David D. Daly

Treatment of narcolepsy with Ritalin

IN 1956, we reported favorably on the use of methyl phenidate hydrochloride (Ritalin hydrochloride) in the treatment of narcolepsy.1 This preliminary report described the results of therapy in 25 patients with narcolepsy who were treated from one to six months. Of these patients, 84% reported good to excellent relief of their abnormal sleepiness. Encouraged by these results, we have continued to use the drug. The present report is based on a study of 60 patients including most of the original 25.

Disturbances of swallowing and esophageal motility in patients with multiple sclerosis

AMONG the diverse symptoms of multiple sclerosis, disturbances of swallowing have received little attention. Charcot,l in his classic description of multiple sclerosis, observed: “To this symptom [dysarthria] may successively be added, especially in advanced stages of the disease, certain disorders of deglutition, of circulation, and even of respiration.” Subsequently, few authors have commented upon such symptoms. Carter, Sciarra, and Merritt,2 in a study of 46 patients with multiple sclerosis who came to necropsy, remarked that 1 patient had had a disturbance of swallowing and that the muscles innervated by the ninth and tenth cranial nerves had been involved in 15 per cent of their patients who, however, apparently had no complaints referable to their throats. Difficulty in swallowing which developed early in the illness of 2 patients with multiple sclerosis awakened our curiosity and led us to investigate this problem further. We soon discovered that disturbances in swallowing seemed not to be too unusual among patients who have multiple sclerosis. In an attempt to improve our understanding of the nature of these symptoms, we have investigated the esophageal motility of some of these patients.

Early evoked potentials in patients with acoustic neuroma

Using clicks with varying interstimulus intervals and coherent tone-bursts, early components of the auditory evoked potential (brain stem responses) were studied in four patients with confirmed acoustic neuroma. Abnormalities in responses appeared with shorter interstimulus intervals and with tone-bursts delivered monaurally to the involved ear; bilateral alterations occurred in one patient with brain stem displacement. The results indicate that BSR can provide a stable, independent, noninvasive measure of auditory nerve function useful in the early detection of acoustic neuroma. The results contribute to the understanding of the so-called human FFR.

Effects of Photic Stimulation During Sleep A Study of Normal Subjects and Epileptic Patients

IN 1934 Adrian and Matthewsl observed that if a rhythmically flashing light was shined in the eyes of a subject, waves having the same frequency as the flashing light appeared in the electroencephalogram. This phenomenon has been called “photic driving.” It appears maximally in the occipital and parietal regions and usually as a bilaterally s y m metrical rhythm. However, the term “photic driving” is not entirely satisfactory, since to some authors it has implied a response intimately linked with alpha rhythm mechanisms. As this hypothesis has not been substantiated as yet, in this study we have used the term “photic response” which does not necessarily imply any connection with alpha rhythms. The observations of Adrian and Matthews have been extended by a number of a u t h o r ~ . ~ ~ In general, when brief pulses of light are flashed in the eye at relatively slow rates (less than one flash per second), complex polyphasic responses can be recorded from electrodes placed in the occipital regions of the skull. As the flash rate is increased, the responses tend to fuse and assume more sinusoidal forms. The shapes of the sinusoidal forms may be distorted by the presence of harmonic or subharmonic frequencies of the flash rate. Photic responses may be seen over a wide range of frequencies, and they frequently persist after closure of the eyes, although under those circumstances recognition may be difficult because of mixture with spontaneous alpha rhythms. Another important effect of photic stimulation is the initiation of convulsive manifestations in certain individuals. These may take the form of myoclonic jerkings, petit ma1 attacks, or generalized convulsions.s-s In some patients the degree of sensitivity to light is such that

Coordinating DRAM and Last-Level-Cache Policies with the Virtual Write Queue

To alleviate bottlenecks in this era of many-core architectures, the authors propose a virtual write queue to expand the memory controllers scheduling window through visibility of cache behavior. Awareness of the physical main memory layout and a focus on writes can shorten both read and write average latency, reduce memory power consumption, and improve overall system performance.

The electroencephalogram in cases of benign intracranial hypertension

ELECTROENCEPHALOGRAPHERS have paid relatively little attention to the effects of simple intracranial hypertension on the electroencephalogram, having been more concerned with alterations in electric activity resulting from lesions which, in turn, may cause intracranial hypertension. In an early study, Williams1 concluded that there was no correlation between abnormality in the electroencephalogram and the pressure of the cerebrospinal fluid. However, in his study, he considered a group of cases, including supratentorial and infratentorial tumors, in which the processes leading to intracranial hypertension were not the same in all instances. Stewart,* in an experimental study, recognized the need for distinguishing the mechanisms by which intracranial hypertension developed. He injected lamp black into the cistema magna of kittens producing “active” hydrocephalus, which developed on the ninth day after injection and was associated with large slow waves in the electroencephalogram. Stewart termed this type of intracranial hypertension “increased intraventricular pressure.” In contrast to this obstructive hydrocephalus, he caused so-called generalized intracranial pressure by application of hydrostatic pressure to the foramen magnum, intravenous injection of distilled water, or ligation of veins draining the cranium. In both the acute and the chronic form of generalized intracranial pressure, the electroencephalogram was unchanged. He concluded that generalized engorgement or edema of the brain did not alter its normal electric activity. Stewart also commented on 3 patients with “meningeal hydrops” who had papilledema but no hydrocephalus. The electroencephalograms of all 3 patients were normal. His study was of great practical importance since it emphasized that the process leading to intracranial hypertension determined the occurrence of an abnormality in the electroencephalogram, an abnormality which appears only in the presence of increased intraventricular pressure. Confirmation of Stewart’s observations concerning generalized intracranial pressure came from Forster and N i m ~ ; ~ these authors showed that, in animals under anesthesia, rapid increase of the intracranial pressure by hydrostatic means did not cause change in the electroencephalogram until the pressure of the cerebrospinal fluid exceeded the blood pressure, at which time the brain waves disappeared. Subsequently, in a study of rhythmic slow discharges in the electroencephalogram, Cobb4 cast some doubt on the clinical validity of Stewart’s observations. Cobb expressed the opinion that rhythmic delta discharges were associated with lesions located in the epithalamic region, but he added, “No correlation is found with raised intracranial pressure or internal hydrocephalus.” In a study of 87 patients with tumors of the third ventricle and posterior fossa or nonneoplastic obstructive hydrocephalus, Daly and associates5 concluded that one factor determining the presence of bisynchronous rhythmic slow discharges in the electroencephalogram was the development of hypertension within the third ventricle. Other modifying factors appeared to be the rapidity of rise of intracranial pressure and the age of the patient. The hypothesis was offered that pressure on midline thalamic structures caused a disturb-

Year Book of Neurology Psychiatry and Neurosurgery

This book constitutes the 1961 Sherrington Lectures. The material covered includes not only the author’s own research with invertebrate nerve for which he subsequently received the Nobel prize but also presents a lucid and well-documented summary of related work on the structure of nerve and the physiology of myelinated nerve fibers. The style ob writing, the presentation, and the production are superb. The concepts are built in a clear orderly fashion that will make this book usehl for the beginner, yet the citations and critical discussion in areas of controversy do not speak down to the specialist and experienced worker. In this century there has been a handful of great books that document new concepts of the nature of nervous function in the context of the authors’ investigative contributions. To this select group of Sherrington, Herrick, Adrian, Erlanger, and Gasser is now added a new classic. the definitive presentation of the nerve impulse in terms of physical chemistry and ion transport. No neurologist can dord m t to have i t in his library.

The Generalized Epilepsies: A Clinical Elec-troencephalographic Study

The term “generalized epilepsies” is a translucent term that obscures various semantic problems. What is generalized the seizures, the pathologic substrate, or the interictal EEG? The proposed International Classification of the Epilepsies lays emphasis on the seizures themselves, which must be generalized from the onset and which variously consist of absences, bilateral myoclonic seizures, tonic or atonic seizures, and tonic-clonic convulsions. The classification further identifies “primary” generalized epilepsies, also termed “common generalized epilepsies,” in which patients suffer absences, myoclonic seizures, and tonic-clonic convulsions singly or in combination and in which a strong genetic influence exists. In contrast, patients with “secondary” generalized epilepsies often evince signs of diffuse or multifocal cerebral lesions and will have one or more of the various seizures mentioned above. The interictal EEG abnormalities differ strikingly in these two groups. Dr. Niedernieyer has collected prospectively 300 cases for study; in contrast to the International Classification, he based his selection solely on the EEG criterion of generalized discharges. “ A co-existence of generalized and focal seizure discharges was no exclusion from acceptance in this material but the generalized component had to be about as strong as the focal one.” For unspecified reasons he has excluded from study those EEGs that would be characterized as “hypsarhythmic.” This method of selection has yielded a heterogeneous group of patients in three major categories: primary generalized epilepsy: epileptic encephalopathy of childhood, which Niedernieyer prefers to term the Lennox-Gastaut syndrome and is in itself a miscellany of etiologies; and cases of secondary bilateral synchrony. The author develops his data in terms of these various categories. The remaining halt’ of the book is devoted to an analysis of the types of seizures, the types of EEG abnormality, etiology, and the role of age and genetic factors. In discussion, Niedernieyer introduces the concept ofdwhoumiu. He discusses at length the temporal associaticin of generalized epileptiform discharges with vertex waves and K complexes in the EEG. He believes that this indicates that the pathophysiology of primary generalized epilepsy lies in “ a faulty arousal mechanism, which is termed ‘dyshormia’ . . . which might be due to a biochemical disturbance which is genetically transmitted.” Although i t does not contribute a deeper understanding of the pathophysiology of these epilepsies, the term constitutes a useful rubric that emphasizes the interaction between circadian cycles and seizures. That different types of seizures have preferential times (if occurrence in the 24 hour day-night cycle has been documented repeatedly since the time of Gowers. Yct, until relatively recently, this obviously highly significant fact has been largely ignored. In summary, this is a book on a poorly understood group of epilepsies that constitute a wide spectrum of neurologic disease and serve to emphasize why epilepsy remains a stubborn enemy. On the positive side, it contains a thorough review of the clinical and experimental literature, together with a critical analysis. That the author fails to come up with a coherent classitication of the generalized epilepsies indicates only the complexity of the problems and the major gaps in our knowledge. On the negative side, the author’s division of primary generalized epilepsy into typical and atypical forms seems artificial and based on inconsistent criteria and tenuous evidence. While the International Classification of Seizures has not won universal acceptance, I would fault the author for not attempting to use it in preference to the older terminology. The term gmnd-ma1 is anachronistic and obviously ambiguous, since it fails to differentiate tonic-clonic convulsions gcneralized from the onset from those secondarily generalized from a focal onset. Finally, theauthorisguiltyofthe “numbersgame.” in whichhe presents numerous tables involving data on age, seizure types, and types of epilepsies without any statistical evidence indicating that these data differentiate significant groups. Because of its highly technical subject matter, this work will interest primarily epileptilogists and electroencephalographers.

Differentiation of Automatisms of Focal or General Origin

Differentiation and description of nonconvulsive seizures began in the nine teenth century. Jackson introduced the term automatism to refer “all kinds of doings after epileptic fits. . . .” However, the term gradually became associated with confusional states following complex partial seizures. At the same time the earlier term “petit mal” originally applied to all varieties of nonconvulsive seizures gradually became restricted to very brief attacks occurring primarily in children, beginning without warning and commonly described as arrest of consciousness without other manifestations. In this century the term “psychomotor seizure” originally referred to complex partial seizures but later became equated solely with automatisms. The Classification of Seizures proposed by the International League Against Epilepsy has abandoned the term “petit mal,” proposing in its place “absence.” Simple absence, regarded as the archetypal seizure, was described as a brief loss of consciousness, beginning without warning, ending abruptly and without loss of postural tone. Since some children with simple absence also had more prolonged episodes with automatic behavior, the clasdication also included the term compZex absence. In contrast, the Classification also recognized partial seizures with “impairment of consciousness only,” in addition to types with “psychomotor symptomatology (automatisms).” In a study of complex partial seizures, CafE reported 4% of patients as having attacks with impairment of consciousness only. Classification has benefitted from newer technologies of video recording of seizures combined with telemetery of the EEG to permit precise observation and objective description of the behavioral events that characterize such seizures. However, these intricate, and not always obvious, differentiations have caused confusion and have led the International Commission on Terminology to reconsider the problem. The International classification now differentiates between tonic-clonic convulsions generalized from the onset and those secondarily generalized. It seems reasonable to consider whether an analogous differentiation of non-convulsive seizures characterized by impaired responsiveness and confusion would be useful. Such a differentiation has two obvious justifications:

The Nervous System and Electric Currents: Proceedings of the Fourth Annual National Conference of the Neuroelectric Society, held in San Antonio, Texas, Mar. 10–12, 1971

This volume conl.ains the proceedings of the fourth annual conference of the Neuroelectric Society held in March 197 1. Members of this society have focu:i;ed their attention not o n the electrical events that accompany neuronal activity but rather on the effect of superimposing electrical fields upon ongoing biological or neural functions. A particular area of interest has been ‘the transcranial application of c u r r e n t s t o induce electroanesthesia and electrosleep. The volume consists of 8 sections, with the first 3 devoted 4.0 “electroneurophysiology.” The articles in th,ese 3 sections are extremely diverse, ranging from a theoretical analysis of the size of lesions induced by high-frequency stimulation through a spherical I-mm. probe to changes in steady potentials in bones during immobilization and to a quasiphilosophical system of “psychosynthesis” that attempts to relate holography to psychotherapy. Subsequent sections contain articles categorized under neurophysiological effects of electric currents, peripheral nerve and spinal