Paracentral Acute Middle Maculopathy
Title: Paracentral Acute Middle Maculopathy
Authors: Caitlynn Cooper, MS4, Jeff Pettey, MD, Marissa Larochelle, MD
Keywords/Main Subjects: Paracentral Acute Middle Maculopathy (PAMM)
CORE Category: https://morancore.utah.edu/section-12-retina-and-vitreous/
Diagnosis: Paracentral Acute Middle Maculopathy, PAMM
Description of Case: This case study focuses on a 75-year-old woman with a history of hypertension, migraine headaches, and polymyalgia rheumatica. Her ocular history included right eye posterior vitreous detachment, bilateral posterior capsular opacifications, and bilateral upper and lower Meibomian gland dysfunction. She presented to the clinic with new onset blurred vision which she noted immediately after an airboat ride. She reported a new “blind spot” to her right eye. A macular optical coherence tomography (OCT) of the right eye revealed a hyper-reflective band-like lesion at the level of the inner nuclear layer (INL).
Figure 1: Macular OCT of the right eye on initial presentation displays the PAMM lesion, seen as a hyper-reflective band-like area at the level of the inner nuclear layer.
Figure 2: Macular OCT 6 months later shows mild disruption of the architecture and atrophy of the inner retina in the area of the prior PAMM lesion.
Definition: PAMM is an OCT phenomenon that represents underlying retinal ischemia. It clinically presents as a patient with a persistent scotoma.
Epidemiology: PAMM was first documented in 2013 by Sarraf et al. As a new diagnosis, understanding is still evolving. It does appear that it occurs more frequently in ages 50-70. However, very little is understood about incidence/prevalence in the population or patient demographics.
Etiology: While the cause of PAMM is not fully understood, it is considered likely that an ischemia of the deep retinal capillary plexus leads to an infarct of the inner nuclear layer. There are potential comorbidities that may be causative of PAMM including hypercoagulability, hypotension, and systemic cardiovascular disease. PAMM has also been reported to occur at a high rate with other retinal pathologies including retinal vascular occlusions, diabetic retinopathy, retinal vasculitis, sickle cell retinopathy. However, there are cases of PAMM that occur independent of cardiovascular or hemodynamic risk factors. It has been hypothesized that acute, self-resolving PAMM may be independent of ischemia while persistent PAMM occurs as a result of an ischemic insult.
Clinical Presentation: PAMM tends to occur with an associated scotoma so patient’s visual fields may be affected. In addition, a drop in visual acuity may occur. On fundus exam, there may be a localized area of hypopigmentation.
Diagnosis/testing: PAMM is recognized by a band of hyper-reflectivity at the inner nuclear layer or outer plexiform layer on spectral domain optical coherence tomography (SD-OCT). Fundus photography may reflect PAMM via an area of whitening. Near-infrared reflectance imaging may display an area of hypo-reflectivity. Differentiating PAMM from cotton-wool spots may be difficult. Cotton-wool spots are appreciated as chalky on fundus photographs and their OCT hyper-reflectivity will be localized to the ganglion cell and superficial nerve fiber layers.
Disease course: A patient with PAMM will initially present with an acute onset paracentral scotoma. The lesions seen on SD-OCT will eventually resolve with atrophy of the inner nuclear layer. This area of atrophy leads to a persistent paracentral scotoma.
Management: There is currently no management for PAMM. However, since it occurs so frequently with cardiovascular disease, the patient should be screened for diseases that may be etiologies or comorbidities. Locally, one should screen for other retinal vessel occlusions. Systemically, screening should include hypertension, coagulopathies, diabetes, coronary artery disease, and vasculitidies.
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Faculty Approval by: Jeff Pettey, MD, Marissa Larochelle, MD
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