Neuroelectric assessment of HIV: EEG, ERP, and viral load.

The effects of the human immunodeficiency virus (HIV) infection on the central nervous system function were studied with electroencephalographic (EEG) and auditory event-related brain potentials (EPRs) in patients infected with HIV and unaffected young adult control subjects (n=10/group). All subjects were assessed once every 15 min for four trial blocks at the same time of day to assess EEG/ERP changes with time on task-induced fatigue. Spectral analysis was applied to the pre- and post-stimulus EEG segments. ERP values were evaluated with respect to group differences for component amplitude and latency measures. Spectral analysis demonstrated that HIV patients evinced greater pre-stimulus delta power over frontal areas compared to control subjects, and less post-stimulus spectral power for the delta, theta, and alpha bands over the central/parietal areas. P300 amplitude was smaller, and latency was marginally longer for the HIV patients compared to control subjects. P300 latency correlated positively with increases in the patient HIV viral load. Time-on-task generally did not affect EEG or ERP measures for either group other than contributing to an overall decrease in neuroelectric responsivity. Group spectral power effects were consistent with differences in arousal/fatigue level. P300 group differences were consistent with declines in cognitive capability, and P300 latency increased with increased viral load. HIV infection negatively affected central nervous system function as measured by EEG and cognitive ERPs in a manner that suggests decreased arousal and increased fatigue in HIV patients.

Effect of bedtime alcohol on inspiratory resistance and respiratory drive in snoring and nonsnoring men.

We measured inspiratory resistance (R1), inspiratory occlusion pressure (P0.1), and the ventilatory responses to hypercapnia and isocapnic hypoxia during waking and during stage 2 non-rapid eye movement sleep in nine young men who were habitual snorers. They were studied on 2 nights during the 3 hours after receiving a bedtime drink containing either a placebo or 100-proof vodka (1.5 ml/kg) in orange juice. We compared the results with those we reported previously in 10 nonsnoring but otherwise similar men. Waking R1 was the same in nonsnorers and snorers, and it was not affected by ethanol. During sleep on the control night, R1 increased by 70% in nonsnorers and by 280% in snorers. On the ethanol night, the increase from waking to sleeping was more than doubled in both nonsnorers and snorers. P0.1 and the responses to hypercapnia and hypoxia showed no differences between nonsnorers and snorers, therefore the results from the two groups were pooled. Minute ventilation and the hypercapnic response decreased from waking to sleeping and P0.1 was more negative during sleep, but there was no significant effect of ethanol. There was a significant correlation between the changes from waking to sleeping in R1 and P0.1 on the ethanol night suggesting that inspiratory effort increased in response to the increased resistance. The response to isocapnic hypoxia showed no effect of either sleep state or drink. Inspiratory time did not change but mean inspiratory flow (VT/T1) was significantly reduced during sleep on both control and ethanol nights. The duty cycle ratio (T1/Ttot) was significantly increased during sleep on the ethanol night. Despite its great effect on inspiratory resistance, especially in snorers, ethanol, in the dose used in our study, does not augment the depression of minute ventilation or of the hypercapnic response that occur normally in stage 2 non-rapid eye movement sleep. After ethanol, our subjects showed the decreased VT/T1 and the increased T1/Ttot that occur normally during sleep in response to an inspiratory resistive load. However, they also showed increased inspiratory effort. The combination of increased inspiratory resistance and greater inspiratory effort would increase the tendency of an unstable upper airway to collapse and could account for the aggravation of obstructive sleep apnea by ethanol.

Identification and treatment of sleep problems in the elderly.

For many adults, changes in sleep occur with aging. An estimated 15 million elderly, or 50% of older Americans, experience some sleep problem. The elderly complain that their sleep is more fragmented and that as they have gotten older, they experience more daytime sleepiness. Laboratory studies have confirmed these complaints. Research has shown that it is not the need for sleep that decreases with age, but rather the ability to sleep. Circadian rhythm disturbances, sleep disorders such as sleep disordered breathing and periodic movements in sleep, medical illness, medication use, and impaired cognitive functioning all contribute to poor sleep and decreased daytime alertness. In institutionalized elderly, sleep is even more disturbed and disrupted. With careful assessment, many of these problems can be addressed and treated, and sometimes cured.

Self-reported snoring in pregnancy. Association with fetal outcome.

OBJECTIVES: To determine the incidence of self-reported snoring in pregnant compared with nonpregnant women. To compare indicators of fetal outcome in pregnant women with self-reported frequent snoring vs those without snoring. STUDY DESIGN: Prospective, nonrandomized screening and comparison between groups. PATIENTS: Three hundred fifty pregnant women and 110 age-matched nonpregnant women. METHODS: Survey evaluating self-reported snoring. For the pregnant women, infant birthweight, APGAR scores, and other indicators of fetal outcome were obtained by record review. RESULTS: Frequent snoring was reported in 14% of the pregnant women vs 4% of the nonpregnant women (Chi2=6.2; df=1; p<0.05). The pregnant women who reported frequent snoring did not have deliveries resulting in infants with evidence of an increase in compromised outcomes. CONCLUSIONS: Frequent snoring is reported more often in pregnant than in nonpregnant women. Snoring mothers do not appear to be at increased risk for delivering infants with fetal compromise as might be expected with the concomitant occurrence of obstructive sleep apnea.

Identification and treatment of sleep apnea in patients with chronic headache.

This study investigates the relationship between nocturnal or morning headache and obstructive sleep apnea syndrome (sleep apnea). It is not known if headache of any type is more common in patients with sleep apnea than in other patients, but morning headache is a symptom of sleep apnea. A method is needed for identifying patients with chronic headache who might benefit from evaluation and treatment of sleep apnea. We performed a retrospective assessment of frequency of morning headache in patients grouped according to final diagnosis: sleep apnea (n = 72), periodic leg movements of sleep (n = 28), and psychophysiologic insomnia (n = 42). Prospective overnight sleep studies were obtained in a different group of 19 patients who presented for evaluation of headache. We selected certain patient characteristics as possibly indicative of sleep apnea-related headache. The retrospective study showed that 24% of patients with sleep apnea had frequent morning headache, which was not different from the other groups. In the separate group of 19 patients with chronic headache and suspected sleep disorder, 17 had sleep apnea. Nasal continuous positive airway pressure was prescribed to 14 patients. Marked improvement in headache occurred and persisted in 4 patients and moderate improvement in 3. Responders to therapy were more likely to have vascular headaches than mixed or tension headaches, more severe sleep apnea, and a nocturnal or morning timing to their headaches. However, there was large overlap in severity of sleep apnea and likelihood of response. We conclude that morning headache is not more common in sleep apnea than in other sleep disorders. However, over 30% of patients with chronic headache and other symptoms of sleep apnea have significant improvement in headache after treatment of sleep apnea.

Maintenance of wakefulness test in obstructive sleep apnea syndrome.

The usefulness of a 40-min per trial version of the maintenance of wakefulness test was assessed in 322 patients with obstructive sleep apnea. This test is a variant of the multiple sleep latency test in which patients are asked to remain awake in a quiet darkened room, and then monitored for electroencephalographic sleep onset. The four trials of the test are each stopped after 40 min. The mean sleep latency for all patients was 26.0 +/- 11.8 (SD) min. In a group of 24 patients who underwent treatment with nasal continuous positive airway pressure, the mean sleep latency increased from 18.0 +/- 12.3 to 31.9 +/- 10.4. The strongest nocturnal correlates of the MWT sleep latency were respiratory arousal index (r = -.35), mean oxygen saturation (r = .30), and weight/height ratio (r = -.25). These correlations were comparable to other studies using the MSLT. There were strong intercorrelations among the variables. In the more severe groups, measures of hypoxemia were more strongly correlated with MWT sleep latency. A two-factor analysis of variance using respiratory arousal index and several measures of oxyhemoglobin saturation indicated that both arousals from sleep and degree of hypoxemia contribute interactively to daytime dysfunction in patients with sleep apnea. The MWT appears useful in evaluating disability from daytime sleepiness.

Sleep in Alzheimer's disease and other dementing disorders.

It is estimated that up to 10% of the elderly population have clinically significant cognitive deficits. The neuronal pathologies that underlie the dementing disorders cause both cognitive dysfunction and disturbances in normal sleep/wake patterns. Here we report the changes in sleep/wake patterns seen with increasing severity of Alzheimer's disease, probably the most common dementing disorder. In addition, studies examining sleep/wake patterns in a number of other dementing disorders are reviewed.

Ondine curse and neurocristopathy.

Two newborns, 1 male and 1 female, had both Ondine curse, also known as congenital, central hypoventilation syndrome, and Hirschsprung disease. Both infants demonstrated insufficient respiration while asleep and normal respiration when awake. The lesser affected child had an otherwise normal neurologic examination, but suffered from seizures. He died at 18 months of age; neuropathologic examination of the brain was unremarkable. The girl had a severe and ultimately fatal form of this disorder and manifested a variety of neurologic abnormalities indicative of developmental failure of the neural crest-derived tissues. These abnormalities included unreactive pupils and deafness. She died at 40 days of age; autopsy permission was denied. The etiology of sleep apnea is not known. Mechanisms of central integration may be abnormal but the association with neural crest maldevelopment implicates the peripheral nervous system.

Stereotaxic placement of cannulae in cerebral ventricles of the pig.

We have developed and employed a stereotaxic coordinate system for the pig brain based on eternal skull landmarks. Sagittal, coronal, and horizontal planes were defined. Based on histological maps and ventricular casts, the coordinates for locating the lateral ventricles were described. Guide tubes leading to the lateral ventricles have been chronically implanted. This access route to the ventricular system has been used for stimulation of the dipsogenic response with angiotensin and for withdrawal of cerebrospinal fluid. Solved and unsolved problems arising with these procedures have been defined.