Sylvia Kotterba

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.

Central fatigue assessed by transcranial magnetic stimulation

Central fatigue is a subjective phenomenon which can be examined using transcranial magnetic stimulation (TMS). To assess central fatigue, we compared TMS and peripheral electrical stimulations in patients with central nervous system (CNS) lesions and controls before and after an exhaustive task. The recovery times of motor evoked potential (MEP) amplitudes were significantly prolonged in the patient group whereas the recovery of F waves and compound muscle action potentials showed no significant changes. The results indicate that fatigue cannot be attributed either to intramuscular processes or to reduced spinal excitability, but reflects a supraspinal, probably cortical phenomenon. The measurement of MEP recovery times proved to be a simple and objective tool for the assessment of fatigue and for the differentiation between healthy controls and patients with CNS lesions.

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.

Assessment of Driving Performance in Patients with Relapsing-Remitting Multiple Sclerosis by a Driving Simulator

Objective: To compare the driving performance using a driving simulator with physical and cognitive functions as measured by the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Functional Composite (MSFC) in patients suffering from the relapsing-remitting form of multiple sclerosis (RRMS). Methods: 31 RRMS patients (18 women, 13 men, mean age 35.6 ± 8.3 years, EDSS 2.8 ± 1.4) were compared with 10 healthy controls (8 men, 2 woman, age 45.1 ± 7.8 years). Results: Compared with controls, the accident rate (5.3 ± 3.8 vs. 1.3 ± 1.5, p < 0.001) and concentration faults (21.1 ± 15.5 vs. 7.1 ± 2.6, p < 0.01) of RRMS patients using the driving simulator were increased. While there was no correlation with the EDSS score, the accident rate was correlated with the MSFC (r = –0.5, p < 0.05). Regarding the three dimensions of the MSFC, accidents were related to the number of correct answers and Z-score in the paced auditory serial addition test (PASAT) as a measure for cognitive function (r = –0.33, p < 0.05). Conclusion: The current study demonstrates the need to focus also on driving skills in MS patients. The risk of accidents should be evaluated after relapses in particular. However, there are great interindividual differences. In the MSFC, most deficits could be evaluated in the PASAT. As there was a significant correlation between the accident rate in the driving simulator and the PASAT results, accidents seem to be more influenced by cognitive decline than by physical impairment. This indicates that the MSFC is a broader, more dimensional scale than the EDSS and should be preferred in the case of driving assessment. At the present time, the driving simulator seems to be a useful instrument judging driving ability, especially in cases with ambiguous neuropsychological results.

Comparison of driving simulator performance and neuropsychological testing in Narcolepsy

Daytime sleepiness and cataplexy can increase automobile accident rates in narcolepsy. Several countries have produced guidelines for issuing a driving license. The aim of the study was to compare driving simulator performance and neuropsychological test results in narcolepsy in order to evaluate their predictive value regarding driving ability. Thirteen patients with narcolepsy (age: 41.5+/-12.9 years) and 10 healthy control patients (age: 55.1+/-7.8 years) were investigated. By computer-assisted neuropsychological testing, vigilance, alertness and divided attention were assessed. In a driving simulator patients and controls had to drive on a highway for 60 min (mean speed of 100 km/h). Different weather and daytime conditions and obstacles were presented. Epworth Sleepiness Scale-Scores were significantly raised (narcolepsy patients: 16.7+/-5.1, controls: 6.6+/-3.6, P < or = 0.001). The accident rate of the control patients increased (3.2+/-1.8 versus 1.3+/-1.5, P < or = 0.01). Significant differences in concentration lapses (e.g. tracking errors and deviation from speed limit) could not be revealed (9.8+/-3.5 versus 7.1+/-3.2, pns). Follow-up investigation in five patients after an optimising therapy could demonstrate the decrease in accidents due to concentration lapses (P < or = 0.05). Neuropsychological testing (expressed as percentage compared to a standardised control population) revealed deficits in alertness (32.3+/-28.6). Mean percentage scores of divided attention (56.9+/-25.4) and vigilance (58.7+/-26.8) were in a normal range. There was, however, a high inter-individual difference. There was no correlation between driving performance and neuropsychological test results or ESS Score. Neuropsychological test results did not significantly change in the follow-up. The difficulties encountered by the narcolepsy patient in remaining alert may account for sleep-related motor vehicle accidents. Driving simulator investigations are closely related to real traffic situations than isolated neuropsychological tests. At the present time the driving simulator seems to be a useful instrument judging driving ability especially in cases with ambiguous neuropsychological results.

Respiratory monitoring in neuromuscular disease — capnography as an additional tool?

Daytime complaints like fatigue, sleepiness and cognitive dysfunction in neuromuscular disease can be due to nocturnal hypercapnia and hypoxemia. Daytime respiratory diagnostics does not reflect sleep disordered breathing. Nocturnal pulse oxymetry and capnography were performed in 11 patients (15-75 years old) with different slowly progressive neuromuscular diseases. Only four patients complained of dyspnea. Pulmonary function was abnormal in three patients. Blood gas samples showed a hypoxemia in three patients. Pulse oxymetry results were pathological in six patients. Nine patients presented abnormal capnographies. According to these results either nocturnal oxygen application was initiated or ventilatory parameters were modified. Daytime symptoms and muscular strength improved markedly. Capnography and pulse oxymetry should be performed during the course of neuromuscular disease to detect respiratory insufficiency. Capnography seems to be a more sensitive indicator for respiratory impairment especially when artificial ventilation has been initiated.

Begutachtung der Tagesschläfrigkeit bei neurologischen Erkrankungen und dem obstruktiven Schlafapnoesyndrom (OSAS)

ZusammenfassungPatienten mit erhöhter Tagesschläfrigkeit sind in allen Bereichen des sozialen Umfeldes beeinträchtigt. Gutachterliche Stellungnahmen werden im Rentenverfahren, zur Beurteilung der Einsatzmöglichkeiten am Arbeitsplatz und zur Fahrtauglichkeit gefordert. Der Gutachter muss zur Objektivierung der Schläfrigkeit geeignete Testverfahren auswählen. Vor der endgültigen Begutachtung sollten alle schlafmedizinischen Differenzialdiagnosen abgeklärt und eine optimale Behandlung angestrebt worden sein. Gesetzliche Regelungen für die Bewertung von Schläfrigkeit liegen in den Leitlinien zur Begutachtung der Kraftfahreignung vor. Die Bedeutung der Tagesschläfrigkeit in anderen Berufsgruppen ist arbeitsplatzbezogen zu bewerten. Die Bewertung sollte dem Patienten im Hinblick auf Berufswahl und Arbeitsplatzgestaltung mitgeteilt werden. Der Gutachter hat somit die verantwortungsvolle Aufgabe, eine fachübergreifende Differenzialdiagnostik pathologischer Schläfrigkeit durchzuführen und durch geeignete Untersuchungsverfahren Therapieerfolge zu kontrollieren. Die vorliegende Übersicht soll gesetzliche Grundlagen und geeignete Untersuchungsverfahren darstellen.AbstractPatients with increased daytime sleepiness are impaired in all areas of their social environment. Expert opinions are recommended for pension proceedings, regarding driving licenses as well as for restrictions at the workplace. All possibilities should be considered in the differential diagnosis of sleep disorders, which have to be treated before an expert opinion is submitted. Statutory regulations on evaluation of sleepiness are contained in the guidelines for assessing a patient’s fitness to drive. The importance of daytime sleepiness in other occupations should be assessed according to the respective workplace. The patient should be informed of the appraisal with regard to career choice and workplace design. The expert thus has the responsible task of carrying out interdisciplinary differential diagnosis of pathological sleepiness and monitoring treatment success with appropriate test methods. In the present paper the legal guidelines in Germany and available test methods are presented.

Quality of life in restless legs syndrome. Influence of daytime sleepiness and fatigue

ZusammenfassungHintergrund und Ziel:Das Restless-Legs-Syndrom (RLS) stellt eine häufige neurologische Erkrankung dar, die durch unangenehme Missempfindungen in den Beinen und motorische Unruhe insbesondere in Ruhe und nachts charakterisiert ist. Diskutiert werden das Ausmaß der aus den nächtlichen Problemen resultierenden Tagesschläfrigkeit und Fatigue und ihr Einfluss auf die Lebensqualität des Patienten. In der vorliegenden Studie sollen unterschiedliche Skalen zur Quantifizierung der Tagessymptomatik verglichen werden.Patienten und Methodik:Untersucht wurden 28 RLS-Patienten (19 Frauen, neun Männer, 58,6 ± 11,9 Jahre alt), davon 78% mit einer schweren Form, mittels der Epworth Sleepiness Scale (ESS), der Fatigue Severity Scale (FSS) und des Lebensqualitätsfragebogens SF-36.Ergebnisse:Jeweils 17 Patienten wiesen eine vermehrte Schläfrigkeit (ESS) und Fatigue (FSS) auf, wobei diese Symptome nicht korrelierten. Subskalen des SF-36 beurteilen entweder eher physische oder mentale Komponenten. Hier ergab sich eine stärkere Einschränkung der physischen Gesundheit bei höheren Fatigue-Werten, eine Einschränkung der mentalen Gesundheit eher bei erhöhter Tagesschläfrigkeit.Schlussfolgerung:Eine Beeinträchtigung der Tagessymptomatik und Lebensqualität durch das RLS lässt sich somit eindeutig belegen. Unterschiedliche Skalen sollten zur objektiven Quantifizierung eingesetzt werden, um eine differenzierte Therapie planen zu können.AbstractBackground and Purpose:Restless legs syndrome (RLS) is a frequent neurologic disorder characterized by leg paresthesia and motor restlessness. It is still under debate to which amount the disease affects quality of life as it causes daytime sleepiness and fatigue. The presented study evaluates the daytime problems by different scales.Patients and Methods:28 patients (19 women, nine men, aged 58.6 ± 11.9 years) with RLS (78% with a severe form) were evaluated with the Epworth Sleepiness Scale (ESS), the Fatigue Severity Scale (FSS) and the SF-36 to judge quality of life. Subscales of the SF-36 contain either rather physical or mental components.Results:17/28 patients showed an increased daytime sleepiness (ESS) and 17/28 increased fatigue (FSS), whereby these symptoms did not correlate. With regard to the SF-36 scores higher values of fatigue caused a greater limitation of the physical health, daytime sleepiness correlated with limitation of the mental health.Conclusion:The study clearly demonstrates an impairment by fatigue and daytime sleepiness in RLS patients. Daytime symptoms worsen quality of life. Different scales have to be used to measure the different daytime symptoms. Therapy must be adjusted to the leading symptoms (e. g., stimulants in daytime sleepiness).

Hemifacial spasm or somatoform disorder – postexcitatory inhibition after transcranial magnetic cortical stimulation asa diagnostic tool

Hemifacial spasm (HFS) presents a frequent movement disorder. It is thought to have an organic origin. It therefore has to be distinguished from other facial involuntary movements, especially psychogenic tics, because the therapeutic approach differs. The present study opted to evaluate the diagnostic value of the postexcitatory inhibition (pI) after transcranial magnetic stimulation (TMS). After stimulating the contralateral hemisphere with the conventional flat coil and recording from the mentalis muscle, in 10 healthy controls and 10 patients postexcitatory inhibition was determined. PI showed no side to side difference in healthy controls (96.9±12.7 ms right, 87.9±10.8 ms left side, interhemispheric difference 6.4±3.8 ms). In 8 patients with hemifacial spasm, the duration of pI on the non‐affected side did not differ from the healthy controls (87.9±43.5 ms). During spasm, pI on the affected side shortened increasingly until no inhibition could be induced. Afterwards the spasm pI was prolonged significantly (up to 140 ms longer than opposite side) before returning to normal values. Two patients presented no side differences of pI during the “spasm”. An emotional conflict situation could be evaluated, supporting the diagnosis of somatoform disorder. As postexcitatory inhibition is mainly due to cerebral mechanisms, the electrophysiological results of the study pointed to a cortical influence on the hemifacial spasm. TMS seems to be an electrophysiological tool which allows a differentiation between organic and psychogenic spasm and enables a different therapeutic approach.

Polysomnography in acute African trypanosomiasis.

Sirs: Sleeping sickness is one of the sleep disorders listed in the International Classification of Sleep Disorders (3.C.1). To date there have been only few reports of sleep studies in chronic sleeping sickness [1, 2, 3] and, to our knowledge, no reports of sleep studies in acute sleeping sickness. We describe a case of acute African trypanosomiasis with disturbed sleep following travel to the tropics and the results of the sleep studies in this patient. A 47-year-old woman was admitted to hospital because of high remittent fever, insomnia during night, hypersomnia by day, and jaundice. Symptoms had started 5 days prior to admission, 7 days after returning from a 20-day trip to Zambia, Zimbabwe, and Tanzania. The patient had a fever of 39.2°C, an ulcerated and indurated lesion of 3 cm in diameter at the right first carpometacarpal joint, discrete nontender axillary lymphadenopathy on the right side, and jaundice. Abdominal ultrasound, chest radiography, and echocardiography on the day of admission were completely normal. Three blood cultures and microscopy of blood smears isolated no organisms. During the next 2 days her condition deteriorated, fever rose to 40.9°C, she became more sleepy during the day and was restless at night, and developed multiorgan failure with hepatitis, myocarditis, nephritis, pancreatitis, polyserositis, and disseminated intravascular coagulation. Again, microscopy of peripheral blood smears was performed, and this time trypanosomes were found. The indirect fluorescent antibody test for African trypanosomiasis was initially negative but turned positive (1:20) during the following 3 days. Due to the history, clinical findings, and microscopy results acute infection with Trypanosoma brucei rhodesiense with septic and multiorgan involvement was diagnosed. Treatment with suramin was initiated immediately, and she recovered completely over the following days. Lumbar puncture was performed on day 9 of suramin treatment, when there were no more trypanosomes in the peripheral blood smear, and the platelet count was normal; this yielded no direct evidence of central nervous system involvement. Total protein level of the spinal fluid was slightly elevated (0.65 g/l), but there was an increase neither in cells nor in the IgM level. Free immunoglobulin light chains were not present. Polysomnography was performed according to widely accepted methods on days 7, 9, and 15 and 6 months after the onset of trypanosomiasis [4]. Sleep was staged manually using the methods of Rechtschaffen and Kales [5], and arousals and leg movements were classified according to ASDA recommendations [6, 7]. Sleep examination revealed a poor sleep efficiency and decreased slow wave sleep, while the amount of arousals and awakenings was increased (Table 1). Furthermore, the patient had periodic limb movements (PLM) during sleep with a PLM index of 27.2/h and a PLM arousal and wake index of 11.7/h. Repeat polysomnographic measurements during follow-up showed an increase in sleep efficiency and amount of slow wave sleep and a decrease in arousals and awakenings, but PLM remained. MRI of the brain conducted on day 10 of disease onset showed a small angioma at the right frontal pole and was otherwise unremarkable. Mobile long-term EEG recording (24 h duration) was performed on day 22. The eight-channel monitoring revealed an alpha rhythm (10/s) with recurrent short naps (nonrapid eye movement sleep 2) during the day. Night recording confirmed polysomnographic data showing a poor sleep efficiency with frequent awakenings and arousals. At sleep onset generalized high theta activity and steep potentials were observed. There were no signs of encephalitis. Laboratory examination on day 25 after onset of the disease showed normal values for vitamin B1, vitamin B6, and vitamin E. The nerve conduction study using surface electrodes to record compound muscle action potentials revealed prolonged conduction velocity of the right peroneal nerve (38 m/s), left tibial nerve (34 m/s), and left LETTER TO THE EDITORS