A. Earl Walker

The electroencephalographic changes after hemispherectomy in man

Abstract The electroencephalographic findings in four cases of right hemispherectomy are presented. In three cases the voltage of the activity on the unoperated side was markedly diminished; in one case unchanged. In all four cases a rhythm in the alpha range was present on the hemispherectomized side. In one case photic stimulation induced a better response on the operated than on the unoperated side; in another case the reverse was true.

CHRONIC POSTTRAUMATIC HEADACHE

Headache for a few weeks after a head injury is a common observation, but its persistence for years is considered a rarity. Yet, if one examines the reported series of wounds of head from World Wars I and II, it is apparent that headache is a very common sequela. In fact, as many as 80% of men in some series are said to have headaches many years after their injury.16 A recent study of 313 men known to have sustained a head injury 15 years previously in Warld War II has confirmed this impression; 64% of this series had headaches which they attributed to their injury.

The contribution of depth recording to clinical medicine

Abstract The recording of electrical activity within the depth of the brain has made many contributions to the clinical sciences. 1. 1. It is of value as a diagnostic technique in certain obscure epilepsies. 2. 2. It has given new concepts of the epileptic syndrome. 3. 3. It is an aid in the delimitation of the zone of epileptic activity. 4. 4. To stereotactic orientation, depth recordings and stimulation add a fourth and physiological dimension. 5. 5. The findings from depth recordings in psychosis have indicated a possible organic substrate for certain disturbed mental states. 6. 6. Future applications of depth recording for biochemical determinations offer promising avenues for exploration of cerebral function.

Depth EEG studies in a patient with fourteen and six per second positive spikes

Abstract Report of an 18-year-old patient with minor seizures, rare grand mal and recent personality change. Nine EEG studies with combined depth and scalp recording revealed 14 and 6/sec positive spikes. This pattern was seen at different levels, especially in the thalamo-capsular region and in the neighborhood of the putamen. However, the polarity of the deep “14 and 6” bursts was equivocal in the depth while unequivocal positivity was seen in the scalp recording.

Response of experimental epileptic foci to intravenous and topical metrazol

Abstract The intravenous injection of Metrazol in epileptic monkeys having had alum cream applied to the motor cortex may induce focal electroencephalographic abnormalities, increase focal abnormalities already present and/or result in focal convulsive seizures. The Metrazol convulsive threshold is lower in such epileptic monkeys than in normal animals. Following the application of Metrazol to the cerebral cortex of the normal monkey, high voltage single spikes or bursts of 2 to 3 spikes appear from the site of application and commonly from the same area of cortex on the opposite hemisphere and from areas adjacent to the site of application. These spikes recur every 4 to 5 sec. and persist for 3 to 10 min. The foci of epileptic monkeys are more sensitive to the convulsive drug than the remainder of the cerebral cortex in the same animal or the cortex of normal animals and respond by spiking to greater dilutions of the convulsive drug. The resulting discharge may be prolonged and may spread over the cortex producing a generalized seizure pattern.

DC potentials of temporal lobe seizures in the monkey

SummaryIn 8 monkeys, made epileptic by alum or penicillin injection into temporal lobe structures, 40 seizures were studied by both DC cortical potential and subcortical EEG recordings.Eighteen seizures of lateral temporal origin had an abrupt negative DC potential shift of 0.5 to 2.0 mV in and around the focus. The frontal, parietal and occipital cortices did not develop DC potential changes, perhaps due to the limited propagation of the neocortical seizures.Twenty-two seizures of medial temporal origin showed a negative shift of the anterior, inferior or lateral temporal cortex in 85% of seizures. The other 15% had a positive or no shift. In hippocampal seizures, a positive displacement was sometimes seen prior to the main negative shift in the lateral temporal cortex. The remote cortex developed only a minimal positive shift in 30% of the mediotemporal seizures.A marked negative shift in the frontocentral cortex was the first sign of impending generalization, which may result from a series of chain reactions with seizure propagation, involving more and more structures of the brain.Registration of DC potentials in temporal lobe seizures may give insight into the nature of abnormal EEG activities and to some extent into the origin of seizures.ZusammenfassungAn 8 Affen, die durch Aluminium- oder Penicillineinspritzungen in Gebiete des Schläfenlappens epileptisch gemacht worden waren, wurden 40 Krampfanfälle sowohl an Hand der Gleichstrompotentiale der Hirnrinde als auch durch subcorticale EEG-Ableitungen untersucht.18 Anfälle mit Ursprung im seitlichen Schläfenlappen begannen mit einer plötzlichen negativen Potentialänderung von 0,5–2 mV in und um den Krampfherd. Die Rinde des Frontal-, Parietal- und Occipitalhirns zeigte keine Gleichspannungsänderung, vielleicht, weil die neocorticalen Anfälle sich nur sehr beschränkt ausbreiten.22 Anfälle aus dem mittleren Schläfenlappengebiet verursachten eine negative Schwankung in der vorderen, unteren und seitlichen Schläfenlappenrinde bei 85% der Anfälle. Die anderen 15% zeigten eine positive oder keine Potentialänderung. Bei Anfällen, die im Hippocampus entstanden, zeigte sich manchmal eine positive Gleichspannungsänderung, bevor es zu der negativen Spannungsänderung in der seitlichen Schläfenlappenrinde kam. Die entfernten Rindengebiete ließen bei den mediotemporalen Fällen nur eine minimale positive Gleichspannungsänderung bei 30% der Anfälle erkennen.Eine deutliche negative Spannungsschwankung im frontozentralen Cortex war das erste Zeichen drohender Generalisation des Anfalls, was möglicherweise durch eine Reihe von Kettenreaktionen bei der Anfallsausbreitung zustande kommt, die mehr und mehr Strukturen des Gehirns ergreift.Die Registrierung von Gleichstrompotentialen bei Temporallappenanfällen gibt uns Einsicht in die Natur abnormer EEG-Tätigkeiten, bis zu einem gewissen Grade auch in den Ursprungsort der Anfälle.

Anterolateral chordotomy for relief of pain.

Among the factors which have been cited as influencing the success or failure of chordotomy are the disease responsible for the pain, addiction to drugs, duration of pain, neurosis, organic neurologic involvement, localization of the pain, the type of anesthesia, and the depth of the operative incision. An analysis of the results of chordotomy in 121 patients is presented which considers these and other aspects of the operation. Chordotomy relieved the pain completely in 67 per cent of the cases, produced a fair result in 21 per cent, and failed in 7 per cent.

Threshold studies on production of experimental epilepsy with alumina cream.

Conclusions 1. There appears to be a quantitative threshold for production of chronic experimental epilepsy in the monkey with intracortical injection of a standardized preparation of alumina cream. 2. The level of this threshold for the motor cortex of the Macaca mulatta is 0.1 cc of alumina cream, containing 18-22 mg of aluminum/cc.

The treatment of epilepsy by cortical excision

Summary 1. Surgical treatment for focal epilepsy should be considered when medical management has failed. 2. The focal nature of an epilepsy may be suggested by the clinical history, the electroencephalogram, pneumoencephalogram, and angiogram, but only established by the critical examination of the entire clinical picture colored by the results of the various diagnostic tests. 3. Three cases are presented illustratingthe various types of cortical resections for focal epilepsy. 4. Depending upon the extent of thefocus, subpial resection, partial lobectomy, or hemispherectomy may be necessary to eliminate the abnormal activity. 5. The results offer promise to agroup of focal epilepsies otherwise considered incurable.

Effect of Strychnine on the Gat's Electrocerebellogram

Summary When strychnine is applied topically to the cats cerebellum, injected intravenously or into the dentate nucleus in doses of .018 to .022 mg per kilo, or injected into the cerebellar cortex in doses of 0.3 mgr the electrocerebellogram develops rhythmical waves with a frequency of 10-30 per second and a voltage of 100 to 400 microvolts occurring in periodic discharges of 30 seconds to 3 minutes duration and recurring at intervals of 1 to 3 minutes for 30 minutes to an hour.