Comparison of the transvermian and telovelar approaches to the fourth ventricle

2004 ◽  
Vol 101 (3) ◽  
pp. 484-498 ◽  
Author(s):  
Necmettin Tanriover ◽  
Arthur J. Ulm ◽  
Albert L. Rhoton ◽  
Alexandre Yasuda
Keyword(s):  
Fourth Ventricle ◽  
Image Guidance ◽  
Surgical Approaches ◽  
Content Type ◽  
Lateral Recess ◽  
Telovelar Approach ◽  
Additional Exposure ◽  
Formalin Fixed ◽  
Fine Print ◽  
Foramen Of Luschka

Object. The two most common surgical routes to the fourth ventricle are the transvermian and telovelar approaches. The purpose of this study was to compare the microanatomy and exposures gained through these approaches. Methods. Ten formalin-fixed specimens were dissected in a stepwise manner to simulate the transvermian and telovelar surgical approaches. Stealth image guidance was used to compare the exposures and working angles obtained using these approaches. The transvermian and telovelar approaches provided access to the entire rostrocaudal length of the fourth ventricle floor from the aqueduct to the obex. In addition, both approaches provided access to the entire width of the floor of the fourth ventricle. The major difference between the two approaches regarded the exposure of the lateral recess and the foramen of Luschka. The telovelar, but not the transvermian, approach exposed the lateral and superolateral recesses and the foramen of Luschka. The transvermian approach, which offered an incision through at least the lower third of the vermis, afforded a modest increase in the operator's working angle compared with the telovelar approach when accessing the rostral half of the fourth ventricle. Conclusions. The transvermian approach provides slightly better visualization of the medial part of the superior half of the roof of the fourth ventricle. The telovelar approach, which lacks incision of any part of the cerebellum, provides an additional exposure to the lateral recesses and the foramen of Luschka.

Telovelar approach to the fourth ventricle: microsurgical anatomy

2000 ◽  
Vol 92 (5) ◽  
pp. 812-823 ◽  
Author(s):  
Antonio C. M. Mussi ◽  
Albert L. Rhoton
Keyword(s):  
Fourth Ventricle ◽  
Microsurgical Anatomy ◽  
Thin Sheets ◽  
Content Type ◽  
Lateral Recess ◽  
The Past ◽  
Tela Choroidea ◽  
Telovelar Approach ◽  
Formalin Fixed ◽  
Fine Print

Object. In the past, access to the fourth ventricle was obtained by splitting the vermis or removing part of the cerebellum. The purpose of this study was to examine the access to the fourth ventricle achieved by opening the tela choroidea and inferior medullary velum, the two thin sheets of tissue that form the lower half of the roof of the fourth ventricle, without incising or removing part of the cerebellum.Methods. Fifty formalin-fixed specimens, in which the arteries were perfused with red silicone and the veins with blue silicone, provided the material for this study. The dissections were performed in a stepwise manner to simulate the exposure that can be obtained by retracting the cerebellar tonsils and opening the tela choroidea and inferior medullary velum.Conclusions. Gently displacing the tonsils laterally exposes both the tela choroidea and the inferior medullary velum. Opening the tela provides access to the floor and body of the ventricle from the aqueduct to the obex. The additional opening of the velum provides access to the superior half of the roof of the ventricle, the fastigium, and the superolateral recess. Elevating the tonsillar surface away from the posterolateral medulla exposes the tela, which covers the lateral recess, and opening this tela exposes the structure forming the walls of the lateral recess.

Transcerebellomedullary fissure approach with special reference to the methods of dissecting the fissure

2001 ◽  
Vol 94 (2) ◽  
pp. 257-264 ◽  
Author(s):  
Toshio Matsushima ◽  
Tooru Inoue ◽  
Takanori Inamura ◽  
Yoshihiro Natori ◽  
Kiyonobu Ikezaki ◽  
...  
Keyword(s):  
Fourth Ventricle ◽  
Posterior Margin ◽  
Lateral Wall ◽  
Microsurgical Anatomy ◽  
Optimal Method ◽  
Content Type ◽  
Lateral Recess ◽  
Tela Choroidea ◽  
Opening Method ◽  
Fine Print

Object. The purpose of the present study was to refine the transcerebellomedullary fissure approach to the fourth ventricle and to clarify the optimal method of dissecting the fissure to obtain an appropriate operative view without splitting the inferior vermis. Methods. The authors studied the microsurgical anatomy by using formalin-fixed specimens to determine the most appropriate method of dissecting the cerebellomedullary fissure. While dissecting the spaces around the tonsils and making incisions in the ventricle roof, the procedures used to expose each ventricle wall were studied. Based on their findings, the authors adopted the best approach for use in 19 cases of fourth ventricle tumor. The fissure was further separated into two slit spaces on each side: namely the uvulotonsillar and medullotonsillar spaces. The floor of the fissure was composed of the tela choroidea, inferior medullary velum, and lateral recess, which form the ventricle roof. In this approach, the authors first dissected the spaces around the tonsils and then incised the taenia with or without the posterior margin of the lateral recess. These precise dissections allowed for easy retraction of the tonsil(s) and uvula and provided a sufficient view of the ventricle wall such that the deep aqueductal region and the lateral region around the lateral recess could be seen without splitting the vermis. The dissecting method could be divided into three different types, including extensive (aqueduct), lateral wall, and lateral recess, depending on the location of the ventricle wall and the extent of surgical exposure required. Conclusions. When the fissure is appropriately and completely opened, the approach provides a sufficient operative view without splitting the vermis. Two key principles of this opening method are sufficient dissection of the spaces around the tonsil(s) and an incision of the appropriate portions of the ventricle roof. The taenia(e) with or without the posterior margin of the lateral recess(es) should be incised.

Intraventricular hemorrhage due to aneurysms of the distal posterior inferior cerebellar artery

1985 ◽  
Vol 62 (5) ◽  
pp. 772-775 ◽  
Author(s):  
Hwa-Shain Yeh ◽  
Thomas A. Tomsick ◽  
John M. Tew
Keyword(s):  
Fourth Ventricle ◽  
Intraventricular Hemorrhage ◽  
Surgical Repair ◽  
Posterior Inferior Cerebellar Artery ◽  
Content Type ◽  
Lateral Recess ◽  
Cerebellar Artery ◽  
Subarachnoid Blood ◽  
Basal Cisterns ◽  
Fine Print

✓ Three cases of ruptured aneurysm of the distal posterior inferior cerebellar artery (PICA) presenting with isolated intraventricular hematoma are reported. All of the aneurysms originated from the lateral medullary segment of the PICA and ruptured into the lateral recess of the fourth ventricle. The diagnosis of distal PICA aneurysm should be considered if isolated intraventricular hematoma is found without obvious parenchymal hemorrhage or subarachnoid blood in the basal cisterns. Complete vertebral arteriography is a requisite for the recognition of this condition. The outcome in patients with these aneurysms should be good if surgical repair is performed before rebleeding occurs.

Hydrocephalus due to idiopathic stenosis of the foramina of Magendie and Luschka

2003 ◽  
Vol 98 (4) ◽  
pp. 897-902 ◽  
Author(s):  
Carine Karachi ◽  
Caroline Le Guérinel ◽  
Pierre Brugières ◽  
Eliane Melon ◽  
Philippe Decq
Keyword(s):  
Fourth Ventricle ◽  
Third Ventricle ◽  
Ventricular Volume ◽  
Transverse Diameter ◽  
Type I ◽  
Content Type ◽  
Chiari Type I Malformation ◽  
Chiari Type I ◽  
Fine Print ◽  
Foramen Of Luschka

✓ Idiopathic stenosis of the foramina of Magendie and Luschka is a rare cause of obstructive hydrocephalus involving the four ventricles. Like other causes of noncommunicating hydrocephalus, it can be treated with endoscopic third ventriculostomy (ETV). Three patients who were 21, 53, and 68 years of age presented with either headaches (isolated or associated with raised intracranial pressure) or vertigo, or a combination of gait disorders, sphincter disorders, and disorders of higher functions. In each case, magnetic resonance (MR) imaging demonstrated hydrocephalus involving the four ventricles (mean transverse diameter of third ventricle 14.15 mm; mean sagittal diameter of fourth ventricle 23.13 mm; and mean ventricular volume 123.92 ml) with no signs of a Chiari Type I malformation (normal posterior fossa dimensions, no herniation of cerebellar tonsils). The diagnosis of obstruction was confirmed using ventriculography (in two patients) and/or MR flow images (in two patients). All patients presented with marked dilation of the foramen of Luschka that herniated into the cisterna pontis. All patients were treated using ETV. No complications were observed. All three patients became asymptomatic during the weeks following the surgical procedure and remained stable at a mean follow-up interval of 36 months. Postoperative MR images demonstrated regression of the hydrocephalus (mean transverse diameter of third ventricle 7.01 mm; mean sagittal diameter of fourth ventricle 16.6 mm; and mean ventricular volume 79.95 ml), resolution of dilation of the foramen of Luschka, and good patency of the ventriculostomy (flow sequences). These results confirm the existence of hydrocephalus caused by idiopathic fourth ventricle outflow obstruction without an associated Chiari Type I malformation, and the efficacy of ETV for this rare indication.

Unusual causes of trigeminal neuralgia treated by gamma knife radiosurgery

2002 ◽  
Vol 97 ◽  
pp. 533-535 ◽  
Author(s):  
Jin Woo Chang ◽  
Jae Young Choi ◽  
Young Sul Yoon ◽  
Yong Gou Park ◽  
Sang Sup Chung
Keyword(s):  
Trigeminal Neuralgia ◽  
Gamma Knife ◽  
Fourth Ventricle ◽  
Gamma Knife Radiosurgery ◽  
Brain Magnetic Resonance Imaging ◽  
Resonance Imaging ◽  
Segmental Demyelination ◽  
Content Type ◽  
Clinical Responses ◽  
Fine Print

✓ The purpose of this paper was to present two cases of secondary trigeminal neuralgia (TN) with an unusual origin and lesion location. In two cases TN was caused by lesions along the course of the trigeminal nerve within the pons and adjacent to the fourth ventricle. Both cases presented with typical TN. Brain magnetic resonance imaging revealed linear or wedge-shaped lesions adjacent to the fourth ventricle, extending anterolaterally and lying along the pathway of the intraaxial trigeminal fibers. The involvement of the nucleus of the spinal trigeminal tract and of the principal sensory trigeminal nucleus with segmental demyelination are suggested as possible causes for trigeminal pain in these cases. It is postulated that these lesions are the result of an old viral neuritis. The patients underwent gamma knife radiosurgery and their clinical responses have been encouraging to date.

Teratoma of the fourth ventricle

1973 ◽  
Vol 38 (3) ◽  
pp. 355-357 ◽  
Author(s):  
Robert J. Morelli
Keyword(s):  
Fourth Ventricle ◽  
Rare Case ◽  
Surgical Removal ◽  
Malignant Teratoma ◽  
Content Type ◽  
Fine Print

✓ The author reports a rare case in which a primary malignant teratoma presented as an obstructing mass in the fourth ventricle. The tumor was not cystic but well encapsulated, and a gross total surgical removal was accomplished. A fatal recurrence occurred within 3 months.

Effect of frameless stereotaxy on the accuracy of C1–2 transarticular screw placement

2001 ◽  
Vol 95 (1) ◽  
pp. 74-79 ◽  
Author(s):  
Orin Bloch ◽  
Langston T. Holly ◽  
Jongsoo Park ◽  
Chinyere Obasi ◽  
Kee Kim ◽  
...  
Keyword(s):  
Image Guidance ◽  
Vascular Anatomy ◽  
Ct Scanning ◽  
Screw Placement ◽  
Frameless Stereotaxy ◽  
Transarticular Screw ◽  
Anterior Cortex ◽  
Content Type ◽  
Pars Interarticularis ◽  
Fine Print

Object. In recent studies some authors have indicated that 20% of patients have at least one ectatic vertebral artery (VA) that, based on previous criteria in which preoperative computerized tomography (CT) and standard intraoperative fluoroscopic techniques were used, may prevent the safe placement of C1–2 transarticular screws. The authors conducted this study to determine whether frameless stereotaxy would improve the accuracy of C1–2 transarticular screw placement in healthy patients, particularly those whom previous criteria would have excluded. Methods. The authors assessed the accuracy of frameless stereotaxy for C1–2 transarticular screw placement in 17 cadaveric cervical spines. Preoperatively obtained CT scans of the C-2 vertebra were registered on a stereotactic workstation. The dimensions of the C-2 pars articularis were measured on the workstation, and a 3.5-mm screw was stereotactically placed if the height and width of the pars interarticularis was greater than 4 mm. The specimens were evaluated with postoperative CT scanning and visual inspection. Screw placement was considered acceptable if the screw was contained within the C-2 pars interarticularis, traversed the C1–2 joint, and the screw tip was shown to be within the anterior cortex of the C-1 lateral mass. Transarticular screws were accurately placed in 16 cadaveric specimens, and only one specimen (5.9%) was excluded because of anomalous VA anatomy. In contrast, a total of four specimens (23.5%) showed significant narrowing of the C-2 pars interarticularis due to vascular anatomy that would have precluded atlantoaxial transarticular screw placement had previous nonimage-guided criteria been used. Conclusions. Frameless stereotaxy provides precise image guidance that improves the safety of C1–2 transarticular screw placement and potentially allows this procedure to be performed in patients previously excluded because of the inaccuracy of nonimage-guided techniques.

Fourth ventricular schwannoma

1990 ◽  
Vol 73 (5) ◽  
pp. 777-781 ◽  
Author(s):  
Gary Redekop ◽  
Kost Elisevich ◽  
Joseph Gilbert
Keyword(s):  
Fourth Ventricle ◽  
Content Type ◽  
Radiographic Features ◽  
Unusual Location ◽  
Pontomedullary Junction ◽  
Fine Print

✓ A schwannoma arising from the dorsum of the pontomedullary junction and presenting as an exophytic mass in the fourth ventricle is described. A ventricular schwannoma has not previously been reported in the literature. The presenting clinical and radiographic features and the pathology of this tumor are summarized, and an explanation is sought for its unusual location.

Intraoperative anatomical studies in patients with aneurysms of the anterior communicating artery complex

1992 ◽  
Vol 76 (4) ◽  
pp. 629-634 ◽  
Author(s):  
Edgar Nathal ◽  
Nobuyuki Yasui ◽  
Takeshi Sampei ◽  
Akifumi Suzuki
Keyword(s):  
Surgical Approach ◽  
Radical Surgery ◽  
Anatomical Variations ◽  
Surgical Approaches ◽  
Anterior Communicating Artery ◽  
Anatomical Studies ◽  
Content Type ◽  
Number Of Patients ◽  
Vascular Elements ◽  
Fine Print

✓ The intraoperative anatomical findings of the anterior communicating artery (ACoA) complex in 46 patients with anatomical variations were compared to those in an equal number of patients without variations in order to determine the visualization of the elements of the vascular complex. All patients underwent radical surgery for an ACoA aneurysm by one of three different surgical approaches: transsylvian, anterior interhemispheric, or basal interhemispheric. Visualization of the vascular elements was similar in patients with or without anatomical variations. The differences observed were dependent on the surgical approach selected and on the projection of the aneurysm. It was found that, even when the intraoperative anatomical field and the number of vascular elements visualized are different from those obtained in autopsy studies, the vascular microanatomical characteristics can be confirmed with each surgical approach to the extent necessary to ensure safe clipping of aneurysms in patients both with and without anatomical variations.

Transkull focal lesions in cat brain produced by ultrasound

1981 ◽  
Vol 54 (5) ◽  
pp. 659-663 ◽  
Author(s):  
Francis J. Fry ◽  
Stephen A. Goss ◽  
James T. Patrick
Keyword(s):  
Focused Ultrasound ◽  
Ultrasonic Beam ◽  
Acoustical Parameters ◽  
Focal Lesions ◽  
Content Type ◽  
Histological Appearance ◽  
Cat Brain ◽  
Ultrasonic Techniques ◽  
Formalin Fixed ◽  
Fine Print

✓ Focused ultrasound has been used for focal modifications of brain tissue and in preliminary studies of the application of ultrasonic techniques for tissue modification in human stereotaxic neurosurgery; however, the technique has been seriously compromised by the necessity of removal of intervening skull. Such removal was necessary to avoid distortion and extremely large attenuation of the ultrasonic beam which resulted from passage through bone. Recent studies have shown that under proper conditions focal beams of ultrasound can be transmitted with tolerable distortion and attenuation through skull, suggesting the possibility of transkull lesion production in brain. This report describes the acoustical parameters and histological features of focal brain lesions produced in 10 craniectomized cats with intense focal ultrasonic beams which first had passed through a formalin-fixed human skull overlay. The histological appearance of these lesions produced to date is similar to that produced previously without intervening skull.

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