Citations

The aim of this study was to investigate the development of ideas about the nature and mechanism of the fixed dilated pupil, paying particular attention to experimental conditions and clinical observations in the 19th century. Starting from Kocher's standard review in 1901, the authors studied German, English, and French texts for historical information. Medical and neurological textbooks from the 19th and 20th centuries were reviewed to investigate when and how this information percolated through neurological and neurosurgical practices. Cooper experimented with intracranial pressure (ICP) in a dog in the 1830s, but did not mention the pupils. He described dilated pupils in clinical cases without referring to the effect of light. Bright demonstrated to have some knowledge of the pupil sign (clinical observations). Realizing the unreliability of the pupil sign, Hutchinson in 1867–1868 tried to reason in which cases trepanation would be advisable. Von Leyden's 1866 animal experiments, in which he increased CSF volume by injecting protein solutions intracranially, was the first observation in which the association between fixed dilated pupils and increased ICP was established. Along with bradycardia and motor and respiratory effects, he noticed wide pupils were usually present in a comatose state. Asymmetrical dilation could not always be attributed to increased ICP, but to an oculomotor nerve lesion. Pagenstecher in 1871 extended knowledge by meticulously studying consecutive pupil phenomena with increasing pressure. In 1880, von Bergmann emphasized the significance of the ipsilateral dilation in experiments as well as in clinical cases. He distinguished the extent of pressure increase and its duration. Probably confusing irritation (epileptic head turning to the other side with pupil dilation) and lesion effects, he suggested a cortical area responsible for oculomotor phenomena, indicating what is now known as the frontal eye field. Naunyn and Schreiber (1881) understood the relationship between increased ICP with pupil dilation and decreased pulse frequency and blood pressure, warning not to decrease the latter. Concentrating on experimental traumatic effects, Duret (1878) investigated compression and commotion, in which he distinguished two phases, notably pupil constriction by bulbar lesions, due to CSF shock, followed by dilation from congestion and inflammation, due to blood around the oculomotor nerve. The key observation of a fixed dilated pupil as a sign of acute mass effect came gradually and after some localization stumbles. Following the period of extensive experimental research in ICP, the results of which were translated to clinical observations, the prognostic significance was gradually acknowledged by authors of neurological textbooks. It is well known that Cushing did similar experiments in Berne (1900–1901), and later suggested he would not have done so if he had studied the literature.

Background: The expertise required for proper electroencephalography (EEG) setup can make the 10-20 array unwieldy in the hospital setting. There may be a role for an EEG array with reduced leads to improve the efficiency of inpatient practice. Methods: Clips from 100 EEG records, 50 ictal and 50 non-ictal, in adult inpatients from January 1, 2007, to January 1, 2012, were retrospectively reviewed and selected for digital lead reduction and blind review. Two epileptologists reviewed these tracings and documented the presence of seizures and severe disturbance of background. The reduced array included 7 leads spanning the scalp. Three different montages were available. Sensitivity and specificity of the reduced array were calculated using the formal EEG report as the comparison standard. Results: For the detection of any seizure, the reduced array EEG had a sensitivity of 70% and specificity of 96%. Sensitivity for identifying encephalopathic patterns was 62% and specificity was 86%. Focal seizures were more readily identified by the reduced array (20 of 25) than were generalized ictal patterns (13 of 25). Conclusion: The reduced electrode array was insufficiently sensitive to seizure detection. Reducing EEG leads might not be a preferred means of optimizing hospital EEG efficiency.