Elsevier

NeuroToxicology

Volume 24, Issue 6, December 2003, Pages 835-838
NeuroToxicology

Calcification Mimicking Manganese-Induced Increased Signal Intensities in T1-Weighted MR Images in a Patient Taking Herbal Medicine: Case Report

https://doi.org/10.1016/S0161-813X(03)00060-3Get rights and content

Abstract

Characteristic high signal intensities confined to the globus pallidus on T1-weighted magnetic resonance image (MRI) can be observed in manganese (Mn)-exposed workers, however, these high signals should be differentiated from those due to other causes such as fat, hemoglobin breakdown products, melanoma, neurofibromatosis, and calcification. A 39-year-old woman was admitted with mutism and involuntary movements which had developed the day before. She had ingested two packs of liquid herbal medicine containing 0.53 mg of Mn daily for 4 months prior to visiting our hospital. Her MRI showed high signals, confined mainly to the globus pallidus on T1-weighted images. Follow-up brain MRI at an interval of 11 months showed no interval change. Brain computed tomography (CT) at the time of the second MRI showed symmetric calcification on both globus pallidus. Blood levels of liver function tests, calcium, phosphorus, and parathyroid hormone were within normal ranges. The increased signals, which were first presumed to be induced by Mn, were concluded to be due to calcification based on the following reasons. First, follow-up brain MRI at an interval of 11 months did not show any interval change. Second, the ingested amount of 1.06 mg Mn daily for 4 months is even less than that added to mineral supplements for adults. Third, Mn-induced high signals in T1-weighted MRI do not show any abnormal findings in brain CT. The present case report suggests that brain CT should be performed to rule out symmetric calcification on basal ganglia in patients showing increased signals in T1-weighted MRI, but who do not have a significant exposure history to Mn. The present report also showed that the amount of 1.06 mg Mn daily ingested for 4 months did not cause the high signal in brain MRI.

Section snippets

INTRODUCTION

The manganese ion (Mn2+) has five unpaired electrons in the 3d orbit, which results in its large magnetic moment, causing the shortening of T1-relaxation time and an increase in signal intensity on T1-weighted magnetic resonance images (MRI). Because of the paramagnetic quality of Mn, a bilateral symmetrical increase in signal intensities, confined to the globus pallidus and midbrain, can be observed on T1-weighted MRI, but with no alteration on the T2-weighted image. Characteristic high signal

CASE REPORT

A 39-year-old woman was admitted with mutism and involuntary movements which had developed the day before. She was alert and cooperative, but could not speak. Her eyes were blinking, and her head was nodding at an interval of 10–30 s. Neurologic examination showed no focal neurologic deficits. She began to speak the next day, but she could not recall what she had done 2 days before. Laboratory tests such as glucose, urea nitrogen, calcium, liver function tests, and complete blood cell counts

DISCUSSION

The increased signals in T1-weighted MRI without corresponding alterations on the T2-weighted image, which were first presumed to be induced by Mn, were concluded to be due to calcification based on the following reasons.

First, follow-up brain MRI at an interval of 11 months did not show any interval change. The Mn-induced high signals in MRI usually disappear within 6 months or 1 year following the withdrawal from the source of Mn accumulation (Newland et al., 1989, Nelson et al., 1993, Huang

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