A colloid cyst is a non-malignant

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

in the brain. It consists of a gelatinous material contained within a membrane of epithelial tissue. It is almost always found just posterior to the foramen of Monro in the anterior aspect of the

third ventricle The third ventricle is one of the four connected ventricles of the ventricular system within the mammalian brain. It is a slit-like cavity formed in the diencephalon between the two thalami, in the midline between the right and left lateral v ...

, originating from the roof of the ventricle. Because of its location, it can cause

obstructive hydrocephalus Hydrocephalus is a condition in which an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased pressure inside the skull. Older people may have headaches, double vision, poor balance, urinary inco ...

and

increased intracranial pressure Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury (mmHg) and at rest, is normally 7–15 mmHg for a supine adult. Th ...

. Colloid cysts represent 0.5–1.0% of intracranial tumors. Symptoms can include

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

vertigo Vertigo is a condition where a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. This may be associated with nausea, vomiting, sweating, or difficulties w ...

memory deficit Amnesia is a deficit in memory caused by brain damage or disease,Gazzaniga, M., Ivry, R., & Mangun, G. (2009) Cognitive Neuroscience: The biology of the mind. New York: W.W. Norton & Company. but it can also be caused temporarily by the use o ...

diplopia Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...

, behavioral disturbances, and in extreme cases, sudden death. Intermittency of symptoms is characteristic of this lesion. Untreated pressure caused by these cysts can result in

brain herniation Brain herniation is a potentially deadly side effect of very high pressure within the skull that occurs when a part of the brain is squeezed across structures within the skull. The brain can shift across such structures as the falx cerebri, the te ...

. Colloid cyst symptoms have been associated with four variables: cyst size, cyst imaging characteristics, ventricular size, and patient age. Their developmental origin is unclear, though they may be of endodermal origin, which would explain the mucin-producing, ciliated cell type. These cysts can be surgically resected, and opinion is divided about the advisability of this.

Symptoms

Patients with third-ventricular colloid cysts become symptomatic when the tumor enlarges rapidly, causing

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

(CSF) obstruction, ventriculomegaly, and increased intracranial pressure. Some cysts enlarge more gradually, however, allowing the patient to accommodate the enlarging mass without disruption of CSF flow, and the patient remains asymptomatic. In these cases, if the cyst stops growing, the patient can maintain a steady state between CSF production and absorption and may not require neurosurgical intervention.

Diagnosis

Colloid cysts can be diagnosed by symptoms presented. Additional testing is required and the colloid cyst symptoms can resemble those of other diseases. MRI and CT scans are often used to confirm diagnosis.

Treatment

There are various management options depending on the severity of symptoms and their effects on the patient. The main management options are observation, craniotomy for microsurgical resection, neuroendoscopic removal, stereotactic drainage, and CSF diversion with bilateral ventriculoperitoneal shunting placement.

Surgical resection

Multiple studies have discussed how to remove a colloid cyst. One option is an endoscopic removal. An endoscope is inserted into the brain via a small incision and then moved toward the tumor in the ventricular compartment. The tumor is hit with an electric current. The interior of the cyst is removed followed by the cyst wall. The electric current is then used to kill the remaining pieces of the cyst. This whole process, including closing of the incision and removal of the scope, is completed within 45 minutes to an hour. The patients are able to leave the hospital after 1 or 2 days. Quality of life is found to be better following endoscopic excision than microsurgery, with cysts smaller than 18 mm showing better cognitive outcome. Another study found that

ventriculomegaly Ventriculomegaly is a brain condition that mainly occurs in the fetus when the lateral ventricles become dilated. The most common definition uses a width of the atrium of the lateral ventricle of greater than 10 mm. This occurs in around 1% ...

may not be a contraindication for endoscopic removal, as the condition has comparable complication rates. Another study experimented with a smaller retractor tube, 12 mm instead of 16–22 mm. The surgery was successful in removing the cyst; the smaller retractor tube minimized resection injury. Neuroendoscopic third

ventriculostomy Ventriculostomy is a neurosurgical procedure that involves creating a hole (stoma) within a cerebral ventricle for drainage. It is most commonly performed on those with hydrocephalus. It is done by surgically penetrating the skull, dura mater, an ...

during surgery can be used to prevent further postoperative hydrocephalus. This removes the need for insertion of bilateral shunts. Patients who have had a colloid cyst removed from the third ventricle sometimes experience some difficulty with day‐to‐day memory. Mammillary body atrophy in patients with surgical removal of colloid cysts indicates that this atrophy is partly due to a loss of temporal lobe projections in the fornix.

References

External links

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