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Do A-waves help predict intravenous immunoglobulin response in multifocal motor neuropathy without block?
Dale J Lange1, Rajwinder Nijjar, Andrei Voustianiouk
1Department of Neurology, Division of Neuromuscular Disease, Mount Sinai School of Medicine, New York, New York, USA. langed@hss.edu
Muscle & Nerve
|February 10, 2011
Summary
Abnormal A-waves on electrophysiology may predict response to intravenous immunoglobulin (IVIg) therapy in lower motor neuron (LMN) syndromes. This finding holds true even without evidence of multifocal conduction block (MCB).
Area of Science:
- Neurology
- Electrophysiology
- Immunology
Background:
- Investigating predictors of treatment response in lower motor neuron (LMN) syndromes is crucial for optimizing patient care.
- Intravenous immunoglobulin (IVIg) is a potential therapy for certain neurological conditions, but its efficacy in LMN syndromes without multifocal conduction block (MCB) requires further elucidation.
- Identifying reliable biomarkers for IVIg responsiveness can guide therapeutic decisions and improve patient outcomes.
Purpose of the Study:
- To determine if specific electrophysiological findings can predict response to IVIg in patients diagnosed with LMN syndromes lacking MCB.
- To evaluate the impact of IVIg therapy on clinical and electrophysiological measures in this patient cohort.
Main Methods:
- A cohort of 9 patients with LMN syndromes without MCB received 18 weeks of IVIg therapy.
- Patient response was assessed at 2 and 18 weeks using the Appel Amyotrophic Lateral Sclerosis (AALS) score, ALS Functional Rating Scale (ALSFRS), and electrophysiological tests including motor unit estimates (MUNEs).
- Pretreatment electrophysiological studies were analyzed for specific findings, including 'abnormal A-waves'.
Main Results:
- No significant changes were observed in AALS or ALSFRS scores post-IVIg treatment.
- Seven patients (responders) showed increased grip and pincer strength, while two non-responders did not.
- Pretreatment 'abnormal A-waves' (complex, repetitive, or present in multiple nerves) were significantly more frequent in responders (P = 0.028).
Conclusions:
- The presence of 'abnormal A-waves' in electrophysiological studies may serve as a predictive marker for IVIg responsiveness in LMN syndromes.
- This predictive potential exists even in the absence of multifocal conduction block (MCB), suggesting a distinct pathophysiological mechanism.
- Further research is warranted to validate 'abnormal A-waves' as a reliable biomarker for guiding IVIg therapy in LMN syndromes.
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