Acute Methicillin-resistant staphylococcus aureus sinusitis complicated by bacteremia, rapid intracranial spread and permanent vision loss

A 35-year-old male with a history of polysubstance abuse and untreated Hepatitis C presented with one week of facial, orbital and neck pain with fevers. Vital signs and laboratory studies were concerning for severe sepsis. Non-contrasted head computed tomography (CT) scan followed by brain magnetic resonance imaging (MRI) were obtained.

Non-contrast head CT scan showed diffuse mucosal thickening of paranasal sinuses (Panel A, arrow). Brain magnetic resonance imaging (MRI) revealed inflammatory changes of the bilateral orbits (Panel B, red arrows) with right globe traction (Panel B, orange arrow). Patient received empiric treatment but developed Methicillin-resistant Staphylococcus aureus bacteremia. Repeat head CT showed worsening paranasal opacification and jugular tubercle osteomyelitis. He underwent extensive endoscopic sinus surgery. Despite this, brain MRI showed infectious progression to cavernous sinus thrombosis (Panel C, circles), clival osteomyelitis, (Panel D, arrow), left prepontine abscess (Panel E, arrow) and right tentorial subdural empyema (Panel F, arrow). Course was further complicated by chorioretinal infarction and permanent vision loss. Patient’s infection subsequently improved and he was discharged with long-term antibiotics. On two-month follow-up, patient’s condition had markedly subsided. A brain MRI six months after initial presentation revealed resolution of the findings described above (Panel G).

The incidence of sinus infection caused by community-acquired MRSA has increased in recent years [1]. Most cases of sinusitis involve a viral or bacterial pathogen that causes an inflammatory response, thick mucus production and sinus obstruction. Ciliary dysfunction also results in stasis of mucus and engorgement of sinus mucosa. Acute sinusitis typically presents with purulent rhinorrhea, nasal congestion and facial pain/pressure/fullness for up to four weeks duration. Paranasal sinusitis may spread to adjacent structures and cause orbital cellulitis, the most common complication [2]. The risk of intracranial extension in hospitalized patients with sinusitis ranges from 3.7% to 11% with an associated 5%-10% mortality [3,4]. The most common intracranial complications are frontal abscess followed by meningitis, subdural empyema, cavernous sinus thrombosis and osteomyelitis [2]. The risk of morbidity and mortality of invasive MRSA infections has been reported to be 17%-32% [2,3]. Our patient suffered from a rare and devastating consequence of chorioretinal infarction from septic emboli and ophthalmic vein thrombosis which resulted in permanent vision loss in both eyes.

Imaging must be obtained when signs and symptoms suggestive of infectious spread beyond the paranasal sinuses are present (i.e. severe headache, periorbital edema and neurologic defects). Imaging plays a central role in determining the extent of infection, identifying underlying anatomic abnormalities and planning for surgical drainage. Contrast-enhanced CT is the preferred, initial imaging modality for evaluation of the sinuses and bony abnormalities. Characteristic findings on CT include sinus opacification, air-fluid levels, sinus wall displacement and mucosal thickening of >4 mm [5]. Brain MRI with and without contrast is more suited for the detection of soft tissue inflammation, tumors and intracranial complications (i.e. abscesses). In T1 images, mucosal thickening is usually isointense to soft tissue whereas in T2 images, mucosal thickening and fluid are typically hyperintense [6].

The gold standard for diagnosis is endoscopic aspirate and culture which was utilized in our case [7]. The mainstay of treatment for MRSA sinusitis with intracranial extension involves prompt initiation of intravenous antibiotics, early debridement of sinuses and surgical drainage of intracranial foci. Delay in surgical intervention has been associated with prolonged hospitalization [4]. This case highlights that clinicians must keep a low threshold for the aggressive treatment of sinusitis in patients with a history of polysubstance abuse to prevent excess morbidity and mortality. CT and MRI are indispensable to confirm the diagnosis, evaluate the extent of disease and formulate an effective treatment strategy.

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