Transcranial magnetic evoked potentials used to monitor the spinal cord during neuroradiologic angiography of the spine.

A current topic in intraoperative monitoring of the spinal cord is the inability of the somatosensory evoked potentials (SSEP) to adequately document anterior spinal cord function. Transcranial magnetic stimulation (TMS) of the cortex for assessing corticospinal (efferent) pathways is a developing modality. The authors demonstrate a potential application of TMS as a monitoring medium for use in the neuroradiology suite. Limitations of intraoperative applications of cortical magnetic stimulation associated with cortical suppression are caused by anesthetics and neuromuscular blockers. These limitations generally are not an issue in the neuroradiology suite. In this report, motor improvement was correctly predicted by magnetic evoked potential amplitudes, whereas an SSEP remained unchanged during neuroradiologic angiography.

MR imaging of symptomatic peripheral vascular malformations.

We performed a retrospective study of symptomatic peripheral vascular malformations to determine if MR imaging can be used to distinguish slow-flow venous malformations from high-flow arteriovenous malformations and arteriovenous fistulas. Twenty-seven MR examinations in 25 patients with malformations outside the CNS were reviewed. Sixteen venous malformations, nine arteriovenous malformations, and two arteriovenous fistulas were included. In all cases, the MR findings were correlated with the results of angiography. The distinction between slow-flow venous malformations and high-flow arteriovenous malformations and arteriovenous fistulas was made primarily on T2-weighted MR images, which showed high signal intensity in venous malformations and flow voids in high-flow lesions. In addition to the previously described MR features of venous malformations (serpentine pattern with septations, associated muscle atrophy, and typical T1 and T2 signal intensities), several new MR features were apparent. Venous malformations had a propensity for multifocal involvement (37%), orientation along the long axis of extremities or affected muscles (78%), and adherence to neurovascular distributions (64%). Prominent subcutaneous fat was commonly seen adjacent to the malformation. MR images of arteriovenous malformations and arteriovenous fistulas also commonly showed muscle atrophy and subcutaneous fatty prominence. Our results show that slow-flow venous malformations can be distinguished from high-flow arteriovenous malformations and fistulas on the basis of spin-echo MR signal characteristics. The associated imaging characteristics help in the differential diagnosis in problematic cases.

Paranasal sinuses on MR images of the brain: significance of mucosal thickening.

One hundred twenty-eight patients were examined prospectively to determine the significance of mucosal thickening seen in the paranasal sinuses during routine MR imaging of the brain. On the basis of responses to a questionnaire, each patient was categorized as symptomatic (n = 60) or asymptomatic (n = 68) for paranasal sinus disease. Patients were categorized further on the basis of the maximal mucosal thickening seen by MR in any paranasal sinus. A modified t test was used to compare the prevalence of various degrees of mucosal thickening between symptomatic and asymptomatic groups. Statistically significant differences between the groups were seen only in those patients with normal sinuses and in those with 4 mm or more of mucosal thickening. We conclude that mucosal thickening of up to 3 mm is common and lacks clinical significance in asymptomatic patients. An ancillary finding is that 1- to 2-mm areas of mucosal thickening in the ethmoidal sinuses occur in 63% of asymptomatic patients. This minimal mucosal thickening in the ethmoidal sinuses is thought to be a normal variant, possibly a function of the physiologic nasal cycle.

Ethanol embolization of arteriovenous fistulas: a primary mode of therapy.

Arteriovenous fistulas (AVFs) can be posttraumatic or congenital vascular malformations. In the initial arteriographic evaluation, chronic AVFs potentially can be confused with arteriovenous malformations (AVMs). The authors studied five patients with a single AVF and one patient with numerous AVFs. Three patients had undergone surgery for treatment of their AVFs, one patient had undergone isobutyl-2-cyanoacrylate (IBCA) embolization, and two patients had undergone no prior therapy. The AVFs recurred in the three patients who had undergone surgery and in the patient who had undergone IBCA embolization. All patients underwent ethanol embolization of their AVFs. Angiograms obtained immediately after embolization documented closure of all AVFs. At follow-up, none of the embolized lesions have recurred. The authors conclude that ethanol embolotherapy can cure these problematic lesions. Extreme caution, however, must be employed with the use of intravascular ethanol because nontarget embolization can potentially result in tissue devitalization. In this study, two patients developed a small focal area of skin necrosis that did not require skin grafting and healed with conservative management.

Ethanol embolization of vascular malformations.

Absolute ethanol was used to treat 20 patients with symptomatic vascular malformations (SVMs) (ie, venous malformations, arteriovenous malformations, and congenital and posttraumatic arteriovenous fistulas) in whom previous surgery or standard embolotherapy had failed or who were not candidates for surgery. All large complex lesions required multiple embolizations as staged procedures. Immediate thrombosis was achieved in all patients; complications (13% of cases) were generally minor and were treated conservatively. Follow-up studies, performed in 19 of 20 patients, showed persistent occlusion of the SVM in all cases. Ethanol embolization of SVMs, performed according to strict techniques, has proved efficacious in SVM management and is emerging as a definitive form of therapy.

Stereotactic breast biopsy with a biopsy gun.

One hundred three patients underwent stereotactic breast biopsy with an 18-, 16-, or 14-gauge cutting needle and a biopsy gun. After biopsy, a localization wire was placed and surgical biopsy performed. There was agreement of the histologic results in 89 cases (87%) including 14 of 16 cancers (87%) (kappa = 0.806). The gun biopsy yielded the correct diagnosis in four cases involving a lesion (including one cancer) that was missed at the surgical biopsy. Nine cases in which the lesion was missed at gun biopsy can be related to insufficient needle size, the greater difficulty in using one of the two stereotactic devices, and early inexperience with the technique. A 14-gauge needle was used in the last 29 biopsies, the results of which agreed with the surgical pathologic findings in 28 cases (97%). With greater experience, stereotactic-guided large-gauge automated percutaneous biopsy may prove to be an acceptable alternative to surgical biopsy in women with breast masses suspected at mammography.

The retrorenal colon in the supine and prone patient.

Ninety patients underwent computed tomographic scanning in both the supine and prone positions to show the orientation of the retroperitoneal colon about the kidneys and allow evaluation of changes in colonic position and contents. The data were compared with data on 500 patients scanned only when supine. Particular attention was given to bowel found posterior to the kidneys (retrorenal colon): its frequency of occurrence on 500 scans of supine patients was 1.9%, but 10.0% in the 90 prone patients. Because most invasive renal procedures would not intersect with retrorenal colon located behind the lateral one-third of the kidney, the data were reevaluated after deletion of these patients, giving a frequency in prone patients of 4.7%. This was found exclusively at the level of the lower renal poles, and the involved colon was extensively distended with gas. Attention should be given at fluoroscopy to detect this unusual, posteriorly positioned, air-filled colon before any invasive renal procedure.

Quantitation of sulfhydryl groups on erythrocytes in polycythemia vera.

The number of sulfhydryl groups on the surface of intact erythrocytes from patients with polycythemia vera is significantly less (34%) than those from control subjects. Sulfhydryl groups were measured indirectly by reversibly blocking -SH groups with the thiol reagent, 6,6'-dithiodinicotinic acid, which forms stable mixed disulfides on the surface of erythrocytes. Glutathione was used to break the disulfides and release thione into the supernatant. Thione was then quantitated spectrophotometrically.