HomeRadiologyVol. 307, No. 1 PreviousNext Reviews and CommentaryFree AccessImages in RadiologyUremic EncephalopathyDavid A. Lizarazo , Jairo LizarazoDavid A. Lizarazo , Jairo LizarazoAuthor AffiliationsFrom the Department of Diagnostic Imaging, Fundación Santa Fe de Bogotá, Universidad El Bosque, Ave 116 No. 9-02, Bogotá 110246, Colombia (D.A.L.); and Department of Internal Medicine, Hospital Universitario Erasmo Meoz, Universidad de Pamplona, Cúcuta, Colombia (J.L.).Address correspondence to D.A.L. (email: [email protected]).David A. Lizarazo Jairo LizarazoPublished Online:Dec 20 2022https://doi.org/10.1148/radiol.221602MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In A 54-year-old man was admitted for a 3-day history of dysarthria, hand tremors, hypokinesia, and generalized muscle rigidity. His past medical history included diabetes mellitus and end-stage renal disease on hemodialysis. On admission, there were elevated blood urea nitrogen and creatinine levels with a metabolic acidosis. Axial CT scan of the brain showed symmetrical hypoattenuation of both basal ganglia (Figure). Noncontrast brain T2-weighted MRI demonstrated symmetrical high signal intensity in the basal ganglia surrounded by a more hyperintense rim delineating the lentiform nucleus (Figure). This is the lentiform fork sign, wherein the internal and external capsules and the medullary laminae become hyperintense with axial T2-weighted images (Figure). After correction of the metabolic acidosis with prompt dialysis and glycemic control, the neurologic examination returned to normal, and his symptoms completely resolved. A follow-up MRI examination was not performed.Images in a 54-year-old man who presented with a 3-day evolution of dysarthria, hand tremors, hypokinesia, and generalized muscle rigidity. He had diabetes mellitus and end-stage renal disease and was undergoing hemodialysis. Laboratory tests showed azotemia and metabolic acidosis. (A) Axial CT scan of brain shows symmetrical hypoattenuation in the bilateral basal ganglia. (B) Axial T2-weighted fluid-attenuated inversion recovery noncontrast brain MRI scan demonstrates bilateral symmetrical swollen lentiform nuclei with a hyperintense rim delineating the lentiform nucleus with a typical fork-like appearance representing the “lentiform fork sign.” (C) Schematic drawing shows the “lentiform fork sign.” At follow-up after correction of metabolic acidosis with prompt dialysis and glycaemic control, the neurologic examination was normal, and symptoms completely resolved. Follow-up scan was not performed. EC = external capsule, IC = internal capsule, LME = external medullary lamina, LMI = internal medullary lamina, TS = the stem.Download as PowerPointOpen in Image Viewer Uremic encephalopathy is a neurologic complication resulting from endogenous uremic toxins in patients with severe renal failure. The pathogenesis is complex and unclear (1). The lentiform fork sign (Figure) is attributed to metabolic acidosis in patients with diabetes and renal failure with a history of incomplete dialysis leading to reversible basal ganglia and adjacent white matter injury (2). The edematous external capsule represents the lateral arm of the fork, with both the external and internal capsule joining to build the stem of the fork. Edema of the medial lentiform margin forms the medial arm, which splits into two along the medullary laminae to envelop the globus pallidus (3). The lentiform fork sign is nonspecific for uremic encephalopathy. Differential diagnosis of pathologic conditions manifesting with this sign includes severe metabolic acidosis, ketoacidosis, dialysis disequilibrium syndrome, and intoxication (ie, methanol, ethylene glycol); this can also be drug induced (ie, metformin) (4).Disclosures of conflicts of interest: D.A.L. No relevant relationships. J.L. No relevant relationships.
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Oct 1, 2024
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