Book Review

Cerebral Dysgenesis: Embryology and Clinical Expression

N Engl J Med 1993; 329:1360October 28, 1993

Article

Cerebral Dysgenesis: Embryology and Clinical Expression
By Harvey B. Sarnat. 473 pp., illustrated. New York, Oxford University Press, 1992. $75. ISBN: 0-19-506442-9

“Exciting” is probably not the word to use in describing this 473-page clinical reference book, but it is certainly one of the first words that comes to mind. Sarnat has done what many clinicians have been saying for some time should be done: he has pulled together all the basic scientific research in the field of embryology, presented it in a manner that will be palatable to clinicians and scientists outside the field of neuroembryology, related a bewildering array of clinical entities to the neuroembryologic processes described, and presented the resulting conditions with the associated neurophysiologic and imaging data in a fashion that can be translated into day-to-day use. Sarnat states in the preface that he has tried “to convey an integrated view of the ontogenetic basis of cerebral dysgenesis in a context meaningful to medical practitioners.” He has accomplished this task with apparent ease, underscoring in doing so his depth of knowledge in this field, as well as his sensitivity to and persistent awe of the subject matter he so skillfully describes.

The initial chapter, “Substrates of Maturation in the Nervous System,” reviews in detail the neuroembryologic process from conception to birth, with a liberal sprinkling of examples of abnormalities familiar to most clinicians. This chapter sets the stage for the specific clinical conditions discussed in subsequent chapters. The photographs of embryonic tissue are clear and have been well chosen to demonstrate the points made in the text, but it is the clarity of the text that carries the reader step by step along the path of the developing nervous system. There are no apologies for incomplete knowledge in a particular area; indeed, the entire book is presented in the spirit of a science in which the current state of knowledge is always incomplete and always growing. This dual aspect is most apparent in the study of specific biochemical mechanisms of interaction among various cell types -- an area in which our understanding is partial yet the knowledge accumulated in the past two decades is most impressive.

Subsequent chapters are arranged in a logical sequence based on disturbances that occur during specific stages of the embryologic process. Terms are well defined, and a lexicon is provided in Chapter 2 to avoid any misunderstanding. Some terms, already comfortably settled in the lexicon of most readers, may have to be reconsidered -- for example, “schizencephaly,” which Sarnat notes “is ambiguous and . . . best avoided.”

The structural consequences and physiologic dysfunction related to the various dysgenetic syndromes are stressed in the more clinically oriented, later chapters. Reproductions of scans from computed tomography and magnetic resonance imaging are excellent in quality, as are the electroencephalographic examples. Photographs showing the associated subtle (and not so subtle) external dysmorphic features have been well chosen and make the point that the clinician should always take the time to look carefully at any patient with unexplained cerebral palsy and mental retardation before deciding on the sequence of investigations to be carried out.

To say the 82 pages of references are comprehensive would be an understatement. They include both historical and up-to-date material, in keeping with the structure of the book.

Although the final chapter, “Ontogeny and Phylogeny,” is more a bonus than a necessary completion of the foregoing discussion, it is a fitting conclusion to the book and takes up issues frequently left to the reader to ponder. This chapter clearly and concisely places human neuroembryogenesis within the context of science and nature as we currently understand them.

John R. Seals, M.D.
Texas Neurosciences Institute, San Antonio, TX 78229