My whole premise was predicated on recommending OP not perform another procedure, so we are in agreement. Patients who are this medicalized and know just what to say often want further workup/treatment for something that did not happen or does not exist. PDPH is a clinical diagnosis and standard of care is conservative therapy followed by EBP -- patient's words against OP's. If it is clear that PDPH did not occur but the patient insists on getting an EBP or worked up, then sending the patient out of OP's practice for workup without an EBP is most protective.
Agreed that CT myelograms can cause PDPH, would not be preferable, and dural puncture should always be avoided if possible. It is notable institutions that perform this workup use 26G needles instead of 22-24G needles like in olden days. For a point of reference in OB anesthesia and C-sections, spinals, CSE, and DPE with 25G needles are performed uneventfully everyday for patients without pre-existing epidurals. Spinals with 25G needles are also performed everyday for hip and knee surgeries. Admittedly, PDPH is likely underdiagnosed in these populations.
Best option was to avoid CESI altogether, but OP is already past this point. Next best option is conservative therapy and for OP to not get talked into personally placing another needle in the patient. If push came to shove and the patient is insistent that PDPH occurred and is not being treated according to standard of care, then send out for workup.