Pineal cysts are benign (non-cancerous) fluid-filled sacs located in the region of the brain that contains the pineal gland. Small pineal cysts (.5 cm or smaller) are common occurrences, often found incidentally on routine neurological exams. Small pineal cysts rarely cause symptoms (asymptomatic). Larger pineal cysts are rare findings that may cause a variety of symptoms (symptomatic). Symptoms may include headaches, increased pressure on the brain because of accumulation of excessive cerebrospinal fluid (hydrocephalus), and vision abnormalities. Large symptomatic pineal cysts may potentially cause serious conditions such as seizures and loss of consciousness. The exact cause of symptomatic pineal cysts is unknown.
The most common finding associated with symptomatic pineal cysts is headaches. Headaches may occur in three forms: chronic, intermittent headaches; short-term, recurring, sudden (paroxysmal) headaches; or painful, persistent headaches. In most cases, symptoms occur secondary to hydrocephalus or compression of certain structures in the brain near the pineal region.
Hydrocephalus is a condition marked by increased pressure on the brain because of the accumulation of excessive cerebrospinal fluid in the skull. Symptoms secondary to hydrocephalus include headaches, nausea, vomiting, lethargy, seizures, and accumulation of excessive amounts of watery fluid in the optic disks (papilledema).
Affected individuals may also have a variety of symptoms secondary to compression of other structures near the pineal region of the brain. Such symptoms may include double vision (diplopia), blurred vision, dizziness (vertigo), inability to coordinate voluntary movements (ataxia), and paralysis (palsy) of upward gaze (Parinaud’s syndrome).
In rare cases, additional symptoms may occur including loss of consciousness (syncope), mental status changes, and bleeding (hemorrhaging) into the cyst (pineal apoplexy). According to the medical literature, pineal apoplexy has resulted in four deaths in individuals with symptomatic pineal cysts.
In some cases in young children, pineal cysts have been associated with premature sexual development (precocious puberty).
The exact cause of large pineal cysts is unknown. One theory suggests that hormonal influences during pregnancy or menstruation may play a role in the development of large pineal cysts in young women.
Another theory suggests that bleeding (hemorrhaging) in the pineal region may play a role in the development and progression of pineal cysts. Hemorrhaging into an existing asymptomatic pineal cyst may cause it to grow and become symptomatic (hemorrhagic expansion). In one report in the medical literature, a symptomatic pineal cyst developed secondary to hemorrhaging in the pineal region.
Symptoms of large pineal cysts occur because of the compression of surrounding structures by a cyst. Hydrocephalus occurs because of the compression of the aqueduct of sylvius, a structure that normally allows for the passage of excess cerebrospinal fluid.
Compression of the quadrigeminal plate results in Parinaud’s syndrome.
In some cases, in the walls lining a pineal cyst, choroids plexus cells have been detected. These cells are believed to be involved in a process (ionic fluxes) that ultimately attracts water through semipermeable membranes causing enlargement of pineal cysts.
Of the cases reported in the medical literature, symptomatic pineal cysts have affected females more often than males. Theoretically, individuals of any age group can be affected; however, only children and young or middle-aged adults have been reported. Approximately 100 cases of large symptomatic pineal cysts have been reported in the medical literature. However, many cases may go unrecognized leading to under-diagnosis and making it difficult to determine the true frequency of symptomatic pineal cysts in the general population.
A diagnosis of symptomatic pineal cysts may be suspected based upon a thorough clinical evaluation, a detailed patient history, identification of characteristic symptoms and the findings on certain tests specifically computed tomography (CT scan) and magnetic resonance imaging (MRI). During CT scanning, a computer and x-rays are used to create a film showing cross-sectional images of the brain's tissue structure. During MRI, a magnetic field and radio waves are used to create cross-sectional images of the brain.
Symptomatic pineal cysts must be differentiated from pineal tumors. Some pineal tumors may be cystic in appearance and may be indistinguishable from pineal cysts without microscopic examination of affected tissue.
No treatment is prescribed in large pineal cysts that do not cause symptoms (asymptomatic). However, surgical removal (resection) of a cyst may be performed if persistent neurological symptoms are present or if a cyst grows. Asymptomatic cysts should be routinely monitored to detect an increase in size.
Surgical removal (resection) of symptomatic pineal cysts has led to improvement or disappearance of symptoms in most cases. Surgical techniques for removing symptomatic pineal cysts include craniotomy, endoscopy and stereotactic aspiration.
Craniotomy is a procedure during which a section of the skull is opened allowing the surgeon to remove the symptomatic pineal cyst. During this procedure, a small opening may be made into the cyst wall allowing cystic fluid to drain into the normal CSF pathway (fenestration).
Endoscopy is a procedure during which a thin, flexible tubelike instrument is surgically inserted into the skull and used to remove the cyst.
Another procedure called stereotactic aspiration has been used to treat individuals with symptomatic large pineal cysts. During this procedure, a computer creates a three dimensional model of the brain from CT and MRI scans. This model enables the surgeon to accurately locate the cyst within the skull. A tube is surgically inserted into the symptomatic pineal cyst and its fluid contents are drained or sucked (aspirated) out. Stereotactic aspiration is appealing because it is a minimally invasive procedure; however, the cyst may reaccumulate requiring another surgery.
Other treatment is symptomatic and supportive.
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