Adjusting the polymerization time of isobutyl-2 cyanoacrylate.

Isobutyl-2 cyanoacrylate (IBCA) polymerizes by an anionic mechanism. The initiation of polymerization depends on an alkaline medium and can be inhibited with the addition of small amounts of acid. Using small amounts of glacial acetic acid (3.7%-7.1% by volume), the polymerization time was prolonged from 2.3 sec to 7.8 sec. In vivo experiments in dogs demonstrated no additional inflammatory reactions to the mixture of IBCA, iophendylate, and tantalum powder when acetic acid was added. Glacial acetic acid offers a safe and effective way, without increase in viscosity, to manipulate the polymerization time of IBCA.

An unusual type of hangman's fracture.

An unusual fracture of the axis was best displayed using three-dimensional reconstruction. The fracture was noted to differ significantly from the usual "hangman's fracture" as it involved the body of C2 with subluxation of the anterior part of C2 forward on C3 and without "decompression" of the spinal canal at the C2 level. Better understanding made feasible by three-dimensional reconstruction had important treatment implications in this case.

Symptomatic arterial luminal narrowing presenting months after subarachnoid hemorrhage and aneurysm clipping.

The authors describe three cases of clinical cerebral ischemia associated with angiographic evidence of cerebral arterial luminal narrowing presenting 7, 14, and 52 weeks after subarachnoid hemorrhage (SAH) and aneurysm clipping. Delayed vasospasm, in its usual time setting 1 or 2 weeks after hemorrhage, did not occur symptomatically in these patients. No evidence for aneurysm clip migration or rebleed was present. All patients responded favorably to volume expansion and elevation of blood pressure. This unusual occurrence of a very delayed vasospasm may further the understanding of the vasospastic process. The symptomatic onset of arterial luminal narrowing months after SAH may suggest that a proliferative vasculopathy more accurately explains the observed vessel narrowing, rather than conventional active constriction of vascular smooth muscle.

Cerebral arteriovenous malformations with associated arterial aneurysms: hemodynamic and therapeutic considerations.

The common vascular anomalies of cerebral aneurysm and arteriovenous malformation may exist independently, or together as part of a closely related hemodynamic pairing. Resection or embolization of an AVM may be followed by a decrease in local blood flow, and lead to regression of a suitably situated proximal aneurysm. However, aneurysms located outside the angioarchitecture of the AVM, which remain flow-unrelated to the malformation, will likely not regress, and may in fact enlarge. Two cases are presented which demonstrate these vascular relationships, in order to better understand the regional hemodynamics of these anomalies prior to surgical or endovascular treatment planning.

Radiographic demonstration of a toxic agent.

The abdominal radiographs obtained on a young man attempting suicide by stabbing revealed an unusual opacity in the true pelvis, confirmed as being due to unsuspected carbon tetrachloride ingestion. This is the first known radiologic demonstration of oral ingestion of a rapidly acting toxic substance.

Increased density of tentorium and falx: a false positive CT sign of subarachnoid hemorrhage.

Noncontrast computed tomographic (CT) findings in 10 patients with profound brain swelling or a mass effect revealed a high density of the falx and tentorium and thus suggested subarachnoid hemorrhage. Postmortem examinations performed shortly after the CT scans demonstrated no subarachnoid blood. A review of 100 CT scans drawn at random was carried out to assess the frequency of a hyperdense, noncalcified falx in the same population and failed to demonstrate this finding. Therefore, in the presence of profound brain swelling or a mass effect, factors other than subarachnoid hemorrhage may be responsible for increased density of the falx and tentorium on cranial CT head scans.

CT of multiple sclerosis: reassessment of delayed scanning with high doses of contrast material.

A prospective study involving 87 patients was carried out to evaluate the necessity for a high dose of contrast material in addition to delayed computed tomographic (CT) scanning for optimal detection of the lesions of multiple sclerosis in the brain. In patients with either clinically definite multiple sclerosis or laboratory-supported definite multiple sclerosis, CT scans were obtained with a uniform protocol. Lesions consistent with multiple sclerosis were demonstrated on the second scan in 54 patients. In 36 of these 54 patients, the high-dose delayed scan added information. These results are quite similar to those of a previous study from this institution using different patients, in whom the second scan was obtained immediately after the bolus injection of contrast material containing 40 g of organically bound iodine. The lack of real difference in the results of the two studies indicates that the increased dose, not just the delay in scanning, is necessary for a proper study.