Behavioral and neurophysiological correlates of episodic coding, proactive interference, and list length effects in a running span verbal working memory task.

Updating refers to (1) discarding items from, (2) repositioning items in, and (3) adding items to a running working memory span. Our behavioral and fMRI experiments varied three factors: trial length, proactive interference (PI), and group integrity. Group integrity reflected whether the grouping of items at the encoding stage was violated at discarding. Behavioral results were consistent with the idea that updating processes have a relatively short refractory period and may not fatigue, and they revealed that episodic information about group context is encoded automatically in working memory stimulus representations. The fMRI results did not show evidence that updating requirements in a task recruit executive control processes other than those supporting performance on nonupdating trials. They did reveal an item-accumulation effect, in which signal increased monotonically with the number of items presented during the trial, despite the insensitivity of behavioral measures to this factor. Behavioral and fMRI correlates of PI extended previous results and rejected an alternative explanation of PI effects in working memory.

Use of three-dimensional Guglielmi detachable coils in the treatment of wide-necked cerebral aneurysms.

A three-dimensional Guglielmi detachable coil (3D-GDC) has been developed that is designed specifically to bridge the neck of an aneurysm with coil loops, thereby facilitating retention of additional coils placed within the aneurysm. Nine wide-necked cerebral aneurysms were successfully embolized using the 3D-GDC, provided that the dome-to-neck ratio was 1.5 or greater.

Angiographic correlation of CT calcification in the carotid siphon.

BACKGROUND AND PURPOSE: Calcification in the coronary arteries has been correlated with significant vessel stenosis. The predictive value of calcification within the carotid siphon has not been characterized; however, stenosis in the carotid siphon is potentially important in determining management of patients with ipsilateral carotid bifurcation stenosis. The purpose of this study was to determine optimal parameters for assessing carotid siphon calcification on head CT scans and to compare the CT findings with angiographic results. METHODS: We performed a retrospective review of patients referred for diagnostic carotid arteriography. Those patients who also had undergone a head CT study at our institution were selected. The CT scans and angiograms of 64 patients (128 vessels) were reviewed. Carotid siphon calcification on CT scans was characterized on brain and bone windows as mild, moderate, or severe. Comparison was then made with angiographic findings. RESULTS: The sensitivity and specificity of CT for depicting greater than 50% angiographic stenosis in the carotid siphon were 86% and 98%, respectively, for bone windows and 100% and 0%, respectively, for brain windows. The positive predictive value (PPV) for a stenosis of greater than 50% as evidenced by severe calcification was 86% on bone windows and 11% on brain windows. The PPV for mild and moderate calcification on bone windows was 2.5% and 0%, respectively. CONCLUSION: Severe CT calcification in the carotid siphon as characterized on bone windows correlates with a carotid siphon stenosis of greater than 50% as determined angiographically. Therefore, the identification of severe calcification offers a potential noninvasive method for identifying stenosis of the carotid siphon. This information may be essential in determining management and prognosis for patients with carotid bifurcation stenosis.

Complete duplication or extreme fenestration of the basilar artery.

We describe a 42-year-old man with complete duplication or extreme fenestration of the basilar artery. We review the developmental anatomy and embryology and discuss the possible clinical implications and associated findings of this anomaly.

Assessment of the value of MR imaging for examining patients with angiographically negative subarachnoid hemorrhage.

OBJECTIVE: Our goal was to assess the value of MR imaging to patient care in the setting of angiographically negative subarachnoid hemorrhage and to evaluate the potential of MR imaging for revealing the mechanism for idiopathic perimesencephalic subarachnoid hemorrhage. MATERIALS AND METHODS: We retrospectively reviewed 71 patients who presented with subarachnoid hemorrhage and in whom the results of a four-vessel cerebral arteriogram were negative, a CT scan showed no evidence of intraaxial hemorrhage, and MR imaging had been performed within 72 hr of presentation. MR imaging of the brain included sagittal spin-echo T1-weighted, turbo spin-echo proton density-weighted, T2-weighted, and axial T2-weighted gradient-echo sequences. MR imaging of the cervical spine, which was performed in 41 of the 71 patients, included sagittal spin-echo T1-weighted, turbo spin-echo proton density-weighted, T2-weighted, and axial T2-weighted gradient-echo sequences. RESULTS: Perimesencephalic subarachnoid hemorrhage was seen on CT in 25 patients; in four of these patients (16%), MR imaging revealed acute perforator territory infarction involving the caudate, putamen, or thalamus. In 26 other patients, nonperimesencephalic subarachnoid hemorrhage was revealed on CT; in two of these patients (8%), MR imaging showed the cause of the subarachnoid hemorrhage. By contrast, 20 patients had negative findings on CT scans but xanthochromic CSF on lumbar puncture; in two of these patients (10%), MR findings were interpreted as responsible for subarachnoid hemorrhage. CONCLUSION: MR imaging showed diagnostic value in patients with angiographically negative subarachnoid hemorrhage, revealing abnormalities in 14% of the 71 patients, and resulted in a significant change in patient treatment in 6% of the patients. MR imaging also revealed an association between perimesencephalic subarachnoid hemorrhage and infarcts involving the territory of perforating arteries at the base of the brain. This finding may provide insight into the pathogenesis of perimesencephalic subarachnoid hemorrhage.

CT-guided percutaneous drainage of syringomyelia.

PURPOSE: Our purpose is to describe CT-guided percutaneous drainage of syringomyelia as a possible contribution in patient management. METHOD: CT-guided percutaneous drainage was performed on three patients with symptomatic syringomyelia. We determined the success of percutaneous decompression by subsequent CT and MRI. The effect of syringomyelia decompression in relation to the patient's symptoms was determined. This information was then used to help guide clinical management. RESULTS: In Case 1, percutaneous drainage of a large syrinx in a C5 quadriplegic patient with increasing lower extremity spasticity demonstrated significant decompression by imaging but did not result in clinical improvement. A surgical procedure to decompress the syrinx was not performed on the basis of this information. In Case 2, percutaneous drainage of a large syrinx in a quadriplegic patient with increasing upper extremity numbness and weakness demonstrated significant decompression by imaging and resulted in sustained clinical improvement, temporarily obviating the need for surgery. In Case 3, percutaneous drainage of the rostral aspect of a septated syrinx cavity in a patient with a Chiari I malformation and a syringoperitoneal shunt in place resulted in decompression by imaging but failed to relieve the patient's newly developed symptoms. An additional shunt was therefore not placed. In no case did the patient experience periprocedural complications or worsening of symptoms. CONCLUSION: CT-guided percutaneous drainage of syringomyelia is a safe and successful technique. It can be used diagnostically to identify patients that may or may not benefit from surgical syrinx decompression and in some cases may provide a temporary therapeutic alternative to surgery.

Brown-Séquard syndrome of the cervical spinal cord after chiropractic manipulation.

We report a case of increased signal in the left hemicord at the C4 level on T2-weighted MR images after chiropractic manipulation, consistent with contusion. The patient displayed clinical features of Brown-Séquard syndrome, which stabilized with immobilization and steroids. Follow-up imaging showed decreased cord swelling with persistent increased signal. After physical therapy, the patient regained strength on the left side, with residual decreased sensation to pain involving the right arm.

Current indications and techniques in evaluating inflammatory disease and neoplasia of the sinonasal cavities.

Imaging strategies of the sinonasal cavities have undergone extensive revision over the last 5-year period. The traditional imaging examination of the paranasal sinuses, plain film radiography, does reasonably well in diagnosing maxillary, frontal, and sphenoid sinusitis. However, it less reliable in depicting abnormalities in the ethmoid sinuses, the most common area first affected with inflammatory disease. Compared with sinus computed tomography (CT), plain films prove to be less specific and sensitive in depicting the extent of sinus abnormalities. One series plainly concluded that sinus radiographs were not reliable enough to be an integral part of the clinical decision process. The use of plain radiographs of the sinuses has clearly been reduced by medical cost-containment concerns, replacement by superior techniques, and by clear weaknesses of the modality. Although it is inexpensive and easily accessible, the low sensitivities and inaccuracies of plain film radiography have resulted in the current use of CT and high-field-strength (1.5 Tesla) magnetic resonance imaging (MRI). By using this cross-sectional imaging, we now visualize directly the pathologic conditions within the sinuses, as well as the normal anatomy. We discuss current use of diagnostic imaging in the evaluation of patients with nasosinusoidal complaints (most commonly resulting from acute and chronic inflammatory disease), with complications of sinonasal inflammatory disease, and with suspected/documented neoplasia. In addition to developing an imaging algorithm to provide the information affecting clinical decision making, we detail the specific imaging techniques necessary accurately to obtain that information. We also review the specific concerns about imaging patients in the intensive care unit and touch on several emerging imaging techniques. The imaging workup in pediatric patients and patients with congenital anomalies is beyond the scope of this review.

Prevalence of cerebral aneurysms in patients with fibromuscular dysplasia: a reassessment.

OBJECT: The aim of this study was to determine the prevalence of cerebral saccular aneurysms in patients with carotid artery and/or vertebral artery (VA) fibromuscular dysplasia (FMD). METHODS: A metaanalysis was performed using data from 17 previously reported series of patients with internal carotid artery (ICA) and/or VA FMD that included information on the prevalence of cerebral aneurysms. In addition, the authors retrospectively evaluated their own series of 117 patients with ICA and/or VA FMD to determine the prevalence of cerebral aneurysms. The metaanalysis of the 17 earlier series, which included 498 patients, showed a 7.6 +/- 2.5% prevalence of incidental, asymptomatic aneurysms in patients with ICA and/or VA FMD. In the authors' series of patients with FMD, 6.3 +/- 4.9% of patients harbored an incidental, asymptomatic aneurysm. When the authors' series was combined with those included in the metaanalysis, the prevalence was found to be 7.3 +/- 2.2%. The prevalence of aneurysms in the general population would have to be greater than 5.6% for there to be no statistically significant difference (chi-square test, p < 0.05) when compared with this 7.3% prevalence in patients with FMD. CONCLUSIONS: The prevalence of intracranial aneurysms in patients with cervical ICA and/or VA FMD is approximately 7%, which is not nearly as high as the 21 to 51% prevalence that has been previously reported.

Lincoln's vertical strabismus.

BACKGROUND: The vertical strabismus manifested by Abraham Lincoln has been noted. This article reviews the historical findings and provides a specific diagnosis. MATERIALS: Previous reports of symptoms and history relating to Lincoln's left hypertropia were reviewed. A series of photographs were reviewed. Lincoln's own description of his symptoms is provided. RESULTS: Previous history indicates an intermittent left hypertropia. A family history of vertical strabismus was noted with regard to Mr Lincoln's cousin. There also is a history of trauma to the left frontal area and life-mask evidence of fracture over the left eye. The findings include a history of head tilt and diplopia, presumably most readily in downgaze. CONCLUSION: Given the history and findings, the diagnosis of left superior oblique paresis of either congenital or traumatic origin seems appropriate.

Atropine versus cyclopentolate plus tropicamide in esodeviations.

BACKGROUND AND OBJECTIVE: The correction of the total hypermetropic refractive error in the management of esodeviations is well accepted. The choice of the appropriate cycloplegic agent is still not settled. Despite evidence that atropine will more effectively uncover the total refractive error, cyclopentolate in combination with other cycloplegic agents continues to be recommended. This study evaluates the use of atropine compared with a combination of cyclopentolate and tropicamide and analyzes age, size of the refractive error, and size of the esodeviation as possible contributing variables in the response. PATIENTS AND METHODS: The records of 74 patients who underwent refraction with atropine 1% on one occasion and a combination of 1% cyclopentolate and 1% tropicamide on another occasion were reviewed. The mean and range of refractive errors for each eye for each group were determined. Comparisons were made for groups depending on age, size of the refractive error, and size of the esodeviation. RESULTS: The amount of hypermetropia determined with atropine was significantly higher than the amount determined with the combination of cyclopentolate and tropicamide. This difference was significant for three age groups of three groups with increasing amounts of hypermetropia, and two groups with differing amounts of esodeviations. In addition, 11% of right eyes and 19% of left eyes showed 1.25 D or more of hypermetropia with atropine. CONCLUSION: Refraction with 1% atropine ointment yields a significantly larger amount of hypermetropia than does refraction with a combination of cyclopentolate and tropicamide. This difference is statistically significant regardless of age, amount of hypermetropia, or size of the esotropia.

Spasm of the near reflex: a spectrum of anomalies.

Spasm of the near reflex has been characterized as the variable appearance of pseudomyopia, convergent strabismus and miosis. These characteristics may appear together or separately. In addition, abnormalities of accommodation may appear not only as pseudomyopia, but may also be manifest in cases with significant hypermetropia in which the patient is unable to relax accommodation even when plus lenses are used. The intent of this review is to identify the various clinical presentations of anomalies of the entire near reflex as well as the component parts. The relationship to functional and organic disorders are discussed as well as the related neuroanatomy. We suggest that one may more readily understand the clinical manifestations as a spectrum of anomalies of the near reflex rather than a multitude of disconnected entities.

The reliability of adjustment in strabismus surgery.

It has been recommended that the position of the operated muscles be adjusted shortly after strabismus surgery to achieve better alignment on the first postoperative day and thereby ensure satisfactory later alignment. We compared prism cover test measurements on the first postoperative day with measurements within the first few months after surgery to determine whether day 1 measurements remained stable or whether they changed significantly, providing an inaccurate basis for adjustment. Our study found a fairly large variability in the deviation between the first and last day of the study. Eighteen percent of patients varied by 5 to 9D, and 49% differed by > 10D or more. Equally important was the finding that, had an adjustment been made, it would have made the final result worse than without adjustment. Both of these factors would seem to indicate a degree of variability that controverts the predictability of the adjustment procedure.

Efficacy of supine versus prone biliary lithotripsy: an in vitro study.

Clinical extracorporeal shock wave lithotripsy (ESWL) results have shown that the smaller the gallstone fragments following ESWL, the faster the patient will become stone-free. At ESWL, an attempt is made to produce sand-like fragments that will easily pass through the cystic and common bile ducts. Sixteen pairs of gallstones of equal shape, size, and composition were harvested from cholecystectomy specimens and then fragmented on the Dornier MPL-9000 lithotripter (Dornier Medical Systems, Inc.), individually, in a phantom oriented to duplicate either supine or prone patient positions. The number and size of remaining fragments were compared following the supine versus prone treatments. The 32 stones, ranging from 5-15 mm in diameter, received 1,500 shock waves at 21 kV. Fragments with a maximal diameter of greater than or equal to 4 mm were measured and counted after 750 and 1,500 shock waves. Fragments greater than or equal to 4 mm were found in four out of 16 stones treated supine (25%) and 16 out of 16 stones treated prone (100%). The largest residual fragment regardless of size for each stone pair occurred in the prone group in 14 out of 16 cases (88%). Biliary lithotripsy performed with supine positioning results in more efficacious gallstone fragmentation in this in vitro model; these findings suggest that supine positioning for patients could improve fragmentation and treatment success.