Plain-language definitions
Glossary
Clear definitions of terms you may meet in reports and appointments. This is educational and does not replace your clinician's explanations.
A
- Antiseizure medicine (ASM)
- A medicine used to reduce or prevent seizures. Also called an antiepileptic drug (AED).
- Antisense oligonucleotide (ASO)
- A small piece of synthetic genetic material given (usually into spinal fluid) to adjust how a gene is read — used in several emerging epilepsy therapies.
- Ataxia
- Unsteady, poorly coordinated movement or balance, often affecting walking.
- Atonic seizure
- A seizure with sudden loss of muscle tone, which can cause a fall ('drop attack').
- Augmentative and alternative communication (AAC)
- Tools and methods — from picture boards to speech-generating devices — that support or replace spoken language.
- Autism spectrum disorder (ASD)
- A neurodevelopmental condition affecting social communication, with focused interests and sensory differences.
C
- Comorbidity
- A condition that occurs alongside the main condition (for example sleep problems alongside epilepsy).
D
- Developmental and epileptic encephalopathy (DEE)
- A condition where both frequent seizures and the underlying brain difference affect development.
- Dyskinetic
- Describing involuntary, often writhing or jerky movements (a type of cerebral palsy).
- Dystonia
- Sustained or repetitive muscle contractions causing twisting postures or abnormal positions.
E
- EEG (electroencephalogram)
- A painless test that records the brain's electrical activity, used to study seizures.
- Epileptic spasm
- A brief, sudden stiffening or jackknife movement, usually in clusters; the seizure type in West syndrome.
F
- Focal seizure
- A seizure that begins in one part of the brain (as opposed to generalized).
G
- Gain-of-function variant
- A genetic change that makes a protein or channel overactive. The opposite of loss-of-function.
- Generalized seizure
- A seizure that involves both sides of the brain from the start.
- GMFCS
- Gross Motor Function Classification System — levels I–V describing mobility in cerebral palsy.
H
- Hypotonia
- Low muscle tone — a 'floppy' feel — which can affect movement and feeding.
- Hypoxic–ischaemic encephalopathy (HIE)
- Brain injury in a newborn caused by reduced oxygen or blood flow around the time of birth.
- Hypsarrhythmia
- A chaotic, high-amplitude EEG pattern seen in West syndrome.
I
- Intrathecal
- Given into the fluid around the spinal cord (for example an intrathecal baclofen pump, or some gene therapies).
K
- Ketogenic diet
- A medically supervised high-fat, low-carbohydrate diet used to treat drug-resistant epilepsy.
L
- Loss-of-function variant
- A genetic change that reduces or removes a protein's normal activity. The opposite of gain-of-function.
M
- Myoclonic seizure
- A seizure causing brief, shock-like muscle jerks.
N
- Neurodevelopmental disorder
- A condition affecting how the brain develops, influencing movement, learning, communication or behaviour.
P
- Parasomnia
- An unusual event during sleep, such as sleepwalking or night terrors.
- Precision (personalised) medicine
- Treatment guided by the specific cause — often a genetic change — in an individual.
S
- Spasticity
- Increased muscle tone causing stiffness, common in cerebral palsy.
- Status epilepticus
- A seizure that lasts a long time (or repeated seizures without recovery) — a medical emergency.
- Stereotypy
- A repetitive, purposeless movement such as hand-flapping or rocking.
T
- Tic
- A sudden, repetitive movement or sound that is largely involuntary.
- Tone (muscle tone)
- The resting tension in muscles; can be increased (spasticity/dystonia) or decreased (hypotonia).
V
- Vagus nerve stimulation (VNS)
- A device that stimulates a nerve in the neck to help reduce seizures.
Zatay Medical provides independent educational reviews only. Our reports are not a diagnosis, treatment, or prescription, and do not replace care from your treating physician.