Bithalamic Lesions

Bithalamic Lesions
Nancy J. Fischbein, MD
DIFFERENTIAL DIAGNOSIS
Common
  • Arterial Ischemia
  • Venous Ischemia/Deep Venous Thrombosis
  • ADEM
  • Diffuse Astrocytoma/Gliomatosis Cerebri
Less Common
  • Hypoxic-Ischemic Encephalopathy, NOS
    • HIE, Term Neonate
    • Profound Hypoperfusion Injury, Adult
  • Acute Hypertensive Encephalopathy, PRES
  • Lymphoma, Primary CNS
  • Multiple Sclerosis
  • Vasculitis
  • Wernicke Encephalopathy
  • Osmotic Demyelination Syndrome
  • Encephalitis/Encephalopathy
    • Viral (Multiple Agents)
    • Acute Necrotizing Encephalopathy (ANE) of Childhood
Rare but Important
  • Creutzfeldt-Jakob Disease (CJD)
  • Paraneoplastic Syndromes
  • Inborn Errors of Metabolism
    • Krabbe Disease
    • Wilson Disease
    • GM1, GM with Gangliosidoses
  • Mitochondrial Disorders
  • Solvent Inhalation, Toxic Ingestion
  • Fahr Disease
  • Kernicterus
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
  • Reduced diffusion in bithalamic process: Artery of Percheron infarct; bilateral PCA infarcts; encephalitis; HIE; vasculitis; metabolic disorder; mitochondrial disorder
  • Bithalamic lesions with hemorrhage: Deep venous thrombosis; vasculitis; encephalitis
  • Symmetrical bithalamic lesions: Wernicke encephalopathy; osmotic myelinolysis; HIE; CJD; inborn errors of metabolism
Helpful Clues for Common Diagnoses
  • Arterial Ischemia
    • Often associated with vertebrobasilar disease, “top of the basilar” syndrome
    • Acute onset of symptoms, reduced diffusion
    • Artery of Percheron infarct: Occlusion of a common vascular trunk that arises from one P1 segment, supplies bilateral thalami
    • Infarction of midbrain often also present
  • Venous Ischemia/Deep Venous Thrombosis
    • Usually thrombosis of vein of Galen, straight sinus, bilateral internal cerebral veins
    • Edema, swelling with venous ischemia
    • Reduced diffusion, parenchymal hemorrhage with venous infarction
    • CTV or MRV useful to establish specific diagnosis
  • ADEM
    • Often affects thalami bilaterally
    • May cause swelling, T2 hyperintensity, variable enhancement
    • Usually associated with white matter (WM) lesions elsewhere in brain, with T2 high signal & variable gad enhancement
  • Diffuse Astrocytoma/Gliomatosis Cerebri
    • Bithalamic infiltration by neoplastic cells usually occurs with diffuse astrocytoma or gliomatosis cerebri
Helpful Clues for Less Common Diagnoses
  • Hypoxic-Ischemic Encephalopathy, NOS
    • Commonly affects bilateral thalami when profound
      • Diffuse thalamic injury in preterm neonates
      • Lateral thalamic injury in term neonates
    • Thalamic injury in adults usually accompanied by global severe injury to cortex, hippocampi, & basal ganglia
  • Acute Hypertensive Encephalopathy, PRES
    • Thalamic involvement typically occurs in patients who also have classic symmetrical parietooccipital T2 hyperintensity
    • Often bilateral, not necessarily symmetrical
    • T2 high signal, variable swelling; reduced diffusion, gad enhancement atypical
  • Vasculitis
    • Patchy T2 high signal & reduced diffusion
    • CTA or MRA possibly abnormal; catheter angio shows irregularity, narrowing
    • Primary angiitis of CNS vs. secondary (drug-induced, SLE, PAN, Wegener, etc.)
  • Wernicke Encephalopathy
    • T2 high signal in dorsal medial nucleus of thalamus
    • Enhancement usually absent; may show variably reduced diffusion
    • Associated midbrain, mamillary body abnormalities may be seen
  • Osmotic Demyelination Syndrome
    • Extrapontine myelinolysis (EPM) often accompanied by central pontine myelinolysis
    • EPM commonly affects thalamus; external capsule; putamen; caudate nucleus
    • Typically very symmetrical
  • Encephalitis/Encephalopathy
    • Many encephalitides may affect thalami: EBV, Japanese encephalitis; West Nile virus
    • Acute necrotizing encephalopathy (ANE): Affects infants, children; thalamic involvement common
      • Controversial if viral etiology vs. more likely immune-mediated or metabolic pathogenesis
Helpful Clues for Rare Diagnoses
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Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on Bithalamic Lesions

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