RESUMO
The start-up of the first full scale Anammox reactor is complete. The reactor shows stable operation, even at loading rates of 10 kg N/m3.d. This performance is the result of the formation of Anammox granules, which have a high density and settling velocities exceeding 100 m/h. With this performance, the Anammox granular sludge technology has been proven on full scale.
Assuntos
Reatores Biológicos , Eliminação de Resíduos Líquidos/métodos , Bactérias Anaeróbias/metabolismo , Nitratos/metabolismo , Nitritos/metabolismo , Compostos de Amônio Quaternário/metabolismo , Esgotos , Poluentes Químicos da Água/metabolismoRESUMO
Pilot scale experiments were performed to evaluate the potential of nitrite type nitrification process with an airlift reactor and granular biomass. Initially, oxygen limitation was used as the main control parameter for accumulating nitrite in the effluent. After 30 d operation, the maximum nitrite conversion rate reached 2.5 kgNO2-N m(-3) d(-1), average diameter of the granule was 0.7 mm. Nitrite type reaction continued over 100 d, but nitrate formation increased after 150 d of operation. Once nitrate formation increased, oxygen limitation could not eliminate nitrite oxidising bacteria from granule. To overcome nitrate formation, laboratory scale batch experiments were conducted and it revealed a high concentration of inorganic carbon which had a significant effect on nitrite accumulation. Following this new concept, inorganic carbon was fed to the pilot scale reactor by changing pH adjustment reagent from NaOH to Na2CO3 and nitrite accumulation was recovered successfully without changing DO concentration. These results show that a high concentration of inorganic carbon is one of the control parameters for accumulating nitrite in biofilm nitrification system.
Assuntos
Reatores Biológicos/microbiologia , Bradyrhizobiaceae/crescimento & desenvolvimento , Carbonatos/química , Nitritos/análise , Aerobiose , Amônia/análise , Concentração de Íons de Hidrogênio , Nitratos/análise , Oxirredução , Tamanho da Partícula , Projetos PilotoRESUMO
The purpose of this study was to determine the angiogenic profile of human esophageal carcinomas. The expression of vascular endothelial growth factor (VEGF) was examined in 6 esophageal carcinoma cell lines and 119 human esophageal carcinoma tissues by Northern blot analysis and immunohistochemistry, respectively. Immunohistochemistry using antibodies against CD34 (endothelial cell specific) was carried out on archival specimens, and microvessels were quantitated by counting vessels in a x200 field in the most vascular area of the tumor. All of the cell lines constitutively expressed VEGF mRNA at various levels. A total of 71 of 119 (59.7%) tumors showed intense VEGF immunoreactivity in the cytoplasm of cancer cells. Vessel count was significantly higher in the VEGF-positive tumors than it was in the VEGF-negative tumors. VEGF expression correlated with the depth of tumor invasion, tumor stage, venous invasion, and lymphatic invasion. The survival rate of patients with high vessel density in the tumor was significantly worse than that of patients with low vessel density in the tumor. There was a tendency for poorer prognosis in the group with VEGF-positive tumors compared with that of the group with VEGF-negative tumors. Overall, these results suggest that VEGF is associated with tumor progression by stimulating angiogenesis in human esophageal carcinoma.
Assuntos
Carcinoma de Células Escamosas/irrigação sanguínea , Carcinoma de Células Escamosas/metabolismo , Fatores de Crescimento Endotelial/biossíntese , Neoplasias Esofágicas/irrigação sanguínea , Neoplasias Esofágicas/metabolismo , Linfocinas/biossíntese , Neovascularização Patológica/metabolismo , Northern Blotting , Progressão da Doença , Humanos , Prognóstico , Células Tumorais Cultivadas , Fator A de Crescimento do Endotélio Vascular , Fatores de Crescimento do Endotélio VascularRESUMO
Among primary lacrimal gland tumors, adenoid cystic carcinoma (ACC) is the most common malignant epithelial neoplasm; it is characterized by local intracranial invasion. A case with unusual dumbbell-type intracranial extension representing cavernous sinus syndrome is described. A 49-year-old woman was admitted to our hospital with right cavernous sinus syndrome. Computerized tomographic (CT) scans and magnetic resonance (MR) imaging demonstrated well-enhanced intraorbital and middle fossa tumors mimicking multifocal mass lesions. Operative findings revealed an ACC originating from the lacrimal gland and extending into the right cavernous sinus and middle fossa along the nerve sheath in the superior orbital fissure. Although MR image findings of intracranial ACC often resemble the image findings for meningiomas, intracranial ACC is very aggressive in comparison with meningioma. It is best treated surgically and aggressively.
Assuntos
Neoplasias Encefálicas/patologia , Carcinoma Adenoide Cístico/patologia , Aparelho Lacrimal/patologia , Encéfalo/patologia , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/cirurgia , Carcinoma Adenoide Cístico/diagnóstico por imagem , Carcinoma Adenoide Cístico/cirurgia , Seio Cavernoso/patologia , Feminino , Gadolínio , Humanos , Aparelho Lacrimal/diagnóstico por imagem , Aparelho Lacrimal/cirurgia , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios XRESUMO
The changes in the two consistent components of epidural pressure pulse wave (EDP-PW), P1 and P2 waves, and mean velocity of common carotid blood flow (CBFV) were studied in 21 patients with acute intracranial hypertension to investigate the origin of th the amplitude change in these components. The amplitudes of P2 wave increased progressively with the rise of EDP, but those of P1 wave remained nearly invariable at EDP of more than 20-30 mmHg which is incompatible with the changes in CBFV. Jugular vein compression caused in rapid rise of EDP and a proportionate increase in the magnitudes of both waves. Hyperventilation and mannitol administration caused a disproportionate reduction in the amplitudes of P2 wave with a fall of EDP. But mannitol at high EDP (more than 40 mmHg) caused a mild fall of EDP and some increase in the amplitudes of P2 wave. These results indicate that the variations in the amplitudes of P1 wave reflect the changes in vascular resistance of the large intracranial conductive arteries, while those of P2 wave result from the changes in the volume of the cerebral bulk. The increase in the amplitudes of P2 wave induced by mannitol at high EDP may suggest a defective autoregulation of the cerebral vessels.
Assuntos
Artérias Carótidas/fisiopatologia , Pressão Intracraniana , Pseudotumor Cerebral/fisiopatologia , Doença Aguda , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Espaço Epidural , Humanos , Pressão Intracraniana/efeitos dos fármacos , Manitol/farmacologia , Pessoa de Meia-IdadeRESUMO
The production and localization of platelet-activating factor (PAF) in the brain following focal brain injury were examined. Immunofluorescent staining was used to detect PAF in the rat brain with cold-induced local brain injury. After cold injury, immediate-early PAF staining was observed within the cold lesion followed later by immunoreactivity in the ipsilateral white matter. PAF immunoreactivity was also clearly seen both in cortical neurons adjacent to the cold lesion and in the ipsilateral hippocampus which showed delayed neuronal degeneration. The data suggest that PAF synthesis occurs in the neuronal cells in the perilesional area and hippocampus as well as within the cold lesion site during the early stages of cold-induced brain injury. PAF expression may contribute to the onset and progression of further brain damage, such as delayed axotomy and delayed neuronal loss.
Assuntos
Lesões Encefálicas/metabolismo , Encéfalo/metabolismo , Neurônios/metabolismo , Fator de Ativação de Plaquetas/metabolismo , Animais , Encéfalo/patologia , Encéfalo/fisiopatologia , Edema Encefálico/metabolismo , Edema Encefálico/patologia , Edema Encefálico/fisiopatologia , Lesões Encefálicas/patologia , Lesões Encefálicas/fisiopatologia , Temperatura Baixa/efeitos adversos , Imunofluorescência , Masculino , Degeneração Neural/metabolismo , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Fibras Nervosas Mielinizadas/metabolismo , Fibras Nervosas Mielinizadas/patologia , Neurônios/patologia , Lobo Parietal/metabolismo , Lobo Parietal/patologia , Lobo Parietal/fisiopatologia , Ratos , Ratos WistarRESUMO
The neuroprotective action and effect of hypothermia on the neurochemical system is not well understood. The present study was performed using six patients with GCS scores of 5 or less to clarify the relationship between monitored brain temperature, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and oxygen saturation of the jugular venous blood (SjO2). Changes in concentration of excitatory amino acids, glutamate (GLU) and aspartate (ASP), and NO2 were studied using intracerebral microdialysis as well as in jugular venous blood and cerebrospinal fluid (CSF). Changes in brain temperature, CPP and SjO2 resulting from hypothermia and brain death associated with markedly higher concentrations of and fluctuations in the concentrations of GLU, ASP and NO2 were observed in the dialysate than in the jugular venous blood or CSF. Hypothermic treatment significantly reduces excitatory amino acid and NO2 concentrations, a finding which was associated with an improvement in CPP and SjO2. Measurement of GLU and ASP using intracerebral microdialysis is a clinically useful method for clarifying abnormal neurochemical events associated with severe head injury and for evaluating the effects of hypothermia.
Assuntos
Ácido Aspártico/metabolismo , Encéfalo/metabolismo , Traumatismos Craniocerebrais/metabolismo , Ácido Glutâmico/metabolismo , Hipotermia Induzida , Óxido Nítrico/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Temperatura Corporal/fisiologia , Traumatismos Craniocerebrais/terapia , Feminino , Humanos , Hipotermia Induzida/métodos , Pressão Intracraniana/fisiologia , Masculino , Microdiálise/métodos , Pessoa de Meia-IdadeRESUMO
To ascertain the critical thresholds of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) for cerebral circulation and brain function, the extra- and intracranial haemodynamics and electrical brain responses were evaluated noninvasively with Doppler ultrasonography and multimodality evoked potentials (MEP's) in 50 patients with severe head injury. Both extra- and intracranial blood flow velocities changed monotonically depending on the changes in ICP and CPP. They were decreased when ICP increased to 20-30 mmHg and when CPP decreased to 40-50 mmHg. The changes in elasticity index of the pulse wave of the common carotid artery was proportional to those of blood flow velocities. The frequency and degree of abnormalities of MEP's were proportionally increased with the rise of ICP and reduction of CPP. When ICP increased to higher than 31 mmHg, MEP's were classified as moderately or severely abnormal in more than 76% of the recordings. These results indicate that noninvasive study by use of Doppler ultrasonography and MEP's can provide valuable information on critical brain ischaemia and brain dysfunction in patients with acute intracranial hypertension.
Assuntos
Lesões Encefálicas/fisiopatologia , Circulação Cerebrovascular , Pressão Intracraniana , Ultrassonografia , Adolescente , Adulto , Idoso , Velocidade do Fluxo Sanguíneo , Lesões Encefálicas/diagnóstico , Humanos , Pessoa de Meia-IdadeRESUMO
Gordonia amarae is the cause of foaming activated sludge. In this study, the mechanism of foam formation by G. amarae SC1 was investigated. A liquid culture of SC1 cells generated a stable foam when shaken reciprocally. This foam formation was dependent on the presence of both bacterial cells and culture supernatant. A high-molecular-weight fraction (Mw>10000) of the supernatant was capable of emulsifying n-hexadecane in addition to exhibiting foaming activity, indicating that it contains a surface-active substance(s). The bacterial cells showed a high affinity to hexadecane. This hydrophobic cell surface property might be involved in the attachment of cells to air bubbles to generate a stable foam. The results demonstrated the participation of cells and the extracellular biosurfactant in the formation and stabilization of foam in G. amarae SC1 culture.
RESUMO
BACKGROUND: A new surgical treatment of middle fossa arachnoid cyst is reported. The benefit of our surgical procedure is to maintain the physiologic pathway of the cerebrospinal fluid (CSF) without a shunting procedure. METHODS: Following a small frontotemporal craniotomy, a linear incision in the outer wall of the cyst is made. The basal subarachnoid cisterns and distal sylvian cisterns are widely opened microsurgically. The outer wall of the cyst is then closed to prevent CSF leakage (arachnoidplasty). RESULTS: We have experienced six patients who underwent this new surgical treatment. All their cysts showed nor or delayed influx of the contrast medium on preoperative computed tomography cisternogram. A favorable outcome was attained in the long-term follow-up without any complications. CONCLUSIONS: The present technique was designed to secure physiologic CSF circulation and to avoid the use of a shunting system. A total of six patients treated with our new technique have been followed-up 6 years, and a good clinical outcome has been observed in all of them without complications.
Assuntos
Cistos Aracnóideos/cirurgia , Adulto , Cistos Aracnóideos/diagnóstico por imagem , Cistos Aracnóideos/patologia , Cistos Aracnóideos/fisiopatologia , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Tomografia Computadorizada por Raios XRESUMO
A case of pituitary apoplexy is reported in a 14-year-old girl who presented with headaches and progressive visual disturbance. Magnetic resonance imaging demonstrated subacute hemorrhage into a pituitary adenoma. Transsphenoidal removal of the tumor was performed successfully. Pituitary apoplexy in children is rare. Thus we will discuss the clinical features and neuroradiological findings.
Assuntos
Apoplexia Hipofisária/diagnóstico , Adolescente , Diagnóstico Diferencial , Feminino , Humanos , Imageamento por Ressonância Magnética , Apoplexia Hipofisária/complicaçõesRESUMO
This paper reports the use of cranioplasty using segments of split lateral skull plate to correct large skull defects (larger than 8 x 8 cm). The subjects consisted of 10 patients with head trauma who had undergone decompression surgery, and two patients who had undergone tumour resection. Bone grafts were obtained by cutting approximately 2 cm wide strips from the lateral skull plate using a bone saw that was inserted from a free margin of the bone defects. By cutting strips laterally from the bone defect, the necessary amount of split lateral skull plate can be obtained without performing craniotomy. The pieces of split lateral skull plate are then fixed to the defect using wire or titanium mini-plates. At this point, the selection of bone grafts that match the curvature of the dura mater is important, so that no dead spaces are created between the dura mater and the bone grafts. Infection was not detected in any of the 12 patients, and all bone grafts took completely. One of the 12 patients suffered from a pathological fracture and bone resorption 6 months after surgery. The fracture occurred because the use of basket-shaped reconstruction plates resulted in large spaces between the plate segments, and in addition the intracranial pressure was kept low by a V-P shunt, thus rendering the patient more vulnerable to atmospheric pressure.
Assuntos
Procedimentos de Cirurgia Plástica/métodos , Crânio/cirurgia , Adolescente , Adulto , Criança , Feminino , Hematoma Subdural/cirurgia , Humanos , Masculino , Neoplasias Meníngeas/cirurgia , Meningioma/cirurgia , Pessoa de Meia-Idade , Crânio/lesões , Fraturas Cranianas/cirurgiaRESUMO
MRI was performed on 120 patients who sustained closed head injury of varying severity. Patients ranged in age from 4 to 87 years (average, 32 years). All patients had an initial MRI within 28 days (median 12 days) of injury. MRI disclosed areas of abnormal signals in the corpus callosum of 21 (18%) of the 120 patients; 1 (2%) of the 44 patients who sustained mild injuries (GCS > or = 13), 3 (10%) of the 31 moderate injuries (GCS 9-12), and 17 (38%) of the 45 severe injuries (GCS < or = 8) (p < 0.0001). All but 2 of the 21 patients with corpus callosum lesions had other parenchymal lesions that were visualized by MRI. Of these 21 patients, MRI was repeated in 19. In 13 of the 19 patients, repeat MRI scans at 25 to 42 days after injury showed the disappearance of lesions that had on the first MRI shown a high signal on T2-weighted and FLAIR images and a normal signal on T1-weighted images. The MRI findings and time source of the disappearance of the corpus callosum lesions mirrored those of paracontusional edema in the subcortical white matter. Patients in whom the corpus callosum lesion disappeared had a better outcome than those in whom the lesion remained (good recovery/moderate disability; 92% vs 63%). The present MRI results suggest that some lesions in the corpus callosum following closed head injury are reversible, thus resembling edema that may be produced by a relatively mild shear strain force to the corpus callosum.
Assuntos
Edema Encefálico/etiologia , Corpo Caloso/lesões , Traumatismos Cranianos Fechados/complicações , Imageamento por Ressonância Magnética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Edema Encefálico/diagnóstico , Criança , Pré-Escolar , Corpo Caloso/patologia , Feminino , Traumatismos Cranianos Fechados/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do TratamentoRESUMO
We report a case of spontaneous epidural hematoma secondary to dural metastasis of an undifferentiated ovarian carcinoma. The hemorrhage occurred 2 days after oophorectomy. The hematoma was evacuated, and histological examination of the galea and dura mater revealed metastatic ovarian carcinoma. The absence of other pathology in the vicinity of the hematoma indicates that the hemorrhage was caused by the dural metastasis. Although subdural hematoma secondary to dural metastasis has been reported, this is believed to be the first reported case of epidural hematoma attributable to dural metastasis.
Assuntos
Neoplasias Encefálicas/secundário , Carcinoma/secundário , Hematoma Epidural Craniano/etiologia , Neoplasias Ovarianas , Adulto , Neoplasias Encefálicas/patologia , Carcinoma/patologia , Feminino , Hematoma Epidural Craniano/diagnóstico por imagem , Humanos , Metástase Neoplásica , RadiografiaRESUMO
A rare case of multiple traumatic aneurysms, arising from the distal anterior cerebral artery (ACA), associated with a diffuse axonal injury is presented. An 18-year-old male sustained a frontal impact injury in a traffic accident on February 19, 1988. He immediately lost consciousness and was transported to a local hospital where his Glasgow Coma Scale score was 6. A computed tomographic scan showed a traumatic subarachnoid hemorrhage extending from the corpus callosum to the left parietal lobe. With conservative treatment, he gradually regained consciousness and was referred to our hospital 12 days later. Skull x-rays revealed no fracture. A right common carotid angiogram revealed multiple aneurysmal dilatations on the right distal ACA. A left frontoparietal craniotomy was then performed to determine the nature of the aneurysmal dilatation, and to evacuate the intracerebral hematoma because his right hemiparesis persisted. Two aneurysmal dilatations on the distal ACA were tightly surrounded by clots and a hematoma extended from the corpus callosum to the parietal lobe. The ACA was trapped proximal and distal to the aneurysmal dilatations. The postoperative course was uneventful.
Assuntos
Lesões Encefálicas/complicações , Aneurisma Intracraniano/etiologia , Adolescente , Axônios/patologia , Lesões Encefálicas/patologia , Humanos , Masculino , Hemorragia Subaracnóidea/etiologiaRESUMO
A 43-year-old male presented with swelling involving the right eye. T1-weighted magnetic resonance imaging demonstrated a round tumor in the lateral region of the right orbit, which was isointense relative to the cerebral gray matter and homogeneously enhanced by gadolinium-diethylenetriaminepenta-acetic acid with a flow-void signal area in the mass. The tumor was totally resected through the transcranial and fronto-orbitotemporal approach after embolization of feeding arteries arising from the external carotid artery. The histological findings were characteristic of hemangiopericytoma. No radiation therapy was administered. The transcranial and fronto-orbitotemporal approach provides a wide operative field with excellent exposure of the highly vascular orbital tumor.
Assuntos
Hemangiopericitoma/cirurgia , Neoplasias Orbitárias/cirurgia , Angiografia Cerebral , Terapia Combinada , Craniotomia , Embolização Terapêutica , Hemangiopericitoma/diagnóstico , Hemangiopericitoma/patologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Órbita/irrigação sanguínea , Órbita/patologia , Órbita/cirurgia , Neoplasias Orbitárias/diagnóstico , Neoplasias Orbitárias/patologiaRESUMO
The obstructive tissue in eight malfunctioning ventricular catheters without infection was studied using scanning and transmission electron microscopy. Shunt obstruction was due to debris from ventricular structures such as the choroid plexus and ependymal tissue. There was a preponderance of collagen fibers, and many fibroblasts were present within these tissues. The cytoplasm of the fibroblasts contained extended endoplasmic reticulum. The tissues filled the lumen of the catheters in radially arranged layers. Peeling the silicone was seen on the surface of the ventricular catheters but was not present in normal silicone catheters. Finger-like microvilli were observed on the free surface of the tissue. Many vessels were seen in the transverse section of the tissue. Activated fibroblasts and vascularization may be important in tissue growth in ventricular catheters.
Assuntos
Ventrículos Cerebrais/patologia , Hidrocefalia/cirurgia , Derivação Ventriculoperitoneal/instrumentação , Adolescente , Adulto , Criança , Análise de Falha de Equipamento , Feminino , Humanos , Hidrocefalia/patologia , Processamento de Imagem Assistida por Computador , Masculino , Microscopia Eletrônica , Microscopia Eletrônica de Varredura , Propriedades de SuperfícieRESUMO
The importance of diffuse axonal injury (DAI) and early intracranial sequelae was studied in 107 patients with diffuse and focal brain injuries. Comprehensive neuropathological study was also undertaken in 24 fatal patients. The mortality rate was clearly the highest in traumatic subarachnoid hemorrhage, followed by acute subdural hematoma, cerebral contusion with delayed hematoma formation, traumatic intracerebral hematoma, diffuse cerebral swelling, DAI with classical features, and finally nearly normal on computed tomographic scans. The mean flow velocities in the middle cerebral artery recorded by transcranial Doppler ultrasound were variable in diffuse brain injury, but commonly decreased on the hematoma side depending on increased intracranial pressure and decreased cerebral perfusion pressure in focal brain injury. Deep-seated hemorrhagic lesions did not expand in diffuse brain injury, but sizable hematoma developed within 24 hours in focal brain injury. The platelet count was significantly lower in patients with poor outcomes in focal brain injury. Histological evidence of classical DAI was found in eight (50%) of 16 cases with focal brain injury. DAI of varying severity is the common subjacent lesion in patients with severe head injury, but the final outcome varies greatly with different lesion types.
Assuntos
Axônios/ultraestrutura , Concussão Encefálica/etiologia , Hemorragia Cerebral/etiologia , Traumatismos Craniocerebrais/patologia , Hematoma/etiologia , Traumatismos Craniocerebrais/complicações , Traumatismos Craniocerebrais/fisiopatologia , Escala de Coma de Glasgow , HumanosRESUMO
A 69-year-old man presented with progressive cervical myelopathy due to vascular compression of the upper cervical spinal cord. Vertebral angiography and magnetic resonance imaging revealed that the elongated bilateral vertebral arteries (VAs) had compressed the spinal cord at the C-2 level. The spinal cord was surgically decompressed laterally by retracting the VAs with Gore-Tex tape and anchoring them to the dura. The patient's symptoms improved postoperatively. Decompression and anchoring of the causative vessels is recommended due to the large size of the VAs.
Assuntos
Compressão da Medula Espinal/etiologia , Artéria Vertebral , Idoso , Vértebras Cervicais , Humanos , Imageamento por Ressonância Magnética , Masculino , Compressão da Medula Espinal/diagnóstico , Tomografia Computadorizada por Raios X , Doenças Vasculares/complicações , Doenças Vasculares/diagnóstico , Doenças Vasculares/cirurgia , Artéria Vertebral/cirurgiaRESUMO
The clinical significance of traumatic subarachnoid hemorrhage (TSAH) was studied in 20 head-injured patients. They were classified into mild (9) and severe (11) groups by their initial Glasgow Coma Scale (GCS) scores. TSAH detected by computed tomography was localized in the Sylvian fissure in four of the nine mild group patients, but was also found in other basal subarachnoid cisterns in the other five. Except for one patient who developed delayed vasospasm and communicating hydrocephalus, all had favorable outcomes in this group. Massive TSAH was noted in the basal subarachnoid cisterns in 10 severe group patients and only one had a good outcome. Delayed intracerebral hematoma in the frontal or temporal lobe in the vicinity of the Sylvian fissure was found in two mild and two severe group patients with TSAH in the Sylvian fissures. Traumatic parenchymal lesions in the brainstem were minimal in one of the two autopsied patients and no evidence of diffuse axonal injury was found in both cases. Thus, TSAH in the Sylvian fissure is suggestive of focal brain contusion around the fissures. Massive TSAH in the basal subarachnoid cisterns is not necessarily associated with severe parenchymal injury of the brainstem.