Cranial computerized tomography and Marie's ataxia: a case report.

Cranial computerized tomography (CT) is an aid in the diagnosis of the spinocerebellar degenerations and may be used to define and categorize individual cases based on the extent and localization of atrophy. We discuss a case of Marie's ataxia and the cranial computerized tomographic appearance.

Body computerized tomography and the thymus.

Preoperative body computerized tomography (CT) should be of value in depicting the size, extent, and location(s) of the thymus in myasthenic patients undergoing thymectomy. To date, we have been unable to visualize the thymus in three patients with myasthenia gravis using body CT. However, in two nonmyasthenic patients, large thymomas were clearly delineated. Although application of this technique currently appears limited by the size, location, and density of the thymus and the resolution of the scanners, we feel that CT of the mediastinum is an indicated procedure in the evaluation of the patient before thymectomy, especially in those myasthenic patients with a high risk of thymoma.

Cranial CT appearance of acute multiple sclerosis.

In acute multiple sclerosis, cranial computerized tomography (CT) may show periventricular and deep white matter contrast-enhanced lesions that are easier to see using 8 mm rather than 13 mm cranial CT sections. Follow-up studies show that the lesions evolve either to areas of density similar to the surrounding white matter or to low-density lesions. We presume they represent foci of active demyelination with extravasation of iodine through an altered blood-brain barrier. Enhanced cranial CT studies may be helpful in diagnosing acute multiple sclerosis and in following the course of the white matter lesions.

Autosomal dominant spinocerebellar ataxia: locus heterogeneity in a Nebraska kindred.

SCA1 is an adult-onset autosomal dominant ataxia that is genetically linked to loci on chromosome 6p. A highly informative GT-repeat marker, D6S89, has been closely linked to the SCA1 locus in five large kindreds. We have used this marker to perform linkage analysis in a smaller autosomal dominant ataxia family consisting of five generations designated as the Nebraska kindred. This kindred includes 33 affected (12 living) and 40 first-generation at-risk individuals. We examined eight affected individuals; all had gait and limb ataxia. We analyzed the D6S89 locus by the polymerase chain reaction. Based on the analysis of 31 individuals from this kindred, we statistically excluded linkage to D6S89 for moderate-to-tight linkage (less than 11% recombination). These data clearly demonstrate genetic heterogeneity among the autosomal dominant ataxias. In addition, we obtained linkage data for HLA-A and SCA1 in this kindred. Comparison of HLA-A with D6S89 shows the latter marker to be more powerful. Use of D6S89 and other highly polymorphic markers in this region will greatly facilitate genetic classification of ataxias and make presymptomatic diagnosis of SCA1 feasible.

Neuropsychological test performance in patients with dominantly inherited spinocerebellar ataxia: relationship to ataxia severity.

To determine whether the cognitive status of patients with dominantly inherited spinocerebellar ataxia (DSCA) might be related to neurologic severity, we administered a comprehensive neuropsychological test battery to 43 patients with DSCA, ranging in ataxia severity from mild to end-stage. As compared with the controls, the mildly ataxic patients scored normally or close to normal as a group on all of the neuropsychological tests. In contrast, approximately one-half of the moderately and all of the severely ataxic patients showed poor performance, independent of age, Hamilton Rating Scale for Depression score, or education, on the Wisconsin Card Sorting Test, suggesting impaired executive system function. In addition, a subgroup of these patients had a neuropsychological profile suggestive of mild generalized cognitive impairment. We conclude that DSCA is not a homogeneous group of disorders with respect to cognitive status and that the neurologic severity of the disorder is a major factor. Impaired executive system function could be explained by damage to olivopontocerebellar system control over cerebral cortical function or to damage to other neuronal systems (especially cholinergic) that degenerate in parallel with the olivopontocerebellar system.

The paracentral visual field in multiple sclerosis: evidence for a deficit in interneuronal spatial summation?

A visual complaint such as blurred or "washed-out vision" can be one of the early signs of multiple sclerosis (MS). Although visual deficits are commonly attributed to optic nerve demyelination even with preserved visual acuity, the results of a considerable number of visual studies are inconsistent with this interpretation [Camisa, Mylin, & Bodis-Wollner, Annals of Neurology 10 (1981) 532-539; Regan & Neima, British Journal of Ophthalmology 68 (1984) 310-315]. However, a retinal axonal (nerve fiber layer) defect can be detected in some eyes, this is not the rule. Routine visual field (VF) tests, with a low sampling rate may also be non-informative in MS and optic neuritis, possibly because the VF abnormalities may be small and spotty or they can be found between tested points. The present study combined the advantages of VF and contrast sensitivity (CS) testing by applying contrast perimetry (CP), to the central 16 degrees of the VF. Four paracentral VF quadrants were tested in clinically affected and unaffected eyes of 31 MS patients and 26 controls. The stimuli were vertical Gaussian apertured sinusoidal gratings (Gabors) of 1 cpd. CS was obtained as a function of the diameter of the Gábor ranging from 1 to 7.4 degrees. The CP data of controls and definite and probable MS groups were significantly different for each pattern size, but the largest difference was found at diameters 2.5-3.7 degrees. Our study adds to previous evidence showing that optic nerve pathology does not explain "subclinical" and manifest visual dysfunction in MS. Given previous studies revealing orientation dependent monocular visual deficits and our study results, parsimony suggests that MS affects a network relying on myelinated lateral axonal branches of the visual cortex, binding monocular columns of neurons with like-with-like specificity.

Psychosurgery: a retrospective.

Of the 56 patients within the Yakovlev collection who had undergone psychosurgery 11 (20%) improved, 18 (32%) were either worse or without improvement, and 27 (48%) were without any clinical follow-up. Thus, in retrospect, psychosurgery was perhaps not as successful as once envisioned.