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Learn more: PMC Disclaimer | PMC Copyright Notice Radiol Case Rep . 2026 Mar 27;21(6):2577–2582. doi: 10.1016/j.radcr.2026.02.043 Search in PMC Search in PubMed View in NLM Catalog Add to search Ruptured distal anterior cerebral artery (A2) aneurysm presenting with simultaneous bilateral intraparenchymal hemorrhage and acute subdural hematoma: A case report and literature review L Ruggeri L Ruggeri , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by L Ruggeri a , V Gulino V Gulino , MD b Neurosurgical Clinic AOUP “Paolo Giaccone”, Post Graduate Residency Program in Neurologic Surgery, Department of Biomedicine Neurosciences and Advanced Diagnostics, School of Medicine, University of Palermo, Viale Del Vespro 129, 90127 Palermo, Italy Find articles by V Gulino b, ⁎ , A Giovannini A Giovannini , MD b Neurosurgical Clinic AOUP “Paolo Giaccone”, Post Graduate Residency Program in Neurologic Surgery, Department of Biomedicine Neurosciences and Advanced Diagnostics, School of Medicine, University of Palermo, Viale Del Vespro 129, 90127 Palermo, Italy Find articles by A Giovannini b , R Lipani R Lipani , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by R Lipani a , G A Cinquemani G A Cinquemani , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by G A Cinquemani a , J Mandelli J Mandelli , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by J Mandelli a , S Marrone S Marrone , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by S Marrone a , G Manta G Manta , MD c Intensive Care Unit, Sant'Elia Hospital, via Luigi Russo 6, 93100, Caltanissetta, Italy Find articles by G Manta c , A Biancardino A Biancardino , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by A Biancardino a , B Campisi B Campisi , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by B Campisi a , A Borgognone A Borgognone , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by A Borgognone a , G Cipollina G Cipollina , MD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by G Cipollina a , D G Iacopino D G Iacopino , MD, PhD a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy Find articles by D G Iacopino a , L Basile L Basile , MD b Neurosurgical Clinic AOUP “Paolo Giaccone”, Post Graduate Residency Program in Neurologic Surgery, Department of Biomedicine Neurosciences and Advanced Diagnostics, School of Medicine, University of Palermo, Viale Del Vespro 129, 90127 Palermo, Italy Find articles by L Basile b Author information Article notes Copyright and License information a Unit of Neurosurgery, Sant’Elia Hospital, Via Luigi Russo 6, 93100 Caltanissetta, Italy b Neurosurgical Clinic AOUP “Paolo Giaccone”, Post Graduate Residency Program in Neurologic Surgery, Department of Biomedicine Neurosciences and Advanced Diagnostics, School of Medicine, University of Palermo, Viale Del Vespro 129, 90127 Palermo, Italy c Intensive Care Unit, Sant'Elia Hospital, via Luigi Russo 6, 93100, Caltanissetta, Italy ⁎ Corresponding author. [email protected] Received 2025 Oct 25; Revised 2026 Feb 12; Accepted 2026 Feb 18; Collection date 2026 Jun. © 2026 The Authors This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). PMC Copyright notice PMCID: PMC13059117 PMID: 41960133 Abstract Distal anterior cerebral artery (DACA) aneurysms are rare, representing a small fraction of intracranial vascular malformations. Their management is complex due to their deep interhemispheric location and often unfavorable morphology. We present an exceptionally rare case of a 56-year-old woman who suffered a rupture of a 5-mm A2-segment DACA aneurysm, leading to a unique combination of simultaneous bilateral frontal intraparenchymal hemorrhage and an acute subdural hematoma. This specific hemorrhagic pattern is significantly rarer than the typical subarachnoid hemorrhage and is often associated with high-pressure bleeding jets or arachnoid adhesions. The patient presented in a critical neurological state with rapidly progressing bilateral mydriasis. Following urgent decompressive craniectomy and microsurgical clipping, she achieved a favorable recovery. This case adds significant value to the literature by illustrating that DACA aneurysms should be considered in the differential diagnosis of nontraumatic bilateral frontal bleeding, and it demonstrates that even in the presence of severe multi-compartmental hemorrhage, prompt surgical intervention can lead to a positive long-term outcome. Keywords: Distal anterior cerebral artery aneurysm, Pericallosal aneurysm, Acute subdural hematoma, Bilateral intraparenchymal hemorrhage, Case report Introduction Distal anterior cerebral artery (DACA) aneurysms account for approximately 1.5%-9% of all intracranial aneurysms [ [1] , [2] , [3] , [4] ]. Most arise from the A3 segment (pericallosal-callosomarginal junction), while A2 segment aneurysms are rarer, representing only 5%-22% of DACA cases [ 1 ] ( Table 1 ). Their deep location within the interhemispheric fissure makes surgical exposure and aneurysm neck control technically demanding [ 4 ]. Table 1. Distribution of DACA aneurysms by segment. DACA segment Percentage of all DACA aneurysms Percentage of all intracranial aneurysms Notes Reference A2 5-22 0.2-1 Proximal pericallosal aneurysms [ 1 , 2 ] A3 88 2-7 Most frequent, especially anterior [ 2 ] A4-A5 5-20 0.3-0.6 Distal, rarer [ 2 ] Open in a new tab This table summarizes the frequency of distal anterior cerebral artery (DACA) aneurysms by segment (A2-A5) and their proportion among all intracranial aneurysms. As shown, A2 aneurysms are rare (5%-22%) , highlighting the technical and diagnostic challenges associated with these proximal pericallosal lesions . Although subarachnoid hemorrhage (SAH) is the most common presentation, atypical patterns, such as acute subdural hematoma (aSDH) or intraparenchymal hemorrhage (IPH), may also occur [ [2] , [3] , [4] ]. The simultaneous occurrence of bilateral IPH and aSDH following rupture of a single DACA aneurysm, however, represents an extraordinary clinical event. This report details the management of such a presentation, discussing the surgical challenges and the underlying pathophysiological mechanisms involved. Case presentation A 56-year-old woman with a history of hypertension and active smoking was admitted following a sudden loss of consciousness preceded by a severe headache. On initial examination, her GCS was 6/15 (E1 V1 M4). Her neurological status deteriorated rapidly: she initially presented with a dilated right pupil, which quickly progressed to bilateral reactive mydriasis, indicating critical transtentorial herniation. Emergency non-contrast computed tomography (CT) revealed a complex hemorrhagic pattern: bilateral frontal IPH, diffuse SAH (Fisher grade IV), and a right fronto-temporo-parietal aSDH ( Fig. 1 ). CT angiography (CTA) identified a 5-mm saccular aneurysm on the A2 segment of the right pericallosal artery ( Fig. 2 ). Fig. 1. Open in a new tab Basal computed tomography (CT) scans of the brain. Image (A): Non-contrast axial CT showing bilateral frontal intraparenchymal hemorrhage (IPH). Red arrows indicate the location and extent of the hemorrhages in both frontal lobes. Image (B): Non-contrast axial CT demonstrating right fronto-temporo-parietal acute subdural hematoma (aSDH) alongside left frontal IPH, highlighted with yellow arrows. These images highlight the complex multi-compartmental hemorrhage, emphasizing the rarity of bilateral IPH with aSDH in aneurysmal rupture. Fig. 2. Open in a new tab Angio-computed tomography (CT) 3D reconstruction of the pericallosal artery aneurysm (A2 segment). Image (A) (anteroposterior view) and Image (B) (lateral view): 3D reconstructions clearly show the size, morphology, and precise location of the 5-mm A2 aneurysm. The aneurysm dome is indicated with red circles, illustrating the source of the hemorrhage. These reconstructions complement the basal CT by confirming the vascular origin of the bleeding. The clinical timeline was as follows: presentation occurred within 1 hour of ictus, immediate imaging, and transfer to the operating room for emergency surgery within 2 hours. A right frontotemporoparietal decompressive craniectomy was performed. After the evacuation of the aSDH, the interhemispheric fissure was accessed, and the aneurysm was clipped using a 60° curved Sugita clip. Finally, both frontal IPHs were evacuated. Postoperative CT confirmed aneurysm exclusion and successful decompression ( Figs. 3 and 4 ). Following rehabilitation and subsequent cranioplasty, the patient showed significant improvement. At 18 months, she was conscious and ambulatory with only mild right-sided hemiparesis. Follow-up MRI (T1-weighted) at 18 months confirmed the stability of the result ( Fig. 5 ). Fig. 3. Open in a new tab Postoperative computed tomography (CT) scan (axial view): Non-contrast CT demonstrating successful aneurysm clipping and evacuation of bilateral frontal IPHs and right aSDH. Arrows indicate areas of previous hemorrhage now decompressed. The image confirms aneurysm exclusion and mass effect relief, critical for assessing immediate surgical success. Fig. 4. Open in a new tab Post-cranioplasty computed tomography (CT) scan (6 weeks post-op): Axial CT showing restoration of cranial integrity after right frontotemporo-parietal decompressive craniectomy. The bone flap is properly positioned, and prior hematomas have resolved. This image highlights postsurgical recovery and anatomical normalization. Fig. 5. Open in a new tab Long-term follow-up MRI (T1-weighted, 18 months post-op): Axial T1-weighted MRI showing resolution of previous hemorrhagic lesions in both frontal lobes. No new abnormalities are noted. The image demonstrates favorable neurological recovery and long-term stability of the surgical outcome, reinforcing the effectiveness of early microsurgical intervention. Discussion DACA aneurysm rupture most commonly produces SAH, with or without associated unilateral intraparenchymal extension [ [5] , [6] , [7] ]. The simultaneous occurrence of bilateral IPH and aSDH from a DACA rupture is a clinical rarity that challenges standard diagnostic paradigms [ [8] , [9] ]. In our case, the bilateral distribution of the IPH and the associated aSDH initially suggested a traumatic etiology. However, the CTA proved the aneurysmal origin. Bilateral IPH after the rupture of a single DACA aneurysm has been reported in fewer than five in the literature, highlighting the exceptional nature of this presentation ( Table 2 ). Table 2. Reported cases of distal anterior cerebral artery (DACA) aneurysms with aSDH and/or intraparenchymal hemorrhage. Study Age/Sex DACA segment Clinical presentation Hemorrhage type Treatment Outcome Barton et al. [ 2 ] 54/F A3 Sudden headache aSDH Microsurgical clipping Good Watanabe et al. [ 4 ] 62/M A2 Coma aSDH + ICH Microsurgical clipping Partial recovery Watanabe et al. [ 4 ] — A2 Headache, neurological deficit aSDH + ICH Microsurgical clipping Good Singh et al. [ 10 ] 48/F A2 Headache + motor deficit Bilateral ICH Microsurgical clipping Good Ahmad et al. [ 11 ] 50/M A3 Sudden headache aSDH Endovascular Good Petrov et al. [ 12 ] 57/F A2 Coma aSDH Endovascular Good Raut et al. [ 13 ] 60/M A3 Headache aSDH Microsurgical clipping Good Gao et al. [ 14 ] 45/F A2 Headache + confusion aSDH Microsurgical clipping Good Meguins et al. [ 15 ] — Bilateral A2 Headache Bilateral ICH Microsurgical clipping Good Hubbard et al. [ 16 ] — A2 Coma aSDH Microsurgical clipping Good Current case 56/F A2 Coma, dilated pupils Bilateral ICH + aSDH Microsurgical clipping + decompression Partial recovery Open in a new tab This table provides a literature overview of previously reported DACA aneurysms presenting with acute subdural hematoma (aSDH) and/or intraparenchymal hemorrhage (IPH) , including patient age, aneurysm segment, hemorrhage type, treatment modality, and outcome. It emphasizes the rarity of bilateral IPH and multi-compartmental hemorrhage , placing the current case in context. Pathophysiology of the hemorrhage Several mechanisms may explain this rare presentation. IPH occurs because DACA aneurysms are frequently embedded within the brain parenchyma along the narrow interhemispheric fissure. The occurrence of bilateral IPH, however, is exceedingly rare. This rarity is primarily explained by the anatomical course of the DACA, which typically supplies medial frontal territories in a unilateral or asymmetrically dominant fashion. Consequently, rupture of a single aneurysm more often directs hemorrhagic dissection toward one frontal lobe. Several mechanisms have been proposed to explain bilateral parenchymal involvement. First, aneurysms arising at or near the pericallosal–callosomarginal junction may project centrally within the interhemispheric fissure, allowing the rupture jet to propagate symmetrically into both frontal lobes. Second, confined cisternal spaces may channel high-pressure bleeding across the midline, particularly when the aneurysm dome is embedded within the parenchyma. Finally, adhesions resulting from prior minor “sentinel” hemorrhages may tether the aneurysm dome to adjacent brain surfaces, facilitating multidirectional rupture and contributing to bilateral hematoma formation. These mechanisms, individually or in combination, may account for the exceptionally uncommon presentation observed in our case. The aSDH component likely arises from a high-pressure jet of blood that tears through the arachnoid membrane into the subdural space or from adhesions between the aneurysm sac and the arachnoid layer caused by previous minor “sentinel” bleeds [ [10] , [11] , [12] , [17] ]. Radiological differential diagnosis When faced with bilateral frontal IPH and aSDH, clinicians must consider the following: • Traumatic brain injury: Usually associated with skull fractures or scalp swelling but often lacks diffuse SAH in the pericallosal cistern. • Cerebral venous sinus thrombosis (CVST): Can cause bilateral frontal hemorrhages due to venous infarction, but the bleeding is typically more cortical and edema-heavy. • Hemorrhagic transformation of bifrontal infarcts: generally follows a clear vascular territory and lacks the acute surgical mass effect of an aneurysm rupture. The presence of blood in the pericallosal cistern on CT should always trigger a CTA to rule out a DACA aneurysm. As shown in Table 1 , A2 aneurysms are less frequent than A3, and Table 2 summarizes reported cases of DACA aneurysms presenting with aSDH and/or IPH, emphasizing the rarity of bilateral involvement. Surgical management The deep interhemispheric approach remains the gold standard, despite the technical challenges posed by the narrow surgical corridor and the risk of intraoperative rupture (0%-15%) [ 18 ]. In our patient, the need for both hematoma evacuation and aneurysm clipping made microsurgery superior to endovascular coiling. Table 3 summarizes how microsurgery often provides better outcomes in cases requiring mass effect relief. Table 3. Comparison of microsurgical clipping versus endovascular treatment for distal anterior cerebral artery (DACA) aneurysms. Treatment Number of cases Complete recovery (%) Partial recovery (%) Mortality (%) Reference Microsurgical clipping 501 70-80 15-20 0-5 [ 17 , 18 ] Endovascular coiling 85 65-75 15-25 0-10 [ [19] , [20] , [21] ] Open in a new tab This table compares clinical outcomes between microsurgical clipping and endovascular coiling in the treatment of DACA aneurysms. Complete and partial recovery rates, as well as mortality, are listed, demonstrating that microsurgery often provides superior outcomes when mass effect relief is needed, as in cases like the present one. Conclusion This case illustrates an exceptionally rare presentation of a DACA aneurysm rupture, with the unique combination of simultaneous bilateral IPH and aSDH. Such a hemorrhagic pattern is extremely uncommon, and its recognition is critical, as it can easily mimic trauma or venous pathology. Our experience highlights that early radiological identification using CT and CTA, followed by prompt microsurgical intervention—including decompression, hematoma evacuation, and aneurysm clipping—can result in favorable neurological outcomes, even in patients presenting with severe multi-compartmental hemorrhage and bilateral mydriasis. This report reinforces the importance of including DACA aneurysms in the differential diagnosis of nontraumatic bilateral frontal bleeding and provides valuable insights into the surgical management of these challenging cases, contributing practical knowledge to the neurosurgical and radiological literature. Data availability Data sharing is not applicable to this article, as no new data were created or analyzed in this study. Funding The author(s) received no financial support for the research, authorship, and/or publication of this article. Patient consent Written informed consent was obtained from the patient(s) for their anonymized information to be published in this article. Footnotes Competing Interests: The authors have declared that no competing interests exist. References 1. Aboukaïs R., Zairi F., Bourgeois P., Boustia F., Leclerc X., Lejeune J.P. Pericallosal aneurysm: a difficult challenge for microsurgery and endovascular treatment. 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