====== Intracranial Aneurysm Diagnosis ====== Early and accurate diagnosis is critical for management and prevention of complications. ===== 1. Clinical Presentation ===== Patients with an intracranial aneurysm may present with: * **Asymptomatic** (incidental finding in imaging) * **Warning signs** (sentinel headaches, cranial nerve palsies) * **Acute rupture** → **Subarachnoid Hemorrhage (SAH)** - Sudden, severe "thunderclap" headache - Nausea, vomiting - Photophobia, neck stiffness (meningeal irritation) - Altered consciousness, seizures - Focal neurological deficits (depending on aneurysm location) ===== 2. Imaging Modalities ===== Different imaging techniques are used for **aneurysm detection and characterization**. ^ Imaging Technique ^ Sensitivity ^ Specificity ^ Advantages ^ Limitations ^ | **Computed Tomography Angiography (CTA)** | 85-95% | 90-98% | Rapid, non-invasive, good for screening | Lower resolution for small aneurysms (<3mm), bone artifacts | | **Multiphase CTA (MP-CTA)** | High | High | Improves detection in slow-flow aneurysms | Lacks dynamic flow assessment | | **Magnetic Resonance Angiography (MRA)** | 85-95% | High | No radiation, good for follow-up | Longer acquisition time, motion artifacts | | **Digital Subtraction Angiography (DSA)** | Nearly 100% | Nearly 100% | Gold standard, dynamic blood flow assessment | Invasive, risk of stroke/vascular injury | | **Non-Contrast CT (NCCT)** | Low | High for SAH | Best for acute SAH detection | Cannot visualize unruptured aneurysms | ===== 3. When to Use Each Modality ===== * **First-line screening** → **CTA or MRA** * **Acute SAH suspicion** → **NCCT**, followed by **CTA** * **Definitive diagnosis** (unclear cases, pre-surgical planning) → **DSA** * **Long-term follow-up** → **MRA (preferred for radiation avoidance), CTA if needed** ===== 4. Risk Factors for Aneurysm Development ===== * **Genetic predisposition** (family history, connective tissue disorders) * **Hypertension** * **Smoking** * **Excessive alcohol consumption** * **Female sex, postmenopausal status** * **Previous SAH or multiple aneurysms** * **Polycystic kidney disease (PKD)** ===== 5. Management Considerations ===== * **Small, unruptured aneurysms (<5mm)**: Conservative management, risk factor control, follow-up imaging * **Aneurysms ≥5mm or symptomatic**: Endovascular (coiling) or surgical (clipping) intervention * **Ruptured aneurysm**: Urgent **aneurysm occlusion** and **SAH management** (ICU care, BP control, vasospasm prevention) ===== 6. Conclusion ===== Intracranial aneurysm diagnosis requires a **multi-modal imaging approach** based on clinical presentation. **CTA and MRA** are useful for screening, while **DSA remains the gold standard** for definitive evaluation and treatment planning. ===== Screening ===== The low 1.14% per-person year risk of DNIA detection and small DNIA size at detection cannot justify routine screening for DNIAs in all patients with a personal history of IAs. If imaging follow-up is considered for selected patients, early screening will likely yield the most benefit in patients who continue to smoke cigarettes ((Wang JY, Smith R, Ye X, Yang W, Caplan JM, Radvany MG, Colby GP, Coon AL, Tamargo RJ, Huang J. Serial Imaging Surveillance for Patients With a History of Intracranial Aneurysm: Risk of De Novo Aneurysm Formation. Neurosurgery. 2015 Jul;77(1):32-43. doi: 10.1227/NEU.0000000000000730. PubMed PMID: 25790068.)). ---- Since its introduction, [[digital subtraction angiography]] has been considered the gold standard in diagnostic imaging for neurovascular disease. Modern post-processing techniques have made angiography even more informative to the cerebrovascular neurosurgeon or neurointerventionalist. In patients with a head computed tomography scan performed less than 6 h after headache onset and reported negative by a staff radiologist, lumbar puncture can be withheld. ((Rinkel GJ. Management of patients with aneurysmal subarachnoid haemorrhage. Curr Opin Neurol. 2016 Feb;29(1):37-41. doi: 10.1097/WCO.0000000000000282. PubMed PMID: 26641816. )). Intracranial vascular lesions, such as a vascular loop, infundibulum, and stump of an occluded vessel, are sometimes misdiagnosed as aneurysms during imaging examinations (( Park J, Baik SK, Kim Y, Hamm IS. Occluded vascular stump mimicking middle cerebral artery bifurcation aneurysm: report of 2 cases. Surg Neurol. 2008;70(6):664–667.)). It is difficult to differentiate such lesions from aneurysms on the basis of imaging findings ((Komiyama M, Ishiguro T, Morikawa T, Nishikawa M, Yasui T. Distal stump of an occluded intracranial vertebral artery at the vertebrobasilar junction mimicking a basilar artery aneurysm. Acta Neurochir (Wien) 2001;143(10):1013–1017.)) ((Nakano S, Yokogami K, Ohta H, Wakisaka S. A Stump of Occluded Posterior Cerebral Artery Mimicking a Ruptured Aneurysm: Case Report. Int J Angiol. 2000;9(1):51–52.)). ---- For [[Aneurysmal subarachnoid hemorrhage]] [[diagnosis]] in the early phase, during the first 24 hours, [[cerebral CT]], combined with intracranial [[CT angiography]] is recommended to make a positive diagnosis of [[SAH]], to identify the cause and to investigate for an [[intracranial aneurysm]]. [[Cranial magnetic resonance imaging ]] may be proposed if the patient's clinical condition allows it. [[FLAIR]] imaging is more sensitive than CT to demonstrate a subarachnoid hemorrhage and offers greater degrees of sensitivity for the diagnosis of restricted subarachnoid hemorrhage in [[cortical sulcus]]. A [[lumbar puncture]] should be performed if these investigations are normal while clinical suspicion is high ((Edjlali M, Rodriguez-Régent C, Hodel J, Aboukais R, Trystram D, Pruvo JP, Meder JF, Oppenheim C, Lejeune JP, Leclerc X, Naggara O. Subarachnoid hemorrhage in ten questions. Diagn Interv Imaging. 2015 Jul-Aug;96(7-8):657-66. doi: 10.1016/j.diii.2015.06.003. Epub 2015 Jul 2. PubMed PMID: 26141485. )). CT angiography is an appropriate initial investigation to detect macrovascular causes of non-traumatic Intracerebral hemorrhage, but accuracy is modest. Additional MRI/MRA may find cavernomas or alternative diagnoses, but DSA is needed to diagnose macrovascular causes undetected by CT angiography or MRI/MRA ((van Asch CJ, Velthuis BK, Rinkel GJ, Algra A, de Kort GA, Witkamp TD, de Ridder JC, van Nieuwenhuizen KM, de Leeuw FE, Schonewille WJ, de Kort PL, Dippel DW, Raaymakers TW, Hofmeijer J, Wermer MJ, Kerkhoff H, Jellema K, Bronner IM, Remmers MJ, Bienfait HP, Witjes RJ, Greving JP, Klijn CJ; DIAGRAM Investigators. Diagnostic yield and accuracy of CT angiography, MR angiography, and digital subtraction angiography for detection of macrovascular causes of intracerebral haemorrhage: prospective, multicentre cohort study. BMJ. 2015 Nov 9;351:h5762. doi: 10.1136/bmj.h5762. PubMed PMID: 26553142; PubMed Central PMCID: PMC4637845.)). ===== Spinal magnetic resonance imaging ===== The yield and clinical relevance of MRI of the spinal axis in patients who present with nonperimesencephalic subarachnoid hemorrhage (NPSAH) is low. Germans et al. do not recommend routine MRI of the spinal axis in this patient population, but it might be justified in a subgroup of patients ((Germans MR, Coert BA, Majoie CB, van den Berg R, Lycklama À Nijeholt G, Rinkel GJ, Verbaan D, Vandertop WP. Yield of spinal imaging in nonaneurysmal, nonperimesencephalic subarachnoid hemorrhage. Neurology. 2015 Mar 31;84(13):1337-40. doi: 10.1212/WNL.0000000000001423. Epub 2015 Feb 27. PubMed PMID: 25724231. )). The yield and clinical relevance of MRI of the spinal axis in patients who present with NPSAH is low. Germans et al. do not recommend routine MRI of the spinal axis in this patient population, but it might be justified in a subgroup of patients ((Germans MR, Coert BA, Majoie CB, van den Berg R, Lycklama À Nijeholt G, Rinkel GJ, Verbaan D, Vandertop WP. Yield of spinal imaging in nonaneurysmal, nonperimesencephalic subarachnoid hemorrhage. Neurology. 2015 Mar 31;84(13):1337-40. doi: 10.1212/WNL.0000000000001423. Epub 2015 Feb 27. PubMed PMID: 25724231. )) ((Germans MR, Coert BA, Majoie CB, van den Berg R, Verbaan D, Vandertop WP. Spinal axis imaging in non-aneurysmal subarachnoid hemorrhage: a prospective cohort study. J Neurol. 2014 Nov;261(11):2199-203. doi: 10.1007/s00415-014-7480-y. Epub 2014 Sep 3. PubMed PMID: 25182702.)). ===== Computed tomography angiography ===== see [[Computed tomography angiography for subarachnoid hemorrhage]]. ===== Cerebral angiography ===== [[Cerebral angiography for subarachnoid hemorrhage]] ^ Feature ^ Multiphase CT Angiography (MP-CTA) ^ Digital Subtraction Angiography (DSA) ^ | **Sensitivity** | 85-95% (lower for small aneurysms) | Nearly 100% (gold standard) | | **Specificity** | 90-98% | Nearly 100% | | **Invasiveness** | Non-invasive | Invasive (catheter-based) | | **Risk of complications** | Minimal (radiation & contrast risks) | Higher (stroke, vessel injury, hematoma) | | **Imaging speed** | Fast (minutes) | Longer procedure | | **Visualization of small aneurysms (<3mm)** | Limited accuracy | Superior resolution | | **Dynamic flow assessment** | No (static images) | Yes (real-time blood flow visualization) | | **Artifact issues** | Bone & vessel overlap may affect clarity | Minimal artifacts | | **Best for...** | Screening, emergency cases, preoperative planning in some cases | Definitive diagnosis, pre-surgical/endovascular planning | | **Limitations** | May miss small/complex aneurysms, no dynamic blood flow info | Requires arterial access, risk of complications | see [[Subarachnoid hemorrhage diagnosis]]. ---- Although intracranial arterial aneurysms (IAAs) of childhood are usually idiopathic, it is possible that underlying arteriopathy escapes detection when using conventional diagnostic tools. Quantitative arterial tortuosity (QAT) has been studied as a biomarker of arteriopathy. The authors analyzed cervicocerebral QAT in children with idiopathic IAAs to assess the possibility of arteriopathy. METHODS: Cases were identified by text-string searches of imaging reports spanning the period January 1993 through June 2017. QAT of cervicocerebral arterial segments was measured from cross-sectional studies using image-processing software. Other imaging and clinical data were confirmed by retrospective electronic record review. Children with idiopathic IAAs and positive case controls, with congenital arteriopathy differentiated according to aneurysm status (with and without an aneurysm), were compared to each other and to healthy controls without vascular risk factors. RESULTS: Cervicocerebral QAT was measured in 314 children: 24 with idiopathic IAAs, 163 with congenital arteriopathy (including 14 arteriopathic IAAs), and 127 healthy controls. QAT of all vertebrobasilar segments was larger in children with IAAs (idiopathic and arteriopathic forms) (p < 0.05). In children with congenital arteriopathy without an aneurysm, QAT was decreased for the distal cervical vertebral arteries and increased for the supraspinal vertebral artery relative to healthy children. QAT of specific cervicocerebral segments correlated with IAA size and rupture status. CONCLUSIONS: Cervicocerebral QAT is a biomarker of arteriopathy in children with IAA, even in the absence of other disease markers. Additional findings suggest a correlation of cervicocerebral QAT with IAA size and rupture status and with the presence of IAA in children with congenital arteriopathy ((Chen AM, Karani KB, Taylor JM, Zhang B, Furthmiller A, De Vela G, Leach JL, Vadivelu S, Abruzzo TA. Cervicocerebral quantitative arterial tortuosity: a biomarker of arteriopathy in children with intracranial aneurysms. J Neurosurg Pediatr. 2019 Jul 26:1-8. doi: 10.3171/2019.5.PEDS1982. [Epub ahead of print] PubMed PMID: 31349231. )). ===== Cerebral angiography for intracranial aneurysm ===== [[Cerebral angiography for intracranial aneurysm]]. ===== Magnetic resonance angiography for intracranial aneurysm ===== [[Magnetic resonance angiography for intracranial aneurysm]]