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Dear Editor, We would like to present a unique case of an iatrogenic metastasis of a colloid cyst in a patient who underwent neuroendoscopic ventricular surgery. A female in her 40s arrived at the emergency room at the Rambam Medical Center complaining of a headache ranging in severity from mild, tolerable to lately moderate to severe, worsening over the last 3 months. Her neurological examination was normal. A computed tomography (CT) scan revealed a hyperdense mass at the foramen of Monro suggesting a colloid cyst of the third ventricle. Her headache was attributed to the propensity of the cyst to increase the intracranial pressure by intermittently blocking the outflow of the cerebrospinal fluid (CSF) from the lateral ventricle to third through the interventricular foramina of Monro. Preoperative magnetic resonance imaging (MRI) and CT confirmed the diagnosis of a colloid cyst in its typical location (Fig. 1a, b and c). The rapid escalation of her symptoms justified an endoscopic operation for removal of the tumor. During the procedure, subsequent to the detachment of the cyst from the roof of the third ventricle while trying to retrieve it with the endoscope’s forceps, loss of control of the cyst occurred; gravitationally it rolled posteriorly; a postoperative CT and MRI scan (Fig. 2a, b, c and d) showed that it had settled in the right occipital horn. A conservative management plan consisting of follow-up imaging and clinic visits was adopted upon her being asymptomatic and resolut ion of the hydrocephalus. Well-known complications of this procedure are diverse; temporary or rarely permanent memory loss and mutism, intraventricular hemorrhage and aseptic meningitis due to spillage of the cyst contents are described widely in the literature [1]. Iatrogenic metastasis of a complete, unruptured and unevacuated colloid cyst is an unfamiliar complication; one case report exists describing the loss of a colloid cyst after its incision and evacuation of its colloid content [2]. In our case, compared to the original position, the cyst’s new benign location precluded the hydrocephalic and feared sudden death complications; thus, removal was not attempted. Either microsurgical or endoscopic removal will follow recurrence of signs and symptoms known to be caused by the tumor presumably due to migration back to its original location. * Miki Katzir m_katzir@rambam.health.gov.il

Pediatric colloid cysts (CC) have a congenital origin, and yet, there are very few studies focussing exclusively on their occurrence in the pediatric population. Pediatric CC has been associated with more aggressive clinical and radiological patterns than their adult counterparts. In this study, undertaken on children with anterior third ventricular CC, excised using the interhemispheric transcallosal approach, the characteristic clinicoradiological features and management options are studied. Five pediatric patients (aged 16 years or less; mean age 13.8 years; mean duration of symptoms:7.6 months) out of 38 patients with CC operated between 1995 to 2009 were included. The clinical manifestations included those of raised intracranial pressure (n = 4); exacerbation of occipital headache on reading (n = 1); secondary optic atrophy (n = 3); and, drop attacks (n = 1). On computed tomography scan, the cyst was hyperdense, enhancing in two patients and not enhancing in three patients. All had bilateral lateral ventricular dilatation with periventricular lucency. On magnetic resonance imaging (n = 3), the cyst was T1 hypointense and T2 isointense in one, hyperintense on both T1 and T2 with a hypointense capsule and nonenhancing on contrast in one (with a giant colloid cyst), and T1 hyperintense and T2 hypointense in one patient. An interhemispheric, transcallosal trajectory combined with transforminal approach (n = 3); combined transforminal and subchoroidal approaches (n = 1); and, interforniceal approach (n = 1) were used. Total excision was performed in four patients. In one patient, a small part of capsule was left attached to thalamostriate vein. Symptoms of raised intracranial pressure showed improvement in all the patients with resolution of hydrocephalus. There was no tumor recurrence at follow-up. Pediatric colloid cysts are rarer than their adult counterparts due to their late detection only after manifestations of raised intracranial pressure, visual or cognitive dysfunction or drop attacks occur. Their radiological appearance varies depending upon the amount of mucoid content, cholesterol, proteins, and water content. The fast development of clinical manifestations in children may be related to rapid enlargement of cyst due to higher water content within them. The transcallosal approach is the “gold standard” of surgery and usually ensures gratifying and lasting results.

Having just celebrated the centenary of the first transsphenoidal pituitary operation by (Schloffer in Austria in Beitr Klin Chir 50:767-817, 1906), and this year the quarter centenary of the first published report of a therapeutic use of the neuroendoscope (for colloid cysts of the third ventricle) (Powell et al. in Neurosurgery 13:234-237, 1983), it is time to consider the relative merits of microscopic and endoscopic approaches for pituitary surgery. Although transsphenoidal endoscopic surgery has only been utilised by pioneers such as Jho since the mid-1990s (Jho et al., 1996), there is no doubt that it has already gained an important place in the neurosurgical armamentarium, but there is both confusion and propaganda about which method of surgery has most to offer, and indeed whether or not there is any real difference at all.

The authors report a case of a huge colloid cyst of the septum pellucidum with acute worsening. A 42-year-old man was admitted for unexplained lethargy. A brain CT scan disclosed a huge intra-ventricular lesion. He experienced a sudden deterioration with coma, and was managed with bilateral ventricular external shunting. Total removal was performed a few days later using a right frontal trans-ventricular approach. The discussion focuses on colloid cyst potential to mimic other intracranial lesions, rendering accurate diagnosis difficult and leading to possibly inappropriate management in similar cases.

Dear Editor, Neurenteric cysts are rare benign endodermal lesions of the central nervous system like the Rathke cleft and colloid cysts. Intracranial neurenteric cysts are rare, with less than 100 cases reported in literature, most of which are found in the posterior fossa. We discuss a rare case of an extradural neurenteric cyst with supratentorial and infratentorial extension, and review the embryogenesis and differential diagnosis based on imaging and histopathological features. A 20-year male presented with suboccipital headache and painless, progressive diminution of vision of both eyes of 2 months’ duration. He was counting fingers close to face, and bilateral papilledema was noted. Evaluation with CT scan and MRI of the brain revealed an extradural lesion in the left posterior fossa with extension into the temporal region across the tentorium (Fig. 1a). He underwent a left retromastoid suboccipital craniectomy which was extended into the temporal region. The cyst was completely extradural in location, easily separable from the overlying bone and underlying duramater, except in the region over the transverse sinus where it was adherent to the duramater. Near total excision of the cyst wall was performed, leaving behind a part of the wall which was not separable from the duramater overlying the transverse sinus. The cyst contained thick, yellowish fluid (Fig. 1b), which was sterile on pyogenic culture with no cholesterol crystals or macrophages on microscopic examination. The patient had an uneventful post operative recovery period. At 6 months follow-up, his vision in the right eye improved to finger counting at 2 m, while that in the left eye remained unchanged. On fundoscopy, bilateral optic atrophy was noted. CT scan performed at 6 months showed no evidence of recurrence of the lesion (Fig. 1d). Histopathology sections showed a cystic lesion lined by a single layer of ciliated tall columnar epithelium (Fig. 1e). There was focal squamous metaplasia. Other connective tissue or glial elements were not identified. Immunohistochemistry with cytokeratin showed intense cytoplasmic positivity (Fig. 1f) in lining cells, whereas glial fibrillary acidic protein was negative (Fig. 1g). The precise embryological origin of the intracranial neurenteric cyst is not known. Since the endoderm does not extend cranially farther than the clivus, the possible explanation for an intracranial neurenteric cyst is displacement of the endoderm from its normal location (nasopharyngeal, respiratory tract, or intestinal tract) to an ectopic position in the embryo. Harris et al. has attributed the occurrence of posterior fossa neurenteric cyst to disturbance in early gastrulation after the onset of primitive streak regression [3]. Graziani et al. proposed that neurenteric cyst, colloid cyst, and Rathke cleft cyst originate from Seessel’s pouch, an endoderm diverticulum found behind esophageal membrane that usually regresses and disappears [2]. The evidence in support of this theory is that intracranial neurenteric cysts are not associated with other developmental malformations unlike spinal neurenteric cysts that are associated with occult spinal dysraphisms. The authors declare that this case report has not been presented at any conference or accepted for publication in any journal before. R. S. Reddy (*) :M. Vijayasaradhi Department of Neurosurgery, Nizam’s Institute of Medical Sciences, Hyderabad, Andhra Pradesh, India 500082 e-mail: rajesh_jipmer@rediffmail.com

¶ Four patients harbouring a colloid cyst of the 3rd ventricle were operated on endoscopically. With the “classical” monoportal technique, through a precoronal burr hole only partial removal could be achieved in the first case. As the crucial point of the procedure is the safe dissection of the cyst from the thela chorioidea and from the internal cerebral veins, adequate control of the posterior rim of the foramen of Monro and the roof of the 3rd ventricle is mandatory. Accordingly in other three cases a CT-guided biportal endoscopic technique was applied, which permitted radical removal of the entire cyst with maximum safety. CT-guidance is essential for optimal planning after careful study of the individual anatomy. In this way the rigid scopes are moved exclusively along their own axes throughout the procedure, the resulting brain damage thereby being minimal. With regard to all circumstances of the procedure, the use of flexible endoscopes appears to be inappropriate and biportal endoscopy offers itself as the method of choice.

Colloid cysts of the third ventricle have been investigated by chemical characterization of the cyst contents using ELISA with monoclonal antibodies for certain carbohydrate epitopes as well as a polyclonal antiserum against peptide domains, and immunohistochemistry on the cyst wall using the same antibodies. Furthermore, the carbohydrate composition of one sample has been determined after gel filtration. The cyst contents reacted strongly with the monoclonal antibody for the sulfo-Lewis(a) epitope, and with the antimucin polyclonal antiserum. In one case the cyst fluid exhibited a blood group A antigen. A sample of cyst wall obtained by biopsy showed strong immunoreactivity against sulfo-Lewis(n) antigen, and the sialo-Lewis(a) antigen. The presence of the S atom with its high atomic number relative to that of C, H, and O atoms, may contribute to the high density appearance of colloid cysts on CT-scans. The sulfo-Lewis(a) and sialo-Lewis(a) carbohydrate epitopes are known as ligands for selectins, involved in inflammatory processes, and may well account for the aseptic meningeal reaction that may follow spilling of cyst contents during operative evacuation. The carbohydrate epitopes exhibited by colloid cysts and their contents, have also been reported for the mucins of salivary glands, uterine cervix, gall bladder and colon, and therefore, are not inconsistent with the assumption of an endodermal origin of colloid cysts.

In order to avoid invasive procedures (transfrontal, transcallosal) in the surgical treatment of colloid cysts the stereotactic aspiration technique was introduced by Bosch, Rähn and Backlund in 1978. The viscosity of the intracystic colloid and the displacement of the cyst away from the aspiration needle are possible reasons for unsuccessful aspiration. GT-guided stereotactic endoscopic technique gives the opportunity to fenestrate the cyst wall under direct visual control. After CT-guided stereotactic puncture of the right lateral ventricle with the foramen of Monro as target a steerable endoscope is introduced and the foramen of Monro is passed. The wall of the cyst is fenestrated and coagulated by means of monopolar (or laser) coagulation. Using this technique we have treated four patients with colloid cysts. Immediately postoperatively all of them were relieved of their complaints and have been symptom-free for a mean follow up period of twelve months. Studies of cerebrospinal fluid flow patterns, performed prior to and every six months after the endoscopic intervention, confirmed a remarkable reduction of foraminal obstruction.

The surgical technique and clinical results for a series of 16 consecutive patients who underwent resection of third ventricular colloid cysts through a stereotactically guided cylindrical retractor are presented.Between March 1993 and December 2002, 16 patients, 11 males and 5 females with a mean age of 36, were admitted with colloid cysts of the third ventricle. Four patients had undergone previous surgery, of which two were simple aspirations, one endoscopic aspiration, and one transcallosal partial removal. Four patients required emergency ventriculostomies on admission. In all patients the foramen of Monro was targeted using a Leksell stereotactic frame. A coronal craniotomy three to four cm in diameter was performed and a cylindrical retractor 14 mm in diameter was advanced to the target. Microsurgical removal of the cyst was then performed through the retractor.Total removal of the cyst was achieved in all cases. Median follow-up time is 42 months. Complete resolution of symptoms occured in all patients. Control magnetic resonance imaging revealed no residual cysts. All patients have returned to their previous occupations without sequelae or epilepsy.The outcome obtained in this series has shown that transfrontal transforaminal total removal of colloid cysts through a stereotactically guided cylindrical retractor is a safe procedure.

The clinical and x-ray features of 28 cases of colloid cyst of the third ventricle are described. Colloid cyst is one of the most favourable space-occupying lesions of the brain for successful surgical removal, because an exact pre-operative diagnosis is possible. The surgical approach for colloid cyst of the third ventricle is discussed and the frequency of postoperative seizure is reviewed in 28 cases and compared with the literature.

Two cases of entirely suprasellar cysts are reported. Total surgical removal was performed in both cases. Pathological and immunohistochemical profiles were consistent with neurenteric cysts, Rathke's cleft cysts or colloid cysts and was also in keeping with an endodermal origin. It is now admitted that these three kinds of cysts share similar histological and immunohistological features. We propose an hypothesis of common embryological origin from endodermal remnants.

A review is given on the operative management of anterior third ventricle tumours, with special emphasis on the selection of the approach, the postoperative results and complications. The review is based on our own experiences with 337 cases and 340 operations, among them 198 craniopharyngiomas, 80 gliomas, 23 colloid cysts, 11 ependymomas, and 25 others. The tumours can be approached through the lamina terminals or transcallosally or using a combination of both of these approaches. The approach through the lamina terminalis is useful only in rather small tumours, because it does not allow a sufficient revision of the upper and posterior third ventricle compartments. For larger tumours the transcallosal approach is preferable. We have abandoned the approach through the anterior horn of the lateral ventricle, because it does not allow an equally good vision of both sides of the third ventricle. In some of the craniopharyngioma cases it was necessary to combine the transcallosal and subfrontal approaches in order to achieve total or subtotal tumour resection. In craniopharyngiomas total or subtotal tumour removal was possible in 66% of the children and 59% of the adult patients, with a mortality higher in adults (30%) than in children (18.5%). The main causes of complications in craniopharyngiomas were acute disturbances of hypothalamic circulation and function, with water-electrolyte imbalance and other signs of diencephalic insufficiency. In glioma cases an additional important cause of complications has been haemorrhage into the remaining tumour parts. Colloid cysts could be exstirpated without mortality, using the transcallosal approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Nineteen epithelial cysts in the central nervous system including six colloid cysts of the third ventricle, seven Rathke's cleft cysts in the sella, two enterogenous cysts in the posterior fossa, two epithelial cysts in the spinal canal and two neuroectodermal cysts in the cerebrum were examined immunohistochemically for expression of intermediate filament proteins-simple type, stratified type and skin type cytokeratins and GFAP. Colloid cysts of the third ventricle, Rathke's cleft cysts in the sella and epithelial cysts in the spinal canal expressed complex type cytokeratins while enterogenous cysts and neuro-ectodermal cysts showed only simple type cytokeratins. In addition, Rathke's cleft cysts expressed GFAP in occasional lining cells. The characteristic composition and distribution of cytokeratins in various kinds of epithelial cysts in the central nervous system are demonstrated and discussed with regard to their origins.

The techniques of stereotactic biopsy of mass lesions of the brain are described, and the indications are discussed. Since computerized axial tomography has become available the decision to perform a stereotactic biopsy is made more frequently than previously. Stereotactic techniques for neuro-oncology are a continously expanding field of largely diagnostic and sometimes therapeutic prodecures. It now seems likely that most centres concerned with brain tumour patients will make use of stereotactic biopsies in the future. A series of 60 stereotactic biopsies performed in the management of otherwise inaccessible tumours of the brain is presented.

The authors report on four unusual cases of chronic adult hydrocephalus extracted from a large personal series of patients with hydrocephalic dementia. A syndrome resembling that of normal pressure hydrocephalus was due to the following aetiologies in these patients: Paget's disease of the skull, unruptured cerebral arteriovenous malformation, colloid cyst of the third ventricle, and cerebromeningeal cysticercosis. All these patients exhibited disturbances in cerebrospinal fluid dynamics at the time of study, and were considerably improved by CSF shunting. The value of the continuous CSF pressure monitoring and the constant infusion test in selecting patients with chronic hydrocephalus for shunt therapy is emphasized.

Colloid cysts of the third ventricle can cause hydrocephalus if they grow to the point where they occlude the foramina interventricularia. The operative approach via a craniotomy used to be the common method of treating these lesions. Now, in the era of CT- and MR-scanning, stereotactic aspiration should be preferred as an ideal method of simultaneously diagnosing and treating colloid cysts. Unlike open surgery, aspiration of colloid masses poses hardly any risk for the patient. Ten cases successfully treated by this technique are presented.

Primary intraventricular tumors, including colloid cysts, choroid plexus papillomas, and ependymomas have their attachment within the IIIrd ventricle and stay within its confines. Secondary intraventricular tumours arise adjacent to the IIIrd ventricle, often in the suprasellar region, and include craniopharyngiomas, optic nerve gliomas, and meningiomas. Approaches to the ventricle include subfrontal, subtemporal, anterior transventricular, anterior and posterior transcallosal, and transtentorial routes. Memory problems have been noted with anterior dorsal methods, implicating damage to one or both anterior forniceal columns. Methods of opening the roof of the third ventricle must evaluate risk to the deep ventricular veins, the fornix, and the choroid plexus. The basal subfrontal method may be modified by opening the lamina terminalis or including a lateral approach from the pterional area. The application of these approaches in a series of 100 third ventricle tumours is analyzed.

Thirty-six colloid cysts were treated from 1949 to 1983. There were 26 male and 10 female patients, ranging in age from 12 to 65 years old, 60% between 31 and 40 years. Headache or disturbed mental function was the most frequent complaint, papilloedema the most frequent sign. The patients were classified into 3 groups by symptoms and signs; Group I (17 patients): Headache, papilloedema and no neurological signs. Group II (6 patients): Fluctuating or progressive dementia. Group III: Twelve cases with "classical" features, episodic headache and drop attacks. One patient could not be classified in any of these groups. Seventeen of 36 patients were diagnosed by ventriculography, 19 patients were diagnosed by CT scan. CT scan was the most reliable diagnostic study, but was unavailable in the earlier part of the series. All patients have been operated by transventricular exposure of the right foramen of Munro with incision of the middle frontal gyrus in an antero-posterior linear manner. Twenty-five of 36 patients showed an excellent operative result, and nine had a good result, one of the 9 patients dying of an unrelated intracerebral haemorrhage 4 years after operation. Two patients had a poor result, characterized by memory loss and confusion. One of these died of an unknown cause 5 years after operation.

Report of a case with spasmotic torticollis caused by a colloid cyst of the third ventricle. The torticollis disappeared immediately after removal of the cyst.