Tatum, William O.

Summary: This revision to the EEG Guidelines is an update incorporating current EEG technology and practice. “Standards of practice in clinical electroencephalography” (previously Guideline 4) has been removed. It is currently undergoing revision through collaboration among multiple medical societies and will become part of “Qualifications and Responsibilities of Personnel Performing and Interpreting Clinical Neurophysiology Procedures.” The remaining guidelines are reordered and renumbered.

Introduction:We report a unique EEG phenomenon in patients with paroxysmal neurological events undergoing video EEG monitoring.Methods:Two epilepsy centers analyzed the interictal scalp EEG in patients using personal electronic devices during epilepsy monitoring. The texting rhythm (TR) was defined as a reproducible, stimulus-evoked, generalized frontocentral monomorphic burst of 5–6 Hz theta consistently induced by active text messaging. An independent prospective and retrospective cohort was analyzed and compared from two sites in Florida and Illinois. We assessed age, gender, diagnosis, epilepsy classification, MRI, and EEG to compare patients with a TR. Analysis was performed with statistical significance set atP< 0.05.Results:We identified 24 of 98 evaluable patients with a TR in a prospective arm at one center and 7 of 31 patients in a retrospective arm at another totaling 31/129 (24.0%). The waveform prevalence was similar at both centers independent of location. TR was highly specific to active texting. A similar waveform during independent cognitive, speech or language, motor activation and audio cellular telephone use was absent (P< 0.0001). It appeared to be increased in patients with epilepsy in one cohort (P= 0.03) and generalized seizures in the other (P= 0.025). Age, gender, epilepsy type, MRI results, and EEG lateralization in patients with focal epileptic seizures did not bear a relationship to the presence of a TR in either arm of the study (P= NS).Conclusions:The TR is a novel waveform time-locked to text messaging and associated with active use of smartphones. Electroencephalographers should be aware of the TR to separate it from an abnormality in patients undergoing video EEG monitoring. Larger sample sizes and additional research may help define the significance of this unique cognitive-visual-cognitive-motor network that is technology-related and task-specific with implications in communication research and transportation safety.

The objective of this study was to identify the relationship between lambda waves (LWs) and other occipital waveforms, in a retrospective analysis of electroencephalograms (EEGs) of clinic and hospitalized patients at a single center. The LWs were correlated with α rhythm, photic driving, and positive occipital sharp transients of sleep (POSTS). A computer-generated cursor quantified amplitude and duration of POSTS and LWs (3 waveforms and both hemispheres). Fisher exact test was used for significance ( P ≤ .05). A total of 116 patients were evaluated. Of 111 patients, with interpretable results, 74 (66.67%) had visual scanning during EEG, with 37 (50.0%) having LWs. The LWs (17.69 µV) were consistently smaller than POSTS (31.40 µV) despite similar morphology. Patients with an α rhythm of >8.5 Hz were strongly correlated with the presence of LWs ( P < .0001), and those with LWs were strongly predictive of normal EEG ( P = .001). Of the 37 patients, 27 (73.0%) with LWs had photic driving ( P = .0496). No correlation was found between LWs and POSTS ( P = .45). The presence of LWs and a low normal posterior dominant rhythm (PDR) suggests intact electrocerebral health. LWs and the photic driving response suggest similar generators but stimulus-specific networks. POSTS differ from LWs despite similar morphology, suggesting different network activation of occipital generators. LWs have clinical significance in excluding encephalopathy. Occipital generators are differentiated by state and stimulus-dependent network activation and not by location and morphology.

Objective: To expand the adverse events associated with metronidazole to include nonconvulsive status epilepticus (NCSE). Design: Observational single case report of a rare association. Setting: Hospitalized lung transplant recipient treated with metronidazole for prevention of infection. Patient: A 56-year-old man with systemic symptoms, peripheral neuropathy, generalized seizure, and a subsequent acute deterioration of mental status due to NCSE. Interventions: Administration of midazolam was successful in terminating status epilepticus. Main Outcome Measures: Abrupt termination of NCSE was evident on continuous bedside electroencephalogam associated with clinical resolution of mental status. Results: Recovery occurred from NCSE eventually deteriorating to a fatal outcome. Conclusions: Metronidazole may be associated with successfully treated NCSE.