Prominent myelin vacuolization in neurofibromatosis type 2.

Myelin vacuolization has previously been documented by MRI with histopathologic correlation in patients with neurofibromatosis type 1. This paper presents a patient with neurofibromatosis type 2 with MRI findings consistent with a prominent form of myelin vacuolization, unilaterally involving the right thalamus, globus pallidus and substantia nigra. On MRI, they appeared as multiple nodular-ovoid structures with a layered configuration. They were hypointense on T1-weighted, and FLAIR images, and hyperintense on T2-weighted images. On the apparent diffusion coefficient (ADC) map of an echo-planar diffusion imaging sequence, their ADC value ranged between 1.98 and 2.27x10(-3) mm(2)/s, a value higher than that of normal cerebral parenchyma, less than that of CSF.