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---
title: "Fusiform Arterial Enlargement"
docid: "31d50b93-b057-4da3-86b5-4cc8fb0bc806"
authors:
- key: "2bca6b86-1eca-4e93-b997-4e18913686a7"
value: "Hediyeh Baradaran, MD, MS"
- key: "f184750a-90b4-47a7-907b-23b05d70357a"
value: "Chang Yueh Ho, MD"
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name: "Brain"
slug: "brain"
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name: "Differential Diagnosis"
slug: "differential-diagnosis"
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name: "Arteries"
slug: "arteries"
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slug: "anatomically-based-differentials"
treeNodeId: "9955b05e-9840-401a-b3da-4039f8b22a35"
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name: "Fusiform Arterial Enlargement"
slug: "fusiform-arterial-enlargement"
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lastUpdated: "02/22/23"
pageDescription: "Fusiform Arterial Enlargement"
pageKeywords: "Brain, Differential Diagnosis, Arteries, Anatomically Based Differentials, Fusiform Arterial Enlargement"
pageTitle: "Fusiform Arterial Enlargement | STATdx"
enhancedTitle: "Fusiform Arterial Enlargement"
type: "DDX"
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breadcrumbs:
- "Brain"
- "Differential Diagnosis"
- "Arteries"
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---
# ESSENTIAL INFORMATION
- ## Key Differential Diagnosis Issues
- Ectasia = elongated/tortuous artery
- Fusiform aneurysm
- Long-segment fusiform arterial dilatation
- Can be acute (dissecting) or chronic (atherosclerosis, nonatherosclerotic vasculopathy)
- ## Helpful Clues for Common Diagnoses
- **Dolichoectasia**
- Dilated/elongated arteries ± slow flow
- Vessel layers intact
- Older patients, chronic hypertension
- Vertebrobasilar > internal carotid artery (ICA)
- Ectasia often extends into branches
- **Atherosclerotic Fusiform Aneurysm**
- Thick wall ± organized thrombus
- Variable slow flow
- **Dissecting Aneurysm/Pseudoaneurysm**
- Focal arterial dilatation
- Trauma = most common etiology
- Next to hard/fixed structures (bone, dura)
- **Nonaneurysmal Dissection**
- Vertebral > basilar > ICA
- Lacks changes of atherosclerosis in other vessels
- Can be spontaneous or traumatic
- ## Helpful Clues for Less Common Diagnoses
- **CNS Vasculitis**
- Involves multiple vessels
- Alternating stenoses and fusiform dilatations
- **Inherited Connective Tissue Disorders**
- Abnormal connective tissue involves vessel walls
- Aneurysm and dissections
- Thoracic aorta most common location
- **HIV Infection**
- Vasculopathy may be present in children or adults
- Multifocal fusiform enlargement involving supraclinoid ICA and basilar artery
- No consistent infectious agent isolated
- ## Helpful Clues for Rare Diagnoses
- **Giant Serpentine Aneurysm**
- Large, partially thrombosed mass
- Distal branches arise from aneurysm dome
- Lacks definable neck
- ICA/middle cerebral artery > vertebrobasilar artery
- **Atypical Saccular Aneurysm**
- Arises from vessel bifurcations
- Long "aspect ratio" → fusiform appearance
- Often multilobulated, bizarre
## References
# Selected References
1. [Kyle K et al: Contrasting cases of HIV vasculopathy associated fusiform aneurysms. Neurohospitalist. 13(1):69-73, 2023](http://www.ncbi.nlm.nih.gov/pubmed/?term=36531848%5Bpmid%5D)
1. [Chung CY et al: Imaging intracranial aneurysms in the endovascular era: surveillance and posttreatment follow-up. Radiographics. 42(3):789-805, 2022](http://www.ncbi.nlm.nih.gov/pubmed/?term=35333634%5Bpmid%5D)
1. [Ritchey Z et al: Stroke recurrence in children with vertebral artery dissecting aneurysm. AJNR Am J Neuroradiol. 43(6):913-8, 2022](http://www.ncbi.nlm.nih.gov/pubmed/?term=35550284%5Bpmid%5D)
1. [Wang MX et al: Neurofibromatosis from head to toe: what the radiologist needs to know. Radiographics. 42(4):1123-44, 2022](http://www.ncbi.nlm.nih.gov/pubmed/?term=35749292%5Bpmid%5D)
1. [Law-Ye B et al: Considerations on the relevance of cerebral fusiform aneurysms observed during HIV infection. Clin Neuroradiol. 28(3):357-65, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=28378026%5Bpmid%5D)
1. [Kim ST et al: Prevalence of intracranial aneurysms in patients with connective tissue diseases: a retrospective study. AJNR Am J Neuroradiol. 37(8):1422-6, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=26992822%5Bpmid%5D)
1. [van Oel LI et al: Reconstructive endovascular treatment of fusiform and dissecting basilar trunk aneurysms with flow diverters, stents, and coils. AJNR Am J Neuroradiol. 34(3):589-95, 2013](http://www.ncbi.nlm.nih.gov/pubmed/?term=22918431%5Bpmid%5D)
1. [Park SH et al: Intracranial fusiform aneurysms: it's pathogenesis, clinical characteristics and managements. J Korean Neurosurg Soc. 44(3):116-23, 2008](http://www.ncbi.nlm.nih.gov/pubmed/?term=19096660%5Bpmid%5D)
## Images
### Selected Images
![Axial CT shows fusiform dilatation and tortuosity of the basilar artery <img src='img/arrows/CS.png'/> in an octogenarian related to dolichoectasia. Fusiform dolichoectasia is a common finding in the vertebrobasilar arteries in older patients.](images/app.statdx.com_image_38e1497f-31e3-49db-8b46-4ab561bf1eac_fb437f8b_20251018T080401Z.jpg)
**Dolichoectasia**
*Axial CT shows fusiform dilatation and tortuosity of the basilar artery <img src='img/arrows/CS.png'/> in an octogenarian related to dolichoectasia. Fusiform dolichoectasia is a common finding in the vertebrobasilar arteries in older patients.*
![Axial CT shows fusiform dilatation and tortuosity of the basilar artery <img src='img/arrows/CS.png'/> in an octogenarian related to dolichoectasia. Fusiform dolichoectasia is a common finding in the vertebrobasilar arteries in older patients.](images/app.statdx.com_image_thumbnail_38e1497f-31e3-49db-8b46-4ab561bf1eac_size_168_quality_85_e3c2ebff_20251018T080328Z.jpg)
**Dolichoectasia**
*Axial CT shows fusiform dilatation and tortuosity of the basilar artery <img src='img/arrows/CS.png'/> in an octogenarian related to dolichoectasia. Fusiform dolichoectasia is a common finding in the vertebrobasilar arteries in older patients.*
![Axial CT shows fusiform dilatation and tortuosity of the basilar artery <img src='img/arrows/CS.png'/> in an octogenarian related to dolichoectasia. Fusiform dolichoectasia is a common finding in the vertebrobasilar arteries in older patients.](images/app.statdx.com_image_thumbnail_38e1497f-31e3-49db-8b46-4ab561bf1eac_size_174_quality_85_9fba439d_20251018T080313Z.jpg)
**Dolichoectasia**
*Axial CT shows fusiform dilatation and tortuosity of the basilar artery <img src='img/arrows/CS.png'/> in an octogenarian related to dolichoectasia. Fusiform dolichoectasia is a common finding in the vertebrobasilar arteries in older patients.*
![Coronal CTA shows fusiform dilatation <img src='img/arrows/CS.png'/> of the right supraclinoid internal carotid artery (ICA). Irregularity from atherosclerotic disease can be seen of the M1 segment of the middle cerebral artery <img src='img/arrows/CO.png'/>. No significant mural thrombus was noted in this fusiform aneurysm.](images/app.statdx.com_image_thumbnail_f63a9221-71c6-4320-af66-1ed581202eb9_size_168_quality_85_8a3ae196_20251018T080328Z.jpg)
**Atherosclerotic Fusiform Aneurysm**
*Coronal CTA shows fusiform dilatation <img src='img/arrows/CS.png'/> of the right supraclinoid internal carotid artery (ICA). Irregularity from atherosclerotic disease can be seen of the M1 segment of the middle cerebral artery <img src='img/arrows/CO.png'/>. No significant mural thrombus was noted in this fusiform aneurysm.*
![Dissecting pseudoaneurysm in the V4 segment of the right vertebral artery seen on 3D TOF MRA <img src='img/arrows/WS.png'/>, T2 <img src='img/arrows/BS.png'/>, and T1 pre- <img src='img/arrows/CS.png'/> and post <img src='img/arrows/CO.png'/> DANTE VWI sequences shows peripheral enhancement, suggestive of instability.](images/app.statdx.com_image_thumbnail_68b41ae0-9f3a-4484-8b02-69d6772626db_size_168_quality_85_8d79e53e_20251018T080328Z.jpg)
**Dissecting Aneurysm/Pseudoaneurysm**
*Dissecting pseudoaneurysm in the V4 segment of the right vertebral artery seen on 3D TOF MRA <img src='img/arrows/WS.png'/>, T2 <img src='img/arrows/BS.png'/>, and T1 pre- <img src='img/arrows/CS.png'/> and post <img src='img/arrows/CO.png'/> DANTE VWI sequences shows peripheral enhancement, suggestive of instability.*
![3D MIP MRA of the vertebrobasilar arteries in a teenage female with a history of type 4 Ehlers-Danlos shows fusiform dilatation of the vertebral artery <img src='img/arrows/CS.png'/>. The affected gene is COL3A1, and this specific type of Ehlers-Danlos has a higher risk of aneurysm and vascular rupture.](9bc8ed2b-21d8-4169-949b-37b8ac0cff3b)
**Ehlers-Danlos**
*3D MIP MRA of the vertebrobasilar arteries in a teenage female with a history of type 4 Ehlers-Danlos shows fusiform dilatation of the vertebral artery <img src='img/arrows/CS.png'/>. The affected gene is COL3A1, and this specific type of Ehlers-Danlos has a higher risk of aneurysm and vascular rupture.*
![Axial MIP from CT arteriography shows fusiform dilatation of the left middle cerebral artery bifurcation <img src='img/arrows/CS.png'/> in this child with a history of Marfan syndrome.](images/app.statdx.com_image_thumbnail_9c20720f-93e4-49ad-b302-93e2d3e03a65_size_168_quality_85_2e4b9fef_20251018T080329Z.jpg)
**Marfan Syndrome**
*Axial MIP from CT arteriography shows fusiform dilatation of the left middle cerebral artery bifurcation <img src='img/arrows/CS.png'/> in this child with a history of Marfan syndrome.*
![Coronal MIP reformat from CT arteriography shows bilateral fusiform aneurysms of supraclinoid ICAs <img src='img/arrows/CS.png'/>. This patient also had thoracic aortic aneurysm, which is consistent with familial thoracic aortic aneurysm and dissection and is associated with a mutation of ACTA2. This gene is responsible for a component of vascular smooth muscle.](462595df-bda7-4ce1-a01b-74902f8a2097)
**Familial Thoracic Aneurysm &/or Dissection**
*Coronal MIP reformat from CT arteriography shows bilateral fusiform aneurysms of supraclinoid ICAs <img src='img/arrows/CS.png'/>. This patient also had thoracic aortic aneurysm, which is consistent with familial thoracic aortic aneurysm and dissection and is associated with a mutation of ACTA2. This gene is responsible for a component of vascular smooth muscle.*
![Axial T2WI MR shows strikingly enlarged middle cerebral arteries <img src='img/arrows/CS.png'/> in this child with congenital HIV/AIDS (an uncommon but well-recognized cause of pediatric fusiform arteriopathy). The stroke-like presentations of HIV infection may relate to vasculopathies, including large-vessel aneurysmal vasculopathy.](images/app.statdx.com_image_thumbnail_b62dcdb8-45c4-477b-a466-98935b57a9f5_size_168_quality_85_562a643f_20251018T080329Z.jpg)
**HIV Infection**
*Axial T2WI MR shows strikingly enlarged middle cerebral arteries <img src='img/arrows/CS.png'/> in this child with congenital HIV/AIDS (an uncommon but well-recognized cause of pediatric fusiform arteriopathy). The stroke-like presentations of HIV infection may relate to vasculopathies, including large-vessel aneurysmal vasculopathy.*
![Axial NECT demonstrates a giant serpentine aneurysm in the basilar artery <img src='img/arrows/WC.png'/> with associated mural thrombus <img src='img/arrows/CC.png'/> seen on sagittal CTA.](images/app.statdx.com_image_thumbnail_8fb2594c-2abc-43d9-84bc-b8b67664090e_size_168_quality_85_e273dd7e_20251018T080329Z.jpg)
**Giant Serpentine Aneurysm**
*Axial NECT demonstrates a giant serpentine aneurysm in the basilar artery <img src='img/arrows/WC.png'/> with associated mural thrombus <img src='img/arrows/CC.png'/> seen on sagittal CTA.*
### Additional Images
![Sagittal T1WI MR shows an elongated basilar artery with a slow-flow, thickened wall <img src='img/arrows/WS.png'/>. The apex of the tortuous basilar artery indents the hypothalamus, 3rd ventricle <img src='img/arrows/WO.png'/>.](images/app.statdx.com_image_thumbnail_5a50f257-ef7f-4680-94e0-670c586154aa_size_168_quality_85_75bc027c_20251018T080401Z.jpg)
**Dolichoectasia**
*Sagittal T1WI MR shows an elongated basilar artery with a slow-flow, thickened wall <img src='img/arrows/WS.png'/>. The apex of the tortuous basilar artery indents the hypothalamus, 3rd ventricle <img src='img/arrows/WO.png'/>.*
![Axial T2WI MR shows an elongated, tortuous basilar artery with a thickened arterial wall <img src='img/arrows/BS.png'/>, typical for atherosclerosis-associated fusiform ectasia.](images/app.statdx.com_image_thumbnail_b0b88e99-082c-43e8-88d1-21dbf84262c4_size_168_quality_85_7b35a214_20251018T080401Z.jpg)
**Dolichoectasia**
*Axial T2WI MR shows an elongated, tortuous basilar artery with a thickened arterial wall <img src='img/arrows/BS.png'/>, typical for atherosclerosis-associated fusiform ectasia.*
![Lateral angiography shows a large fusiform middle cerebral artery aneurysm <img src='img/arrows/BS.png'/> that extends into smaller, more distal branches <img src='img/arrows/BO.png'/>. This is an unusual example because of the location (ICA, middle cerebral artery).](5b2eae83-b875-4f2c-9903-07a167a394a0)
**Atherosclerotic Fusiform Aneurysm**
*Lateral angiography shows a large fusiform middle cerebral artery aneurysm <img src='img/arrows/BS.png'/> that extends into smaller, more distal branches <img src='img/arrows/BO.png'/>. This is an unusual example because of the location (ICA, middle cerebral artery).*
![Axial T1WI MR shows an enlarged right vertebral artery with high signal intensity <img src='img/arrows/WS.png'/> as well as an absent flow void of the left vertebral artery <img src='img/arrows/WC.png'/>.](images/app.statdx.com_image_thumbnail_c349506a-b897-4a04-9191-85e5090f0d6e_size_168_quality_85_37c748bd_20251018T080328Z.jpg)
**Nonaneurysmal Dissection**
*Axial T1WI MR shows an enlarged right vertebral artery with high signal intensity <img src='img/arrows/WS.png'/> as well as an absent flow void of the left vertebral artery <img src='img/arrows/WC.png'/>.*
![Anteroposterior oblique view of the left vertebral angiogram shows focal elongations and widening of the basilar artery <img src='img/arrows/BS.png'/> in a 6-year-old child with Ehlers-Danlos type 4.](images/app.statdx.com_image_thumbnail_184ad0e5-e723-4b46-babc-4d119e6e3cab_size_168_quality_85_0cd5001e_20251018T080329Z.jpg)
**Ehlers-Danlos Syndrome**
*Anteroposterior oblique view of the left vertebral angiogram shows focal elongations and widening of the basilar artery <img src='img/arrows/BS.png'/> in a 6-year-old child with Ehlers-Danlos type 4.*
![Axial MRA submentovertex view shows an unusual nonatherosclerotic giant serpentine fusiform aneurysm. The patent channel <img src='img/arrows/WS.png'/> lies within the clot in the partially thrombosed <img src='img/arrows/WO.png'/> lumen.](7f57c3ee-7bcb-4bc3-b6b2-e96f1717613a)
**Giant Serpentine Aneurysm**
*Axial MRA submentovertex view shows an unusual nonatherosclerotic giant serpentine fusiform aneurysm. The patent channel <img src='img/arrows/WS.png'/> lies within the clot in the partially thrombosed <img src='img/arrows/WO.png'/> lumen.*
![Lateral angiography in 30-year-old man with a subarachnoid hemorrhage shows an elongated, bizarre-appearing, multilobulated aneurysm <img src='img/arrows/BS.png'/> with long aspect ratio, tit-like projections.](images/app.statdx.com_image_thumbnail_9ca263bc-486c-4775-b315-df4cbc180a32_size_168_quality_85_2d099724_20251018T080355Z.jpg)
**Atypical Saccular Aneurysm**
*Lateral angiography in 30-year-old man with a subarachnoid hemorrhage shows an elongated, bizarre-appearing, multilobulated aneurysm <img src='img/arrows/BS.png'/> with long aspect ratio, tit-like projections.*