Juraj Šteňo

Tumor-Third Ventricular Relationships in Supradiaphragmatic Craniopharyngiomas: Correlation of Morphological, Magnetic Resonance Imaging, and Operative Findings

OBJECTIVE:To disclose the relationships of primarily supradiaphragmatic craniopharyngiomas with the third ventricular floor (3rdVF) by means of preoperative magnetic resonance imaging (MRI) and thus to select the surgical approach avoiding the hypothalamic structures. METHODS:MRI findings in 76 consecutive patients with craniopharyngiomas operated on between June 1991 and December 2002 were interpreted on the basis of the results of the authors’ own previous microanatomic studies. The assumed tumor-3rdVF relationships were then correlated with the operative findings. MRI features characteristic for different topographical relationships were analyzed in 44 patients (18 children, 26 adults) with exclusively supradiaphragmatic tumors. RESULTS:In 14 of 15 patients with the tumor located below the 3rdVF (suprasellar extraventricular craniopharyngioma), the anterior communicating artery was displaced upward and indirectly indicated the position of the chiasm between the prechiasmatic and the retrochiasmatic tumor portions. Hydrocephalus was absent in 14 patients, including those with giant tumors. The anterior part of the third ventricular cavity was found in front of the level of the foramina of Monro in 6 patients. All 28 tumors growing partially inside and partially outside the third ventricular cavity (intraventricular and extraventricular craniopharyngioma) were retrochiasmatic. They caused severe or moderate hydrocephalus in 20 patients and mild hydrocephalus in 2. One purely intraventricular tumor caused severe hydrocephalus. CONCLUSION:The position of the optic chiasm and the size of the lateral ventricles on preoperative MRI enable us to determine the position of the 3rdVF or its remnants in relation to the supradiaphragmatic craniopharyngiomas and to select the proper surgical approach allowing exposure of the tumor while avoiding the hypothalamic structures.

Microsurgical Topography of Craniopharyngiomas

The relationship of craniopharyngiomas to surrounding structures was studied by stereoscopic and light microscopy in 30 autopsies. The localization of 4 of the tumors was intra- and suprasellar, 26 lesions were primarily suprasellar. Suprasellar craniopharyngiomas were divided into three groups according to their relationship to the floor of the third ventricle: extraventricular, intra extraventricular and intraventricular. The different localization of craniopharyngiomas in the vertical axis is a codeterminant of the direction and extent of tumor growth in the horizontal plane at the base of the brain. Comparison of these anatomical data and additional anatomical findings obtained in primary microsurgical operations of another 16 patients with the results of plain X-ray and contrast studies revealed radiological features characteristic of different topographic groups. The choice of the most adequate approach and degree of radicality of surgery for craniopharyngiomas can be based on the results of pre-operative neuroradiological investigations.

Craniopharyngiomas in children: how radical should the surgeon be?

PurposeTwo main modes of management of craniopharyngiomas, namely, radical tumor removal and intentional incomplete removal followed by radiotherapy, are used. Recently, a half-way solution was added. Radical removal is reserved only for the tumors not involving hypothalamus. Such tumors, however, are not clearly defined. The goal of the study was to clarify the relationship of craniopharyngiomas with surrounding structures, especially hypothalamus, and to evaluate its clinical significance.MethodsOur policy of management of craniopharyngiomas was elaborated on the basis of the results of morphological studies of the topography and their correlation with magnetic resonance imaging (MRI) in 115 adults and children operated on since 1991. Suitability of the policy in children and adolescents was verified by long-term outcome analysis in 41 consecutive patients.ResultsThe rate of morbidity and mortality was higher in patients with craniopharyngiomas located inside the third ventricle either partially (intraventricular and extraventricular craniopharyngiomas, IEVCs, 16 patients) or completely (intraventricular, one patient) than in tumors located outside the ventricle (suprasellar extraventricular, SEVCs, five patients; intrasellar and suprasellar, 19 patients). Postsurgical hypothalamic signs and symptoms occurred most often in intraventricular tumors; there were no mental disorders or obesity caused by primary removal of SEVCs including those severely compressing hypothalamus.ConclusionsRadical removal of SEVCs is safer than of IEVCs despite an apparent involvement of hypothalamus. In majority of cases, they may be distinguished by indirect MRI signs; in others only according to operation findings; final decision about the optimal extent of tumor removal should be made during surgery.

MR imaging of late radiation therapy- and chemotherapy-induced injury: a pictorial essay

Radiation to the brain and adjuvant chemotherapy may produce late delayed changes from several months to years after treatment of intracranial malignancies with a reported prevalence of 5–24%. The pattern of treatment-related injury may vary from diffuse periventricular white matter lesions to focal or multifocal lesions. Differentiation of treatment-related injury from tumor progression/recurrence may be difficult with conventional MR imaging (MRI). With both disease processes, the characteristic but nonspecific imaging features are vasogenic edema, contrast enhancement, and mass effect. This pictorial essay presents MRI spectra of late therapy-induced injuries in the brain with a particular emphasis on radiation necrosis, the most common and severe form. Novel MRI techniques, such as diffusion-weighted imaging (DWI), proton MR spectroscopy (MRS), and perfusion MRI, improve the possibilities of better characterization of treatment-related changes. Advanced MRI techniques allow for the assessment of metabolism and physiology and may increase specificity for therapy-induced changes.

Persisting embryonal infundibular recess

Persisting embryonal infundibular recess (PEIR) is a rare anomaly of the third ventricular floor that has an unclear pathogenesis. In all 7 previously described cases, PEIR was present in adult patients and was invariably associated with hydrocephalus and, in 4 reported cases, with an empty sella. These associated findings led to speculations about the role of increased intraventricular pressure in the development of PEIR. In the present case, PEIR was found in a 24-year-old man without the presence of hydrocephalus or empty sella. Disorders of pituitary function had been present since childhood. Magnetic resonance imaging revealed a cystic expansion in an enlarged sella turcica. A communication between the third ventricle and the sellar cyst was suspected but not apparent. During transcranial surgery, the connection was confirmed. Later, higher-quality MR imaging investigations clearly showed a communication between the third ventricle and the sellar cyst through a channel in the tubular pituitary stalk. This observation and knowledge about the embryology of this region suggests that PEIR may be a developmental anomaly caused by failure of obliteration of the distal part of primary embryonal diencephalic evagination. Thus, PEIR is an extension of the third ventricular cavity into the sella. Although PEIR is a rare anomaly, it is important to identify when planning a procedure on cystic lesions of the sella. Because attempts at removal using the transsphenoidal approach would lead to a communication between the third ventricle and the nasal cavity, a watertight reconstruction of the sellar floor is necessary.

Direct electrical stimulation of the optic radiation in patients with covered eyes.

Direct electrical stimulation (DES) of the optic radiation (OR) during an awake tumor resection has been repeatedly reported. In all cases, visual function monitoring was performed in patients with open eyes which were looking at a picture. We report a new modification of the standard method, OR stimulation in patient with closed and covered eyes. To the best of our knowledge, this method was not presented before. According to our first experience, this methodology may be in some cases a potentially more sensitive form of neuromonitoring than the OR stimulation in patients with open eyes, as the phosphenes elicited by DES may be more distinct in patients with covered eyes. The technique is discussed, and a literature review on intraoperative identification of the OR is presented as well. However, a future prospective study is needed to confirm the relevance of our finding.

Visualization of lenticulostriate arteries during insular low-grade glioma surgeries by navigated 3D ultrasound power Doppler: technical note.

OBJECTIVE Resection of insular gliomas is challenging. In cases of intraoperative injury to the lenticulostriate arteries (LSAs), the usual result is a dense hemiplegia. LSAs are usually localized just behind the medial tumor border but they can also be encased by the tumor. Thus, exact localization of these perforators is important. However, intraoperative localization of LSAs using conventional neuronavigation can be difficult due to brain shift. In this paper, the authors present a novel method of intraoperative LSA visualization by navigated 3D ultrasound (3DUS) power Doppler. This technique enables almost real-time imaging of LSAs and evaluation of their shift during insular tumor resections. METHODS Six patients harboring insular Grade II gliomas were consecutively operated on at the Department of Neurosurgery in Bratislava using visualization of LSAs by navigated 3DUS power Doppler. In all cases, the 3DUS data were repeatedly updated to compensate for the brain shift and display the actual position of LSAs and residual tumor. RESULTS Successful visualization of LSAs was achieved in all cases. During all surgeries, the distance between the bottom of the resection cavity and LSAs could be accurately evaluated; in all tumors the resection approached the LSAs and only a minimal amount of tissue covering these perforators was intentionally left in place to avoid injury to them. CONCLUSIONS Visualization of LSAs by navigated 3DUS power Doppler is a useful tool that may help to prevent injury of LSAs during removal of insular low-grade gliomas. However, reliability of this method has to be carefully evaluated in further studies.

Pineal Region Teratomas in Children

Immature or mixed mature/immature teratomas of the pineal region were removed radically in three children. After a period of 26 and 25 months, two patients with immature teratomas are alive and well, whereas in the third patient a mixed teratoma locally recurred and caused a fatal rise of intracranial pressure 11 months after the operation. Regular examinations of tumor markers and neuroradiological investigations are mandatory after radical surgery and adjuvant radio- and chemotherapy.

Intraspinal extradural variations of nerve roots

INTRODUCTION The aim of this work is to point out the intraspinal extradural anatomical variations of nerve roots and their possible participation in radiculopathy. METHODS The anatomical study was performed in 33 cadavers at a mean age of 46.5 and up to 24h from death. All extradural anastomoses between nerve roots were excised and examined histologically for the presence or absence of nervous tissue. The type of the plexus was defined by subtracting from the root C2. RESULTS Findings with the normotype of plexus formation prevailed in 24 cases (72.7%). Variations in its formation were observed in 9 cases (27.3%). The prefixed type in 6 cases (18.2%), post-fixed type in 3 cases (9.1%). We did not observe the formation of the isolated prefixed or post-fixed types in the brachial or lumbosacral plexuses. Extradural anatomical variations occurred in 20 cases (60.6%). They were more frequent on the left, in 10 cases (30.3%), bilateral in 3 cases (9.1%). In 8 instances (24.2%), the atypical spacing, including four in the lumbosacral region, was observed. Variations occurred more frequently in variations of formation of the plexus. CONCLUSIONS This study allowed us to identify and describe unpublished intraspinal extradural anatomical variations of nerve roots and their interrelationships throughout the spinal canal with their potential influence on the clinical picture. Anatomical preparations revealed a higher incidence of intraspinal extradural variations, mainly between sacral roots. The reliance of their incidence of the type of plexus was observed.

Skull Base Involvement in Pituitary Adenomas

Pituitary adenomas which infiltrate their dural envelope sometimes perforate it and invade the neighboring structures: the sphenoid sinus, the cancellous bone of the clivus, the cavernous sinus, or the intracranial spaces. Radical removal of such invasive adenomas is problematic, their endocrinological cure is exceptional, and recurrence in nonirradiated patients is common (Guiot 1978). The evaluation and grading of invasiveness of pituitary adenomas are based on the radiological appearance of bony structures of the sella (Hardy 1982).