Mechanical Thrombectomy as First-line Endovascular Therapy for Acute Middle Cerebral Artery Occlusion Due to Arterial Dissection: A Case Report and Literature Review

Abstract

Isolated middle cerebral artery dissection is a rare cause of acute ischemic stroke, accounting for approximately 2.4% of anterior circulation events. Due to its rarity, no optimal management strategy has been established, and evidence regarding the safety and efficacy of endovascular therapy remains limited. We report a 26-year-old male who presented with sudden-onset headache, vomiting, right hemiparesis, and aphasia. Magnetic resonance imaging revealed multiple faint diffusion-restricted lesions in the left hemisphere (DWI-ASPECTS 7), and magnetic resonance angiography demonstrated occlusion of the left middle cerebral artery (M2 segment). Emergency mechanical thrombectomy using a combined stent retriever and aspiration technique achieved complete recanalization (Thrombolysis in Cerebral Infarction 3), although significant residual stenosis persisted. Balloon angioplasty restored satisfactory luminal patency without stent placement. Postoperative contrast-enhanced vessel wall imaging showed mural thickening and marked enhancement of the left M2 segment, confirming arterial dissection. The patient recovered well, and no infarct progression or re-occlusion occurred during the 6-month follow-up. The present case suggests that endovascular therapy employing mechanical thrombectomy as the first-line strategy may be one of the therapeutic options for acute middle cerebral artery occlusion secondary to arterial dissection. The procedural strategy and device selection should be individualized to minimize vessel injury. Furthermore, given the potential for dynamic vascular changes, long-term radiological surveillance remains essential.

Introduction

Isolated middle cerebral artery (MCA) dissection accounts for approximately 2.4% of acute ischemic strokes in the intracranial anterior circulation; vertebrobasilar artery dissection is seen more often.^1,2)

Recent advances in thrombectomy devices have markedly improved recanalization rates in patients with acute intracranial large-vessel occlusion. Endovascular treatment, including mechanical thrombectomy, is now the standard of care for such patients.³⁾ However, because of the rarity of intracranial large-vessel occlusion due to dissection, no randomized controlled trials have been conducted. Consequently, objective data regarding therapeutic outcomes remain scarce, and standardized treatment protocols have not been established.

According to the guidelines for treating intra- and extracranial arterial dissection published by the European Stroke Organization in 2021, mechanical thrombectomy is recommended for large-vessel occlusion, including those caused by arterial dissection,⁴⁾ although among the studies reviewed in the preparation of these guidelines, only one case involved MCA dissection. The majority of evidence supporting the European Stroke Organization guidelines is derived from single-center retrospective studies, yielding a very low level of evidence. Nevertheless, in a subset of patients with progressive symptoms despite optimal medical therapy, rescue endovascular intervention may confer clinical benefit and should be judiciously considered on an individualized basis.

To determine whether endovascular treatment is a safe and effective therapeutic strategy for addressing the rare entity of MCA occlusion secondary to dissection, further clinical data are needed.

We present a patient with acute MCA occlusion attributable to arterial dissection, diagnosed based on clinical and neuroradiological findings, and treated with mechanical thrombectomy. We further reviewed the literature on patients with isolated MCA dissection who underwent acute-phase thrombectomy and summarized the therapeutic strategies, procedural outcomes, and clinical prognoses.

Case Report

A 26-year-old male with no significant medical history presented with sudden-onset headache and vomiting, followed by right-sided hemiparesis and aphasia. On admission, the patient was alert and oriented but exhibited motor weakness of the right upper and lower extremities (Manual Muscle Testing 3/5), sensory disturbance (5/10), and motor aphasia. The National Institutes of Health Stroke Scale (NIHSS) score was 6.

Diffusion-weighted images obtained on emergency magnetic resonance imaging (MRI) demonstrated multiple faint high-intensity areas in the left frontal, temporal, parietal, and insular cortices (DWI-ASPECTS 7) (Figure 1A). MR angiography (MRA) demonstrated occlusion of the left MCA (M2 segment) (Figure 1B). Emergency mechanical thrombectomy was performed because the patient had functionally disabling deficits with progressive neurological deterioration, despite a relatively low NIHSS score of 6.

Figure 1

Brain MRI demonstrating multiple faint hyperintense lesions on diffusion-weighted images in the left frontal, temporal, parietal, and insular cortices (DWI-ASPECTS 7) (A). MR angiography showing occlusion of the left middle cerebral artery (M2 segment) (B, arrow).

MR: magnetic resonance; MRI: magnetic resonance imaging

Endovascular revascularization was performed. A balloon guiding catheter (8 Fr Optimo; Tokai Medical Products, Aichi, Japan) was placed in the left internal carotid artery, and angiography confirmed occlusion of the left MCA (M2) (Figure 2A). An aspiration catheter (AXS Vecta 71; Stryker Neurovascular, Fremont, CA, USA) served as the outer catheter, while a TrevoTrak 21 microcatheter (Stryker, Kalamazoo, MI, USA) was navigated to the proximal occlusion site. Contrast injection through the microcatheter revealed a contrast void consistent with a thrombus (Figure 2B). Although arterial dissection was suspected based on the clinical presentation, percutaneous transarterial angioplasty (PTA) alone or PTA with stenting was considered as an alternative treatment from a safety standpoint. However, because microcatheter angiography confirmed the presence of thrombus, thrombus retrieval was prioritized, and a combined stent retriever and aspiration technique was selected.

Figure 2

Left internal carotid angiogram revealing occlusion of the left middle cerebral artery (M2 segment) (A, arrow). Contrast injection through a microcatheter positioned proximal to the occlusion demonstrated a contrast defect corresponding to a thrombus (B, arrow). Complete reperfusion (TICI 3) was achieved following thrombectomy, although severe residual stenosis was observed in the M2 segment (C, arrow). Balloon dilation of the stenotic segment was performed using a balloon microcatheter (D, arrow), resulting in satisfactory luminal expansion (E, arrow).

TICI: Thrombolysis in Cerebral Infarction

A stent retriever (Trevo NXT 4 × 41 mm; Stryker) was deployed across the occlusion, and both the stent retriever and thrombus were removed with the aspiration catheter. The extracted thrombus was macroscopically red; histopathology revealed that it was comprised of an erythrocyte-rich red thrombus and a platelet/fibrin/neutrophil-rich white thrombus. Complete reperfusion (Thrombolysis in Cerebral Infarction [TICI] 3) was achieved, although marked residual stenosis was observed in the M2 segment (Figure 2C). Given the severe residual stenosis with delayed distal flow, we considered the risk of re-occlusion to be high and proceeded with PTA.

Dual antiplatelet therapy (aspirin 200 mg and prasugrel 10 mg) was administered, and balloon angioplasty was performed using a balloon microcatheter (UNRYU 2.0 × 10 mm; Kaneka Medix, Osaka, Japan) (Figure 2D). Satisfactory luminal expansion was achieved with mild residual stenosis (approximately 20%), and no interval change was observed after a 30-minute observation period; therefore, the procedure was completed (Figure 2E). Postoperatively, the patient's neurological symptoms improved. MRI on the first postoperative day showed no infarct progression, and MRA confirmed sustained patency of the left MCA. Dual antiplatelet therapy (aspirin 100 mg/day and prasugrel 3.75 mg/day) was continued for 3 weeks; thereafter, aspirin monotherapy (100 mg/day) was administered.

On postoperative day 5, vessel wall imaging with contrast-enhanced MRI was performed. Vessel wall images were acquired using a Philips Ingenia 3T system; the scanning conditions were repetition time 400 ms, echo time 13 ms, flip angle 75°, number of excitations 1, field of view 230 × 220 mm, matrix 288 × 288, slice thickness 0.9 mm, and echo train length 20. Contrast-enhanced T1-weighted imaging demonstrated mural thickening and contrast enhancement of the left M2 segment of the MCA (Figure 3A). Based on the vessel wall imaging with contrast-enhanced MRI, arterial dissection was diagnosed.

Figure 3

Postoperative findings.

Day 5: Contrast-enhanced MRI with vessel wall imaging (A-1: non-contrast T1; A-2: contrast-enhanced T1; A-3: magnified view of the highlighted region demonstrating eccentric circumferential wall thickening and contrast enhancement of the left M2 segment of the middle cerebral artery.)

Day 70: The patient was re-admitted due to headache and vomiting. Cerebral angiography (B, arrow at the left MCA M2 segment) showed severe stenosis (68%, Warfarin-Aspirin Symptomatic Intracranial Disease criteria). Note post-stenotic arterial dilation (B, arrowhead). On non-contrast T1-weighted thin-slice MRI, the vessel wall at the stenotic segment exhibited eccentric moderate wall thickening with iso- to high-intensity signal (C-1, arrow), while the dilated segment demonstrated circumferential mild wall thickening with diffusely iso- to high-intensity signal (C-2, arrow). CT perfusion demonstrated no reduction in the cerebral blood flow in the left MCA territory (D).

MCA: middle cerebral artery; MRI: magnetic resonance imaging

Twenty days after symptom onset, the right-sided motor weakness and sensory disturbance of the upper and lower extremities, and motor aphasia present at admission had completely resolved, and the patient was discharged home with a modified Rankin Scale score of 0. However, on postoperative day 70, the patient was re-admitted with recurrent headache and vomiting. There were no new neurological deficits. MRI showed recurrent stenosis of the left MCA M2 segment. Cerebral angiography demonstrated severe stenosis (68% by Warfarin-Aspirin Symptomatic Intracranial Disease criteria) with post-stenotic arterial dilation (Figure 3B). On non-contrast T1-weighted thin-slice MRI, the vessel wall at the stenotic segment exhibited eccentric moderate wall thickening with iso- to high-intensity signal, while the dilated segment demonstrated circumferential mild wall thickening with diffusely iso- to high-intensity signal (Figure 3C). Computed tomography (CT) perfusion (Siemens Somatom Definition AS 64-slice CT scanner; syngo. via VB60) revealed no reduction in the cerebral blood flow (Figure 3D). As there was no neurological deterioration or perfusion deficit, revascularization was deferred, and the patient was managed conservatively. The post-stenotic dilatation may reflect distal extension of the dissection with the formation of a dissecting aneurysm. Careful follow-up with frequent outpatient MRI examinations is planned in view of the potential risk of progressive dilatation and rupture.

Consent for publication was obtained from the patient.

Discussion

In the present study, we investigated the efficacy and safety of employing mechanical thrombectomy as the first-line endovascular treatment for MCA occlusion secondary to isolated MCA dissection by reviewing 19 patients, including our own case, who underwent this procedure. Where available, the patient age, gender, the methods and outcomes of acute-phase endovascular treatment, procedure-related complications, subsequent chronic-phase interventions, and long-term outcomes were recorded (Table 1).^1,5-9)

Table 1

Review of Previously Reported Patients with Middle Cerebral Artery Dissection Treated by Mechanical Thrombectomy

Article (#)	Number of cases	y.o.	Sex	Occlusion site	NIHSS at admission	Initial EVT in the acute phase	Additional EVT in the acute phase	Recanalization (TICI)	Complication	EVT in the chronic phase	mRS at discharge	Long-term mRS (months)
EVT: endovascular therapy; F: female; M: male; mRS: modified Rankin Scale; N/A: not reported; NIHSS: National Institutes of Health Stroke Scale; PTA: percutaneous transarterial angioplasty; TICI: Thrombolysis in Cerebral Infarction; t-PA: tissue plasminogen activator
Yoon et al. (5), 2019	1	27	M	M1	NIHSS 6	Stent thrombectomy	Stent placement	○ (III)	None	None	N/A	0(3 months)
Adeeb et al. (6), 2020	1	11	F	M1	N/A	Stent thrombectomy	Intra-arterial injection of t-PA	○ (IIb)	None	None	2	1(14 months)
Park et al. (1), 2020	7	46.5 (average)	F (n=1) M (n=1) N/A(n=5)	M1 (n=7)	NIHSS 11.1 (average)	aspiration thrombectomy (n=7)	None (n=7)	○(N/A) (n=6) × (n=1)	SAH due to vessel perforation (n=1) None (n=6)	Stent placement (n=1) None (n=6)	6 (n=1) N/A (n=6)	0 (n=2) (3 months) 1 (n=1) (3 months) 2 (n=2)(3 months) 6 (at discharge)
Wattanasen et al. (7), 2024	1	62	F	M1	NIHSS 14	Stent thrombectomy	PTA	○(N/A)	None	Stent placement	N/A	N/A
Lin et al.(8), 2024	1	34	M	M2	NIHSS 9	Combined technique	None	○(N/A)	None	None	N/A	N/A
Pedowski et al. (9), 2024	7	N/A(n=7)	N/A(n=7)	N/A (n=7)	N/A (n=7)	Mechanical thrombectomy (n=7)	None (n=7)	○ (III) (n=7)	N/A (n=7)	Stent placement (n=7)	N/A (n=7)	N/A(n=7)
Our case	1	26	M	M2	NIHSS 6	Combined technique	PTA	○ (III)	None	None	0	0(3 months)

The mean age of 7 patients was 35.7 years (median 34 years); there was no gender prevalence in the study population. The occlusion site in 10 of 12 patients (83%) was at the M1 segment; in 2, it was at the M2 segment. The mean NIHSS at presentation was 10.3, reflecting moderate neurological deficits at onset. Patients typically present with sudden, severe headache accompanied by focal neurological deficits such as hemiparesis, aphasia, or visual disturbances.

As our young 26-year-old patient presented with the typical clinical symptoms of arterial dissection, i.e., abrupt headache followed by right-sided hemiparesis and aphasia, we suspected MCA occlusion secondary to dissection. However, because emergency mechanical thrombectomy was promptly performed, a definitive preoperative diagnosis of dissection could not be established radiologically. Lin et al.⁸⁾ reported the utility of MRI-based vessel-wall imaging for diagnosing arterial dissections. However, due to the time required, it is often impractical in acute settings. Also, even in dissection-related occlusions, the diagnostic sensitivity of imaging modalities remains low, with some reports indicating rates below 10%.¹⁰⁾ In the series reported by Park et al.,¹⁾ an intimal flap was identified proximal to the occlusion site during acute-phase cerebral angiography; this allowed for a diagnosis of dissection prior to thrombectomy. Aspiration thrombectomy without microcatheter passage through the occluded segment was performed, thereby minimizing the risk of pseudoaneurysm rupture, a serious complication associated with microcatheter advancement. As we did not encounter the typical intimal flap near the occlusion site, it was difficult to make a pre-thrombectomy diagnosis of dissection.

Consequently, clinical suspicion of dissection can be based on patient age, the symptom pattern, and past medical history. Etiologically, arterial dissection has been associated with factors such as head trauma, connective tissue disorders, inflammation, and atherosclerosis.^11,12) In our patient, neither family nor medical history suggested predisposing factors. Blood test results for autoimmune antibodies, protein C and S levels, and homocysteine concentrations were within normal limits, providing no evidence of an underlying systemic disease.

The European Stroke Organization has published evidence-based guidelines on the management of both extracranial and intracranial arterial dissections.⁴⁾ These guidelines recommend endovascular therapy for symptomatic large-vessel occlusion secondary to dissection; however, the majority of cited studies pertain to internal carotid or vertebral artery dissections. In approximately 90% of patients with internal carotid artery dissection, mechanical thrombectomy achieved reperfusion (TICI 2b-3).^13,14) Our review found that reperfusion was obtained in all of the previously reported cases with MCA dissection-related occlusion. This suggests that mechanical thrombectomy is an effective therapeutic strategy not only for carotid artery but also for MCA dissections.

According to Puggaard et al.,¹³⁾ the incidence of severe complications associated with thrombectomy for dissection-related and unrelated carotid occlusions was similar. A technical complication was reported in only one of 18 previously reported patients with MCA dissection, suggesting that procedural thrombectomy risks are not higher in patients with MCA than carotid dissection.

Strategies employed for mechanical thrombectomy include aspiration catheter only, stent-retriever-only, and methods that combine the use of both devices. The optimal and safest modality to address occlusive lesions secondary to arterial dissection remains to be identified. Based on our literature review, the initial thrombectomy technique used an aspiration catheter alone (n = 7), a stent retriever alone (n = 3), and a combined technique in 2 of 12 patients; it was not indicated in 7 patients. The 7 aspiration-only cases and the 7 cases where the technique was not reported were treated at the same institution. Stent retrievers alone or a technique combined with aspiration catheters was applied in the other 5 patients. Stent retrievers tended to be preferred, although institutional practice patterns may have dictated the thrombectomy strategy. Centers favoring aspiration-only techniques reported instances of vessel perforation when attempting to navigate a microcatheter across a dissected segment. Rather than crossing the occlusion, the thrombus was retrieved by advancing an aspiration catheter to the proximal edge of the lesion.¹⁾ We adopted a combined stent-retriever and aspiration approach to minimize direct mechanical traction exerted on the fragile vessel wall. When advancing the microcatheter across the occlusion, meticulous attention was paid to the micro-guidewire tip to ensure its smooth progression before advancing the microcatheter. However, as any attempt at thrombectomy in a dissected artery exerts mechanical stress on the vessel, whether by microcatheter traversal, stent-retriever deployment, or aspiration-catheter manipulation, exceptional caution is indicated to mitigate the risk of procedural complications.

Stent deployment for MCA dissection is considered a highly effective therapeutic option as it mechanically dilates the stenotic segment and provides intraluminal support that compresses the vessel wall, thereby preventing further propagation of the dissection. However, the appropriateness of stent placement during the acute phase remains a matter of debate. In the hyperacute setting, the antiplatelet effect is often insufficient, posing a significant risk of in-stent thrombosis and subsequent re-occlusion. The application of dual antiplatelet therapy may increase the likelihood of hemorrhagic complications. Because we obtained adequate luminal expansion and restoration of the blood flow by PTA alone, we deemed stent placement during the acute phase unnecessary. Our literature review revealed that, during the initial endovascular procedure, 2 patients underwent PTA, 1 underwent stent deployment, and the other 16 were treated by thrombectomy alone in the acute phase. However, in a subset of patients, rescue stent deployment may be beneficial, and decisions regarding acute-phase stenting should be made on an individualized basis by carefully weighing the anticipated therapeutic benefit against the procedural and pharmacological risks. In particular, acute stent placement may be appropriate when the dissected segment exhibits severe stenosis with a high risk of re-occlusion or when the intimal flap exhibits marked mobility.

On the other hand, a stent was typically placed during the chronic phase after a defined period of dual antiplatelet therapy. From our review of the literature, in 10 of the 19 patients, stents were placed in the chronic phase. Post-stenting, dual antiplatelet therapy was delivered for a limited period followed by transition to monotherapy. Others^8,15,16) reported that MCA dissections exhibited dynamic morphological changes on follow-up images. This underscores the necessity of regular radiological surveillance. We observed persistent stenotic and dilational changes in the dissected segment more than 2 months after the procedure. Although we encountered no ischemic symptoms or perfusion deficits during a 6-month follow-up period, our patient was managed conservatively with ongoing observation. As progressive dilation may culminate in aneurysm formation requiring intervention,¹⁶⁾ vigilant longitudinal follow-up remains essential.

Conclusion

We reported a patient with acute MCA occlusion secondary to isolated MCA dissection who underwent emergency mechanical thrombectomy as the first-line endovascular treatment. We also present a review of previously published cases with a focus on the therapeutic strategies, procedural outcomes, and prognoses. Our findings suggest that mechanical thrombectomy is a relatively effective treatment option for MCA occlusion due to arterial dissection. As severe procedural complications have been reported, to avoid such complications, the possibility of arterial dissection should be thoroughly considered prior to treatment, and the careful selection of the appropriate thrombectomy technique and devices is essential to minimize procedural risks; depending on the individual case, alternative strategies such as PTA alone or PTA combined with stent placement should also be considered. As MCA dissection may elicit dynamic morphological changes over time, regular radiological follow-up and vigilant long-term observation are required.

Disclaimer

Author Yasushi Takagi is one of the Editorial Board members of the Journal. This author was not involved in the peer-review or decision-making process for this paper.

Conflicts of Interest Disclosure

All authors have no conflict of interest.

Funding

The authors have no funding sources to disclose.

Patient Consent

Informed consent was obtained from the patient for the publication of this case report and the accompanying images.

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