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Fifteen patients with right hemispheric subcortical infarcts localized by CT or MRI were evaluated with a neglect testing battery. Trimodal extinction was present in one case, visual extinction in three, tactile in three, and auditory in six. Although frequent (10 cases), hemispatial neglect was rarely severe (3 cases). Three cases recovered completely. Large posterior internal capsule lesions were associated with more frequent impairment on a cancellation test. The probable mechanism of hemispatial neglect was attentional in one case and intentional in six. Visual and auditory extinction is explained by striatonigral mechanisms. Although subcortical structures participate in attentional and intentional behavior, cortical structures can substitute for their functions.

Magnetic resonance imaging hyper-intensities were classified as periventricular rim, caps, and unidentified bright objects (UBOs). These were quantitated in 100 acute stroke and 23 hemorrhage patients and 59 control subjects selected from 590 consecutive scans. The rims, caps, and ventricular size were rated on a scale from 0 to 3 for severity, and the UBOs were counted. The results indicated that the rim is also frequent in control subjects and increases with age. Unidentified bright objects, caps, and severe rims usually signify pathology, occurring much more frequently in patients with strokes and hemorrhages than in control subjects. Hypertension is a significant risk factor in UBOs and caps, but in rims, the incidence of diabetes is higher. The clinical and pathologic significance of these hyperintensities and their relationship to Binswanger's disease, lacunar state, and "état criblé" is discussed.

We describe the clinical characteristics and a series of magnetic resonance imaging (MRI) studies in a patient with the features of dorsal midbrain syndrome occurring in the setting of multiple sclerosis. A T2-weighted MRI study revealed a discrete abnormality in the tectum of the midbrain whereas a high volume delayed computed tomography (CT) scan was uninformative. In parallel with remission of the clinical findings, the MRI abnormality diminished over time and was no longer visible at one year suggesting that some MRI detected MS lesions can completely disappear with time. This report demonstrates the use of MRI to detect and to follow sequentially sites of known disease activity in MS.

Magnetic Resonance Imaging (MRI) reveals anatomical asymmetries of the sulcal demarcation of the posterior operculum from the parietal cortex that correlate with handedness in normal subjects. The sulcal demarcation is greater on the right in most right handers, but evenly distributed in left handers. This in vivo asymmetry corresponds to the commonly larger planum temporale on the left side. Hand Preference, Hand Performance, Dichotic Listening and Visual Field Preference measures were correlated with several measures of anatomical asymmetries seen on MRI. The sulcal demarcation, anterior frontal width and parietal width correlated best with hand performance, as measured on a dot tapping task. The biological significance of the distribution of anatomical and functional asymmetries is discussed.

We compared MRI and CT in a study of 175 patients; 87 infarcts within a week, 40 from 1 to 40 weeks, 25 a year after onset, and 23 hemorrhages, 18 within 2 weeks and 5 in 4 to 8 weeks. Fifty-nine infarcts and eight hemorrhages had sequential scanning. MRI is more sensitive than CT in the early detection of cerebral infarcts. CT is the method of choice to rule out intracerebral bleeding, but MRI is more specific in later stages of hemorrhage. Periventricular hyperintensity is seen more frequently with diabetes than without. Hyperintense white matter patches are often unrelated to clinical events. MRI is useful in following the evolution of strokes and distinguishing acute and chronic infarcts without contrast agents.

We studied motor impersistence with a standardized clinical test of sustained actions, both in patients with acute focal stroke lesions, who were matched for age and size of lesion, and normal controls. Patients with right-sided lesions had significantly more impersistence than did those with left-sided lesions. The most discriminating tests were eye-closure, mouth-opening, tongue-protrusion, and gaze to the left. Right central and frontal lesions seemed to be more responsible for motor impersistence than were posterior or left-sided lesions. Although motor impersistence is sometimes seen with diffuse cerebral disease, it is also a sign of right-hemisphere lesions; the phenomenon is probably related to mechanisms of directed attention that are necessary to sustain motor activity.

To investigate the neural generators of the subcortical somatosensory evoked potential (SEP) waves we studied the far-field SEPs in 20 normal adults. We stimulated the median nerve at the wrist and used a 40k gain, 25 msec sweep and a 150-3000 Hz bandpass. We recorded SEPs simultaneously over C3' and C4' using a non-cephalic clavicle reference. The following series of six positive waves were found reliably in all subjects: P9, P11, P13, P14, P16 and P17. The P16 and P17 probably arise from the thalamus and/or thalamocortical projections. Recent evidence suggests that the thalamus is not a closed field and thus one should be able to find corresponding waveforms in far-field recordings. We believe that this is a function of the bandpass used and with the above paradigm these components can be reliably recorded. We found significant ipsilateral and contralateral amplitude asymmetries beginning with the negative deflection after P14 and including P16 and P17. The amplitude was greater over the contralateral hemisphere. This suggested that both P13 and P14 are generated prior to decussation of the afferent fibres in the medial lemniscus. Bilateral recording allowed detection of this asymmetry which has not been previously reported as a means of determining the electrophysiological correlates of lateralization.