Significance of electrical brain activity in brain-stem death.

A 46-year-old man was diagnosed clinically brain dead after sustaining head trauma. The patient was in deep coma, brain nerves were unresponsive and spontaneous breathing was absent. However, EEG showed well preserved activity, but no reactivity to external stimuli. EEG activity disappeared within 40 h. BAEP were highly abnormal, flash-VEP as recorded 3 h after the diagnosis of brain stem death was of high amplitude but of simplified form. The neurophysiological findings revealed that the main reason for deep coma was brain stem damage while cortical activity was still present. This condition raises ethical questions when brain death is diagnosed clinically prior to removal of organs for transplantation.

A follow-up EEG study in diabetic children.

498 electroencephalograms (EEGs) were recorded from 195 diabetic children during a follow-up study. The children were divided into stable and labile groups according to diabetes control. The labile group was further subdivided into hypoglycaemic, ketoacidotic and mixed groups. In general it was found that the labile children had significantly more abnormal findings in their EEGs than the stable children, as expected. This applied particularly to generalized discharges with spikes and sharp waves or focal findings, but not to cases with only a diffuse-slowing. Nonstatistical differences in EEG abnormality were seen between the hypoglycaemic and ketoacidotic group--an unexpected finding. During the follow-up the labile group more often had an increasing EEG abnormality than the stable group. For those children who had an EEG abnormality but without an increasing tendency, there was no difference in the EEGs between the labile and stable children. It was concluded tht some of the EEG abnormalities are acquired, and apparently produced by a metabolic disturbance caused by diabetes. However, other causes may be of genetic or perinatal origin, or perhaps a combination of different causes. Because of the multifactorial aetiology of the abnormalities, EEG cannot at present be recommended for routine testing of the effects of metabolic disturbance in diabetics.

Electroencephalogram during and after an acute attack of asthma in children.

EEGs were recorded in 12 children who were admitted to hospital because of an asthmatic attack. One EEG was recorded during the attack, one immediately after, and a third EEG several weeks later. The severity of the attack was classified as moderate in eight children, severe in three and very severe in one child. There was a corresponding change in the blood gases, but other laboratory values (electrolytes, glucose, etc.) were normal. Contrary to previous findings, no change was seen in the three successive EEG recordings which had been related to the attacks. It is therefore concluded that an asthmatic attack as such does not give rise to changes in the EEG, and a complicating factor should be suspected if such changes are seen.

Quantification and calibration of flash stimuli in clinical research.

Despite the relatively wide use of flash-type stimuli in VEP studies, no universally accepted standards or methods of measurement for these stimuli are in existence. Several methods have been described for the determination of flash-intensities, however, the majority of these methods are not sufficiently rigorous, or are based on overly optimistic assumptions on the ideal nature of flash-stimulators. We describe here a simple method for the determination of flash-stimulus energies and absolute peak intensities. Our method does not require specialized optometric instrumentation, and should be readily adaptable to any modern laboratory.

The correlation of EEG compressed spectral array to Glasgow Coma Scale in traumatic coma patients.

We have studied 20 comatose intensive care patients with head injuries and/or intracranial haemorrhage in order to compare two different monitoring methods of the central nervous system. The level of unconsciousness was followed on the Glasgow Coma Scale (GCS). EEG was monitored continuously with the compressed spectral array (CSA)-method. CSA findings were classified into six categories according to the frequency content, reactivity and the amount of isoelectricity. The patients were divided into four groups according to the outcome: well-recovered, moderately recovered, poorly recovered and dead. The prognostic value of the data obtained with the GCS method was compared with that obtained by CSA. The CSA and GCS methods give information based on different neurophysiological backgrounds. This explains why the correlation of these methods was only moderate. When combining the information received from these two methods the predictability improved. In many acute situations CSA gave information about changes in the brain function, which could not be seen in GCS. The results suggest that CSA is not only a supplementary method to GCS but also a different approach to the monitoring of an unconscious patient.

Visual evoked potentials in high-risk infants.

Flash VEPs were recorded in 109 high-risk infants, and the result were compared with the clinical outcome of the infants at the age of one year. 87 of the infants (80%) had a normal outcome and also seemed to have normal VEP maturation. This material was used as a reference for infants with abnormal outcome. Altogether, 20 infants (18%) had abnormal VEPs. In most of these repeated VEPs were recorded. In 70 cases the first VEP was recorded at an age of less than three months. Among these 57 children had normal outcome, with abnormal VEPs in 8 cases (14%). 13 infants who had an abnormal outcome had abnormal VEPs in 7 cases (54%). 7 infants of them had poor outcome, and they had abnormal VEPs in 6 cases (86%). The difference between normal and abnormal outcome was statistically significant. The present results indicate that it is possible to predict the poor outcome but not the moderate abnormality by VEP. The absence of VEP or its abnormal wave form were the most important parameters to predict the prognosis. Our present opinion is that VEPs should be recorded selectively, e.g. according to the findings in ultrasound examination, at least twice, the first time as soon as possible after birth and the second time at the age of two months.

[Functional electric stimulation of the phrenic nerve and its clinical significance]. / Funktionell elstimulering av nervus phrenicus och dess kliniska betydelse.

The peripheral parts of the phrenic nerve are healthy in some of the patients who require permanent or intermittent care in a respirator owing to reduced respiratory function of central aetiology. In such cases, continual care in a mechanical respirator can be avoided, and diaphragm function maintained by means of functional electrical stimulation (FES) of the phrenic nerve with carefully controlled electrical impulses. The method is suitable for use in certain cases of quadriplegia, or in patients with sleep apnoea. Experience with the method has shown that health care costs can be reduced and the patients' quality of life improved. In some cases, the patient may even regain partial work capacity.