MRI changes during water loading in patients with polydipsia and intermittent hyponatremia.

OBJECTIVE: Patients with polydipsia and intermittent hyponatremia have greater ventricle-brain ratios (VBRs) than matched patients without polydipsia and intermittent hyponatremia and normal subjects. Unlike previous studies, this study controlled for the impact of water loading when examining the volume of intracranial structures. METHOD: Under controlled conditions, eight male schizophrenic patients with polydipsia and intermittent hyponatremia were first assigned to either normal fluid intake or oral water loading and then the alternative condition the following day. Magnetic resonance imaging (MRI) volumetric measurements were made with the use of a standardized protocol. RESULTS: During water loading, total VBR and lateral ventricle volume significantly decreased by 13.1% and 12.6%, respectively. A strong association between change in serum sodium concentration and change in VBR was noted across conditions. CONCLUSIONS: These findings indicate that 1) water loading does not account for the diminished brain volume observed in patients with polydipsia and intermittent hyponatremia in previous studies, and 2) hyponatremia can significantly alter brain morphology on MRI.

Deep cerebral venous thrombosis. Clinical, neuroradiological, and neuropsychological correlates.

Thrombosis of the deep cerebral venous system is usually fatal, and patients are frequently stuporous or comatose at presentation. This report describes serial radiological and neuropsychological observations in an 18-year-old woman who remained alert and survived this disorder. In association with diencephalic edema seen on computed tomographic scan, she demonstrated disorientation, abulia, attentional deficits, memory loss, and dyscalculia and had impaired IQ scores: the performance scores were worse than the verbal scores. Significant aphasia or sensory loss was absent. She recovered full intellectual capacity in the course of follow-up examinations, and the diencephalic edema seen on the computed tomographic scan resolved despite persistent thrombosis of the straight sinus demonstrable on follow-up digital angiography.

Multifocal intracranial MR abnormalities in neurofibromatosis.

MR imaging of four children with neurofibromatosis demonstrated areas of increased T2 signal involving widespread multifocal regions of basal ganglia and brainstem. Such abnormalities have not been previously reported. No corresponding CT abnormalities were present. These regions may represent hamartomatous or low-grade gliomatous change, and appear to be characteristic of neurofibromatosis in children.

Posterior fossa hemorrhage after supratentorial surgery.

PURPOSE: To evaluate the imaging findings, possible pathogenesis, and frequency of hemorrhage near the tentorial surface of the cerebellum after supratentorial surgery. METHODS: Over a 5-year period, 13 patients with posterior fossa hemorrhage after supratentorial surgery were identified with postoperative CT studies, which were obtained in all patients after craniotomy. Four of the 13 patients also had postoperative MR examinations. Preoperative and postoperative radiologic studies and medical records were reviewed. RESULTS: All hemorrhages were located along the superior aspect of the cerebellum transversely oriented along the cerebellar fossa and fissures. None of the patients had coagulopathy or radiologic evidence of posterior fossa tumor or vascular malformation. None of the hemorrhages had an appearance typical of hypertensive hemorrhage. Ten patients (77%) had lumbar drains placed before surgery and all had epidural drains placed at the conclusion of surgery. One patient had surgery for a meningioma, and 12 had surgery for aneurysms. The frequency of hemorrhage after aneurysmal surgery was 3.5%. No neurologic deficits developed referable to the cerebellum. CONCLUSIONS: Hemorrhage should be viewed as a potentially benign sequela of surgery rather than as an indication of hypertension, aneurysm, or previously unrecognized vascular malformation or neoplasm.

The value of CT in determining potential instability of simple wedge-compression fractures of the lumbar spine.

PURPOSE: To determine whether plain films alone are sufficient in the evaluation of stability of simple wedge-compression fractures of the lumbar spine. METHODS: Plain films and CT scans of 53 consecutive patients seen during a 2-year period with lumbar spine fractures were retrospectively reviewed. Six readers blinded to the CT diagnosis independently read each patient's plain films. Plain-film findings were scored on a five-point graded response scale using criteria proposed by Gehweiler and Daffner. In addition, a fracture was considered to be possibly unstable if there was involvement of more than one vertebral level or greater than 50% loss of anterior vertebral body height. CT findings represented the standard for comparison. CT scans were independently evaluated by three additional readers. Two-column involvement, middle-column involvement alone but with retropulsion, multiple-level involvement, or greater than 50% loss of vertebral height indicated potential instability. RESULTS: For 14 stable and 39 potentially unstable lumbar spine fractures, the pooled (mean) plain-film negative predictive value for detection of potentially unstable fractures was 0.62 (95% confidence interval, 0.53 to 0.70), with a sensitivity of 0.83 (95%, confidence interval; 0.78 to 0.87), and specificity of 0.80 (95% confidence interval, 0.70 to 0.87). CONCLUSION: Plain films are not adequate for determining stability of lumbar spine fractures.

Reversible empty sella in idiopathic intracranial hypertension: an indicator of successful therapy?

Idiopathic intracranial hypertension is commonly associated with an empty sella, caused by herniation of subarachnoid cerebrospinal fluid through an absent or patulous diaphragma sellae. We describe the findings in two patients who presented with headache, papilledema, and visual disturbances. Diagnosis of idiopathic intracranial hypertension was made on the basis of clinical symptoms and laboratory data. Initial imaging studies in each patient showed an empty sella. After treatment, one with acetazolamide and the other with lumboperitoneal shunting, the appearance of the sellar contents became normal.

Pleomorphic xanthoastrocytoma, a distinctive astroglial tumor: neuroradiologic and pathologic features.

PURPOSE: To analyze and discuss CT and MR features of pleomorphic xanthoastrocytoma (PXA) and present salient histopathologic features of this distinctive astroglial tumor. METHOD: CT, MR, and histopathologic studies on seven patients with the histologic diagnosis of PXA were reviewed retrospectively. RESULTS: All patients were in their first 3 decades of life when first diagnosed and demonstrated peripherally situated supratentorial tumors of varying size involving the superficial cortex and leptomeninges. Five of six cases examined with CT showed areas of mixed attenuation with four demonstrating well-demarcated enhancement. MR demonstrated low or mixed signal intensity on T1-weighted and high or mixed signal intensity on T2-weighted sequences. All five who received gadopentetate dimeglumine showed well-defined enhancement. Three showed cyst formation. Typical histologic features included marked cellular pleomorphism with giant cells, bizarre nuclei, variable cytoplasmic lipidization and positive immunoreactivity for glial fibrillary acidic protein. Necrosis and endothelial-pericytic cell proliferation were absent. CONCLUSION: PXA has a highly suggestive neuroradiologic and distinctive histopathologic appearance.

Persistent trigeminal artery with internal carotid artery occlusion.

A patient with a persistent trigeminal artery and occlusion of the internal carotid artery is presented. The development and protective hemodynamic significance of this persistent embryological anastomosis are briefly discussed.

Rathke's cleft cyst: computed tomographic and magnetic resonance imaging appearances.

A case of symptomatic Rathke's cleft cyst was studied preoperatively with x-ray computed tomographic and magnetic resonance imaging. A Rathke's cleft cyst may be differentiated from other cystic-appearing sellar masses.

Hydromyelia complicating Apert's syndrome: a case report.

A 7-year-old boy with Apert's syndrome and hydrocephalus presented with scoliosis and lower extremity weakness. Neuroradiological evaluation demonstrated bony abnormalities involving the foramen magnum and a markedly hydromyelic spinal cord. Clinical improvement followed posterior fossa decompression and a myelotomy on the caudal conus medullaris. A possible role of the craniofacial anomaly in the pathogenesis of the hydromyelia is discussed.

Spinal cord arteriovenous malformation in a neonate. Case report.

A 2-day-old neonate with a spinal cord arteriovenous malformation developed severe paraparesis. The abrupt neurological deterioration was not associated with hemorrhage or aneurysmal dilatation. Ischemic damage of the spinal cord is suggested as the cause of the clinical manifestation.

Treatment of cerebral vasospasm with intra-arterial papaverine.

Cerebral vasospasm continues to be the leading treatable cause of morbidity and mortality following aneurysmal subarachnoid hemorrhage. In this preliminary anecdotal series of 12 patients who were candidates for balloon angioplasty, vasospasm was treated instead with intra-arterial papaverine. Eight patients had marked angiographic reversal of the arterial narrowing following papaverine infusion, four of whom showed dramatic reversal of profound neurological deficits. Two patients deteriorated clinically 5 days after the initially successful papaverine infusions. In both, repeat angiography demonstrated severe recurrent vasospasm, which was partially reversed with a second intra-arterial papaverine treatment. Two patients developed focal neurological deficits during papaverine infusion, which resolved spontaneously over several hours after cessation of the intra-arterial infusion. Arterial narrowing in the posterior circulation and middle cerebral artery distribution appeared to be more responsive to papaverine infusion than was spasm in the anterior cerebral arteries. The infusion of 300 mg of papaverine over 1 hour seemed to be an adequate and safe dose to effect these angiographic and clinical improvements.

Progressive spasticity and scoliosis in children with myelomeningocele. Radiological investigation and surgical treatment.

Seventeen myelodysplastic patients with progressive extremity spasticity and scoliosis underwent radiological evaluation and surgical treatment. All but one were under 18 years of age at the time of surgical treatment. Duration of the clinical presentation ranged from 1 1/2 to 7 years. Metrizamide was instilled into the subarachnoid space in 12 patients, the lateral ventricle in two, and the hydromyelic cavity in three. Sequential computerized tomography scanning after intrathecal instillation of the contrast material clearly demonstrated hydromyelia in nine patients and compression of the brain stem in five. Posterior fossa decompression with plugging of the obex was performed in 12 patients, posterior fossa decompression alone in three, and ventriculoperitoneal (VP) shunting procedures in two. Of the 12 patients who underwent the obex plugging procedures, eight have shown partial or complete resolution of spasticity and an increase in motor strength with no significant postoperative complications. In contrast, posterior fossa decompression or VP shunting procedures alone have not led to a favorable neurological outcome. Hydromyelia may occur more commonly among myelodysplastic patients than previously recognized and may be treated most effectively by the obex plugging procedure.

Lumboperitoneal shunt combined with myelotomy for treatment of syringohydromyelia.

This study was undertaken to investigate whether a direct communication between the fourth ventricle and the syrinx exists in the majority of patients with syringohydromelia and whether intraspinal pressure plays a role in the pathogenesis of this disorder. A series of 13 patients with syringohydromyelia delineated by magnetic resonance (MR) imaging was reviewed, and the intracranial pressure (ICP) and lumbar spinal pressure (LSP) were recorded concomitantly in three patients. Lumboperitoneal shunting was performed in seven patients, six of whom also underwent myelotomy of the caudal spinal cord. Magnetic resonance imaging visualized a cerebrospinal fluid (CSF) channel connecting the fourth ventricle with the syrinx in only one of the 13 patients, and in the remaining 12 patients it revealed a long segment of the spinal cord free of syrinx below the fourth ventricle. This finding is in accordance with recent MR studies of syringohydromyelia. The concomitant recording of ICP and LSP in our patients who had myelomeningocele and Chiari II malformation showed findings contradicting the reports of Williams. Lumbar spinal pressure was equal to ICP under steady-state conditions, and was elevated by straining or crying more markedly than ICP. Craniospinal pressure dissociation with ICP greater than with LSP, as described by Williams, was not observed. Lumboperitoneal shunting concomitant with myelotomy and syringopleural shunting 1 month after myelotomy resulted in marked and sustained shrinkage of the syrinx and neurological improvement in four patients. It was concluded that the majority of patients with syringohydromyelia and Chiari malformation lack a direct communication connecting the fourth ventricle with the syrinx. The results suggest that CSF moves under pressure into the spinal cord, contributing to the formation and maintenance of the syrinx, and that LP shunting combined with myelotomy can effect shrinkage of the syrinx.

Moyamoya and other causes of stroke in patients with Down syndrome.

Twenty-seven new cases of stroke in Down syndrome are reported, two probands, 13 patients from review of institutional records, and 12 patients from a survey of child neurologists. Forty-one patients from previous reports are summarized. Most stroke episodes were related to congenital heart disease and infections. Seven cases were associated with angiographic abnormalities; there were three cases of unknown etiology and four cases of moyamoya. The understanding of moyamoya and other causes of stroke may be advanced by further study of stroke in Down syndrome patients.

Localization of intracranial lesions from CT scans.

Accurate localization of intracranial lesions from data derived from CT scans is necessary in the planning of surgery or radiotherapy. Several methods have been described previously. This report describes a simple method for localization which has many advantages over other methods without loss of accuracy.

Conjoined lumbosacral nerve roots. Diagnosis with metrizamide myelography.

The most common anomaly of the lumbosacral nerve roots consists of a composite root sleeve containing the roots for two spinal nerves. Before the advent of water-soluble myelography, this anomaly was rarely diagnosed except at operation. Metrizamide myelography readily demonstrates the anomaly because of improved filling of the root sleeves and greater definition of the nerve roots within the subarachnoid space. However, an underlying disk herniation may not be evident on the myelogram because of the unique anatomic configuration.

Intraventricular extension of a ruptured basilar artery aneurysm.

Penetration of the floor of the third ventricle by a saccular basilar bifurcation aneurysm accounted for a primary intraventricular hemorrhage in a 75-year-old women. This unusual relationship between the aneurysm and the third ventricle was clearly demonstrated by a computed tomographic (CT) scan only after the interface between the aneurysm and the ventricle was projected in a plane parallel to the ventricular floor. The CT scan interpretation was corroborated by an autopsy study. The principle of varying the plane of projection in order to obtain optimum delineation of the relationships of an aneurysm is well established in angiography, but has not previously been reported in the study of aneurysms by CT scan.