Shift Of Midline Structures Research Articles

Unilateral hydrocephalus: prenatal sonographic diagnosis.

We studied six cases of unilateral hydrocephalus detected prenatally to analyze the sonographic features of the abnormality and to determine the cause and clinical outcome. In all cases, third-trimester sonograms showed marked unilateral lateral ventriculomegaly (mean atrial width, 4.4 cm) and normal contralateral lateral, third, and fourth ventricles. Five of the six cases had marked thinning of the cortical mantle on the affected side and shift of midline structures to the contralateral side. The causes of unilateral hydrocephalus were agenesis or stenosis of the foramen of Monro in three cases, transient obstruction of the foramen in one fetus with an intraventricular hematoma, underlying brain dysplasia in one fetus with a variant of holoprosencephaly, and undetermined in one case. All six neonates had placement of a ventriculoperitoneal shunt catheter; four of these have had normal cognitive development at follow-up. The remaining two infants have moderate to severe developmental impairment. Unilateral hydrocephalus is a rare anomaly that can be recognized by prenatal sonography. Even though unilateral ventriculomegaly may be marked, early diagnosis and treatment may result in a favorable clinical outcome.

Sonography of Cerebral Infarction in Infancy

Six infants with cerebral infarcts were examined prospectively with real-time sonography to determine the sonographic characteristics of infarcts and their evolution. Patients9 ages ranged from 1 day to 7 months, and serial sonographic and/or CT scans were obtained over a period of 2 weeks to 14 months in the survivors. Among our patients the most characteristic sonographic findings of infarction were absence of gyral definition, absence of vascular pulsations, altered parenchymal echogenicity, and territorial distribution. Mass effect, reflected in ventricular size and shift of midline structures, may also be seen and largely parallels the extent of the infarction. Evolution of infarcts was seen sonographically as gradual return of arterial pulsations and concurrent development of cystic spaces. Sonography was found to be a valuable tool in the diagnosis of infarction in infancy and in monitoring its evolution, although CT was necessary for adequate initial evaluation in older infants.

Extradural hematoma: analysis of factors influencing the courses of 161 patients.

The clinical and computed tomographic (CT) findings in a series of 161 consecutive patients operated upon for postraumatic extradural hematoma are analyzed. Thirteen (8%) patients had delayed epidural hematoma formation. The overall mortality for the series was 12%, significantly lower than that observed during the prior "angiographic" period at the same unit (30%). Because all but 1 of the deaths occurred among the 66 patients unconscious at the time of operation (27% mortality in this subgroup), the authors sought differential factors between comatose and noncomatose patients at operation. There were no significant differences between these groups in age, sex, mechanism of injury, preoperative course of consciousness (lucid interval or not), or epidural hematoma location and shape. In contrast, significant differences were seen between the two subgroups in trauma-to-operation interval, hematoma volume, CT hematoma density (mixed low-high CT density vs. homogeneous hyperdensity), midline displacement, severity of associated intracranial lesions, and postoperative intracranial pressure (ICP). Patients comatose at operation usually evidenced a more rapid clinical deterioration (a shorter trauma-to-operation interval) and tended to have a large hematoma volume, a higher incidence of mixed CT density clot (hyperacute bleeding), more marked shift of midline structures, more severe associated lesions, and higher postoperative ICP levels.

Sonography of cerebral infarction in infancy.

Six infants with cerebral infarcts were examined prospectively with real-time sonography to determine the sonographic characteristics of infarcts and their evolution. Patients' ages ranged from 1 day to 7 months, and serial sonographic and/or CT scans were obtained over a period of 2 weeks to 14 months in the survivors. Among our patients the most characteristic sonographic findings of infarction were absence of gyral definition, absence of vascular pulsations, altered parenchymal echogenicity, and territorial distribution. Mass effect, reflected in ventricular size and shift of midline structures, may also be seen and largely parallels the extent of the infarction. Evolution of infarcts was seen sonographically as gradual return of arterial pulsations and concurrent development of cystic spaces. Sonography was found to be a valuable tool in the diagnosis of infarction in infancy and in monitoring its evolution, although CT was necessary for adequate initial evaluation in older infants.

Cerebral edema associated with craniectomy and arterial hypertension.

The present studies were performed to determine whether cerebral edema will develop as a consequence of arterial hypertension and/or craniectomy. Arterial hypertension was induced for 30 minutes by inflation of a balloon catheter situated in the descending aorta, and a parietal craniectomy was performed. The cerebral edema noticed was evaluated by macroscopic and microscopic observations, BBB permeability of HRP and Evans blue and water content. In addition, ICP was measured in the cisterna magna and ICPP by a catheter-tip transducer. In arterial hypertension or craniectomy alone, some small areas of Evans blue extravasation with increased water content were seen in the cortex, which corresponded to the occipito-parietal parts of the arterial boundary zones. In contrast, when arterial hypertension was combined with craniectomy, these lesions extended further into underlying white matter with increased water content. Forty-eight hours later, extensive brain edema with a shift of midline structures developed on the side of craniectomy which differed from that in arterial hypertension or craniectomy alone. It is suggested that some hydrostatic pressure gradients, particularly between blood vessel and surrounding extracellular space and among different areas within the brain parenchyma, may play an important role in the development of brain edema.

Permeability change of cerebral vessels in acute hypertension and external decompression

The role of hydrostatic factors, such as acute hypertension and decompressive craniectomy, which contribute to the permeability of cerebral vessels and to brain edema were evaluated. Adult mongrel cats were subjected to induced hypertension by means of inflation of a balloon catheter placed in the descending aorta immediately distal to the left sub-clavian artery. Craniectomy of 2×1.5 cm was done on the right front-parietal area. The animals were divided into four groups: 1) intact control group; 2) arterial hypertension group; 3) craniectomy group; 4) combined hypertension and craniectomy group. Evans blue and horseradish peroxidase were used as tracers to quantify the extent of damage to the blood-brain barrier. The water content of the regional cerebral tissues was determined by the dry-weight method. Induced hypertension produced multifocal cortical lesions staind by Evans blue. Craniectomy also resulted in similar multifocal cortical edema in both hemispheres, though more marked on the side of the craniectomy. These lesions were mainly located at the arterial boundary zones of major cerebral arteries and leakage of tracers ceased within 24 hours. No changes were observed in either brain water content or morphological findings 48 hours after insult. When a cat was subjected to both hypertension and craniectomy, these changes became markedly intensified and Evans blue, migrated further into the adjacent white matter. When the brain was examined 48 hours later, rather extensive hemispheric edema with midline structure shift was noted. The results suggested that edema of this type is sufficiently specific in its developmental pattern and is initiated by the hydrostatic pressure gradients between blood and tissue, and between areas with different tissue pressures.

INTRACRANIAL HYPERTENSION DURING SURGERY FOR SUPRATENTORIAL TUMOR

To test the hypothesis that preoperative head computed tomography scans could be used to predict the likelihood that a patient with a supratentorial brain tumor would develop intracranial hypertension during surgery before the cranium was opened, intraoperative intracranial pressure and blood pressure records of 60 patients undergoing craniotomy were compared with the appearance of their preoperative computed tomography scans. The scans were interpreted by a neuroradiologist who was unaware of the clinical events in each case. A positive correlation was found between the amount of preoperative brain edema observed surrounding tumors (on an arbitrary 0 to 3 + scale) and subsequent increases in intracranial pressure greater than base line values. No such correlation could be found with regard to tumor size, shift of midline structures, or effacement of the lateral ventricles. When preoperative brain edema seen on computed tomography scan was taken into consideration, increases in intracranial pressure during craniotomy also correlated with simultaneous increases in blood pressure. It is concluded that patients with large amounts of preoperative brain edema surrounding supratentorial tumors should be considered at risk for developing intraoperative intracranial hypertension and may benefit from preoperative insertion of an intracranial pressure monitor before general anesthesia is induced.

Intracranial Hypertension during Surgery for Supratentorial Tumor

To test the hypothesis that preoperative head computed tomography scans could be used to predict the likelihood that a patient with a supratentorial brain tumor would develop intracranial hypertension during surgery before the cranium was opened, intraoperative intracranial pressure and blood pressure records of 60 patients undergoing craniotomy were compared with the appearance of their preoperative computed tomography scans. The scans were interpreted by a neuroradiologist who was unaware of the clinical events in each case. A positive correlation was found between the amount of preoperative brain edema observed surrounding tumors (on an arbitrary 0 to 3 + scale) and subsequent increases in intracranial pressure greater than base line values. No such correlation could be found with regard to tumor size, shift of midline structures, or effacement of the lateral ventricles. When preoperative brain edema seen on computed tomography scan was taken into consideration, increases in intracranial pressure during craniotomy also correlated with simultaneous increases in blood pressure. It is concluded that patients with large amounts of preoperative brain edema surrounding supratentorial tumors should be considered at risk for developing intraoperative intracranial hypertension and may benefit from preoperative insertion of an intracranial pressure monitor before general anesthesia is induced.

Delta Waves in the EEGs of Patients With Intracerebral Hemorrhage

Localized polymorphic delta wave activity appears ipsilaterally in patients with intracerebral hematoma without a shift of midline structures, regardless of the location of hematoma. Appearance of delta wave slowing after thalamic bleeding is quite variable, however, and may produce localized slowing or unilateral diffuse polymorphic delta wave activity. Unilateral diffuse polymorphic delta wave activity is seen in patients with larger hematomas of 30 mL or more, which cause a shift of the midline structures. The shift of midline structures, including the hypothalamus and surrounding structures, is thought to be one of the main factors responsible for the production of unilateral responsible for the production of unilateral diffuse polymorphic delta wave slowing.

Congenital Porencephaly

Congenital porencephaly originates early in fet al development as a component of diffuse cerebral malformation. In infancy the patients have clinical manifestations of local or generalized cerebral disease. Convulsions, delaved growth and development and focal motor deficits are the most common clinical findings. Skull films, transillumination and brain scanning are useful methods of examination. Intracranial pneumography is the definitive means of diagbnosis. Roentgen studies in unilateral cases demonstrate characteristic changes. This pattern consists of ipsilateral calvarial enlargement and thinning, bilateral ventricular dilatation and contralateral shift of midline structures. Other anomalies of the cerebrum and meninges are often demonstrated on roentgen studies. The prognosis in these patients is guarded. Significant mental and motor retardation occurred in nearly all cases.

Dural sinus and cerebral venous thrombosis. Incidence in young women receiving oral contraceptives.

2 cases are presented of dural sinus and cerebral venous thrombosis in obese but healthy women who were using oral contraceptives. The first was 35-year-old with 5 children and a history of eclampsia and hypertension. She had used Enovid (norethynodrel and mestranol) intermittently for 2 years. She first noted right sided headache then gradually nausea vomiting diarrhea seizures weakness urinary incontinence. On hospitalization 5 days later an echoencephalogram showed shift of midline structures to the left a brain scan showed increased uptake on the right and an angiogram suggested an avascular mass. Craniotomy revealed an intracerbral hematoma and cortical vein thrombosis. She died 1 week later. The autopsy demonstrated thrombi in the superior sagittal sinus and a right frontal hematoma suggesting that the cortical vein thrombi propagated back leading to stasis infarction and hemorrhage. The second case was a 27-year-old mother of 3 who had been taking Ortho-Novum (norethindrone and mestranol) for 12 days. She had 2 days of severe headache then loss of dexterity and visual acuity. No venous pulsation could be seen in the optic fundi. Angiogram showed lack of filling of cortical veins. Spinal fluid had an opening pressure of 400 mm 320 red cells /ml and 80 mg protein/ml. On the fifth day she had Jacksonina seizures and on the eleventh day maximal shift of midline structures 8 cm to the left was measured. Except for thrombophlebitis of right leg and pulmonary embolism she gradually improved. Anticoagulant therapy is not advisable for patients with cerebral venous thrombosis after neurologic signs have developed for fear of evoking cerebral hemmorhage.

Truths and untruths concerning the angiographic findings in extracerebal haematomas.

A critical discussion of certain of the angiographic features of extracerebral haematomas is presented relating to: (1) the significance of an avascular space; (2) the significance of the shape of extracerebral haematomas; (3) the significance of the presence, degree or lack of shift of mid-line structures in association with an extracerebral haematoma; (4) the significance of “extravasation” of contrast medium from the middle meningeal artery.

Ultrasonic B-Scanning of the Brain

U LTRASOUND restricted to one-dimensional echo-ranging can provide little information other than the location of a plane reflecting surface. I ts value in neurological diagnosis, therefore, is limited virtually to detect ion of a shift of midline structures of the brain. ',6,s,15 The purpose of the present paper is to report early experiences with a two-dimensional ultrasonic visualization system, and to discuss the possible uses of this method for more precise demonst ra t ion of various norreal and abnormal intracranial structures. The physical principles underlying the use of ultrasound as a diagnostic technique have been presented in numerous reports} ,~,7,u,n Likewise, descriptions of the instrumentation of ultrasonic methods, including those used in this study, are readily available. Therefore, only certain fundamenta l details essential to unders tanding the clinical applications of this me thod will be repeated here. Sound consists of mechanical vibrations propagated in a medium. Sinee sound travels in a wave form, it is subject to many phenomena well known in optics, including reflection, refraction, absorpt ion and diffraction. When used for the purpose of delineating an object, the resolving power of sound, as in the ease of light, is limited to about 1 wave length. Because the velocity of sound in most soft tissues, including brain, is approximately 1500 m./sec. , frequencies well above audibility, i.e., ul t rasound, must be used to achieve useful resolution in these media. For example, wi th a f requency of 1.5 !VIc./sec., the wave length in soft tissue is about 1 ram. and under opt imal conditions the depth resolution,' i.e., the resolution in

Instrumental and technical notes. A graticule for use in neuroradiology.

To assess shift of mid-line structures shown on radiographs it is usually necessary for measurements to be taken. A graticule has been used in the Department of Neuroradiology for the last two years and has been found useful to demonstrate shifts. A prototype with ruled lines on cleared X-ray film base was first used. Later it was redrawn and photographic copies were made (Fig. 1).