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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