Pitfalls in the evaluation of isometric strength (TQNE) data in ALS

The phase of rapid reduction of isometric strength in single muscle groups was identified and its slope was calculated in patients studied with the TQNE method. This parameter was studied in the extremities and in respiration in 4 ALS patients and 4 PMA (progressive spinal muscle atrophy) patients. The slopes of the strength reduction in these muscle groups and their mean values exceeded the slopes of the corresponding megascores; this difference was larger in the extremities than in respiration. It is concluded that repeated spirometry gives a good expression of reduction of muscle strength in ALS, and is well suited for monitoring treatment effects.