# Electrogram

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> Source: https://en.wikipedia.org/wiki/Electrogram
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{{Short description|Recording of electrical signals of body organs}}
{{Original research|date=April 2025}}

An '''electrogram''' ('''EGM''') is a recording of [electrical activity](/source/Action_potential) of [organs](/source/Organ_(biology)) such as the [brain](/source/brain) and [heart](/source/heart), measured by monitoring changes in [electric potential](/source/Voltage).<ref>{{Cite web|title=Definition of 'Electrogram'|url=https://www.collinsdictionary.com/dictionary/english/electrogram|website=[Collins English Dictionary](/source/Collins_English_Dictionary)}}</ref> Historically, it also referred to an instrument to measure atmospheric electrical potential.

==Brain==
===Electroencephalography (EEG)===
{{main|Electroencephalography}}

An electroencephalogram (EEG) is an electrical recording of the activity of the brain taken from the [scalp](/source/scalp).
An EEG can be used to diagnose [seizures](/source/Seizure), [sleep disorders](/source/Sleep_disorder), and  for monitoring of level of anesthesia during surgery.

===Electrocorticography (ECoG or iEEG)===
{{main|Electrocorticography}}

An electrocorticogram is an electrical recording of the brain measured intracranially, that is, from within the brain.<ref>{{Cite journal|last1=Dubey|first1=A.|last2=Ray|first2=S.|date=2019-05-29|title=Cortical Electrocorticogram (ECoG) Is a Local Signal|journal=Journal of Neuroscience|language=en|volume=39|issue=22|pages=4299–4311|doi=10.1523/JNEUROSCI.2917-18.2019|issn=0270-6474|pmid=30914446|doi-access=free|pmc=6538865}}</ref>

==Eye==
===Electrooculography (EOG)===
{{main|Electrooculography}}

An electrooculogram (EOG) is an electrical recording of the potential between the [cornea](/source/cornea) and the [retina](/source/retina), and does not change with [visual stimuli](/source/Stimulus_(physiology)).
An EOG can measure movements of the eyes and can help in diagnosis of [nystagmus](/source/nystagmus).

===Electroretinography (ERG)===
{{main|Electroretinography}}

An electroretinogram (ERG) is an electrical recording of the electrical activity of the retina.

==Heart==
===Electrocardiogram (ECG)===
{{main|Electrocardiogram}}

An electrocardiogram (ECG or EKG) is an electrical recording of the activity of the heart.
The typical meaning of an "ECG" is the 12-lead ECG that uses 10 wires or [electrodes](/source/Electrode) to record the signal across the chest.
Interpretation of an ECG is the basis of a number of cardiac diseases including [myocardial infarction](/source/myocardial_infarction) (heart attack) and arrhythmias such as [atrial fibrillation](/source/atrial_fibrillation).

===Cardiac electrogram===
When electrical recordings are made from the [skin](/source/skin), it is considered to be an ECG as described above.
However, electrical recordings made from within the heart such as with an [artificial cardiac pacemaker](/source/artificial_cardiac_pacemaker) or during an [electrophysiology study](/source/electrophysiology_study), the signals recorded are considered an "electrogram" instead of an ECG.
These signals are not interpreted in the same manner as an ECG.

==Other muscles==
{{main|Electromyography}}

An electromyogram (EMG) is an electrical recording of the activity of a [muscle](/source/Muscular_system) or muscle group.
An EMG study can be combined with a [nerve conduction study](/source/nerve_conduction_study) to diagnose neuromuscular diseases such as [peripheral neuropathy](/source/peripheral_neuropathy) and [amyotrophic lateral sclerosis](/source/amyotrophic_lateral_sclerosis).

==See also==
* [Radiology](/source/Radiology)

==References==
{{reflist|32em}}

==Further reading==
*{{Cite journal |last1=Reilly |first1=Richard B. |last2=Lee |first2=T. Clive |date=19 November 2010 |title=Electrograms (ECG, EEG, EMG, EOG) |journal=Technology and Health Care |volume=18 |issue=6 |pages=443–458 |doi=10.3233/THC-2010-0604 |issn=1878-7401 |pmid=21099006 }}

Category:Electrodiagnosis
Category:Electrophysiology
Category:Medical tests

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Adapted from the Wikipedia article [Electrogram](https://en.wikipedia.org/wiki/Electrogram) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Electrogram?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.