Rare Treatable Neurologic Diseases

Matthew T. Lorincz, MD, PhD

John K. Fink, MD

The clinical neurologist faces a seemingly ever-expanding array of neurologic disease. Recognizing rare disorders and rare presentations of common disorders is particularly difficult. For many rare disorders, lack of clinician familiarity is a major factor in delayed diagnosis, misdiagnosis, unnecessary testing, and lack of treatment. Nonetheless, the fact that disease-altering therapy exists for some rare disorders makes their recognition essential.

This issue of Seminars in Neurology emphasizes the clinical recognition of several rare disorders for which there are specific treatments. The aim of this issue is to summarize the clinical presentation, differential diagnosis, pathogenesis, and treatment of these disorders that cannot be missed.

The disorders selected for review represent examples of categories of rare but treatable conditions. These disorders affect central nervous system, muscle, peripheral nerve, and psychiatric function and include toxic and iatrogenic disorders (calcineurin inhibitor encephalopathy, pine nut dysgeusia, and malaria prophylaxis psychosis), infectious disorders (racemose neurocysticercosis and tick paralysis), autoimmune and inflammatory disorders (stiff person syndrome, inflammatory and toxic myopathies, multifocal motor neuropathy, and Miller Fisher's syndrome), and genetic disorders (acetazolamide responsive ataxia, Wilson's disease, and late-onset Pompe's disease).

The first steps in diagnosing rare but treatable neurologic disorders are awareness of their existence and their inclusion in differential diagnostic considerations. It is our hope that clinicians will find this this issue of Seminars in Neurology useful in their recognition of these rare neurologic diseases. This issue is not meant as an exhaustive compendium of rare treatable neurologic disorders, but rather to serve as a reminder that sometimes “hoof beats” really are “zebras,” and treatable zebras at that.