Assessing the risk of drug-induced neurologic disorders

Clinicians are familiar with the myopathy induced by the statin class of cholesterol-lowering drugs that are now in common use. A case-control study by Gaist et al. in this issue of Neurologyshows that statins can also cause polyneuropathy.1 In itself recognition of yet another drug-induced polyneuropathy might be of little interest. But the Gaist et al. work is more generally engaging. It employs new and easily understandable methods to assess and express the risk of a drug causing neurologic side effects. Medications are responsible for a huge range of neurologic disorders, but for most such drugs we have little useful concept of risk. This makes it difficult to decide whether the neurologic disorder in a particular patient is drug-induced rather than idiopathic. If one suspects a drug side effect is due to a reversible physiologic perturbation—for instance, headache or vertigo—a trial of stopping the drug may be decisive. But no such intervention will be revealing for drugs that damage the structure of the nervous system, or permanently alter its physiology.

Our ability to obtain information about drug-induced neurologic disorders has been limited for three main reasons. First, the …