Intraoperative identification of motor areas of the rhomboid fossa using direct stimulation

1993 ◽  
Vol 79 (3) ◽  
pp. 393-399 ◽  
Author(s):  
Christian Strauss ◽  
Johann Romstöck ◽  
Christopher Nimsky ◽  
Rudolf Fahlbusch
Keyword(s):  
Brain Stem ◽  
Fourth Ventricle ◽  
Complete Removal ◽  
Direct Stimulation ◽  
Content Type ◽  
Rhomboid Fossa ◽  
Stem Lesions ◽  
Mass Lesions ◽  
The Brain ◽  
Motor Areas

✓ Intraoperative electrical identification of motor areas within the floor of the fourth ventricle was successfully carried out in a series of 10 patients with intrinsic pontine lesions and lesions infiltrating the brain stem. Direct electrical stimulation was used to identify the facial colliculus and the hypoglossal triangle before the brain stem was entered. Multichannel electromyographic recordings documented selective stimulation effects. The surgical approach to the brain stem was varied according to the electrical localization of these structures. During removal of the lesion, functional integrity was monitored by intermittent stimulation. In lesions infiltrating the floor of the fourth ventricle, stimulation facilitated complete removal. Permanent postoperative morbidity of facial or hypoglossal nerve dysfunction was not observed. Mapping of the floor of the fourth ventricle identifies important surface structures and offers a safe corridor through intact nervous structures during surgery of brain-stem lesions. Reliable identification is particularly important in mass lesions with displacement of normal topographical anatomy.

A study of safe entry zones via the floor of the fourth ventricle for brain-stem lesions

1993 ◽  
Vol 78 (6) ◽  
pp. 987-993 ◽  
Author(s):  
Kazuhiko Kyoshima ◽  
Shigeaki Kobayashi ◽  
Hirohiko Gibo ◽  
Takayuki Kuroyanagi
Keyword(s):  
Facial Nerve ◽  
Brain Stem ◽  
Fourth Ventricle ◽  
Medial Lemniscus ◽  
Content Type ◽  
Brain Stem Lesions ◽  
Stem Lesions ◽  
Hazardous Procedure ◽  
The Brain ◽  
Fine Print

✓ Direct surgery for intra-axial lesions of the brain stem is considered a hazardous procedure, and morbidity of varying degrees cannot be avoided even with partial removal or biopsy. The main causes of morbidity relate to direct damage during removal of the lesion, selection of an entry route into the brain stem, and the direction of brain stem retraction. The authors examined the possibility of making a medullary incision and retracting the brain stem, taking into account the symptomatology and surgical anatomy, and found two safe entry zones into the brain stem through a suboccipital approach via the floor of the fourth ventricle. These safe entry zones are areas where important neural structures are less prominent. One is the “suprafacial triangle,” which is bordered medially by the medial longitudinal fascicle, caudally by the facial nerve (which runs in the brainstem parenchyma), and laterally by the cerebellar peduncle. The second is the “infrafacial triangle,” which is bordered medially by the medial longitudinal fascicle, caudally by the striae medullares, and laterally by the facial nerve. In order to minimize the retraction-related damage to important brain-stem structures, the brain stem should be retracted either laterally or rostrally in the suprafacial triangle approach and only laterally in the infrafacial triangle approach. Three localized intra-axial brain-stem lesions were treated surgically via the safe entry zones using the suprafacial approach in two and the infrafacial approach in one. The cases are described and the approaches delineated. Both approaches are indicated for focal intra-axial lesions located unilaterally and dorsal to the medial lemniscus in the lower midbrain to the pons. Magnetic resonance imaging is useful in selecting these approaches, and intraoperative ultrasonography is helpful to confirm the exact location of a lesion before a medullary incision is made. These approaches can also be used as routes for aspiration of brain-stem hemorrhage as well as for tumor biopsy.

Noninvasive localization of brain-stem lesions in the cat with multimodality evoked potentials

1981 ◽  
Vol 54 (6) ◽  
pp. 740-750 ◽  
Author(s):  
Richard P. Greenberg ◽  
Donald M. Stablein ◽  
Donald P. Becker
Keyword(s):  
Evoked Potentials ◽  
Brain Stem ◽  
Evoked Potential ◽  
Animal Experiments ◽  
Content Type ◽  
Central Nervous System Dysfunction ◽  
Multimodality Evoked Potentials ◽  
Stem Lesions ◽  
The Brain ◽  
Fine Print

✓ Multimodality evoked potential (MEP) data from over 300 comatose head-injured patients suggest that central nervous system dysfunction of the brain stem and/or hemispheres can be localized with this noninvasive neuroelectric technique. Based on this work, decerebrate motor posturing and prolonged coma are not associated with brain-stem dysfunction but rather with dysfunction of the hemispheres, while absent pupillary and oculocephalic responses are correlated with brain-stem dysfunction alone. However, the accuracy with which MEP data localized human brain-stem or hemispheric dysfunction could not be confirmed by pathological correlation because of low mortality and the small number of autopsies obtained in the patients who died. Therefore, this study was undertaken in an animal model of brain-stem lesion. Complete brain-stem transections were made at the cervicomedullary junction, the medulla just caudal to the eighth nerve, and at the intercollicular region. All cortical visual evoked potential (VEP) peaks were reduced in amplitude and delayed by each of the brain-stem transections, but none of the peaks was abolished. In spite of brain-stem transection, VEP's can be used to gain information about hemispheric function. Somatosensory (SEP) and auditory cortically generated evoked potentials (AEP) were abolished by these brain-stem transections, but early-latency brain-stem SEP and AEP data could accurately localize specific areas of brain-stem dysfunction caused by the lesions. Observations made on human MEP data seem to be confirmed by these animal experiments. Correlations between human and cat MEP data are discussed.

Surgical Resection of Intrinsic Brain Stem Lesions: An Overview

Neurosurgery ◽  
1990 ◽  
Vol 27 (5) ◽  
pp. 789-798 ◽  
Author(s):  
Dan S. Heffez ◽  
James S. Zinreich ◽  
Donlin M. Long
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Brain Stem ◽  
Magnetic Resonance Imaging Scan ◽  
Resonance Imaging ◽  
Aggressive Approach ◽  
Brain Stem Lesions ◽  
Stem Lesions ◽  
Mass Lesions ◽  
The Brain

Abstract A major limitation to the effective treatment of intrinsic mass lesions of the brain stem has been the inability to clearly define the pathological anatomy radiographically. The improved soft tissue resolution offered by magnetic resonance imaging, as compared with axial computed tomography, now makes it possible not only to accurately distinguish anatomical relationships, but also to predict the pathological nature of the lesion. Accordingly, we have been encouraged to pursue a more aggressive approach to intrinsic lesions of the brain stem that appear well circumscribed on magnetic resonance imaging scan. The object of this paper is to report the successfuly treatment of four intrinsic lesions of the brain stem and to present an overview of the relevant published experience.

Early descriptions of the Arnold-Chiari malformation

1972 ◽  
Vol 37 (5) ◽  
pp. 543-547 ◽  
Author(s):  
Peter W. Carmel ◽  
William R. Markesbery
Keyword(s):  
Brain Stem ◽  
Chiari Malformation ◽  
Fourth Ventricle ◽  
Cervical Canal ◽  
Content Type ◽  
Anatomical Features ◽  
John Cleland ◽  
Arnold Chiari Malformation ◽  
The Brain ◽  
Cerebellar Tonsils

✓ John Cleland described an unusual congenital anomaly of the brain stem in 1883 in which the medulla was elongated, the fourth ventricle extended into the cervical canal, and the inferior vermis distorted caudally. In 1891 Chiari described two types of brain stem malformation; in one the cerebellar tonsils extended into the cervical canal without medullary deformation, while in the other there was caudal extension of the brain stem and cerebellum and prolongation of the inferior vermis into the cervical canal. The second type was termed the “Arnold-Chiari” malformation by other authors in 1907, and corresponds to the condition described earlier by Cleland. The anatomical features and differences between the types of malformation are tabulated.

Brain-stem glioma growth patterns

1993 ◽  
Vol 78 (3) ◽  
pp. 408-412 ◽  
Author(s):  
Fred J. Epstein ◽  
Jean-Pierre Farmer
Keyword(s):  
Brain Stem ◽  
Growth Patterns ◽  
Brain Stem Glioma ◽  
Mr Images ◽  
Content Type ◽  
Fiber Tracts ◽  
Glioma Growth ◽  
Stem Lesions ◽  
The Brain ◽  
Brain Stem Gliomas

✓ During the last decade, several authors have reported that certain brain-stem gliomas may be associated with a better prognosis than others. In this paper, retrospective correlations between the pathological findings and the magnetic resonance (MR) imaging appearance of 88 brain-stem gliomas are established. The authors propose an anatomical hypothesis that helps identify glioma growth patterns in general and that clarifies why cervicomedullary, dorsally exophytic, and focal tumors have a more favorable prognosis. According to this hypothesis, growth of benign gliomas of the brain stem is guided by secondary structures such as the pia, fiber tracts, and the ependyma, which in turn leads to stereotypical growth patterns that are clearly identified on MR images. The authors believe that this hypothesis, in conjunction with clinical data, may help establish selection criteria for the surgical treatment of specific brain-stem lesions.

Stereotaxic biopsy of intrinsic lesions of the brain stem

1986 ◽  
Vol 65 (2) ◽  
pp. 172-176 ◽  
Author(s):  
Terry W. Hood ◽  
Stephen S. Gebarski ◽  
Paul E. McKeever ◽  
Joan L. Venes
Keyword(s):  
Brain Stem ◽  
Histological Diagnosis ◽  
High Yield ◽  
Content Type ◽  
Stereotaxic Biopsy ◽  
Brain Stem Lesions ◽  
Low Incidence ◽  
Stem Lesions ◽  
Permanent Neurological Deficit ◽  
The Brain

✓ Despite improved brain-stem imaging by magnetic resonance and high-resolution x-ray computerized tomography, definitive diagnosis and therapy of intrinsic lesions of the brain stem require histological verification. A stereotaxic approach to brain-stem lesions provides a high yield of positive histological diagnosis with a low incidence of morbidity. A series of 14 stereotaxic procedures performed on 12 patients with intrinsic lesions of the mesencephalon, pons, and medulla is reviewed. A detailed description of the transfrontal approach used by the authors is presented. Definitive pathological diagnosis was obtained in all patients. There was no operative mortality and only one case of permanent neurological deficit. The significance of accurate histological diagnosis in the therapy of brain-stem lesions is discussed.

Arteriovenous malformations in the posterior fossa

1977 ◽  
Vol 47 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Hiroshi Matsumura ◽  
Yasumasa Makita ◽  
Kuniyuki Someda ◽  
Akinori Kondo
Keyword(s):  
Arteriovenous Malformation ◽  
Brain Stem ◽  
Posterior Fossa ◽  
Arteriovenous Malformations ◽  
Cerebellopontine Angle ◽  
Anterior Part ◽  
Content Type ◽  
The Brain ◽  
Fine Print

✓ We have operated on 12 of 14 cases of arteriovenous malformation (AVM) in the posterior fossa since 1968, with one death. The lesions were in the cerebellum in 10 cases (three anteromedial, one central, three lateral, and three posteromedial), and in the cerebellopontine angle in two; in two cases the lesions were directly related to the brain stem. The AVM's in the anterior part of the cerebellum were operated on through a transtentorial occipital approach.

Cervical spinal cord in experimental hydrocephalus

1972 ◽  
Vol 37 (5) ◽  
pp. 538-542 ◽  
Author(s):  
George J. Dohrmann
Keyword(s):  
Spinal Cord ◽  
Brain Stem ◽  
Cervical Spinal Cord ◽  
Central Canal ◽  
Content Type ◽  
Experimental Hydrocephalus ◽  
Physiological Pressure ◽  
The Brain ◽  
Shunting Procedure ◽  
Fine Print

✓ Adult dogs were rendered hydrocephalic by the injection of kaolin into the cisterna magna. One group of dogs was sacrificed 1 month after kaolin administration, and ventriculojugular shunts were performed on the other group. Hydrocephalic dogs with shunts were sacrificed 1 day or 1 week after the shunting procedure. All dogs were perfused with formalin at physiological pressure, and the brain stem and cervical spinal cord were examined by light microscopy. Subarachnoid granulomata encompassed the superior cervical spinal cord and dependent surface of the brain stem. Rarefaction of the posterior white columns and clefts or cavities involving the gray matter posterior to the central canal and/or posterior white columns were present in the spinal cords of both hydrocephalic and shunted hydrocephalic dogs. Predominantly in the dogs with shunts, hemorrhages were noted in the spinal cord in association with the clefts or cavities. A mechanism of ischemia followed by reflow of blood is postulated to explain the hemorrhages in the spinal cords of hydrocephalic dogs with shunts.

Meningioangiomatosis of the brain stem

1994 ◽  
Vol 80 (4) ◽  
pp. 732-735 ◽  
Author(s):  
Spyros S. Kollias ◽  
Kerry R. Crone ◽  
William S. Ball ◽  
Erin C. Prenger ◽  
Edgar T. Ballard
Keyword(s):  
Brain Stem ◽  
Low Grade ◽  
Facial Weakness ◽  
Content Type ◽  
Weighted Image ◽  
Small Vessels ◽  
Body Magnetic Resonance Imaging ◽  
The Brain ◽  
Firm Mass

✓ The case is reported of meningioangiomatosis of the brain stem in a 3½-year-old girl who suffered from vomiting, left facial weakness, difficulty in swallowing, and ataxia. This is believed to be the first reported case of meningioangiomatosis in the brain stem. Computerized tomography showed an intensely enhancing hyperdense mass in the left restiform body. Magnetic resonance imaging revealed that the lesion was isointense to gray matter on the T1-weighted image and hypointense on the T2-weighted image, with a surrounding zone of high T2 signal and intense enhancement. Angiography was normal. Surgical exploration demonstrated an intramedullary firm mass that was partially resected. Histologically, the mass consisted of a low-grade lesion of meningeal origin with spindle cells in a whorling pattern that were occasionally focused around small vessels. On 2-year follow-up imaging, the lesion remains unchanged in size. Certain particularities of this lesion are discussed in the context of the literature.

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