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Background Despite their unfavorable locations, lesions of the third ventricle can be successfully removed via an interhemispheric, transcallosal approach. In cases with normal ventricular anatomy, this approach requires unilateral or bilateral identification of the foramen of Monro. Technique However, in the presence of abnormal ventricular configuration such as cavum septum pellucidum (CSP), this basic knwoledge needs to be modified. After routine callosotomy, there may be a confusion while entering the CSP due to the invisualization of ventricular landmarks such as the foramen of Monro, thalamostriate vein, and choroid plexus. The floor of the CSP is formed by the fornices, and a direct approach to the interforniceal area is easier via the CSP. But the interforniceal approach is not a routine way to reach the third ventricle, which has higher risks than other modalities. Conclusion This approach should be planned and used in selected cases of the CSP. Opening of the walls of CSP is recommended both to expose both the foramen of Monro and to gain safe access to the third ventricle before manipulating the interforniceal area.

Background Intraventricular tumors are quite rare and become symptomatic with hydrocephalus-related signs such as headache, double vision, and seizures. Also, most of the patients show neuropsychological deficits, especially memory problems and lack of attention. Methods We reviewed the charts and computed tomographic/magnetic resonance images of 15 patients with tumors of the lateral and third ventricle, who were also examined by a neuropsychologist pre- and postoperatively. Neuropsychological testing included tests of attention, memory, executive functions, and concentration. Results Between 1995 and 2003, 7 patients with colloid cysts of the third ventricle (3 men, 4 women; mean age, 38 years), 5 patients with meningiomas of the lateral ventricle (2 men, 3 women; mean age, 51 years), and 3 patients with astrocytomas and ependymoma (2 men, 1 woman; mean age, 38 years) were treated. All patients with colloid cysts and meningiomas showed mental changes, especially attention and memory deficits. Symptoms improved markedly after surgical intervention. The 3 patients with astrocytoma and ependymoma showed normal results pre- and postoperatively. Conclusion Neuropsychological testing is very useful in patients with intraventricular lesions and important for follow-up examinations. It should be included in every workup examination in this small patient group.

Background Colloid cysts are rare tumors (incidence 3.2/1 000 000 pear year) located in the anterosuperior part of the third ventricle. In this article, we present our microneurosurgical experience on 134 patients focusing on the nuances of ITA with demonstrative videoclips. Methods This surgical series is based on the microsurgical experience of the senior author (JH) at 2 Finnish neurosurgical centers (Helsinki and Kuopio, 1980-2007). Surgical anatomy is demonstrated, and the pitfalls of the different surgical steps are analyzed to avoid complications. The series reflects the whole patient profile of Southern and Eastern Finland, without any selection bias. Results There was no surgical mortality, and morbidity remained mainly transitory among 134 patients treated by ITA. Conclusions Favorable overall outcome of this series demonstrates that removal of third ventricular colloid cyst via transcallosal approach is a direct and safe way to treat these lesions.

Background After transendoscopic sonocatheters had been tested in the laboratory for imaging characteristics and practicability, clinical application was studied with special reference to imaging and navigation capabilities, practicability, safety, and preliminary indications. Methods Intraoperative ENS images prepared during surgery on 75 selected patients between 1996 and 2005 were examined. There were 35 female and 40 male patients, and their mean age was 42 years (range, 2-69 years). Within this series, there were 28 cases of ventricular lesions (ventricular hematomas, tumors, and colloid cyst included, 35 cases) with different diagnosis. In most cases, Aloka sono equipment (Aloka Deutschland, Dusseldorf, Germany) was used because equipment supplied by this company had yielded superior imaging results in the laboratory. This work with patients differed from the laboratory work in that 2 sizes (diameters) of catheters were used: 6-F catheters for block-shaft endoscopes and 8-F for hollow-shaft endoscopes. Results Imaging: In clinical use, the sonocatheter has superior imaging and navigation abilities to those seen in anatomical laboratory work. Real-time and online characteristics represent changes such as shifting, pulsation, CSF flow, blood flow, and changes in size and form of structures. When confronted with clinical problems, this technique still has some limitations such as short penetration depth of 3-cm radius and lack of scanning anterior to the endoscope. Navigation: The scan is radial 360° and in an orthogonal plane to the axis of the endoscope. At the tip of the endoscope it delivers an image that looks geometrically like a “brain radar.” Because of its real-time characteristic, ENS has a navigation capacity that markedly differs from usual neuronavigation, but is intuitively usable. Endoneurosonography was applied in 8 hydrocephali, 3 colloid cysts, 5 intraventricular hematomas, 1 septostomy, 11 ETVs, 2 cystostomies, 4 multiple cysts, and 1 tumor biopsy cases. Three illustrative cases are presented. Conclusion Endoneurosonography is a tool for intraoperative real-time and online high-resolution imaging, and neuronavigation of endoscopes with a working channel at least 2 mm in diameter; it also has application in a wide variety of ventricular lesions. Endoneurosonography is limited by short penetration depth and not scanning ahead to the endoscope anteriorly.

A case is reported in which intraoperative ultrasonic microbubble contrast was used to demonstrate the patency of the foramen of Monro following resection of a colloid cyst.

BACKGROUND Several surgical approaches have proven effective in the management of colloid cysts. Cited disadvantages of the transventricular route are its difficulty in patients with small ventricles, and the risk of postoperative seizures; advantages include the avoidance of interhemispheric retraction and venous injury, and callosal section in the transcallosal route. METHODS We retrospectively evaluated patient outcomes after minimally invasive transventricular microsurgical resection. Twenty patients underwent computed tomography-guided stereotactic resection of a colloid cyst based on trajectory planning through the middle frontal gyrus. The mean patient age was 38 years (range, 14–65 years). The colloid cyst was discovered incidentally in one patient; two patients presented in coma. Fourteen patients (70%) had preoperative hydrocephalus. RESEULTS Total or near-total (only a small remnant of cyst wall left attached to the fornix or thalamostriate vein) cyst removal was achieved in all patients. Mean follow-up after surgery was 4.3 years (range, 0.5–11 years). All patients had an excellent outcome (100%) with return to full function or employment status. Postoperative morbidity occurred in one patient (5%) who sustained a small caudate nucleus hemorrhagic contusion associated with temporary hemiparesis. A single postoperative seizure occurred in one patient 5 months after surgery; no patient developed a persistent seizure disorder. CONCLUSIONS This technique relies on the use of a precisely placed limited craniotomy, a small cortical opening (10–20 mm), a precise trajectory to the foramen of Monro, and standard microsurgical instruments. Stereotactic transventricular microsurgical resection provided safe and effective management of patients with colloid cysts, even in the absence of hydrocephalus.

Background Third ventricular colloid cysts account for 0.5% - 1.5% of all intracranial tumors. A thorough search of the world literature since 1858 revealed 1167 cases, for which a more than one-third (36%) management mortality was estimated. One third of the reported cases had modern diagnostics and surgery with minimal morbidity and nearly no mortality. The primary goal of this study was to assess the incidence and present-day management outcome of these lesions in the strictly defined area of Eastern Finland. Methods In a series of 2000 patients with brain tumors from our catchment area (870,000 inhabitants in eastern Finland) during a 14.5-year period (years 1980-1994), 40 patients (mean age, 45 years; range, 19-75 years, with 21 females) had a third ventricular colloid cyst. Thirty-one patients had transcallosal extirpation of their cysts. One additional tumor was extirpated by the infratentorial supracerebellar route to include simultaneous biopsy of a tectal tumor (lipoma). One elderly male with severe cardiac disease received a ventriculoatrial shunt. Five patients, admitted deeply unconscious, died. In two of these five patients, desperate shunting operations were done, but, in the remaining three moribund patients, no treatment was considered to be of any benefit. Two patients with small tumors are being followed up. Results The far lateral transcallosal transforaminal extirpation of the cyst has served our patients well. There was no surgical mortality. The outcome was excellent in 30 patients and good in 3 patients. Follow-up time ranged from 2 months to 14.5 years (mean, 4.3 years). There were no tumor recurrences. Despite good surgical results, management mortality was as high as 13%, Conclusions The incidence of third ventricular colloid cysts is at least 3.2/1 million/1 year. Even nowadays, up to one fifth of these completely benign and treatable tumors are detected too late, with calamitous consequences.

A case of a symptomatic suprasellar Rathke's cleft cyst in a 35-year-old woman is presented. The cyst wall and contents showed large collections of xanthomatous cells. With the exception of a few pituitary hormone-positive cells, immunohistochemical and ultrastructural features of the lining epithelium in this case of Rathke's cleft cyst were indistinguishable from colloid cysts of the third ventricle with similar secondary changes.

We describe the clinical, radiological, and pathological features of an epithelial lined cyst in the cerebellopontine angle of a 54-year-old man who presented with headaches, ataxia, and multiple cranial nerve dysfunction. The surgically excised lesion showed a cyst lined by ciliated columnar epithelium with copious mucin secretion similar to that seen in colloid cysts of the third ventricle and enterogenous cysts of the spinal canal. In addition the cyst contained brownish material with an exuberant xanthogranulomatous reaction and numerous cholesterol clefts. This lesion closely resembled a cholesterol granuloma by radiographic and pathologic studies. Although two examples of neuroepithelial lined cysts have been described in the cerebellopontine angle, to our knowledge a lesion similar to that in our patient has not been reported previously.

Intraoperative real-time ultrasound was used to assist localization and surgical removal of colloid cysts in patients without ventriculomegaly. In the most commonly used surgical approach for removal of colloid cysts, dilated lateral ventricles can expedite the localization of lesions because, once entered surgically, a dilated ventricle offers more space near the foramen of Monro in which to work. Additionally, the enlargement of the foramen of Monro, seen with hydrocephalus, provides greater accessibility to the colloid cyst. In patients with symptoms related to the colloid cyst. In patients with symptoms related to intermittent obstruction of cerebral fluid flow but with normal-sized ventricles, the precise localization of the foramen of Monro and colloid cyst is more difficult and may result in unnecessary exploration/resection of brain. Using intraoperative ultrasound, the colloid cyst and adjacent anatomic structures can be clearly visualized regardless of ventricular size. Intraoperative ultrasonography has a unique role in the operative treatment of patients with colloid cysts and nondilated ventricles.

Ultrastructural findings of an epithelium-lined cyst in the left pretectal region are reported. A 38-year-old woman developed a sensory disturbance on her right side and blurring of vision. Computed tomography scans and magnetic resonance images disclosed a round cystic lesion in the left pretectum. Light microscopically, the cyst was found to be lined by a single layer of cuboidal epithelial cells. Electron microscope examination revealed that the epithelial cells of the cyst possessed clear nuclei, abundant tonofilaments, and glycogen granules, featured as well as the usual organellae. The free surface of the epithelial cells had numerous finger-like microvilli with coating materials. These cells were interconnected by well-developed desmosomes and interdigitations, and also possessed basal lamina materials on the basal surface. These cytological features suggest a heterogenous origin of the cells rather than a neuroepithelial one.

Two cases of third ventricle tumors with histological features of both colloid cysts and xanthogranuloma are described. One presented with signs of recurrent chemical meningitis. The association between these two lesions is easily explainable by their histogenesis.

Between December 1979 and September 1986, 11 patients with colloid cysts of the third ventricle were operated on by a stereotactic procedure with Talairach's system. Stereoscopic angiography and ventriculographic study allowed for a percutaneous (twist-drill hole diameter: 2.5 mm) stereotactic aspiration of the cysts. The operations were successful, and there were no intraoperative or postoperative mortalities but just mild transient morbidity in three cases. Six cysts were evacuated completely, and five only partially. The mean residual volume was 19% of the initial one. Clinical and anatomical results are presented, and the advantages of this stereotactic procedure are discussed.

Colloid cysts may be found in any part of the third ventricle. The authors report that four out of 12 patients with colloid cysts of the third ventricle suffered acute neurological deterioration, and unilateral ventriculostomy resulted in dramatic recovery in two patients. Unilateral ventriculostomy followed by clinical assessment and computed tomographic scanning is an acceptable approach in emergency situations; computed tomographic scanning allows early detection of third ventricular colloid cysts. Ventriculoperitoneal shunting provides a laternative measure to surgical removal of the cyst. Definitive management soon after diagnosis and before acute neurological deterioration is recommended. The cases presenting with sudden death in the literature are reviewed.

Searching the medical literature for persistent memory loss following section of the anterior fornix in humans, 13 reports were found and reviewed. They comprised 193 patients of whom 180 underwent fornicotomy for the treatment of epilepsy, and 13 underwent removal of third ventricle colloid cysts. Only 4 were reported to have persistent memory loss postoperatively and they were in the colloid cyst group. Within the limitations inherent to this type of analysis and to the problems of detection and quantification of memory deficits, the reviewed material supports the hypothesis that with anterior fornix section we are only interfering with a part of the structural system subserving memory and that the tumor, the surgical trauma, or other destructive pathology, or a combination of factors including the variability of neural localization, may cause persistent memory loss by additional damage to structures other than the anterior fornix. Language and geographical barriers may explain the apparent failure in communication between early investigators.