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Key Clinical Message: A novel radiologic sign in patients with renal failure and uremic encephalopathy (UE) with metabolic acidosis has recently been identified as the lentiform fork sign. On magnetic resonance imaging (MRI), the "lentiform fork sign" has been described as bilateral symmetrical hyperintensities in the basal ganglia encircled by a hyperintese rim delineating the lentiform nucleus. Changes in uremic solute retention, aberrant blood–brain barrier transport, disordered vascular reactivity, altered electrolyte and acid–base balance, and altered hormone metabolism are the most likely causes of the condition. A 56‐year‐old male with end‐stage renal disease was brought to the emergency room for a progressive change in mental status and involuntary arm movements over the previous 5 days, which were accompanied by mild dyspnea. A brain MRI was performed, and it revealed hyperintensity on T2/FLAIR in the white matter surrounding the basal ganglia. the patient was treated with dialysis and improved greatly. Intensified hemodialysis and glycemic control are the cornerstones of treating diabetic uremic syndrome (DUS) with likely reversible clinical symptoms and remission of imaging abnormalities. [ABSTRACT FROM AUTHOR]

Key Clinical Message A novel radiologic sign in patients with renal failure and uremic encephalopathy (UE) with metabolic acidosis has recently been identified as the lentiform fork sign. On magnetic resonance imaging (MRI), the “lentiform fork sign” has been described as bilateral symmetrical hyperintensities in the basal ganglia encircled by a hyperintese rim delineating the lentiform nucleus. Changes in uremic solute retention, aberrant blood–brain barrier transport, disordered vascular reactivity, altered electrolyte and acid–base balance, and altered hormone metabolism are the most likely causes of the condition. A 56‐year‐old male with end‐stage renal disease was brought to the emergency room for a progressive change in mental status and involuntary arm movements over the previous 5 days, which were accompanied by mild dyspnea. A brain MRI was performed, and it revealed hyperintensity on T2/FLAIR in the white matter surrounding the basal ganglia. the patient was treated with dialysis and improved greatly. Intensified hemodialysis and glycemic control are the cornerstones of treating diabetic uremic syndrome (DUS) with likely reversible clinical symptoms and remission of imaging abnormalities.

Diabetic uremic syndrome has been rarely reported in patients on maintenance dialysis for diabetic nephropathy who present subacutely with neurological symptoms and bilateral basal ganglia lesions. There are also a few reports on metformin-induced encephalopathy, which is clinically similar to diabetic uremic syndrome. Because some patients with each of these diseases also have metabolic acidosis, it is speculated that these two diseases may have the same pathology. Recently, the term “extrapyramidal syndromes of chronic kidney disease and dialysis” (EPS-CKDD), with associated diagnostic criteria, has been proposed to describe these conditions, and metformin use is considered a risk factor for developing these syndromes. We report a case of a patient on maintenance hemodialysis for diabetic nephropathy who was taking metformin and developed subacute parkinsonism and bilateral basal ganglia lesions that rapidly improved after discontinuation of metformin with continued maintenance hemodialysis. We should ascertain whether patients with EPS-CKDD are taking metformin because it may be inappropriately prescribed for end-stage renal disease. If metformin has been prescribed, it should be discontinued immediately; its discontinuation may lead to rapid symptom recovery and improved prognosis.

Basal ganglia lesions showing an expansile high signal intensity on T2-weighted MRI are termed the lentiform fork sign. This specific finding is mainly observed in diabetic patients with uremic encephalopathy with metabolic acidosis, although there are also reports in patients with ketoacidosis, dialysis disequilibrium syndrome, intoxication, and following drug treatment (e.g., metformin). A 57-year-old Japanese man on chronic hemodialysis for 4 years because of diabetic nephropathy was admitted to our hospital for relatively rapid-onset gait disturbance, severe dysarthria, and consciousness disturbance. Brain T2-weighted MRI showed the lentiform fork sign. Hemodialysis was performed the day before admission, and laboratory tests showed mild metabolic (lactic) acidosis, but no uremia. Surprisingly, metformin, which is contraindicated for patients with end-stage kidney disease, had been prescribed for 6 months in his medication record, and his sluggish speaking and dysarthria appeared gradually after metformin treatment was started. Thus, the encephalopathy was considered to be related to metformin treatment. He received hemodialysis treatment for 6 consecutive days, and his consciousness disturbance and dysarthria improved in 1 week. At the 8-month follow-up, the size of the hyperintensity area on MRI had decreased, while the mild gait disturbance remained. Considering the rapid onset of gait and consciousness disturbance immediately before admission, diabetic uremic syndrome may also have occurred with metformin-related encephalopathy, and resulted in the lentiform fork sign, despite the patient showing no evidence of severe uremia on laboratory data.

Basal ganglia lesions showing an expansile high signal intensity on T2-weighted MRI are termed the lentiform fork sign. This specific finding is mainly observed in diabetic patients with uremic encephalopathy with metabolic acidosis, although there are also reports in patients with ketoacidosis, dialysis disequilibrium syndrome, intoxication, and following drug treatment (e.g., metformin). A 57-year-old Japanese man on chronic hemodialysis for 4 years because of diabetic nephropathy was admitted to our hospital for relatively rapid-onset gait disturbance, severe dysarthria, and consciousness disturbance. Brain T2-weighted MRI showed the lentiform fork sign. Hemodialysis was performed the day before admission, and laboratory tests showed mild metabolic (lactic) acidosis, but no uremia. Surprisingly, metformin, which is contraindicated for patients with end-stage kidney disease, had been prescribed for 6 months in his medication record, and his sluggish speaking and dysarthria appeared gradually after metformin treatment was started. Thus, the encephalopathy was considered to be related to metformin treatment. He received hemodialysis treatment for 6 consecutive days, and his consciousness disturbance and dysarthria improved in 1 week. At the 8-month follow-up, the size of the hyperintensity area on MRI had decreased, while the mild gait disturbance remained. Considering the rapid onset of gait and consciousness disturbance immediately before admission, diabetic uremic syndrome may also have occurred with metformin-related encephalopathy, and resulted in the lentiform fork sign, despite the patient showing no evidence of severe uremia on laboratory data.

Basal ganglia lesions showing an expansile high signal intensity on T2-weighted MRI are termed the lentiform fork sign. This specific finding is mainly observed in diabetic patients with uremic encephalopathy with metabolic acidosis, although there are also reports in patients with ketoacidosis, dialysis disequilibrium syndrome, intoxication, and following drug treatment (e.g., metformin). A 57-year-old Japanese man on chronic hemodialysis for four years because of diabetic nephropathy was admitted to our hospital for relatively rapid-onset gait disturbance, severe dysarthria, and consciousness disturbance. Brain T2-weighted MRI showed the lentiform fork sign. Hemodialysis was performed the day before admission, and laboratory tests showed mild metabolic (lactic) acidosis, but no uremia. Surprisingly, metformin, which is contraindicated for patients with end-stage kidney disease, had been prescribed for six months in his medication record, and his sluggish speaking and dysarthria appeared gradually after metformin treatment was started. Thus, the encephalopathy was considered to be related to metformin treatment. He received hemodialysis treatment for six consecutive days, and his consciousness disturbance and dysarthria improved in one week. At the eight-month follow-up, the size of the hyperintensity area on MRI had decreased, while the mild gait disturbance remained. Considering the rapid onset of gait and consciousness disturbance immediately before admission, diabetic uremic syndrome may also have occurred with metformin-related encephalopathy, and resulted in the lentiform fork sign, despite the patient showing no evidence of severe uremia on laboratory data.

Here, we describe the case of a 47-year-old man with bilateral striatal lesions with diabetic uremia. Following 4 years of hemodialysis, the patient experienced sudden onset of rigidity, bradykinesia, gait disorder, and postural instability. Symptoms were remediated 2 months later, and were no longer responsive to levodopa approximately 1 year after the onset. Brain magnetic resonance imaging (MRI) during the acute phase showed T 2-weighted high signal edematous lesions in the bilateral striatum, subsequently developing into vacuolated lesions. A positron emission tomography (PET) scan using ((11)C)-labeled 2-carbomethoxy-3-(4-fluorophenyl) tropane [((11)C) CFT] and ((11)C)-labeled raclopride [((11)C) RAC] revealed significant decreases bilaterally in pre- and postsynaptic functions of the dopaminergic neurons. When we experience a case with bilateral putaminal destruction resulting in Parkinsonism, examination of the function of doperminergic neurons and dopamine receptors using molecular imaging is useful to predict levodopa response and prognosis. [ABSTRACT FROM AUTHOR]