Case Report: A case of encephalopathy presenting the lentiform fork sign on MRI in a diabetic dialysis patient - diabetic uremic syndrome or metformin-related encephalopathy?

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

doi:10.12688/f1000research.25597.1

Yuri Ishizaki, Shouichi Fujimoto + Show 4 more

Open Access

https://doi.org/10.12688/f1000research.25597.1

Copy DOI

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 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.

Highlights

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 acidosis11–13, dialysis disequilibrium syndrome14, and metforminassociated encephalopathy (ME)6,7
Discussion we report a diabetic hemodialysis patient with consciousness disturbance who presented with the lentiform fork sign on T2-weighted brain MRI

Summary

Introduction

Metabolic encephalopathy with abnormal basal ganglia lesions has been reported in hemodialysis patients. 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, 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