metrizamide and Optic-Nerve-Diseases

Between the optic nerve and its sheath is a small, CSF-filled space that communicates with the subarachnoid space of the brain. A technique for the radiographic opacification of the optic nerve subarachnoid space following the intrathecal injection of metrizamide was investigated in 8 dogs. The technique enabled indirect visualization of the optic nerves from the optic chiasm to the eyeball and of structures within the subarachnoid basal cisterns of the brain, including the optic chiasm, hypophysis, and blood vessels of the cerebral arterial circle. Displacement and obstruction of the optic nerve subarachnoid space were demonstrated after surgically creating optic nerve lesions to simulate orbital tumors and trauma. The technique was found to be safe, effective, and advantageous over other techniques currently available for the visualization of these structures.

Topics: Animals; Arachnoiditis; Dog Diseases; Dogs; Iodine; Metrizamide; Optic Nerve; Optic Nerve Diseases; Radiography; Subarachnoid Space

The subarachnoid space continues into the orbit as part of the optic nerve sheath. This space varies in size but is usually tiny. Occasionally, prominent (one case in our experience) enhancement of the optic nerve as part of metrizamide computed tomography (CT) cisternography is seen on transverse and coronal scans presumably because of a patulous optic subarachnoid space. In five cases, we have appreciated minimal enhancement of optic nerves with metrizamide only by close comparison of CT numbers with base-line scans. One of these patients had a tiny meningioma removed successfully from the optic sheath, with return to normal vision of a previously blind eye.

Topics: Adult; Cerebrospinal Fluid Rhinorrhea; Cranial Nerve Neoplasms; Female; Humans; Injections, Spinal; Meningioma; Metrizamide; Middle Aged; Optic Nerve; Optic Nerve Diseases; Radiographic Image Enhancement; Tomography, X-Ray Computed