Biomedical subjects
Publications and source records attributed to J E Knake.
A case of acute cervical epidural abscess is presented. The use of intraoperative spinal sonography is discussed as a valuable adjunct in the evaluation and treatment of these uncommon lesions.
Thirty patients in whom the initial diagnosis of multiple sclerosis was clinically entertained underwent cranial magnetic resonance imaging (MRI) in close temporal relationship to cranial x-ray computed tomography (CT), electrodiagnostic studies (visual evoked responses, brainstem auditory evoked responses, and somatosensory evoked responses), and cerebrospinal fluid analyses (oligoclonal bands, myelin basic protein, and IgG/albumin ratio). In 26 of the 30 patients, MRI demonstrated lesions consistent with multiple sclerosis that corresponded, at least in part, with the clinically expected neuroanatomical lesion distribution. Two of the 4 patients with normal MRI had normal electrodiagnostic studies and cerebrospinal fluid analyses, and the other 2 had a single abnormal or equivocal electrodiagnostic study. All 26 patients with abnormal MRI had at least one other abnormal laboratory test. CT revealed only the largest lesions, and in the patients with abnormal CT, MRI demonstrated even more lesions. MRI, in this limited series, proved to be a strong tool in the initial diagnosis of multiple sclerosis; it may prove to be the single best test, with a sensitivity exceeding that of electrodiagnostic studies and cerebrospinal fluid analysis.
The authors examined 19 patients with diffuse histiocytic lymphoma of the brain, including 8 with primary disease and 11 with secondary disease. Both primary disease and secondary disease involving the brainstem and deep nuclei exhibited the characteristic CT appearance, consisting of a large, solid, homogeneously enhanced mass with varying amounts of edema. However, most secondary lymphomas outside the brainstem and basal ganglia contained large areas of low attenuation consistent with necrosis. Multifocal lesions were seen only in patients with secondary lymphoma. Systemic chemotherapy for extracranial lymphoma had no effect on the CT appearance of intracranial lesions. The authors suggest that these "unusual" CT patterns are actually typical of a distinct subset of histiocytic lymphomas.
Epidermoidomas were found in four locations within and adjacent to the temporal bone: cerebellopontine angle, petrous apex, facial geniculate ganglion region, and tympanic-mastoid cavity. Lesions in each of these locations presented different clinical and imaging characteristics. Cerebellopontine angle epidermoidomas were seen on computed tomography (CT) as low-attenuation masses in the posterior fossa. Petrous apex and geniculate ganglion region lesions destroyed and expanded the bone of their respective regions. Tympanic-mastoid cavity epidermoidomas were relatively nonspecific, soft-tissue masses. CT study of the brain and temporal bone was the single most informative imaging procedure in the preoperative evaluation of these lesions. Magnetic resonance images complemented CT scans for evaluation of the size and extent of the abnormality but were relatively nonspecific and did not allow preoperative differentiation of epidermoidomas from other temporal bone lesions.
Posttraumatic progressive myelopathy (PTPM) was studied in nine patients and grouped into three categories on the basis of characteristic radiographic findings and response to therapy: (a) myelomalacia with no cystic degeneration, which has poor response to therapy; (b) small cysts, with poor response to therapy; and (c) large cysts, which are effectively treated by decompression. One type dominated in each patient, although a mixture of types was present in each. Magnetic resonance (MR) imaging gave slightly improved resolution and specificity of type, decreased morbidity, and simplification of procedure in comparison with imaging by delayed computed tomographic metrizamide myelography (DCTM). DCTM and MR imaging results correlated nearly equally with those of intraoperative sonography (IOS) and pathologic study at surgery. IOS was superior to DCTM or MR imaging in detecting septations and small additional cysts. IOS also was helpful in myelotomy positioning, shunt placement, and verification of cyst decompression. MR imaging may replace DCTM in the preoperative evaluation of PTPM, followed by IOS imaging as indicated. Patients with nonmyelopathic signs and symptoms (e.g., radiculopathy) probably still require study with conventional and/or CT myelography.
Intraoperative sonography is becoming increasingly important in neurosurgery. In this article, the authors provide step-by-step instructions, the basics of lesion localization, sonographic characteristics of the more common brain and spine lesions, and tables of references to sonographically described lesions in the literature.
Intraoperative sonography is rapidly becoming a key diagnostic tool within the operative suite. Important applications are defined within the abdomen, vascular system, and other regions of the body. Intraoperative scanning may better define the normal anatomy and target pathology than preoperative studies. As with neurosurgical applications of intraoperative ultrasound, with the use of high-resolution, high-frequency real-time transducers, multiple transducer frequencies within one probe, and probe shapes specifically designed for certain types of operations, it is anticipated that the surgical use of intraoperative ultrasound will greatly increase in the future.
A symptomatic collection of spinal canalicular gas of degenerative origin was observed by computed tomography. Relief of symptoms followed gas aspiration. The collection involved the lateral recess. Such gas collections do not appear to represent benign, transient entities in all patients.
A prominent internal occipital protuberance was misdiagnosed as a fourth ventricular mass. The primary error was inattention to head positioning. The case is presented both to call attention to the need for careful topographic overlap and to discuss the interesting but normal variant.
A review of 50 anatomical specimens and 100 routine CT scans of the chest and abdomen demonstrated that ossification in the cephalic attachment of the ligamentum flavum is a common anatomical finding, but not as common on CT. Examination of hospital charts and plain radiographs of 26 patients with such ossification suggests that it is probably a normal variant; there was no evidence that it is related to diffuse idiopathic skeletal hyperostosis (DISH) or inflammatory arthropathy. Marked ossification may cause or contribute to neurological symptoms.
Real-time sonography was performed during spinal surgery in eight adult patients with seven different types of lesions. Cervical, thoracic, and lumbar lesions were included. All were examined prior to dural opening, using the saline-filled wound for water-path imaging. Five extramedullary masses and two intramedullary cavities were well delineated, allowing optimal surgical access to be determined at the moment of approach. Sonography also was abnormal in one case of diffuse spinal cord expansion, but no tissue sonographically distinguishable from spinal cord substance could be identified. Adequacy of surgical treatment was evaluated by repeat sonography before dural closure in one case of extramedullary mass and two cases of intramedullary cavities. Sonography is both reliable and beneficial during surgery for a variety of intraspinal lesions.
Sixty-four consecutive primary or metastatic brain tumors were reviewed to assess the efficacy of intraoperative sonography for localization, biopsy, and/or drainage. In 12 cases, preoperative CT data were incomplete or confusing, usually due to low-density, non-enhanced areas in which low-grade tumor could not be reliably differentiated from necrosis, edema, or cyst. In each case, intraoperative sonography clarified the nature of the solid tumor component by its distinct hyperechogenicity, facilitating biopsy. As a guide to surgical biopsy of brain tumors, sonography has some advantages even over stereotactic systems, which depend upon accurate CT definition of the lesion.
Lumbar myelography was performed in 38 patients; 19 received iohexol (an investigational aqueous contrast agent) and 19 received metrizamide. Iohexol is stable in solution, which is not the case with metrizamide. There was no other significant difference in diagnostic utility or quality between the two media. However, there was considerable postmyelography morbidity in the metrizamide group, but no postmyelography morbidity in the iohexol group. Preliminary clinical evidence suggests that iohexol is significantly superior to metrizamide as a contrast agent for lumbar myelography.
Real time intraoperative sonography is a valuable tool for visualizing subcortical mass lesions. Although most solid lesions are hyperechogenic, little is known about the ultrasound characteristics of intracerebral hemorrhage and subsequent hematoma formation. We sought to determine the sonographic characteristics of an acute intracerebral hematoma, to study its evolution, and to explore factors responsible for its echogenicity. Acute intracerebral hematomas were created in adult mongrel dogs using heparinized or unheparinized autologous whole blood injected under sonographic visualization into the centrum semiovale of 10 cerebral hemispheres. Different components of blood were also imaged in polyurethane test tubes (n = 56) immersed in a degassed, room temperature water bath. All studies were performed with continuous ultrasound recording using the ATL real time Neurosector scanner with the variable 3-, 5-, and 7.5-MHz transducer. Intracerebral hematomas were initially hypoechogenic, becoming hyperechogenic between 16 and 23 seconds after injection (average, 22 seconds). Full echogenicity was obtained between 40 and 213 seconds after injection (average, 91 seconds). There was no difference between the sonographic appearances of hematomas formed with whole blood and those formed with heparinized whole blood. In addition, we demonstrated the superior sensitivity of the 7.5-MHz frequency in visualizing intracerebral hematomas in vivo, as opposed to the 3- and 5-MHz frequencies. Whole blood, heparinized whole blood, and citrated whole blood were found to be highly echogenic in vitro. Phosphate-buffered saline, plasma, serum, and packed red blood cells (PRBCs) were hypoechogenic. Resuspended PRCBs in phosphate-buffered saline, plasma, or serum were echogenic. Our data suggest that hyperechogenicity is independent of the clotting mechanism and is related to blood stasis.(ABSTRACT TRUNCATED AT 250 WORDS)
Lumbar myelography was performed in 50 patients; 25 received iohexol (an investigational aqueous contrast agent) and 25 received metrizamide. The two media produced radiographs of equal quality. However, iohexol is stable in solution, while metrizamide is not. Further, markedly less morbidity resulted from iohexol. These features indicate that iohexol may be superior to metrizamide as a contrast agent for lumbar myelography.
Twenty-four atherosclerotic extracranial carotid artery aneurysms were encountered in 21 patients during a 25-year period. These represented 46% of all extracranial carotid artery aneurysms diagnosed at the University of Michigan during this period. Neurologic symptoms including amaurosis fugax, transient ischemic attacks, and stroke were present in 50% of the patients. An asymptomatic pulsatile neck mass occurred in 33%. Surgical therapy was undertaken for 18 aneurysms, and nonoperative treatment was pursued in the remaining six aneurysms. Operative therapy included 14 aneurysmectomies and four aneurysmorraphies. There were no surgical deaths. Transient perioperative neurologic deficits affected three of these patients (17%), and one individual (5%) experienced a permanent deficit. Transient cranial nerve deficits occurred in three patients (17%), and a permanent deficit was noted in one patient (5%). During a 7.6-year follow-up period no late strokes occurred among patients who were operated on. Nonoperative therapy was associated with three ipsilateral strokes during a mean follow-up period of 6.3 years. Atherosclerotic extracranial carotid artery aneurysms were associated with an exceptionally high stroke rate (50%) if treated nonoperatively. Prevention of late stroke justifies surgery, although perioperative neurologic deficits may accompany this therapy more often than with nonatherosclerotic carotid artery aneurysms.
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Eight patients who had facial nerve neuromas were examined, and the radiographic findings are reported. Thin section tomography, high resolution computed tomography, posterior fossa computed tomography, and cerebellopontine angle cisternography using Pantopaque (iophendylate) demonstrated bone erosions and soft tissue masses conforming to the course of the facial nerve. The lesions generally exhibited either a proximal or a distal pattern of nerve involvement. Radiologic imaging frequently permits a correct preoperative diagnosis and accurate definition of the extent of facial nerve neuromas, assessments that are important for proper patient management.