Rasmussen syndrome may be difficult to diagnose in initial stages
when it may have no distinguishing features from other causes of focal
motor seizures. Other conditions to consider in the differential
diagnosis include:
Structural brain abnormality - especially if hemispheric and subtle on imaging (i.e. focal cortical dysplasia type 1)
Mitochondrial
disorders e.g. mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) or POLG-related disorders.