The evaluation of the efficacy and safety of a clinical tool, be it a
diagnostic technique, a preventive methodology, or a therapeutic
intervention, is an im- portant responsibility of physicians. The
history of medicine is characterized by the authoritarianisms of
teachers and of organizations giving way to the clinical experience of
physicians; authoritarian dictum was replaced by case report and then by
case series. As physicians learned to substitute the analysis of data
for the inconsistencies of dictums and anecdotes, the problems of the
case series as an investigative tool became more evident: patient
selection criteria, measurements of outcome, significance of results,
and extrapolation of conclusions to the community of patients. In
response to these issues, the methodology of the controlled clinical
trial has evolved and with it the instru- ments of study design and of
biostatistics as aids to study design and data analysis. The medical -
surgical armamentarium has evolved from being dependent solely upon the
observations and conclusions of a skilled clinician to being constructed
upon the systematic collection and evaluation of data by a team of
skilled clinicians and their statistical colleagues: this is the
controlled clinical trial. During the past two decades, the evaluation
of clinical approaches to pre- vention and therapy has become
particularly important to clinicians concerned with nervous system
dysfunction. There has been and continues to be an explosion of
information from the basic neurosciences and from the applica- tion of
biotechnology to the nervous system.
