Driving performance in patients with chronic obstructive pulmonary disease.

Patients with chronic obstructive pulmonary disease (COPD) present with impairments of their cognitive performance. It is still unknown whether cognitive deficits influence driving abilities in patients with COPD. The present study investigates driving performance in patients with COPD and healthy controls. Driving simulation was performed in 17 patients with COPD and 10 healthy controls. Patients with COPD demonstrated significantly worse results in terms of accident frequency in the simulated driving situation. No correlations existed between the severity of disease, assessed from the polysomnographical findings (e.g., lung function, blood gas analysis, sleep disturbance, nocturnal ventilation, and oxygen saturation), and driving performance. We conclude that impairments of driving performance in patients with COPD cannot be predicted on the basis of the severity of the disease. The impairment of driving performance in the simulated driving situation in COPD patients may have crucial consequences for driving licensing in these patients.

[Cognitive deficits in patients with chronic obstructive pulmonary disease (COPD)]. / Kognitive Defizite bei Patienten mit chronisch-obstruktiver Atemwegserkrankung (COPD).

INTRODUCTION: Patients with COPD present with impairments of their cognitive performance. The present study compares intelligence and memory performance as well as different aspects of attention in COPD patients and healthy controls. Additionally, potential factors influencing daytime performance are analyzed. PATIENTS AND METHODS: Neuropsychological testing was performed in 32 patients with COPD and 10 normal controls. The following aspects were evaluated: memory, intelligence, simple, selective and divided attention, sustained attention under stress and under monotonous conditions. RESULTS: There were no differences between COPD patients and normals with regard to divided attention, vigilance and memory. Patients with COPD demonstrated significantly worse results in terms of intelligence (p < 0.01) as well as simple (p < 0.01), selective (p < 0.05) and sustained attention (p < 0.01). No correlation existed between the severity of the disease (lung function, blood gas analysis, nocturnal oxygen saturation) and neuropsychological findings. Merely a relationship between memory function and slow-wave sleep or REM sleep was demonstrated. CONCLUSION: Impairments of cognitive performance in patients with COPD cannot be predicted on the basis of the severity of the disease. Therefore neuropsychological testing is recommended, especially when impairment of daytime function has to be quantified.

Driving simulator and neuropsychological [corrected] testing in OSAS before and under CPAP therapy.

Patients with obstructive sleep apnoea syndrome (OSAS) have an increased car accident rate. Investigations on accident frequency are based on case history, insurance reports and driving simulator studies. The present study combines neuropsychological testing of different attention aspects engaged in driving a car and driving simulation to evaluate a suitable instrument for assessing therapeutic effects of continuous positive airway pressure (CPAP). Driving simulator investigation and neuropsychological testing of alertness, vigilance and divided attention were performed in 31 patients with polysomnographically confirmed OSAS (apnoea-hypopnoea index 24.8+/-21.5.h(-1)) before, and 2 and 42 days after initiation of CPAP. Divided attention and alertness improved significantly during CPAP, whereas vigilance remained unchanged. However, accident frequency (OSAS before therapy: 2.7+/-2.0; 2 days after CPAP: 1.5+/-1.4; 42 days after CPAP: 0.9+/-1.3) and frequency of concentration faults (OSAS before therapy: 12.4+/-5.1; 2 days after CPAP: 6.5+/-3.9; 42 days after CPAP: 4.9+/-3.3) decreased in the simulated driving situation after 2 and 42 days of therapy. There was no relation between accident frequency, concentration faults and daytime sleepiness, as measured by the Epworth Sleepiness Scale, and polysomnographic or neuropsychological findings, respectively. In conclusion, the present results suggest that driving simulation is a possible benchmark parameter of driving performance in obstructive sleep apnoea syndrome patients.

[Estimation of accident risk in obstructive sleep apnea syndrome (OSAS) by driving simulation]. / Abschätzung des Unfallrisikos bei obstruktivem Schlafapnoe-Syndrom (OSAS) durch Fahrsimulation.

Abstract. Patients with obstructive sleep apnea syndrome (OSAS) have an accident rate between two and seven times higher than normals. Investigations on accident frequency are based on case history, insurancy reports, and driving simulator investigations. The present controlled study was planned to test whether an increased accident risk could be demonstrated in patients with OSAS before and on CPAP (continuous positive airway pressure)-therapy using the driving simulator C.A.R. Driving simulator performance was investigated in 31 patients with polysomnographically confirmed OSAS (apnea-hypopnea-index 24.8 +/- 21.5/h) before, 2 and 42 days after initiation of CPAP and was compared to 10 healthy controls in whom OSAS was excluded by polysomnography. Driving simulator performance was significantly worse in OSAS as compared to normals especially in terms of accident frequency (OSAS: 2.7 +/- 2.0, controls: 1.3 +/- 1.5, p < 0.05) and concentration faults (OSAS: 12.4 +/- 5.1, controls: 7.1 +/- 3.2, p < 0.01). On CPAP accident frequency (OSAS before therapy: 12.4 +/- 5.1, 2 days CPAP: 1.5 +/- 1.4, p < 0.01; 42 days CPAP: 0.9 +/- 1.3, p < 0.001) and frequency of concentration faults (OSAS before therapy: 12.4 +/- 5.1, 2 days CPAP: 6.5 +/- 3.9, p < 0.001; 42 days CPAP: 4.9 +/- 3.3, p < 0.001) could be lowered significantly both in the short and medium term of therapy. The driving simulator C.A.R. is an adequate tool for the evaluation of an increased accident risk in OSAS-patients and demonstrates the efficiency of CPAP-therapy.

Enhanced responsiveness of human extravisual areas to photic stimulation in patients with severely reduced vision.

Lesions in the primary visual cortex induce severe loss of visual perception. Depending on the size of the lesion, the visual field might be affected by small scotomas, hemianopia, or complete loss of vision (cortical blindness). In many cases, the whole visual field of the patient is affected by the lesion, but diffuse light-dark discrimination remains (residual rudimentary vision, RRV). In other cases, a sparing of a few degrees can be found (severely reduced vision, SRV). In a follow-up study, we mapped visually induced cerebral activation of three subjects with SRV using functional magnetic resonance imaging. We were especially interested in the visual areas that would be activated if subjects could perceive the stimulus consciously although information flow from V1 to higher visual areas was strongly reduced or virtually absent. Because subjects were only able to discriminate strong light from darkness, we used goggles flashing intense red light at a frequency of 3 Hz for full visual field stimulation. Besides reduced activation in V1, we found activation in the parietal cortex, the frontal eye fields (FEF), and the supplementary eye fields (SEF). In all patients, FEF activation was pronounced in the right hemisphere. These patterns were never seen in healthy volunteers. In a patient who recovered completely, we observed that extrastriate activation disappeared in parallel with the visual field restitution. This result suggests that damage to the primary visual cortex changes the responsiveness of parietal and extravisual frontal areas in patients with SRV. This unexpected result might be explained by increased stimulus-related activation of attention-related networks.

['Frontal lobe syndrome' caused by severe head trauma or cerebrovascular diseases]. / "Frontalhirnsyndrom" nach Schädel-Hirn-Trauma oder zerebrovaskulären Erkrankungen.

The term "frontal lobe syndrome" comprises a variety of different clinical syndromes produced by focal lesions involving the prefrontal cortex. However, similar syndromes can be observed after lesions involving subcortical structures connected with the prefrontal cortex in neuronal networks. With respect to the different clinical pictures and underlying brain lesions, prefrontal lobe dysfunction may be divided into a disorganized type, caused by lesion of the dorsolateral prefrontal lobe and its connections, a disinhibited type that can be observed following lesions of the orbitofrontal cortex, and an apathetic type following lesions affecting the functional balance between the cingulum and the supplementary motor area. As intracerebral lesions are rarely limited to the brain regions described, in the majority of patients various degrees of behavioural dysfunction can be observed. The case reports of four patients illustrating the three major prefrontal syndromes following severe head injury (n = 2) or cerebrovascular disease (n = 2) are presented and diagnostic implications as well as possible treatment strategies are discussed.

Neuropsychological investigations and event-related potentials in obstructive sleep apnea syndrome before and during CPAP-therapy.

Patients with obstructive sleep apnea syndrome (OSAS) suffer from daytime sleepiness and a decline of cognitive functions. The study evaluated whether special cognitive disabilities predominate in OSAS. Besides the number connection test (ZVT), judging information processing and working velocity, computer-assisted (Wiener Testsystem and Zimmermann Testbatterie) neuropsychological testing was performed in 31 OSAS patients (50.1 +/- 9.4 years) before starting nasal continuous positive airway pressure (nCPAP) therapy. Identical test battery was performed in 10 male healthy volunteers (48 +/- 9.9 years). In addition visual evoked event-related potentials (ERPs) were recorded, the P3-component was evaluated. Impairment of alertness (P < 0.001), selective attention (P < 0.001) and continuous attention (P < 0.001) could be revealed, vigilance was not altered. Cognitive deficits were correlated with the degree of nocturnal hypoxemia. They were not linked to the apnea/hypopnea-index (AHI), arousal index or vigilance parameters. During 6 months of nCPAP-therapy (15 patients) alertness and continuous attention improved significantly (P < 0.01), intra-individual different pathological results persisted however. P3 latencies also remained prolonged. Chronic intermittent nocturnal hypoxemia in OSAS-patients obviously leads to cognitive deficits. ERP partially generated in subcortical cerebral structures represent a neurophysiological tool indicating brain dysfunction which cannot be evaluated by neuropsychological tests. Objective neuropsychological testing is needed in revealing therapeutic effects in OSAS-patients. Remaining deficits during sufficient nCPAP-therapy may reflect irreversible hypoxic cerebral damage.

[Event related potentials and neuropsychological studies in sleep apnea patients]. / Ereigniskorrelierte Potentiale und neuropsychologische Untersuchungen bei Schlafapnoepatienten.

Patients with obstructive sleep apnoea syndrome (OSAS) commonly complain about daytime sleepiness and a decline of cognitive functions. Several diagnostic tools have been established to judge objectively vigilance and cognitive impairment. Forty OSAS patients aged between 34 and 74 years were examined via several neuropsychological tests (e.g. vigilance test of the Wiener Testsystem, number connection test ("Zahlenverbindungstest-ZVT") to assess working velocity and information processing, d2-test to rate concentration on exertion) before starting continuous positive airway pressure (CPAP) therapy. In addition, visual evoked event-related potentials (ERPs) were recorded; the P3-component was evaluated. All patients subjectively stated daytime sleepiness and cognitive dysfunctions to variable degrees. Each patient showed at least one pathological result in the neuropsychological tests; vigilance impairment could be revealed only in 7 patients. P3-latencies were increased in OSAS patients when compared to age-matched controls (408.1 +/- 44.4 ms versus 373.4 +/- 32.5 ms; p < 0.03). P3-latencies and concentration on exertion showed a significant correlation with respect to the relative part of the total sleep time in which the patient's oxygen saturation was below 90% (p < 0.05). Thus it could be demonstrated that cognitive deficits in OSAS patients are a result of chronic intermittent oxyhaemoglobin desaturation rather than of a decline in daytime vigilance. ERPs represent an objective neurophysiological tool in neuropsychological examination. As they are also generated in subcortical cerebral structures they may indicate cognitive dysfunctions which cannot be evaluated by neuropsychological tests. If lead of ERPs is possible in special sleep centres they should be additionally used in the assessment of cognitive functions in OSAS patients.