Cerebellar Atrophy



Cerebellar Atrophy


Gregory L. Katzman, MD, MBA



DIFFERENTIAL DIAGNOSIS


Common



  • Aging Brain, Normal


  • Encephalomalacia, NOS


  • Progressive Non-Familial Adult Onset Cerebellar Degeneration



    • Chronic Vertebrobasilar Insufficiency


    • Alcoholic Encephalopathy


    • Phenytoin (Dilantin) Use, Chronic


    • Paraneoplastic Syndromes


    • Lithium Intoxication


    • Radiation and Chemotherapy


    • Hypothyroidism


Less Common



  • Cerebellitis, NOS


Rare but Important



  • Multiple System Atrophy


  • Ataxia, Hereditary, NOS


  • Ataxia Telangiectasia


  • Cerebellar Atrophy, Hereditary, NOS


  • Congenital Vermian Hypoplasia (Mimic)


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Clinical history often more important in making diagnosis than imaging findings


Helpful Clues for Common Diagnoses



  • Aging Brain, Normal



    • 1 Brain volume (including cerebellum) with ↑ age



      • Relative ↑ CSF spaces


      • Selective atrophy of WM (not gray matter) predominates


    • “Successfully aging brain”: Thin periventricular high signal rim without white matter hyperintensities


    • May find focal/confluent periventricular white matter hyperintensities


  • Encephalomalacia, NOS



    • All etiologies appear as CSF replacing destroyed parenchyma due to



      • Post-ischemic loss of tissue following parenchymal hypoxic cell death


      • Post-traumatic loss from parenchymal irreversible traumatic insult


      • Post-inflammatory loss by irreversibly injured tissue


  • Progressive Non-Familial Adult Onset Cerebellar Degeneration



    • Chronic Vertebrobasilar Insufficiency



      • Vertebral artery stenosis, posterior circulation ischemia


      • Posterior circulation ischemia of hemodynamic or embolic etiology


      • Atrophy w/sulcal enlargement; DWI dark


    • Alcoholic Encephalopathy



      • Primary (direct) effects of EtOH = neurotoxicity → cortical/cerebellar degeneration & atrophy


      • Best clue: Disproportionate superior vermian atrophy


      • F-18 FDG PET: Significant decrease in whole-brain metabolism


    • Phenytoin (Dilantin) Use, Chronic



      • Dilantin vs. seizures as cause of atrophy debated


      • Dilantin induces organic cerebellar damage & may interfere w/intestinal absorption of folate causing folate deficiency → cerebellar atrophy


      • Seizures can cause cerebellar atrophy as cerebellum is very sensitive to hypoxia → cerebellar atrophy


      • Normal orientation & anisotropy of middle cerebellar peduncle & transverse pontine fibers


    • Paraneoplastic Syndromes



      • Remote neurological effect(s) of cancer, associated with extra-CNS tumors


      • Most common tumor: Small cell lung carcinoma


      • Manifestation of paraneoplastic encephalomyelitis associated w/cerebellar degeneration


    • Lithium Intoxication



      • Lithium is a neurotoxin with a particular affinity for the cerebellum


      • Atrophy of internal granule and Purkinje cell layers with dentate gliosis → neuronal loss and spongiosis


      • Preceded by neuroleptic malignant syndrome


    • Radiation and Chemotherapy



      • Injury may be divided into acute, early delayed injury, late delayed injury


      • Diffuse white matter injury or necrosis


      • Radiation → induces cryptic vascular malformations; blood products



    • Hypothyroidism



      • Best diagnostic clue: Symmetrical pituitary enlargement reversible with thyroid hormone replacement therapy


      • May see generalized atrophy; alternatively focal cerebellar vermis or olivopontocerebellar atrophy


      • ↓ Cerebral perfusion & metabolism


Helpful Clues for Less Common Diagnoses



  • Cerebellitis, NOS



    • Rare inflammatory syndrome typically occurring as primary infectious, post-infectious, post-vaccination, or idiopathic disorder


    • Bilateral diffuse hemispheric abnormalities are most common (73%)


    • Often results in moderate to severe atrophy


Helpful Clues for Rare Diagnoses



  • Multiple System Atrophy



    • Sporadic progressive neurodegenerative disorder of adult onset, unknown etiology


    • “Hot cross bun” sign: Cruciform pontine hyperintensity on T2WI


    • Impaired orientation/anisotropy of middle peduncle transverse pontine fibers


  • Ataxia, Hereditary, NOS



    • Example: Friedreich ataxia → cerebellar, spinal atrophy


    • Can be divided into autosomal dominant, autosomal recessive, X-linked, mitochondrial


    • Some etiologies (e.g., cerebrotendinous xanthomatosis) may have diffuse white matter T2 hyperintense lesions


  • Ataxia Telangiectasia



    • Progressive neurodegenerative disorder; onset in early childhood; 1 in 40,000


    • Multisystem disease → cerebellar ataxia, oculomucocutaneous telangiectasias, & susceptibility to certain infections and neoplastic processes


    • Purkinje cell loss, atrophy of dentate nuclei, diffuse spongy degeneration, multiple foci of coagulative necrosis w/calcification in white matter


  • Cerebellar Atrophy, Hereditary, NOS

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Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on Cerebellar Atrophy
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