Pulsed high‐dose dexamethasone is not effective in patients with multifocal motor neuropathy

The hypothesis that multifocal motor neuropathy (MMN) is an immune mediated neuropathy has led to the trial of several immunological treatments. ’ Prednisolone and plasma exchange were ineffective in most patients with MMN. Among the immunosuppressants, only cyclophosphamide given at high doses intravenously followed by maintenance treatment with oral cyclophosphamide treatment seems to be consistently This treatment may have considerable side effects and may be unsuitable for the less severely affected patients. More recently, investigators have found high dose intravenous immunoglobulin (IvIg) treatment to be effective in most patients with MMN,1,4 although in many cases frequent IvIg infusions were necessary to maintain the effect of treatment.6 In some patients MMN progressed during IvIg maintenance the rap^. ^ The use of IvIg treatment in MMN may be limited by its costs due to the frequency of infusions. We tested the efficacy of pulsed, high-dose dexamethasone (40 mg/d for four consecutive days every 28 days, given in six cycles) based on the consideration that pulsed, high-dose dexamethasone therapy 1) may be effective in idiopathic thrombocytopenic purpura (ITP) which is, like MMN, a disease known to respond well to IvIg treatment;’ 2) may reduce immunoglobulin production in clonal B-cell disorders, even those refractory to other cytotoxic agents;7 3) is usually well-tolerated; and 4) is far less expensive than IvIg. ’ Case reports. Two men (27 and 28 years old) were evaluated for progressive, asymmetric weakness of arms and legs that had developed over a period of 2 and 4 years. Sensation was intact. Tendon reflexes were low or absent in affected limbs. Muscle strength measurements by hand-hand myometry4 showed in Patient l weakness of right abductors of the upper arm (220 Newton (N)), left wrist flexors (170 N) and extensors (175 N), and left foot flexors (40 N); in Patient 2 weakness of the left wrist flexors (110 N) and extensors (105 N), right hip flexors (210 N), knee flexors (180 N) and foot flexors (130 N). Muscle strength in other muscle groups was normal. CSF protein was mildly elevated in both patients (5.6 mg/dL in both patients). Electrodiagnostic studies were done extensively as described previ~usly. ~ Motor conduction blocks (outside the sites of nerve compression) were found in Patient 1, in the right ulnar and tibia1 nerves; in Patient 2 in the left median and ulnar nerves. On the basis of the clinical presentation and electrodiagnostic studies, a diagnosis of MMN was made. Treatment. In both patients muscle strength improved after IVIg treatment (0.4 g k g for 5 days). In Patient 1, muscle strength improved in the left foot flexors from 40 to 110 N and to normal strength in the other affected muscle groups; in Patient 2, all muscle groups returned to normal strength. However, the effect of IVIg treatment lasted only 8 weeks in both patients. After IVIg was no longer effective and muscle strength had returned to pretreatment levels, both patients were treated with pulsed, highdose dexamethasone (40 mg/d for 4 days every 28 days, given in six cycles). Muscle strength was measured before and 1 week after onset of treatment, and after that once every 2 weeks using a hand-held dynamometer. After 6 months muscle strength had deteriorated in both patients with at least 40 N in all affected muscle groups. Patient 2 was not able to walk up the stairs without support. Weakness was most severe 1 week after medication had been taken. Both patients described severe sensations of “pain in nerves,” sleeping disturbances, and dysphoria. Both patients refused further dexamethasone treatment after six cycles and improved again after another course of IVIg treatment. Discussion. We studied whether pulsed, high-dose dexamethasone was effective in patients with MMN who previously had responded well to IVIg treatment. A beneficial effect of this treatment was anticipated considering a potential immunosuppressive effect of pulsed, high-dose dexamethasone treatment and the response of immunosuppressive therapy in MMN,3,7 but both patients deteriorated during dexamethasone treatment. A steroidinduced deterioration was described previously in patients with MMN after daily treatment with prednisolone.l,z We cannot recommend pulsed, high-dose dexamethasone for patients with MMN.