Derivation of Power M-Mode Transcranial Doppler Criteria for Angiographic Proven MCA Occlusion

BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies.     

Deficits in spatial coding and feature binding following damage to spatiotopic maps in the human pulvinar.

We report a patient with unilateral damage to the rostral part of the pulvinar who was impaired in localizing stimuli in the inferior visual field contralateral to the lesion and who made errors in the binding of shape and color in that quadrant. The findings demonstrate the importance of the pulvinar in spatial coding and provide support for the function of the thalamus in binding of features. They also provide evidence for a homology between the visual field maps of the inferior and lateral subdivisions of the pulvinar in monkeys and in humans, such that the inferior visual field is represented in the rostral part of the nucleus.     

Surgical treatment of spinal chordomas

The clinical features and results of 34 patients with chordomas treated over a seven-year period were analyzed. Surgical treatment consisted of wide local excision (n = 6), marginal resection (n = 5), intralesional resection (n = 20), and biopsy (n = 3). Eighteen patients received postoperative radiotherapy. The local recurrence rate was 65%, with 30% of patients developing distant metastases. With the introduction of computed tomography, smaller tumors are currently being diagnosed; as a result, 35% of the patients in this series are disease free, compared with 10% described previously.     

Pharmacokinetics of Nisoldipine Coat--Core Formulation in Subjects with Liver Cirrhosis

The pharmacokinetics of a controlled-release formulation (coat--core) of the calcium channel blocker nisoldipine was investigated in eight subjects with biopsy-proved liver cirrhosis and eight healthy subjects. In Stage I, subjects received a single 10-mg dose to determine if this dose would be safely tolerated in the subjects with cirrhosis. Because all subjects in both groups tolerated the dose without difficulty, all were continued to Stage II. In Stage II, subjects received a once-daily dose of 10-mg coat-core tablets for 7 days. Serial plasma samples were assayed for nisoldipine in both stages. The C(max) and AUC of nisoldipine were approximately fourfold to fivefold higher (p < 0.01) in subjects with cirrhosis as compared to healthy subjects; however, there was overlap in the range of pharmacokinetic parameters between the two groups. The accumulation factor following multiple dosing was similar in both groups. Results suggest that nisoldipine dose should be optimized by monitoring of a pharmacodynamic end point, such as effect on blood pressure. It is likely that dose requirements for patients with liver disease will be lower.     

Ipsilesional line bisection bias in patients with chronic parietal lesions

The current study investigated whether an ipsilesional bias in line bisection, a conventional measure for diagnosing hemispatial neglect, persists even in the absence of this syndrome in patients with chronic lesions restricted to posterior association cortex or dorsolateral prefrontal cortex. Both left and right hemisphere parietal lesions produced ipsilesional bisection errors, and to a comparable degree. Patients with lesions in frontal cortex, on the other hand, did not show a consistent bias. We conclude that chronic parietal lesions produce an ipsilesional bias in line bisection, even in the absence of other clinical signs of neglect, and that left hemisphere lesions can affect line bisection to the same degree as right hemisphere lesions.