Case Report: A Case of Encephalopathy Presenting the Lentiform Fork Sign on MRI in a Diabetic Dialysis Patient

Yuji Sato,Shouichi Fujimoto,Ryuzoh Nishizono,Hiroko Inagaki,Yuri Ishizaki,Masao Kikuchi

doi:10.12688/f1000research.25597.2

Yuji Sato, Shouichi Fujimoto + Show 4 more

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https://doi.org/10.12688/f1000research.25597.2

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Abstract

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.

Highlights

Basal ganglia lesions showing an expansile high signal intensity on T2weighted MRI are termed the lentiform fork sign
Any further responses from the reviewers can be found at the end of the article Introduction Metabolic encephalopathy with abnormal basal ganglia lesions has been reported in hemodialysis patients
In addition to diabetic uremic syndrome (DUS)[4,5], the lentiform fork sign can be observed in severe metabolic acidosis[11–13], dialysis disequilibrium syndrome[14], and metforminassociated encephalopathy (ME)[6,7]

Summary

11 Aug 2020 report

Any reports and responses or comments on the article can be found at the end of the article. Case report A 57-year-old Japanese man who had been on maintenance hemodialysis three-times weekly for four years because of diabetic nephropathy developed gait and consciousness disturbance (the Glasgow Coma Scale score of E3V4M6), fatigue, numbness in his left upper limb, and a slow response during conversation approximately 10 days before admission His wife denied him taking mushrooms or star fruit, which can cause consciousness disturbance in hemodialysis patients. Brain MRI showed bilateral symmetrical basal ganglia lesions with an expansile high signal intensity (lentiform fork sign) on T2-weighted sequences (Figure 1b), which was not seen on MRI taken one-year prior when he developed a right thalamic lacunar infarction In his medication history, he had taken metformin for six months. Brain lesions were still evident on CT scan (Figure 1e)

Discussion

Case Report