decremental response
Progressive decline in CMAP amplitude during repetitive nerve stimulation, indicating neuromuscular junction dysfunction.
Full Definition
A decremental response refers to the progressive reduction in compound muscle action potential amplitude during repetitive nerve stimulation at low frequencies (typically 2-3 Hz). This finding indicates impaired neuromuscular transmission and is pathognomonic of neuromuscular junction disorders such as myasthenia gravis. A decrement greater than 10% between the first and fourth responses is considered abnormal. The decremental response may be more pronounced with exercise or improved with rest, reflecting the clinical fluctuation characteristic of myasthenic disorders.
Usage
Usage note: Always specify the percentage decrement and testing conditions.
In Context
- "A 15% decremental response was observed during repetitive stimulation of the facial nerve." — RNS study report
- "The decremental response improved following edrophonium administration, confirming the diagnosis." — Pharmacologic testing