analyse_media
Reading File
Searching the Web
hydranencephaly gross pathology features cerebral hemispheres absent CSF sac
Finding Sources
Reading File
Reading File
This is a well-documented specimen. Here is a full analysis:
Gross Pathology: Hydranencephaly
What You Are Looking At
This is a brain specimen (most likely from a neonate or fetus) showing hydranencephaly - described in Bradley & Daroff's Neurology as "the most profound form of cerebral maldevelopment, in which almost all of the cerebrum is absent and replaced by a CSF-filled sac."
Structures Identified in the Image
| Structure | Appearance in Image | Status |
|---|---|---|
| Cerebral hemispheres | Large translucent, membranous fluid-filled sac (top-left) | Absent/destroyed - replaced by CSF sac |
| Leptomeninges | Thin transparent membrane forming the sac wall, with branching vessels visible | Preserved, draped over empty cavity |
| Cerebellum | Pinkish globular mass with characteristic tightly folded folia (bottom-left) | Relatively intact |
| Brainstem | Thick, cream-white cylindrical structure (right side) | Intact |
| Remnant diencephalon/basal ganglia | Lobulated pinkish tissue centrally | Partially preserved (posterior circulation territory) |
Why the Brainstem and Cerebellum Are Spared
The key pathophysiology: hydranencephaly results from bilateral internal carotid artery (ICA) occlusion in utero (typically during the second trimester, as early as week 11). This destroys the territory supplied by the anterior circulation (both cerebral hemispheres) while sparing structures fed by the posterior circulation - the vertebrobasilar system - which explains the preserved brainstem, cerebellum, thalami, and portions of the occipital/temporal lobes. - Bradley & Daroff's Neurology in Clinical Practice
Pathogenesis (from Creasy & Resnik's Maternal-Fetal Medicine)
- Bilateral ICA ischemic stroke occurs in utero
- Infarcted cerebral tissue undergoes necrosis and liquefaction
- Necrotic tissue is resorbed, leaving a cavity
- The meninges remain intact, forming a thin-walled CSF-filled cyst replacing both hemispheres
- Choroid plexuses and posterior fossa structures are typically preserved
Incidence and Etiology
- Rare: ~1-2 per 10,000 births
- Most cases are sporadic
- Causes include:
- Bilateral ICA vascular occlusion/infarction
- Intrauterine infections (CMV, toxoplasma, Zika)
- Hypoxic-ischemic insults
- Toxic/drug effects (maternal smoking implicated)
- Placental insufficiency
Differential Diagnosis
| Condition | Key Distinguishing Feature |
|---|---|
| Severe hydrocephalus | Cortical mantle is thin but present; falx intact |
| Alobar holoprosencephaly | Single monoventricle; fused thalami; absent olfactory bulbs |
| Porencephaly | Focal CSF cavity, not global; gray matter may line cleft |
| Bilateral schizencephaly | CSF-filled clefts lined by gray matter; cortex present |
MRI (in living patients) differentiates these reliably by showing absent cortical mantle with intact falx in hydranencephaly.
Associated Anomalies
- Hydrocephalus (can coexist)
- Polymicrogyria in remnant tissue
- Renal abnormalities
- Trisomy 13
- Fowler syndrome (familial form): associated with fetal akinesia, polyhydramnios, abnormal limb positioning
Prognosis
Hydranencephaly is generally incompatible with prolonged survival. Affected neonates may appear deceptively normal at birth (intact Moro reflex, cry, suck) because the brainstem is preserved. However, they lack cortical function. Most do not survive beyond the first year, though rare long-term survivors with vegetative-level function have been reported.
Syndrome associated with
Finding Sources
Searching the Web
hydranencephaly associated syndromes Fowler syndrome genetics causes
Finding Sources
Finding Sources
Reading File
Reading Web Page
https://pmc.ncbi.nlm.nih.gov/articles/PMC6014450
Here is a complete breakdown of the syndromes and conditions associated with hydranencephaly:
Syndromes Associated with Hydranencephaly
1. Fowler Syndrome (OMIM #225790) - The Most Important
Proliferative Vasculopathy and Hydranencephaly-Hydrocephaly Syndrome (PVHH)
- Inheritance: Autosomal recessive
- Gene: FLVCR2 (Feline Leukemia Virus subgroup C Receptor 2) gene mutation (homozygous or compound heterozygous)
- Mechanism: Abnormal proliferative angiopathy of small vessels throughout the brain causes destruction of cerebral tissue, resulting in hydranencephaly/hydrocephaly
- Clinical features:
- Hydranencephaly or severe hydrocephaly in utero
- Fetal akinesia (absent fetal movements)
- Multiple pterygium (joint contractures) due to akinesia
- Thick nuchal translucency on first-trimester US
- Polyhydramnios (cannot swallow due to lack of movement)
- Abnormal limb positioning
- Prognosis: Lethal - typically results in stillbirth or early neonatal death
- Source: Creasy & Resnik's Maternal-Fetal Medicine; OMIM #225790
2. Microhydranencephaly (OMIM #605013)
- Autosomal recessive
- Characterized by hydranencephaly combined with severe microcephaly
- Distinct from classic hydranencephaly where head size may be normal or macrocephalic
- Reflects a different developmental timing of the destructive insult
3. Hydranencephaly with Renal Aplasia-Dysplasia (OMIM #236500)
- Rare autosomal recessive syndrome
- Combines CNS destruction (hydranencephaly) with renal agenesis or dysplasia
- Part of the broader spectrum of cerebro-renal malformation syndromes
4. Non-Syndromic Associations
| Association | Details |
|---|---|
| Trisomy 13 (Patau syndrome) | Hydranencephaly listed as an associated anomaly; likely due to vascular dysgenesis |
| TORCH infections | CMV, toxoplasma, herpes - cause necrotizing vasculitis leading to ICA occlusion in utero |
| Twin-to-twin transfusion syndrome | Donor twin at risk for cerebral ischemia causing hydranencephaly |
| Maternal cocaine use | Vasospasm of fetal ICA |
| Maternal smoking | Implicated as a possible vascular cause |
Key Distinguishing Point
The common thread across all associated syndromes is bilateral destruction of the internal carotid artery territory - whether from genetic vasculopathy (Fowler), chromosomal anomaly (Trisomy 13), or acquired insult (infections, toxins). The posterior circulation territory (brainstem, cerebellum, thalami) is spared in all cases, as seen in the specimen image.
- Creasy & Resnik's Maternal-Fetal Medicine (OMIM #225790, #605013, #236500)
- Bradley & Daroff's Neurology in Clinical Practice
I which syndrome there is absence of carpous calosum
Finding Sources
Searching the Web
syndromes associated with agenesis of corpus callosum complete list
Reading File
Reading File
Here is a comprehensive answer on all syndromes associated with absence (agenesis) of the corpus callosum (ACC):
Syndromes with Agenesis of the Corpus Callosum
Over 200 genetic syndromes can include ACC as a feature. The most important ones are:
PRIMARY / CLASSIC SYNDROMES
| Syndrome | Key Features | Genetics |
|---|---|---|
| Aicardi Syndrome | ACC + chorioretinal lacunae + vertebral anomalies + myoclonic epilepsy + intellectual disability. Burst-suppression EEG pattern. | X-linked dominant (Xp22); almost exclusively in girls; lethal in males |
| Andermann Syndrome | ACC + intellectual disability + peripheral neuropathy (progressive sensorimotor) | Autosomal recessive (SLC12A6 gene) |
| Mowat-Wilson Syndrome | ACC + Hirschsprung disease + characteristic facies + intellectual disability | AD (ZEB2 gene) |
| Acrocallosal Syndrome (Schinzel) | ACC + polydactyly + facial dysmorphism + intellectual disability | Autosomal recessive (KIF7 gene) |
CHROMOSOMAL SYNDROMES
| Condition | Notes |
|---|---|
| Trisomy 13 (Patau) | ACC is a common midline defect |
| Trisomy 8 (Warkany) | Frequently associated with ACC |
| Trisomy 11 | ACC described as a component |
| 18p deletion | Well-documented association with ACC |
NEURODEVELOPMENTAL / METABOLIC SYNDROMES
| Syndrome | Key Features |
|---|---|
| Septo-optic dysplasia (de Morsier) | ACC + absent septum pellucidum + optic nerve hypoplasia + hypopituitarism |
| Nonketotic hyperglycinemia | ACC + severe neonatal seizures + hypotonia; ACC noted without clear explanation |
| Zellweger syndrome (cerebrohepatorenal) | ACC + peroxisomal disorder + hepatomegaly + characteristic facies |
| Tuberous sclerosis | ACC occurs as an additional anomaly in some cases |
| Fetal alcohol syndrome | Dysgenesis (partial/malformed) corpus callosum is frequently seen |
OTHER NAMED SYNDROMES
| Syndrome | Notes |
|---|---|
| Delleman syndrome (Oculocerebrocutaneous syndrome) | ACC + orbital cysts + skin appendages + brain malformations |
| Alport syndrome | ACC reported as an associated feature |
| Oro-facial-digital syndrome | ACC + oral, facial, and digital abnormalities |
| L1 syndrome (X-linked hydrocephalus) | ACC + hydrocephalus + adducted thumbs + spasticity (L1CAM mutation) |
Associated Brain Malformations (not syndromes, but commonly co-occur with ACC)
- Chiari II malformation
- Dandy-Walker malformation
- Interhemispheric lipoma (high risk of epilepsy)
- Septo-optic dysplasia
- Colpocephaly (dilatation of occipital horns - seen in ~50% of ACC cases)
- Heterotopias and polymicrogyria
Most Exam-Important Association
Aicardi syndrome is the single most tested syndrome linked to ACC:
-
Girls only (X-linked dominant, lethal in boys)
-
Classic triad: ACC + chorioretinal lacunae + infantile spasms
-
Asymmetric burst-suppression on EEG
-
Bradley & Daroff's Neurology in Clinical Practice
-
Grainger & Allison's Diagnostic Radiology
This is a shared conversation. Sign in to Orris to start your own chat.