Dynamic 320-slice CT larynx for detection and management of idiopathic bilateral vocal cord paralysis.

Idiopathic bilateral vocal cord paralysis (VCP) is a rare and difficult condition often undiagnosed and frequently confused with asthma and other respiratory conditions. Accurate diagnosis is crucial since 80% of cases patients require surgical intervention, such as tracheostomy or laser surgery, to relieve symptoms. The "gold standard" for diagnosing VCP has been laryngoscopy. In this case study, we demonstrate for the first time that idiopathic bilateral VCP can be accurately diagnosed by means of a novel noninvasive methodology: dynamic volume 320-slice computed tomography larynx. Three-dimensional reconstruction of laryngeal motion during the breathing cycle permitted functional assessment of the larynx showing absence of vocal cord movements. The new methodology may be valuable for noninvasive diagnosis of vocal cord movement disorders before and for follow-up after surgery.

Abnormal vocal cord function in difficult-to-treat asthma.

RATIONALE: Upper airway dysfunction may complicate asthma but has been largely ignored as an etiological factor. Diagnosis using endoscopic evaluation of vocal cord function is difficult to quantify, with limited clinical application. OBJECTIVES: A novel imaging technique, dynamic 320-slice computerized tomography (CT), was used to examine laryngeal behavior in healthy individuals and individuals with asthma. METHODS: Vocal cord movement was imaged using 320-slice CT larynx. Healthy volunteers were studied to develop and validate an analysis algorithm for quantification of normal vocal cord function. Further studies were then conducted in 46 patients with difficult-to-treat asthma. MEASUREMENTS AND MAIN RESULTS: Vocal cord movement was quantified over the breathing cycle by CT using the ratio of vocal cord diameter to tracheal diameter. Normal limits were calculated, validated, and applied to evaluate difficult-to-treat asthma. Vocal cord movement was abnormal with excessive narrowing in 23 of 46 (50%) patients with asthma and severe in 9 (19%) patients (abnormal > 50% of inspiration or expiration time). Imaging also revealed that laryngeal dysfunction characterized the movement abnormality rather than isolated vocal cord dysfunction. CONCLUSIONS: Noninvasive quantification of laryngeal movement was achieved using CT larynx. Significant numbers of patients with difficult-to-treat asthma had excessive narrowing of the vocal cords. This new approach has identified frequent upper airway dysfunction in asthma with potential implications for disease control and treatment.

Putting things into perspective: individual differences in working-memory span and the integration of information.

An important function of working memory is the integration of incoming information into an appropriate model of the contextual situation. We hypothesized that individual variability in working-memory function (estimated using Engle's operation-span measure) may lead to differential reactivity to a changing context. We recorded event-related brain potentials (ERPs) and reaction-time measures to stimuli embedded in long stimulus series (two auditory discrimination tasks), and examined the participants' responses in relation to how the current stimuli fit with the context generated by the previous stimuli. In both tasks, participants with low working-memory span scores showed larger brain responses as a function of variations in the local stimulus sequence than participants with high span scores. These data suggest that the low working-memory span group is more affected by the local stimulus sequence than the high span group, possibly because they are more easily swayed by ongoing changes and are therefore less capable of maintaining their attention on the overall sequence.