ORPHA:86908
Hemiconvulsion-hemiplegia-epilepsy syndrome
Also known as: IHHS · HHE · HHE syndrome
Query health: suspect — Only one of 2 strategies returned hits (phrase).
Publications
463
82.6th percentile
Trials
0
Interventional, condition-specific
Researchers
1,320
Distinct authors in sample
Gene link
—
Readiness
2/6
Stages with a signal
Clinical definition (Orphanet)
A rare childhood-onset syndrome characterized by hemiplegia occurring in children (typically under the age of 4) following prolonged focal , often febrile in nature. The condition progresses through three stages: initial prolonged , subsequent hemiplegia (weakness or paralysis on one side of the body), and eventual , following a latent period. The condition may be or associated with structural, infectious, traumatic, or degenerative brain abnormalities. Patients present with acute unilateral brain swelling, followed by cerebral hemiatrophy. Inflammation, genetic predisposition, and prolonged seizure activity may play a role in the disease development/progression.
Cross-references
Joined from Mondo / Orphanet. MeSH labels may enter searches; UMLS / OMIM / NCIT are stored for reference.
- MONDO:0019485
- UMLS:C0549118
Additional Mondo synonyms (1)
hemiconvulsion-hemiplegia-epilepsy syndrome
Research stages
Trial readiness signals
Where this condition sits on an open-data research pipeline — not how close a treatment is, and not medical advice. Empty stages often mean “not in these databases under this Mondo ID,” not “impossible.”
2/6 stages with a signal
No specific-condition interventional trial, but broader-category trials exist — discuss eligibility with a clinician.
- Gene identifiedNot found
No GenCC disease–gene assertion in this build
- LiteraturePresent
463 matched papers (261 in last 10 years) Source
- Phenotype characterisedNot checked
Not yet enriched from Monarch / HPO
- Animal modelNot checked
Not yet enriched from Monarch / Alliance
- Orphan designationNot checked
FDA/EMA orphan-drug designation not enriched yet
- Interventional trialPartial
None under the specific name; 1 for broader category epilepsy syndrome
Biology
Genes and phenotypes
Gene–disease validity from GenCC, plus phenotypes and animal models joined from Monarch Initiative via Mondo ID — not a clinical diagnosis aid.
Do we know what causes it?
Not yet — the cause hasn't been pinned down in GenCC.
No strong gene–disease assertion joined for this Orphanet entity.
Phenotypes (Monarch / HPO)
Not enriched in this build — Monarch phenotype joins were not run for this record.
Animal models (Monarch / Alliance)
Not enriched in this build.
Literature
Is anyone studying this?
463
463 papers have ever been published on this condition (under this name). For scale, breast cancer has over 700,000. Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=5449) is 41.
463 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 41 (publications denominator n=5449).
261 in the last 10 years · medium confidence · 82.6th percentile (publications denominator)
Phrase hits: 463 · MeSH hits: 0
Who's working on it?
1,320
Distinct author names in 200 sampled papers — named people below.
Who's working on it?
No interventional trial matched this name; these authors publish on it in the sampled literature — a practical starting point for contact.
- 01Nabbout R4 papers · 2025
Reference Center for Rare Epilepsies, Department of Pediatric Neurology, Necker-Enfants Malades Hospital, Assistance Publique Hôpitaux de Paris, University Paris Cité, Member of ERN EpiCARE, Paris, France.
Papers in Europe PMC - 02Sharma S4 papers · 2022
Department of Social & Preventive Medicine Dayanand Medical College Ludhiana India.
Papers in Europe PMC - 03Takanashi JI4 papers · 2025
Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Yachiyo, Japan.
Papers in Europe PMC - 04Zhang Y4 papers · 2026
Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Papers in Europe PMC - 05Auvin S3 papers · 2022
Department of Pediatric Neurology, University Hospital, Lille, France. auvin@invivo.edu
Papers in Europe PMC - 06Maegaki Y3 papers · 2025
Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan. Electronic address: maegaki@med.tottori-u.ac.jp.
Papers in Europe PMC - 07Sankhyan N3 papers · 2022
Pediatric Neurology Unit, Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
Papers in Europe PMC - 08Uldall P3 papers · 2014Papers in Europe PMC
- 09Alekseeva TM2 papers · 2021
Almazov National Medical Research Center, St. Petersburg, Russia.
Papers in Europe PMC - 10Assadeck H2 papers · 2019
Department of Neurology National Hospital of Niamey Niamey Niger.
Papers in Europe PMC
Clinical research
Is a treatment being tested?
0
interventional trials for this specific condition
No interventional trial testing a treatment matched this specific condition name on ClinicalTrials.gov (observational studies and pan-disease registries are listed separately when present). 1 trial are registered for epilepsy syndrome, the broader category — shown separately because they may or may not enrol this specific subtype.
Data as of 27 July 2026
No matched interventional trials. This is true for 73% of diseases in the trials denominator (5114 of 7003). Here are the researchers publishing on it.
medium confidence · 36.5th percentile (trials denominator)
Recruiting interventional trials
From the matched ClinicalTrials.gov set
No interventional trial testing a treatment was found for this specific condition name on ClinicalTrials.gov.
1 interventional trial matched epilepsy syndrome, the broader category — listed below. Those studies are not counted in the condition-specific total.
Broader category: epilepsy syndrome
1
Interventional trials for the parent category, exclusive of NCT IDs already counted above. Eligibility for this subtype is not guaranteed.
Worth raising with a clinician. How we count trials.
Recruiting under the broader category
- NCT07281027·NOT YET RECRUITING·COMparison Between Anakinra and Tocilizumab in NORSE - "COMBAT-NORSE"
Conditions: New Onset Refractory Status Epilepticus · New-Onset Refractory Status Epilepticus · Febrile Infection-Related Epilepsy Syndrome (FIRES)·Matched via name phrase
Where to find support
We do not yet link condition-specific patient organisations. These umbrella groups support undiagnosed and ultra-rare families:
India — NPRD
Last verified 2026-07-26This ORPHAcode is not on our curated NPRD list (direct or Mondo-parent match). That does not decide clinical eligibility; families in India should ask a notified Centre of Excellence about current coverage.
Hand-curated for this project. ORPHAcode mappings are best-effort and may be incomplete or imprecise for umbrella categories. Parent (Mondo) matches mean the policy lists a broader category — confirm eligibility with a Centre of Excellence. Financial entitlements summarised from public policy statements and may change. This is not official government guidance.
How we counted this
Europe PMC query (preferred label + any corrected label + Orphanet and Mondo exact synonyms, stoplisted; unioned with resolved MeSH labels when available). UMLS / OMIM / NCIT cross-references are stored on the overview but are not added to the query string.
"Hemiconvulsion-hemiplegia-epilepsy syndrome" OR "HHE syndrome"
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Hemiconvulsion-hemiplegia-epilepsy syndrome" OR "HHE syndrome" OR "childhood-onset epilepsy syndrome with developmental and/or epileptic encephalopathy" OR "childhood-onset epilepsy syndrome"
Recall-expansion terms: childhood-onset epilepsy syndrome with developmental and/or epileptic encephalopathy, childhood-onset epilepsy syndrome
Study-type breakdown: 0 interventional · 0 observational · 0 expanded access. Only interventional studies enter the trial headline.
Parent-category trials query:
"epilepsy syndrome"
Query health: suspect — strategies attempted: phrase, recall-expansion; with hits: phrase
Run this search on ClinicalTrials.gov
Synonyms dropped by stoplist: IHHS; HHE
Confidence reasoning
- Preferred label is multi-word and distinctive
- 2 synonym(s) dropped by stoplist (may under-count)
- No label/synonym collisions with other diseases in this corpus
Ingested 2026-07-27T03:19:27.264Z