Induction of psychogenic nonepileptic seizures without placebo

Patients and methods.

Results.

During the 7-month period, 21 patients with suspected psychogenic seizures were monitored. Fifty-two percent of the patients were men. Patients’ ages ranged from 19 to 66 years (mean, 36 years), and duration of PNES ranged from 5 months to 12 years (mean, 3.5 years). Two patients had spontaneous psychogenic seizures recorded, so induction was attempted in the remaining 19 patients. Induction was successful in 16 of 19 (84%) attempts. Successfully induced seizures represented habitual episodes as described in patient interviews in all cases. For the 16 successful inductions, the induction time ranged from 0.5 to 9 minutes (mean, 2.4 minutes), and 94% took less than 4 minutes.

None of the patients or their families asked about the procedure itself. All patients were referred for psychiatric evaluations. At follow-up, all patients were taking less or no antiepileptic drugs and “seizures” were significantly improved.

Discussion.

Between 39%5 and 73%6 of epilepsy centers use some sort of provocative technique to aid in the diagnosis of PNES. IV saline is probably the most commonly used method.2,4-7⇓⇓⇓⇓ Hyperventilation and photic stimulation as provocative techniques for PNES are only rarely described,4,7,8⇓⇓ and their diagnostic value has not been evaluated. The sensitivity of our provocative technique was 85%, which is comparable with other methods. For IV saline, the most commonly reported method, sensitivity ranges from 60 to 90%.2,4,7⇓⇓ Other methods, including a tuning fork4 or a patch applied to the skin,3,4⇓ report similar sensitivities. The common feature of provocative techniques for PNES is suggestion. Superficially, all techniques may appear to be comparable, and we agree that “the means of activation is not as important as the manner in which it is presented.”4,p103 However, several valid ethical arguments against placebo induction have been raised and acknowledged.5,6,8⇓⇓ Of main concern is the fact that physicians cannot honestly disclose the content of the syringe (for IV saline) or say that the maneuver (e.g., tuning fork or patch) induces seizures. Even if the term “seizures” is then used in a broader sense, encompassing PNES, a degree of disingenuousness persists. The problem is particularly acute when a placebo is used. This may result in obligatory disingenuous semantic contortions such as “normal saline may alter the salt balance in the body and make a seizure more likely to occur.”4 One major advantage of the technique described here is that hyperventilation and photic stimulation truly induce seizures, so there is no lying or deceiving. Indeed, these maneuvers are performed during most EEG studies, and most patients have undergone them previously. Thus, we feel that this technique circumvents the main concerns and objections raised against placebo provocative techniques, as pointed out by others.8 This is supported by our important finding that none of our patients or their families asked about the mechanism of the induction technique. Similarly, in a series of patients who underwent induction by a “psychiatric interview,” a technique in many ways comparable with ours, none of the patients judged the procedure as harmful and 77% viewed it as helpful.9 Specificity was not assessed in this study, as the procedure was only performed in patients with suspected PNES. Specificity could theoretically be lower for this method because, contrary to IV saline, patch, or tuning fork, photic stimulation and hyperventilation do induce epileptic seizures. However, this concern is only theoretical, because with simultaneous EEG-video monitoring it is usually easy to differentiate what was induced (i.e., an epileptic versus a nonepileptic event). If a nonepileptic event was induced, it is clear that suggestion was the principal factor, rather than hyperventilation or photic stimulation. If an absence, myoclonic, or generalized tonic-clonic seizure (usually in the context of an idiopathic generalized epilepsy) was induced, it would be easy to recognize. Thus, we agree with others4 that provocative techniques should only be performed with EEG-video monitoring.

Provocative techniques can be extremely useful for the diagnosis of PNES, particularly when the diagnosis remains uncertain and no spontaneous attacks occur in the epilepsy monitoring unit. When carefully studied, using simultaneous EEG, the specificity of provocative techniques approaches 100%.3,8⇓ Such techniques are also useful in other psychogenic symptoms. Suggestibility is a feature of somatoform disorders at large. For example, in psychogenic movement disorders, in which the diagnosis rests solely on phenomenology (i.e., no help from EEG), response to placebo or suggestion is considered an important diagnostic criterion for definite psychogenic mechanism.10 In addition, there is a strong economic argument for the use of these techniques, especially with the constraints imposed by third-party payers. When spontaneous attacks do not occur, the evaluation is inconclusive. Thus, provocative techniques often turn an inconclusive evaluation into a diagnostic one.

Because this technique overcomes the main ethical limitations and concerns of placebo techniques5,6,8⇓⇓ without compromising its diagnostic value, we believe that it should be the technique of choice. The sensitivity is comparable with other provocative methods, and the specificity is, like other techniques, extremely high, provided that it is used only with EEG-video monitoring. Without the use of a placebo, this provocative technique is analogous to other clinical maneuvers (e.g., Hoover’s maneuvers for leg weakness) performed during the neurologic examination when nonorganic symptoms are suspected.7