Rare diseases · Sign or symptom
Bilateral tonic-clonic seizure
Grand mal seizures
HP:0002069
What it means
A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase.
A tonic-clonic seizure may be generalized from onset or progress from a focal seizure to a bilateral tonic clonic seizure. This term describes the observed semiology of the seizure without specifying whether the onset is focal or generalized. Thus it can be used for coding bilateral tonic-clonic seizures when the onset is not known. This form of seizure was formerly commonly called grand mal seizure.
Rare diseases that can present with this105
Very common80–99%
10- 1q44microdeletion syndrome
- Acute encephalopathy with biphasic seizures and late reduced diffusion
- Autosomal recessive frontotemporal pachygyria
- Combined oxidative phosphorylation defect type 29
- Encephalopathy due to prosaposin deficiency
- Juvenile absence epilepsy
- Myoclonic epilepsy of infancy
- Pseudoleprechaunism syndrome, Patterson type
- W syndrome
- X-linked intellectual disability, Hedera type
Common30–79%
41- Alpers-Huttenlocher syndrome
- Autosomal dominant spastic paraplegia type 6
- Bilateral parasagittal parieto-occipital polymicrogyria
- CDKL5-deficiency disorder
- Developmental and epileptic encephalopathy with spike-wave activation in sleep
- DOORS syndrome
- Early-onset epileptic encephalopathy and intellectual disability due to GRIN2A mutation
- Early-onset progressive diffuse brain atrophy-microcephaly-muscle weakness-optic atrophy syndrome
- Early-onset spastic ataxia-myoclonic epilepsy-neuropathy syndrome
- Epilepsy of infancy with migrating focal seizures
- Familial focal epilepsy with variable foci
- Fatty acid hydroxylase-associated neurodegeneration
- FOXG1 syndrome
- Gaucher disease
- Hyperphosphatasia-intellectual disability syndrome
- Infantile-onset axonal motor and sensory neuropathy-optic atrophy-neurodegenerative syndrome
- Intellectual disability-dysmorphism-hypogonadism-diabetes mellitus syndrome
- Intellectual disability-seizures-abnormal gait-facial dysmorphism syndrome
- Intellectual disability-seizures-hypophosphatasia-ophthalmic-skeletal anomalies syndrome
- Isolated permanent neonatal diabetes mellitus
- Japanese encephalitis
- Lennox-Gastaut syndrome
- Lissencephaly due to TUBA1A mutation
- MECP2-related severe neonatal encephalopathy
- Megalencephaly-severe kyphoscoliosis-overgrowth syndrome
- MELAS
- Microcephaly-intellectual disability-sensorineural hearing loss-epilepsy-abnormal muscle tone syndrome
- Mitochondrial DNA-associated Leigh syndrome
- Neurodevelopmental delay-seizures-ophthalmic anomalies-osteopenia-cerebellar atrophy syndrome
- Oliver syndrome
- PCDH19 clustering epilepsy
- Polymicrogyria with optic nerve hypoplasia
- Primary hyperaldosteronism-seizures-neurological abnormalities syndrome
- Pyruvate dehydrogenase E1-alpha deficiency
- Sandhoff disease, infantile form
- Self-limited neonatal/infantile epilepsy
- Severe Canavan disease
- Sjögren-Larsson syndrome
- Succinic semialdehyde dehydrogenase deficiency
- Unilateral hemispheric polymicrogyria
- X-linked intellectual disability-limb spasticity-retinal dystrophy-arginine vasopressin deficiency
Sometimes5–29%
28- 3-phosphoglycerate dehydrogenase deficiency, infantile/juvenile form
- 3-phosphoserine phosphatase deficiency, infantile/juvenile form
- Alternating hemiplegia of childhood
- Amish lethal microcephaly
- Angelman syndrome due to paternal uniparental disomy of chromosome 15
- Behavioral variant of frontotemporal dementia
- Bilateral generalized polymicrogyria
- Bilateral polymicrogyria
and 20 more in this range
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
Also called: Bilateral convulsive seizures · Generalised convulsion · Generalised tonic-clonic seizure (without specification of onset) · Generalized convulsion · Generalized tonic-clonic seizure (without specification of onset) · Grand mal · Seizures, tonic-clonic · Tonic-clonic convulsion
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Start free with EleplanThis 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.