The Glasgow Coma Scale (GCS) and the Reaction Level Scale (RLS85) were compared for rating neurosurgical patients in regard to ranking order of deficit severity, interobserver variability, and coverage for relevant factors. Four physicians, four registered nurses, and four assistant nurses performed 72 pairwise ratings on 47 neurosurgical patients. The rank correlation between the GCS sum score and the RLS85 was -0.94, suggesting the same ranking order of severity and indicating that the underlying concepts of somnolence, delirium, and motor responses in coma are evaluated in the same way. By the sign test, the RLS85 was shown to have better interobserver agreement than the GCS sum score and the eye-motor-verbal (EMV) profile. The interobserver grading disagreements in both scales were distributed over the entire range of responsiveness, and for the GCS sum score they were slanted to combined segments 9 to 15. The RLS85 showed full coverage of relevant factors, while 43 (60%) of the 72 test occasions in the GCS sum score and the EMV profiles showed untestable features, most often because of patient intubation. The pseudoscore (that is, the choice of value given to untestable features) affects interobserver agreement as well as the estimated overall patient responsiveness in the GCS sum score. Assessment by the order of applying the scales showed a significant effect on the GCS eye-opening scale (p = 0.01) and the GCS sum score (p = 0.03), indicating a sensitivity to environmental stimuli unrelated to the patient's status. This study demonstrates that basically the same information as that found in the separate eye, motor, and verbal scales of the GCS can be combined directly into the RLS85, which has better interobserver agreement and better coverage than the GCS sum score.

The Reaction Level Scale (RLS85) is a "coma scale" for the direct assessment of overall reaction level in patients with acute brain disorders. It is devised for reliable use even in the management of patients who are difficult to assess, such as intubated patients and patients with swollen eyelids. We here present the manual of the RLS85 and the guidelines for its use. The underlying concepts as well as limitations are outlined. Condensed information of known reliability and validity is presented. A training scheme for presumed observers (doctors, nurses and assistant nurses) is outlined. It is suggested that users of the RLS85 refer to these guidelines and in scientific reports clearly state any deviations from this present manual in order to facilitate valid comparisons between different studies and different groups of patients.

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Slow evoked cortical potentials from ten young normal-hearing subjects have been recorded as responses to linear frequency ramps of a continuous pure tone. Frequency changes from 10 to 500 Hz were studied; the rate of frequency change was varied from 0.02 to 50 kHz/s while the duration of the change was varied from 10 to 500 ms. The rate of frequency change was shown to have the greatest bearing on the responses except for frequency ramp durations below 50 ms and frequency changes below 50 Hz. The base frequencies (250-4000 Hz) and sound levels (20-80 dB HL) exerted an influence on the evoked responses that was qualitatively similar to their influence on behavioral thresholds. The direction of the frequency sweep had no significant influence on the evoked responses. A functional model is proposed in which the time derivate of the signal frequency is integrated with an adaptable integration time that is controlled by the rate of the frequency change.