Hyperintense and hypointense MRI signals of the precentral gyrus and corticospinal tract in ALS: A follow-up examination including FLAIR images
Introduction
Magnetic resonance imaging (MRI) of the brain is currently performed in patients with suspected amyotrophic lateral sclerosis (ALS) to exclude conditions resembling ALS. Recently, some reports focused on MRI signal changes in confirmed ALS patients. T2-weighted MR images of the brain have shown hyperintense alterations of the corticospinal tract [1], [2], [3], [4], [5], [6], [7]. In fluid attenuated inversion recovery (FLAIR) images, hyperintense changes in the subcortical white matter of the precentral gyrus were seen even more often than in T2-weighted images [8]. In our recent study in 31 ALS patients, hyperintense alterations along the corticospinal tract were revealed by FLAIR images significantly more often than by T2-, T1- and proton density-weighted images [9]. There is some overlap with findings in healthy controls [8], [9]. However, the quantified FLAIR signal (contrast to noise ratio, CNR) at the subcortical precentral gyrus was significantly higher in the ALS patients than in the healthy controls [9].
In addition to the hyperintense white matter changes, hypointense signals at the margin of the precentral gyrus (“low signal rim”) has been found in some ALS patients in T2-weighted [2], [4], [8], [9], [10], [11] and, recently, also in FLAIR images [8], [9]. To further investigate hyperintense signals of the corticospinal tract and hypointense signals of the precentral gyrus in ALS, we repeated MR imaging of the head at least 1 year after the first examination.
Section snippets
Patients
Seventeen ALS patients were included in the follow-up study (12 men, 5 women, age 29–67 years, mean age 53.29±9.53 years, 6 bulbar, 11 spinal onset). This group was a subgroup of the 31 patients studied previously [9]. The diminished number of reexamined patients compared to the first examination was caused by the death of 4 patients, 6 patients refused the reexamination and 4 patients were lost to follow-up. The time from the onset of the disease to the first examination was 15.35±10.30 months
Visual evaluation
In some patients, there was a slight increase of the hyperintense signals along the corticospinal tract, especially at the subcortical precentral gyrus (Fig. 2A,B) and at the pons (Fig. 2C,D) in FLAIR images. However, the visual evaluation of the total group showed no significant change (p>0.05) at the precentral subcortical gyrus or any other part of the corticospinal tract (Table 1). The sum score of all five evaluated levels changed slightly from 10.12±1.83 (mean±S.D.) to 10.30±2.23 in FLAIR
Discussion
Amyotrophic lateral sclerosis is characterized by the degeneration of lower and upper motor neurons. Affliction of the lower motor neurons is easily determined by electrodiagnostic methods. Assessment of upper motor neuron degeneration is often limited in the clinical as well as in the electrodiagnostic examination. Additional information may be gained by MR imaging of the brain. In few ALS patients, hyperintense alterations of the corticospinal tract have been seen in proton density-weighted
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2020, Journal of the American College of RadiologyCitation Excerpt :Contrast is typically not needed for the evaluation of suspected motor neuron disease, but it may be helpful in excluding other infectious, inflammatory, or neoplastic differential considerations. The most common MRI finding in the brain in ALS is abnormal signal on T2/FLAIR or proton density–weighted images, which can be seen anywhere within the corticospinal tracts from the subcortical white matter to the pons (though it is most frequently seen in the posterior limb of the internal capsule and the cerebral peduncles), which likely corresponds to the underlying demyelination, axonal degeneration, and gliosis seen on histopathology [77-81]. T2∗-weighted imaging or susceptibility-weighted imaging is also important in the evaluation of suspected ALS because abnormal hypointensity in the precentral gyrus and gray matter has been noted to be highly sensitive and specific for ALS [82-85].
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2015, Magnetic Resonance ImagingCitation Excerpt :In particular, in ALS the neuroimaging approach evaluates the UMN dysfunction and can be divided into two main lines of research. The first one investigates UMN impairment at the cortical level and includes conventional morphological studies [174,175], quantitative measurement of atrophy by means of voxel-based morphometry (VBM) [176,177] or cortical thickness measurement through surface-based morphometry [178]. Moreover, functional MRI [179–181] and magnetization transfer imaging [182] have been employed in order to explore the motor function/reorganization and tissue alterations at a cortical level, respectively.