This patient should receive intravenous methylprednisolone. Her symptoms are consistent with a new multiple sclerosis (MS) relapse, most likely localizing to a new lesion in the pons and pontocerebellar pathways on the right. The standard of care for MS relapses is a high-dose glucocorticoid, usually intravenous methylprednisolone, 1 g/d for 3 to 5 days. Although this treatment has not been shown to reduce the amount of long-term disability sustained in a relapse, it substantially hastens the rate of recovery. Because of the unclear long-term benefit and the potential for adverse effects, acute high-dose glucocorticoid therapy is usually reserved for attacks resulting in sustained impairment in functional status that interferes substantially with activities of daily living.

In addition to treatment of individual relapses, most patients with relapsing-remitting MS receive chronic maintenance therapy with immunomodulatory or immunosuppressive medications, such as the interferon beta-1a that this patient takes. These disease-modifying therapies have been shown to reduce the relapse rate, slow disability progression, and reduce the accumulation of new demyelinating lesions on MRI. Glatiramer acetate is another disease-modifying drug that has been shown to reduce the relapse rate by approximately one third compared with placebo and appears equivalent to the interferon beta preparations in head-to-head studies. Combining glatiramer acetate with an interferon beta provides no added benefit compared with what either drug achieves alone. Additionally, disease-modifying medications are not effective in hastening recovery in a patient with a functionally significant acute exacerbation of MS.

Although an increasing number of studies suggest the equivalency of oral treatment with prednisone and intravenous treatment with another glucocorticoid for MS, the reported equivalent dose of prednisone is 1250 mg/d, which is a very high dose. In the original Optic Neuritis Treatment Study, which compared treatment of optic neuritis with oral prednisone (1 mg/kg), intravenous methylprednisolone (1 g/d), or placebo, the oral prednisone group had worse outcomes after treatment than even the placebo group. Thus, oral prednisone in the range of 1 mg/kg may actually be detrimental in treating acute demyelination.

Relapses that are refractory to glucocorticoid treatment may respond to rescue therapy with plasmapheresis. Since this patient has not received a trial of intravenous methylprednisone, treatment with plasmapheresis is premature.