Journal of Clinical Outcomes Management. 2014 June;21(6)
References
In certain situations, provocation maneuvers may be utilized in order to reproduce PNES in patients undergoing EEG monitoring. In comparison to epileptic seizures, suggestion and emotional stimuli are more likely to trigger psychogenic events [1]. Methods utilized to provoke PNES may include saline injections, placement of a tuning fork on the head or body, or even hypnosis, when a suggestion is concurrently provided that such maneuvers can trigger the patient’s seizures [1,30,31]. When evaluating seizures that are provoked in such a manner, it is important to consider whether or not the event captured is in fact a typical event for the patient, or whether the provocation has uncovered a different, atypical event. Given that PNES and epileptic seizures can co-exist within the same patient, care should be taken to avoid making a diagnosis based on capturing an atypical event, or capturing only a subset of a patient’s seizure types. This could result in failure to make an accurate and thorough diagnosis [23]. There is debate regarding the ethics of provoking seizures by way of suggestion. Some members of the epilepsy community feel that provoking seizures through suggestion is inherently deceitful, and therefore can damage the physician-patient relationship. Others assert that such provocative testing can be undertaken in an honest manner, and can ultimately help achieve an accurate diagnosis for the patient [32].
As previously mentioned, there is a proportion of patients who have co-existing epileptic seizures and PNES, and obtaining an accurate diagnosis can be especially challenging in this group. Studies have reported that around 10% to 40% of patients with PNES also have epilepsy [1,22,23,33]. Care must be taken to distinguish between differences in seizure types and if necessary, video EEG monitoring may be needed to capture both seizure types for an accurate diagnosis. This testing can then be useful in education with families and caregivers who may be shown the videos with consent from the patient in order to guide future care.
Evaluation And Diagnosis
As in much of neurology, a thorough history, along with detailed clinical observation remains essential in the diagnosis of patients with PNES and for distinguishing these events from epilepsy. Video EEG monitoring of seizures is a key adjunct to the history and clinical observation in diagnosing this condition [1,2]. Long-term video EEG monitoring is considered the “gold standard” in the characterization and differential diagnosis of seizures. Additional potentially helpful diagnostic techniques include video EEG-monitored seizure provocation, serum prolactin levels, single photon emission computed tomography, and neuropsychological testing.
Video EEG Monitoring
Video EEG monitoring, often undertaken in dedicated inpatient epilepsy monitoring units, has become a mainstay for diagnosis of psychogenic seizures. Ideally, a typical seizure is recorded with simultaneous EEG and video monitoring with no evidence of epileptic activity seen during the event. In patients with generalized convulsive epileptic seizures, the EEG should show an ictal correlate during the seizure. In the case of focal seizures with impaired awareness (complex partial seizures), the EEG will demonstrate a corresponding ictal abnormality in 85 to 95% of cases [1]. Focal seizures without impaired awareness (simple partial seizures) may not necessarily be associated with a corresponding EEG change. Up to 60% of such seizures have been shown to produce an ictal EEG abnormality, and this number may rise to almost 80% if multiple seizures are captured [34]. It is extremely important to capture a typical event with video EEG monitoring because an interictal or routine EEG may not provide all of the needed information to make a diagnosis. Specifically, a normal routine (non-ictal) EEG may be seen in epilepsy patients, and minor or non-specific abnormalities can be seen on EEGs of patients with PNES (Table 2)
