Acute hyperammonemic encephalopathy in adults: imaging findings

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Acute hyperammonemic encephalopathy (AHE) is a critical condition with high morbidity and mortality if not treated promptly.
• The characteristic MR imaging findings of AHE in adult patients are not widely recognized.
• Early identification of AHE is essential for timely intervention and improved patient outcomes.

Purpose of the Study:

• To describe the MR imaging findings associated with acute hyperammonemic encephalopathy in adult patients.
• To highlight specific imaging patterns that can aid in the diagnosis of AHE.
• To increase awareness among radiologists regarding the MR imaging features of AHE.

Main Methods:

• Retrospective review of clinical data, MR imaging, and outcomes of consecutive patients with documented hyperammonemic encephalopathy.
• All patients underwent cranial MR imaging at 1.5T.
• Analysis of imaging findings, including signal abnormalities and diffusion characteristics.

Main Results:

• Four adult patients (2 women, mean age 42 years) with hyperammonemic encephalopathy were included.
• All patients exhibited bilateral, symmetric signal-intensity abnormalities in the insular cortex and cingulate gyrus, often with restricted diffusion.
• Additional cortical involvement was variable and asymmetric; subcortical white matter, basal ganglia, thalami, and midbrain involvement were less common.

Conclusions:

• Symmetric involvement of the cingulate gyrus and insular cortex on MR imaging is a key finding in acute hyperammonemic encephalopathy.
• These distinctive imaging features should prompt consideration of AHE in the differential diagnosis.
• Radiologists recognizing these patterns can facilitate earlier diagnosis and management of AHE.