{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T07:37:35Z","timestamp":1773041855128,"version":"3.50.1"},"reference-count":13,"publisher":"Scientific Scholar","content-domain":{"domain":["clinicalimagingscience.org"],"crossmark-restriction":true},"short-container-title":["JCIS"],"abstract":"<jats:p>Lesions involving the region immediately posterior to the splenium of the corpus callosum have traditionally been associated with \u201cretrosplenial amnesia.\u201d However, the crus of the fornix (FxCr), which runs immediately beneath the splenium, is anatomically vulnerable to secondary involvement that may be overlooked on conventional magnetic resonance imaging (MRI). Because the fornix constitutes a critical efferent pathway of the hippocampal Papez circuit, disruption of the FxCr can contribute to amnesia that may resemble the effects of retrosplenial cortical dysfunction. This possibility was raised in the original single-case description of \u201cretrosplenial amnesia,\u201d although direct assessment of the fornix was not feasible with the imaging techniques available at that time.\u201d We report an adult who developed episodic memory impairment following a splenial region hemorrhage with intraventricular extension. Formal neuropsychological assessment demonstrated profound anterograde amnesia with preservation of other cognitive functions, indicating selective impairment of episodic memory. Initial conventional MRI demonstrated that the hemorrhage was confined to the splenium of the corpus callosum, without definite involvement of the retrosplenial cortex. On follow-up imaging, high-resolution 3D T1-weighted MRI with multiplanar reconstruction revealed focal discontinuity of the left FxCr immediately beneath the splenial lesion with chronic encephalomalacia, while the hippocampi and medial temporal structures remained structurally intact. I-123 IMP single photon emission computed tomography showed hypoperfusion in the left hippocampus and the anterior and posterior cingulate gyri, without significant hypoperfusion in the retrosplenial region, consistent with downstream functional disruption of the Papez circuit secondary to FxCr disconnection. These findings provide contemporary structural and functional evidence that injury to the FxCr may represent a critical substrate of amnesia previously attributed primarily to retrosplenial lesions. Routine evaluation of the fornix, particularly the FxCr, should be incorporated into the diagnostic assessment of patients with splenial or retrosplenial pathology accompanied by amnesia.<\/jats:p>","DOI":"10.25259\/jcis_286_2025","type":"journal-article","created":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T06:47:16Z","timestamp":1773038836000},"page":"10","update-policy":"https:\/\/doi.org\/10.25259\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Revisiting retrosplenial amnesia: Injury of the crus of the fornix following splenial hemorrhage \u2013 A 3D magnetic resonance imaging case report"],"prefix":"10.25259","volume":"16","author":[{"given":"Shunji","family":"Mugikura","sequence":"first","affiliation":[{"name":"Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Sendai, Japan,"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Naoko","family":"Mori","sequence":"additional","affiliation":[{"name":"Department of Radiology, Akita University Graduate School of Medicine, Akita, Japan,"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"10894","published-online":{"date-parts":[[2026,3,9]]},"reference":[{"key":"10.25259\/JCIS_286_2025\/ref-1","doi-asserted-by":"publisher","first-page":"225","DOI":"10.1111\/1467-9450.00233","article-title":"The retrosplenial contribution to human navigation: A review of lesion and neuroimaging findings","volume":"42","author":"Maguire","year":"2001","journal-title":"Scand J Psychol"},{"key":"10.25259\/JCIS_286_2025\/ref-2","doi-asserted-by":"publisher","first-page":"563","DOI":"10.1007\/s00234-019-02357-z","article-title":"The splenium of the corpus callosum: Embryology, anatomy, function and imaging with pathophysiological hypothesis","volume":"62","author":"Blaauw","year":"2020","journal-title":"Neuroradiology"},{"key":"10.25259\/JCIS_286_2025\/ref-3","doi-asserted-by":"publisher","first-page":"102","DOI":"10.1016\/S0303-8467(97)80005-4","article-title":"Amnesia following infarction in the right retrosplenial region","volume":"99","author":"Yasuda","year":"1997","journal-title":"Clin Neurol Neurosurg"},{"key":"10.25259\/JCIS_286_2025\/ref-4","doi-asserted-by":"publisher","first-page":"1631","DOI":"10.1093\/brain\/110.6.1631","article-title":"Retrosplenial amnesia","volume":"110","author":"Valenstein","year":"1987","journal-title":"Brain"},{"key":"10.25259\/JCIS_286_2025\/ref-5","doi-asserted-by":"publisher","first-page":"441","DOI":"10.1016\/j.jstrokecerebrovasdis.2013.03.026","article-title":"Retrosplenial amnesia without topographic disorientation caused by a lesion in the nondominant hemisphere","volume":"23","author":"Maeshima","year":"2014","journal-title":"J Stroke Cerebrovasc Dis"},{"key":"10.25259\/JCIS_286_2025\/ref-6","doi-asserted-by":"publisher","first-page":"2293","DOI":"10.3174\/ajnr.A4057","article-title":"MR imaging of subcallosal artery infarct causing amnesia after surgery for anterior communicating artery aneurysm","volume":"35","author":"Mugikura","year":"2014","journal-title":"AJNR Am J Neuroradiol"},{"key":"10.25259\/JCIS_286_2025\/ref-7","doi-asserted-by":"publisher","first-page":"81","DOI":"10.1007\/s11604-017-0703-2","article-title":"Subcallosal and Heubner artery infarcts following surgical repair of an anterior communicating artery aneurysm: A causal relationship with postoperative amnesia and long-term outcome","volume":"36","author":"Mugikura","year":"2018","journal-title":"Jpn J Radiol"},{"key":"10.25259\/JCIS_286_2025\/ref-8","doi-asserted-by":"publisher","first-page":"59","DOI":"10.1620\/tjem.2025.J006","article-title":"Language registration-based scoring system for handwritten logical memory of the Wechsler Memory Scale-Revised: Developed and validated in the Tohoku Medical Megabank Project","volume":"267","author":"Mori","year":"2025","journal-title":"Tohoku J Exp Med"},{"key":"10.25259\/JCIS_286_2025\/ref-9","doi-asserted-by":"publisher","first-page":"731","DOI":"10.1097\/MNM.0b013e328013eb8b","article-title":"Automated discrimination between very early Alzheimer disease and controls using an easy Z-score imaging system for multicenter brain perfusion single-photon emission tomography","volume":"28","author":"Matsuda","year":"2007","journal-title":"AJNR Am J Neuroradiol"},{"key":"10.25259\/JCIS_286_2025\/ref-10","doi-asserted-by":"publisher","first-page":"834","DOI":"10.1038\/nn.2149","article-title":"A disproportionate role for the fornix and mammillary bodies in recall versus recognition memory","volume":"11","author":"Tsivilis","year":"2008","journal-title":"Nat Neurosci"},{"key":"10.25259\/JCIS_286_2025\/ref-11","doi-asserted-by":"publisher","first-page":"757","DOI":"10.1007\/s00234-015-1504-x","article-title":"Infarction in the pars libera of the column of fornix including pre (cholinergic)-and post (circuit of Papez fiber tracts)-commissural fibers causes \u201cbasal forebrain\u201d amnesia","volume":"57","author":"Mugikura","year":"2015","journal-title":"Neuroradiology"},{"key":"10.25259\/JCIS_286_2025\/ref-12","doi-asserted-by":"publisher","first-page":"515","DOI":"10.1007\/s00234-019-02158-4","article-title":"Atrophy of the ipsilateral mammillary body in unilateral hippocampal sclerosis shown by thin-slice-reconstructed volumetric analysis","volume":"61","author":"Morishita","year":"2019","journal-title":"Neuroradiology"},{"key":"10.25259\/JCIS_286_2025\/ref-13","doi-asserted-by":"publisher","first-page":"38","DOI":"10.25259\/JCIS_77_2023","article-title":"Interhemispheric asymmetrical change in gray matter volume in patients with unilateral hippocampal sclerosis","volume":"13","author":"Mugikura","year":"2023","journal-title":"J Clin Imaging Sci"}],"container-title":["Journal of Clinical Imaging Science"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/clinicalimagingscience.org\/revisiting-retrosplenial-amnesia-injury-of-the-crus-of-the-fornix-following-splenial-hemorrhage-a-3d-magnetic-resonance-imaging-case-report\/","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/clinicalimagingscience.org\/revisiting-retrosplenial-amnesia-injury-of-the-crus-of-the-fornix-following-splenial-hemorrhage-a-3d-magnetic-resonance-imaging-case-report\/","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T06:47:16Z","timestamp":1773038836000},"score":1,"resource":{"primary":{"URL":"https:\/\/clinicalimagingscience.org\/revisiting-retrosplenial-amnesia-injury-of-the-crus-of-the-fornix-following-splenial-hemorrhage-a-3d-magnetic-resonance-imaging-case-report\/"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,9]]},"references-count":13,"alternative-id":["10.25259\/JCIS_286_2025"],"URL":"https:\/\/doi.org\/10.25259\/jcis_286_2025","relation":{},"ISSN":["2156-5597","2156-7514"],"issn-type":[{"value":"2156-5597","type":"electronic"},{"value":"2156-7514","type":"print"}],"subject":[],"published":{"date-parts":[[2026,3,9]]},"article-number":"10"}}