This article deals with neurological problems following the use of recreational drugs and substances as they present to neurologists. The effects of alcohol and the details of neuropsychiatric and neuropharmacological effects of recreational drugs are not considered.

CLINICAL FEATURES

It is sometimes difficult to attribute a particular clinical syndrome to a particular drug type. Certain common features emerge which may be related directly and specifically to the drug (as outlined later) but other clinical features may arise in a non-specific way from complications of injection and/or coma. Furthermore addicts may use more than one drug (wittingly or unwittingly), each of which they may describe by a variety of “street” names which are far from standard (table 1). Moreover, the dose and the constituents of what they actually take (in terms of contaminants and other substitutes) may vary according to the source, batch, etc. Lastly the effects of the drug may vary considerably according to the method of intake (orally, nasally, inhalation/smoking or by intravenous, intramuscular, or subcutaneous injection), and they may be intensified by coincidental alcohol use.

All these factors may produce a variable clinical picture which cannot be relied upon to indicate that drug abuse is the cause. Conversely and on a more practical note, the recognition of drug addiction should raise suspicion that the presenting neurological syndrome may have an unusual aetiology and pathogenesis, and be a warning for the neurologist that there is the potential for more than one pathology, and that future management may have predictable difficulties. Certain common clinical themes are useful (table 2), partly because their recognition may act as a “red flag” for drug abuse (marked with an asterisk in table 2).

WHY THINGS GO WRONG

Obviously in almost all instances of drug misuse, the …