The effect of pregnancy on the response to blood loss in a rat model

STUDY OBJECTIVES

A commonly held belief is that the blunted hemodynamic response to hemorrhage observed in pregnant women is secondary to expanded blood volume. In addition to increased blood volume, pregnancy is also a vasodilated state. Vasodilatation may have deleterious effects on the response to hemorrhage by inhibiting central blood shunting after blood loss. How these conflicting variables of increased blood volume and vasodilatation integrate into a whole body model of maternal hemorrhagic shock has yet to be studied in a controlled experiment. We tested the null hypothesis that there would be no difference in the hemodynamic and metabolic responses to hemorrhage between pregnant (PRG) and non-pregnant (NPRG) rats.

METHODS

Twenty-four adult female Sprague-Dawley rats (12 PRG and 12 NPRG) were anesthetized with Althesin via the intraperitoneal route. Femoral arteries were cannulated by cut-down. Twelve (six PRG and six NPRG) rats underwent controlled catheter hemorrhage of 25% of their total blood volume. Twelve rats (six PRG and six NPRG) served as non-hemorrhage controls. Mean arterial pressure (MAP) and base excess (BE) were measured pre-hemorrhage and then every 15 min post-hemorrhage for the next 90 min. Data were reported as mean+/-standard error of the mean (S.E.M.) over the 90-min post-hemorrhage observation period. Group comparisons were analyzed by ANOVA with repeated values post-hoc by Bonferroni. Statistical significance was defined by an alpha=0.05.

RESULTS

PRG and NPRG rats were evenly matched for MAP (P=0.788) and BE (P=0.146) pre-hemorrhage. Post-hemorrhage there were no mortalities in either group. Post-hemorrhage both the PRG and NPRG groups experienced significant (P=0.011) drops in systolic and diastolic blood pressures as compared to their non-hemorrhage controls. Post-hemorrhage there was no significant (P=0.43) difference in MAP between the PRG (89+/-2 mmHg) and NPRG (80+/-2 mmHg) rats. BE also dropped significantly within both PRG (P=0.004) and NPRG (P=0.001) groups post-hemorrhage. No significant (P=0.672) difference was noted in BE between PRG and NPRG groups post-hemorrhage -6.1+/-0.3 mEq/l and -6.9+/-0.4 mEq/l, respectively.

CONCLUSION

After a controlled hemorrhage of 25% of total blood volume we found no significant differences in MAP and BE between pregnant and non-pregnant rats. Pregnancy does not affect the response to hemorrhage.

Using a fading procedure to increase fluid consumption in a child with feeding problems

Stimulus fading was combined with differential reinforcement and extinction to increase intake of a calorie-dense fluid by a 6-year-old child with feeding problems. The fading procedure consisted of adding Carnation Instant Breakfast and then milk to water (a fluid the child would drink).

Functional analysis of aberrant behavior maintained by automatic reinforcement: assessments of specific sensory reinforcers

The purpose of this study was to develop a systematic functional assessment package for aberrant behaviors maintained by nonsocial (automatic) reinforcement. The assessment package included four components: (1) functional analysis, (2) antecedent assessment of specific automatic reinforcement sources, (3) stimulus preference assessment, and (4) treatment evaluation. Functional analysis data indicated automatic reinforcement functions of the stereotypy exhibited by a 10-year-old male and the self-injury (SIB) exhibited by a 30-year-old male. Antecedent assessments of sensory classes indicated that auditory stimulation and tactile stimulation were associated with stereotypy and SIB, respectively. A multiple-stimulus-without-replacement procedure was conducted with each participant to identify the most- and least-preferred stimuli within the identified sensory classes. In an attempt to validate the assessment package for each participant, a DRO procedure was implemented using a reversal design with a multielement component. DRO procedures using stimuli within the targeted sensory classes were successful in eliminating the aberrant behaviors of both participants. The results are discussed in the context of improving the methodology for assessing and treating automatically reinforced behaviors.

CT-guided percutaneous fibrin glue therapy of cerebrospinal fluid leaks in the spine after surgery

OBJECTIVE

The objective of this study is to assess CT-guided percutaneous injection of fibrin glue for the management of cerebrospinal fluid leaks within the spine.

CONCLUSION

Percutaneous CT-guided placement of fibrin glue can provide a treatment option for postoperative cerebrospinal fluid leaks, potentially allowing a major surgical procedure to be avoided. However, the complication of aseptic meningitis may occasionally result from this procedure.

Recent advances in the assessment of aberrant behavior maintained by automatic reinforcement in individuals with developmental disabilities

Many aberrant behaviors exhibited by individuals with developmental disabilities are maintained by "automatic reinforcement". These behaviors are often difficult to treat, with the most effective behavioral interventions often resulting in only moderate success. However, a series of recent studies has advanced our ability to understand and treat these behaviors through the innovative use of behavioral assessment. We review the recent development of three categories of assessments: (a) nonhypothesis-based stimulus preference assessments, (b) hypothesis-based stimulus preference assessments, and (c) hypothesis-based assessments incorporating noncontingent reinforcement and sensory extinction procedures. We consider each category's contribution to both our ability to prescribe effective behavioral interventions and our ability to more fully understand the concept of automatic reinforcement.

Irreducible palmar metacarpophalangeal joint dislocation due to junctura tendinum interposition: a case report and review of the literature

Three different anatomic structures have been reported to prevent reduction of a palmar dislocation of metacarpophalangeal joint: dorsal capsule, palmar plate, and a ruptured collateral ligament. In our case, extensor digitorum communis of the fifth finger and extensor digiti minimi subluxated on the ulnar side of the fifth metacarpal neck. Extensor digitorum communis of the fourth finger remained in its anatomic location. The junctura tendinum connecting the fourth and fifth extensor digitorum communis tendons slipped distal and then palmar to the metacarpal head, where it was trapped between the metacarpal neck and the base of the proximal phalanx. It was easily pulled out and the joint promptly reduced. Residual subluxation persisted due to rupture of the radial collateral ligament and the dorsal capsule. Repair restored joint reduction and stability. (J Hand Surg 2000; 25A:166-172.

Echo-planar functional MR imaging of epilepsy with concurrent EEG monitoring

BACKGROUND AND PURPOSE

The role of functional MR (fMR) imaging in the evaluation of patients with epilepsy has not been systematically studied. Our purpose was to identify the fMR correlates of interictal epileptiform discharges.

METHODS

Twenty patients with epilepsy and frequent interictal discharges were studied with concurrent EEG monitoring on a 1.5-T echo-planar magnet to acquire blood-oxygenation-level-dependent (BOLD) images in the baseline (OFF) and immediate post-discharge (ON) states. Analysis was performed using subtraction of average ON and OFF data (method I); cross-correlation analysis between the ON and OFF states (method II); and individual spike analysis (ISA), with which signal intensity in the individual ON states was statistically analyzed using a weighted comparison with the mean and variance of the OFF states (method III). Agreement of fMR activation with EEG localization was determined.

RESULTS

Eighteen of 20 patients had interictal discharges during the monitoring period. Method I yielded visually detectable sites of BOLD signal differences in only one patient. Method II resulted in two patients with sites of BOLD activation. Method III, ISA, resulted in regions of increased BOLD signal corresponding to the EEG focus in nine of 10 patients.

CONCLUSION

fMR studies can often reveal sites of increased BOLD signal that correspond to sites of interictal EEG discharge activity. Because of variable intensity changes associated with discharge activity, ISA resulted in increased sensitivity.

A comparison of five tests for determining hand sensibility

Three hundred seventeen normal fingers and 612 fingers in 153 hands with carpal tunnel syndrome were tested for sensibility using the Weinstein Enhanced Sensory Test (WEST) with calibrated monofilaments, by static two-point discrimination (s2PD) and moving two-point discrimination (m2PD), using the Disk-Criminator, and by Strauch's ten test. Equivalent Semmes-Weinstein monofilament (SWM) test values were also determined as a gold standard for comparison. With both the WEST and SWM test values, the norms for interpretation have an unacceptably wide latitude because of the use of an ordinal scale of increasingly unequal intervals. With the WEST and Disk-Criminator tests, some cases of early sensory loss were missed. The SWM test apparatus, although producing relatively reliable values, is not easily portable, and its use is time-consuming in a busy office; the WEST device is prohibitively expensive. The ten test is rapid, simple, and sensitive in evaluation. It measures sensibility on a continuous analog scale, and allows for multiple points of testing in the hand, with good inter- and intra-examiner reliability. It is accurate in detecting very early loss of sensibility. In addition, the ten test requires no instrumentation.

Echoplanar MR imaging for ultrafast detection of brain lesions

OBJECTIVE

We retrospectively evaluated the use of echo-planar imaging for ultrafast detection of brain lesions.

MATERIALS AND METHODS

In our retrospective study, 61 patients were imaged with the following echo-planar sequences: single-shot proton density-weighted, single-shot T2-weighted, single-shot T2-weighted high-resolution, multishot proton density-weighted, and multishot T2-weighted. Lesions revealed in these patients ranged from 0.5 to 12.0 cm (mean, 3.7 cm) and were the result of tumor (n = 16), stroke (n = 21), demyelination (n = 18), and toxoplasmosis (n = 2). Four patients had scans with normal findings. Two neuroradiologists who were unaware of pertinent clinical data reviewed the images. The images were retrospectively compared with conventional spin-echo images for diagnosis, sensitivity of lesion detection, and qualitative criteria: subjective image quality, gray and white matter differentiation, lesion conspicuity, delineation of lesion borders, and artifacts. (Artifacts included those caused by motion, susceptibility, pulsation, and ghosting.) Quantitative criteria, including signal-to-noise and signal difference-to-noise measurements, were also evaluated in 40 lesions.

RESULTS

Sensitivity for lesion detection was 97% for single-shot echo-planar T2-weighted MR images and 100% for multishot echo-planar T2-weighted MR images. Single-shot echo-planar proton density-weighted MR images had the highest signal-to-noise ratio (91.2+/-19.3). Echo-planar T2-weighted MR images had the highest signal difference-to-noise (33.8+/-22.9). Echo-planar sequences were superior to spin-echo sequences regarding motion and pulsation artifacts. Spin-echo sequences lacked susceptibility and ghosting artifacts, and were superior in lesion conspicuity and delineation of lesion borders.

CONCLUSION

In this study, echo-planar sequences were as sensitive as conventional spin-echo imaging for the diagnostic assessment of lesions. Echo-planar sequences had a strikingly shorter acquisition time and substantially reduced motion and pulsation artifacts. Echo-planar sequences may be a useful diagnostic tool for use in claustrophobic and unstable patients.

Electromyography and magnetic resonance imaging in the evaluation of radiculopathy

Electromyography (EMG) and magnetic resonance imaging (MRI) are commonly used in the diagnosis of cervical and lumbosacral radiculopathy, but the agreement between the two studies is unknown. We retrospectively studied 47 patients with a clinical history compatible with either cervical or lumbosacral radiculopathy who were evaluated with both an EMG and a spine MRI within 2 months of each other. Among these patients, 55% had an EMG abnormality and 57% had an MRI abnormality that correlated with the clinically estimated level of radiculopathy. The two studies agreed in a majority (60%) of patients, with both normal in 11 and both abnormal in 17; however, only one study was abnormal in a significant minority (40%), suggesting that the two studies remain complementary diagnostic modalities. The agreement was higher in patients with abnormal findings on neurologic examination, underscoring the difficulty of confirming the diagnosis in mild radiculopathy.

Electromyography and magnetic resonance imaging in the evaluation of radiculopathy

Electromyography (EMG) and magnetic resonance imaging (MRI) are commonly used in the diagnosis of cervical and lumbosacral radiculopathy, but the agreement between the two studies is unknown. We retrospectively studied 47 patients with a clinical history compatible with either cervical or lumbosacral radiculopathy who were evaluated with both an EMG and a spine MRI within 2 months of each other. Among these patients, 55% had an EMG abnormality and 57% had an MRI abnormality that correlated with the clinically estimated level of radiculopathy. The two studies agreed in a majority (60%) of patients, with both normal in 11 and both abnormal in 17; however, only one study was abnormal in a significant minority (40%), suggesting that the two studies remain complementary diagnostic modalities. The agreement was higher in patients with abnormal findings on neurologic examination, underscoring the difficulty of confirming the diagnosis in mild radiculopathy.

Inhibitory effect of chlorpromazine on nematode eggs and larvae

Chlorpromazine inhibited the hatching of eggs of the parasitic nematode Haemonchus contortus and the free-living nematode Caenorhabditis elegans. In both species, hatching occurred at a concentration of 100 microg/ml but was almost totally blocked at 400 microg/ml. In the case of C. elegans, the effect was shown to be reversible by removal of chlorpromazine after exposure of the eggs to the drug for 1 hr. Caenorhabditis elegans larvae that hatched in a chlorpromazine concentration of 100 microg/ml were killed, but those that hatched in a concentration of 6.25 microg/ml were not. Taken together with data published by others, these observations indicate that the first-stage larva of C. elegans is less sensitive to chlorpromazine than is the adult worm.

FLAIR and HASTE imaging in neurologic diseases

The need to develop faster imaging techniques has led to the implementation of fast spin-echo imaging, EPI, and hybrid imaging techniques. This article discusses two of these faster imaging techniques, fast fluid-attenuated inversion-recovery (FLAIR) imaging and half-Fourier acquisition single-shot turbo spin-echo (HASTE) imaging, and their potential clinical application in neurologic diseases. FLAIR imaging, in particular, has demonstrated considerable promise for the evaluation of intracranial pathology. HASTE imaging can be used for rapid imaging of the brain or spine in those patients who are claustrophobic or who have difficulty remaining still, but it does not yet have a primary role in clinical neuroradiology.

Negative mammograms in symptomatic patients with breast cancer

RATIONALE AND OBJECTIVES

To determine the limitations of mammography in symptomatic patients.

MATERIALS AND METHODS

Approximately 20,000 mammograms obtained during a 2-year period were correlated with the results of a retrospective review of the pathology database, which revealed 711 patients with breast cancer. A total of 496 of these patients underwent mammography at the authors' institution. Three observers reviewed the mammograms of patients with "normal" mammograms within 6 months of excisional biopsy. The parenchymal patterns were also assessed.

RESULTS

Mammographic abnormalities were identified in 481 cases (97%), and 15 mammograms (3%) were interpreted as "unremarkable." Fourteen of the unremarkable cases were available for review, which indicated nine true-negative findings, one technical error, two observer errors, and two combined technical and observer errors. The technical error involved the lower inner quadrant of the breast, adjacent to the chest wall. All 14 mammograms were of dense breasts.

CONCLUSION

Mammographic abnormalities were identified in nearly all patients with proved breast cancer. Mammograms in which lesions were missed were of dense breasts, but one-third of the lesions were visible in retrospect. When examining symptomatic patients with dense breasts, radiologists should use optimal mammographic techniques and consider using nonmammographic breast imaging modalities.

Half-fourier acquisition single-shot turbo spin-echo (HASTE) MR: comparison with fast spin-echo MR in diseases of the brain

PURPOSE

To compare an ultrafast T2-weighted (half-Fourier acquisition single-shot turbo spin-echo [HASTE]) pulse sequence with fast spin-echo T2-weighted sequences in MR imaging of brain lesions.

METHODS

Fast spin-echo and HASTE images of 34 consecutive patients over the age of 50 years or with suspected demyelinating disease were reviewed independently by two neuroradiologists for the number of lesions less than 5 mm and greater than or equal to 5 mm, and for lesion conspicuity, gray-white matter differentiation, and extent of periventricular confluent signal abnormality. The reviewers also assessed for the presence of hemosiderin and extent of motion artifacts.

RESULTS

Per patient, the mean number of 5-mm or larger lesions detected on fast spin-echo images (1.4) relative to the number detected on HASTE images (0.8) was not statistically significant. For lesions less than 5 mm, fast spin-echo images showed more lesions (7.5) than HASTE images did (2.4). The fast spin-echo images were better at depicting gray-white matter differentiation, conspicuity of lesions, and periventricular signal abnormality. Of four T2 hypointense lesions seen on fast spin-echo images, none was detected on HASTE images.

CONCLUSION

Although the HASTE technique might be useful for rapid imaging of the brain, our study shows a diminished sensitivity for the detection of lesions less than 5 mm in diameter and for T2 hypointense lesions.

Enhanced ability of third-stage larvae of Haemonchus contortus to withstand drug exposure following chemically induced exsheathment

Normal (ensheathed) and exsheathed third-stage larvae of Haemonchus contortus were exposed in vitro to various concentrations of levamisole or ivermectin. Exsheathment was induced by brief exposure to sodium hypochlorite. When observed approximately 2 min after immersion in levamisole at 0, 5, 10, and 100 micrograms/ml (3 trials), the mean percentage motility (to nearest whole number) of normal larvae was 84, 43, 37, and 15, respectively. However, the mean percent motility of exsheathed larvae was 77, 78, 79, and 72, respectively. When observed 55 min after immersion in levamisole at the same concentrations, the mean percent motility of normal larvae was 76, 4, 3, and 0, respectively, whereas that for exsheathed larvae was 72, 75, 68, and 0. When observed 45 min after initial exposure to ivermectin at 0, 8, 80, and 160 micrograms/ml, the mean percent motility of normal larvae was 87, 6, 3, and 3, respectively, whereas the mean percent motility of exsheathed larvae was 94, 75, 29, and 14, respectively. Thus, both drugs were effective against both kinds of larva; but the time and concentration required for efficacy were markedly affected by the presence or absence of a sheath or by unknown effects of the exsheathment process. For both levamisole and ivermectin, exsheathed larvae had a much greater ability than normal larvae to withstand drug exposure.

Intraneural mucous cysts of peripheral nerves

We present three cases of a rare mucous cyst inside the peripheral nerves of the upper extremity; a lateral cutaneous nerve of the forearm, a dorsal sensory branch of the ulnar nerve, and a median nerve at the wrist. All our cases were intraneural, and we excised longitudinal strips of the cyst wall between nerve fascicles in all, preserving nerve function in each case.

Transverse bayonet dislocation of the distal interphalangeal joint--a case report

Transverse bayonet dislocation of an interphalangeal joint is an unstable injury caused by the disruption of both collateral ligaments. This injury pattern in proximal interphalangeal joint was first described by Patel et al. (Clin Orthop Rel Res. 1978;133:219), who coined the term "bayonet dislocation" to describe this particular type of injury. The case of a distal interphalangeal transverse dislocation is presented. This dislocation was successfully treated by closed reduction and immobilization with an aluminum splint and buddy taping to the adjacent finger.

Percutaneous fibrin glue therapy of meningeal cysts of the sacral spine

OBJECTIVE

We assessed CT-guided percutaneous injection of fibrin glue to manage meningeal cysts of the sacral spine in patients with back pain.

CONCLUSION

All patients experienced resolution or marked improvement of symptoms for as long as 23 months after fibrin glue therapy. No patients experienced recurrence of symptoms during the follow-up interval. Percutaneous CT-guided fibrin glue therapy for sacral meningeal cysts may be a more definitive therapy than repetitive cyst aspiration.

Percutaneous release of trigger digit with and without cortisone injection

Percutaneous release was done using the tip of an 18-gauge, 2.5-cm-long needle, mounted on a 3-mL3 syringe in 225 trigger digits. It was successful in 92 (89%) of the digits without cortisone injection (n = 105) and in 115 (96%) of the digits with cortisone injection (n = 120). Negligible or intermittent pain persisted for 8 weeks in the noncortisone group and 6 weeks in the cortisone group after percutaneous release. Of the first 10 digits, 2 needed repeat percutaneous release. With modification of technique, the incidence of repeat percutaneous release was zero in both groups. Open release was needed in 8% in the noncortisone group and 3% in the cortisone group. The procedure was done under local infiltration anesthesia in the office. This reduced patient anxiety, inconvenience and hospital cost.

Detection of hyperacute primary intraparenchymal hemorrhage by magnetic resonance imaging

BACKGROUND

MRI has become increasingly used in the acute setting to manage patients with stroke. There has been concern that MRI may not be sensitive in the detection of acute intracranial hemorrhage. We assessed whether strongly susceptibility-weighted MRI would be sensitive to intraparenchymal hemorrhage in the first few hours.

CASE DESCRIPTIONS

In the course of our ongoing studies of MRI of acute ischemic stroke in more than 200 patients, 35 patients had MR studies within 6 hours. Six of these patients who presented with acute focal symptoms with definite time of clinical onset (2.5 to 5 hours) were found to have evidence of intraparenchymal hemorrhage. Standard T1- and T2-weighted MR scans were performed. In 5 of the patients, echo-planar imaging and gradient-echo sequences were performed to increase the sensitivity of magnetic susceptibility effects of the pulse sequences. Four of the cases were of putaminal hemorrhage and 2 were lobar hemorrhages. The hemorrhage was most evident as foci of T2* hypointensity (signal loss) and unambiguous on the more susceptibility-weighted sequences, particularly echo-planar gradient-echo images.

CONCLUSIONS

MRI can detect hemorrhage within 2.5 to 5 hours of onset of clinical symptoms as regions of marked signal loss due to susceptibility effects, whereas conventional MR scans of ischemic stroke may appear normal. These results demonstrate that MR susceptibility sequences may be sensitive to hyperacute hemorrhage and suggest that MR may be an adequate screen for primary intraparenchymal hemorrhage.

MR angiography of the head and neck

A review of the basic physics and techniques for acquiring and evaluating magnetic resonance angiograms is provided, including time-of-flight and phase contrast techniques. Magnetic resonance (MR) angiography is becoming a routine method of evaluating carotid bifurcation atherosclerotic disease in both a screening and diagnostic capacity. The expanding clinical utility of MR angiography in the detection of intracranial aneurysms, characterization of arteriovenous malformations, and evaluation of intracranial atherosclerotic disease are also reviewed. Furthermore, MR angiography allows for the noninvasive diagnosis of arterial dissection. Magnetic resonance venography also allows the confirmation of the previously elusive and likely underdiagnosed entity of cerebral venous thrombosis.

Multiple schwannomas of the ulnar nerve: a case report

Multiple schwannomas may occur as visible tumors or may occur as tumors in situ. The tumors in situ may be missed when the visible tumors are excised. In time, the schwannomas in situ grow and appear to be recurrent, while in fact, they are multicentric. The prognosis on multicentric schwannomas thus remains guarded.

EEG-triggered echo-planar functional MRI in epilepsy

We investigated whether: (1) EEG recordings could be successfully performed in an MRI imager, (2) subclinical epileptic discharges could be used to trigger ultrafast functional MRI images, (3) artifact-free functional MRI images could be obtained while the patient was having the EEG monitored, and (4) the functional MRI images so obtained would show focal signal increases in relation to epileptic discharges. We report our results in two patients who showed focally higher signal intensity, reflective of increased local blood flow, in ultrafast functional MRI timed to epileptic discharges recorded while the patients were in the imager and compared with images not associated with discharges. One patient showed a focal increase despite a clinical and EEG history of generalized discharges. This approach may have the potential to identify brain regions activated during brief focal epileptic discharges.

M6P/IGF2 receptor: a candidate breast tumor suppressor gene

The mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2r) functions in the activation of TGFbeta, a potent growth inhibitor for most cell types, the degradation of the mitogen, IGF2, and the intracellular trafficking of lysosomal enzymes. We have found its expression to be significantly reduced in both rat and human hepatocellular carcinomas (HCCs) and recently reported loss of heterozygosity (LOH) at this locus with mutations in the remaining allele in human liver tumors. Using the polymerase chain reaction, we utilized two polymorphisms in the 3' untranslated region of M6P/IGF2r to screen breast tumors for LOH. Forty of 62 (65%) patients were informative (heterozygous) and 12/40 (30%) breast tumors had LOH; 5/19 (26%) carcinomas in situ (CIS) and 7/21 (33%) invasive carcinomas. To investigate the early molecular genetic events in breast carcinogenesis, we screened the CIS with LOH for mutations. In 2/5 (40%) of these tumors, missense mutations were found in the remaining allele that gave rise to significant amino acid substitutions. These findings provide evidence that M6P/IGF2r allelic loss is an early event in the etiology of breast cancer, that this gene functions as a tumor suppressor gene in the breast.

Intraepineurial constriction of nerve fascicles in pronator syndrome and anterior interosseous nerve syndrome

In PS or AINS, if obvious epineurial compression deformity of the median nerve or the AIN is not found at known sites of compression, IeCNF should be considered. IeCNF may occur in one or more nerve fascicles of the median nerve at one of multiple levels in the distal upper arm and proximal forearm. Decompression of the nerve fascicles is achieved by epineurotomy, microsurgical interfascicular dissection, and removal of the constricting outer layer of the perineurium above and below the elbow. Resection of the constricted segments of the nerve fascicles is not necessary. Intraepineurial exploration of the nerve trunk also may be considered if, after surgical decompression of PS and AINS, expected recovery has not occurred and there is no evidence of axonal degeneration.

Postoperative cerebrospinal fluid leaks of the lumbosacral spine: management with percutaneous fibrin glue

PURPOSE

To assess CT-guided injection of fibrin glue for the management of lumbosacral cerebrospinal fluid (CSF) leaks.

METHODS

Six consecutive patients with postoperative CSF leaks were treated after CSF aspiration under CT guidance. A solution of cryoprecipitate was simultaneously injected with a 10% calcium chloride solution containing 2000 units of thrombin per milliliter. In one patient, 0.5 mL of iopamidol was added to the calcium chloride/thrombin mixture before injection. Placement of the fibrin glue aggregate was confirmed by CT imaging. To determine outcomes we reviewed the patients' records, postprocedure imaging studies, and physical findings, and we interviewed the patients directly.

RESULTS

In three patients with postoperative CSF leaks, symptoms resolved after treatment. Despite imaging evidence of successful plug deployment, two other patients still had severe symptoms, and they underwent surgery after 2 and 18 hours, respectively. One patient had a continued CSF leak and a headache after 12 hours; follow-up surgery repaired an unsuspected dural tear just distal to the site of original surgery underneath the lamina and not covered by the fibrin glue. After one of the successful procedures, the patient had a fever and a headache, probably because of aseptic meningitis, which resolved after 2 days.

CONCLUSION

Percutaneous CT-guided placement of fibrin glue may provide nonsurgical treatment for postoperative CSF leaks, potentially avoiding a major and technically difficult surgical procedure.

Unusual manifestations of head trauma

Head injury is the leading cause of death in young adults. More than 2 million head injuries occur each year in the United States. Accurate and rapid diagnosis is imperative for the successful management of the trauma patient. The radiologic findings of common manifestations of head trauma have been well described; however, the patient who presents in the post-traumatic period with atypical radiographic findings is at risk for misdiagnosis and delay in treatment. In this essay, we illustrate some unusual findings in head injury that may complicate diagnosis.

Preoperative assessment of the carotid bifurcation. Can magnetic resonance angiography and duplex ultrasonography replace contrast arteriography?

BACKGROUND AND PURPOSE

Noninvasive studies are used with increasing frequency to assess the carotid bifurcation before endarterectomy. Therefore, assessment of their diagnostic accuracies is essential for appropriate patient management. We prospectively evaluate two noninvasive tests, magnetic resonance angiography (MRA) and duplex ultrasonography (DU), as potential replacements for contrast arteriography (CA).

METHODS

A blinded comparison of three-dimensional time-of-flight (TOF) MRA, two-dimensional TOF MRA, and DU in 176 arteries was performed. CA was used as the standard of comparison.

RESULTS

Three-dimensional TOF MRA had a sensitivity of 94%, a specificity of 85%, and an accuracy of 88% for the identification of 70% to 99% stenosis; two-dimensional TOF MRA had a sensitivity and specificity that were approximately 10% lower than those of three-dimensional TOF MRA. DU resulted in a sensitivity of 94%, a specificity of 83%, and an accuracy of 86%. Combining data from three-dimensional TOF MRA and DU, allowing for CA only for disparate results, yielded a sensitivity of 100%, a specificity of 91%, and an accuracy of 94% among concordant noninvasive tests, with CA required in 16% of arteries. MRA accurately differentiated 17 carotid occlusions from 16 high-grade (90% to 99%) stenoses, whereas with DU two patent arteries were identified as occluded and one occluded artery was identified as patent.

CONCLUSIONS

Three-dimensional TOF MRA is the most accurate noninvasive test. Combined use of MRA and DU results in a marked increase in accuracy to a level that obviates the need for CA in a majority of patients.

MR imaging of diseases of the brain: comparison of GRASE and conventional spin-echo T2-weighted pulse sequences

OBJECTIVE

The purpose of this study was to compare a combined gradient and spin-echo (GRASE) technique, which is a rapid T2-weighted imaging sequence, with conventional spin-echo (SE) sequences for imaging brain lesions. The GRASE sequences would allow increased patient throughput with potential cost savings and be useful in uncooperative patients without requiring echoplanar imaging techniques and specialized hardware.

SUBJECTS AND METHODS

Conventional SE and GRASE T2-weighted images of 49 consecutive patients (20-86 years old) were reviewed independently by three neurora-diologists for the presence and characterization of lesions (most of which were nonspecific foci of hyperintensity within the white matter), gray-white matter differentiation, conspicuity of lesions, and periventricular signal abnormality. The MR studies were performed on a 1.0-T Siemens Magnetom Impact scanner, with the SE images obtained using a TR/TE of 2400/40 and the GRASE images obtained using a TR/effective TE of 4400/110.

RESULTS

The number of lesions detected that were 5 mm or larger in maximal diameter did not significantly differ among techniques. For lesions smaller than 5 mm, conventional SE T2-weighted images showed more lesions (p < .01). The SE images were better than the GRASE images for assessing gray-white matter differentiation, conspicuity of lesions, and periventricular signal abnormality. The two hypointense lesions were better assessed on the conventional SE images.

CONCLUSION

Although GRASE imaging may be potentially useful for rapid imaging of the brain, our experience shows it has a markedly diminished sensitivity for detecting lesions smaller than 5 mm in diameter. Currently, GRASE imaging should not replace the routine clinical use of conventional SE sequences.

Perioperative imaging strategies for carotid endarterectomy. An analysis of morbidity and cost-effectiveness in symptomatic patients

OBJECTIVE

To assess the cost-effectiveness of four diagnostic strategies for the preoperative evaluation of symptomatic patients who are potential candidates for carotid endarterectomy (ie, 70% to 99% stenosis): (1) duplex sonography (DS), (2) magnetic resonance angiography (MRA), (3) contrast angiography (CA), and (4) the combination of DS and MRA supplemented by CA for disparate results.

METHODS

Cost-effectiveness analysis based largely on published clinical trial data. Sensitivities and specificities of noninvasive tests were estimated from 81 patients undergoing prospective evaluation with DS, MRA, and CA.

OUTCOME MEASURE

Incremental cost per quality-adjusted year of life gained.

RESULTS

For a hypothetical cohort of symptomatic patients undergoing evaluation for carotid endarterectomy, the combination of tests resulted in the greatest quality-adjusted life expectancy of the four options considered. After incorporating the costs of testing, surgery, and stroke, we found that neither the MRA nor the CA strategy was cost-effective. The combination of tests was more effective but more costly than DS, resulting in an additional cost of $22,400 per quality-adjusted year of life gained. For centers that do not have adequate MRA, CA resulted in an additional cost of $99,200 per quality-adjusted year of life saved compared with DS.

CONCLUSIONS

Our results suggest that for the preoperative detection of a 70% to 99% carotid stenosis, the combination of DS and MRA, supplemented by CA for disparate results, is associated with the lowest long-term morbidity and mortality and has a favorable cost-effectiveness ratio. The combination of tests, or DS alone when MRA is not available, could potentially replace the current practice of using CA alone in the preoperative evaluation of patients with symptomatic carotid stenosis.

Brain lesions in patients with multiple sclerosis: detection with echo-planar imaging

PURPOSE

To evaluate the detection of brain lesions with echo-planar imaging relative to conventional spin-echo (SE) imaging.

MATERIALS AND METHODS

In 17 patients (three men, 14 women; mean age, 31 years) with multiple sclerosis, the following were compared: single-shot proton-density- and T2-weighted and thin-section T2-weighted echo-planar, proton-density- and T2-weighted multishot echo-planar, and conventional SE sequences. Quantitative and qualitative criteria as well as lesion detectability were evaluated. The proton-density-weighted SE sequence was used as the standard of reference.

RESULTS

Multishot sequences were superior to single-shot sequences in image quality and lesion detectability. With the multishot proton-density-weighted sequence, 53 of 54 large lesions and 23 of 30 small lesions were detected; with the single-shot proton-density-weighted sequence, 38 of 54 large lesions and five of 30 small lesions were detected.

CONCLUSION

With multishot echo-planar sequences, detectability of large lesions is similar to that with conventional SE imaging. Susceptibility artifact is diminished in comparison to single-shot echo-planar sequences.

Diffusion and perfusion imaging techniques

Diffusion imaging techniques including the Stejskal-Tanner and the stimulated emission of amplitude echoes (STEAM) pulse sequences are discussed. The calculation of apparent diffusion coefficient (ADC) maps is reviewed. The perfusion imaging techniques of blood oxygen level dependent (BOLD) and first pass bolus perfusion techniques as well as the newer technique of echo-planar imaging with signal targeting and altering radiofrequency (EPISTAR) are also discussed. Finally, the theory of intravoxel incoherent motion (IVIM) and its relationship to both diffusion and perfusion phenomena is examined.

Stroke and ischemia

With the introduction of diffusion imaging the diagnosis and acute stroke can be made within minutes of clinical onset. In combination with perfusion imaging, tissue viability can be assessed. The etiology of ischemia can in most cases be investigated by MR angiography. The current applications of these techniques are reviewed, and pitfalls as well as problems in the diagnosis of acute stroke are discussed. With the availability of these techniques, patients can almost instantaneously be approved for pharmacotherapy and monitored and thus clinical outcome potentially can be improved tremendously.

Dissection of the carotid and vertebral arteries: imaging with MR angiography

Arterial dissection occurs when an intimal tear allows blood to enter the arterial wall, potentially compromising the lumen and reducing blood flow. Carotid and vertebral artery dissections typically occur after major trauma, although they also can arise spontaneously or after trivial injury. Arterial dissection has been associated with a variety of factors, including hypertension, fibromuscular dysplasia, Marfan syndrome, cystic medial necrosis, oral contraceptives, drug abuse (sympathomimetics), and infection [1-8]. It is important to recognize arterial dissection early so that prompt treatment can be initiated to prevent ischemic complications [1]. In this essay, we illustrate the use of MR angiography in the diagnosis of carotid and vertebral artery dissection.