Skull Normal Variants



Skull Normal Variants


Miral D. Jhaveri, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Skull Normal Variants



    • Arachnoid Granulations, Calvarium


    • Vascular Grooves


    • Venous Lakes


    • Emissary Veins


    • Parietal Thinning


    • Asymmetric Marrow, Petrous Apex


    • Asymmetric Foramina (Jugular, Ovale)


    • Aerated Clinoids


    • Accessory Sutures (e.g., Mendosal)


  • Hyperostosis Frontalis Interna


Less Common



  • Prominent Convolutional Markings


Rare but Important



  • Wormian Bones


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Important to recognize normal anatomic variations



    • These are “leave me alone” lesions


    • Should not be mistaken for real disease (e.g., metastases)


Helpful Clues for Common Diagnoses



  • Skull Normal Variants



    • Arachnoid Granulations, Calvarium



      • Sharply demarcated defect in inner table


      • Adjacent to/within dural venous sinuses


      • CSF density/intensity


    • Vascular Grooves



      • Usually inner table


      • Caused by meningeal arteries, veins


      • Outer table produced by superficial temporal artery branches


    • Venous Lakes



      • Round or oval configuration


      • Diploic venous channel can usually be traced into venous lakes


    • Emissary Veins



      • Connect meningeal veins/dural venous sinuses with pericranial (scalp) veins


      • Chiefly in frontal, parietal bones


    • Parietal Thinning



      • Elongated oval-shaped thinness


      • Upper part of parietal bone involved


    • Asymmetric Marrow, Petrous Apex



      • Non-pneumatized marrow hyperintense on T1WI


      • Opposite side pneumatized


  • Hyperostosis Frontalis Interna



    • Predominately inner table overgrowth


    • Usually bilateral, symmetrical


    • Frontal; usually stops at coronal suture


    • ± Orbital roofs, parietal bones


Helpful Clues for Less Common Diagnoses



  • Prominent Convolutional Markings



    • Brain pulsations → inner table depressions


    • Children > > adults

Aug 3, 2016 | Posted by in NEUROLOGY | Comments Off on Skull Normal Variants
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