Case Of the Month 11 – Answer

The patient initially presented with an eye infection which was diagnosed as endophthalmitis but then developed an acute stroke.  These are likely related and by focusing on this combination we can find the suspected diagnosis more easily.  Let’s look at endophthalmitis to start:

Endophthalmitis is inflammation of the intraocular space that is usually a result of infection, but it can be sterile if caused by toxic agents or retained material after ocular surgery.  It can be further divided into two types:¹

• Endogenous: Hematogenous spread from a distant source of infection through the bloodstream
• Exogenous: Direct inoculation from an outside source, usually as a complication from surgery, foreign body, or direct trauma

Given that this patient reports no trauma or recent instrumentation of the eye, we can assume she has endogenous endophthalmitis and can focus on identifying the index infection.

The development of the acute hemorrhagic stroke, if believed to be related to the diagnosis of endophthalmitis, also needs to be explained with an infectious cause.  In endogenous endophthalmitis, there must be some degree of bacteremia to cause significant hematogenous spread, and therefore this patient’s hemorrhage could potentially be secondary to a bleeding mycotic aneurysm.  Mycotic aneurysms arise from an infection in the wall of an artery which weakens the strength of the wall.  So in an attempt to apply Occam’s razor, we might be able to explain the entirety of this presentation on the hematogenous seeding of an infection.  By using the physical exam findings, labwork results, and the etiologies of mycotic aneurysms and endogenous endophthalmitis, a likely diagnosis can be reached.

This patient presented with a case of endocarditis, complicated by endophthalmitis and intracranial mycotic aneurysmal rupture.  She has a grade 3/6 murmur on exam and two sites which we may assume have been seeded through bacteremia.  Endocarditis can present with all these signs and symptoms and can neatly tie this entire presentation together.

One series identified endocarditis as the cause of bacterial endogenous endophthalmitis in 40% of cases in the US².  Elsewhere in the world, seeding from liver abscesses can account for up to 60% of cases³.  It is therefore reasonable to suspect endocarditis as the index infection in a case that occurs in the US⁴.

25 to 50% of patients with endocarditis are predicted to have some type of septic embolization, however only about 1 to 5% eventually develop mycotic aneurysms⁵.  Intracranial arteries are more commonly involved than other sites.  One study found that about 4% of patients with endocarditis undergoing preop evaluation with intracranial imaging had mycotic aneurysms⁶.  So although these are rare, mycotic aneurysms should raise a high suspicion for undiagnosed endocarditis in any patient.

Aside from what has already been done, performing a bedside ultrasound may help confirm the presence of vegetations or valvular dysfunction. However, TEE is more accurate in identifying valvular lesions.  Blood cultures drawn from multiple sites and broad-spectrum systemic antibiotics are paramount in the treatment of mycotic aneurysms and endocarditis.  This is in addition to the intravitreal injections the patient will receive.  Further inpatient workup will involve assessing valvular competency and the presence of cardiac abscesses/fistulas and identifying the primary organism in an attempt to determine whether valvular surgery is indicated as well.

References:

1. Egan DJ, Peak DA, Peters JR. http://emedicine.medscape.com/article/799431-overview
2. Okada AA, Johnson RP, Liles WC, D’Amico DJ, Baker AS. Endogenous bacterial endophthalmitis. Report of a ten-year retrospective study. Ophthalmology. 1994;101(5):832.
3. Wong JS, Chan TK, Lee HM, Chee SP. Endogenous bacterial endophthalmitis: an east Asian experience and a reappraisal of a severe ocular affliction. Ophthalmology. 2000;107(8):1483.
4. Eran Pras, Alexander Rubowitz, Joseph R Ferencz, Judith Raz, Y. Rotenstreich, Ehud I. Assia. Endogenous endophthalmitis as the leading sign of endocarditis. Annals of Ophthalmology, June 2001, Volume 33, Issue 2, pp 148-150
5. Baddour LM, Wilson WR, Bayer AS, Fowler VG Jr, Tleyjeh IM, Rybak MJ, Barsic B, Lockhart PB, Gewitz MH, Levison ME, Bolger AF, Steckelberg JM, Baltimore RS, Fink AM, O’Gara P, Taubert KA, American Heart Association Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease of the Council on Cardiovascular Disease in the Young, Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and Stroke Council. Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications: A Scientific Statement for Healthcare Professionals From the American Heart Association. Circulation. 2015;132(15):1435.
6. Monteleone PP, Shrestha NK, Jacob J, Gordon SM, Fraser TG, Rehm SJ, Bajzer CT, Kapadia SR, Pettersson GB, Lytle BW, Blackstone EH, Shishehbor MH. Clinical utility of cerebral angiography in the preoperative assessment of endocarditis. Vasc Med. 2014 Dec;19(6):500-6. Epub 2014 Oct 31.