Rare diseases · Sign or symptom

Low voltage EEG

HP:0011181

What it means

EEG with an amplitude less than 30 microvolts without observable occipital alpha rhythm (8-13 Hz).

A low voltage EEG is a rare finding but not generally pathologic.

Rare diseases that can present with this1

Sometimes5–29%

1

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

EEG with constitutional variants
Low voltage EEG

Tracking symptoms like this for someone? Eleplan keeps symptoms, diagnoses, medications and every specialist in one plan.

Start free with Eleplan

This page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.