The aetiology of psychogenic non‐epileptic seizures: risk factors and comorbidities

Psychogenic non‐epileptic seizures (PNES), also known as dissociative seizures, are paroxysms of altered subjective experience, involuntary movements and reduced self‐control that can resemble epileptic seizures, but have distinct clinical characteristics and a complex neuropsychiatric aetiology. They are common, accounting for over 10% of seizure emergencies and around 30% of cases in tertiary epilepsy units, but the diagnosis is often missed or delayed. The recently proposed “integrative cognitive model” accommodates current research on experiential, psychological and biological risk factors for the development of PNES, but in view of the considerable heterogeneity of presentations and medical context, it is not certain that a universal model can capture the full range of PNES manifestations. This narrative review addresses key learning objectives of the ILAE curriculum by describing the demographic profile, common risk factors (such as trauma or acute stress) and comorbid disorders (such as other dissociative and functional disorders, post‐traumatic stress disorder, depressive and anxiety disorders, personality disorders, comorbid epilepsy, head injury, cognitive and sleep problems, migraine, pain, and asthma). The clinical implications of demographic and aetiological factors for diagnosis and treatment planning are addressed.     

Assessing quantitative EEG spectrograms to identify non‐epileptic events

Aims. To evaluate the sensitivity and specificity of quantitative EEG (QEEG) spectrograms in order to distinguish epileptic from non‐epileptic events. Methods. Seventeen patients with paroxysmal non‐epileptic events, captured during EEG monitoring, were retrospectively assessed using QEEG spectrograms. These patients were compared to a control group of 13 consecutive patients (ages 25‐60 years) with epileptic seizures of similar semiology. Assessment of raw EEG was employed as the gold standard against which epileptic and non‐epileptic events were validated. QEEG spectrograms, available using Persyst 12 EEG system integration software, were each assessed with respect to their usefulness to distinguish epileptic from non‐epileptic seizures. The given spectrogram was interpreted as indicating a seizure if, at the time of the clinically identified event, it showed a visually significant change from baseline. Results. Eighty‐two clinically identified paroxysmal events were analysed (46 non‐epileptic and 36 epileptic). The “seizure detector trend analysis” spectrogram correctly classified 33/46 (71%) non‐epileptic events (no seizure indicated during a clinically identified event) vs. 29/36 (81%) epileptic seizures (seizure indicated during a clinically identified event) (p=0.013). Similarly, “rhythmicity spectrogram”, FFT spectrogram, “asymmetry relative spectrogram”, and integrated‐amplitude EEG spectrogram detected 28/46 (61%), 30/46 (65%), 22/46 (48%) and 27/46 (59%) non‐epileptic events vs. 27/36 (75%), 25/36 (69%), 25/36 (69%) and 27/36 (75%) epileptic events, respectively. Conclusions. High sensitivities and specificities for QEEG seizure detection analyses suggest that QEEG may have a role at the bedside to facilitate early differentiation between epileptic seizures and non‐epileptic events in order to avoid unnecessary administration of antiepileptic drugs and possible iatrogenic consequences.     

Evoked and psychogenic epileptic seizures. I. Precipitation

The precipitation of seizures by external stimulation (evoked seizures) is well known. Less well known is the precipitation of seizures by a change in the patient's thinking or feelings. This artick uses Lockhart's monkey model of focal epilepsy to propose that there is a close relationship between seizures and ongoing brain activity. Thus, seizures precipitated by both voluntary and spontaneous changes in behaviour and thinking must commonly occur. Clinical examples of such seizure precipitation is described.     

Self‐induction seizures in sunflower epilepsy: a video‐EEG report

Seizures triggered by visual stimuli are the most common type of reflex seizure. Self‐induced seizures produced by stimulation of natural light are rare and self‐induction is a mode of seizure precipitation employed by either intellectually disabled or healthy photosensitive individuals. Absences and myoclonic jerks are the most common seizure types in self‐induction. We report on a girl with normal intelligence who self‐induced seizures by waving her outspread fingers in front of a bright light. This situation is called sunflower epilepsy. [Published with video sequences]     

Electropositive seizures and non‐convulsive status epilepticus in a critically ill patient with prior skull defect

Epileptiform discharges captured on routine scalp EEG typically carry a surface negative dipole. We present a patient whose continuous EEG recording in the intensive care setting captured frequent electropositive non‐convulsive seizures. Epileptiform discharges with positive polarity are common in the pediatric population but have rarely been reported in adult patients. When reported in adults, such patients usually have skull defects. As surface positive discharges are scarce, adult electroencephalographers should be prudent to differentiate such discharges from artifact, particularly in an intensive care setting where EEG artifact is common.     

Genetic factors in epileptic seizures: evidence from a large twin population

The Finnish Twin Cohort study (27776 individuals; all twins of the same sex born before 1958 and alive in 1967) detected 316 cases of epileptic seizures occurring in 310 twin pairs: 89 monozygotic pairs and 221 dizygotic pairs, including three concordant monozygotic pairs and three concordant dizygotic pairs. The ratio of the observed to expected number of concordant pairs for epileptic seizures was 5.48 (90% CL 1.5–14.2) in monozygotic and 2.12 (90% CL 0.6–5.5) in dizygotic pairs. The results suggest that 8% to 27% of the incidence of epileptic seizures is related to genetic variability. The study of environmental differences in discordant monozygotic pairs should provide insights into the etiology of this group of disorders.     

Cerebrospinal fluid findings after epileptic seizures

We aimed to evaluate ictally‐induced CSF parameter changes after seizures in adult patients without acute inflammatory diseases or infectious diseases associated with the central nervous system. In total, 151 patients were included in the study. All patients were admitted to our department of neurology following acute seizures and received an extensive work‐up including EEG, cerebral imaging, and CSF examinations. CSF protein elevation was found in most patients (92; 60.9%) and was significantly associated with older age, male sex, and generalized seizures. Abnormal CSF‐to‐serum glucose ratio was found in only nine patients (5.9%) and did not show any significant associations. CSF lactate was elevated in 34 patients (22.5%) and showed a significant association with focal seizures with impaired consciousness, status epilepticus, the presence of EEG abnormalities in general and epileptiform potentials in particular, as well as epileptogenic lesions on cerebral imaging. Our results indicate that non‐inflammatory CSF elevation of protein and lactate after epileptic seizures is relatively common, in contrast to changes in CSF‐to‐serum glucose ratio, and further suggest that these changes are caused by ictal activity and are related to seizure type and intensity. We found no indication that these changes may have further‐reaching pathological implications besides their postictal character.     

Flexible dosing of adjunctive zonisamide in the treatment of adult partial‐onset seizures: a non‐comparative,open‐label study (ZEUS)

Dupont S, Striano S, Trinka E, Springub J, Giallonardo AT, Smith P, Ellis S, Yeates A, Baker G. Flexible dosing of adjunctive zonisamide in the treatment of adult partial‐onset seizures: a non‐comparative, open‐label study (ZEUS).
Acta Neurol Scand: 2010: 121: 141–148.
© 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Objectives – To assess the efficacy and tolerability of zonisamide in a study allowing flexible dosing in a more diverse and less refractory population than assessed in randomized controlled trials. Methods – This 19‐week, non‐comparative study of adjunctive zonisamide included 281 adults who had at least four partial‐onset seizures within 8 weeks on one or two antiepileptic drugs. Alterations to zonisamide doses were allowed after titration, except during two fixed‐dose periods (weeks 10–13 and 16–19). Results – At the end of the second fixed‐dose period (median dose 300 mg/day), the median reduction in monthly seizure frequency was 33.3–41.1%; ≥50% responder rate was 40.9–44.2%; and seizure freedom rate was 15.0–15.9%, depending on the analysis used. The most common adverse events were fatigue (16.7%) and somnolence (15.3%). Conclusions – Zonisamide demonstrated efficacy in a setting more reflective of clinical practice and was generally well tolerated.     

Paroxysmal non‐epileptic events in infancy: five cases with typical features

The differential diagnosis of paroxysmal non‐epileptic events in early childhood is one of the most challenging tasks in paediatrics, and may be difficult even for specialized child neurologists. Parents are usually concerned by every unusual movement of their children and consult paediatric general practitioners immediately. We investigated five infants/toddlers (aged 1–30 months) referred by their general practitioners with a suspicion of epilepsy. None of them were ultimately shown to have epilepsy. Our aim was to determine the main reasons for referral and describe, through images and video, the typical features of five non‐epileptic paroxysmal events (benign neonatal sleep myoclonus, jitteriness, shuddering attack, paroxysmal tonic upgaze, and infantile masturbation). The review of these events reveals the significance of the circumstances within the history of the patients. A detailed history is of considerable help in the differentiation of epileptic paroxysmal events from non‐epileptic events, avoiding unnecessary investigations. Video‐EEG examination is necessary only in cases when epilepsy is strongly suspected. [Published with video sequences].