Bithalamic Lesions

Bithalamic Lesions

Nancy J. Fischbein, MD



  • 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


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

Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on Bithalamic Lesions

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