An Irreversible Radiological Finding of Lentiform Fork Sign in a Patient With Uremic Encephalopathy: A Case Report

Basal ganglia are highly metabolically active deep gray matter structures that are commonly affected by toxins, metabolic abnormalities, and systemic, degenerative, and vascular conditions. Basal ganglion affected by uremic encephalopathy can typically result in a "Lentiform fork sign" on T2-weighted imaging (T2WI) and a fluid-attenuated inversion recovery (FLAIR) sequence of magnetic resonance imaging (MRI). This sign represents bilateral symmetrical hyperintensities in the basal ganglia surrounded by a characteristic hyperintense rim demarcating the lentiform nucleus from surrounding structures. This finding is also reported in other conditions resulting in metabolic acidosis from any cause, e.g., diabetic ketoacidosis, organic acidemias, dialysis disequilibrium syndrome, and drugs like metformin. In an appropriate clinicopathological context, the presence of this sign helps in the accurate diagnosis of uremic encephalopathy. The peculiarity lies in the reversible nature of these lesions and their affective response to treatment. However, sometimes these lesions may not be reversible. We present the case of a 60-year-old female who presented to the ER with chief complaints of fever and altered sensorium. Laboratory workup revealed deranged renal function tests (RFTs) and leukocytosis with pyuria. MRI of the brain showed bilateral basal ganglion hyperintensities on T2WI/FLAIR images characteristic of the lentiform fork sign. Therefore, a diagnosis of uremic encephalopathy due to acute kidney injury (AKI) secondary to septic shock from urosepsis was made. The patient was managed conservatively with IV hydration and antibiotics. Remarkable clinical recovery was seen over three weeks. The patient was stable on a five-month follow-up. However, the repeat MRI did not show resolution of the lesions.