Age-related Changes in Amplitude Ratio, Duration Ratio and Area Ratio in Nerve Conduction Studies

• Published in: Nihon Rōnen Igakkai zasshi Vol. 32; no. 8-9; pp. 547 - 552
• Main Authors: Kurokawa, Katsumi, Tanaka, Eiji, Nakayama, Takayasu, Maruyama, Hirofumi, Nakamura, Shigenobu, Mimori, Yasuyo, Yamashita, Hiroshi, Kohriyama, Tatsuo, Yukawa, Motoko
• Format: Journal Article
• Language: Japanese
• Published: Japan The Japan Geriatrics Society 1995
• Subjects: Action Potentials; Adolescent; Adult; Aged; Aging - physiology; Child; Compoung muscle action potential; Conduction block; Demyelinating Diseases - diagnosis; Humans; Middle Aged; Muscles - physiology; Muscles - physiopathology; Nerve conduction study; Neural Conduction; Peripheral Nerves - physiology; Peripheral Nerves - physiopathology; Sensory nerve action potential; Temporal dispersion
• ISSN: 0300-9173
• DOI: 10.3143/geriatrics.32.547

We investigated the effect of aging on nerve conduction parameters in 184 subjects (aged 10-75 years) without any history or signs of peripheral neuropathy, in order to clarify the diagnostic parameters of demyelinating neuropathies in the aged. The CMAP amplitude ratio (proximal CMAP/distal CMAP), duration ratio and area ratio remained unchanged throughout the second to eighth decades. The lower limits of normal CMAP amplitude ratio (mean -3SD) were 0.79 (median nerve), 0.74 (ulnar nerve), 0.59 (peroneal nerve), and 0.48 (tibial nerve). The upper limits of normal CMAP duration ratio (mean 11+3SD) were 1.22 (median nerve), 1.19 (ulnar nerve), 1.35 (peroneal nerve), and 1.32 (tibial nerve). The lower limits of normal CMAP area ratio (mean-3SD) were 0.84 (median nerve), 0.78 (ulnar nerve), 0.61 (peroneal nerve), and 0.62 (tibial nerve). There were no age-related changes in amplitude ratio or duration ratio of SNAP, although the standard deviations increased with age. Since the amplitude ratio, duration ratio and area ratio are simple and age-independent, they can provide useful and reliable information for routine nerve conduction studies for aged patients with demyelinating neuropathies.