Faculty Bibliography

Prior studies on brain blood flow in chronic fatigue syndrome (CFS) did not find consistent results. This may be because they used single-photon emission computed tomography to measure brain blood flow, which could not measure absolute blood flow. Therefore, the aim of this study was to test the hypothesis that patients with CFS have reduced absolute cerebral blood flow. Xenon-computed tomography blood flow studies were done on 25 CFS patients and seven healthy controls. Analyses were done after stratifying the CFS patients based on the presence or absence of a current psychiatric disorder. Flow was diminished in both groups as follows: patients with no current psychiatric disorders had reduced cortical blood flow in the distribution of both right and left middle cerebral arteries (P<0.05 for both) while those with current psychiatric disorders had reduced blood flow only in the left middle cerebral artery territory (P<0.05). These data indicate that patients with CFS have reduced absolute cortical blood flow in rather broad areas when compared with data from healthy controls and that those devoid of psychopathology had the most reductions in cortical flow. These data support, in part, our earlier findings that patients devoid of psychopathology are the group most at risk of having some of the symptoms of CFS due to brain dysfunction.

A 57-year-old woman developed blindness during treatment for sarcoidosis-induced end-stage renal disease. An initial renal transplantation failed, and hemoaccess was maintained with multiple central catheters and upper extremity prosthetic arteriovenous grafts. A successful second transplantation eliminated her need for hemodialysis, but a right brachial to internal jugular graft remained patent. Progressive visual loss 2 years after transplantation prompted ophthalmic evaluation which initially revealed unilateral left optic nerve edema and visual loss, ultimately worsening over several months to no light perception in the left eye, 20/60 vision in the right eye, and bilateral papilledema. Arteriography demonstrated cerebral venous hypertension attributed to the functioning hemoaccess graft. Permanent graft occlusion normalized the papilledema, and visual field defects in the right eye and visual acuity returned to 20/20 in the right eye.

Recent advances in endovascular interventional therapies have revolutionized the management of acute ischemic stroke. For patients who present with occluded circle of Willis vessels, timely and successful arterial recanalization is the best predictor of clinical improvement. Diagnostic neuroimaging has advanced noninvasive tools--namely, transcranial Doppler, CT angiography, and MR angiography--to screen individuals with acute neurologic syndromes rapidly for arterial occlusion, and hence to exclude from treatment those who are unlikely to benefit from or could be harmed by arterial recanalization strategies. Intra-arterial thrombolysis has been proven to be of benefit in large clinical trials. Moreover, the US Food and Drug Administration has recently approved the use of a mechanical clot retrieval device for acute embolic stroke, and a number of other similar strategies are under various stages of investigation. This article reviews the diagnostic and interventional approach to the management of large vessel embolic stroke.

BACKGROUND AND PURPOSE: To summarize the prevalence of particular protocols used for routine magnetic resonance imaging of the cervical spine. METHODS: Centers nationwide were asked to submit routine protocols for degenerative disease. Cases with a history of demyelinating disease or suspected cord lesions were excluded. The pulse sequences and scanning planes were tabulated for 105 centers. For the last 53 centers studied, axial gradient recalled echo sequences were subdivided into 2-dimensional and 3-dimensional Fourier transform. RESULTS: There were 21 different combinations. A protocol consisting of sagittal T1+sagittal T2+axial gradient recalled echo T2 was used by 48% of centers. Two sagittal and 2 axial series in any combination was used in 30% (32/105 centers). One center used gradient recalled echo images exclusively, consisting of T1, proton density, and T2-weighted images, which included axial and sagittal planes. CONCLUSION: Sagittal T1+sagittal T2+axial gradient recalled echo T2 is by far the most prevalent protocol used for imaging the cervical spine.

With the approval of intravenous recombinant tissue plasminogen activator (r-TPA) in 1995, acute ischemic stroke therapy is increasingly being administered. Currently the approach to imaging these patients is very simplistic. Typically, noncontrast head computed tomography (CT) is the only study performed prior to treatment. Advanced imaging using CT or magnetic resonance imaging (MRI) can play a very important role in the triage and classification of patients with acute ischemic stroke. With knowledge of the location and size of the occlusion as well as the collateral circulation, the best treatment can be selected, minimizing any morbidity from treatment and maximizing the chance of success. The identification and stratification of patients according to their imaging and clinical features will further individualize treatment and allow tailored therapy. This review will discuss rapid imaging techniques that are easily available and the rationale for their use.

We describe a case of an actively bleeding aneurysm demonstrated by CT angiography (CTA). The active hemorrhage was characterized by a nebulous attenuation in the subarachnoid space adjacent to the aneurysm. The measurements (HU) of the hemorrhage were equal to or slightly less than those of the contrast material in the arteries and diminished as one moved further from the aneurysm. As CTA is used more frequently in the diagnosis of cerebral aneurysms, it is important to understand imaging features of this potentially lethal condition.

Spontaneous non-aneurysmal subarachnoid hemorrhage (SAH) centered in the quadrigeminal cistern has been proposed as a variant of perimesencephalic non-aneurysmal SAH (PNSH). Some authors contest the existence of this entity, claiming it results either from head trauma or an undiscovered P2-P3 aneurysm, and conclude that all PNSH arise in front of the brainstem in a 'pretruncal' location. We report a patient with a quadrigeminal pattern of subarachnoid blood who was investigated with two digital catheter angiograms, including 3-D angiography, plus a high-resolution computed tomography angiogram. No abnormal findings were present and the patient had an excellent outcome. We propose that the more common pretruncal PNSH and less common quadrigeminal PNSH are two types of perimesencephalic SAH with separate, distinct etiologies, both of which have a more benign clinical course than aneurysmal SAH.

BACKGROUND AND PURPOSE: In CT angiographic and perfusion imaging (CTA/CTP), rapid CT scanning is performed during the brief steady state administration of a contrast bolus, creating both vascular phase images of the major intracranial vessels and perfused blood volume-weighted parenchymal phase images of the entire brain. We assessed the added clinical value of the data provided by CTA/CTP over that of clinical examination and noncontrast CT (NCCT) alone. METHODS: NCCT and CTA/CTP imaging was performed in 40 patients presenting with an acute stroke. Short clinical vignettes were retrospectively prepared. After concurrent review of the vignettes and NCCT, a stroke neurologist rated infarct location, vascular territory, vessel(s) occluded, and Trial of Org 10172 in Acute Stroke Treatment (TOAST) and Oxfordshire Community Stroke Project classifications. The ratings were repeated after serial review of each of the CTA/CTP components: (1) axial CTA source images; (2) CTP whole brain blood volume-weighted source images; and (3) maximum-intensity projection 3-dimensional reformatted images. The sequential ratings for each case were compared with the final discharge assessment. RESULTS: Compared with the initial review after NCCT, CTA/CTP improved the overall accuracy of infarct localization (P<0.001), vascular territory determination (P=0.003), vessel occlusion identification (P<0.001), TOAST classification (P=0.039), and Oxfordshire Community Stroke Project classification (P<0.001) by 40%, 28%, 38%, 18%, and 32%, respectively. CONCLUSIONS: Admission CTA/CTP imaging significantly improves accuracy, over that of initial clinical assessment and NCCT imaging alone, in the determination of infarct localization, site of vascular occlusion, and Oxfordshire classification in acute stroke patients.