[Visual, auditory and somatosensory potentials in the diagnosis of vitamin B12 deficiency]. / Apport des potentiels évoqués visuels, auditifs et somesthésiques dans le diagnostic d'une carence en vitamine B12.

We describe visual, brain stem auditory, and somatosensory evoked (VEP, BAEP, SEP) in a 49-year old male patient presenting with subacute degeneration of the spinal cord due to vitamin B12 deficiency. Neurological signs included tetraplegia with a C4-C5 spinal cord compression that was unchanged after surgical decompression. Before treatment, the duration of the bilateral VEP was slightly increased, though their amplitude and morphology were not modified. BAEP were normal. However, abnormalities of SEP with loss of cortical potentials were noticed. Two months after initiation of the treatment, both VEP and SEP recorded in response to median nerve stimulation had improved, but there was still no cortical response to tibial nerve stimulation. Eighteen months later, VEP were normal and recovery of SEP in response to tibial nerve stimulation was observed; however, alterations of peripheral sensory and motor action potentials were still present. These findings are in good agreement with previously reported pathological changes in patients presenting with subacute combined degeneration. Similar abnormalities have been described in patients with multiple sclerosis. Evoked potentials in this case proved to be useful for the diagnosis and the evaluation of the efficacy of the treatment. These findings also suggest that demyelination of the posterior part of the spinal cord and peripheral axonal degeneration might be the main pathological changes related to vitamin B12 deficiency. The former, but not like the latter, were clearly responsive to the treatment.

Relationship between maximal oxygen uptake on different ergometers, lean arm volume and strength in paraplegic subjects.

The present experiment was designed to study the importance of strength and muscle mass as factors limiting maximal oxygen uptake (VO2max) in wheelchair subjects. Thirteen paraplegic subjects [mean age 29.8 (8.7) years] were studied during continuous incremental exercises until exhaustion on an arm-cranking ergometer (AC), a wheelchair ergometer (WE) and motor-driven treadmill (TM). Lean arm volume (LAV) was estimated using an anthropometric method based upon the measurement of various circumferences of the arm and forearm. Maximal strength (MVF) was measured while pushing on the rim of the wheelchair for three positions of the hand on the rim (-30 degrees, 0 degrees and +30 degrees). The results indicate that paraplegic subjects reached a similar VO2max [1.23 (0.34) 1 x min(-1), 1.25 (0.38) 1 x min(-1), 1.22 (0.18) 1 x min(-1) for AC, TM and WE, respectively] and VO2max/body mass [19.7 (5.2) ml x min(-1) x kg(-1), 19.5 (6.14) ml x min(-1) x kg(-1), 19.18 (4.27) ml x min(-1) x kg(-1) for AC, TM and WE, respectively on the three ergometers. Maximal heart rate f((c) (max)) during the last minute of AC (173 (17) beats x min(-1)], TM [168 (14) beats x min(-1)], and WE [165 (16) beats x min(-1)], were correlated, but f((c) (max)) was significantly higher for AC than for TM (P < 0.03). There were significant correlations between MVF and LAV (P < 0.001) and between the MVF data obtained at different angles of the hand on the rim [311.9 (90.1) N, 313.2 (81.2) N, 257.1 (71) N, at -30 degrees, 0 degrees and +30 degrees, respectively]. There was no correlation between VO2max and LAV or MVF. The relatively low values of f((c) (max)) suggest that VO2max was, at least in part, limited by local aerobic factors instead of central cardiovascular factors. On the other hand, the lack of a significant correlation between VO2max and MVF or muscle mass was not in favour of muscle strength being the main factor limiting VO2max in our subjects.

Rapid shift in peak melatonin secretion associated with improved performance in short shift work schedule.

We studied the performance and adaptability of 40 nurses (median age 35 years), 20 on permanent day shift and 20 on permanent night shift with fast rotation of work and days off, matched for age, gender, and socio-familial responsibilities. For 15 days prior to the study, subjects maintained sleep logs and trained for performance tests. Questionnaires were administered to evaluate adaptability to shift work. During the experimental phase, sleep/wake patterns were monitored using sleep logs and activity/inactivity with wrist actigraphy. Performance levels were measured with the four choice reaction time and memory test for seven letters, eight times/day during the wake period, days on and off. On the last day of work and first day off, 6-sulfatoxy-melatonin levels were assayed from urine samples collected every 2 hours. Estimated total sleep time during the 15-day experimental period was not significantly different in the dayshift and nightshift nurses. Night nurses shifted regularly to daytime activities on days off and, as a group, were significantly sleep deprived on work days with napping on the job in 9 of the 20 night shift nurses (mean of 114+/-45 minutes per shift) and a significant performance decrement during the work period. Further analysis revealed two subgroups of night nurses: The majority (14 nurses) had a mean peak of 6-sulfatoxy-melatonin at 0718 hours on days off and no peak during night work while the other 6 night shift nurses presented a fast melatonin shift with two clear peaks on both work and days off. Comparison of performance scores revealed that all nurses performed similarly on days off. Daytime nurses and fast-shifting night nurses had similar scores on work days, while nonshifting night nurses had significantly lower scores at work. Despite similar gender, age, social conditions, and light exposure levels, a minority of the nurses studied possessed the physiological ability to adapt to a fast-shifting sleep-wake schedule of more than 8 hours and were able to perform appropriately in both conditions. This shift was associated with a change in the acrophase of 6-sulfatoxy-melatonin.

Long-term effects of nasal intermittent positive-pressure ventilation on pulmonary function and sleep architecture in patients with neuromuscular diseases.

STUDY OBJECTIVE: This article evaluates the long-term clinical and physiologic effects of nocturnal nasal intermittent positive-pressure ventilation (NIPPV) in patients with neuromuscular disease. METHODS: Before and after 18 +/- 2 months of NIPPV, we measured during the daytime arterial blood gases, lung mechanics, and respiratory muscle strength in 8 patients (51 +/- 5 years; mean +/- SEM). Sleep parameters were also evaluated at 10 +/- 2 months. RESULTS: All patients tolerated NIPPV and none required hospitalization during follow-up. After NIPPV, daytime arterial PO2 increased (71 +/- 4 to 81 +/- 2 mm Hg; p < 0.05) and arterial PCO2 decreased (46 +/- 3 to 41 +/- 1 mm Hg; p < 0.05). The change of PaO2 after NIPPV was related to its baseline value (r2 = 0.78, p < 0.05). Vital capacity (50 +/- 6% predicted), total lung capacity (63 +/- 4% predicted), alveolar-arterial oxygen gradient (20 +/- 3 mm Hg), and maximal inspiratory (39 +/- 9% predicted) or expiratory (32 +/- 5% predicted) pressures did not change after NIPPV. The apnea-hypopnea index fell from 22 +/- 6 to 1 +/- 1 (p < 0.05), and both sleep architecture and sleep efficiency (from 59 +/- 8% to 83 +/- 5%; p < 0.05) were enhanced. The time spent with an arterial oxygen saturation (SaO2) value below 90% decreased from 160 +/- 53 min to 8 +/- 4 min (p < 0.05). Mean (88 +/- 3 to 95 +/- 1%; p < 0.05) and minimal nocturnal SaO2 (67 +/- 5 to 89 +/- 1%; p < 0.001) improved after NIPPV. CONCLUSIONS: In patients with neuromuscular disease, long-term NIPPV is well tolerated and easy to implement clinically. In these patients, long-term NIPPV improves daytime arterial blood gas values and sleep-disordered breathing. However, it does not modify lung mechanics or respiratory muscle strength.

Rapid shift in sleep time and acrophase of melatonin secretion in short shift work schedule.

Tolerance to shift work and adaptability to shifting schedules is an issue of growing importance in industrialized society. We studied 40 registered nurses, 20 on fixed day-shifts and 20 on fixed night-shifts, to assess whether workers with rapidly shifting schedules were able to adapt their melatonin secretion and sleep-wake cycles. The day-shift worked 5 days with 2 days off and the night-shift worked 3 nights with 2 off. All night-shift personnel acknowledged shifting back to daytime schedules on their days off. Sleep-wake was determined by sleep logs and actigraphy. To measure 6-sulfatoxymelatonin levels, urine was collected at 2-hour intervals on the last work day and on the last day off. Night-shift workers slept significantly more on days off. Napping on the job occurred in 9/20 night-shift workers (mean 114 minutes) between 3 and 6 a.m. The acrophase of 6-sulfatoxymelatonin in day-shift nurses occurred at similar times on workdays and off days. In night-shift nurses, the acrophase was about 7 a.m. on days off, but had a random distribution on workdays. Further analysis revealed two subgroups of night-shift nurses: six subjects (group A).demonstrated a rapid shift in melatonin secretion (acrophase at near 12 noon on work days and at near 7 a.m. on days off) while 14 nurses (group B) did not shift. Group A nurses slept more in the daytime on work days and their total sleep time was the same as day-shift nurses. Group A was slightly younger and was composed solely of women (there were nine women and five men in group B). Age may be a factor in the ability to adapt to rapidly shifting schedules.

Sleep-related respiratory disturbances in patients with Duchenne muscular dystrophy.

Sleep-related respiratory disturbances (SRD) in patients with muscle diseases may have significant clinical implications, because the patients frequently die at night. The aims of the study were to :1) assess the presence and severity of sleep-related respiratory disturbances in patients with Duchenne muscular distrophy (DMD); and 2) investigate the relationship of sleep-related respiratory disturbances to daytime symptoms and pulmonary function. We studied six clinically stable patients with Duchenne muscular dystrophy, mean age (+/- SD) 18 +/- 2 yrs. Vital capacity was 27 +/- 19% of predicted and daytime arterial oxygen tension (PaO2) was 10.9 +/- 1 kPa (range 8.9-12.4 kPa). The presence of daytime somnolence, insomnia, headache, nightmares and/or snoring was recorded. Four patients (67%) showed symptoms that suggest sleep-related respiratory disturbances. At night, the apnoea-hypopnoea index (AHI) was 11 +/- 6. The patients with more symptoms during the daytime had the highest AHI scores. Most of the apnoeas (85%) were central, particularly during rapid eye movement (REM) sleep. Sleep architecture was well-preserved. Arterial desaturation (> 5% below baseline) occurred during 25 +/- 23% of total time. AHI correlated with daytime PaO2, and AHI in REM sleep correlated with age. A stepwise multivariate analysis showed that PaO2 and, to some extent, the degree of airflow obstruction were significantly correlated with AHI. We conclude that sleep-related respiratory disturbance are frequently present in patients with Duchenne muscular dystrophy. Therefore, physicians should look for symptoms related to sleep-related respiratory disturbances in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[Value of somatosensory evoked potentials in spinal surgery monitoring in children and adolescents: 110 cases]. / Intérêt des potentiels évoqués somesthésiques dans la surveillance de la chirurgie du rachis chez l'enfant et l'adolescent: à propos de 110 cas.

This study shows the results obtained in 110 patients, children and adolescents by monitoring somatosensory evoked potentials during spinal surgery: Cotrel-Dubousset instrumention, surgical anterior correction by plating, spondylolisthesis and hemivertebra surgery. The recordings were made in preoperative, peroperative and postoperative period; the anaesthetic and electrophysiological conditions allowed us to obtain reliable recordings. In the peroperative period, the recordings were made: after induction of anesthesia and exposure of the spine, after instrumentation, after maximum traction and at the end of the operation. Analysis of the peroperative somatosensory evoked potentials (PESEP) showed significant differences in latencies, but also in amplitudes and morphology during distraction in scoliosis or spondylolisthesis. These impairments gradually improved and recovered their normal values at the end of the operation. The impairments were, with equal correction, 4 times more important in Cotrel-Dubousset instrumentation than in surgical anterior correction by plating. During instrumentation and in two cases, the impairments observed led the surgeon to change his operative behavior, certainly avoiding a postoperative neurological disorder, the "wake-up test" was made in one case. The correlation between the neurological problems, and the impairments of the potentials allowed us to define alarm criteria, and if they persist the "wake-up test" becomes necessary.

Breathing disorders during sleep in myasthenia gravis.

Twenty consecutive patients (16 women and 4 men), with a mean age of 40 years, who were diagnosed and treated for myasthenia gravis were enrolled in a prospective investigation aimed at determining the amount of respiratory disturbance occurring during sleep while they received treatment. Patients were clinically evaluated to determine body mass index, presence of upper airway anatomical abnormalities, level of functional capacity and activity scored from 1 to 5, and presence of sleep-related complaints. They underwent daytime pulmonary function tests, determination of maximal static inspiratory pressure, measurement of transdiaphragmatic pressure, and measurement of arterial blood gas levels. Polygraphic monitoring during sleep, evaluating respiration and oxygen saturation, was also performed. Results indicated that in the studied population, all subjects had evidence of daytime diaphragmatic weakness as demonstrated by transdiaphragmatic pressure measurements, independent of the degree of autonomy and functional capacity and activity level reached. Older patients with moderately increased body mass index, abnormal total lung capacity, and abnormal daytime blood gas concentrations were the primary candidates for development of diaphragmatic sleep apneas and hypopneas, and oxygen desaturation of less than 90% during sleep. However, these clear indicators were not found in all subjects with sleep-related disordered breathing. Rapid-eye-movement sleep was the time of highest breathing vulnerability during sleep. Sleep-related complaints may also help identify subjects at risk for abnormal breathing during sleep, even when daytime functional activity is judged normal.

[Contribution of somatosensory evoked potentials in the surveillance of the spinal cord during spinal surgery]. / Apports des potentiels évoqués somesthésiques dans la surveillance médullaire au cours de la chirurgie rachidienne.

This study shows the results obtained in 51 patients, children and adolescents by monitoring somatosensory evoked potentials during spinal surgery: Cotrel-Dubousset instrumentation, surgical anterior correction by plating, spondylolisthesis and hemivertebra surgery. The recordings were made in preoperative, peroperative and postoperative periods; the electro-physiological and anaesthetic conditions allowed us to obtain reliable recordings. Analysis of the peroperative somatosensory evoked potentials showed significant differences in latencies, but also in amplitudes and morphology during distraction in scoliosis or spondylolisthesis. These impairments gradually improved and recovered their normal values at the end of the operation. The impairments were, with equal correction, 4 times more important in Cotrel-Dubousset instrumentation than in surgical anterior correction by plating. In 3 cases, the modifications observed during instrumentation led the surgeon to change his operative behavior avoiding certainly a postoperative neurological disorder. The correlation between the neurological troubles and the impairments of the potentials allowed us to define alarm criteria, and if they persist the wake-test becomes necessary.

Adult maltase acid deficiency myopathy: treatment with long-term home mechanical ventilation.

We report a study of an adult with a maltase acid deficiency myopathy. A restrictive respiratory syndrome due to respiratory muscle weakness is associated with paralysis of other muscular groups. In 1982 the patient presented with an alveolar hypoventilation, and mechanical ventilation was required after acute respiratory failure. The patient has received nocturnal mechanical ventilation by tracheostomy at home for 5 years. His clinical status gradually improved in parallel to amelioration of his respiratory condition. Functional respiratory tests improved: initial hypoxia-hypercapnia disappeared, vital capacity increased. The possible mechanisms underlying the improvement are discussed. Increase in pulmonary compliance is an argument to explain the functional improvement observed. Ventilatory response to carbon dioxide was abnormal whereas the ventilatory response to exercise and maxima minute ventilation test were normal. Results are consistent with a respiratory control impairment. The role of mechanical ventilation is difficult to assess in the improvement we observed.

Lung transfer factor for CO at rest in normal children by a steady-state method.

Lung transfer for CO (TLCO) was measured at rest in 94 normal children (47 boys and 47 girls) whose ages ranged from 3.5 to 16 years. A steady-state method, using a technique of alveolar sampling based on the equality of the mean expiratory and alveolar respiratory quotients, was employed. Highly significant correlations, statistically different for boys and girls, were fond between TLCO and standing height. TLCO was also linearly correlated with the functional residual capacity--the only pulmonary volume measurable in very young children--but without any sex difference. A multiple linear regression relates TLCO to FRC and height. Variance analysis shows the preponderant influence of FRC.

[Routine bedside measurement of arterio-alveolar CO2 difference (author's transl)]. / Mesure de la différernce artério-alvéolaire en CO2 en routine au lit du malade.

Deficiencies in pulmonary circulation can economically be demonstrated at the patient's bedside by measuring the difference in CO2 between arterial blood and alveolar air, which reflects the air flow in non-perfused ventilated lung areas. The method does not inform on the cause of the deficiency, but normal values (i.e. lower than 10 %) indicate that pulmonary circulation is unimpaired, whereas high values suggest that it is reduced (emboli, capillary obstruction by leukocytes). That the method is valid is shown by the parallelism observed between the percentage air flow in non-perfused ventilated areas and the angiographic and anatomical findings.

[Interest of helium-oxygen flow volume and isoflow volume curves in chronic obstructive lung disease (author's transl)]. / Intérêt des courbes débit-volume en air et en mélange hélium-oxygène dans les bronchopathies chroniques obstructives.

We have compared changes in maximal flows induced by breathing gases of different density in 54 patients suffering from emphysema and chronic bronchitis. We considered as positive responders those subjects displaying an increase by at least 20% of maximal expiratory flows while breathing gases of lower density. Such a response was demonstrated in 21 cases, the remainder (33 cases) being non-responders. Hence, in such patients, airways obstruction may primarily be localised in central or peripheral airways. There was no correlation between the nature of this response and the clinical diagnosis, but non-responders, in general, were those in whom respiratory insufficiency was more severe. There seemed to be no additional information gained by measuring isoflow-volume (iso V vol.) in comparison with measuring differences in maximal flows at 50% of vital capacity.

[Study upon oxygen conveyance in severe anaemia. About a very serious case of hemolytic anaemia which led to a myocardial infarct (author's transl]. / Transport de l'oxygène lors des anémies sévères. Une observation d'anémie hémolytique grave compliquée d'infarctus du myocarde.

To understand the orientation the metabolism of a sick person whose arterial content in oxygen had collapsed (CaO2 reaching 1,9 vol/100 ml) the cardiac output and the rate myocardic extraction of the lactates have been measured. The cardiac index was very high 7,4 l/m/m2 and in spite of a low D (a-v) (2,5 vol/ml) the consumption of oxygen was normal. Three days after a first measure the steep (or brutal) fall of the cardiac and the reversal of the rate of myocardic extraction of lactate led up to diagnose an acute coronary insufficiency. The electrocardiogramm only cortoborated the myocardic necrosis in a second time. This result invites (or calls for) a constant electrographic watching of sick persons who suffer from severe anaemia, even with sane coronary vessels, to avoid diagnosing coronary insufficiency through so circuitous means.

[Study of pulmonary leucostasis by measurement of the alveolo-arterial CO2 difference (author's transl)]. / Etude de la leucostase pulmonaire par mesure de la différence artério-alvéolaire en CO2.

In order to study pulmonary leucostasis in 18 leukemic subjects, the ventilatory flow from ventilated nonperfused zones (VFVNZ) was measured using alveolo-arterial CO2 difference (28 times). This method proved to be simple and accurate in the follow-up of the patients. The number of white cells necessary to increase the VFVNZ by 1% is very different from one histologic type to another. These results are in agreement with in vitro observations.

[Arterio-alveolar difference in CO2 (AaDCO2) : measurement, interpretation, clinical value]. / Différence artério-alvéolaire en CO2 (DaAco2) : mesure, interprétation, intérêt clinique.

The measurement of arterio-alveolar difference in CO2, easily performed, gives the percentage of non perfused ventilated pulmonary zones. The clinical value of this examination is illustrated by two observations. Its situation, among other tests of the respiratory function, is questioned particularly when the diagnosis of pulmonary embolism is concerned.