PMC9087846_01
Sequential transverse MR images from case 1. (A-E), diffusion-weighted (DWI); (F-J), T2-weighted (T2W): Diffuse bilaterally symmetrical hyperintensity involving white matter tracts is present on DWI and T2W images. Hyperintensity consistent with the descending corticospinal tract (white arrows) is present at the level of the internal capsule (A,F), midbrain crus (B,G), pyramidal tracts (C,H), pyramidal decussation (D,I), and lateral corticospinal tracts (E,J). Additional white matter tracts are defined, including corona radiata [(A,F), white arrowheads] and hippocampal fornix [(A), black arrowhead].
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F1
MRI of the brain revealed extensive hyperintensity of cerebral and brainstem white matter on T2-weighted (T2W) and T2W fluid attenuated inversion recovery (FLAIR) sequences, with no contrast enhancement (Figures 1, 2). T2W hyperintense white matter structures also appeared hyperintense on diffusion-weighted imaging (DWI) (Figures 1, 2) and hypointense on the apparent diffusion coefficient (ADC) map (Figure 2), consistent with restricted diffusion.
(A-C) MR images at the level of the thalamus from case 1 demonstrating restricted diffusion of defined lesions. Hyperintensity of corona radiata (white arrowheads) on T2W (A) and diffusion-weighted imaging (DWI) (B) images with hypointensity on the corresponding apparent diffusion coefficient map (C) is consistent with restricted diffusion. Parasagittal (D) and midsagittal T2W images (E) highlight the descending [(D), white arrowhead] and pyramidal components [(E), white arrow] of the corticospinal tract. The olfactory tract [(D), white arrow], rostral commissure [(F), white arrow, transverse T2W image], and columns of the fornix [(F), white arrowhead] ventral to the hyperintense corpus callosum are also clearly defined.
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F2
MRI of the brain revealed extensive hyperintensity of cerebral and brainstem white matter on T2-weighted (T2W) and T2W fluid attenuated inversion recovery (FLAIR) sequences, with no contrast enhancement (Figures 1, 2). T2W hyperintense white matter structures also appeared hyperintense on diffusion-weighted imaging (DWI) (Figures 1, 2) and hypointense on the apparent diffusion coefficient (ADC) map (Figure 2), consistent with restricted diffusion.
PMC9087846_02
MR images from cases 2 (A,B) and 3 (C-L) demonstrating similar hallmark corticospinal tract lesions in both cases and demonstrating resolution of MRI changes in case 3. Transverse T2W images at the level of the midbrain and medulla oblongata for cases 2 (A,B) and 3 (C,D) demonstrate hyperintensity of corona radiata (white arrowheads) and prominence of the corticospinal tracts (white arrows) within the brainstem as in case 1. Lesions are again most noticeable on diffusion-weighted imaging (DWI) images from case 3 [(E,F), white arrows]. Case 3 initial transverse T2W (G), DWI (I) and apparent diffusion coefficient (ADC) map (K) images at the level of the caudate nuclei confirm restricted diffusion within white matter tracts as in case 1. Reversal of imaging abnormalities on repeated T2W (H), DWI (J), and ADC map (L) 6 months later was consistent with resolution of clinical signs.
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F3
ADC maps (Figure 3). Abnormalities were most prominent in the CST, corona radiata, internal capsule, and corpus callosum. PO daily) for cerebral inflammation, maropitant (2 mg/kg PO daily) as an antiemetic and omeprazole (20 mg total PO q12 h) to reduce the risk of gastrointestinal ulceration, the dog returned to normal within 18 days of the initial onset of signs. Prednisone dose was tapered over 2 weeks, and the dog was neurologically normal with normal MRI 6 months later (Figure 3).
PMC9087846_03
MR images from cases 2 (A,B) and 3 (C-L) demonstrating similar hallmark corticospinal tract lesions in both cases and demonstrating resolution of MRI changes in case 3. Transverse T2W images at the level of the midbrain and medulla oblongata for cases 2 (A,B) and 3 (C,D) demonstrate hyperintensity of corona radiata (white arrowheads) and prominence of the corticospinal tracts (white arrows) within the brainstem as in case 1. Lesions are again most noticeable on diffusion-weighted imaging (DWI) images from case 3 [(E,F), white arrows]. Case 3 initial transverse T2W (G), DWI (I) and apparent diffusion coefficient (ADC) map (K) images at the level of the caudate nuclei confirm restricted diffusion within white matter tracts as in case 1. Reversal of imaging abnormalities on repeated T2W (H), DWI (J), and ADC map (L) 6 months later was consistent with resolution of clinical signs.
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F3
ADC maps (Figure 3). Abnormalities were most prominent in the CST, corona radiata, internal capsule, and corpus callosum. PO daily) for cerebral inflammation, maropitant (2 mg/kg PO daily) as an antiemetic and omeprazole (20 mg total PO q12 h) to reduce the risk of gastrointestinal ulceration, the dog returned to normal within 18 days of the initial onset of signs. Prednisone dose was tapered over 2 weeks, and the dog was neurologically normal with normal MRI 6 months later (Figure 3).