PMC4322379_01
Case 1. 42-year-old male with bilateral hypertrophic olivary degeneration following excision of a fourth ventricular epidermoid cyst Axial. T2-weighted images through fourth ventricle (a and b) show postoperative gliosis (white arrows).
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F1
MR examination revealed postoperative changes in the posterior fossa with evidence of gliosis around 4th ventricle [Figure 1].
Case 1. 42-year-old male with bilateral hypertrophic olivary degeneration following excision of a fourth ventricular epidermoid cyst Axial. T2-weighted images (a and b) through medulla show bilateral hyperintensities in olivary region with mild hypertrophy (white arrows).
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F2
MRI also revealed focal, bilateral, symmetric, ill-defined, T2-hyperintensities involving the olivary region of the medulla with mild hypertrophy [Figure 2].
42-year-old male with bilateral hypertrophic olivary degeneration following excision of a fourth ventricular epidermoid cyst. Video clip shows palatal myoclunus.
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F3
A second MR examination of the brain done 19 months following surgery showed a reduction in the hypertrophy and hyperintensity of the olivary region [Figure 3].
PMC4322379_02
Case 1. 42-year-old male with bilateral hypertrophic olivary degeneration following excision of a fourth ventricular epidermoid cyst. Axial T2-weighted image 14 months later through same level as 2(b) shows reduction in hypertrophy and hyperintensity.
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F4
MR examination revealed HOD as a small, ill-defined, nonenhancing T2-hyperintensity involving the olivary region of the medulla on the right side with mild hypertrophy [Figures 4 and 5b].
Case 2. 49-year-old male with unilateral HOD following brainstem hemorrhage. (a) and (b) T2-weighted axial images through medulla show ill-defined hyperintensities in olivary region on right side with mild hypertrophy (white arrows).
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F5
MR examination revealed HOD as a small, ill-defined, nonenhancing T2-hyperintensity involving the olivary region of the medulla on the right side with mild hypertrophy [Figures 4 and 5b]. Features of the primary lesion were also seen as chronic hemorrhage involving the pons, midbrain [Figure 5], dorsal aspect of the right lentiform nucleus and the adjacent posterior limb of the internal capsule.