Acute intermittent porphyria, Rasmussen encephalitis, or both?

Area of Science:

• Neurology
• Immunology
• Metabolic Disorders

Background:

• Rasmussen encephalitis is a rare, autoimmune inflammatory disease affecting one cerebral hemisphere, leading to progressive neurological deficits.
• Acute intermittent porphyria (AIP) is a rare genetic metabolic disorder affecting the heme synthesis pathway, characterized by acute neurovisceral attacks.

Observation:

• A young woman presented with refractory epilepsy, diagnosed as Rasmussen encephalitis, with elevated anti-GluR3B and anti-NR2A antibodies.
• Seven years later, she was diagnosed with acute intermittent porphyria, experiencing severe abdominal pain, dark urine, and hyponatremia.
• Attempts to discontinue antiepileptic drugs like phenobarbital and valproate worsened seizures; however, a porphyria crisis led to phenobarbital discontinuation and subsequent right hemispheric atrophy.

Findings:

• The patient exhibited a complex interplay between autoimmune encephalitis and a metabolic disorder.
• The study suggests a potential link between porphyria and the development or exacerbation of Rasmussen encephalitis.
• Elevated autoantibodies against glutamate receptors were observed in the patient's serum and cerebrospinal fluid.

Implications:

• This case suggests that porphyria should be considered in the differential diagnosis of patients with intractable seizures and Rasmussen encephalitis.
• Investigating co-existing metabolic and autoimmune conditions is crucial for managing complex neurological disorders.
• The findings advocate for broader screening for porphyria in refractory epilepsy cases to improve patient outcomes.