Many common medications have effects on the brain and thus on the EEG. Although these effects are not specific, it is important for our readers to be familiar with them in order to avoid an erroneous diagnosis of intrinsic brain…
Indications Routine EEG Initial assessment for patients with possible epilepsy or after a seizure. If normal, depending on the level of suspicion, a repeat routine EEG, a sleep-deprived study, or a long-term EEG may be indicated. Follow-up assessment after the…
The Dementias There are many subtypes of dementias, and EEGs are nonspecific, often showing slowing of the PDR, loss of the usual anterior beta activity, and a gradual increase in diffuse slowing. Nevertheless, certain EEG features can help with our…
When evaluating a new patient, the first line of inquiry for the clinician is, “is this a seizure?” There are many seizure mimics including parasomnias, syncope, transient ischemic attacks and psychogenic non-epileptic attacks (PNEA). A seizure is defined by the…
Background Abnormalities Organization In the awake state, in a well-organized EEG, there is a well-formed posterior dominant rhythm (PDR) occipitally, which attenuates with eye opening. Anteriorly, the frequencies are faster and lower in amplitude. This is sometimes referred to as…
Neonates Neonatal EEGs are perhaps the most challenging for the student and even for the experienced electroencephalographer. In the neonatal period, the brain is developing rapidly. Within the first 24 weeks of gestation, the cortical layers of the brain form…
The Normal EEG Understanding the elements of the normal EEG is a prerequisite for developing expertise in interpreting the abnormal record. In the following discussion, the frequency bands and individual waveforms found in the normal adult EEG are described for…
Origin of the EEG The EEG records electrical activity from the cerebral cortex. Inasmuch as electrocortical activity is measured in microvolts (µV), it must be amplified by a factor of 1,000,000 in order to be displayed on a computer screen.…
Introduction The terminology for functional movement disorders (FMDs) has changed over the years. Originally called hysteria, Freud called them conversion disorders based on his view of the cause. In recent years, the term psychogenic movement disorder (PMD) was most common,…
Introduction Abnormal involuntary movements (dyskinesias) usually are caused by brain damage or dysfunction. Occasionally, however, lesions of the spinal cord, spinal roots, cervical or lumbar plexus, or even peripheral nerves appear to cause a variety of dyskinesias ( Table 26.1…