Molecular genetics

Molecular genetics

ELSEVIER Electroencephalography and clinical Neurophysiology 94 (1995) 385-388 o Book Reviews edited by E. Niedermeyer and P.M. Rossini Atlas of ad...

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Electroencephalography and clinical Neurophysiology 94 (1995) 385-388

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Book Reviews edited by E. Niedermeyer and P.M. Rossini Atlas of adult electroencephalography. - W. Blume and M. Kaibara (Raven Press, New York, 1995, 569 p., Price: U.S. $99.00) Dr. Blume had made a substantial contribution in 1982 with his Atlas of Pediatric EEG and the present one on adult EEG represents another significant advance in our field. In the Preface he and his technologist, Kaibara, point out that this book "complements its companion volume Current Practice of Electroencephalography edited by D.D. Daly and T.A. Pedley," although published as long as 5 years ago. In this atlas there are 8 chapters: after a very brief introduction, artifacts (34 p.) follow, then normal phenomena (68 p.), focal (68 p.) and generalized (58 p.) epileptiform abnormalities, seizures (64 p.), non-epileptiform abnormalities (28 p.) and finally coma (30 p.). References are next but are somewhat scanty (only 58 p.) and a useful subject index finishes off this excellent atlas. Many statements could be made about the clarity of the EEG epochs with their helpful legends in depicting nearly every normal and abnormal pattern ever described. After acknowledging the excellence of this atlas, this reviewer will try to comment on more interesting controversial points, which do not significantly detract from the high quality of this work. Similar to Dr. Blume's previous atlas on pediatric EEG, the present volume "suffers" from the riches of many examples of a given pattern. The authors are to be complimented to show the same pattern with the same or different montages if a point is made about its variability, but the repetition of the same pattern without any special point adds greatly to the number of pages, frustration of the reader and finally to the cost of the atlas. Examples are slow alpha variant (5), normal alpha (15), photic driving (8), wicket temporal spikes (14), theta in drowsiness (10), etc. Also adding to unrewarded effort is the designation with each and every figure that the calibration signal is (always) 1 sec in duration and (usually) 50 ktV. A simple statement at the beginning would seem to suffice that, unless otherwise stated, the calibration is 1 sec and 50 ~V. At the beginning the authors warn the reader that "apiculate" is a "commonly used" word, meaning sharply contoured, and will appear frequently in the atlas. They were correct about its frequent usage, but I cannot find this word in the Daly and Pedley atlas, nor among the terms recognized by the International Federation, etc. I trust that it will be new to nearly all readers. Other minor points include the depiction of typical spindles at 13 (rather than the classic 14) Hz, the use of abbreviations, like PLEDs, before they are defined, the demonstration of the "squeak" phenomenon by showing very fast beta activity (rather than fast alpha), after eye closure, etc. Some examples can be given of unclear patterns that in my opinion may confuse the reader. Lambda was said to be found in as many as 50% of normal EEGs and examples show some minor occipital deflections that are not associated with time-locked eye movements, as they should be by definition of the International Federation. Theta activity and wicket spikes on the temporal areas were included among the "normal phenomena," but later in one figure the wicket spikes with slow activity "suggest focal dysfunction" and a prolonged sequence of temporal theta was said to be "abnormal at any age." This reviewer was delighted to see that Dr. Btume is not summarily dismissing all of these interesting wave forms as normal phenomena and some of their details can spell out which should be normal and which should be considered as abnormal.

This latter point introduces one major, continuing problem in clinical EEG, namely, the significance of various controversial wave forms. This reviewer now understands one more reason a certain group of trained EEGers have traditionally disregarded most of these patterns. Examples shown of 14 and 6 / s e c positive spikes, 6 / s e c spike and wave complexes, psychomotor variant and small sharp spikes were at times unclear and some of them would not have been accepted by this reviewer as a true example of the phenomenon in question. In one case positive spikes were said to be seen o n C3, 4 and P3,4 electrodes, but were nearly absent on a referential linkage, which shows them best. Very fast beta riding on top of theta activity easily converts this wave form into something like the 6 / s e c spike and wave complex, but the " s p i k e " component may really then be only a piece of fast activity rather than a clear example of the 6 / s e c spike and wave complex. Similarly, theta activity with very fast beta rhythms on the temporal areas were at times presented as "psychomotor variant." The notch that usually appears in this pattern is the harmonic of 1 0 - 1 2 / s e c with the 5 - 6 / s e c activity, rather than just very fast beta rhythms. Finally, a number of examples are shown of small sharp spikes (SSS) that are bilaterally synchronous and symmetrical; the Gibbses early on made clear that these SSS are rarely generalized and, although SSS are usually found on both sides, they are only rarely bilaterally synchronous. In summary, this reviewer can better understand why some of these patterns can be easily dismissed if their definition is so broad. For one who has spent considerable time writing about these interesting patterns, I was interested to see that the authors acknowledged that under certain circumstances the 6 / s e c spike and wave complex may be related to seizures. So it is for other wave forms, and the details make all of the difference, as is the case for most phenomena. Certain other points were made clear by the authors that are important and need emphasis. Examples include the disappearance of the alpha that is not always the first sign of drowsiness and that some delta bursts in patients over 60 years of age in drowsiness may be normal, as are blunted V-waves. Finally, only one typographical error was found as an example of the carefulness of the authors. In summary, this atlas by Dr. Blume and Mr. Kaibara represents a significant contribution to clinical EEG and is highly recommended for the entire EEG community, both physicians and technologists. Nearly all wave ,forms, both normal and abnormal patterns, are well described and depicted in this magnum opus.

John R. Hughes University of lllinois Medical Center, Chicago, IL (USA)

Molecular genetics. - D~I.H. Brock (Cambridge University Press, New York, 1993, 301 p., Price: US $24.95) The title of the book sets up a serious dilemma for the author, given that clinicians in general have little practical use for (or to be honest, interest in) molecular genetics in their daily practices. The intent of the book is noble, however, and I should not be too critical lest it dissuade

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Book Review / Electroencephalography and clinical Neurophysiology 94 (1995) 385-388

authors from undertaking similar attempts to make an interesting and useful scientific tool accessible to all. Writing on molecular genetics can be surprisingly difficult. Although the general concepts embodied in the science are actually quite simple and straightforward, the details can be daunting, and yet it is in the details that true understanding lies. Reconciling these problems requires not only understanding of the topic, but also familiarity with the knowledge base (or lack thereof) of the intended audience, as well as extraordinary writing skill in explaining the more confusing details without losing the reader in unnecessary details. The basics of Mendelian inheritance are covered in the first chapter of the book, and here are seen the basic flaws of the book. In an attempt to be simple and brief, some concepts come across as confusing, and others are given more prominence than necessary. For example, 3 pages are devoted to the Hardy-Weinberg law, a concept applicable only to randomly mating populations, making it of questionable value to human populations (and certainly to clinicians). The fact that the law is never again mentioned in the book is good evidence of its lack of relevance. Although the author does quite well in his historical overviews of the topics covered in this book, the problem of balancing simplicity with the necessary detail is a problem throughout the book. There are many other books available that provide a good introduction to the basics of molecular biology. "Recombinant D N A " by Watson et al. is probably the best example. Where "Molecular Genetics for the Physician" is more valuable in its reviews of what is known of the molecular biology of heritable diseases and cancers. However, these brief reviews are not sufficiently complete to serve as references by themselves nor are they current (for example, almost nothing of mitochondrial disorders is addressed). If this book is truly intended for clinicians, it needs to be revised.

significance of depression of activity is well stated. There is a new brief section on the elderly, plus a complex and detailed figure of normal EEG patterns as a function of age and state of alertness. The helpful and rarely discussed complications of the EEG and the EEGer in medico-legal situations are retained. Dr. Hughes properly differentiates between brain death and cerebral death. He retains faith in double-distance derivations. Thus, records from 8-channel instruments necessitate use of only 9 of the basic 19 scalp electrodes for ECS determination. There is much emphasis on artifact identification and the critical importance of sensitivity. It is difficult to believe that 8-channel instruments with reduced electrode coverage are often used for ECS determination. There is still a somewhat "dated" flavor to this highly personal EEG book. It is avowedly not written for qualified EEGers and, by implication, for the more than 2600 ABRET boarded technologists. The 1951 terminology of 1 0 / s e c alpha has been updated only to "10 c / s e c , " rather than to Hz. Likewise, "resistance" is used for impedance and "amplitude" for voltage. Other idiosyncratic features involve the persistent use of the passive voice and a very liberal use of boldface and italics. The index lists a plethora of acronyms, including BETS, BORT1~, DB, FIRDA, FOLD, FAR, HVS, IDR, PLEDS, PLEDSPLUS, PTO, POSTS, RMTD, SEM, STOP, and WHAM, many .of which may not be familiar to the reader. The more common acronyms of REM, NREM, SSS, etc., etc. will fare better. All bibliographies must reflect the interests of the writer(s); thus, 10% of the 222 citations in this book refer to Hughes. Despite the limited addition of some new material, the book succeeds in its avowed purpose of presenting EEG to the relatively unsophisticated physician.

Leland J. Scott

Department of Neurology, Medical College of Virginia, Richmond, VA (USA)

C.E. Henry

Developmental and Metabolic Neurology Branch, National Institutes of Health, Bethesda, MD (USA)

EEG in clinical practice (2nd edition). - J.R. Hughes (ButterworthHeinemann, Boston, MA, 1994, 242 p., Price: US $59.95) While searching for my copy of the 1982 edition of this book (loaned, as usual, and, as usual, not returned), I chanced to look at the by-now rare copy of what is inarguably the first American book on clinical EEG. Robert S. Schwab in 1951 used the same title and his book sold for $6.50. After considerable delay, I obtained a library copy of the Hughes first edition. Between August, 1985 and May, 1992, it had been borrowed 21 times. With the world-wide plethora of EEG books in the last several decades, this is a respectable number. It is a compliment to the author, there being so few single-authored contributions any more, that the publishers urged a second edition. This new edition has a more efficient typeface for both figures and text which are, nevertheless, more or less identical to those of the first edition through page 43 and throughout most of the book. Hughes has corrected a curious reversal of electrode lateralization. There is a very simple account of electrode placement, montages and polarity. Text and figures are technically free of error but given in numbingly excessive detail. There is little reference to such matters by other workers. Although this simple topic has been much overemphasized, no competent EEGer or technologist has a problem with polarity nowadays. All assume that h e / s h e has the solution. The infallible rule for this reviewer and for Schwab is that when input 1 is more negative, the pen invariably goes up and all else follows inexorably. The brief summary of abnormal EEG patterns and associated clinical conditions retains sensibly cautious admonitions regarding specific relationships. It is helpful in listing the wide range of possible etiologies. The reader can even learn about mitten patterns, both A and B. The possible

Essentials of clinical neurophysioiogy. - K.E. Misulis (ButterworthHeinemann, Boston, MA, 1993, 306 p., Price: US $75.00) The goal of this book, as outlined in the preface, is " t o provide the reader with a single source to guide competent performance and interpretation" of clinical neurophysiological tests including electroencephalography (EEG), electromyography (EMG), nerve conduction studies, evoked potentials (EPs), and polysomnography. This is a worthy goal but, unfortunately, it has not been satisfactorily achieved by the present volume. The subject matter is generally presented in a superficial and uncritical manner. In some instances the information is either inaccurate or, at least, confusing. For example, in the section on basic electronics, considerable length is devoted to the proof of very simple relationships such as the equivalent resistance in serial and parallel circuits (p. 16-19) whereas for more complex derivations, such as the Goldman equation, the result is simply stated. In either case the derivation is not really necessary and the reader could simply be referred to a more authoritative source. Moreover, whether stated or derived, the material is often presented in a confusing manner. Thus, for the Goldman equation (p. 7) the relationship between conductances and equilibrium potentials is not stated and the dependence of the Nernst equation on temperature is not mentioned. In the discussion of resistors the author defines (p. 17) the equivalent resistance in a circuit (R,q) and, on the following page, he changes this terminology (without any definition) to R t. As another example from this section, he discusses the problem of aliasing (p. 39) which occurs when the digitization rate is too slow for the signal frequency being digitized. However, in Fig. 4.8 he mistakenly presents, as an example of aliasing, a sine wave that has been digitized at an appropriate rate to avoid aliasing. Also, in his discussion of artifacts, he discusses the improvement in signal-to-noise that occurs with averaging (p. 81) but he fails to discuss