ALS News TodayNew Split-Hand Index Identifies ALS Patients at Early Disease Stages, Study Shows

The split-hand sign, one of the first physical symptoms of ALS, refers to a loss of the pincer grasp caused by weakening and wasting of two hand muscles placed on the side of the thumb: the abductor pollicis brevis (APB) and the first dorsal interosseous (FDI). Hand muscles on the side of the little finger, such as the abductor digiti minimi (ADM), are typically spared, hence the term “split.” Several studies have attempted to develop split-hand indexes (SIs) based on a measure of muscle conduction known as compound muscle action potentials (CMAP) of affected and unaffected hand muscles over the years.

The CMAP and F-wave persistence (FP) of three important groups of hand muscles — APB, FDI, and ADM — were assessed in 83 ALS patients and 50 age- and height-matched healthy individuals (controls) in this study. The sensitivity and specificity of SIFP and SICMAP in identifying ALS patients from healthy participants were compared using statistical analysis. When compared to controls, both SIFP and SICMAP tended to have very low values in people with ALS.