Magnetic evoked field (MEF) analysis can detect subclinical abnormalities in sensory pathways, with the potential of explaining some of the neurological deficits associated with Wilson disease, according to a recently published study in the journal Neurology India.

Although Wilson disease can produce a vast array of neurological manifestations ranging from parkinsonism to psychosis, sensory symptoms are rare. Some electrophysiological studies have detected anomalies in evoked responses to sensory stimuli, the researchers noted.

MEFs have been successfully used for brain mapping in neurological conditions such as Parkinson’s disease and Alzheimer’s disease, the study team noted. Therefore, the authors aimed to use MEF to detect subclinical abnormalities that could potentially contribute to understanding the Wilson disease process.

Read about Wilson disease diagnosis

The study included 49 persons, 28 patients with Wilson disease and 21 healthy controls. Medical history and demographic data of each patient were obtained and recorded, and the severity of Wilson disease in each case was assessed using standardized clinical tools such as the Neurological symptom score. A control brain magnetic resonance imaging (MRI) was performed in all cases.

Clinical manifestations in the patients with Wilson disease were varied. MRI signal abnormalities were most common in the midbrain, the putamen, the pons, and the thalamus.

MEF analysis revealed significant discrepancies in source location between control patients and patients with Wilson disease in the visual evoked field (VEF) and auditory evoked field (AEF) studies. 

In the AEF of patients, M100 had shorter latency than in controls, while the VEF of patients had longer M75 and M100 latencies than controls. Examination of somatosensory evoked fields (SSEF) revealed that patients and controls had a significant difference in M20-latency to the right median nerve stimulation.

Correlation between findings and disease severity revealed that only M20-latency in SSEF to left median nerve stimulation had any correlation with disease severity.

“The study unravels subclinical functional alterations in WD, which might explain some of the clinical deficits,” the authors concluded.

Reference

Sinha S, Aruna R, Mariyappa N, et al. Insights from magnetic evoked field analysis in patients with Wilson’s disease. Neurol India. Published online November 21, 2022. doi:10.4103/0028-3886.359230