E. Sforza

Sleep-wake cycle abnormalities in fatal familial insomnia. Evidence of the role of the thalamus in sleep regulation

Alterations in sleep organization were longitudinally studied in 6 new cases of fatal familial insomnia (FFI) by 24 h polygraphic recording. All patients showed an early reduction in sleep spindles and K complexes, and a drastic reduction in total sleep time and disruption of the cyclic sleep organization. Complete abolition of NREM sleep and persistence of only brief residual periods of REM sleep without atonia were features characteristic of the 3 patients with a short (less than 1 year) clinical course, and lacking in the 3 cases with a longer (more than 2 years) disease course. In the latter, sudden transitions from waking to NREM or REM sleep occurred, sometimes recurring periodically. Our findings confirm that impairment of sleep-wake regulation is a consistent distinctive feature of FFI.

Cardiovascular autonomic dysfunction in normotensive awake subjects with obstructive sleep apnoea syndrome

Cardiovascular autonomic function in normotensive awake patients with obstructive sleep apnoea syndrome was studied in 21 normotensive (mean age 48 ± 14 years), drug-free men with obstructive sleep apnoea syndrome. Cardiovascular reflex tests with continuous blood pressure monitoring and biochemical indices were performed the morning after a standard polygraphic sleep recording. A group of 20 agematched (mean age 49 ± 19 years) normal subjects was used as controls. The obstructive sleep apnoea syndrome patients showed higher heart rate and noradrenaline plasma levels (p < 0.05) at rest and a higher blood pressure response to head-up tilt (p < 0.01), suggesting sympathetic overactivity. Respiratory arrhythmia, baroreflex sensitivity index and Valsalva ratio were significantly lower in the obstructive sleep apnoea syndrome group (p < 0.01) whereas the decrease in heart rate induced by the cold face test was significantly higher (p < 0.05) showing a blunting of reflexes dependent on baroreceptor or pulmonary afferents with normal or increased cardiac vagal efferent activity. These abnormalities in autonomic regulation may predispose obstructive sleep apnoea syndrome patients to cardiovascular complications like hypertension and cardiac arrhythmias.

Paroxysmal periodic motor attacks during sleep: clinical and polygraphic features

Three patients complained of paroxysmal motor attacks during sleep. Videopolygraphic recordings showed that motor activity could be divided into events of increasing behavioural complexity. Simpler motor events often represented the initial fragment of more complex attacks. Clinical features suggested the attacks represented frontal lobe epileptic seizures. The attacks recurred during NREM sleep with a periodic repetition every 20-60 sec. This periodicity could be related to the analogous physiological oscillation during light sleep and the periodicity of K complexes, exerting a facilitating influence upon epileptic mechanisms.

Validation of Symptoms Related to Excessive Daytime Sleepiness

The aim of this study was to validate some recurring definitions of excessive daytime sleepiness (EDS) obtained from descriptive epidemiological studies. We devised questions concerning concepts such as ‘tiredness’, ‘resistible sleepiness’, ‘irresistible sleepiness’ and ‘sudden sleep attacks’. The validation was done by comparing the answers with the results of the Multiple Sleep Latency Test (MSLT), considered the gold standard, or criterion measure, for the diagnosis of EDS. The sample study comprised 73 subjects, 57 outpatients referred to our Sleep Center complaining of daytime sleepiness, snoring or sleep apnea and 16 inpatients admitted to our Neurological Institute for causes other than sleep disorders. A moderate correlation (p = –0.38, 95% confidence interval –0.57 to –0.19) was found between ‘irresistible sleepiness’ and mean sleep latency (MSL). The best combinations of sensitivity and specificity in identifying EDS, for 5- and 8-min MSL cutoffs, were observed for the questions concerning ‘sudden sleep attacks’ and ‘irresistible sleepiness’ (areas under the receiver-operating characteristic curves = 66 and 67%, respectively). The subitems exploring the frequency and situations of occurrence of these symptoms improved the validity in identifying EDS. The items regarding ‘tiredness’ and ‘resistible sleepiness’ were not related to the results of the MSLT. In subgroup analysis, irresistible sleepiness failed to identify pathologic MSLT in sleep-disordered breathing subjects. According to previous observations, we suggest that the concept of sleepiness includes various domains heterogeneously related with MSL and that questionnaires must be tailored to the different populations studied.

Sleep and cranial dystonia

A nocturnal polygraphic study was performed on 10 patients with cranial dystonia (blepharospasm (BS) and oromandibular dystonia (OMD)). All patients showed impaired sleep efficiency and reduced slow and REM sleep, more marked in subjects with severe dystonia. Abnormal muscular activity decreased progressively with deeper sleep and during the first hours of the night, without disappearing. A disordered hypnic++ pattern and impaired motor control even during sleep are typical features in cranial dystonia.

Plasma endogenous benzodiazepine-like activity in sleep disorders with excessive daytime sleepiness

Endozepines are nonhalogenated, benzodiazepine-like, nonpeptide allosteric modulators of the GABAA receptor that mimic the pharmacologic activity of exogenous benzodiazepines and are present in physiologically significant amounts in the brain. [1,2] Increased endozepine-4 activity is present in idiopathic recurring stupor (IRS), a condition characterized by bouts of stupor and coma reversed by flumazenil, a benzodiazepine antagonist. [3-5] Endozepines could thus have a role in altered mental states characterized by impaired vigilance. Narcolepsy and obstructive sleep apnea syndrome (OSAS) are sleep disorders with excessive daytime somnolence. There are no studies of endozepine activity in these clinical conditions. We studied 11 drug-free patients with narcolepsy (mean age, 35.9 plus minus 16 years) and nine patients with OSAS (mean age, 51.8 plus minus 11 …

Isolated failure of noradrenergic transmission in a case with orthostatic hypotension and hyperactivity of gastro-colic reflex

We describe a 37-year-old man with a long-standing history of impotence and urgency of defaecation. The latter invariably followed the ingestion of food. Studies of cardiovascular autonomic function disclosed asymptomatic orthostatic hypotension due to isolated sympathetic noradrenergic failure with intact cardiac vagal control. There were no other neurological abnormalities. Levels of plasma noradrenaline and urinary vanillylmandelic acid were very low but plasma dopamine and urinary homovanillic acid were normal. A low level of dopamine-beta-hydroxylase activity was detected in plasma. The patients parents were first cousins. The parents, the brother and the sister were investigated and clinical and biochemical studies showed no abnormalities.We conclude that this is a further observation of orthostatic hypotension due to isolated adrenergic failure with clinical and biochemical features different from cases previously described.

Contents Vol. 20, 2001

M.Z. Al Kawi, Riyadh A. Alpérovitch, Paris D.W. Anderson, Bethesda, Md. E. Beghi, Milano M.M. Ben Hamida, Tunis F. Bermejo, Madrid N.E. Bharucha, Bombay G. Boysen, Copenhagen M.M.B. Breteler, Rotterdam R. D’Alessandro, Bologna J.F. Dartigues, Bordeaux G.M. Franklin, Seattle, Wash. G. Friday, Wynnewood, Pa. R. Hart, San Antonio, Tex. W.A. Hauser, New York, N.Y. C. Ketzoian, Montevideo S.J. Kittner, Baltimore, Md. W.C. Koller, Miami, Fla. A. Korczyn, Tel Aviv J.F. Kurtzke, Washington, D.C. S.-M. Lai, Kansas City, Kans. J. Matias-Guiu, Alicante R.P. Mayeux, New York, N.Y. K. Nakashima, Yonago K. Nelson, Bethesda, Md. L. Nelson, Stanford, Calif. A.H. Rajput, Saskatoon D. Rosselli, Bogotá D. Royall, San Antonio, Tex. R.L. Sacco, New York, N.Y. I. Skoog, Göteborg C. Tanner, Sunnyvale, Calif. X. Zhang, Beijing Editor-in-Chief

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.