Sural/radial amplitude ratio in the diagnosis of mild axonal polyneuropathy

✍ Scribed by Seward B. Rutkove; Milind J. Kothari; Elizabeth M. Raynor; Michele L. Levy; Ricardo Fadic; Rachel A. Nardin

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 130 KB
• Volume: 20
• Category: Article
• ISSN: 0148-639X
• DOI: 10.1002/(sici)1097-4598(199710)20:10<1236::aid-mus5>3.0.co;2-d

✦ Synopsis

As proximal nerves are relatively spared in length-dependent, axonal polyneuropathy, we theorized that a sural/radial amplitude ratio (SRAR) might be a sensitive indicator of mild polyneuropathy. In this study, sural amplitudes and SRARs in patients with signs of mild axonal polyneuropathy were compared to those of normal, age-matched control subjects. Sural and radial sensory responses were measured in a standard fashion in all subjects. Thirty polyneuropathy patients had an average SRAR of 0.29 as compared to 0.71 for the 30 normal subjects. An SRAR of less than 0.40 was a strong predictor of axonal polyneuropathy, with 90% sensitivity and 90% specificity, as compared to an absolute sural amplitude of less than 6.0 µV, which had sensitivity of only 66%. Additionally, unlike the sural amplitude, the ratio did not vary significantly with age. We conclude that the SRAR is a sensitive, specific, age-independent electrodiagnostic test for mild axonal polyneuropathy.