Lentiform Fork sign: A unique MRI picture. Is metabolic acidosis responsible?

Uremic Encephalopathy: MR Imaging Findings and Clinical Correlation

“…These findings are different from the results of a literature review that showed that metabolic acidosis is the basis of the LFS, and the absence of LFS might be reflective of a normal pH. 1 We propose that the LFS can be seen in UE regardless of the presence of metabolic acidosis, though coexistent metabolic acidosis may exacerbate the damage of neurons in the basal ganglia.…”

“…The LFS has been described on T2WI/FLAIR images as a hyperintense rim delineating the lateral (external capsule) and medial (internal capsule, internal and external medullary laminae) boundaries of both putamina, resembling a fork (Fig 1B). 1 A literature review 1 reported that the LFS was found in only 1 of 21 patients with UE admitted during a 10-year period in a retrospective single-institution study, without note of the absence or presence of DM. However, data from the same literature review showed that 10 of 11 patients with UE who had the LFS had diabetes, and 1 patient with diabetic ketoacidosis had the LFS, implicating diabetes in the production of these characteristic lentiform lesions.…”

“…The LFS may also be present in metabolic acidosis from any cause, including end-stage renal disease, methanol intoxication, and the dialysis disequilibrium syndrome. [1][2][3][4][5][6] This study was undertaken to describe the MR imaging features in the brains of 10 patients with UE, with the aim of identifying common imaging features and potentially clarifying the possible pathophysiology of UE.…”

Lentiform Fork Sign: A Magnetic Resonance Finding in a Case of Acute Metabolic Acidosis

“…Conventional MRI demonstrated bilateral putaminal necrosis with a haemorrhagic component in association with another sign recently called lentiform fork sign. Kumar et al 3 described the constitutive elements of the lentiform fork: 1) the lateral arm, formed by the oedematous external capsule and extending from the anterior end of the putamen to the stem; 2) the stem, created by merging oedematous external and internal capsules at the infero-posterior end of the putamen; 3) the medial arm extended from the stem anteriorly up to one third of the medial edge where it split into two slightly less T2/FLAIR hyperintense branches engulfing the globus pallidus. These two branches are constituted by the oedematous medullary laminae, which divide the lentiform nucleus into three masses (the putamen, globus pallidus interna and externa).…”

“…Uremic encephalopathy, diabetes mellitus, methanol and ethylene glycol intoxications, acidopathies such as propionic acidaemia (PA) and pyruvate dehydrogenase deficiency were commonly associated with metabolic acidosis. Literature reviews [3][4][5][6][7][8][9][10][11] demonstrated that these conditions were also related to a lentiform fork appearance. Methanol is a clear colourless toxic liquid, commonly found in many commercial products of daily use like solvents, antifreeze, varnish and cleaning fluids.…”