Pilot Study of Propofol-induced Slow Waves as a Pharmacologic Test for Brain Dysfunction after Brain Injury.

BACKGROUND: Slow waves (less than 1 Hz) are the most important electroencephalogram signatures of nonrapid eye movement sleep. While considered to have a substantial importance in, for example, providing conditions for single-cell rest and preventing long-term neural damage, a disturbance in this neurophysiologic phenomenon is a potential indicator of brain dysfunction. METHODS: Since, in healthy individuals, slow waves can be induced with anesthetics, the authors tested the possible association between hypoxic brain injury and slow-wave activity in comatose postcardiac arrest patients (n = 10) using controlled propofol exposure. The slow-wave activity was determined by calculating the low-frequency (less than 1 Hz) power of the electroencephalograms recorded approximately 48 h after cardiac arrest. To define the association between the slow waves and the potential brain injury, the patients' neurologic recovery was then followed up for 6 months. RESULTS: In the patients with good neurologic outcome (n = 6), the low-frequency power of electroencephalogram representing the slow-wave activity was found to substantially increase (mean ± SD, 190 ± 83%) due to the administration of propofol. By contrast, the patients with poor neurologic outcome (n = 4) were unable to generate propofol-induced slow waves. CONCLUSIONS: In this experimental pilot study, the comatose postcardiac arrest patients with poor neurologic outcome were unable to generate normal propofol-induced electroencephalographic slow-wave activity 48 h after cardiac arrest. The finding might offer potential for developing a pharmacologic test for prognostication of brain injury by measuring the electroencephalographic response to propofol.

Using Hilbert-Huang Transform to assess EEG slow wave activity during anesthesia in post-cardiac arrest patients.

Hypoxic ischemic encephalopathy (HIE) is a severe consequence of cardiac arrest (CA) representing a substantial diagnostic challenge. We have recently designed a novel method for the assessment of HIE after CA. The method is based on estimating the severity of the brain injury by analyzing changes in the electroencephalogram (EEG) slow wave activity while the patient is exposed to an anesthetic drug propofol in a controlled manner. In this paper, Hilbert-Huang Transform (HHT) was used to analyze EEG slow wave activity during anesthesia in ten post-CA patients. The recordings were made in the intensive care unit 36-48 hours after the CA in an experiment, during which the propofol infusion rate was incrementally decreased to determine the drug-induced changes in the EEG at different anesthetic levels. HHT was shown to successfully capture the changes in the slow wave activity to the behavior of intrinsic mode functions (IMFs). While, in patients with good neurological outcome defined after a six-month control period, propofol induced a significant increase in the amplitude of IMFs representing the slow wave activity, the patients with poor neurological outcome were unable to produce such a response. Consequently, the proposed method offer substantial prognostic potential by providing a novel approach for early estimation of HIE after CA.

The influence of a mandibular advancement plate on polysomnography in different grades of obstructive sleep apnea.

OBJECTIVES: The purpose of this study was to investigate the effect of a mandibular advancement device on different grades of obstructive sleep apnea using a relatively simple test for the apnea-hypopnea index to determine if a mandibular device will be effective. MATERIAL AND METHODS: A total of 68 patients with obstructive sleep apnea syndrome (OSAS) including, 31 with mild, 23 with moderate and 14 with severe OSAS were treated with a mandibular advancement device (MAD) and monitored with polysomnography. RESULTS: 25 of the 31 mild, 15 of the 23 moderate and 2 of the 14 severe OSAS patients were cured of their OSAS if a post treatment apnea-hypopnea index of less than 5 is regarded as cured. The odds ratios for success with MAD therapy are 3 for women over men, 14.9 for mild obstructive sleep apnea, 5.42 for moderate obstructive sleep apnea if severe obstructive sleep apnea is assigned an odds ratio of 1. CONCLUSIONS: The use of the apnea-hypopnea index alone is useful in mild and moderate disease to predict the effectiveness of mandibular advancement device. Treatment with a mandibular advancement device is very effective in treating mild and moderate obstructive sleep apnea. Conservative treatment with a mandibular advancement device can be successful in less severe grades of sleep apnea and may be an alternative for non-surgical patients with severe obstructive sleep apnea intolerant of Continuous Positive Airway Pressure management.

Shoulder pain and an isolated teres minor nerve lesion.

The finding of isolated teres minor denervation during examination of the shoulders using MRI occurs in 3% to 5.5% of examinations. We describe eight patients with shoulder pain, in whom electromyography revealed an isolated lesion in the motor branch of the axillary nerve to the teres minor muscle. This nerve lesion is clinically impossible to diagnose, the lack of a clear diagnosis often resulting in inappropriate treatment and therefore potentially prolonged disability. Hence, when encountering shoulder problems, neurophysiologists should examine the teres minor muscle as a matter of routine. In the MRI and ultrasound examinations of patients with shoulder problems, therefore, not only routine tendon and joint structure but also muscles should be evaluated.

Motor nervous system impairment persists in long-term survivors of childhood acute lymphoblastic leukemia.

BACKGROUND: The objective of the current study was to determine whether therapy for childhood acute lymphoblastic leukemia (ALL) results in long-lasting neurologic signs or electrophysiologic injuries within the motor tracts. METHODS: Twenty-seven children who were treated for ALL were studied clinically 5 years after the cessation of therapy by means of motor-evoked potentials (MEPs) elicited by magnetic stimulation transcranially and peripherally. An equal number of healthy children matched with regard to age, gender, and height served as the control group. RESULTS: The MEP latencies to the hands and legs elicited by stimulation at the cortex were prolonged significantly in the children treated for ALL compared with the control group, with the differences being 2.2 milliseconds [ms] (P < 0.001) from the cortex to the thenar on the right side and 2.0 ms (P < 0.001) on the left, and 1.4 ms (P = 0.004) from the cortex to the leg on the right side and 1.3 ms (P = 0.004) on the left. Correspondingly, the MEP latency from the fifth lumbar vertebrae (LV) level to the leg also was prolonged, by 1.0 ms (P = 0.005) on the right side and 0.8 ms (P = 0.005) on the left side. The calculated latency between the cortex and the LV level was not found to be significantly longer in those patients treated for ALL compared with the healthy controls. Neurologic signs, in the form of depressed deep tendon reflexes, were observed in 8% of the patients, whereas approximately 33% of the patients were found to have fine or gross motor difficulties and dysdiadochokinesia. CONCLUSIONS: Neurologic signs still persisted 5 years after therapy for ALL. Approximately 33% of the patients had fine or gross motor difficulties and dysdiadochokinesia, and demyelinative injuries to the peripheral nerve tracts were found proximally but not within the central nervous system.