Traumatic and spontaneous carotid and vertebral artery dissection in a level 1 trauma center.

This study aimed to compare traumatic and spontaneous carotid artery dissection (CAD) and vertebral artery dissection (VAD) with respect to age, pre-morbid risk factors, and site of dissection. Chart review was performed for 49 patients with CAD and VAD admitted to Westchester Medical Center, a level 1 trauma center, from 1999 to 2007. Presentation was categorized into traumatic (n=28, 57%) or spontaneous dissection (n=21, 43%). Pre-morbid risk factors were analyzed. Location of dissection was identified and categorized into four possible segments. Patients with spontaneous dissection were likely to be over the age of 50 years (p<0.05), and had significantly higher proportions of coronary artery disease (33% compared to 7%, p<0.05), hypertension (57% compared to 18%; p<0.01), and hypercholesterolemia (29% compared to 0%; p<0.01). Of the 49 patients, 42 had imaging studies available for segmental analysis. In both traumatic CAD and VAD, dissection at Segment III (corresponds with the first and second cervical vertebrae), was the most common site (37.5% and 50%, respectively, p<0.05). In contrast, Segment I (origin of the vessel to the fifth cervical vertebrae) was the most common site for spontaneous CAD and VAD (55% and 77%, respectively, p<0.05). This cross-sectional study suggests that etiology plays an important role in the location of dissection. Traumatic CAD and VAD occur most commonly in Segment III. Spontaneous CAD and VAD occur most commonly in Segment I and are associated with increasing age and premorbid cerebrovascular risk factors.

Effect of absorbable topical hemostatic agents on the relaxation time of blood: an in vitro study with implications for postoperative magnetic resonance imaging.

OBJECT: Absorbable topical hemostatic agents are commonly used in neurosurgery. In this study the authors examine the longitudinal relaxation time (T1) of blood in contact with these agents over time, measured in vitro, to determine if their presence could affect the interpretation of postoperative magnetic resonance (MR) images. METHODS: Coagulated and anticoagulated blood were used, both oxygenated and deoxygenated. The effects of a collagen-based agent (Collastat) and a cellulose-based agent (Surgicel) on the pH and T1 values of blood and on those of saline (used as a control) were investigated. The T1 was measured as a function of magnetic field strength and time by using a field-cycling relaxometer. This instrument measures 1/T1, the rate of T1, from which the T, value is computed. The T1 values of blood were compared with those of hemostat-induced blood clots and with those of both gray and white matter of the brain. Signal changes on T1-weighted MR images were predicted on the basis of altered T, values in vitro. Postoperative images were visually examined for the predicted changes. With the addition of Surgicel, blood had decreased pH and significantly shortened T1 at all fields, essentially within minutes, although it affected the T1 of saline only minimally. The effect of Surgicel increasingly shortened the T1 for 4 days in oxygenated blood. Collastat had no significant effect. The presence of some paramagnetic methemoglobin in Surgicel-induced clots was demonstrated using the relaxometer at a time when diamagnetic oxyhemoglobin would be present in naturally occurring blood clots. A bright signal that could mimic residual tumor on contrast-enhanced images was predicted and confirmed on postoperative T1-weighted MR images obtained in patients in whom Surgicel lined the tumor bed. It was not present in cases in which Surgicel was not used. CONCLUSIONS: Surgicel alters the appearance of early postoperative MR images. To avoid misinterpretation, clinicians should be aware of this phenomenon.

Giant petrous carotid aneurysm treated by submandibular carotid-saphenous vein bypass. Case report.

Petrous and cavernous sinus carotid artery (CA) aneurysms that are not amenable to clip ligation or endovascular therapy may be successfully treated by a saphenous vein bypass, thereby preserving the patency of the CA. The authors report the unique case of a 47-year-old man with a giant fusiform aneurysm of the petrous CA, who presented with a rapid onset of a lateral rectus palsy and diplopia. The lesion was treated by trapping the aneurysm and performing a saphenous vein bypass from the cervical to the intracranial CA. The saphenous vein graft was routed beneath the condyle of the mandible to reduce the overall length of the graft, thereby increasing the likelihood of long-term patency and offering protection to the graft by the mandible, temporal muscle zygomatic process, and masseter and temporal muscles. The presentation and technical aspects of the bypass graft in this unique case are discussed.

Reversal of radiographically impending stroke with multiple intraarterial papaverine infusions in severe diffuse cerebral vasospasm induced by subarachnoid hemorrhage.

BACKGROUND: Selective intraarterial infusion of papaverine is used in the treatment of symptomatic cerebral vasospasm induced by aneurysmal subarachnoid hemorrhage (SAH). Delays in instituting therapy for vasospasm can lead to irreversible cerebral infarction and a devastating outcome. Endovascular papaverine treatment of vasospasm in the presence of low-attenuation lesions on computed tomography (CT) is controversial, because of the fear of reperfusion hemorrhage in completed infarcts. METHOD: Two patients with aneurysmal SAH who subsequently developed severe diffuse vasospasm were identified. In both patients, large areas of low-attenuation change suggesting impending cerebral infarction were seen on CT scans. The patients received multiple infusions of intraarterial papaverine in an effort to treat vasospasm refractory to medical management. FINDINGS: After multiple intermittent administrations of papaverine, which initially appeared to increase the low-attenuation changes, there was dramatic reversal of the radiographic findings. There was also improvement in circulation time, transcranial Doppler velocities, and clinical outcome. INTERPRETATION: These findings suggest that in some patients, intraarterial infusions of papaverine initiated in the earliest stages of ischemia may exacerbate the radiographic appearance of low-attenuation changes, but may ultimately reverse the evolution of cerebral infarction.

Open-ring imaging sign: highly specific for atypical brain demyelination.

OBJECTIVE: To test the specificity for demyelination of a new neuroimaging sign: contrast enhancement shaped as an open ring or a crescent circumscribed to the white matter. BACKGROUND: Brain demyelination can cause ring enhancement mimicking neoplasm or infection on CT or MRI. METHODS: A MEDLINE search of pathology-proved demyelination yielded 32 illustrated cases of ring-enhancing lesions published between 1981 and 1995. Controls consisted of the same number of published images of neoplasms and infections, pathology proved, and matched by year of publication, and age and gender of the patient. Two neuroradiologists read the images twice independently 1 year apart. RESULTS: Interrater agreement was good (kappa = 0.64 and 0.66 for either reading). Test-retest reliability was high (kappa = 0.75 and 0.74 for either rater). The open-ring sign clearly distinguished demyelinating lesions from neoplasms and infections. For demyelination versus neoplasm or infection, the specificity of the reading by the first neuroradiologist was 93.8 (95% CI, 86 to 98), and that of the second was 84.4 (95% CI, 74 to 92). The likelihood ratio of demyelination versus neoplasm averaged 5.2, and versus infection, 17.2. That is, if the lesions had the same incidence in the population, in the presence of an open-ring sign demyelination would be five times more likely than neoplasm and 17 times more likely than infection. However, given the much higher incidence of neoplasms and infections, these lesions are still frequently responsible for open-ring enhancement. CONCLUSIONS: The open-ring sign is often present in large, contrast-enhancing demyelinating lesions and helps to differentiate them from neoplasms and infections.

Secretory and nonsecretory pituitary adenomas are distinguishable by 1/T1 magnetic relaxation rates at very low magnetic fields in vitro.

RATIONALE AND OBJECTIVES: The authors investigated whether hormonally active and inactive pituitary adenomas can be discriminated in vitro by magnetic resonance (MR) imaging-related data. METHODS: 1/T1 nuclear magnetic relaxation dispersion profiles were measured for 39 fresh surgical specimens of secreting and nonsecreting adenomas, classified using clinical criteria or preoperative serum hormone levels. Nonsecreting adenomas were subdivided into hormone-producing and nonhormone-producing by immunostains. At five fields (0.00024 to 1.2 tesla [T]), mean 1/T1 was analyzed for statistically significant differences among these three tumor categories. RESULTS: Mean 1/T1 was significantly higher (P < 0.02) for hormone-secreting than for nonsecreting adenomas at fields below 0.24 T; no significant difference existed at typical MR imaging fields (0.5 to 1.5 T). Mean 1/T1 for hormone-producing and nonhormone-producing, nonsecreting adenomas were not significantly different at any field. CONCLUSIONS: Because 1/T1 at low fields is related to 1/T2 at imaging fields, it may be possible to detect hormone secretion of pituitary adenomas noninvasively by MR imaging.

Calcification can shorten T2, but not T1, at magnetic resonance imaging fields. Results of a relaxometry study of calcified human meningiomas.

RATIONALE AND OBJECTIVES: Water content and water-proton relaxation rates are reported for fresh, histologically characterized, surgical specimens of calcified human intracranial meningiomas and compared with results for noncalcified meningiomas from an earlier study and with calcium hydroxyapatite (CaHA) suspensions to elucidate the influence of calcification on magnetic resonance imaging (MRI) signal intensity of calcified meningiomas. METHODS: The magnetic field dependence of 1/T1 of water protons (nuclear magnetic relaxation dispersion profile) and dry weights are reported for 38 calcified nonhemorrhagic and 3 hemorrhagic specimens of known histologic subtype, a subset of the 67 specimens measured earlier. Calcification was considered mild or heavy when the dry weight was within or above the range for noncalcified meningiomas. Preliminary 1/T1 profiles for pure CaHA and a single high-field 1/T2 value also are reported. RESULTS: The ranges of dry weights and of low-field 1/T1 values were twice as large for calcified as for noncalcified meningiomas. No correlation was found between low-field 1/T1 and either histologic subtype or dry weight. Mild calcification produced the highest low-field 1/T1 values; the most heavily calcified tumor had slightly increased low-field 1/T1. Calcium hydroxyapatite increases low-field 1/T1 significantly but not high-field 1/T1; high-field 1/T2 is large. For calcified hemorrhagic meningiomas, increases in both low-field and high-field 1/T1 were seen. CONCLUSION: For mild calcification, MRI signal voids result from an increased high-field 1/T2; for heavier calcification, reduced proton density (from excluded water) becomes of increasing importance. Cellular CaHA appears to brighten the signal in T1-weighted MRI in the presence of hemorrhage.

ACTH-producing pituitary carcinoma presenting as the cauda equina syndrome.

A 43-year-old woman presented with incontinence, weakness, and paresthesia, consistent with the cauda equina syndrome, 10 years after having a pituitary tumor surgically removed and 4 years after excision of two "meningiomas" of the cervical cord. The patient was also hypertensive and had a cushingoid habitus. Emergent surgical decompression of the spinal cord revealed intradural metastatic adrenocorticotropic hormone-producing pituitary carcinoma. Pituitary carcinomas are rare. The majority of reported cases of adrenocorticotropic hormone-producing carcinoma have exhibited metastases outside the central nervous system. To our knowledge, this represents the first case of an adrenocorticotropic hormone-producing pituitary carcinoma presenting with the cauda equina syndrome. A review of all reported cases of pituitary carcinoma indicated that central nervous system metastases were more common than metastases to distant sites, and patients with distant metastases experienced a shorter duration of disease than did those with central nervous system metastases.

Relaxometry of noncalcified human meningiomas. Correlation with histology and solids content.

RATIONALE AND OBJECTIVES: Resected meningiomas were examined by relaxometry and light microscopy to evaluate the potential of magnetic resonance imaging (MRI) for identifying histologic subtypes and for discriminating among benign, radiation therapy-induced, and malignant meningiomas. METHODS: The magnetic field dependence of 1/T1 of water protons (nuclear magnetic relaxation dispersion [NMRD] profile) and the water content (dry weight) were measured for 67 specimens, and the data were compared with histology. Only noncalcified, nonhemorrhagic meningiomas are reported. RESULTS: No correlations were found between NMRD profiles, dry weight, and any histologic subtype, in contrast to an analogous study of astrocytomas. Rather, meningiomas have a broader variability of dry weight and 1/T1 than related parenchyma but a much narrower range than all grades of astrocytomas. The mean value of 1/T1, at all fields, is slightly higher in meningiomas--and the mean water content about the same--as adult cortical gray matter. CONCLUSION: Meningiomas are frequently isointense with cortex, and histologic subtypes cannot be differentiated at any magnetic field strength by MRI using only T1- or proton density-weighted MRI.

Correlation of intracranial pressure and transcranial Doppler resistive index after head trauma.

PURPOSE: To investigate the usefulness of transcranial Doppler ultrasonography in the evaluation of intracranial pressure changes after head injury. METHODS: Transcranial Doppler examinations and intracranial pressure measurements using intraparenchymal monitors were performed in 12 cases of closed head injury. Twenty-four sets of data, including the Glasgow Coma Scale, intracranial pressure, transcranial Doppler, and carbon dioxide pressure were compared. The side-to-side difference in the resistivity index was also assessed. RESULTS: There was a significant correlation between increased pressure values and resistivity index when comparing measurements from the same side. There was no correlation between carbon dioxide pressure and any transcranial Doppler parameter or intracranial pressure measurement. No significant correlation was found between the resistivity index and the Glasgow Coma Scale. End diastolic velocity was a stronger determinant of resistivity index than peak systolic velocity. CONCLUSION: The relationship of ipsilateral measurements of intracranial pressure to resistivity index is valid. The resistivity index must be analyzed within the context of the particular disease studied, especially with respect to the hemodynamic alterations. Initial findings suggest that intracranial pressure monitoring cannot be replaced by serial transcranial Doppler measurements in the treatment of the patient with acute head injury.

Variation of the magnetic relaxation rate 1/T1 of water protons with magnetic field strength (NMRD profile) of untreated, non-calcified, human astrocytomas: correlation with histology and solids content.

The magnetic relaxation rate 1/T1 of tissue water protons was measured over a wide range of magnetic field strengths (NMRD profile) for 92 fresh surgical specimens of astrocytomas to search for correlations of 1/T1 with tumor histology, as determined by light microscopy, and to assess the diagnostic potential of NMRD profiles for grading astrocytomas. A third goal was to elucidate the molecular determinants of 1/T1. Each specimen was histologically graded and inspected for evidence of mineral deposits (Ca, Fe); its dry weight was determined and expressed in % of original wet weight. To minimize variability not directly related to tumor grade, this initial report is limited to NMRD profiles of 47 non-calcified, non-hemorrhagic, untreated astrocytomas. For these, the mean value of 1/T1 at very low magnetic field strengths was found to increase with increasing grade of malignancy; no clear correlation could be demonstrated at high fields where most imaging is done. The spread of 1/T1 for different grades of malignancy is large, however, and the overlap significant, even at the lowest field, so that astrocytomas can not be graded by NMRD profiles alone. Average 1/T1 and average dry weight increase with grade of malignancy; but the variability of 1/T1 among specimens of the same dry weight is large, indicating that at least one other cellular parameter, not variable in normal tissue, influences 1/T1 strongly. We hypothesize that this parameter reflects changes at the molecular level in size distribution, mobility, or intermolecular interaction of cytoplasmic proteins. Which specific changes are induced by malignant transformation in astrocytomas remains to be investigated.

Ventricular free wall and septal rupture (double rupture): a "pseudocomplication" during post-infarction laser angioplasty.

We report the rare occurrence of double rupture of the myocardium occurring immediately following successful laser recanalization of an occluded right coronary artery in a 72-year-old woman 5 days following infero-posterior myocardial infarction.

Cerebral blood flow velocity after head injury: transcranial Doppler evaluation. Work in progress.

To study blood flow velocity (BFV) changes, serial transcranial Doppler ultrasound (US) examinations of basal cerebral arteries were performed in 47 patients with head injury. Computed tomographic (CT) scans obtained at admission were analyzed for the presence of intracranial hemorrhages. Glasgow Coma Scale scores were obtained at admission in 46 patients. The prevalence of posttraumatic increased BFV was 77% (n = 36). Two groups of patients were identified according to the time of onset of increased BFV. They differed with respect to duration and severity of changes, Glasgow Coma Scale score, and evidence of intracranial hemorrhagic lesions. Low Glasgow Coma Scale scores were predictive of increased BFV within 72 hours after injury (P < .001). Patients with hemorrhages were significantly more prone to experience increased BFV within 72 hours (P < .05); 34% of patients who did not have hemorrhage, however, developed increased BFV. Increased BFV after head trauma is not uniformly found and cannot be explained by one pathologic mechanism.

A microsporidian previously undescribed in humans, infecting enterocytes and macrophages, and associated with diarrhea in an acquired immunodeficiency syndrome patient.

To date, the only microsporidian that has been associated with diarrhea and weight loss in acquired immunodeficiency syndrome patients is the newly identified Enterocytozoon bieneusi. A second species is now described that was associated with intestinal symptoms in a 32-year-old, human immunodeficiency virus- seropositive, Native American male homosexual. Stool studies and routine light microscopy of multiple small intestinal biopsies that showed atrophy with acute and chronic inflammation were without apparent pathogens. Light microscopy of semi-thin plastic sections, cytochemical stains of paraffin sections, and ultrastructural studies revealed extensive microsporidial infection of enterocytes and submucosal macrophages. No other pathogens were identified. Unlike E bieneusi, this microsporidian appeared to develop within septated parasitophorous vacuoles, and lacked polar disks and clear clefts. It most closely resembled, but was distinguishable from, members of the genus Encephalitozoon. Awareness of the microsporidia as potential opportunists in acquired immunodeficiency syndrome patients is increasing the incidence of identification of these organisms.

Localization of infection by the microsporidian Enterocytozoon bieneusi in the gastrointestinal tract of AIDS patients with diarrhea.

OBJECTIVE: We compared the level of Enterocytozoon bieneusi infection at different sites within the small intestine among patients with AIDS. DESIGN: The level of E. bieneusi infection of each patient biopsy was determined and compared using semi-thin plastic section light microscopy and transmission electron microscopy (TEM). PATIENTS, PARTICIPANTS: Nine subjects with chronic diarrhea who had endoscopic biopsies of either proximal (bulb) or distal (fourth portion) duodenum plus proximal jejunum (just past ligament of Treitz), either simultaneously or within a few months of each other were studied. All patients had TEM-confirmed diagnoses of E. bieneusi intestinal microsporidiosis. RESULTS: The intensity of infection was always greater in biopsies taken from the patients' jejunum compared with those taken from the duodenal bulb. In one patient, the duodenal bulb biopsy was negative while the jejunal biopsy, taken at the same time, was positive. The distal duodenum was usually, but not always, equal to the jejunum in terms of parasite burden. Esophageal, gastric, and colorectal biopsies from these and other patients were negative for E. bieneusi. CONCLUSIONS: For the diagnosis of E. bieneusi to evaluate chronic diarrhea in AIDS patients, upper intestinal endoscopy biopsies should be taken at the most distal site possible.