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David R. Almeida, Michel J. Belliveau, Thomas Enright, Omar Islam, Sherif R. El-Defrawy, Jeffrey Gale; High-resolution Surface Coil Magnetic Resonance Imaging After Peribulbar And Retrobulbar Injections. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2186.
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Retrobulbar and peribulbar blocks are commonly used forms of anesthesia for ophthalmic surgical procedures; however, the precise anatomic localization of injected solution is unknown for each technique. We set out to examine the anatomic distribution of gadolinium contrast by high-resolution surface coil magnetic resonance imaging (MRI) after peribulbar and retrobulbar injection.
Comparative case series. Four eyes were randomized to either peribulbar (n=2) or retrobulbar (n=2) injection of gadolinium and lidocaine 2% without epinephrine. Serial MRI imaging with surface coil was performed to determine anatomic distribution.
Retrobulbar injection technique localizes to the intraconal space with central nervous system (CNS) access via the optic canal, superior orbital fissure, and cavernous sinus. Contrastingly, peribulbar administration produces a mostly extraconal distribution; however, a small amount of intraconal solution may communicate with the CNS via the inferior orbital fissure and pterygopalatine fossa.
We show the full extent of spread of anesthetic blocks and demonstrate the novel finding of pterygopalatine fossa extension, which provides a readily accessible route for CNS toxicity after peribulbar injection. Additionally, we highlight cavernous sinus involvement with the retrobulbar technique. MRI with gadolinium contrast administration provides an important methodological advantage over previous reports and is a safe, reproducible, and superior method of orbital imaging.
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