Impact of sleep deprivation and obstructive sleep apnea syndrome on daytime vigilance and driving performance: a laboratory perspective.

INTRODUCTION: To study the impact of sleepiness, a well-established cause of car accidents, on driving ability, we designed a 30-min monotonous simulated driving task. MATERIALS AND METHODS: Our simulated driving task encompasses both primary vehicle control (standard deviation of lane position, crash occurrence) and secondary tasks (type and reaction times to divided attention tasks). Driving simulator data were correlated to subjective (state/trait) and objective (MSLT/MWT) sleepiness measures in healthy subjects undergoing sleep deprivation (SD) and in obstructive sleep apnea (OSAS) patients. RESULTS: SD induced severe sleepiness during nighttime, when state sleepiness increased while primary vehicle control ability worsened. After SD, driving ability decreased and was inversely correlated to subjective and objective sleepiness at MSLT. OSAS patients driving ability was well correlated to objective sleepiness, with inverse correlation to sleep propensity at the MSLT and even more strict relation with the ability to maintain wakefulness at the MWT. CONCLUSIONS: Sleepiness worsens driving ability in healthy subjects after SD and in OSAS patients. Driving ability correlates with subjective and objective sleepiness measures, in particular to the ability to maintain wakefulness.

Upper airway dynamics during negative expiratory pressure in apneic and non-apneic awake snorers.

BACKGROUND: The ability of negative expiratory pressure (NEP) technique to differentiate between awake snorers with and without obstructive sleep apnea-hypopnea (OSAH) was investigated. METHODS: Forty-eight subjects with sleep disordered breathing (SDB) and 7 healthy subjects, as non-snorer controls, underwent the NEP application of -5 and -7 cmH2O in the seated and supine position during wakefulness, after performing a sleep study. The upper airway collapsibility was assessed by computing the volume exhaled during the first 0.5 sec. (V,NEP0.5) and 1 sec. (V,NEP1) following the NEP start. RESULTS: Patients with severe (AHI > or = 30) (n = 19) and mild-to-moderate (AHI <30 and >5) (n = 15) OSAH had lower V,NEP0.5 (340 +/- 88 ml) as compared to snorers (AHI < or = 5) (n = 14) (427 +/- 101 ml; p < 0.01) and controls (n = 7) (492 +/- 69 ml; p < 0.001) in the supine position with NEP -5 cmH2O. Less significant differences among the different groups were observed for V,NEP0.5 in the seated position with NEP -5 cmH2O and in both positions with NEP -7 cmH2O (only OSAH patients vs controls, p < 0.001). Similar results were obtained for V,NEP1 in either position by using both NEP -5 cmH2O and -7 cmH2O. In spite of this, a substantial overlapping of V,NEP0.5 and V,NEP1 between snorers and OSAH patients did not allow to identify a reliable diagnostic cut-off level. An inverse correlation with AHI was found for V,NEP0.5 in the supine position with NEP -5 cmH2O (rs = -0.46, p < 0.05) in severe OSAH patients. CONCLUSION: The awake OSAH patients exhibit values of V,NEP0.5 and V,NEP1 lesser than those of awake snorers. The NEP technique, however, appears to have a limited usefulness as clinical tool for routine screening of the OSAH patients during wakefulness.

Wernicke-korsakoff encephalopathy and polyneuropathy after gastroplasty for morbid obesity: report of a case.

BACKGROUND: Gastric partitioning is a surgical procedure for the treatment of morbid obesity that may engender neurological complications, such as Wernicke encephalopathy and polyneuropathy. SETTING: A specialist hospital. PATIENT: A 36-year-old woman developed Wernicke-Korsakoff encephalopathy and polyneuropathy 3 months after gastroplasty for morbid obesity. A magnetic resonance scan documented the diagnosis, and a clear improvement occurred after parenteral thiamine treatment. In our patient and in previously described cases of the literature, postsurgical vomiting is a constant finding that seems to be the precipitating factor of neurological complications of gastric partitioning. CONCLUSION: Persistent vomiting after gastroplasty for morbid obesity should be considered an alarming symptom to treat immediately with appropriate measures.

Hypersomnia with periodic apneas in acquired micrognathia. A bird-like face syndrome.

We describe a syndrome characterized by acquired micrognathia, hypersomnia, and periodic apneas during sleep. Six patients affected with the syndrome underwent nocturnal and diurnal polygraphic recordings that demonstrated that during sleep there is an uninterrupted succession of apneas, primarily the obstructive type, analogous to those observed in Pickwickian syndrome. Simultaneous recording of pulmonary and systemic arterial pressure during sleep and repeated blood gas analyses have shown that as soon as the apneas appear there is a decisive increase in pulmonary and systemic pressure and serious alveolar hypoventilation. The hemodynamic and ventilatory changes are even more intense during rapid eye movement sleep. Tracheostomy, performed on five of our patients, is the only treatment producing complete clinical remission of the syndrome.

Muscular hypertrophy after chronic radiculopathy.

In four patients, calf muscular hypertrophy developed after the onset of sciatica. Hypertrophic muscles were weak and showed electromyographic signs of denervation. In all cases, calf muscle biopsy showed striking hypertrophy of type 1 and, especially, type 2 muscle fibers. This hypertrophy was associated with other signs indicating a neurogenic lesion. Muscle hypertrophy is a rare finding in neurogenic lesions. Stretch and exercise of muscle are probably the causative factors.

Paroxysmal arousals during sleep.

Six patients complained of distressing sudden awakenings with abnormal motor activity during sleep causing insomnia. Polysomnography showed paroxysmal short-lasting arousals during NREM, especially slow-wave sleep, associated with complex movements and autonomic activation. Ictal and interictal EEG never showed epileptic discharges except in 1 patient who also had a tonic-clonic seizure during sleep. Carbamazepine was the only effective medication in 2 patients. Paroxysmal arousals represent a sleep disturbance that may be related to deep epileptic foci.

Hemifacial spasm in sleep.

We conducted polygraphic studies during wakefulness and all-night sleep in 13 patients with cryptogenic and 3 with postparalytic hemifacial spasm. The movements decreased progressively with deepening sleep stages, reaching lowest values in REM sleep. The reduction was inversely related to the severity of movements during wakefulness. There was no relation between hemifacial spasm and mimic activity on the unaffected side. Central inhibitory processes may account for the partial decline in intensity of the movements in sleep.

Hypnogenic paroxysmal dystonia: epileptic seizure or a new syndrome?

Five patients between the ages of 7 and 74 years presented with nocturnal episodes characterized by coarse, often violent movements of the limbs and by a tonic phase of variable duration. Seizures recurred every night or almost every night during slow wave (NREM) sleep and were not associated with electroencephalographic (EEG) abnormalities. Interictal EEGs were normal during both sleep and wakefulness. Carbamazepine treatment was effective in all patients. Uniform clinical behavior and EEG patterns indicate a distinct nosological entity whose pathophysiology is not yet understood.

Cerebral anoxic attacks in sleep apnea syndrome.

In a 52-year-old man who presented with an obstructive sleep apnea (OSAS) syndrome, we observed cerebral anoxic attacks during rapid eye movement (REM) sleep. Polysomnography showed that the attacks were due to severe hypoxia provoked by apneas lasting up to 220 s. Electroencephalogram (EEG) and clinical features clearly differentiate cerebral anoxic attacks from epileptic seizures. The length of apneas in our patient is very unusual, indicating an impairment of the mechanism terminating apneas. The cause of this impairment is unknown. However, this case report documents a possible pathogenetic mechanism other than heart arrhythmias responsible for sudden death or coma arising during sleep.

Atrial natriuretic peptide and catecholamines in obstructive sleep apnea syndrome.

Nocturnal polyuria with repeated micturitions during the night is a clinically evident feature of obstructive sleep apnea syndrome (OSAS). These effects are reversed by continuous positive airway pressure (CPAP). There is some evidence that atrial natriuretic peptide (ANP) and catecholaminergic activity may be implicated in the pathogenesis of these symptoms. We studied these biochemical parameters in six patients with severe OSAS during two nights: the first (basal) in their normal conditions and the second during CPAP treatment. CPAP treatment reversed apnea episodes in all our patients. A significant (p less than 0.035) reduction of nocturnal urine volume (from 902 +/- 297 to 447 +/- 130 ml; mean +/- SD), sodium excretion (from 150 +/- 33 to 89 +/- 35 mEq/12 h), noradrenaline excretion (from 95 +/- 101 to 52 +/- 16 micrograms/g creatinine), noradrenaline plasma concentrations (from 325 +/- 96 to 259 +/- 75 pg/ml), ANP plasma concentrations (from 35 +/- 20 to 19 +/- 5 pg/ml) was observed during the night under CPAP application. These data suggest that in OSAS patients the high ANP plasma concentration is responsible for the observed elevated diuresis and sodium excretion. These effects are rapidly reversible, as they are reversed during the first CPAP treated night.

Unreliability of automatic scoring of MESAM 4 in assessing patients with complicated obstructive sleep apnea syndrome.

BACKGROUND: Portable devices are used for unattended recording of patients with suspected obstructive sleep apnea syndrome (OSAS). The MESAM 4 (MAP; Martinsried, Germany) is a computerized ambulatory polysomnographic system that records four parameters: breathing noise, heart rate, arterial oxygen saturation (SaO(2)), and body position. DESIGN AND METHOD: We evaluated the reliability of the oxygen desaturation index (ODI) automatically calculated by the MESAM 4 device in evaluating patients with "complicated" OSAS. These patients present SaO(2) drops due to apneas associated with a fall in baseline SaO(2) during sleep, as occurs in the "overlap syndrome." Ten patients with complicated OSAS underwent nocturnal MESAM 4 recordings, and we compared the visual and automatic scorings of the ODI. RESULTS: The ODI obtained with visual scoring was significantly higher than ODI automatically calculated by the MESAM 4 in all patients. In some patients, this difference was so significant that it could bias clinical judgment of OSAS severity. We demonstrated that the system did not identify those desaturation events that were superimposed on a fall in baseline SaO(2). The error depends on the algorithm by which the device recognizes the desaturation events and calculates the baseline SaO(2). CONCLUSION: Automatic analysis of MESAM 4 recordings may be misleading in evaluating OSAS patients who have a fall in baseline SaO(2) during sleep. In this case, visual scoring performed by a trained polysomnographer is recommended.

Sleep-related respiratory and haemodynamic changes in Shy-Drager syndrome: a case report.

The sleep-related respiratory and blood pressure changes in a patient with Shy-Drager syndrome associated with the sleep apnoea syndrome are reported. Polygraphic recordings showed repeated apnoeic episodes during both sleep and wakefulness. Systemic arterial pressure values during sleep tended to be lower than in two other patients with Shy-Drager syndrome, and, unlike observations in the sleep apnoea syndrome, nocturnal swings of arterial pressure related to obstructive apnoea were markedly reduced. As a result, the total sleep time was reduced; a sleep with several features similar to REM stage was identified; during this stage the arterial pressure reached the lowest levels recorded. A review of the literature revealed that nocturnal respiratory disturbances were detectable in a high percentage of patients with Shy-Drager syndrome. We suggest that such an association is not a chance one.

Sleep-related breathing impairment in myotonic dystrophy.

Respiratory failure has been described in myotonic dystrophy; it worsens during sleep but its central or peripheral origin has yet to be determined. Moreover, patients may present severely disturbed sleep and daytime somnolence. Eight patients with mild to moderate myotonic dystrophy were studied to assess breathing function while awake and during sleep by means of the pulmonary function tests, nocturnal polysomnographic examination and the multiple sleep latency test (MSLT). Three patients had restrictive respiratory defects; none had signs of airway obstruction. All patients had very disrupted nocturnal sleep. Of six patients who underwent the MSLT only two showed a mild tendency to sleep during the day. Six patients had pathological apnoea plus hypopnoea index [(A+H)I] and there was a prevalence of central apnoeas. The apnoeas occurred while resting but awake and throughout all sleep stages. Only two patients (the ones with the least vital capacity) had episodes of progressive oxygen desaturation during rapid eye movement sleep, similar to those found in other restrictive disorders and in chronic obstructive pulmonary disease. It is concluded that the breathing pattern characteristic of our myotonic dystrophy patients was the occurrence of central apnoeas both at rest while awake and during sleep.

Nocturnal myoclonus and restless legs syndrome.

Nocturnal myoclonus (or periodic movements in sleep) consists of stereotyped sleep-related movements of the lower limbs and occasionally also upper limbs, ranging from simple dorsiflexion of the big toe and foot to a triple flexion of the entire leg. It is characterized by a typical periodicity, often occurring in association with sleep arousal phenomena. As an isolated finding (essential nocturnal myoclonus), it represents a paraphysiological phenomenon, also found in normal subjects and developing with advancing age. On the other hand, symptomatic nocturnal myoclonus is typically associated with restless legs syndrome; in this condition, it is usually severe and present also during wakefulness. The exact site of origin of nocturnal myoclonus is unknown. It is almost certainly a subcortical phenomenon, probably modulated in its periodicity by reticular influences. It has frequently been confused with, and should be clearly differentiated from, other normal jerking movements of sleep, such as partial myoclonic jerks and massive myoclonic jerks, or sleep starts. Other abnormal movements that may be confused with nocturnal myoclonus are the startles of hyperekplexia, the syndrome of painful legs and moving toes, nocturnal leg cramps, and the numerous varieties of epileptic myoclonus.

Zolpidem-polysomnographic study of the effect of a new hypnotic drug in sleep apnea syndrome.

Clinical studies have shown that zolpidem, an original imidazopyridine derivative, induces and maintains sleep and does not have daytime side-effects. Polysomnography has revealed that this drug has several interesting qualities that benzodiazepines do not possess: stages 3-4 increase, stage 2 is unchanged or slightly reduced and no abnormal changes are detected on the EEG tracing. Like benzodiazepines, zolpidem slightly reduces REM sleep. The Multiple Sleep Latency Test confirmed that the drug does not cause daytime drowsiness. All the hypnotic drugs studied up to now worsen heavy snoring and obstructive sleep apnea syndrome. A controlled double blind cross-over trial assessed the effects of a single dose of zolpidem 20 mg on nocturnal breathing in patients with mild forms of sleep apnea syndrome. The results indicate that, at this dose, the drug does not overcome the existing contraindications to the use of hypnotics in this syndrome.

Abnormal breathing in the Rett syndrome.

Four girls affected with the Rett syndrome showed stereotyped hand movements and psychomotor regression beginning in the first or second year of life after initially normal development, with total loss of language, a severe gait, and chewing and swallowing disturbances. Breathing during active wakefulness was abnormal, with clusters of arrhythmic, tachypneic and irregular respiratory acts, intermixed with prolonged apneic episodes causing cyanosis and even fainting. On the other hand, breathing was regular during both NREM and REM sleep stages. Breathing impairment in the Rett syndrome is characterized by an inability to maintain normal respiratory patterns during wakefulness, and represents a functional disturbance of the behavioral control of breathing, which occurs during active wakefulness.

Breathing disorders in males with acquired encephalopathy.

Six boys affected by acquired encephalopathy with an abnormal breathing pattern in wakefulness were studied. Polygraphic recordings showed two different patterns in our population. In two brothers a periodic breathing pattern was recorded in the awake and sleep states. In the others, central apneas with or without tachypnea and O2 desaturation were observed only during wakefulness. The analogy of these patterns with those of genetic syndromes such as familial encephalopathy and the Rett syndrome led us to postulate the aspecificity of this finding and the importance of further studies to elucidate the role of impaired behavioural and automatic breathing system control.

Writing epilepsy.

Two patients complained of myoclonic jerks precipitated by writing. They had suffered only sporadic seizures triggered by reading. Laboratory assessment demonstrated that typing was the most powerful stimulus in triggering spike-wave discharges associated with myoclonic seizures. Sodium Valproate (20 mg/Kg/die) led to a complete remission of seizures in both cases.

Failure of automatic control of ventilation (Ondine's curse) associated with viral encephalitis of the brainstem: a clinicopathologic study of one case.

A case of Ondine's curse associated with hypothalamic dysfunction in an 8-year-old boy is described. The neuropathological examination revealed a viral encephalitis affecting the hypothalamus and the brainstem. In the medulla the inflammatory process involved the reticular formation and the nuclei considered to control automatic respiration such as the dorsal motor nucleus of the vagus, the nucleus tractus solitarii and the nucleus ambiguous. Although Ondine's curse following viral infection of the central nervous system has been previously reported this represents the first case of viral encephalitis to be pathologically documentated.