Limitations of the computerized laryngeal analyzer (CLA) in the assessmentof the swallowing mechanism

This study was devised to assess the repeatability of measurements obtained from the Computerized Laryngeal Analyzer (CLA), a commercial system which monitors global laryngeal activity through a piezoelectric transducer posit ioned at the level of the thyroid cartilage. Twenty-two healthy subjects (3 7+/-7 yr) were asked to repeat three consecutive times the deglutition of t hree types of bolus: dry (saliva only), liquid (10 ml water) and solid (1 c m(3) biscuit). The whole recording session was repeated 4+/-3 days apart. T wo parameters were considered: amplitude and duration of the deglutition. B oth intra- and inter-sessions repeatability were assessed by the standard e rror of measurement. The amplitude measurements were often found to be clip ped at 100 mV, making duration the only parameter suitable for analysis. Th e duration was homogenous for the three types of bolus and no trend effect was found either intra- or inter-sessions. Inter-sessions repeatability was significantly lower than the intra-session one (P<0.05). As a practical im plication, a change in duration greater than or equal to 1 s (=65% of the o bserved mean value) between two separate measurements is required in order to be 95% confident that it is not due to chance alone. We conclude that th e observed limitations in the measurements provided by the CLA system, in c onjunction with its intrinsic characteristic of providing only an uncalibra ted measurement of global laryngeal activity, seriously question the possib ility of using the CLA system either as a diagnostic tool or as a substitut e of the gold standard method (videofluorography). (C) 2000 IPEM. Published by Elsevier Science Ltd. All rights reserved.