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Skull Base & Orbit

Complications of Sinusitis: Is It Crossing a Wall?

Fellowship-level neuroradiology teaching by E. Brooke Schrickel, MD. Open this topic in the interactive reading room →

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Core clinical idea

When you see sinusitis, ask 'is this just sinusitis or is it crossing a wall?' — septum (preseptal vs postseptal), bony table, dura, or vessel wall. The crossing, not the mucosal disease, drives the report and the call: report the danger (drainable collection, optic nerve, subdural empyema, ICA/basilar pseudoaneurysm) because that is what the surgeon and ED act on.

Bottom line

Don't ignore the sinus disease — ask which wall it has crossed (septum, bone, dura, vessel) and report the danger that changes the operation.

Core workstation questions

  • Is the disease preseptal or postseptal — and if postseptal, is there a drainable collection or optic nerve compromise?
  • Does the history (diabetic, immunocompromised, child) demand I treat this as invasive/complicated until proven otherwise?
  • Has disease crossed a bone table or reached the dura — meningitis, epidural, or the can't-miss subdural empyema?
  • Where does this sit relative to the ICA/basilar and the cavernous/dural venous sinuses — infarct, occlusion, thrombosis, or pseudoaneurysm risk?
  • Am I being fooled by inspissated/fungal secretions that lost T2 signal — did I check pre-contrast T1 and the post-contrast extent?

What changes reporting / management

  • State which side of the orbital septum the disease is on; postseptal disease is the emergency.
  • Report a subperiosteal or orbital abscess and any optic nerve edema/compression — these change management to drainage.
  • For apex/cavernous disease, name the cranial nerve territory at risk (optic, III/IV/VI, V1, and V2 at the cavernous level).
  • Flag subdural empyema loudly and separately from a simple epidural collection — it is the high-morbidity/mortality intracranial complication.
  • When clival/sphenoid disease abuts the ICA or basilar, raise mycotic pseudoaneurysm and the SAH risk; suggest CTA/angiography.

Practical traps

  • Treating sinus disease as background and missing the wall-crossing complication.
  • Densely inspissated proteinaceous/fungal secretions lose T2 signal and can mimic clear aerated sinus — bright T1 and post-contrast extent reveal them.
  • Calling a sphenoid clear off T2 alone in a diabetic/immunocompromised host.
  • Reading a subdural empyema as if it were an epidural collection.
  • Missing angioinvasive disease tracking to the ICA/basilar with infarct or pseudoaneurysm.

Teaching pearls

  • Preseptal vs postseptal is the management hinge — one is antibiotics, the other can be an OR.
  • The bad history (diabetic, immunocompromised, child) lowers your threshold — look harder at orbit, apex, and bone.
  • Subdural empyema is the high-mortality intracranial complication — never bury it next to a simple epidural collection.
  • Inspissated/fungal secretions can go dark on T2 and mimic clear sinus — trust bright T1 and the post-contrast extent.
  • When disease abuts the ICA or basilar, think mycotic pseudoaneurysm — the fatal event is SAH, not the sinusitis.

Teaching visuals

Orbital complications of sinusitis — Chandler grades & the route inCoronal · sinus to orbit — which wall was crossed, and how far back12345Ethmoidthe sourcePreseptalfront of septumLamina papyraceathe wall crossedPostseptal orbitsubperiosteal / fatCHANDLER GRADESI Preseptal cellulitisanterior to septum — no orbitalsignsII Orbital cellulitispostseptal, diffuse — no abscessIII Subperiosteal abscesslamina vs periorbita — classicallymedialIV Orbital abscesswithin orbital fat — intraconalV Cavernous sinus thrombosisposterior spread via orbital veinsI = preseptal (medical)II–V = postseptal (urgent / surgical)The clinical hingeEthmoid sinusitis crosses the paper-thin LAMINA PAPYRACEA into the medial orbit — that breached wall is the route in.The make-or-break call is PRESEPTAL (Chandler I, anterior to the orbital septum, medical) vs POSTSEPTAL (II–V).Postseptal = proptosis, painful/restricted EOM, vision threat → urgent, often surgical. Subperiosteal abscess isclassically MEDIAL; posterior spread via orbital veins → cavernous sinus thrombosis (cranial-nerve signs, oftenbilateral).
Sinusitis — Which Wall Has It Crossed? (Septum · Bone · Dura · Vessel)

Source lectures

  • Orbital and Intracranial Complications of Sinusitis

Educational material for radiology residents and neuroradiology fellows. Nothing here drives individual patient care, and it contains no patient data.