[Sleep disorders in neurological diseases]

Sleep disorders can be diagnosed in approximately 15 % of the population and have been shown to increase with age. The relationship between sleep disorders and neurological disorders, however, is still insufficiently considered in the clinical practice. Sleep disorders can be an early symptom of the disease, such as the presence of rapid eye movement (REM) sleep behavior disorder (RBD) as an early indicator of neurodegeneration. Sleep disorders have also been shown to be a main symptom of various neurological syndromes, such as in restless legs syndrome (RLS), periodic limb movement disorder (PLMD) and narcolepsy. The international classification of sleep disorders 2nd edition (ICSD 2) describes the main diagnoses, insomnia, circadian rhythm sleep disorders, sleep-related breathing disorders and hypersomnia but all of these can also appear as symptoms in various neurological diseases. Parasomnias are largely considered a differential diagnosis to nocturnal epilepsy. In this review, the main sleep disorders are described with a particular focus on how they relate to neurological diseases; in particular, how they influence disease-related symptoms and how they affect the course of the disease.

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.

[Sleep apnoea in women?--The forgotten gender]

The prevalence of clinically relevant, obstructive sleep apnoea syndrome (OSAS) in the general population is 2% in women and 4% in men. With increasing age and onset of postmenopausal status, the prevalence of OSAS in women becomes comparable to that of males. However, compared to prevalence data, women are under-represented in clinical sleep laboratories. The present overview deals with the potential reasons for clinical under-recognition of OSAS in women. The fact that OSAS frequency is underestimated in women probably derives from the atypical clinical symptoms, dominated by difficulties of initiating and maintaining sleep and by a depressive mood. There are several protecting mechanisms in women that prevent or postpone OSAS development to higher age groups or until the onset of menopause. These factors include craniofacial morphology and function, gender-specific body-fat distribution and hormonal influences on ventilation and dilating muscles in the oropharynx. Physicians should be aware of the presence of sleep-disordered breathing in women and of their special features.

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

Patients 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.

[Cognitive deficits in patients with chronic obstructive pulmonary disease (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.

[Long-term compliance of cpap-therapy--update, predictors and interventions]

CPAP (continuous positive airway pressure) is the therapy of choice for obstructive sleep apnea syndrome (OSAS). About 70 % of patients on CPAP use their device for at least 70 % of nights with an application-time of at least 4 hours per night. Severity of breathing disorder respectively disturbance of sleep architecture, degree of daytime sleepiness and patients' satisfaction with diagnostic and therapeutic procedures are good predictors of long-term CPAP-compliance. CPAP-compliance can be increased by intensive patient education. Alternative devices like for example Bilevel or auto-CPAP respectively cannot augment CPAP compliance.

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.

Fahrsimulatoruntersuchung bei Patienten mit obstruktivem Schlafapnoe-Syndrom: Konsequenzen für die Beurteilung der Fahrtüchtigkeit?

BACKGROUND AND OBJECTIVE

Patients with obstructive sleep apnea (OSA) have an increased accident risk. The German Society of Sleep Research and Sleep Medicine (DGSM) recommends for patients with OSA and daytime sleepiness that their driving ability should be re-established 6 weeks after the initiation of CPAP (continuous positive airway pressure), with documentation of therapeutic effects on daytime symptoms and performance. The present study was conducted to investigate whether an improvement of driving ability can be documented in neuropsychological tests and a simulated driving situation 14 days after the initiation of CPAP.

PATIENTS AND METHODS

Driving simulation and neuropsychological tests of vigilance were conducted in 36 patients (36 males, aged 54 9 years) with OSAS before and 2 (n=23), 14 (n=18) and 42 days (n=17) after initiation of CPAP.

RESULTS

Vigilance tests showed only slight changes under CPAP. Frequency of accidents during driving simulation was reduced after 14 days of CPAP, but a statistically remarkable decrease was achieved only on day 42. In contrast, concentration faults were reduced after 2 and 14 days of CPAP.

CONCLUSIONS

In OSA-patients improvement of daytime performance in a simulated driving situation can be documented 14 days after initiation of CPAP. There is need for investigating larger cohorts of patients so that current recommendations for driving licensing can be modified and permission to drive can be given earlier.

Diagnosis of multiple sclerosis: comparison of the Poser criteria and the new McDonald criteria

OBJECTIVES

A confident and accurate diagnosis of multiple sclerosis (MS) is important, but a specific diagnostic test for the disease does not exist. The traditional diagnostic criteria of Poser et al. were published in 1983, and recently, McDonald et al. recommended new criteria for the diagnosis of MS.

PATIENTS AND METHODS

In this study these two diagnostic schemes were compared by prospectively applying both of them to 76 patients with clinical features suggesting a new diagnosis of MS.

RESULTS

Using the Poser criteria, 29 patients (38%) were classified as clinically definite and 35 patients (46%) as laboratory definite MS. According to the new McDonald criteria, MS was diagnosed in 39 (52%) patients, 37 patients (48%) had 'possible MS'. All patients with a clinically definite MS with the Poser criteria were also given the diagnosis of MS as recommended by McDonald et al. Of those 35 patients with laboratory definite MS according to Poser et al., four patients could be classified as having MS with the McDonald criteria, 89% of them had 'possible MS'. Conversely, 75% of the 39 patients, who fulfilled the new McDonald criteria for MS were assigned to the category of clinically definite MS according to the Poser criteria, and 83% of the patients with a 'possible MS' using the McDonald criteria, had a laboratory definite MS with the Poser criteria.

CONCLUSION

MS according to the McDonald criteria was diagnosed more often than 'clinically definite MS' according to Poser et al., but combining the categories of clinically and laboratory definite MS, the diagnosis of MS could clearly be established more frequently using the Poser criteria.

Differenzierung von Müdigkeit und Fatigue bei Multipler Sklerose - Vergleich unterschiedlicher Messinstrumente

INTRODUCTION

Patients suffering from multiple sclerosis often complain of fatigue and sleepiness. Patients often cannot distinguish between these symptoms. Daytime sleepiness, attention and concentration deficits affect life quality severely. Usually symptoms of MS are characterized by the Expanded Disability Status Scale (EDSS). In new studies the MSFC proves to be a more sensitive method especially estimating the cognitive deficits.

METHODS

31 RRMS patients (18 women, 13 men, mean age 35.6 +/- 8.3 years) and 19 healthy controls (9 men, 1 woman, age: 55.1 +/- 7.8 years) were assessed by: 1) morning and evening protocols of the German Sleep Society, 2) Epworth Sleepiness Scale (ESS), 3) Extended Disability Status Scale (EDSS), 4) MS Functional Composite (MSFC) based on arm function, ambulation and cognition (paced auditory serial addition test, PASAT), 5) Fatigue Severity Scale (FSS).

RESULTS

The EDSS-Score ranged from 1.0 to 6.5 (2.8 +/- 1.4). Mean Z-Score of MSFC was -0.19 +/- 0.63. Most deficits could be shown in the PASAT. Total sleep time correlated with recovery capacity of sleep (r = 0.42, P < 0.05). The ESS-Score was 6.1 +/- 2.9 (1 - 14). FSS-Score was raised with intraindividual variability (4,33 +/- 1.62, 1.4 - 7). The EDSS failed to correlate with the ESS- or FSS-Score. FSS correlated significantly with arm function (r = 0.465) und ambulation (r = 0.436) in the MSFC (P < 0.05).

DISCUSSION

MS-Patients are often not able to distinguish between fatigue and sleepiness. By using different scales judging sleepiness and fatigue significant differences could be evaluated. Fatigue is mainly linked to motoric deficits scored by the MSFC. Therefore medication with stimulants seems not to be useful in fatigue therapy.

[Accidents caused by sleepiness--prediction by neurophysiologic/psychologic testing and simulated driving studies]

Daytime sleepiness is a leading symptom of various diseases, and is an important cause of accidents at the workplace and on the road. For the evaluation of accident frequency, the medical history, neurophysiological and neuropsychological tests, and driving simulator performance are applied. The present paper describes these different methods, and assesses their value in predicting accidents. In the last resort, no single test suffices to evaluate the accident risk of patients suffering from daytime sleepiness--rather, a combination of the methods described is needed, in particular when an expert opinion on a patient's ability to drive is required. To date, no controlled studies have been done to compare the predictive value of the methods considered herein. Our results suggest that the nearness of driving simulation to reality makes it a suitable additional test method, in particular for the monitoring of results under treatment.

[Estimation of accident risk in obstructive sleep apnea syndrome (OSAS) by driving simulation]

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.

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.

Cytomegalovirus infection in systemic necrotizing vasculitis: causative agent or opportunistic infection?

We report on a 69-year-old woman who presented with myalgia, hearing impairment, fever, night sweats, weight loss, muscular weakness, paresthesia, hypesthesia, and hypalgesia. Sural nerve biopsy showed demyelinative and axonal polyneuropathy due to necrotizing vasculitis with fibrinoid necrosis. A positive test for antineutrophil cytoplasmic antibodies (ANCA) with a perinuclear immunofluorescence pattern directed against myeloperoxidase was more suggestive of microscopic polyangiitis (MPA) than of polyarteritis nodosa (PAN), the possible differential diagnoses. In addition, positive tests for cytomegalovirus (CMV) antibodies (immunoglobulin (Ig)M and IgG) and the detection of CMV-DNA in sputum specimens by polymerase chain reaction (PCR) were indicative of active CMV infection. Treatment with ganciclovir and anti-CMV immunoglobulin in addition to prednisolone medication for 6 months resulted in rapid improvement of the clinical symptoms without relapse. CMV infection has been described to be related to ANCA-associated vasculitis in non-immunocompromized patients and may be either a causative agent or an opportunistic infection. Identification of a viral etiology in patients with atypical ANCA-associated vasculitides may lead to different, less aggressive treatment approaches, including antiviral therapy.

Hemifacial spasm or somatoform disorder--postexcitatory inhibition after transcranial magnetic cortical stimulation as a 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.

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.

[Coping style and cognitive attitude in patients with multiple sclerosis]

Recent literature revealed the importance of subjective coping strategies in chronic diseases. Due to the unpredictable course of the disease, multiple sclerosis patients have to integrate the illness into their psychosocial context. The present study examines the connection between coping styles, cognitive attitudes ("locus of control") and course in 20 outpatients with multiple sclerosis. Favourable coping strategies correlated with internal locus of control. Unfavourable coping behaviour on the other hand was correlated with external cognitive attitudes and a worse outcome. Moreover, depressive coping styles and psychopathological depression dominate with a worse course of the disease. Thus coping and cognitive attitudes have to be evaluated in order to strengthen personal resources in dealing with multiple sclerosis.

[Event related potentials and neuropsychological studies in sleep apnea patients]

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.

Cortical reorganization in patients with facial palsy

Possible changes in the organization of the cortex in patients with facial palsy, serving as a model of peripheral motor deefferentation, were investigated by using transcranial magnetic stimulation (TMS) and positron emission tomography (PET). With TMS, the size of the area producing muscle-evoked potentials (MEPs) of the abductor pollicis brevis muscle, the sum of MEP amplitudes within this area, and the volume over the mapping area were compared between both hemispheres in 8 patients. With PET, increases in regional cerebral blood flow, measured with the standard H2(15)O2 bolus injection technique, were compared between 6 patients and 6 healthy volunteers during sequential finger opposition. Patients moved the hand ipsilateral to the facial palsy, the control subjects the right hand. Of 9 patients in total, 5 participated in both experiments. With both methods, an enlargement of the hand field contralateral to the facial palsy was found, extending in a lateral direction, into the site of the presumed face area. The PET data showed that the enlargement of the hand field in the somatosensory cortex (SMC) is part of a widespread cortical reorganization, including the ipsilateral SMC and bilateral secondary motor and sensory areas. We report for the first time, using two different noninvasive methods, that peripheral, mere motor deefferentation is a sufficient stimulus for reorganizational changes in the healthy adult human cortex.

Perioperative lesions of the facial nerve: follow-up investigations using transcranial magnetic stimulation

Peripheral facial palsy can occur after aural surgery and neurosurgery. Routine neurophysiological investigation (utilizing electrical stimulation and the blink reflex) does not allow the direct assessment of the site of a lesion. In the present study transcranial magnetic stimulation (TMS) was applied in order to evaluate the usefulness of this method for prognosis. Twenty-three patients with postoperative facial pareses (after removals of an acoustic neuroma in 12 patients and parotid tumors in 11) were investigated. Ipsilateral short-latency and contralateral long-latency responses (after cortex stimulation) were elicited. At the first examination (11.7 +/- 9 days after onset of the palsy) the components of the blink reflex were absent in all cases. Responses to electrical stimulation were abnormal in 80%. Ipsilateral short-latency responses after TMS could be obtained in 7 patients. Pathological long-latency TMS responses were elicited in 17 patients. Follow-up investigations up to 2 years revealed no prognostic aspects from peripheral electrical stimulation, the blink reflex and the short-latency TMS response. The absence or extent of delay in long-latency responses at first examination was strongly correlated with final clinical outcomes. As improvements of the responses preceded clinical regressions of the paresis, TMS proved to be an important neurophysiological method for an early prognosis of recovery after perioperative lesions of the facial nerve.

[Acoustic evoked potentials (AEP) in obstructive sleep apnea syndrome]

Patients with obstructive sleep apnea syndrome (OSAS) present upper airway obstruction during sleep which can be documented by electromyography. The cause of weakness in oropharyngeal muscles is still unknown. Lesions of pons and medulla oblongata have to be expected. Brainstem auditory evoked potentials (BAEP) may indicate pathological changes in these regions. Several studies described normal BAEP in OSAS-patients. Moderate forms of OSAS as well as central sleep apnea syndromes were investigated, however. In our study 20 patients (17 men, 3 women, mean age 53.9 +/- 2.1 ys) with severe OSAS (apnea/hypopnea-index: 34.2 +/- 14.1/h, part of O2-saturation < or = 90% during sleep (SaO2 < or = 90%): 13.5 +/- 4.2%, minimal nocturnal O2-saturation: 78.0 +/- 2.5%) before starting nCPAP-therapy were investigated. BAEP were elicited after applying clicks 70 dB above threshold to each ear. Means of single wave latencies as well as interpeak latencies (I-V, I-III, III-V) were delayed significantly compared to normal controls. Main prolongations were seen regarding wave latency I (p < or = 0.001) and-interpeak latency I-V (p < or = 0.001). Prolongation of interpeak latencies (mean +/- 2.5 SD) of one or two sides could be demonstrated in 12 out of 20 patients. Pontomesencephal lesions (9 patients) dominated. There was no connection with respiratory parameters. As against pathological BAEP changes correlated with the duration of the disease. In conclusion pathological BAEP indicating brainstem lesions were seen in 60% of the examined OSAS-patients. Mesencephal lesions dominated, number of lesions increased with duration of disease. Therefore pathological findings have not to be considered as cause but as a result of hypoxemia in OSAS. Pathological BAEP may reveal a higher risk for cerebrovascular stroke. Therefore these patients should be leaded to further cerebrovascular investigation.

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.

Follow-up investigations of peripheral facial palsy by transcranial magnetic stimulation

Twenty-three patients (10 men, 13 women; age: from 23 to 81 years, mean 52 years) with Bell's palsy were investigated by magneto-electrical stimulation in order to evaluate the usefulness of this method for prognostication. At each examination the facial nerve was electrically stimulated, and an orbicularis-oculi-reflex was elicited. Follow-up investigations were possible in 13 patients. All patients showed pathological long- and short-latency responses at the first examination. The blink reflex examination revealed a pathological result in all cases. The responses to electrical stimulation were pathological only in 35%. The follow-up examinations revealed that the analysis of the short-latency response did not give a prognostic information. In contrast, maintained elicitation of the long-latency response pointed to a favourable prognosis. In follow-up investigations, the increase of amplitude and the decrease of latency of the long-latency response correlated with a complete recovery, while the decrease of amplitude and the increase of latency correlated with a partial recovery. The improvement of the responses in magnetic stimulation preceded the clinical improvement. By using magnetic stimulation, an early registration and evaluation of the course of Bell's palsy are possible.

[Transcranial magnetic stimulation in diagnosis of trigeminal neuralgia]

Patients with trigeminal neuralgia are usually investigated by elicitation of the orbicularis oculi reflex and trigeminal evoked potentials. These neurophysiological methods do not allow direct judgement of the trigeminal nerve. By transcranial magnetic stimulation, however, non-invasive investigation of the efferent part of the trigeminal nerve is possible. 10 patients (4 men, 6 women, aged from 43 to 73 years) with trigeminal neuralgia affecting the second or third division were examined. In all patients bilateral long-latency responses after stimulation of the tractus corticonuclearis and short-latency responses after stimulation of the proximal part of the trigeminal nerve were registered. 8 patients showed normal short- and long-latency responses, while in one other patient the long-latency responses were delayed on both sides. The remaining patient revealed a significant difference of amplitude compared to the contralateral long-latency response. This patient had a pontine lesion as shown by blink reflex and a pathological trigeminal evoked potential. In both these latter patients multiple sclerosis was diagnosed. Use of transcranial magnetic stimulation may thus prove helpful in the differential diagnosis of neurological disorders presenting with trigeminal neuralgia.

A rare manifestation of von Recklinghausen neurofibromatosis: advanced neurofibromatous infiltration in lung of a HIV-positive patient

This is a report of a 28-year-old HIV+ man with extensive involvement of lungs, spinal roots and peripheral nerves by neurofibromatosis von Recklinghausen. Huge masses (neurofibromas) ventral of the spine, which already infiltrated into the foramina intervertebralia, could be located by magnetic resonance imaging and high resolution computer tomography. Strikingly, most biopsies taken by bronchoscopy of the bronchial wall from various parts of the airways revealed extended infiltration by neurofibromas in submucosal areas, but no malignant tissue components. In addition, HIV infection with low CD4/CD8 ratio (0.1) and low CD4+ cells (160/microliters) was found.

[Transcranial magnetic stimulation in perioperative damage to the facial nerve]

5 patients (3 men, 2 women, aged from 28 to 51 years) with unilateral facial palsy after surgery of a cerebellopontine angle tumour have been investigated by transcranial magnetic stimulation. The purpose was to evaluate the prognostic aspects of this method, which was compared with the electrical stimulation of the facial nerve and the elicitation of an orbicularis-oculi reflex. The components of the blink reflex were absent in all cases. In 3 patients electrical stimulation was possible (compound muscle action potentials were delayed). With transcranial magnetic stimulation ipsilateral short-latency and contralateral long-latency responses (stimulation of the cortex) were elicited and registered from the M. mentalis as well as 3 times from the M. orbicularis oculi. The short-latency response revealed no prognostic aspects. Despite the missing response, a recovery was possible. Long-latency responses could be evoked in all patients. The extent of delay in latency was strongly correlated with clinical improvement of the paresis. Interestingly, this correlation could also be observed in the single rami of the facial nerve when two muscles were investigated in a patient. Transcranial magnetic stimulation is an important improvement in electrophysiological diagnosis of perioperative lesion of facial nerve to prove continuity of the nerve and to evaluate the clinical course.