The Electroencephalogram in Altered States of Consciousness
Neurologic Clinics August 1, 1985 DOI: 10.1016/s0733-8619(18)31025-9 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Review Peer reviewed |
|---|---|
| Population | Patients with altered states of consciousness |
| Topics | Altered states of consciousness |
| Keywords | Consciousness Electroencephalography Altered state |
| Citations | 56 |
| Key findings | EEG patterns such as diffuse slowing, triphasic waves, generalized fast activity, PLEDs, burst suppression, and alpha pattern coma can help diagnose and prognose altered states of consciousness, though they are not specific to a single etiology. |
Abstract
The EEG can be very helpful in the evaluation of patients with altered states of consciousness. Diffuse slowing of background rhythms and the presence of triphasic waves suggests metabolic dysfunction, particularly hepatic. Generalized fast activity may be seen in patients with a drug intoxication. Abnormalities, such as PLEDs or focal continual PDA, support a diagnosis of supratentorial lesion, whereas a normal appearing EEG in a comatose patient suggests a brain-stem lesion. In addition, the EEG may reveal that the alteration in consciousness is due to continual epileptic activity without motor manifestations (nonconvulsive status) that had not been suspected. As indicated, certain patterns have prognostic implications. However, as these patterns are not specific for a single etiology, the EEG is of most help when the cause is known. For example, burst suppression or a diffuse alpha pattern coma can be seen in either hypoxia or a drug intoxication. With hypoxia, these patterns carry an extremely poor prognosis for useful recovery, whereas complete recovery is often seen in cases secondary to drug ingestion. As a more extreme example, a patient whose EEG shows ECS secondary to drug intoxication may recover but will not if the ECS is due to hypoxia or severe head trauma. If the etiology of the encephalopathy is unknown, then sequential records are needed for prognosis.
Comparable studies
Other narrative reviews on altered states of consciousness, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| The Subjective Effects of Psychedelics Are Necessary for Their Enduring Therapeutic Effects. | 2020 | Review | |
| Psychobiology of Altered States of Consciousness. | 2005 | Review | |
| Intrinsic Brain Activity in Altered States of Consciousness | 2008 | Review | |
| Dynamic functional connectivity and brain metastability during altered states of consciousness | 2017 | Review | |
| A default mode of brain function in altered states of consciousness. | 2013 | Review |