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.

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.

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.

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.

Facial nerve preservation in patients with large acoustic neuromas treated by a combined middle fossa transtentorial translabyrinthine approach

1982 ◽  
Vol 57 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Charles H. Tator ◽  
Julian M. Nedzelski
Keyword(s):  
Facial Nerve ◽  
Brain Stem ◽  
Cerebellopontine Angle ◽  
Middle Fossa ◽  
Total Removal ◽  
Content Type ◽  
Translabyrinthine Approach ◽  
Acoustic Neuromas ◽  
The Brain ◽  
Fine Print

✓ With large acoustic neuromas, the primary goal of surgery is safe total removal of the tumors, and the secondary goal is preservation of nearby neural structures, including the facial nerve. In a series of 15 consecutive patients with large cerebellopontine angle tumors, all of which were more than 2.5 cm in diameter, tumor excision was performed by a one-stage combined middle fossa-translabyrinthine approach. There were 13 acoustic neuromas, 10 of which were more than 4 cm in diameter, one petrous apex meningioma 4 cm in diameter, and one facial neuroma 3 cm in diameter. The tumors were totally removed in all 15 patients. The facial nerve was preserved in 12 of 13 evaluable patients. In the 14th patient the nerve had been transected in a previous suboccipital procedure with incomplete removal, and in the 15th patient the nerve was sutured following excision of a facial neuroma. Thus, the nerve was lost at surgery in only one patient. This combined approach provided very clear visualization of the cerebellopontine angle, including the brain stem and the lower cranial nerves. It enabled identification of both the origin of the facial nerve at the brain stem and the lateral segment of the nerve in the internal auditory canal. Anterior extensions of tumor growing through the tentorial hiatus were easily removed. The results in these 15 patients show that this approach is excellent for total removal of large acoustic neuromas with preservation of the facial nerve. It is especially suitable for large tumors with anterior extensions.

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.

Medulla oblongata edema associated with neurogenic pulmonary edema

1986 ◽  
Vol 64 (3) ◽  
pp. 494-500 ◽  
Author(s):  
Robert H. Brown ◽  
Brian D. Beyerl ◽  
Richard Iseke ◽  
Michael H. Lavyne
Keyword(s):  
Pulmonary Edema ◽  
Brain Stem ◽  
Central Nervous System Disease ◽  
Neurogenic Pulmonary Edema ◽  
Anatomical Location ◽  
Content Type ◽  
Von Hippel Lindau ◽  
System Disease ◽  
Brain Stem Lesions ◽  
Stem Lesions

✓ Neurogenic pulmonary edema (NPE) occurs in association with central nervous system disease without underlying cardiopulmonary problems. It is characterized by profound pulmonary vascular congestion and a fulminant clinical course. Although several reports document a role for experimental brain-stem lesions in the production of NPE, there have been only two studies in man correlating specific brain-stem lesions with NPE. The authors report a case of NPE occurring in a patient with von Hippel-Lindau disease and a dorsal medullary syrinx with postoperative dorsal medullary edema. The anatomical location of this patient's lesion is reviewed in the context of alternative theories of the pathogenesis of NPE.

Cerebral cysticercosis with aqueductal obstruction

1980 ◽  
Vol 53 (2) ◽  
pp. 252-255 ◽  
Author(s):  
Tung Pui Poon ◽  
Edward J. Arida ◽  
Wolodymyr P. Tyschenko
Keyword(s):  
Intracranial Hypertension ◽  
Brain Stem ◽  
Normal Pressure Hydrocephalus ◽  
Signs And Symptoms ◽  
Normal Pressure ◽  
Content Type ◽  
Neurological Signs ◽  
Cerebral Cysticercosis ◽  
The Brain ◽  
Fine Print

✓ The authors report a case of cerebral cysticercosis which presented with generalized nonspecific neurological signs and symptoms attributed to acute aqueductal obstruction, with concomitant intracranial hypertension. These were characteristic intracranial calcifications along with angiographically demonstrated signs of hydrocephalus. Contrast encephalography clearly demonstrated aqueductal obstruction. Pathologically, the aqueductal obstruction was shown to be due to parasitic invasion of the brain stem with compression of the aqueduct. The presence of typical intracranial calcification in conjunction with either obstructive or normal-pressure hydrocephalus should alert the observer to the possibility of cerebral cysticercosis.

Odontoid compression of the brain stem in a patient with rheumatoid arthritis

1980 ◽  
Vol 53 (6) ◽  
pp. 841-845 ◽  
Author(s):  
Harold P. Smith ◽  
Venkata R. Challa ◽  
Eben Alexander
Keyword(s):  
Rheumatoid Arthritis ◽  
Brain Stem ◽  
Neurological Deficit ◽  
Neurological Symptoms ◽  
Direct Compression ◽  
Content Type ◽  
Vertical Subluxation ◽  
Progressive Neurological Deficit ◽  
The Brain ◽  
Fine Print

✓ Cervical spine involvement by rheumatoid arthritis is common; brain-stem compression secondary to vertical subluxation of the odontoid in patients with rheumatoid arthritis is rare. Vertical subluxation results from 1) destruction of the transverse atlantal, apical, and alar ligaments of the atlas and odontoid, and 2) bone resorption in the occipital condyles, lateral masses of the atlas, and basilar processes of the skull. Neurological symptoms result from direct compression of the brain stem or from ischemia secondary to compression of vertebral arteries, anterior spinal arteries, or small perforating arteries of the brain stem and spinal cord. A case is reported in which a slowly progressive neurological deficit developed in a woman with rheumatoid arthritis following a fall from a stretcher. Neurological symptoms represented direct compression of the medulla by the dens, a mechanism confirmed at operation and autopsy. Recognition of progressive neurological deficit is often difficult in patients with rheumatoid arthritis because of their inactivity and their atrophic and immobile joints, but is essential if appropriate decompressive or stabilizing procedures are to be done. In patients with vertical subluxation of the dens, the transoral approach with removal of the odontoid is recommended. Decompression should be extensive, including the fibrous capsule around the odontoid and overlying synovial tissue as well as the odontoid itself.

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