Computed tomography (CT) cisternography is a minimally-invasive imaging technique used to visualize the intracranial CSF cisterns using iodinated contrast medium injected into the subarachnoid space.
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Indications
- detect and localize active CSF leaks through the skull base (CSF rhinorrhea or CSF otorrhea)
- evaluate intracranial arachnoid cysts for communication with surrounding subarachnoid space
- plan neurosurgery or radiotherapy, especially when MRI is not possible
Contraindications
- adverse reaction to iodinated contrast media
- severe coagulopathy or thrombocytopenia
- sepsis or localized infection at the lumbar puncture site
- compartmentalized increased intracranial pressure
- pregnancy
- recent myelography within previous 1 week
Procedure
Preprocedural evaluation
- obtain medical history relating to medications, allergies, seizures, and bleeding
- review any available spinal imaging
- consider holding medications that decrease seizure threshold
- consider holding anticoagulant and antiplatelet therapy
- obtain informed consent relating to the risk, benefits, and alternatives of the procedures
- evaluate need for moderate sedation or general anesthesia
- consider obtaining a non-contrast head CT
Equipment
- standard equipment for fluoroscopy-guided lumbar puncture
- tilt table with device to secure the patient
- contrast media approved for intrathecal use
- 10 mL syringe and needle
- CT scanner
Technique
- fluoroscopy guided lumbar puncture is performed
- optionally, opening pressure can be measured or CSF samples collected
- 3-10 mL of an iodinated non-ionic low-osmolar contrast agent is slowly instilled into the thecal sac under intermittent fluoroscopy
- the spinal needle is withdrawn
- the patient is tilted with foot-end elevation (Trendelenburg position) and intermittently imaged until the contrast column flows into the cervical spinal canal
- the table is returned to horizontal position and the head is flexed into neutral position under imaging to document flow of contrast into the basal cisterns
- CT is performed immediately in prone and/or supine positions; concurrent maneuvers that provoke an active CSF leak, such as head hanging or sneezing, can also be performed
Complications
- headache (common)
- radicular pain or paresthesia (transient)
- bleeding
- infection
- seizure