the brainstem that can cause a variety of neurological symptoms. While it primarily affects the brainstem, it can sometimes mimic the encephalitis aspect of Rasmussen encephalitis.
  • Hashimoto's Encephalopathy: A rare condition associated with autoimmune thyroiditis, characterized by encephalopathy, seizures, and sometimes stroke-like symptoms. The presence of high levels of antithyroid antibodies is a key diagnostic clue.
  • Neurodegeneration with Brain Iron Accumulation (NBIA): A group of rare, inherited disorders characterized by progressive neurological deterioration and excessive iron accumulation in the brain. Some forms can present with seizures and focal neurological signs, although the primary features are dystonia, parkinsonism, and spasticity.