Thread by @NateWarnerMD

50yo F p/w acute onset fever, diarrhea. On exam is hypotensive and mildly confused. Sx started 2 days after return from Zambia. No malaria ppx. Smear w/ 30% P falciparum parasitemia. MICU concerned for cerebral malaria (CM). How can we confirm on #PhysicalExam ?#IDConsults

Cerebral malaria is defined by WHO as coma with peripheral parasitemia after other causes ruled out. In endemic regions this predominantly affects young kids due to immunologic naivety. Unfortunately, this defn is nonspecific as 40-70% of asymptomatic ppl may be parasitemic 2/

Pathophys of cerebral malaria is related to sequestration of parasitized RBCs in the CNS blood vessels...thanks to Hermann von Helmholtz’s invention of the ophthalmoscope in 1851 (with just a few updates from the original), we have a window to the vasculature of the CNS! 3/

Malaria retinopathy originally described in 1993 and shown to be the most specific test for cerebral malaria in young kids who die from cerebral malaria (1). Specificity of WHO defn = 61% versus 90% specificity when retinopathy dx’d by ophthalmologist w/ indirect fundoscopy!! 4/

Malaria retinopathy consists of 1. Retinal whitening (local ischemia in areas of high metabolic demand such as macula and temporal retina) 2. Vessel changes (orange appearance of retinal vessels) 3. Pale centered retinal hemorrhages (similar to Roth spots) and 4. Papilledema 5/

Our patient was treated with IV quinidine + doxy and parasitemia resolved over several days. She had hemorrhages (one of which with pale center) but no vessel changes or retinal whitening. Given the clinical context though, felt to be supportive of cerebral malaria. 6/

Caveats to this case: literature for retinopathy is primarily in young children rather than adults. This adult patient was not from endemic region so perhaps can extrapolate from children given immunologic naivety to Malaria in both. 7/

Additional caveat: quinidine no longer available in US. Artesunate must be obtained from the CDC in cases of cerebral malaria. Artesunate is the better drug anyway. 8/

Lastly, literature supporting malaria retinopathy was studied using indirect ophthalmoscopy which gives wider retinal view (versus direct) as most findings in malaria retinopathy are peripheral. This could be a barrier to more widespread use in resource-poor areas. 9/

I hope you all enjoyed this #tweetorial! In a critically ill patient returning from a malaria-endemic region, remember to look in the eyes (with indirect ophthalmoscope)! #IDConsults #PhysicalExam #MedEd #IDTwitter #IDMedEd 10/
@davidvanduin

Refs:
1. AmJTropMedHyg,75(5),2006, pp 790-797 (photos screenshot from this article)
2. Barrera et al. eLife 2018;7:e32208
3. Nature Medicine 10,143-145 (2004).
4. ARCH OPHTHALMOL/VOL 120, FEB 2002
5. cdc.gov/malaria/new_in…
6. veatchinstruments.com/about-ophthalm…
11/