Internal carotid artery dissection manifesting as paracentral acute middle maculopathy: a case report and review of literature

Abstract

AbstractSection Background

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Paracentral acute middle maculopathy (PAMM), which is a microvasculopathy characterized by ischemic injury to the middle retinal layers, typically presents with acute-onset paracentral scotomas, PAMM is often monocular, and may lead to permanent visual field defects.

AbstractSection Case presentation

In this case report, we present a patient with acute paracentral acute middle maculopathy (PAMM) due to internal carotid artery dissection (ICAD), without any other systemic symptoms. A 37-year-old male presented with acute visual impairment in his left eye. Cerebral angiography confirmed ICAD. His visual acuity and function significantly improved following internal carotid artery angioplasty and thrombectomy.

AbstractSection Conclusions

This case underscores the need for ophthalmologists to maintain heightened awareness of potential carotid pathology in patients presenting with PAMM. Concurrently, neurologists should closely monitor retinal perfusion status in patients with ICAD. Multidisciplinary collaboration and precision medicine strategies are pivotal for optimizing patient outcomes.

Background

Paracentral acute middle maculopathy (PAMM) is a disorder characterized by acute-onset paracentral scotomas affecting the middle retinal layers of the macula. It was first described and coined by Sarraf [1] in 2013.

Carotid artery dissection (CAD) refers to a tear in the intima of the cervical arteries, allowing blood to enter the vessel wall and separate the intima from the media, resulting in an intramural hematoma and/or aneurysmal dilation. Broadly speaking, CAD encompasses dissections of both the carotid and vertebral arteries [2]. CAD represents the most common cause of ischemic stroke in young and middle-aged adults, accounting for approximately 20% of ischemic strokes in patients under 45 years of age, with a higher prevalence among males [3]. Internal carotid artery dissection (ICAD) is the most frequent subtype of CAD.

We present a case of a 37-year-old previously healthy male who developed acute-onset visual impairment in his left eye. He had no history of systemic vascular disease. The diagnosis of ICAD was established using cerebral angiography. The patient’s visual acuity and function demonstrated significant improvement following treatment. This case highlights the intricate relationship between systemic vascular pathology and retinal microvascular compromise, underscoring clinical physicians should include internal carotid artery dissection in the differential diagnosis of PAMM.

Case presentation

A 37-year-old male presented to our hospital on March 12, 2025, with a 24-h history of acute visual impairment in his left eye. The symptoms began abruptly at 8:00 on March 11, 2025, without discernible precipitating factors. The patient denied associated limb numbness or weakness, slurred speech, or dysphagia. As symptoms persisted, he sought evaluation at a local ophthalmology department. Fundus examination revealed no significant abnormalities, and a provisional diagnosis of “left central retinal artery occlusion (CRAO)” was formulated. He received unspecified treatment without symptomatic improvement.

The patient reported no significant past medical history, including hypertension, diabetes mellitus, hyperlipidemia, coronary artery disease, or atrial fibrillation. He denied tobacco or alcohol use and reported no relevant family history.

Ocular Examination:

• Extraocular movements: Full and normal.

• Best-corrected visual acuity (BCVA) (Snellen): Right eye, 20/20; Left eye, 20/1000.

• Intraocular pressure: Right eye, 15.1 mmHg; Left eye, 14.3 mmHg.

• Pupils: Right pupil demonstrated a brisk direct light reflex. A relative afferent pupillary defect (RAPD) was present in the left eye (+).

• Anterior segment (lens and vitreous): Clear bilaterally.

• Fundus examination: Fundus photography reveals parafoveal retinal whitish edema (Fig. 1A).

  Fig. 1

  

  Left Eye: A Color fundus photograph: parafoveal retinal whitish edema (within the red circle). B Optical coherence tomography (OCT): Revealed a discontinuous hyperreflective band within the inner nuclear layer (INL) at the fovea (indicated by the red arrow). C Optical coherence tomography angiography (OCTA): Demonstrated a fern-like pattern in the deep vascular plexus surrounding the macula (within the red circle). D Near-infrared reflectance (NIR) image: Showed well-defined, grayish-black lesions in the parafoveal region (marked by the red arrow). (1 Month Post-procedure) E Color fundus photograph: No significant abnormalities. F Optical coherence tomography (OCT): Showed focal areas of thinning within the INL at the fovea(marked by the red arrow). G Optical coherence tomography angiography (OCTA): Demonstrated regression of the previously observed fern-like pattern in the deep vascular plexus surrounding the macula (Fig. 1 C) (within the red circle)

• Optical coherence tomography (OCT): Revealed a discontinuous hyperreflective band within the inner nuclear layer (INL) at the fovea (Fig. 1B).

• OCT angiography (OCTA): Demonstrated a fern-like pattern in the deep vascular plexus surrounding the macula (Fig. 1C).

• Near-infrared reflectance imaging: Showed well-defined, grayish-black lesions in the parafoveal region (Fig. 1D).

Right eye: All examinations were normal.

Given the patient’s young age, lack of significant systemic history or risk factors, he was referred to the Neurology department. Emergency cranial diffusion-weighted imaging (DWI) revealed no acute abnormalities. Neurological examination was unremarkable.

Laboratory Findings: White blood cell count, 14.17 × 10⁹/L; neutrophil count, 11.59 × 10⁹/L; prothrombin time (PT), 13.60 s; activated partial thromboplastin time, 23.70 s; and other systemic laboratory tests, within normal limits.

Emergency digital subtraction angiography (DSA) of the cerebral vessels was performed. DSA findings included: Left common carotid artery injection, dissection at the origin of the ICA with contrast stagnation, and observed multiple dark red thrombi. A string sign was noted in the C3 segment. Slow flow in the left anterior cerebral artery (ACA) and middle cerebral artery (MCA). Poor opacification of the left ophthalmic artery.

The patient subsequently underwent left ICAD angioplasty and left internal carotid artery thrombectomy performed. Final angiography demonstrated: Thrombolysis in cerebral infarction grade 3 flow in the left MCA and ACA. No contrast extravasation or residual thrombus. Excellent opacification of the left ophthalmic artery (Fig. 2). Further history-taking revealed that the patient frequently rotates the neck extensively to relieve neck discomfort.

Fig. 2

Digital Subtraction Angiography (DSA) and Endovascular Intervention. A Dissection at the origin of the internal carotid artery (ICA) with contrast stagnation (arrow) (marked by the red arrow). B Post-stent placement: Improved flow in the ICA (marked by the red arrow). C Post-stent placement: Excellent opacification of the left ophthalmic artery (arrow) (marked by the red arrow)

Final diagnoses: Left ICAD and left PAMM.

Follow-up (1 month later):

• BCVA(Snellen): Right eye, 20/20; Left eye, 20/33.

• Fundus examination: No significant abnormalities (Fig. 1E).

• OCT: Showed focal areas of thinning within the INL at the fovea (Fig. 1 F).

• OCTA: Demonstrated regression of the previously observed fern-like pattern in the deep vascular plexus surrounding the macula (Fig. 1G).

Discussion

This case report describes a 37-year-old male patient with a rare presentation of PAMM secondary to ICAD. As the patient solely presented with sudden vision loss without ocular pain on movement, orbital tenderness, or systemic symptoms, he was initially evaluated at a local ophthalmology department and tentatively diagnosed with “CRVO.” Probably, it was simply a placeholder diagnosis for profound, acute vision loss of presumed vascular origin. The typical fundoscopic findings in the acute phase of CRAO include retinal cloudiness and swelling (with pronounced pallor in the posterior pole), a “cherry-red spot” at the macula, attenuated retinal arteries, and a normal optic disc [4]. Fundoscopic examination in ocular ischemic syndrome (OIS) may reveal narrowed retinal arteries, dilated but non-tortuous retinal veins, retinal hemorrhages, optic disc swelling, and severe retinal edema. Slit-lamp examination may additionally demonstrate anterior segment ischemia, aqueous flare, iridocyclitis, and neovascular glaucoma [5]. These retinal findings vary significantly from those in the present case. Moreover, ophthalmic imaging performed the following day at our hospital indicated findings consistent with PAMM. Laboratory results revealed an elevated white blood cell count of 14.17 × 10⁹/L and an elevated neutrophil count of 11.59 × 10⁹/L. Although no systemic signs of infection were observed, the patient was diagnosed with ICAD. The leukocytosis is likely a nonspecific, expected response resulting from stress hormone release and a robust sterile inflammatory reaction due to acute vascular wall injury—a presentation consistent with the underlying pathophysiology.

PAMM, which is a microvasculopathy characterized by ischemic injury to the middle retinal layers, typically presents with acute-onset paracentral scotomas, primarily affecting the INL and outer plexiform layer. This manifests as discontinuous or continuous hyperreflective bands on OCT. Sridhar et al. [6] classified PAMM lesions into three morphological types: arteriolar, globular, and fern-like. PAMM is often monocular, acute in onset, typically follows a natural history characterized by acute, progressive, and chronic phases. PAMM may lead to permanent visual field defects [1]. The lesions can be subtle and are prone to being overlooked. While PAMM is now widely accepted as an ischemic condition of the deep retinal capillary plexuses, the full spectrum of underlying systemic and local triggers is still being elucidated [1, 7]. Current research suggests that the pathogenesis of PAMM is primarily associated with focal ischemia and reperfusion injury in the intermediate capillary plexus (ICP) and deep capillary plexus (DCP), i.e., the deep vascular complex. This leads to sublethal ischemic hypoxia in the middle retinal layers, predominantly affecting the inner nuclear layer (INL) [8]. Reports indicate that PAMM occurs predominantly in elderly patients, most of whom have underlying systemic vascular disorders, such as hypertension, hyperlipidemia, and diabetes mellitus [9], cases have also been reported in young, healthy females [10]. PAMM may occur in isolation [11] or concurrently with various retinal diseases, including retinal vein occlusion, cilioretinal artery occlusion, hypertensive retinopathy, and diabetic retinopathy [12]. Studies have also reported associations between PAMM and caffeine, vasopressor medications, oral contraceptives, migraines, severe hypovolemia, upper respiratory tract infections, and influenza vaccination [1, 11].

CAD is a common cause of ischemic stroke in young and middle-aged adults [13]. ICAD represents the most frequent subtype of CAD. DSA remains the gold standard for diagnosing ICAD [14]. The classic triad of ICAD consists of ipsilateral neck, head, and orbital pain; partial Horner’s syndrome; and cerebral or retinal ischemia [13]. The internal carotid arteries supply blood to both eyes, making ocular symptoms often the initial—and sometimes the only—manifestation of ICAD [15]. Recent studies have indicated that ICAD can lead to transient vision loss, CRAO/BRAO, ocular ischemic syndrome (OIS), ischemic optic neuropathy, sympathetic ophthalmoplegia, and ocular motor nerve palsies [16]. Muhi et al. [17] reported a case of “Paracentral acute middle maculopathy following carotid artery dissection”. The patient experienced transient vision decline along with systemic symptoms such as limb weakness, paresthesia, and dysarthria. After being diagnosed with ICAD, the patient developed sudden scotoma and was subsequently confirmed to have PAMM. In contrast, the present case is distinctive in that PAMM was the initial symptom in the absence of systemic manifestations, yet led to a definitive diagnosis of ICAD.

We searched multiple databases including PubMed, Embase, Web of Science, Scopus, the Cochrane Library, Wan fang, China National Knowledge Infrastructure (CNKI), and China Biology Medicine disc (CBM) from their inception until September 2025, with no language restrictions. Search terms included “paracentral acute middle maculopathy,” “PAMM,” “carotid artery dissection,” “internal carotid artery dissection,” “CAD,” and “ICAD.” A total of six relevant publications were identified (Table 1). Among these, three described PAMM following surgical intervention for ICAD; one reported PAMM resulting from traumatic ICAD; one presented ICAD with PAMM as the initial symptom, accompanied by systemic manifestations such as contralateral limb weakness and dizziness; and one documented PAMM occurring after a confirmed diagnosis of ICAD, along with systemic symptoms including limb weakness, paresthesia, and dysarthria. To date, no cases have been reported with PAMM as the initial symptom of ICAD in the absence of systemic manifestations.

Table 1 Retrieved Literature/Included studies

The mechanisms by which CAD causes ischemic stroke may result from hypoperfusion distal to the stenotic or occluded dissected vessel segment, or from artery-to-artery embolism due to thrombus formation within the dissection [23]. In the present case, ICAD manifested with PAMM as the initial symptom in the absence of systemic manifestations. The association between ICAD and PAMM likely stems from retinal microvascular compromise secondary to hemodynamic disturbances within the carotid system, it may result from hypoperfusion or embolism [24, 25]. Perfusion insufficiency or embolism occurring in the full thickness of the retina will lead to CRAO or BRAO. If it occurs only in the deep vascular complex, it will result in PAMM, because the deep vascular complex is the primary blood supply source for the retinal INL, and its ischemic injury has been confirmed as the core mechanism of PAMM [26]. Furthermore, microemboli dislodgement in patients with ICAD may exacerbate retinal ischemia, potentially establishing a dual pathological model of “hypoperfusion-embolism”. In this case, multiple thrombi were observed during the procedure, and ischemia caused by microthrombi embolizing the deep vascular complex cannot be ruled out.

Approximately 60% of carotid artery dissections (CAD) are spontaneous, while the remaining 40% are associated with identifiable triggers [27]. Reported precipitating factors include sneezing, vigorous coughing, neck massage, and physical activities such as weightlifting, badminton, golf, tennis, and yoga [28,29,30,31,32]. In the present case, detailed history taking after diagnosis revealed that the patient routinely engaged in vigorous neck rotation to alleviate cervical discomfort. Hyperextension, rotation, or forward flexion of the neck can lead to vascular stretching injury. This stretching may cause intimal damage, which can subsequently trigger arterial dissection (separation of the layers of the vessel wall) or intramural thrombus formation [33].

Based on this case, we recommend that young patients without underlying vascular diseases, clear history of trauma, identifiable triggers, or harmful habits, who present with sudden vision decline or paracentral scotoma and are diagnosed with PAMM upon ophthalmic examination, should be promptly referred to neurology for vascular imaging to rule out systemic causes of ocular pathology.

Conclusion

While ICAD is often associated with a history of trauma [23], the patient in this case reported a habit of vigorous neck rotation. It is noteworthy, however, that some cases lack documented evidence of antecedent mechanical injury, with potential triggers such as severe coughing or respiratory infections prior to onset [34–35]. Given its potential to cause ischemic neurological sequelae, clinicians must maintain a high index of suspicion to facilitate early identification and diagnosis. The association between ICAD and PAMM underscores the complex interplay between systemic vascular pathology and retinal microvascular compromise. In clinical practice, ophthalmologists should be vigilant for underlying carotid pathology in patients presenting with PAMM, while neurologists should actively monitor retinal perfusion status in those with ICAD: For patients with ICAD, neurologists should pay close attention to visual function. If visual abnormalities occur, prompt referral to an ophthalmology specialist for ocular assessment is recommended. Comprehensive fundus examinations, including fundus photography, NIR, and OCT/OCTA, should be performed to rule out related diseases caused by retinal perfusion abnormalities. Multidisciplinary collaboration and precision medicine strategies are pivotal for optimizing patient outcomes