Table 1

Common differential diagnoses of paraneoplastic encephalitis

Common aetiologies in differential diagnosis of PNS
Vascular
Percheron artery occlusion
Infectious
HSV-1
VZV
HHV-6
Whipple disease
Listeria meningitis
Tuberculous meningitis
Creutzfeld-Jakob disease
Neurosyphilis
Toxic-metabolic
Uraemic encephalopathy
Hepatic encephalopathy
Septic encephalopathy
Wernicke-Korsakoff encephalopathy
Cancer and cancer therapy related
Primary CNS tumours
New CNS metastasis or known metastatic progression or leptomeningeal carcinomatosis
Complications of cranial radiation therapy (SMART syndrome)
Chemotherapy-related encephalopathy
Key differences
MRI features/cardiovascular risk factors present
Bilateral thalamic T2 FLAIR hyperintensities with diffusion restriction
MRI features
T2 hyperintense signal on MRI with presence of haemorrhagic necrosis of the affected area
Cerebellar oedema
Bilateral hyper intensity of hippocampus regions
Bilateral hyper intensity of hippocampus regions
Contrast enhancing ring lesions in the brainstem
Diffuse basal enhancement with enhancing exudates, hydrocephalus
DWI basal ganglia or cortical hyperintensities
Unilateral/bilateral mesiotemporal FLAIR hyperintensities on MRI. Exclusion with specific testing for syphylis
Serum metabolic profile and history are suggestive
MRI features
Normal or not specific
Normal or not specific
Wide range of findings from cortical-subcortical haemorrhages, ischaemia, to oedema of the basal ganglia
Normal to hyperintense FLAIR fo mammillary bodies
MRI features
Exclusion with MRI
Exclusion with MRI
Contrast enhancement of the leptomeninges on MRI
Reversible FLAIR cortical hyperintensities with contrast enhancement
Various findings depending on the chemotherapeutic agent used and type of encephalopathy
  • CNS, central nervous system; HHV-6, human herpes virus-6; HSV-1, herpes simplex virus-1; PNS, paraneoplastic neurological syndromes; SMART, stroke-like migraine attacks after radiation therapy; VZV, varicella zoster virus.