Autoimmune Encephalitis echocardiography or ultrasound
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Julinka Auta Fernandes
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Overview
Autoimmune encephalitis has no characteristic echocardiographic or ultrasound finding that establishes the neurological diagnosis. Ultrasound is principally used to investigate associated tumors, particularly an ovarian teratoma in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Echocardiography is used selectively when cardiac disease is suspected, rather than as a diagnostic test for autoimmune encephalitis.[1][2]
Key Echocardiography/Ultrasound Findings in Autoimmune Encephalitis
Pelvic Ultrasound
In autoimmune encephalitis, pelvic ultrasound is particularly important when the clinical syndrome or antibody results suggest an associated ovarian teratoma. Transabdominal or transvaginal ultrasound may be used, with the approach selected according to age, clinical circumstances, suitability, and consent. Magnetic resonance imaging (MRI) of the pelvis may clarify an equivocal ultrasound examination.[1]
A mature cystic teratoma may show:
- Focal or diffuse hyperechoic components with posterior acoustic shadowing.
- Other characteristic internal features, such as echogenic lines and dots.
These appearances reflect the tumor's contents, not inflammation of the brain. The American College of Radiology's updated ovarian-adnexal ultrasound reporting guidance describes the shadowing hyperechoic component as a typical dermoid feature.[3][4]
Finding an ovarian mass does not by itself diagnose autoimmune encephalitis, and a normal ultrasound does not exclude an associated tumor. Further imaging and specialist review depend on the clinical and antibody-associated risk. Management of a potentially relevant teratoma in encephalitis should follow the neurological and gynecological assessment; routine surveillance recommendations for incidental asymptomatic ovarian cysts should not automatically be applied.[5]
Testicular Ultrasound
In autoimmune encephalitis, testicular ultrasound is used when a testicular germ-cell tumor is suspected from the clinical syndrome, age, examination, or antibody association. Examples include antibodies against paraneoplastic antigen Ma2 or Kelch-like protein 11 (KLHL11).[1][5]
Ultrasound assesses for an intratesticular lesion, but neither an abnormality nor its absence establishes or excludes the neurological diagnosis. A normal examination should be interpreted within the broader tumor-screening plan rather than treated as proof that paraneoplastic disease is absent.[5]
Echocardiography
In autoimmune encephalitis, echocardiography does not assess brain inflammation or neuronal antibodies. It can be considered when there is a separate clinical concern for cardiac involvement, such as suspected heart failure, cardiogenic shock, or myocarditis. This is an application of cardiac diagnostic guidance, not a routine autoimmune encephalitis diagnostic criterion.[2]
If myocarditis is suspected, echocardiography may demonstrate impaired ventricular function, regional wall-motion abnormalities, or associated pericardial involvement. These findings are not specific to autoimmune encephalitis. A normal echocardiogram does not exclude myocarditis when clinical suspicion remains high.[2]
Heart-rate fluctuations from dysautonomia require rhythm assessment with electrocardiography and, when indicated, continuous cardiac monitoring. Echocardiography assesses cardiac structure and function and does not replace rhythm monitoring.[1]
Children
In pediatric autoimmune encephalitis, tumor investigation should be tailored to the syndrome and age. The international consensus for pediatric NMDAR antibody encephalitis recommends early oncological screening, using ultrasound or MRI of the abdomen and pelvis and appropriate chest imaging. Screening for neural crest tumors is relevant in children younger than five years.[7]
The consensus emphasizes reassessment for tumors in patients who fail to improve or relapse, with particular attention to ovarian teratoma surveillance in postpubertal females. These recommendations concern pediatric NMDAR antibody encephalitis and should not be automatically generalized to every childhood encephalitis syndrome.[7]
Limitations and Follow-Up
In autoimmune encephalitis, targeted ultrasound complements rather than replaces the broader neoplasm investigation. The 2024 Canadian adult consensus recommends initial tumor screening without waiting for antibody results; the investigations may include body computed tomography (CT), directed imaging, and selected whole-body positron emission tomography.[5]
Follow-up depends on antibody-associated risk, clinical phenotype, response to treatment, relapse, and other cancer risk factors. A single normal ultrasound is not a reason to stop further investigation when suspicion remains high, and there is no single ultrasound surveillance schedule appropriate for all patients.[5]
References
- ↑ 1.0 1.1 1.2 1.3 Abboud H, Probasco JC, Irani S, et al. Autoimmune encephalitis: proposed best practice recommendations for diagnosis and acute management. Journal of Neurology, Neurosurgery & Psychiatry. 2021;92(7):757–768. doi:10.1136/jnnp-2020-325300. PMID:33649022.
- ↑ 2.0 2.1 2.2 American College of Cardiology. 2024 ACC Expert Consensus Decision Pathway on Strategies and Criteria for the Diagnosis and Management of Myocarditis: A Report of the American College of Cardiology Solution Set Oversight Committee. doi:10.1016/j.jacc.2024.10.080. PMID:39665703.
- ↑ American College of Radiology Ovarian-Adnexal Reporting and Data System Ultrasound Committee. O-RADS US v2022: An Update from the American College of Radiology's Ovarian-Adnexal Reporting and Data System US Committee. Radiology. 2023;308(3):e230685. doi:10.1148/radiol.230685. PMID:37698472.
- ↑ Levine D, Brown DL, Andreotti RF, et al. Management of Asymptomatic Ovarian and Other Adnexal Cysts Imaged at US: Society of Radiologists in Ultrasound Consensus Conference Statement. Radiology. 2010;256(3):943–954. doi:10.1148/radiol.10100213.
- ↑ 5.0 5.1 5.2 5.3 5.4 Hahn C, Budhram A, Alikhani K, et al. Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults. Canadian Journal of Neurological Sciences. 2024;51(6):734–754. doi:10.1017/cjn.2024.16. PMID:38312020.
- ↑ Heilman J. ComplexCystofaDermoid.png. Wikimedia Commons. May 31, 2016. Original work. Licensed under Creative Commons Attribution–ShareAlike 4.0. Accessed November 4, 2026.
- ↑ 7.0 7.1 Nosadini M, Thomas T, Eyre M, et al. International Consensus Recommendations for the Treatment of Pediatric NMDAR Antibody Encephalitis. Neurology: Neuroimmunology & Neuroinflammation. 2021;8(5):e1052. doi:10.1212/NXI.0000000000001052. PMID:34301820.