Randomized controlled trials play an ever-increasing role in therapeutic decisions. Claims for the effectiveness of a particular therapy based on statistical analysis of large-scale clinical studies must be treated circumspectly. Was the study well conceived as reflected in a clearly stated hypothesis and outcome criteria; was there adherence to the plans for randomization and admission of cases into the study; were the statistical methods appropriate; and were the controls truly comparable? It has been our experience that the original results must be accepted with caution and it is prudent to wait until further studies confirm the benefits that have been claimed.
There are, of course, many instances in which evidence is not available or is not applicable to difficult individual therapeutic decisions. This is in part true because small albeit statistically significant effects in large groups may be of little consequence when applied to an individual patient. It goes without saying that data derived from trials must be used in the context of a patient’s overall physical and mental condition and age. Furthermore, for many neurologic conditions there is, at the moment, inadequate evidence on which to base treatment. Here, the physician makes judgments based on partial or insufficient data. Even deciding purposefully to wait before committing to an intervention displays wisdom.
Even when no effective treatment is possible, neurologic diagnosis is more than an intellectual pastime. The first step in the scientific study of any disease process is its identification in the living patient.
In closing this introductory chapter, a comment regarding the extraordinary burden of diseases of the nervous system is appropriate. It is not just that conditions such as brain and spinal cord trauma, stroke, epilepsy, developmental delay, psychiatric diseases, and dementia are ubiquitous, but that these are highly disabling and often chronic in nature, altering in a fundamental way the lives of affected individuals. Furthermore, the promise of cure or amelioration by new techniques such as molecular biology, genetic therapy, and brain–computer interfaces has excited vast interest, for which reason aspects of the current scientific insights are included in appropriate sections of the book.
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