Sara Contardi

Reliability of a driving simulation task for evaluation of sleepiness

Driving Simulators reproduce situations that require tracking and visual searching, the main features of real driving. This study measured the reliability of a monotonous driving scenario to detect the circadian variations of alertness in healthy subjects. Five men and five women underwent a monotonous 30 min driving simulation task every 2 h. Before each driving task subjects completed the Stanford Sleepiness Scale (SSS) and the Visual Analogue Scale (VAS) to correlate the subjective measurements of sleepiness to the objective data of the simulator. Driving performances deteriorated or improved according to the circadian variation of alertness. The scenario is suitable to detect the consequences of sleepiness related to the circadian variations of alertness. The standard deviation of lane position, comparing the differences among the 10 min blocks in each task is the parameter most significant for the evaluation of sleepiness.

A driving simulation task: correlations with Multiple Sleep Latency Test.

Sleepiness and driving is a dangerous combination that causes thousands of crashes each year resulting in injury and death. In the last few years, driving simulators have been used to study the performance decrements associated with drowsiness. We correlated performances of a driving simulation task in healthy volunteers in different alertness conditions with objective (MSLT: Multiple Sleep Latency Test) and subjective (SSS: Stanford Sleepiness Scale; VAS: Visual Analogue Scale) sleepiness measurements. The subjects were tested on two days, after a normal night of sleep and after a night of complete sleep deprivation. The study consists of four sessions of MSLT, each one followed by subjective measurements of sleepiness and by a 30 min driving simulation task with a monotonous driving scenario. The parameters that correlate most highly with MSLT are the standard deviation of lane position, the mean RT, crash frequency and exceeding the speed limit frequency. The monotonous driving simulation we adopted showed strong correlations with MSLT and subjective sleepiness scales in healthy subjects and is suitable to evaluate excessive daytime sleepiness in patients.

Daytime driving simulation performance and sleepiness in obstructive sleep apnoea patients

BACKGROUND Sleepiness related car accidents are common in obstructive sleep apnoea syndrome (OSAS) patients. The objective measurements of sleepiness used in clinical setting quantify the tendency to fall asleep in quiet situations that are completely different from driving. METHODS We studied 30 OSAS patients with subjective (subjective sleepiness scales) and objective (multiple sleep latency test, MSLT) sleepiness measurements, associated with driving simulation test (DST), previously validated in young healthy subjects. The results of subjective and objective sleepiness tests were compared with simulated driving performance in order to evaluate the suitability of our DST for measuring alertness. RESULTS Subjective and objective sleepiness measurements were significantly correlated with driving performance on the simulator. The most significant correlates of sleepiness were the measures of the primary vehicle control task on the simulator: lane position variability and crash data. The comparison of DST and MSLT results suggested our driving simulated approach could be used to evaluate daytime sleepiness in the clinical setting of OSAS patients. CONCLUSIONS Our DST is a suitable objective tool to detect sleepiness in OSAS patients, and could be useful in the clinical setting of sleep medicine and research.

Development of a disability scale for myotonic dystrophy type 1

Contardi S, Pizza F, Falzone F, D’Alessandro R, Avoni P, Di Stasi V, Montagna P, Liguori R. Development of a disability scale for myotonic dystrophy type 1. 
Acta Neurol Scand: 2012: 125: 431–438. 
© 2011 John Wiley & Sons A/S.

Automatic slow eye movement (SEM) detection of sleep onset in patients with obstructive sleep apnea syndrome (OSAS): Comparison between multiple sleep latency test (MSLT) and maintenance of wakefulness test (MWT)

OBJECTIVE To determine whether automatic slow eye movement (SEM) analysis performs comparably to standard sleep onset criteria at the multiple sleep latency test (MSLT) and at the maintenance of wakefulness test (MWT) in patients with obstructive sleep apnea syndrome (OSAS). METHODS We compared sleep latencies obtained upon standard analysis of MSLT and MWT recordings with automatically detected SEM latencies in a population of 20 severe OSAS patients that randomly underwent the two tests 1 week apart. RESULTS Eight of 20 OSAS patients had EDS as answered by the Epworth Sleepiness Scale (ESS). Mean SEM latency performed comparably to standard sleep onset in both the MSLT (6.4+/-5.5 min versus 7.4+/-5.1 min, p=0.25) and the MWT (25.2+/-14.5 min versus 24.4+/-14.0 min, p=0.45) settings. Mean SEM latency significantly correlated with the sleep latency at the MSLT (r=0.52, p<0.05) and at the MWT (r=0.74, p<0.001). Finally, the Epworth Sleepiness Scale score correlated with SEM latency at the MWT (r=-0.62, p<0.01), but not at the MSLT. CONCLUSIONS Automatic SEM detection performed comparably to standard polysomnographic assessment of sleep onset, thus providing a simplified technical requirement for the MSLT and the MWT. Further studies are warranted to evaluate SEM detection of sleep onset in other sleep disorders with excessive daytime sleepiness.

Simulated driving performance coupled with driver behaviour can predict the risk of sleepiness-related car accidents

Obstructive sleep apnoea syndrome (OSAS) is associated with the risk of sleepiness-related car accidents and worse driving simulator performances. Nevertheless, driving simulator studies failed to predict the real-world accident risk. Two-thirds of patients with OSAS will never experience a car crash, so that restricting their driving licence because of an OSAS diagnosis is not feasible.1 Our previous studies validated a 30 min monotonous driving scenario (STISIM 300 Driving Simulator, Systems Technology, Hawthorne, California, USA) versus subjective and objective measures of sleepiness in healthy volunteers undergoing …