Clinical Reasoning: A 34-year-old man with recurrent limb weakness

Human immune globulin infusion in the management of multifocal motor neuropathy

“… 4 , 10 Notably, some patients with MMN will not have detectable conduction block. 11 – 13 Routine nerve conduction studies may miss conduction block if present proximally. 14 Activity-dependent conduction block, defined as a temporary conduction block induced by exercise, can also go undetected on routine nerve conduction studies.…”

“… 12 , 13 Conduction block may also be difficult to demonstrate in cases of advanced disease with severe, confluent denervation. 11 Though serum anti-GM1 ganglioside IgM antibodies may be increased in MMN, these antibodies are not sensitive markers for the disease since they may be detected in as few as 25% of patients. 15 …”

“…MMN occasionally may be misdiagnosed as motor neuron disease, progressive muscular atrophy, or lower motor neuron predominant amyotrophic lateral sclerosis (ALS). 11 However, clinical findings as summarized in Table 1 and electrophysiology can help differentiate these. 9 , 16 It is important to distinguish among these diseases as each has a dramatically different course.…”

“…In contrast, MMN frequently responds well to treatment with IVIG, giving patients the potential for a normal lifespan. 16 IVIG may also be used in a diagnostic trial 11 for confirmation if a diagnosis of MMN cannot be made on the basis of physical examination and electrodiagnostic studies. 11 …”

“…In those patients, IV cyclophosphamide may reset the immune system and provide prolonged recovery. 11 In this review, we will focus on the pharmacology, efficacy, safety, and tolerability of IVIG and SCIG infusion for treatment of MMN.…”