Anatomic distribution of gadolinium contrast medium by high-resolution magnetic resonance imaging after peribulbar and retrobulbar injections.
OBJECTIVE
To examine the anatomic distribution of gadolinium contrast medium by high-resolution surface-coil magnetic resonance imaging after peribulbar and retrobulbar injection.


METHODS
Comparative case series in which 4 healthy volunteers were randomized to peribulbar (n = 2) or retrobulbar (n = 2) injection of gadolinium and lidocaine hydrochloride, 2%, without epinephrine. Magnetic resonance imaging was performed before injection and at 5 minutes and 90 minutes after injection.


RESULTS
The peribulbar injection technique resulted in contrast medium primarily in the extraconal space, with no gadolinium observed at the orbital apex; surprisingly, a small amount of contrast medium was observed in the pterygopalatine fossa immediately after peribulbar injection. The retrobulbar injection technique resulted in gadolinium signal diffusely enhancing the intraconal space, orbital apex, optic nerve sheath, and optic canal. The signal intensity was clearly observed in the cavernous sinus surrounding the cavernous portion of the internal carotid artery. A small amount of contrast medium was detected in the pterygopalatine fossa.


CONCLUSIONS
The retrobulbar injection technique localizes to the intraconal space, with access to intracranial and central nervous system structures via the optic canal, superior orbital fissure, and cavernous sinus. In contrast, the peribulbar injection technique produces a mostly extraconal distribution; however, intraconal solution may communicate with the central nervous system via the inferior orbital fissure and pterygopalatine fossa. This novel finding suggests that peribulbar anesthesia has a readily accessible route for central nervous system toxic effects. Magnetic resonance imaging with gadolinium contrast medium administration provides an important methodological advantage over previously described techniques and is a safe, reproducible, and superior method of orbital imaging.
Department of Ophthalmology and Hotel Dieu Hospital, Queen’s University, Kingston, Ontario, Canada. dalmeida@evolation-medical.com
David R P
DR
Almeida
Michel J
MJ
Belliveau
Thomas
T
Enright
Omar
O
Islam
Sherif R
SR
El-Defrawy
Jeffrey
J
Gale
D000328:Adult; D000772:Anesthesia, Local / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003287:Contrast Media / Q000493:pharmacokinetics*; D004058:Diffusion; D017352:Echo-Planar Imaging; D005260:Female; D005682:Gadolinium / Q000493:pharmacokinetics*; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008279:Magnetic Resonance Imaging; D008297:Male; D009407:Nerve Block / Q000379:methods; D009915:Orbit / Q000378:metabolism*; D014018:Tissue Distribution; D055815:Young Adult
D000779:Anesthetics, Local; D003287:Contrast Media; D008012:Lidocaine; D005682:Gadolinium