Teaching NeuroImages: Acute neurologic deficits due to Baló concentric sclerosis

A previously healthy 40-year-old man developed acute left-sided weakness and numbness that progressed over 2 weeks. Physical examination revealed decreased sensation to pinprick in the left arm and leg and left leg weakness. MRI supported a diagnosis of Balo concentric sclerosis (BCS), a rare demyelinating disease (figure). The concentric bands of differing intensities on MRI are due to alternating layers of normal and demyelinated tissue that is classically observed with BCS.1,2 Patients with BCS commonly present with acute neurologic symptoms, which can be due to a solitary lesion. The clinical course can be fulminant and progressive or benign. In the case presented, the patient's symptoms improved within 1 week of starting high-dose glucocorticoids.