Maintenance IVIg therapy in myasthenia gravis does not affect disease activity

There is insufficient data on the efficacy of intravenous immunoglobulins (IVIg) as maintenance treatment in myasthenia gravis (MG). We therefore examined response to maintenance IVIg therapy in a cohort of MG patients.

We reviewed all MG patient files treated with IVIg in our neuro-immunology clinic from 1/1995 to 9/2012. Patients treated with maintenance IVIg for a minimum of one year were separately analyzed. Disease severity was evaluated according to the Myasthenia Gravis Foundation of America clinical classification.

IVIg was considered for maintenance therapy in 52 MG patients who had not responded to pyridostigmine, prednisone, azathioprine or combinations of these drugs. Fifteen patients did not improve with initial IVIg while thirty seven patients had a beneficial response and were treated with maintenance IVIg for an average of 5.9 years (range 1-17 years). Twenty two (59%) patients were female with an average age onset of disease 44.8 years. Thirty three were seropositive for acetylcholine receptor antibody and 13 had previous thymectomy. Twenty three and 14 patients achieved mild or moderate improvement respectively in disease activity while on IVIg therapy but none achieved full remission. Beneficial response was associated with older age, bulbar presentation, seropositivity and a higher antibody titer and less with ocular presentation. IVIg enabled reduction of other treatments including pyridostigmine, prednisone and azathioprine.

In this retrospective study on a relative small cohort of MG patients maintenance IVIg therapy was successful in reducing symptoms of MG but seems to be ineffective in inducing full remission or reducing disease activity. IVIg should be regarded only as symptomatic therapy in MG.