Raymond F. Carmody

Epidemiologic features of asymptomatic cerebral infarction in patients with nonvalvular atrial fibrillation

We performed unenhanced computed tomographic scans on 141 asymptomatic patients with nonvalvular atrial fibrillation. Thirty-six patients (26%) had hypodense areas consistent with cerebral infarction. The majority of these were small deep infarcts, seen in 29 patients (21%), but 13 patients (9%) had cortical or large deep infarctions. Twelve patients had more than one infarct on computed tomographic scan. Increasing age and increased left atrial diameter were the only clinical features associated with asymptomatic infarction. Patients older than 65 years with a left atrial diameter greater than 5.0 cm (n = 23) had a 52% prevalence of asymptomatic infarction. Patients younger than 65 years with a left atrial diameter less than 5.0 cm (n = 38) had an 11% prevalence of silent infarction. Patients with only one of these risk factors (n = 72) had a 24% prevalence of silent infarction. Infarction was more common in those with chronic (34%) as opposed to intermittent (22%) nonvalvular atrial fibrillation, but this difference was not significant. Hypertension, diabetes, duration of atrial fibrillation, congestive heart failure, history of myocardial infarction, and echocardiographic evidence of left ventricular dysfunction were not associated with asymptomatic infarction. A history of hypertension was present in only 35% of our patients with small-deep asymptomatic infarction, similar to the percentage in patients without stroke. Asymptomatic cerebral infarction is common in nonvalvular atrial fibrillation. The association with enlarged left atria and the lack of correlation with major cerebrovascular risk factors suggests a cardioembolic mechanism. Further study is needed to determine the functional and prognostic significance of these strokes.

Bone marrow imaging using STIR at 0.5 and 1.5 T

We retrospectively examined MR images in 82 patients to evaluate the usefulness of short inversion time inversion recovery (STIR) in bone marrow imaging at 0.5 and 1.5 T. The study included 56 patients at 1.5 T and 26 patients at 0.5 T with a variety of pathologic bone marrow lesions (principally oncological), and compared the contrast and image quality of STIR imaging with spin-echo short repetition time/echo time (TR/TE), long TR/TE, and gradient-echo sequences. The pulse sequences were adjusted for optimal image quality, contrast, and fat nulling. STIR appears especially useful for the evaluation of red marrow (e.g., spine), where contrast between normal and infiltrated marrow is greater than with either gradient-echo or T1-weighted images. STIR is also extremely sensitive for evaluation of osteomyelitis, including soft tissue extent. In more peripheral (yellow) marrow, T1-weighted images are usually as sensitive as STIR. Limitations of STIR include artifacts, in particular motion artifact that at high field strength necessitates motion compensation. At 0.5 T, however, motion compensation is usually not necessary. Also, because of extreme sensitivity to water content, STIR may overstate the margins of a marrow lesion. With these limitations in mind, STIR is a very effective pulse sequence at both 0.5 and 1.5 T for evaluation of marrow abnormalities.

Syndromes of the First and Second Branchial Arches, Part 2: Syndromes

SUMMARY: A variety of congenital syndromes affecting the face occur due to defects involving the first and second BAs. Radiographic evaluation of craniofacial deformities is necessary to define aberrant anatomy, plan surgical procedures, and evaluate the effects of craniofacial growth and surgical reconstructions. High-resolution CT has proved vital in determining the nature and extent of these syndromes. The radiologic evaluation of syndromes of the first and second BA should begin first by studying a series of isolated defects (cleft lip with or without CP, micrognathia, and EAC atresia) that compose the major features of these syndromes and allow a more specific diagnosis. After discussion of these defects and the associated embryology, we discuss PRS, HFM, ACS, TCS, Stickler syndrome, and VCFS.

Syndromes of the First and Second Branchial Arches, Part 1: Embryology and Characteristic Defects

SUMMARY: A variety of congenital syndromes affecting the face occur due to defects involving the first and second BAs. Radiographic evaluation of craniofacial deformities is necessary to define aberrant anatomy, plan surgical procedures, and evaluate the effects of craniofacial growth and surgical reconstructions. High-resolution CT has proved vital in determining the nature and extent of these syndromes. The radiologic evaluation of syndromes of the first and second BAs should begin first by studying a series of isolated defects: CL with or without CP, micrognathia, and EAC atresia, which compose the major features of these syndromes and allow more specific diagnosis. After discussion of these defects and the associated embryology, we proceed to discuss the VCFS, PRS, ACS, TCS, Stickler syndrome, and HFM.

Computed tomography in hematologic malignancies of paranasal sinuses

Hematologic malignancies of the paranasal sinuses are uncommon. Four young patients with ophthalmologic abnormalities as a chief complaint are presented. Lymphoma or leukemia should be considered in the differential diagnosis of destructive lesions in the paranasal sinuses, particularly in children and young adults.

MRI diagnosis of thoracic ossification of posterior longitudinal ligament with concomitant disc herniation

SummaryOssification of the posterior longitudinal ligament is a potentially curable cause of thoracic myelopathy. As this case illustrates, MRI can confirm the diagnosis, demonstrate other concomitant pathology such as disc herniation, and help assess the clinical significance of OPLL by showing spinal word compression.

Digital subtraction angiography in head and neck radiology

SummaryIntravenous digital subtraction angiography (IVDSA) was used to evaluate 44 patients with suspected otolaryngologic abnormalities. Sixteen had IVDSA for pulsatile tinnitus or suspected glomus tumor of the petrous bone. Nine patients were evaluated because of pulsatile neck masses, and 12 others had suspected tumors of the neck, face, and paranasal sinuses. Seven had IVDSA following head and neck trauma. The technique of examination is described. The current indications of IVDSA in head and neck radiology are discussed. It is concluded that IVDSA is a suitable substitute for conventional angiography for many otolaryngologic conditions and, because of its safety, can be used more liberally.

Digital Intravenous Cerebral Angiography

A photoelectronic imaging system has been built and developed at the University of Arizona. Initial studies have been directed toward digital video subtraction angiography (DVSA) using intravenous injections of contrast material. DVSA has been applied clinically to the study of the heart, the aortic arch and great vessels, the kidneys, abdominal and lower extremity vessels, the pulmonary arteries, and the vessels of the head and neck, generally with remarkable success. This paper deals with our clinical experiences with DVSA in evaluation of the vessels of the head.

The Temporal Bone

The complex, intricate anatomy of the temporal bone makes this area one of the most difficult to master in all of neuroradiology. Moreover, the small size of many of the structures of clinical interest taxes the spatial resolution of our current generation of computed tomography (CT) and magnetic resonance imaging (MRI) scanners. While CT is the procedure of choice for imaging the bony structures in this region, MR is better for soft tissue detail (Table 29.1a). Pluridirectional tomography, once the mainstay of temporal bone imaging, is less satisfactory and is seldom used today.1–5 Plain-film radiographs have been relegated to assessing mastoid pneumatization and the position and integrity of cochlear implants.6–7 Once one has learned the radiographic anatomy of the temporal bone, recognizing pathologic changes is less difficult, because the anatomy of this area is remarkably constant.

Case 252: Acute Hyperammonemic Encephalopathy Resulting from Late-Onset Ornithine Transcarbamylase Deficiency

History A 19-year-old woman with no pertinent medical history was brought to the emergency department after being found unconscious on her bathroom floor by her roommate. In the preceding weeks, she had reported intractable nausea and vomiting, for which she had been taking ondansetron. No other medications had been prescribed. The day prior to presentation, she had contacted her mother and described increasing confusion. Glasgow coma scale score on arrival in the emergency department was 4. Intravenous naloxone was administered, without immediate response. Initial blood glucose level was 232 mg/dL (12.8 mmol/L) (normal range, 79-140 mg/dL [4.4- 7.7 mmol/L]), and other routine laboratory test results were normal. Urine toxicology results were negative. Cerebrospinal fluid evaluation revealed levels were within normal limits. Neurologic examination revealed dilated pupils, which showed a sluggish response to light, and left lower extremity rigidity with intermittent tremors. Initial unenhanced cranial computed tomographic (CT) findings were negative. Magnetic resonance (MR) imaging of the brain was performed. The patients condition deteriorated, with increasing cerebral edema over the next week, and she was declared brain dead. Her liver was transplanted into an adult recipient, who subsequently developed cerebral edema and elevated plasma ammonia levels, resulting in death in the immediate postoperative period.