Diagnostic blocks: a truth serum for malingering

Malingering is not a diagnosis. It is a behavior for which there are no established diagnostic criteria. Guidelines have been published according to which malingering might be suspected, but those guidelines do not discriminate between patients who are malingering and ones with genuine sources of chronic pain. In such patients, malingering cannot be proven, but it can be refuted if a genuine source of pain can be established. In patients with no apparent cause of pain, the source of that pain can be established using controlled diagnostic blocks. A positive response to diagnostic blocks demonstrates that the complaint of pain is genuine and, by implication, refutes any contention that the patient is malingering. When positive, diagnostic blocks provide objective data by which disputes based on opinion can be resolved, as to whether a patient is malingering or not. Negative responses do not exclude a genuine complaint of pain, for patients may have a source of pain that is not amenable to testing with diagnostic blocks. Diagnostic blocks have proved particularly useful in the investigation of spinal pain for which the cause is not evident on conventional medical imaging. They can also confirm or refute purported mechanisms of certain clinical features in complex regional pain syndromes.