Alfred Uihlein

Depth electrographic study of a fast rhythm evoked from the human calcarine region by steady illumination.

Abstract In the course of investigation following implantation of depth multielectrode leads in an epileptic patient a fast discharge was observed in one electrode, located in the left occipital lobe, when the lights of the room were switched on and off. On the basis of roentgenographic evidence as well as the results of visual, photic and electric stimulation, the electrode involved in this phenomenon was estimated to be located in the anterior calcarine cortex or underlying white matter. Constant illumination (18 to 1200 foot-candles) provoked in this part of the brain a response characterized by an initial slow potential (“slow on-response”), followed by a fast discharge of around 50 c/sec. This evolved after a variable time into a discharge of 20 to 25 c/sec. that gradually declined and was usually over after 30 to 35 sec. (“fast on-response”). A pattern similar to the on-response, but of lower voltage and shorter duration, was observed when the stimulus was switched off (“slow” and “fast” off-response). The response was usually reduced by closure of the eyes and enhanced at their opening. The response was present and sometimes intensified during sleep. Various effects could be provoked by changing the duration and the intensity of illumination. There was some degree of similarity between the initial slow potential of the “on” and “off” response and (1) lambda waves and (2) responses to intermittent photic stimulation at low rate. These findings are discussed on the basis of previous animal experiemental studies.

Depth electrographic studies of a focal fast response to sensory stimulation in the human

Abstract In an epileptic girl, during depth electrographic studies with chronically implanted electrodes, a focal fast response to different sensory stimulation (auditory, painful, tactile, proprioceptive, photic, and olfactory) was recorded from one discrete location in each side. On the basis of anatomic-radiologic studies, the electrode positions were estimated as being deep in the posterior temporal or parietal lobes, immediately posterior to the pulvinar and anterior to the ventral portion of the calcarine region, at about 25 mm from the mid-line. The response consisted of a burst of fast (40–45 c/sec) rhythmical waves 100–150 μV in amplitude and 0.5–1 sec in duration, appearing after 100–200 msec of latency. During wakefulness the response was accompanied by a simultaneous generalized flattening of other activities; during sleep it was more conspicuous and often was followed by a recovery of wakeful activity. The response showed rapid habituation. The active electrodes also recorded epileptogenic activity, although this was not related to sensory stimulation. The pattern described does not seem to be related to the epileptic disorder. Its nonspecific responsiveness to all sensory modalities is unique and suggests a relationship to mechanisms of sensory integration.

Neurologic Changes, Surgical Treatment, and Postoperative Evaluation

Our analysis suggested that in patients operated on for primary lumbosacral disc protrusion, a more lasting postoperative result could be anticipated if disc removal and fusion were carried out simultaneously, but statistical analysis did not substantiate this impression. Patients who experienced a recurrence after removal of the protruded fifth lumbar intervertebral disc without fusion usually required fusion later. At the fourth lumbar level, on the other hand, the addition of a fusion operation at the time of the primary operation did not appear to increase the chances for a good postoperative result. Disc protrusions at the third lumbar level usually were removed without fusion because the likelihood of pseudarthrosis increased proportionately with the length of the bone graft applied. With disc protrusions occurring simultaneously at the lumbosacral interspace and the interspace above, a fusion operation performed at the same time as removal of the two discs appeared to offer a more lasting result. Since our patients were selected for operation by an orthopaedic surgeon as well as a neurosurgeon, a valid objection could be made on the basis of selection of patients. Although the results in all categories are encouraging, it is disappointing that they are not better. Pain in the lower part of the back and in the leg is not always due to degenerative disc disease and careful selection of patients appears essential to achieve better long-term postoperative results.

Profound Hypothermia and Total Circulatory Arrest in Neurosurgery: Methods, Results, and Physiologic Effects

Until recently hypothermia in neurosurgery had been limited to surface technics and temperatures of about 28° C; the potential hazard of ventricular fibrillation precluded further cooling. The development of extracorporeal perfusion technics has effectively circumvented this limiting factor, permitting temperatures to be lowered to 15° C and below with little additional hazard to the patient. At these temperatures the oxygen requirements are such that the brain and other vital organs can withstand total circulatory arrest for periods of 30 to 40 minutes without apparent damage.

Acute visual failure as a neurosurgical emergency.

Section ofNeurological Surgery, MayoClinic andMayoFoundation, tRochester, Minnesota MoREoften than notvisual failure istheresult ofadisorder oftheglobe, and hence lies within theprovince oftheophthalmologist. However, alesion involving theoptic pathways mayoccasionally beresponsible foracuteloss ofvision (List, Williams, andBalyeat, 1952; Love, Dodge, andBair, 1955; Uihlein, Balfour, andDonovan, 1957) andattimes suchalesion isoverlooked because athorough medical examination wasnotconducted whenthe patient first consulted hisphysician (Baker andRucker, 1950; Jefferson, 1955; MacCarty, Lillie, Daly, Hollenhorst, andHolman, 1957). Ideally, ifirreparable visual lossisto be prevented, thecauseshouldbe determined early enough toalloweffective treatment. Thisrequires a thorough medical examination, whichshould include ophthalmological investigation, roentgenograms oftheskull, neurological examination, and accurate plotting ofthevisual fields (Hughes, 1954). Inthemoredifficult diagnostic problems, laminagrams oftheskull andcerebral angiography, as wellassagittal sinus venography andpneumo-encephalography, maybe

The Value Of Angiograms: In Diagnosis of Convulsive Disorders and Other Intracranial Lesions in Children

The results of cerebral angiography in cases of 138 children with convulsive disorders or suspected intracranial lesions are reviewed.On the basis of the findings, the authors conclude that the test is safe and of value in diagnosing cases of the type studied.