Colloid Cysts Treatment & Management

Updated: Apr 17, 2016
  • Author: Lawrence S Chin, MD, FACS, FAANS; Chief Editor: Brian H Kopell, MD  more...
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Treatment

Medical Therapy

Medical treatment of these lesions is not appropriate or indicated if the patient is symptomatic.

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Surgical Therapy

Surgery is often indicated for these lesions and should be performed in a timely manner. The goals are to relieve hydrocephalus and to remove the risk of deterioration in clinical status.

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Preoperative Details

If the patient appears obtunded, urgent ventricular drainage is usually indicated and bilateral ventricular drainage may be frequently required as well. If no neurological deterioration has occurred and the patient is stable, CSF diversion is not indicated because enlarged ventricles can facilitate the surgical approach.

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Intraoperative Details

The 3 approaches most commonly used are the transcortical approach, the interhemispheric transcallosal approach, and the endoscopic approach. Stereotactic drainage/aspiration has been used, but it is a blind technique that may fail because the cyst contents may be too viscous to drain. Furthermore, the recurrence rate is high because the cyst wall is usually retained. Similarly, the endoscopic approach has a higher rate of incomplete cyst resection, which may increase recurrence rates. Microsurgical resection through either the transcortical-transventricular or transcallosal approach is still considered the criterion standard for treatment of symptomatic patients with colloid cysts. [9]

Transcortical approach

The transcortical approach involves making a corticectomy over the middle frontal gyrus and proceeding to the frontal horn of the lateral ventricle. Intraoperative ultrasonography may aid in the approach to the ventricle. The use of tubular retractors in the brain may help create an operative corridor for the surgeon to work through. [1] The foramen of Monro is visualized at the convergence of the septal veins, the thalamostriate vein, and the choroid plexus. The fornix arches over the superior and anterior margins of the foramen. Avoiding the fornix is important because unilateral fornix damage has been associated with amnesia (both anterograde and retrograde).

The cyst should be readily visualized through the foramen. The cyst is then punctured and the contents are aspirated, internally decompressing the walls of the cyst. Avoiding excessive retraction of the walls of the lateral ventricle is important because the genu of the internal capsule is in the subependyma. Other concerns include damaging the thalamostriate veins, which can result in basal ganglia damage. After the cyst has been decompressed, completely removing it to prevent recurrence is essential. Leaving a small portion of the cyst behind may occasionally be necessary if it is attached to either the thalamostriate or internal cerebral veins.

Interhemispheric transcallosal approach

The interhemispheric transcallosal approach avoids incising the cortex. A frontal (usually right) craniotomy is made from about two-thirds anterior to one-third posterior to the coronal suture, crossing the midline to expose the superior sagittal sinus. The right frontal lobe is then retracted laterally, and the corpus callosum is exposed. Draining cortical veins must be avoided if possible. The preoperative MRI can help identify potential veins. A 1-cm incision is made in the corpus callosum, allowing entry to the lateral ventricle. The foramen of Monro can then be visualized, and the septum pellucidum may be divided to look into the contralateral ventricle. Either ventricle may be entered through a standard right frontal transcallosal approach. Close inspection of the orientation of the choroid plexus, the caudate nucleus, and the foramen of Monro helps determine which of the ventricles has been entered.

Endoscopic approach

The endoscopic approach is the same as the transcortical approach, except that the former is accomplished through a burr hole. The cyst is punctured and aspirated through the working channels of the endoscope. Instrumentation is limited by the size of the working channels, as is the ability to perform bimanual tasks. Use of the endoscope also requires the presence of a fluid environment, which reduces visibility, clarity, and effectiveness of the cautery. Development of new technologies such as improved endoscopic cutting devices will continue to bridge the gap in performance with open surgical techniques. [2]

The endoscopic approach has the advantage of reducing operative time and hospital stay. In addition, the infection risk appears to be less than craniotomy. The primary drawback is the higher incidence of incompletely resected cysts leading to potential cyst regrowth and a need for additional procedures. Also, an endoscopic approach may potentially need to be converted into an open procedure because of difficulty in cyst aspiration or excessive bleeding. This possibility should be discussed with the patient and family prior to surgery. [3, 9]

A combination of microsurgery and stereotactic guidance of a rigid endoscope overcomes many of the limitations of conventional open craniotomy and the pure endoscopic approach. [4] The ventriculostomy is performed using stereotactic guidance, thus allowing the surgeon to approach the foramen of Monro with minimum trauma to the brain. A sheath can be placed, allowing sufficient room for placement of an endoscope. This also allows for specially designed instrumentation to be placed for dissection and electrocautery. Cerebrospinal fluid (CSF) can be removed, which improves visualization through the endoscope and also use of the instruments. Removal of the colloid cyst is the same as with conventional microinstruments. Depending on variations of anatomy, variations in technique have also been developed. In patients with a cavum septum pellucidum, the transcavum septum pellucidum interforniceal approach has been described, although the risk of bilateral forniceal injury is serious and must be avoided.

A common concern regarding the endoscopic approach is the possibility of cyst recurrence with remnants left during the original surgery. A study showed that these remnants do lead to a higher rate of cyst recurrence as compared with patients that had complete cyst removal. Furthermore, postoperative MRI was not sensitive to detecting coagulated cyst remnants that were noted in the operative report. The authors conclude that every attempt must be made to completely remove the cyst wall and contents. [25] However, not all cyst recurrences are symptomatic or require repeat observation. In fact, many of these patients can be observed. Also, the relative risk of neurological injury from attempts at complete cyst removal versus that of recurrence is not known.

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Postoperative Details

Each approach has specific risks and complications. The transcortical approach carries an increased incidence of epilepsy. The transcallosal approach decreases the risk of postoperative epilepsy but risks venous infarction and contralateral leg weakness from prolonged retraction. An extensive callosal resection may also cause temporary mutism. One study has indicated that restricting the callosal resection to 1 cm may reduce postoperative cognitive deficits. [5] Excessive manipulation of the fornix may affect memory. The endoscopic approach is the least invasive, but it can be used only on cysts that can be aspirated. Large cysts cannot be removed with this technique. A steeper learning curve exists with the endoscopic technique. The endoscopic approach generally requires a shorter hospital stay, although similar results are seen with small craniotomies, which reduce operative time and hospital stay.

Hydrocephalus can persist after surgery, even after resection of the cyst. This may be secondary to spillage of the cyst contents or bleeding during surgery. Patients with long-standing hydrocephalus may lose compliance in their ventricular system and be left with persistently enlarged ventricles despite normal pressures. If there is a concern during surgery, a ventricular catheter can be placed intraoperatively to safeguard against ventricular dilatation or intraventricular hemorrhage. Patients can usually be weaned off the ventriculostomy, but in some cases a ventriculoperitoneal shunt may be needed.

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Follow-up

Colloid cysts are usually cured after successful aspiration and complete resection. Hydrocephalus may develop despite removal of the cyst, and periodic CT scans should be performed.

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Complications

Potential complications of surgery include seizures, postoperative hematoma, infection, venous infarct, memory deficit, mutism, and hemiplegia. In a series of 80 patients operated on by the transcallosal transforaminal approach, the complications encountered were postoperative seizures in 6, acute hydrocephalus in 4, venous cortical infarct in 4, transient hemiparesis in 4, transient memory impairment (especially for immediate recall) in 9, mutism in 1, subdural hematoma in 1, meningitis in 3, and tension pneumocephalus in 1. There were 2 deaths. [10]

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Outcome and Prognosis

Preoperative function partly determines patient outcome; most patients tolerate resection well.

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Future and Controversies

With an increasing emphasis on noninvasive therapies, the endoscopic approach is becoming more popular. In the opinion of the authors, the open surgical approach provides the safest exposure with controlled resection of the cyst. The illumination and magnification provided by the operating microscope allow more precise coagulation and dissection of critical structures than afforded by endoscopy.

As endoscopic technology continues to improve, the outcomes with endoscopy is now rivaling traditional craniotomy. The importance of complete cyst resection is still under debate. Certainly, leaving cyst remnants leads to a higher rate of recurrence, but the neurological cost to the patient of aggressive attempts at cyst removal needs to be weighed against a higher recurrence rate; not all cyst recurrences require surgery.

Lastly, radiosurgery is not known to be effective for colloid cysts. In most cases, this disease entity still requires a surgical treatment.

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