Author response: Meta-analysis of magnetic resonance spectroscopy in the diagnosis of hepatic encephalopathy

The authors thank Dr. Gupta for the comment on our article.¹ Hepatic encephalopathy (HE) is associated with significant morbidity and mortality in cirrhosis; its pathophysiology is incompletely understood. Our meta-analysis was a review of magnetic resonance spectroscopy (MRS) data in HE, which confirmed a specific metabolic pattern, consisting of increased glutamine/glutamate—with reduced choline—and myo-inositol, particularly in the parietal lobes.¹ The changes increased with the severity of HE. We agree that this would have limited diagnostic utility in overt HE, which is clinically obvious. We strongly disagree, however, about covert or minimal HE (MHE), which are defined as the presence of neuropsychologic or neurophysiologic abnormalities in patients with no obvious—i.e., at least disorientation for time or asterixis—clinical signs of overt HE. Here, there is a potential role for MRS in diagnosis, monitoring, and investigation. In a recent French cohort of cirrhotic individuals with and without MHE, HE pattern MRS changes in the pallidum were present in 95% of MHE vs 0% of unimpaired patients (p < 0.001), suggesting MRS could outperform other modalities of MHE diagnosis.² MRS may also have a significant role in future pathophysiologic and pharmacologic HE studies.