Neuroradiology diagnostic errors at a tertiary academic centre: effect of participation in tumour boards and physician experience.

AIM: To quantify and correlate the diagnostic error rates in radiological interpretation with the experience of the attending neuroradiologist at a tertiary academic medical centre. MATERIALS AND METHODS: The institution's Neuroradiology Quality Assurance Database of diagnostic errors was searched for misses from 2014-2020. Attendance at Head and Neck (H&N), Brain, and Paediatric Neuroradiology (PN) tumour boards (TB) as the presenting radiologist was recorded. Number of post-fellowship years of clinical practice (CPY) and frequency of TB attendance were considered separate metrics of a radiologist's experience. Radiological errors were categorised as Total, H&N, Skull Base (SKB), Brain, or PN diagnostic errors. Diagnostic error rates per attending neuroradiologist within each category were correlated with the frequency of TB participation and CPY using Spearman's rank correlation coefficients. RESULTS: A total 607 examinations contained a diagnostic error. Spearman's rank correlation coefficients between Total TB participation and Total, H&N, SKB, Brain error rates were: -0.89 (p=0.0002); -0.81 (p=0.002); -0.66 (p=0.03); -0.82 (p=0.002); respectively. Spearman's rank correlation coefficients between CPY and Total, H&N, SKB, Brain and PN error rates were: 0.05 (p=0.88); 0.08 (p=0.82); 0.28 (p=0.41); -0.10 (p=0.77); -0.16 (p=0.63), respectively. Spearman's rank correlation coefficients between H&N TB and H&N, SKB error rates; and between Brain TB attendance and Brain error rates were statistically significant (p<0.05). CONCLUSION: The present study shows a strong correlation between high TB participation rates and low diagnostic error rates. The number of years in practice did not appear to influence error rate.

Analysis of misses in imaging of head and neck pathology by attending neuroradiologists at a single tertiary academic medical centre.

AIM: To analyse errors in head and neck (H&N) pathology made by attending neuroradiologists at a single tertiary-care centre. MATERIALS AND METHODS: A neuroradiology quality assurance (QA) database of radiological errors was searched for attending physician errors in H&N pathology from 2014-2020. Data were limited to computed tomography (CT) and magnetic resonance imaging (MRI) reports. Data were collected on missed pathologies and study types. Misses were grouped into three categories: central neck (thyroid gland, aerodigestive tract), lateral neck (salivary glands, lymph nodes, soft tissues), and face/orbits (orbits, sinuses, masticator space). RESULTS: During the study period, a total of 283,248 CT and MRI neuroradiology examinations were interpreted (all indications). Seventy-four H&N misses were identified comprising 85.1% perceptual and 14.9% interpretive errors. The distribution of errors was face/orbits (37.8%), central neck (36.5%), and lateral neck (25.7%). Clinically significant errors were found most commonly in the aerodigestive tract (21%), orbits (17.7%), masticator space, and parotid glands (14.5% each). The majority (67.6%) of the misses were detected on examinations that were not performed for a primary H&N indication; MRI brain was the most common examination (27%). Clearly malignant or potentially malignant masses accounted for 48.6% of all misses. CONCLUSION: The majority of H&N misses were perceptual and were detected on examinations not performed for a H&N indication. Clearly malignant or potentially malignant masses represented half of all misses.

Stroke due to vertebral artery injury.

Minimal neck injury produced vertebral artery damage in two women and three men, 20 to 57 years of age. Serious neurologic deterioration occurred in two patients when positioned for roentgenographic procedures. Dissection or thrombosis of one or both vertebral arteries while in the transverse foramina occurred in three, one at the site of an osteophyte. The arteriogram of one patient showed a traumatic aneurysm at C-7, and a second patient had segmental arterial stenosis with bilateral traumatic aneurysms at C-5. The location of the arterial injury is not restricted to the occipitoatlantoaxial level but includes the course through the transverse foramina. The use of anticoagulation appears to be important in the immediate management of this process.

Xenon-enhanced computed tomography in brain death.

The absence of cerebral blood flow is a valuable adjunct confirming clinical criteria of brain death. However, current methods to confirm absent cerebral blood flow have problems that limit their clinical use. We reviewed cerebral blood flow data obtained with xenon-enhanced computed tomography in nine patients who were being evaluated for brain death. In eight patients who met clinical criteria for brain death, mean cerebral blood flow was 1.6 +/- 2.0 mL X 100 g X min. This value was within the range of error inherent in the method, and therefore represented absent flow. In a patient with persistent respiratory efforts, flow values compatible with absent flow were obtained in the supratentorial compartment, while mean flows as high as 24 mL X 100 g X min were measured in selected regions of interest in the infratentorial compartment, correlating with the clinical evidence of residual function of the brain stem. Xenon-enhanced computed tomography may be a useful test to confirm the absence of cerebral blood flow in patients being evaluated for brain death.

The alien hand syndrome. Clinical and postmortem findings.

Two patients had automatonlike movements of their left hands and arms (alien hand syndrome) following damage to the brain. Autopsy findings in one patient demonstrated gunshot wound damage to the medial frontal white matter bilaterally, as well as the corpus callosum, right basal ganglia, internal capsule, and thalamus. The other patient had a ruptured anterior communicating aneurysm, with subsequent resection of the right frontal gyrus rectus. We postulate that this syndrome is due to the combination of a partial callosectomy and mesial frontal lesions.

Superficial temporal to middle cerebral artery anastomosis. Clinical outcome in patients with ischemia of infarction in internal carotid artery distribution.

The clinical outcome of our first 40 patients (six with transient ischemic attacks, 22 with mild ischemic infarctions, and 12 with moderate ischemic infarctions) treated with a superficial temporal artery-middle cerebral artery anastomosis was analyzed. All cerebral ischemias or infarctions occurred in the internal carotid artery distribution. An independent neurologist observer recorded the patients preoperative and postoperative medical and neurological histories and objective neurological findings. There was no operative mortality. During the period of observation (up to 36 months), four patients died of probable myocardial infarction. No patient suffered from recurrent cerebral infarction. Three patients experienced a single ischemic event postoperatively. Neurological deficits were either unchanged (21 patients) or improved (19 patients). Postoperative angiograms showed patency in 97% of the anastomoses.

Childhood oligodendrogliomas presenting with seizures and low-density lesions on computed tomography.

Three children with cerebral oligodendrogliomas causing partial complex or generalized seizures presented with completely normal neurologic examinations. CT showed low-density, nonenhancing surface lesions. Although these CT features are usually associated with infarcts or cysts, neoplasm was suspected because of irregularity of the margins and erosion of the adjacent inner table of the skull. Oligodendrogliomas often enlarge slowly and may cause seizures years before they produce focal neurologic signs. CT of all children with seizures not responsive to anticonvulsant medication and focal clinical or EEG abnormalities will hasten diagnosis of slowly growing intracranial mass lesions.

Advances in the genetics of cerebrovascular disease and stroke.

MEDLINE searches identified epidemiologic, experimental, and clinical studies on the genetics of cerebrovascular disease and stroke, including the following topics: genetic epidemiology of stroke; genetics of systemic disorders that cause ischemic stroke, including coagulation disorders, connective tissue disorders, vasculopathies, metabolic disorders, and disorders of unknown etiology; and genetics of systemic disorders that cause hemorrhagic stroke. Recent discoveries in stroke genetics involve the genetic basis of monogenic disorders such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy and sickle cell disease. Reproducing similar advances in other forms of cerebrovascular disease and stroke will be more difficult because their inheritance is complex, multigenic, and heterogeneous. However, the future is promising with the application of molecular genetic approaches such as linkage analysis, allele-sharing methods, association studies, and polygenic analysis of experimental crosses as well as the transmission/disequilibrium test--a statistical method for detection of linkage between a marker and a disease-susceptibility locus.

Intracerebral hemorrhage in the full-term neonatal infant.

Supratentorial intracerebral hemorrhage was diagnosed in 18 full-term neonates, including six with primarily intraparenchymal hemorrhage and 12 with primarily intraventricular hemorrhage. Precipitating or associated factors were hypoxic-ischemic injury in five patients, polycythemia in two, and cranial birth trauma in two. Nine other infants had no identifiable medical risk events. The pathogenesis of intraparenchymal hemorrhage was probably related to hemorrhagic infarction, but the pathogenesis of intraventricular hemorrhage was often unknown. All 17 survivors returned for neurologic and developmental examinations between 1 and 7 years of age. Follow-up assessments were normal in nine children and abnormal in eight. Two had perceptual difficulties, three had moderate-to-severe cognitive deficiencies (two of the three had hemiplegia), and three had severe mental and neurologic handicaps. Eight of nine children with known or suspected hypoxic-ischemic or traumatic insults suffered moderate-to-severe disabilities whereas eight of nine children with no known precipitating cause for their hemorrhage developed normally.

Long-term outcome of Hurler syndrome following bone marrow transplantation.

Previous reports suggested a therapeutic response of lysosomal storage diseases such as Hurler syndrome following bone marrow transplantation. However, a clearer understanding of outcome has awaited long-term follow-up. We evaluated prospectively 11 consecutive patients with Hurler syndrome receiving marrow from an HLA-identical sib donor between September 1983-October 1988. Follow-up evaluations included assessment of donor engraftment by restriction fragment polymorphism analysis, determination of leukocyte alpha-L-iduronidase level, measurement of lumbar cerebrospinal fluid (CSF) pressure, computerized tomography (CT) of the brain, and psychometric testing. In this series there was a survival rate of 9/11 (82%) with all survivors showing complete (7 patients) or partial (2 patients) donor engraftment. Prospective longitudinal evaluation of the 9 surviving children, now 3.8-8.9 years posttransplantation (median 5.5) demonstrated persistence of previously deficient leukocyte alpha-L-iduronidase at levels reflecting the donor genotype and degree of donor engraftment. Urinary glycosaminoglycan excretion declined to near-normal within 5 months of donor engraftment. Prior to treatment, 7 of 8 children studied were found to have occult intracranial hypertension (lumbar CSF pressure > 20 cm CSF); however, all surviving children attained normal or near-normal pressure within 18 months of donor engraftment. Longterm follow-up CT imaging of the brain did not show progressive volume loss (cerebral atrophy) after donor engraftment. Of 9 survivors, 4 children having a developmental quotient (DQ, Mental Development Index on Bayley Scales of Infant Development) above 80 prior to transplantation subsequently maintained IQ scores above this level. However, 5 patients with lower pretransplant DQ scores now have significant cognitive deficits and attention deficit hyperactivity disorder. Progressive brain damage resulting from communicating hydrocephalus may be prevented by successful engraftment. Early transplantation of children with Hurler syndrome who have normal intelligence is likely to have the clearest benefit because long-term intellectual outcome will be limited by brain damage which has occurred prior to treatment.

The use of nonionic contrast agents in neuroangiography. A review of the literature and recommendations for clinical use.

RATIONALE AND OBJECTIVES: Several large studies have demonstrated the improved safety record of nonionic versus ionic contrast agents for intravenous administration. However, nonionic agents are much more expensive than ionic agents. The author addresses whether, given this large cost differential, nonionic contrast agents should always be used in neuroangiography (cerebral and spinal cord angiography and intravascular neurointerventional procedures). The answer could come from a closer examination of the effects of contrast agents on the brain. METHODS: There have been a number of animal experiments and clinical trials performed using a variety of available intravascular contrast agents. In an attempt to arrive at some reasonable conclusions regarding the use of contrast agents today, the author reviews several of these studies. In the human studies, three areas were analyzed: 1) cerebral angiography, 2) spinal cord angiography, and 3) intravascular neurointervention. The author explains why demonstrating the effect of a contrast agent on the brain or spinal cord in the clinical setting is more difficult than studying the effect of this agent on the liver, heart, or kidney. For example, obtaining objective measurements of altered cerebral physiology following intravascular injection of a contrast agent may itself alter the physiology. In lieu of objective measurements, investigators must rely on apparent changes in behavior, mentation, or the production of a focal neurologic deficit. However, it is extremely difficult, if not impossible, to separate the effect of the contrast agent from the effects of the arteriographic procedure, or from the disease process being evaluated. RESULTS: The neuronal environment is protected by the blood-brain barrier. A number of animal experiments have demonstrated that nonionic agents produce breakage of the blood-brain barrier less frequently than do ionic agents. In these studies, nonionic agents also produced fewer neurologic effects than did ionic agents. The human studies showed no statistically significant differences in neurologic effects when ionic and nonionic agents were compared. Cerebral: minor changes in heart rate were more common with ionic than with nonionic agents; there were no significant electroencephalogram changes in any of the patients studied. Spinal cord: the effects of intravascular injections of contrast material into the spinal cord of experimental animals have been rarely evaluated; direct comparisons of contrast agents in human spinal cord angiography have not been performed. Neurointervention: there have been no comparative studies of different contrast agents used during intravascular neurointerventional procedures in humans. CONCLUSIONS: Extensive animal data demonstrate that nonionic contrast agents are safer than ionic for cerebral angiography. Animals in the cited studies show less blood-brain barrier disruption, fewer direct neuronal effects, and fewer neurobehavioral deficits. However, the overwhelming conclusion from the human studies is that, while there is evidence in the experimental animal that nonionic agents produce fewer neurologic effects than do ionic agents, no study to date has been able to translate these findings into an apparent clinical difference in humans, mainly because it's so difficult to detect and measure neurologic changes in human trials. In addition, differences in neurologic effects between contrast agents used in human studies may be relatively small. Thus, one must make an educated guess as to the appropriate use of contrast agents in the context of their apparent clinical safety and cost-benefit ratio.

Lumbar myelography with iohexol and metrizamide. A comparative multicenter prospective study.

Diagnostic quality and adverse reactions associated with metrizamide and iohexol as contrast agents for lumbar myelography were compared in a prospective randomized double-blind study in 350 patients at seven centers. Both contrast media were administered in comparable volumes at a concentration of 180 mg I/ml. Overall quality of radiographic visualization was graded as "good" or "excellent" in 95% of 175 metrizamide studies and in 98% of 175 iohexol myelograms. Ninety-three patients examined with metrizamide (53%) and 130 patients studied with iohexol (74%) experienced no discomfort during or after myelography. The incidence of postmyelographic headache was 38% with metrizamide and 21% with iohexol. Nausea and vomiting were also more common with metrizamide. Five patients examined with metrizamide (3%) experienced transient confusion and disorientation after lumbar myelography. No such reactions were observed after iohexol myelography.

Normal pituitary gland: 2. Microscopic anatomy-CT correlation.

Pituitary microadenomas may present with subtle or no mass effect. They may appear lucent, dense, or heterogeneous on computed tomographic (CT) images. The normal pituitary gland may also have a nonhomogeneous CT appearance with intermingled lucent and dense areas. This heterogeneity is related in part to microscopic variation within the anterior and posterior lobes. Thirteen autopsy specimens of the pituitary gland were examined by coronal CT and histologically sectioned in similar coronal planes. The CT-lucent and CT-dense areas of the anterior and posterior lobes were correlated with corresponding areas on microscopic examination. To determine the effects of contrast infusion during CT, density measurements of lucent and dense areas in the anterior lobes of 26 normal contrast-enhanced pituitary glands in vivo were compared with density measurements of adjacent vascular structures at the time of scanning. Microscopic features corresponding to increased CT density in the anterior lobe included increased tissue compactness and increased cellular granularity, both of which usually occurred together in areas composed of tightly compacted and heavily granulated acidophilic cells. Conversely, microscopic features corresponding to decreased CT density in the anterior lobe included decreased tissue compactness and decreased cellular granularity, both of which frequently occurred together in areas containing chromophobic and/or mildly to moderately granulated basophilic cells. The degree of contrast enhancement within the anterior lobe appeared primarily to depend on vascularity, which in turn often depended on the degree of tissue compactness. In the posterior lobe, CT-lucent areas appeared to correspond to less compact and/or less vascular neurohypophyseal tissue.

Reformatted imaging to define the intercommissural line for CT-guided stereotaxic functional neurosurgery.

Functional stereotaxic neurosurgery has traditionally required definition of the line between the anterior and posterior commissures as the basis for defining the target site for a procedure such as stereotaxic thalamotomy. While axial computed tomographic (CT) imaging precisely defines the third ventricle and the commissures, the planes of the axial images are not necessarily parallel to the important intercommissural line. A technique is described in which coronal oblique reformations are obtained, with the reformations passing through both the anterior and posterior commissures. Stereotaxic coordinates of the target obtained from this reformatted image are directly transferable to the CT-compatible Leksell frame. Both imaging and surgery are performed on the scanner, which is located in an operating room especially designed for CT-guided surgical procedures.

Embolization of intramedullary arteriovenous malformations of the spinal cord.

Intramedullary spinal cord arteriovenous malformation (AVM) can be a devastating disease. It is not usually amenable to surgery without producing severe neurologic deficit. Previously, the risk of cord ischemia was considered a contraindication to therapeutic embolization. Three patients with intramedullary spinal cord AVMs were examined and treated using polyvinyl alcohol foam, mixed with Gelfoam in two cases. In all three cases there was marked improvement, in two to complete normalcy and in the other to near-normalcy. Successful therapy involves the appropriate angiographic mapping, choice of embolus size and composition, and challenge of function by either test occlusion or long perfusion with contrast material.

Cerebellar venous angioma: "benign" entity?

Four patients with bleeding venous angiomas in the cerebellar hemispheres are reported. All of the hemorrhages were subacute; three were recurrent. A literature review substantiated venous angioma as a recognized source of spontaneous cerebellar hemorrhage. Cerebellar venous angiomas may be more prone to bleed than venous angiomas in other locations. Their natural history seems to be similar to that of arteriovenous malformations. Though a minority bleed, the hemorrhagic event can be acute or subacute, recurrent, or catastrophic. Thus the clinical course is not always innocuous.

Neuroradiologic aspects of pediatric orthotopic liver transplantation.

To investigate the occurrence of neurologic symptomatology in pediatric orthotopic liver transplantation patients and to evaluate the utility of CT in uncovering the origin of their symptoms, we reviewed the medical records and head scans (when performed) of 71 patients. Neurologic problems occurred in 48%; the majority involved seizures, mental status changes, or coma. Patients who only had seizures generally had negative CT scans, except for two patients with minimal subarachnoid hemorrhages. Three-quarters of the comatose patients, however, had significant intracerebral hemorrhages defined by CT. Prominent sulci and ventricles were found in approximately one-third of the patients scanned, but did not correlate with symptomatology or steroid dose.

Anatomy of the brainstem: correlation of in vitro MR images with histologic sections.

MR imaging was performed on three formaldehyde-fixed brainstem specimens that were sectioned in the axial plane and myelin stained. The histologic sections were used to identify and label the structures demonstrated on short TR/TE axial MR images. Fiber tracts and nuclei that cannot be resolved on in vivo scans were well delineated by in vitro MR. Improved gray-white differentiation may be due to much greater T1 shortening of gray matter relative to white matter after fixation. The excellent anatomic detail provided by these scans should facilitate comparison of clinical scans with histologic sections.

Serial MR after bone marrow transplantation in two patients with metachromatic leukodystrophy.

Two children with metachromatic leukodystrophy underwent bone marrow transplantation. In both patients MR subsequently showed, first, white matter changes, then later, lack of change as the patients stabilized clinically.

Steady-state free precession imaging of the inner ear.

The authors describe a steady-state free precession technique for imaging the inner ear. Although the signal-to-noise ratio is not as great as with other three-dimensional MR techniques, the inherent high contrast of inner ear structures makes this a valuable technique for patients with sensorineural hearing loss and for those who refuse paramagnetic contrast material.