Hi,
Thank you for your query,
The information of MRI report you provided is a vague term and it is suggestive of some abnormality in the brain and it gives no clue to any diagnosis or a specific medical condition.
And pansinusitis means mucosal haziness and thickening of all sinuses and it is not related to the present clinical problem.
Consult the neurophysician with your child and with the reports and he will correlate the MRI findings and plan proper management.
Hope i have answered your query.

HI! acute intracranial conditions refer to several pathological condition like meningitis, encephalitis, brain abcess, intracranial hemorrhage, acute cerebral edema, contusion, venous sinus thrombosis, etc.
Pan sinusitis means inflammation of the para nasal sinuses which are air filled spaces in bone of skull and face due to infection either viral, bacterial or fungal.
As you have complained about seizure with history of flu with pan sinusitis, then i want to tell you that flu involve inflammation of upper respiratory tract which can then lead to inflammation of the para nasal sinuses which can then lead to intracranial involvement directly leading to meningitis, encephalitis or even brain abcess due to secondary bacterial infection or it can lead to lateral sinus thrombosis through acute middle ear infection(acute otitis media).Seizure is mainly caused by mass effect in the cranium which may be due to several causes as mentioned above.
To reach the proper diagnosis you should go for biochemical cytological and culture examination of CSF,routine blood examination including TLC, DLC,Hb, platelets count and then you should follow your neurologist for the proper management and later on you can also consult an ENT specialist for the prevention of sinusitis in future.