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Ventricular system

The ventricular system is a network of four interconnected cavities within the brain that are filled with cerebrospinal fluid (CSF), serving as a protective reservoir that cushions the neural tissue, facilitates nutrient transport, and aids in waste removal.^[1]^[2] This system originates from the lumen of the embryonic neural tube and consists of the two lateral ventricles, the third ventricle, and the fourth ventricle, all lined by ependymal cells that contribute to CSF dynamics.^[3] The total CSF volume within the ventricles accounts for approximately 20-25 mL in adults, representing about 20% of the overall CSF in the central nervous system.^[3] The lateral ventricles, one in each cerebral hemisphere, are the largest components and exhibit a C-shaped configuration with a body and three horns (anterior, posterior, and inferior).^[1] They connect to the narrow, slit-like third ventricle—situated in the diencephalon between the thalami—via the paired interventricular foramina of Monro.^[2] The third ventricle, in turn, links to the fourth ventricle through the cerebral aqueduct of Sylvius, a narrow channel traversing the midbrain.^[1] The fourth ventricle, located in the hindbrain between the pons, medulla oblongata, and cerebellum, narrows inferiorly into the central canal of the spinal cord and communicates with the subarachnoid space via the foramina of Luschka (lateral) and Magendie (median).^[3] These connections enable the unidirectional flow of CSF from its production sites to its absorption pathways.^[2] CSF is primarily produced by the choroid plexus, a specialized vascular tissue present in the lateral, third, and fourth ventricles (though absent in certain horns and the aqueduct), at a rate of about 500 mL per day in adults, with only a small fraction (~150 mL) circulating at any time.^[1] This fluid not only provides mechanical protection against trauma but also maintains intracranial pressure homeostasis and supports metabolic functions by circulating through the ventricular system into the subarachnoid space, where it is reabsorbed via arachnoid granulations into the venous bloodstream.^[3] Disruptions in this system, such as obstructions leading to hydrocephalus, can cause ventricular enlargement and elevated intracranial pressure, underscoring its critical role in neurological health.^[2]

Anatomy

Lateral ventricles

The lateral ventricles are paired, C-shaped cavities located within each cerebral hemisphere, specifically one in each telencephalon, forming the largest components of the brain's ventricular system.^[1]^[4] These structures consist of a central body and three horns: the anterior horn, which extends into the frontal lobe; the body, which runs along the inferior aspect of the corpus callosum in the parietal lobe; the posterior horn, which projects into the occipital lobe; and the inferior horn, which extends into the temporal lobe and is the longest of the horns.^[1]^[4] An atrium, or trigone, serves as a triangular junction connecting the body to the occipital and temporal horns.^[4] Internally, the lateral ventricles are lined by a thin layer of ependymal cells that form the ependyma, providing a smooth, impermeable barrier.^[1] The choroid plexus, a vascular fringe of tissue, invaginates into the ventricles through the choroidal fissure, with a prominent aggregation known as the glomus located in the atrium.^[4]^[1] The two lateral ventricles are separated medially by the septum pellucidum, a thin, vertical sheet composed of two closely apposed laminae covered by ependyma on their ventricular surfaces.^[4]^[1] In adults, each lateral ventricle has an approximate volume of 7 to 10 mL, though this can vary with age, sex, and pathological conditions such as brain atrophy, which may lead to enlargement and altered shape, or compensatory changes in horn prominence.^[1]^[4] For instance, the occipital horn exhibits notable variability in size and may even be absent in some individuals without clinical significance.^[4] The lateral ventricles are closely related to several key subcortical structures. The caudate nucleus forms the lateral wall of the anterior horn, body, and tail of the inferior horn.^[1]^[4] The thalamus contributes to the floor of the body and the roof of the temporal horn, while the fornix outlines the medial and inferior aspects of the anterior horn and body, as well as the roof of the choroidal fissure.^[1]^[4] The corpus callosum roofs the anterior horn and body, and the tapetum, a fiber bundle from the corpus callosum, forms the roof and lateral wall of the posterior and inferior horns.^[1] The lateral ventricles communicate with the third ventricle through the paired interventricular foramina of Monro.^[1]^[4]

Third ventricle

The third ventricle is a narrow, slit-like cavity situated in the midline of the diencephalon, positioned between the two thalami and above the hypothalamus. It forms a central, unpaired compartment of the ventricular system, contrasting with the paired lateral ventricles in the cerebral hemispheres. This structure communicates with the lateral ventricles via the interventricular foramina (foramina of Monro), allowing passage of cerebrospinal fluid (CSF).^[1] The boundaries of the third ventricle are well-defined and contribute to its anatomical integration with surrounding diencephalic structures. The roof consists of a thin ependymal sheet overlying the tela choroidea, which contains choroid plexus responsible for CSF production. The floor is formed by components of the hypothalamus, including the optic chiasm anteriorly, the tuber cinereum and infundibulum centrally, and the mammillary bodies and posterior perforated substance posteriorly. The anterior wall is composed primarily of the lamina terminalis, along with the anterior columns of the fornix and the anterior commissure. The posterior wall includes the pineal gland superiorly, the posterior commissure, and the opening to the cerebral aqueduct inferiorly. Laterally, the walls are formed by the medial surfaces of the thalami superiorly and the hypothalamus inferiorly, separated by the hypothalamic sulcus; in approximately 70% of adult brains, a midline adhesion known as the massa intermedia bridges the thalamic surfaces within the ventricle.^[1] Extending from the main cavity are several recesses that protrude into adjacent structures, enhancing the ventricle's three-dimensional configuration. The infundibular recess projects inferiorly into the infundibulum of the hypothalamus, just above the pituitary stalk. The optic recess extends anteriorly toward the optic chiasm, while the pineal recess reaches posteriorly into the stalk of the pineal gland. These recesses, typically measuring 2-3 mm in depth, are lined by ependyma and vary slightly in prominence among individuals.^[1] In adults, the third ventricle measures approximately 2.5 cm in anteroposterior length, with a variable transverse width of 0.5-1.5 cm and a superoinferior height of about 0.5 cm, though these dimensions can enlarge slightly with age and show individual variability influenced by cranial morphology.^[5]^[6]

Fourth ventricle

The fourth ventricle is a diamond-shaped cavity in the hindbrain, positioned between the pons and the upper medulla oblongata anteriorly and the cerebellum posteriorly.^[1] It extends from the cerebral aqueduct superiorly to the central canal of the spinal cord inferiorly, forming a tent-like space filled with cerebrospinal fluid.^[7] In adults, it measures approximately 3 cm in length and up to 2 cm in width at its broadest point.^[8] The roof of the fourth ventricle is formed by the thin superior medullary velum anteriorly, the cerebellar vermis centrally, and the inferior medullary velum posteriorly, with the choroid plexus confined to this roof within the tela choroidea.^[1] The floor consists of the rhomboid fossa on the dorsal surface of the pons and upper medulla, divided by a median sulcus into symmetrical halves that include the superior and inferior fossae as well as the vagal and hypoglossal trigones.^[1] Laterally, the ventricle is bounded by the cerebellar peduncles and features recesses that extend outward.^[7] Cerebrospinal fluid exits the fourth ventricle through the median aperture, known as the foramen of Magendie, located at its inferior end in the midline, and the paired lateral apertures, or foramina of Luschka, at the distal ends of the lateral recesses.^[9] Internally, the obex marks the caudal tip where the taeniae fornicis converge, forming a small fold at the transition to the central canal.^[1]

Connecting pathways

The connecting pathways of the ventricular system consist of the interventricular foramina and the cerebral aqueduct, which link the ventricles to facilitate continuity throughout the brain's internal fluid spaces.^[1] The interventricular foramina, also known as the foramina of Monro, are paired openings that connect each lateral ventricle to the third ventricle.^[1] These foramina are located in the superoanterior portion of the third ventricle, anterior to the thalami and at the anterior limit of the thalamic structures.^[10] Each foramen measures approximately 3-4 mm in diameter and serves as a narrow passage bounded medially by the thalamus and laterally by the lateral ventricle wall.^[1] The cerebral aqueduct, or aqueduct of Sylvius, is a slender channel that connects the third ventricle to the fourth ventricle.^[11] It extends approximately 15 mm in length with a diameter of 1-2 mm, coursing through the midbrain tegmentum and surrounded by the periaqueductal gray matter.^[11] This pathway is vulnerable to compression by nearby tumors, such as tectal plate gliomas or pineal region masses, which can narrow its lumen and disrupt ventricular communication.^[11] Both the interventricular foramina and the cerebral aqueduct are lined by ciliated ependymal cells, forming a simple cuboidal to columnar epithelium without choroid plexus tissue.^[11] These ependymal-lined channels maintain the structural integrity of the ventricular system, enabling seamless passage between its components.^[1]

Development

Embryonic origins

The ventricular system originates from the lumen of the neural tube, which forms during the process of neurulation in the early embryonic period. By the end of the fourth week of gestation, the neural tube closes, establishing a continuous cavity that will differentiate into the ventricular spaces and central canal of the spinal cord.^[1] At this stage, the rostral portion of the neural tube expands and constricts to form three primary brain vesicles: the prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain).^[1] These vesicles represent the foundational structures from which the ventricular system emerges, with their lumens serving as the precursors to the mature cavities.^[12] The lateral ventricles derive from the telencephalic vesicles, which arise as secondary outgrowths of the prosencephalon through evagination of the telencephalon walls.^[4] This evagination process involves outward bulging of the neuroepithelium, creating paired cavities that expand to form the lateral ventricles within the developing cerebral hemispheres.^[12] The third ventricle originates from the diencephalon, another secondary derivative of the prosencephalon, where cavitation and expansion of the diencephalic cavity establish its midline position between the thalami.^[13] In contrast, the fourth ventricle develops from the rhombencephalon, specifically its myelencephalic portion, as the hindbrain vesicle elongates and its lumen widens to accommodate the pons and medulla.^[1] Key developmental processes include the separation of the ventricular lumen from the amniotic fluid following neural tube closure and the subsequent inflation of these spaces by embryonic cerebrospinal fluid.^[12] The choroid plexus begins to form through invagination of the vascularized pia mater into the ventricular walls, starting around the sixth week of gestation in the fourth ventricle and extending to the lateral ventricles by the seventh week.^[14] This structure arises from specialized ependymal cells and vascular elements, marking the onset of cerebrospinal fluid production within the ventricles.^[1] By the eighth week, the basic outlines of the ventricular system are established, with the lateral ventricles adopting a C-shaped configuration and the third and fourth ventricles displaying their characteristic midline and rhomboid shapes, respectively.^[14] This timeline aligns with the transition from the embryonic to the fetal period, setting the stage for further refinement of the system.^[4]

Postnatal maturation

At birth, the lateral ventricles have an average volume of approximately 2.1 cm³, constituting a small fraction of the total brain volume, which measures around 425 cm³.^[15] During infancy, rapid brain growth outpaces ventricular expansion; although absolute ventricular volume increases by 280% (to about 8.1 cm³) in the first year, the relative proportion to total brain volume decreases significantly due to accelerated parenchymal development.^[15] By age 2 years, a modest absolute reduction occurs (to roughly 7.4 cm³), further compressing the ventricles relative to the expanding brain tissue and establishing a smaller proportional size compared to the neonatal period.^[15] From childhood through adolescence, continued proliferation of brain parenchyma compresses the ventricular system, resulting in a nonlinear increase in absolute ventricular volume by a factor of approximately 1.5 across this period, though growth rates slow after early childhood.^[16] Sex differences become evident, with males exhibiting slightly larger ventricular volumes, reflecting broader patterns of sexual dimorphism in brain maturation.^[17] These changes maintain the ventricles' role in cerebrospinal fluid circulation while adapting to the overall cranial expansion. In adulthood, the ventricular system stabilizes, with total volume averaging 20-25 mL and occupying about 2% of the intracranial volume (approximately 1,400 mL).^[18] Individual variations in size and shape are substantially influenced by genetics, accounting for up to 75% of variance in older adults.^[19] With aging, beginning around age 60, brain atrophy induces gradual ventriculomegaly, with annual ventricular volume increases of about 1.8%, driven by loss of surrounding neural tissue.^[20] MRI and CT imaging reliably capture these age-related shifts, revealing progressive dilation and altered ventricular relations to adjacent structures without pathological intervention in healthy individuals.^[21]

Physiology

Cerebrospinal fluid dynamics

The cerebrospinal fluid (CSF) is primarily produced by the choroid plexus, a specialized structure composed of modified ependymal epithelial cells located within the ventricles of the brain. These cells actively secrete CSF through a process involving the transport of ions such as sodium (Na⁺) and chloride (Cl⁻) from the blood across the blood-CSF barrier, creating an osmotic gradient that drives water movement. Approximately 80% of CSF production occurs in the choroid plexuses of the lateral, third, and fourth ventricles, with the remaining 20% contributed by ependymal cells lining the ventricular walls and metabolic water from brain tissue. The production rate in adults is approximately 0.3–0.4 mL/min, equivalent to about 500 mL per day, which is roughly three to four times the total CSF volume. The composition of CSF reflects this active secretion, featuring higher concentrations of Na⁺ (135–145 mmol/L) and Cl⁻ (120–130 mmol/L) compared to plasma, along with glucose levels at 40–70 mg/dL (about 60% of blood glucose) to support neuronal metabolism.^[22]^[23]^[24] Once produced, CSF circulates through the ventricular system in a unidirectional path from the lateral ventricles, passing through the interventricular foramina (foramina of Monro) into the third ventricle, then via the cerebral aqueduct to the fourth ventricle. From the fourth ventricle, it exits into the subarachnoid space surrounding the brain and spinal cord through the median aperture (foramen of Magendie) and the lateral apertures (foramina of Luschka). This pathway ensures the even distribution of CSF, with the interconnected ventricular anatomy facilitating continuous flow without significant stagnation under normal conditions. The total circulation time for CSF turnover is about 6–8 hours, allowing for nutrient delivery and waste removal throughout the central nervous system.^[22]^[25] Absorption of CSF primarily occurs outside the ventricular system through arachnoid granulations—protrusions of the arachnoid mater into the dural venous sinuses, particularly the superior sagittal sinus—where it is reabsorbed into the venous bloodstream in a pressure-dependent manner, as well as via dural lymphatic vessels draining to the cervical lymph nodes, with the latter recognized as a major pathway in recent studies. This process is driven by the pressure gradient between the subarachnoid space and the venous system, with normal intracranial pressure (ICP) maintained at 7–15 mmHg in the supine position to balance production and absorption rates. While minor absorption can occur directly from the ventricular walls via perivascular spaces or ependymal routes, it accounts for less than 10% of total CSF clearance, with the bulk handled extracranially. Disruptions in this absorption, such as granulation blockage, can lead to pressure imbalances, though under physiological conditions, it efficiently prevents accumulation.^[22]^[26] The flow of CSF is regulated by a combination of mechanical and physiological factors, including arterial pulsations from the cardiac cycle and respiratory movements that generate pressure waves propagating through the ventricular system. Arterial pulsations impart a pulsatile component to CSF movement, with systolic expansion of cerebral arteries driving forward flow, while respiration modulates bulk flow through changes in intrathoracic and intracranial pressure—expiration typically enhancing caudal-directed flow. The net bulk flow rate through the cerebral aqueduct is approximately 200–300 μL/min in healthy adults, reflecting the steady-state balance with production, though the actual movement includes bidirectional pulsations with a small net forward component. These regulatory mechanisms ensure consistent circulation, adapting to postural changes or activity levels to maintain hydrodynamic stability.^[22]^[27]^[28] Through its dynamics, the ventricular system contributes to CSF homeostasis, maintaining a stable pH of 7.28–7.32 and precise ion balances (e.g., lower potassium at 2.7–3.9 mmol/L and calcium at 1.0–1.2 mmol/L compared to plasma) via active transport in the choroid plexus and diffusion across barriers. The total CSF volume in adults is about 150 mL, with approximately 25 mL (about 17%) residing within the ventricles and the remainder in the subarachnoid spaces, allowing for rapid exchange and buffering of metabolic byproducts. This controlled environment supports neuronal function by regulating osmolarity (around 290–300 mOsm/L) and removing excess ions or proteins, preventing disequilibrium that could affect brain excitability.^[22]^[29]^[30]

Protective functions

The ventricular system, through the cerebrospinal fluid (CSF) it contains, provides mechanical cushioning to the brain by creating buoyancy that reduces the organ's effective weight by approximately 95%, from about 1,500 grams to 25–50 grams, thereby preventing sagging and compression against the skull base.^[22] This buoyant support also absorbs mechanical shocks from trauma, distributing forces across the brain's surface and minimizing direct impact on neural tissues.^[22] The blood-CSF barrier, formed by tight junctions in the choroid plexus epithelium within the ventricles, acts as a selective chemical barrier that tightly regulates the entry of solutes, ions, and molecules from the bloodstream into the CSF, effectively shielding the brain from circulating toxins and pathogens.^[31] This barrier function is distinct from the blood-brain barrier and ensures a controlled chemical environment in the CSF, preventing harmful substances from reaching sensitive neural structures.^[31] CSF within the ventricular system facilitates immune surveillance by enabling the circulation of leukocytes, such as T cells, and antibodies through the subarachnoid spaces and perivascular pathways, allowing these components to patrol and respond to potential threats in the central nervous system.^[32] This dynamic flow supports a baseline neuroimmune response, where immune cells can detect antigens without compromising the brain's isolation.^[33] The compliance of the ventricular system buffers fluctuations in intracranial pressure (ICP), accommodating volume changes from activities like the Valsalva maneuver or postural shifts to maintain stable pressure gradients and prevent acute elevations that could distort brain tissue.^[34] This buffering capacity relies on the deformability of the ventricles and CSF displacement, which absorbs transient pressure increases without significant impact on cerebral perfusion.^[35] Additionally, CSF circulation driven by the ventricular system aids in thermal regulation by dissipating heat from deep brain structures through convective exchange with cooler venous blood and surrounding tissues, helping to stabilize hypothalamic temperature control.^[36] This process ensures even heat distribution and prevents localized overheating during metabolic activity.^[37]

Clinical significance

Hydrocephalus

Hydrocephalus is characterized by the abnormal accumulation of cerebrospinal fluid (CSF) within the brain's ventricular system, resulting in ventricular enlargement due to an imbalance between CSF production and absorption.^[38] This condition arises from disruptions in CSF dynamics, leading to increased intracranial pressure (ICP) that compresses surrounding brain tissue.^[39] It manifests in two primary forms: non-communicating (obstructive) hydrocephalus, where CSF flow is blocked within the ventricular pathways, and communicating hydrocephalus, where CSF flow from the ventricles to the subarachnoid space is unimpeded but absorption at the arachnoid granulations is impaired.^[40]^[41] The causes of hydrocephalus are broadly classified as congenital or acquired. Congenital hydrocephalus, present at birth, often stems from developmental anomalies such as aqueductal stenosis, a narrowing of the cerebral aqueduct that obstructs CSF flow between the third and fourth ventricles.^[41] Acquired hydrocephalus develops later in life due to secondary insults, including brain tumors that block ventricular pathways, infections like bacterial meningitis that cause inflammation and scarring of CSF absorption sites, or intraventricular hemorrhage in premature infants.^[42]^[38] The incidence of congenital hydrocephalus is approximately 1 per 1,000 live births, making it one of the most common central nervous system anomalies in newborns.^[43] Pathophysiologically, hydrocephalus elevates ICP as CSF production outpaces absorption or drainage, causing progressive ventricular dilation and brain compression.^[44] In severe cases, this pressure gradient induces transependymal flow, where CSF leaks through the ependymal lining into periventricular white matter, resulting in interstitial edema and potential neuronal damage.^[39] Acute hydrocephalus presents rapidly with marked ICP spikes, while chronic forms develop gradually, allowing partial compensation but eventual decompensation with sustained tissue strain.^[44] Symptoms vary by age, acuity, and etiology, reflecting the impact of ventricular expansion on adjacent structures. In infants, whose skull sutures are open, manifestations include rapid head enlargement (macrocephaly), a bulging anterior fontanelle, and the "sunset eyes" sign, characterized by downward gaze deviation due to pressure on the midbrain.^[38]^[45] Additional infant signs encompass irritability, poor feeding, and vomiting from brainstem compression. In adults, symptoms often involve chronic headache from ICP elevation, gait disturbances resembling magnetic foot patterns due to frontal lobe and basal ganglia involvement, urinary incontinence, and cognitive decline.^[46]^[47] Acute adult presentations may escalate to nausea, altered consciousness, or papilledema, contrasting with the insidious progression of chronic cases.^[44] Diagnosis relies on clinical evaluation combined with neuroimaging to confirm ventricular dilation. Ultrasonography through the open fontanelle is preferred in infants for initial screening, while computed tomography (CT) or magnetic resonance imaging (MRI) in older children and adults visualizes ventricular enlargement, identifies obstructions, and assesses for underlying causes like tumors.^[48] The Evans' index, calculated as the ratio of the maximum frontal horn width to the maximum internal skull diameter on axial imaging, quantifies ventriculomegaly; values greater than 0.3 indicate pathologic enlargement.^[49] Treatment for hydrocephalus primarily involves surgical intervention to restore CSF balance and alleviate pressure. The most common procedure is the placement of a ventriculoperitoneal (VP) shunt, a flexible tube that diverts excess CSF from the ventricles to the peritoneal cavity for absorption.^[38] An alternative, particularly for obstructive cases, is endoscopic third ventriculostomy (ETV), which creates a new pathway for CSF flow by perforating the floor of the third ventricle, avoiding the need for a shunt in select patients.^[39] Shunt systems may require revisions due to malfunction, infection, or overdrainage, and management often involves multidisciplinary care including monitoring for complications.^[38]

Associated pathologies

Ventriculitis refers to an infection of the cerebrospinal fluid within the ventricular system, often arising as a complication of ventricular shunts or neurosurgical procedures. Common pathogens include bacteria such as Staphylococcus epidermidis, Staphylococcus aureus, and Gram-negative organisms like Klebsiella pneumoniae, as well as fungi in immunocompromised patients.^[50]^[51] Symptoms typically manifest as fever, headache, altered mental status, and signs of meningitis, with potential progression to abscess formation if untreated.^[50] Treatment involves systemic antibiotics combined with intraventricular administration to achieve high local concentrations, particularly for refractory cases, alongside shunt removal and temporary external drainage.^[52]^[53] Tumors within the ventricular system can obstruct cerebrospinal fluid pathways, leading to mass effect and secondary complications. Ependymomas, originating from the ependymal lining, frequently occur in the fourth ventricle and present with symptoms of increased intracranial pressure, including headache, nausea, vomiting, and ataxia due to cerebellar compression.^[54]^[55] Choroid plexus papillomas, benign neoplasms arising from choroid plexus epithelium, are commonly located in the lateral ventricles in children but also affect the fourth ventricle; they cause obstruction or excessive cerebrospinal fluid production, resulting in similar pressure-related symptoms like irritability and lethargy.^[56]^[57] Surgical resection is the primary treatment, with potential adjuvant radiation for malignant variants.^[58]^[59] Atrophy-related ventriculomegaly, also known as hydrocephalus ex vacuo, involves passive enlargement of the ventricles due to surrounding brain tissue loss, without elevated intracranial pressure. This condition is observed in neurodegenerative diseases such as Alzheimer's disease, where parenchymal atrophy leads to compensatory ventricular dilation, distinguishable from active hydrocephalus by normal intracranial pressure and absence of periventricular edema on imaging.^[60]^[61] Similarly, in traumatic brain injury, post-injury atrophy from neuronal death and gliosis results in ex vacuo changes, often accompanied by cognitive deficits but without the dynamic cerebrospinal fluid flow abnormalities seen in obstructive processes.^[62]^[63] Management focuses on treating the underlying atrophy rather than intervening in the ventricular system directly. Congenital malformations of the ventricular system disrupt normal anatomy and cerebrospinal fluid dynamics. Dandy-Walker malformation features a cystic dilation of the fourth ventricle, hypoplasia of the cerebellar vermis, and enlarged posterior fossa, with an incidence of approximately 1 in 10,000 to 30,000 live births; it is associated with genetic mutations in genes like FOXC1 and ZIC1, though most cases are sporadic.^[64]^[65] Symptoms include developmental delays, ataxia, and seizures, often requiring surgical intervention for associated cerebellar anomalies. Chiari malformation type I involves cerebellar tonsillar herniation through the foramen magnum, impeding cerebrospinal fluid flow from the fourth ventricle and potentially causing syringomyelia; its prevalence is estimated at 0.5% to 1% in the general population, with familial patterns linked to genes such as HOXC and connective tissue disorders.^[66]^[67] Clinical features encompass headache exacerbated by Valsalva maneuvers, neck pain, and sensory disturbances.^[68] Iatrogenic complications from ventricular shunting, such as slit ventricle syndrome, arise in patients treated for hydrocephalus, occurring in 4% to 37% of cases due to chronic overdrainage. This results in collapsed, slit-like ventricles, leading to intermittent headaches, vomiting, and altered consciousness from shunt malfunction or intracranial pressure fluctuations.^[69]^[70] Diagnosis relies on imaging showing small ventricles and clinical correlation, with treatment options including shunt revision, programmable valves, or endoscopic third ventriculostomy to restore balanced cerebrospinal fluid dynamics.^[71]^[72]

References

[1]
Neuroanatomy, Ventricular System - StatPearls - NCBI Bookshelf - NIH
The ventricular system of the brain is an interconnected series of cavities filled with cerebrospinal fluid (CSF) that cushions the brain.Introduction · Structure and Function · Embryology · Clinical Significance
[2]
The Ventricular System - Neuroscience - NCBI Bookshelf - NIH
The ventricles are filled with cerebrospinal fluid, and the lateral, third, and fourth ventricles are the site of the choroid plexus, which produces this fluid.
[3]
Ventricular system | Radiology Reference Article - Radiopaedia.org
Jul 23, 2025 · The ventricular system in the brain is a series of interconnecting spaces and channels within the brain composed of cerebrospinal fluid (CSF).Brain ventricle anatomy... · Third ventricle · Lateral ventricle · Question 680
[4]
The Lateral Ventricles: A Detailed Review of Anatomy, Development ...
The lateral ventricles are paired C-shaped structures with a body, atrium, and three projections into the frontal, temporal, and occipital lobes.
[5]
Morphometric Study of the Third Ventricle and Thalamus by...
The mean anteroposterior diameter and transverse diameter of the third ventricle in the age group of 61 years and above are 25.31 ± 4.14 mm and 8.16 ± 1.96 mm, ...Missing: length | Show results with:length
[6]
Anatomic Variability of the Morphometric Parameters of the Third ...
Conclusion The morphometric parameters of the third ventricle of the brain, such as height, anteroposterior diameter, and transverse diameter, depend on the ...
[7]
Fourth ventricle | Radiology Reference Article | Radiopaedia.org
Aug 12, 2025 · The fourth ventricle is part of the brain's ventricular system, filled with CSF, located dorsal to the pons, and is tent-shaped. It extends ...
[8]
5 Cerebral Aqueduct and Fourth Ventricle Anatomy | Neupsy Key
Jun 1, 2020 · 0.21 cm (0.12–0.3 cm). Length of fourth ventricle. 3.17 cm (2.8–3.8 cm). Maximum height of fourth ventricle. 1.24 cm (0.92–1.45 cm). Source: ...
[9]
Neuroanatomy, Fourth Ventricle - StatPearls - NCBI Bookshelf - NIH
The fourth ventricle is the most inferiorly located ventricle, draining directly into the central canal of the spinal cord.
[10]
Chapter 43: THE BRAIN, CRANIAL NERVES, AND MENINGES
The third ventricle presents several recesses (fig. 43-9): optic, infundibular, pineal, and suprapineal. The choroid plexuses of the third ventricle ...Missing: dimensions | Show results with:dimensions
[11]
Neuroanatomy, Cerebral Aqueduct (Sylvian) - StatPearls - NCBI - NIH
The cerebral aqueduct is a narrow 15 mm conduit that allows for cerebrospinal fluid (CSF) to flow between the third ventricle and the fourth ventricle.Introduction · Structure and Function · Embryology · Surgical Considerations
[12]
Totally Tubular: The Mystery behind Function and Origin of the Brain ...
The embryonic brain ventricular space directly reflects the position and shape of the surrounding neuroepithelium, and thus, development of the brain ventricles ...
[13]
Development of the Central Nervous System - Spinal Cord
Prosencephalon · Diencephalon, Thalamus, hypothalamus, and epithalamus, Third Ventricle ; Mesencephalon, Mesencephalon, Midbrain, Cerebral aqueduct.Neurulation · Later Development · Brain And Cerebellum
[14]
Ventricular system and choroid plexuses of the human brain during ...
At stage 14 the future cerebral hemispheres and lateral ventricles begin, and the rhomboid fossa becomes apparent. The medial and lateral ventricular eminences ...
[15]
A Structural MRI Study of Human Brain Development from Birth to 2 ...
Lateral ventricle volume increased 280% in the first year, with a small decrease in the second. The caudate increased 19% and the hippocampus 13% from age 1 to ...
[16]
Ventricular volume change in childhood - PubMed
The ventricular volume in normal children increases with age by a factor of 1.5; the increase is in a nonlinear segmental pattern.
[17]
Sex-related differences and associated transcriptional signatures in ...
May 25, 2025 · Our study has confirmed that males have larger lateral ventricles with faster growth rates, especially for the right lateral ventricle. The ...
[18]
Ventricular system | Radiology Reference Article - Radiopaedia.org
Jul 23, 2025 · From the cephalic to the caudal end, three dilatations are formed: the prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon ...Brain ventricle anatomy... · Third ventricle · Lateral ventricle · Question 680
[19]
Heritability of brain ventricle volume: Converging evidence from ...
Genetic influences accounted for 32-35% of the variance in lateral ventricular volume in childhood, but about 75% of the variance in late middle and older age.
[20]
Brain Volume Changes in Aging Individuals With Normal Cognition
Jun 28, 2023 · There was an overall annual increase in ventricle volume of 1.8%, with a range of 1.0% per year among individuals in their 40s to 2.5% per year ...
[21]
Increased hippocampal shape asymmetry and volumetric ventricular ...
As age increased, asymmetry within the ventricles increased, for both ASD patients and controls.
[22]
Ventricular and Periventricular Anomalies in the Aging and ...
Ventriculomegaly (expansion of the brain's fluid-filled ventricles), a condition commonly found in the aging brain, results in areas of gliosis where the ...
[23]
Physiology, Cerebral Spinal Fluid - StatPearls - NCBI Bookshelf
Aug 9, 2025 · Around 80% of CSF production occurs via a network of modified ependymal cells known as the choroid plexus. This structure consists of a highly ...
[24]
The Choroid Plexus and Cerebrospinal Fluid: Emerging Roles in ...
In humans, the ChP produces 400–600 ml of CSF each day, which is enough to turn over the CSF 3–4 times. The CSF then flows from the lateral ventricles to the ...
[25]
Blood—Cerebrospinal Fluid Barrier - Basic Neurochemistry - NCBI
Instead, CSF production by the choroid plexus is driven by active ion transport that results in a net secretion of Na+ and Cl−, the main ionic constituents of ...Blood--Cerebrospinal Fluid... · The Choroid Plexus... · The Choroid Plexus Is The...
[26]
Cerebrospinal fluid circulation: What do we know and how do we ...
Apr 18, 2018 · After production, CSF movement generally occurs through the ventricular system, assisted, in part, by ciliated ependyma which beat in synchrony.
[27]
Cerebrospinal fluid outflow: a review of the historical and ...
Cerebrospinal fluid (CSF) is produced by the choroid plexuses within the ventricles of the brain and circulates through the subarachnoid space of the skull ...<|control11|><|separator|>
[28]
Respiratory influence on cerebrospinal fluid flow – a computational ...
Jul 5, 2019 · In this study, we explored the importance of respiratory versus cardiac pressure gradients for CSF flow within one of the main conduits of the brain, the ...
[29]
Quantification of cerebrospinal fluid flow through the cerebral ...
Mean net CSF flow through the aqueduct (directed towards the spine) was (mean±std) 332±128 ml/day for venc=5cm/s and 441±149 ml/day for venc=13cm/s, which is in ...
[30]
Cerebrospinal Fluid–Basic Concepts Review - PMC - PubMed Central
The main component of cerebrospinal fluid is water (99%), with the remaining part (1%) made up of protein, glucose, ions, vitamins, and neurotransmitters. The ...
[31]
A computational model of cerebrospinal fluid production and ...
The choroid plexus actively creates an ionic concentration gradient between the blood and the ventricles, which drives water transport. The cerebrospinal fluid ...
[32]
Development of the choroid plexus and blood-CSF barrier - PubMed
Mar 3, 2015 · ... protective effort for the brain: a physical barrier to impede entrance of toxic metabolites to the brain; a "biochemical" barrier that ...
[33]
Immune surveillance in the central nervous system - PMC
Jul 26, 2012 · ... (CSF) barrier, the immune response in the brain can be impressive if ... Leukocytes patrol the healthy brain and spinal cord. Although ...
[34]
T-Lymphocytes Traffic into the Brain across the Blood-CSF Barrier
Mar 4, 2016 · Within the CSF space, T cells inspect the CNS environment for cognate antigens. This gate of entry into the CNS could also prevail at the ...<|control11|><|separator|>
[35]
Management of Cerebral Edema, Brain Compression, and ...
CSF, being lower in pressure than venous or arterial blood, functions as the primary buffer responsible for intracranial compliance; CSF can be displaced from ...
[36]
Intracranial Compliance Concepts and Assessment: A Scoping ...
Oct 24, 2021 · It has been reported that ICC is related to maintaining ICP stability despite changes in intracranial volume. However, this has not been ...
[37]
Thermal Regulation of the Brain—An Anatomical and Physiological ...
Jan 21, 2016 · The robust and relatively constant blood flow in the scalp provides a vascular thermal shielding mechanism to help maintain brain temperature ...
[38]
Brain temperature and its fundamental properties: a review for ...
The venous vasculature, like the arterial vasculature, likely provides a highly effective CSF-venous thermal exchange interface and regulation checkpoint.
[39]
Hydrocephalus | National Institute of Neurological Disorders and ...
Apr 7, 2025 · Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) deep within the brain. This excess fluid causes the ventricles (cavities) within the brain to ...
[40]
Hydrocephalus - StatPearls - NCBI Bookshelf - NIH
In adults, there are four different types; obstructive, communicating, hypersecretory, and normal pressure hydrocephalus (NPH). Congenital or developmental ...Introduction · Etiology · History and Physical · Treatment / Management
[41]
Communicating hydrocephalus | Radiology Reference Article
Dec 17, 2024 · Communicating hydrocephalus is a type of hydrocephalus where CSF is able to leave the ventricular system.
[42]
Hydrocephalus | Johns Hopkins Medicine
Congenital hydrocephalus is present at birth and may be caused by either events or influences that occur during fetal development, or genetic abnormalities.
[43]
Common Cause of Acquired Hydrocephalus
Acquired hydrocephalus develops after birth as a result of neurological conditions such as head trauma, brain tumor, cyst, brain bleed, or infection.
[44]
Hydrocephalus - Case Based Pediatrics Chapter
Non-communicating hydrocephalus, also referred to as obstructive hydrocephalus, involves a disruption in flow of CSF from the ventricles to the subarachnoid ...<|separator|>
[45]
Hydrocephalus: Practice Essentials, Background, Pathophysiology
ICP rises if production of CSF exceeds absorption. This occurs if CSF is overproduced, resistance to CSF flow is increased, CSF resorption is decreased, or ...
[46]
Sunset eye sign | Radiology Reference Article - Radiopaedia.org
Apr 18, 2019 · The sunset eye sign (also known as the setting sun phenomenon) is a clinical phenomenon encountered in infants and young children with raised intracranial ...
[47]
Hydrocephalus - Symptoms and causes - Mayo Clinic
Sep 15, 2023 · Risk factors Much of the time, the cause of hydrocephalus is not known. However, developmental or medical problems can contribute to or trigger ...
[48]
Gait disorder is the cardinal sign of normal pressure hydrocephalus
The cardinal sign of NPH is a hypokinetic gait disorder in which the older adult's feet look as though they are glued to the floor.
[49]
Hydrocephalus | Diagnostic Imaging of Infants and Children
Acute obstructive hydrocephalus causes elevation of intraventricular pressure, ventricular enlargement, and brain expansion. Compression of cortical veins by ...
[50]
Evans index | Radiology Reference Article | Radiopaedia.org
Mar 14, 2025 · Evans index is the ratio of the maximum width of the frontal horns of the lateral ventricles and the maximal internal diameter of the skull at the same level.Evans index · Cella media index · Ventriculomegaly
[51]
Ventriculitis - StatPearls - NCBI Bookshelf - NIH
Oct 6, 2024 · Intraventricular antibiotics are an option if ventriculitis is refractory to systemic therapy.
[52]
Ventriculitis due to multidrug-resistant gram-negative bacilli ...
Apr 26, 2024 · This study aims to analyze the characteristics, ventriculitis evolution, treatment, and outcomes of patients with ventriculitis due to MDR Gram- ...
[53]
Ventriculitis: Infection or Inflammation - PMC - PubMed Central - NIH
Oct 14, 2021 · Higher CSF levels of antibiotics can be achieved with intraventricular injection compared to intravenous dosing. Some antibiotics, such as ...
[54]
Intraventricular Plus Systemic Antibiotic Therapy for Treating ...
We report a rare case of ventriculitis caused by polymyxin-resistant KPC-producing Klebsiella pneumoniae. We eventually eradicated infectious microorganisms ...
[55]
Childhood Ependymoma Treatment (PDQ®) - NCBI - NIH
Jan 6, 2025 · Supratentorial ependymomas: Supratentorial ependymomas may result in headaches, seizures, or location-dependent focal neurological deficits.
[56]
Intracranial ependymomas: The role of advanced neuroimaging in ...
Feb 1, 2021 · Particularly, neoplasms located in the fourth ventricle tend to present with symptoms related to intracranial hypertension, such as progressive ...
[57]
Choroid Plexus Papilloma - StatPearls - NCBI Bookshelf - NIH
Most patients with choroid plexus papillomas present with signs and symptoms of increased intracranial pressure secondary to hydrocephalus.[18] These symptoms ...
[58]
Choroid Plexus Tumor: Diagnosis and Treatment - NCI
Aug 20, 2024 · Symptoms related to choroid plexus tumors depend on the tumor's location. People with choroid plexus tumors may have hydrocephalus—increased ...Missing: obstruction | Show results with:obstruction
[59]
Ependymoma: Diagnosis and Treatment - National Cancer Institute
Aug 20, 2024 · Ependymomas can form anywhere in the CNS. They often occur near the ventricles in the brain and the central canal of the spinal cord. On rare ...Missing: obstruction | Show results with:obstruction
[60]
Choroid plexus papillomas: advances in molecular biology and ...
The most common symptoms are related to increased intracranial pressure and include headache, visual disturbances, nausea, vomiting, and generalized malaise.
[61]
Differences in Brain Morphology between Hydrocephalus Ex Vacuo ...
This study aims to investigate radiological parameters as clinically useful tools to discriminate iNPH from hydrocephalus ex vacuo caused by Alzheimer's ...Missing: trauma | Show results with:trauma
[62]
Multiplicity of cerebrospinal fluid functions: New challenges in health ...
Produced mainly by choroid plexuses, CSF is formed at 0.4 ml/min/g in several mammals. Human production rates vary from 0.3 to 0.6 ml/min depending upon ...
[63]
Therapeutic strategies to target acute and long-term sequelae of ...
Evidence of brain atrophy and ex-vacuo ventriculomegaly (enlarged ventricular space) has been reported following accidental or abusive TBI. Subarachnoid ...
[64]
Facilitated Assessment of Tissue Loss Following Traumatic Brain ...
Mar 14, 2012 · The lost brain tissue is replaced with a fluid filled cavity, hydrocephalus ex vacuo, but TBI may also lead to increased ventricular volume ...Brain Injury Model · Image Analysis · Results
[65]
Dandy-Walker Malformation - StatPearls - NCBI Bookshelf - NIH
Nov 12, 2023 · DWM and related variants have a prevalence of 1 in 350,000 live births in the United States. These malformations account for approximately 1% to ...
[66]
Dandy-Walker malformation - Genetics - MedlinePlus
Oct 1, 2015 · Frequency. Dandy-Walker malformation is estimated to affect 1 in 10,000 to 30,000 newborns.
[67]
Cerebrospinal fluid hydrodynamics in Chiari I malformation and ...
Hindbrain herniation into the foramen magnum reduces the area for CSF flow across the foramen magnum. Severe reduction of CSF flow area (A) within and around ...
[68]
Chiari Malformation Type 1 - StatPearls - NCBI Bookshelf
Chiari 1 malformation can have a genetic basis or be secondary to different conditions involving alterations in the basal skull, including craniosynostosis, ...
[69]
The Pathogenesis of Chiari Malformation and Syringomyelia
Oct 19, 2023 · In Chiari malformation, obstruction of the CSF flow due to a small posterior fossa and hindbrain herniation causes a state of reduced spinal ...
[70]
Slit ventricle syndrome: Historical considerations, diagnosis ...
Aug 27, 2021 · When the distal tip of the central catheter is occluded, the CSF compartment that refers to the ventricular system becomes entrapped, and this ...
[71]
Rare Complications of CSF Diversion: Paradoxical Neuroimaging ...
May 30, 2024 · Slit ventricle syndrome (SVS) is a complication in patients with hydrocephalus who have undergone CSF drainage, occurring in 4–37% of patients ...
[72]
a smooth transition strategy for slit ventricle syndrome - PMC - NIH
Jul 15, 2021 · Slit ventricle syndrome (SVS) is a well-known complication of long-standing shunts. Patients develop intermittent severe headache, vomiting with ...Missing: post- | Show results with:post-
[73]
Endoscopy in the treatment of slit ventricle syndrome - PMC
Aug 18, 2017 · It is characterized by the presence of intermittent headaches, slow refilling of the shunt reservoir and small slit-like ventricles on imaging ...