| disease | Lateral Ventricle Tumor |
There are two lateral ventricles, one on each side, with irregular shapes located within the frontal, parietal, occipital, and temporal lobes. They are divided into five parts: the anterior horn, inferior horn, posterior horn, body, and trigone, containing cerebrospinal fluid secreted by the choroid plexus tissue within the lateral ventricles. Tumors in the lateral ventricles originate from the ventricular walls, choroid plexus tissue, or ectopic tissues. Common types include meningiomas, ependymomas, choroid plexus papillomas, and epidermoid cysts, with meningiomas being the most frequent. According to extensive case statistics, gliomas are more common in the anterior part of the lateral ventricles, while meningiomas often occur in the posterior part. Choroid plexus papillomas typically arise in the trigone and may extend to other parts of the ventricle, sometimes growing through the interventricular foramen into the third ventricle. Overall, tumors in the lateral ventricles are more likely to develop in the anterior part and trigone. They can occur at any age but are more common before the age of 20, with a slightly higher incidence on the left side and in males than in females.
bubble_chart Clinical Manifestations
The ventricles are cavities within the brain that contain cerebrospinal fluid. Therefore, their clinical manifestations depend on the size and location of the tumor. Symptoms and signs only appear when the tumor obstructs the cerebrospinal fluid circulation pathway or compresses surrounding brain tissue, such as increased intracranial pressure and focal symptoms.
1. Increased intracranial pressure: For tumors in the lateral ventricles, when the tumor is very small or does not obstruct cerebrospinal fluid circulation, the patient may have no obvious symptoms at all. When cerebrospinal fluid circulation is impaired (due to obstruction of the interventricular foramen or partial ventricular obstruction), increased intracranial pressure occurs, clinically manifested as headache. Headache is also the initial symptom for most patients. According to statistics, about 92.5% of patients with lateral ventricular tumors report headache as their first symptom. Headache often occurs episodically, intermittently, or with paroxysmal worsening. When the interventricular foramen or part of the ventricle (upper or lower horn) is blocked, obstructive hydrocephalus occurs. Due to the rapid expansion of the ventricles, the patient's headache is often unbearable, and severe cases may experience nausea and vomiting. Some patients may suffer sudden unconsciousness or even death due to a sudden increase in intracranial pressure leading to brain herniation. Tumors in the lateral ventricles have a certain degree of mobility and often act like a valve, suddenly blocking the cerebrospinal fluid circulation pathway, causing acute intracranial pressure elevation, which is also the reason for episodic headaches. When the obstruction is relieved due to changes in body or head position, the patient's headache may quickly stop. If the obstruction recurs, the headache returns, and this cycle may repeat multiple times. As a result, a few patients may repeatedly hit their foreheads on the ground or assume a knee-chest position during each episode.
During severe headaches, patients may experience tonic spasms or even die from brain herniation. Due to long-term increased intracranial pressure, patients may experience vision deterioration, and children may exhibit an enlarged head with a "cracked pot sound" upon percussion.2. Focal symptoms: Focal symptoms, also known as localizing signs, do not appear when the tumor is small and does not compress or invade surrounding brain tissue. As the tumor grows and compresses or damages different areas of surrounding brain structures, various symptoms and signs of brain damage emerge. The tumor may involve the internal capsule or basal ganglia or grow into the brain parenchyma, leading to hemiplegia or monoplegia, sensory disturbances, and milder contralateral central deviation of the mouth, homonymous hemianopia, etc. If the left temporo-parieto-occipital junction is affected, the patient may develop agnosia and aphasia. The severity of clinical symptoms caused by involvement of periventricular tissue often fluctuates with changes in intracranial pressure. Symptoms become more pronounced when intracranial pressure is severely elevated and may temporarily improve when it decreases.
3. Mental disorders: Patients with increased intracranial pressure may exhibit varying degrees of psychiatric symptoms. Generally, symptoms are mild, clinically manifesting as memory decline, general weakness, delayed responses to surroundings, and mental fatigue.
4. Optic disc changes: In the early stages of increased intracranial pressure, patients may exhibit optic disc edema, characterized by blurred disc margins, disappearance of the physiological cup, and sometimes visible radial small blood vessels, patchy tufted vascular clusters, and venous pulsations. In advanced stages, secondary optic atrophy occurs, leading to vision deterioration or even blindness. This is the result of long-term increased intracranial pressure. Patients often experience transient amaurosis—paroxysmal episodes of darkness before vision deteriorates—which is a signal of impending vision decline.
bubble_chart Auxiliary Examination
1. Cerebrospinal Fluid Examination The patient's cerebrospinal fluid pressure is elevated, and the protein content in the cerebrospinal fluid is also increased, with the highest levels found in the ventricular fluid. The protein content in the lumbar puncture sample is relatively lower. The protein content in the cerebrospinal fluid on the side of the tumor is higher than that in the contralateral lateral ventricle. The cell count in the cerebrospinal fluid is slightly elevated, and tumor cells may sometimes be detected.
2. Skull X-ray Plain Film Skull X-ray is a simple diagnostic method for lateral ventricular tumors, with radiographic signs manifesting in two aspects: ① Signs of increased intracranial pressure: increased digital impressions on the inner table of the skull; changes in the bone structure of the sella turcica, including absorption or even disappearance of the posterior clinoid process, shortening of the dorsum sellae, and in severe cases, complete disappearance of the dorsum sellae; prolonged intracranial hypertension may lead to bone absorption, atrophy, and thinning of the skull. ② Tumor calcification: also referred to as intracranial pathological calcification. Calcification in lateral ventricular tumors is not uncommon, often seen in ependymomas and choroid plexus papillomas. The calcification in ependymomas typically appears as scattered punctate aggregations forming multiple spherical calcifications within the lateral ventricle. Choroid plexus papillomas frequently occur in the trigone of the lateral ventricle, with calcification characterized by unilateral calcification in the trigone region or bilateral calcification that exceeds the normal calcification pattern of the choroid plexus. The calcification in meningiomas often presents as punctate, flaky, needle-like, or radial patterns.
4. Ventriculography Ventriculography is a highly significant diagnostic method for lateral ventricular tumors, directly revealing the size and location of the tumor and enabling both localization and qualitative diagnosis. Since lateral ventricular tumors are prone to obstructing the foramen of Monro, ventriculography may show ventricular enlargement, particularly on the tumor side, along with filling defects and tumor shadows within the ventricle. For larger tumors in the trigone of the lateral ventricle, pneumoencephalography may reveal a gas-encapsulated mass, and sometimes contralateral displacement of the lateral ventricle.
5. Other Examinations Electroencephalography may show focal slow waves. Ultrasonography may reveal midline shift. Brain CT scans provide crucial diagnostic evidence for lateral ventricular tumors, displaying the tumor's size, shape, and location, and sometimes enabling qualitative diagnosis.
Lateral ventricle tumors can be easily diagnosed based on their distinctive clinical manifestations and the results of auxiliary examinations, but they are prone to be confused with the following diseases and require differentiation.
(1) Third ventricle tumors: Third ventricle tumors often present with headache as the initial symptom. The headache is paroxysmal, caused by the sudden obstruction of the cerebrospinal fluid circulation pathway, and can occur abruptly. When the obstruction is relieved, the headache may alleviate or disappear. It is closely related to changes in head position, generally easing when prone and worsening when supine. Third ventricle tumors are often accompanied by symptoms of hypothalamic damage, such as diabetes insipidus, obesity, and drowsiness. Ventriculography showing a filling defect in the third ventricle can confirm the diagnosis.
(2) Fourth ventricle tumors: Fourth ventricle tumors typically present with significant intracranial hypertension but few localizing signs. The clinical manifestations are often a combination of headache, dizziness, and vomiting, caused by increased intracranial pressure. Local damage symptoms may also be observed. The floor of the fourth ventricle is adjacent to multiple cranial nerve nuclei, and when the tumor compresses or invades these nuclei, symptoms of cranial nerve damage may appear, including tinnitus, hearing loss, dysphagia, hoarseness, impaired tongue movement, and extraocular muscle paralysis. Occipital bone foramen magnum herniation is also relatively common, clinically presenting as a forced posture. Additionally, patients may exhibit cerebellar damage symptoms, such as unsteady gait and a tendency to fall. Patients may also show optic disc edema and ocular tremor. Ventriculography revealing a filling defect in the fourth ventricle and tumor tissue shadows can confirm the diagnosis.
(3) Craniopharyngioma: Craniopharyngioma is a tumor of embryonic remnant tissue, originating from residual epithelial cells of the craniopharyngeal duct. It mostly occurs in children and primarily grows in the suprasellar or intrasellar regions, rarely in the sphenoid sinus. Whether suprasellar or intrasellar, the tumor can grow upward, with some cases extending into the third ventricle or even the lateral ventricle. In children, increased intracranial pressure is often the initial symptom, clinically presenting as headache, nausea, and vomiting, along with neck stiffness, neck pain, and diplopia. In adults, upward tumor growth compressing the visual pathway often leads to changes in vision and visual fields. Both children and adults may exhibit endocrine dysfunction, clinically presenting as hypogonadism, delayed growth, and disturbances in water and fat metabolism. Visual field defects, particularly bitemporal hemianopia, are common. Craniopharyngiomas in the third ventricle do not cause vision or visual field changes. Typical skull X-ray findings of craniopharyngioma include signs of increased intracranial pressure, with punctate calcifications in the intrasellar or suprasellar regions that may coalesce, and the sella turcica appearing spherical or basin-shaped.
(4) Hydrocephalus: Hydrocephalus can be divided into congenital hydrocephalus and hydrocephalus caused by acquired diseases.
1. Congenital hydrocephalus: Congenital hydrocephalus results from congenital malformations in infants and young children, with causes including: ① Malformations of the cerebral aqueduct, commonly bifurcation or stenosis, and occasionally a membrane in the aqueduct; ② Arnold-Chiari malformation: herniation of the cerebellar tonsils, medulla oblongata, and fourth ventricle into the occipital bone foramen magnum or spinal canal, obstructing cerebrospinal fluid circulation; ③ Atresia of the median and lateral apertures of the fourth ventricle. Congenital hydrocephalus caused by atresia of the cerebral aqueduct or the median and lateral apertures of the fourth ventricle is also known as obstructive hydrocephalus.
2. Hydrocephalus caused by acquired diseases: Acquired non-tumorous causes of hydrocephalus include infections of the meninges, subarachnoid hemorrhage, and cerebral cysticercosis.
In infants with hydrocephalus, the head continuously enlarges and droops, with a prominent forehead, downward gaze, exposed sclera, separated cranial sutures, and a large, bulging anterior fontanelle that produces a "cracked pot sound" when percussed. The child may also experience nausea and vomiting, intellectual disability, and reduced vision or even blindness. Some children may have associated spinal meningocele or spina bifida. In adults, symptoms only manifest as increased intracranial pressure, such as headache, nausea and vomiting, and optic disc edema, without head enlargement; ventriculography or pneumoencephalography reveals dilation of the ventricular system.
(5) Cerebral cysticercosis This refers to cysticercosis in the ventricular system, mostly occurring as a single lesion with a relatively large size, floating freely within the ventricle, though some may adhere to the ventricular wall. If it obstructs the cerebral aqueduct, the median aperture of the fourth ventricle, or causes inflammatory adhesions in these structures, obstructive hydrocephalus may develop. Cysticerci located in the basal cisterns are prone to rupture, forming grape-like clusters that accumulate in the cisterns and lead to thickening and adhesions of the arachnoid membrane, which can also result in hydrocephalus. Clinically, patients may experience headache, vomiting, and symptoms of increased intracranial pressure. Some patients with seasonal disease may lose consciousness. In some cases, rupture of the cysticerci and stimulation of the brain by the cystic fluid can cause meningeal irritation. Cerebral cysticercosis can also be multiple, existing not only in the ventricles but also in the brain tissue, leading to corresponding focal symptoms due to brain tissue damage. Approximately 80% of patients experience epileptic seizures. Patients with seasonal disease often have subcutaneous nodules, which can be confirmed by excision biopsy. Stool examination often reveals adult proglottids and eggs. Cerebrospinal fluid protein levels are elevated, and complement fixation tests are positive. Ventriculography shows uniform dilation of the ventricular system above the obstruction and may reveal cysticercus shadows.
(6) Septum pellucidum tumors The septum pellucidum is a thin membrane between the left and right lateral ventricles. Tumors arising here are commonly oligodendrogliomas, followed by ependymomas, glioblastomas, and astrocytomas. About 80% of cases occur in adults aged 20–40. Some patients may exhibit consciousness disturbances and forced head positioning. If the tumor invades the frontal lobe or corpus callosum, patients may develop psychiatric symptoms, central deviation of the mouth, etc. Due to the tumor's intraventricular location, patients often experience increased intracranial pressure and elevated cerebrospinal fluid protein levels. A few cases may show abnormal calcifications on skull X-rays. Ventriculography and pneumoencephalography reveal filling defects in the lateral ventricles and tumor shadows. Brain CT scans can provide a definitive diagnosis.
(7) Thalamic tumors The clinical manifestations primarily include increased intracranial pressure and local damage symptoms. Increased intracranial pressure results from tumor compression of the cerebral aqueduct, interventricular foramen, or third ventricle. Patients may experience headache, nausea, vomiting, optic disc edema, motor and sensory deficits on the contralateral side of the lesion, homonymous hemianopia, unequal pupil size, and sluggish light reflexes. Some patients may exhibit drowsiness, polyuria, and obesity, which can help differentiate them from lateral ventricular tumors.
(8) Midbrain tumors Midbrain tumors, especially those in the midbrain tegmentum, often present early with symptoms of increased intracranial pressure due to compression of the cerebral aqueduct, and this is frequently the initial symptom. Patients may also exhibit oculomotor nerve palsy, hemiplegia, hemichorea or athetosis, and oculomotor nerve palsy combined with contralateral hemiparesis. Ventriculography shows uniform and significant dilation of the lateral and third ventricles, while the fourth ventricle may not be visualized.
