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Biomedical subjects

A L Foundas

Publications and source records attributed to A L Foundas.

At least 19 recordsLinked to original sources
PubMed1998

MRI asymmetries of Broca's area: the pars triangularis and pars opercularis.

Broca's area, which includes the pars triangularis (PTR) and pars opercularis (POP), is a neuroanatomic region important in speech-language production. Previous data demonstrated that PTR asymmetries are highly correlated with language dominance determined by selective hemispheric anesthesia or Wada testing, suggesting that asymmetries of the PTR may, in part, predict language dominance. The POP, however, has not been measured on volumetric magnetic resonance imaging (MRI), and therefore, it is unclear whether morphological asymmetries of the POP exist, and whether these asymmetries differ in right- and left-handers. The purpose of this study was to determine if measurable asymmetries of the POP exist on MRI, and whether the direction of the asymmetries differ in right- and left-handers. The PTR and POP were measured on volumetric MRI scans of 16 right-handers and 16 left-handers matched for age and gender. There was a significant leftward asymmetry of the PTR in right- and left-handers, although the asymmetry was reduced in the left-handers. In contrast, there was a leftward asymmetry of the POP in right-handers, and a rightward asymmetry in the left-handers. Handedness, derived from a handedness inventory, was positively correlated with POP asymmetry.

Adult↗
PubMed1998

Aspiration in patients with acute stroke.

OBJECTIVES: To determine the frequency and clinical predictors of aspiration within 5 days of acute stroke. DESIGN: Case series. SETTING: Tertiary care center. PATIENTS: Consecutive stroke patients (n = 55) with new neurologic deficit evaluated within 5 days of acute stroke. MAIN OUTCOME MEASURES: Comparison of features identified on clinical swallowing and oromotor examinations and occurrence of aspiration (silent or overt) evident on videofluoroscopic swallow study (VSS). RESULTS: Aspiration occurred in 21 of 55 patients (38%). Whereas 7 of 21 patients (33%) aspirated overtly, 14 (67%) aspirated silently on VSS. Chi-square analyses revealed that dysphonia, dysarthria, abnormal gag reflex, abnormal volitional cough, cough after swallow, and voice change after swallow were significantly related to aspiration and were predictors of the subset of patients with silent aspiration. Logistic regression revealed that abnormal volitional cough and cough with swallow, in conjunction, predicted aspiration with 78% accuracy. CONCLUSIONS: Silent aspiration appears to be a significant problem in acute stroke patients because silent aspiration occurred in two thirds of the patients who aspirated. The prediction of patients at risk for aspiration was significantly improved by the presence of concurrent findings of abnormal volitional cough and cough with swallow on clinical examination.

Acute Disease↗
PubMed1998

Age-related changes of the insular cortex and lateral ventricles: conventional MRI volumetric measures.

Preliminary data suggest that the insular region may be atrophied in patients with Alzheimer's disease when compared with healthy, age-matched control subjects. Therefore, normative data on age-related changes of the insular cortex were gathered and compared with age-related changes in the bodies of the lateral ventricles, which have been studied previously. Cerebrospinal fluid (CSF) volume of the lateral ventricles and insular cortical regions were measured on T1-weighted axial magnetic resonance images in 93 healthy subjects (age 21 to 84 years). Age-related changes were found in the lateral ventricles (r = 0.57, p < 0.0001) and in the CSF insular space (r = 0.42, p < 0.0001). Increasing age accounted for a significant amount of the variance for the lateral ventricle (pc = 0.45, p < 0.0001), but not for the insula (pc = 0.15, p = 0.14). Although there was a continuous linear increase in lateral ventricular volume with age, the CSF insular space increased linearly until the fourth decade, then plateaued until the seventh decade, with a linear increase thereafter. These data suggest that age-related changes occur in the region of the insular cortex, but differ from age-related changes of the lateral ventricles.

Adult↗
PubMed1998

Hand preference and magnetic resonance imaging asymmetries of the central sulcus.

Hand preference is perhaps the most evident behavioral asymmetry observed in humans. Anatomic brain asymmetries that may be associated with hand preference have not been extensively studied, and no clear relationship between asymmetries of the motor system and hand preference have been established. Therefore, using volumetric magnetic resonance imaging methodologies, the surface area of the hand representation was measured along the length of the central sulcus in 15 consistent right- and 15 left-handers matched for age and gender. There was a significant leftward asymmetry of the motor hand area of the precentral gyrus in the right-handers, but no directional asymmetry was found in the left-handers. When asymmetry quotients were computed to determine the distribution of interhemispheric asymmetries, the left motor bank was greater than the right motor bank in 9 of 15 right-handers, the right motor bank was greater than the left motor bank in 3 of 15 right-handers, and the motor banks were equal in 3 of 15 right-handers. In contrast, among left-handers, the left motor bank was greater than the right motor bank in 5 of 15, the right motor bank was greater than the left motor bank in 5 of 15, and the motor banks were equal in 5 of 15. Although no direct measure of motor dexterity and skill was performed, these data suggest that anatomic asymmetries of the motor hand area may be related to hand preference because of the differences in right-handers and left-handers. Furthermore, the predominant leftward asymmetry in right-handers and the random distribution of asymmetries in the left-handers support Annett's right-shift theory. It is unclear, however, whether these asymmetries are the result of preferential hand use or are a reflection of a biologic preference to use one limb over the other.

Adult↗
PubMed1997

Cognitive neuropsychological analysis and neuroanatomic correlates in a case of acute anomia.

We describe an analysis of lexical processing performed in a patient with the acute onset of an isolated anomia. Based on a model of lexical processing, we evaluated hypotheses as to the source of the naming deficit. We observed impairments in oral and written picture naming and oral naming to definition with relatively intact semantic processing across input modalities, suggesting that output from the semantic system was impaired. In contrast to previous reports, we propose that this pattern represents an impairment that arises late in semantic processing prior to accessing mode-specific verbal and graphemic output lexicons. These deficits were associated with a lesion in the posterior portion of the middle temporal gyrus or area 37, an area of supramodal association cortex that is uniquely suited as a substrate for the multimodal deficit in naming.

Aged↗
PubMed1997

The significance of body part as tool errors in limb apraxia.

When pantomiming to command, individuals with left hemisphere brain damage (LBD) often produce errors in which they use a body part as if it were the tool (BPT). Some clinicians question the significance of this type of error because subjects without brain damage at times also make BPT responses. We analyzed BPT errors in LBD and normal subjects who were reinstructed to modify the inappropriate BPT responses when they occurred. We also analyzed errors in normal subjects who were never reinstructed if a BPT occurred. Whereas LBD subjects who were reinstructed produced significantly more BPT errors than normals who were also reinstructed, LBD subjects were not different from normals who were not reinstructed. When reinstructed, normal control subjects correctly modified virtually all BPT errors, whereas LBD subjects did not modify BPT errors. These findings underscore the need for reinstruction when a BPT error occurs to determine whether it represents a true BPT error, a sign of limb apraxia.

Aged↗
PubMed1997

The role of the insular cortex in dysphagia.

Recent data indicate that dysphagia may occur following unilateral cortical stroke; however, the elucidation of specific cytoarchitectonic sites that produce deglutition disorders remains unclear. In a previous study of unilateral cortical stroke patients with dysphagia, Daniels et al. proposed that the insula may be important in swallowing as it was the most common lesion site in the patients studied. Therefore, 4 unilateral stroke patients with discrete lesions of the insular cortex were studied to further facilitate understanding of the role of the insula in swallowing. Dysphagia, as confirmed by videofluoroscopy, was evident in 3 of the 4 patients; all had lesions that involved the anterior insula, whereas the only patient without dysphagia had a lesion restricted to the posterior insula. These data suggest that the anterior insula may be an important cortical substrate in swallowing. The anterior insula has connections to the primary and supplementary motor cortices, the ventroposterior medial nucleus of the thalamus, and to the nucleus tractus solitarius, all of which are important regions in the mediation of oropharyngeal swallowing. Therefore, discrete lesions of the anterior insula may disrupt these connections and, thereby, produce dysphagia.

Cerebral Cortex↗
PubMed1997

Atrophy of the hippocampus, parietal cortex, and insula in Alzheimer's disease: a volumetric magnetic resonance imaging study.

The hippocampus, parietal cortex, and insula were measured on volumetric magnetic resonance imaging to determine whether patients with early Alzheimer's disease had significantly more atrophy than healthy controls. To determine whether the atrophy is limited to certain cortical regions, the striate cortex was measured because this area is not usually neuropathologically involved early in Alzheimer's disease. Eight mildly to moderately impaired patients who met National Institute of Neurological Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer's disease and eight controls who matched for age, gender, and educational level were studied. Atrophy was quantified in the following regions: hippocampus, parietal cortex, insular cortex, and striate cortex. The authors found significantly more atrophy of the hippocampus (p < 0.0001), parietal cortex (p < 0.025), and insula (p < 0.003) in the Alzheimer's patients. Measures of the striate cortex did not differ between the groups. There were no significant left-right differences in any of the regions measured. Their findings show that mildly to moderately impaired Alzheimer's patients have significantly more atrophy of the hippocampus, parietal cortex, and insula than healthy age-matched controls. Furthermore, this atrophy is probably discrete because the groups did not differ on measures of the striate cortex. Selective atrophy of the parietal and insular cortices has not previously been reported using the authors' methodology on volumetric magnetic resonance imaging. Their data suggest that the insula may be involved early in Alzheimer's disease and that atrophy of the insular cortex may contribute to the cognitive deficits typical of early Alzheimer's disease.

Aged↗
PubMed1996

Pars triangularis asymmetry and language dominance.

The pars triangular is a portion of Broca's area. The convolutions that form the inferior and caudal extent of the pars triangularis include the anterior horizontal and anterior ascending rami of the sylvian fissure, respectively. To learn if there are anatomic asymmetries of the pars triangularis, these convolutions were measured on volumetric magnetic resonance imaging scans of 11 patients who had undergone selective hemispheric anesthesia (Wada testing) to determine hemispheric speech and language lateralization. Of the 10 patients with language lateralized to the left hemisphere, 9 had a leftward asymmetry of the pars triangularis. The 1 patient with language lateralized to the right hemisphere had a significant rightward asymmetry of the pars triangularis. Our data suggest that asymmetries of the pars triangularis may be related to speech-language lateralization.

Adolescent↗
PubMed1996

Conventional MRI volumetric measures of parietal and insular cortex in Alzheimer's disease.

1. Although volumetric Magnetic Resonance Imaging (MRI) studies suggest regional cortical atrophy in Alzheimer's disease (AD), only one prior study documented atrophy of the parietal and insular cortex (Foundas et al, 1993). 2. To further investigate this potential early marker of AD, the authors computed volumetric measures of these regions on conventional axial MRI sections in 25 patients with mild to moderate "probable AD" and 25 age- and sex-matched controls. 3. Regions of interest (ROIs) from T1-axial images (5mm) were scanned into a PCX format (400 dots/inch) and volumes of CSF fluid were calculated using an Autocad program. 4. AD patients showed significant parietal (p < .01) and insular (p < .002) atrophy as compared to controls. 5. These findings suggest that atrophy of the parietal and insular cortex may occur early in AD patients, and that certain quantitative measures on conventional MRI accurately discriminate AD patients from controls.

Aged↗
PubMed1995

Morphologic cerebral asymmetries and handedness. The pars triangularis and planum temporale.

OBJECTIVE: To explore the relationship between morphologic cerebral asymmetries of the pars triangularis (PTr) and the planum temporale (PT) measured on three-dimensional, gradient-echo, magnetic resonance imaging scans of healthy right- and left-handed subjects. DESIGN: (Blinded) comparison of healthy right- and left-handed subjects who underwent magnetic resonance imaging. SETTING: The Seimens 1-T Magnetom (Seimens, Iselin, NH) at the University of Florida Health Science Center, Gainesville. SUBJECTS: Healthy right-handed (n = 8) and left-handed (n = 8) subjects matched for age, sex, and educational level. MAIN OUTCOME MEASURES: (1) Average length of the PTr (anterior ascending and anterior descending rami), (2) average length of the PT, (3) asymmetry quotients ([left-right]/[(left+right) (0.5)]) of the PTr and PT, and (4) combined asymmetry quotients of the PTr and PT. RESULTS: There was a significant leftward asymmetry of the PTr and PT in the right-handed subjects, but there was no significant asymmetry in the left-handed subjects. When the combined asymmetry quotient of the PTr and PT was calculated, the right-handed subjects had a leftward asymmetry (87.5% [n = 7]) or left was equal to right (12.5% [n = 1]), and the left-handed subjects had a leftward asymmetry (62.5% [n = 5]), left was equal to right (12.5% [n = 1]), or a rightward asymmetry (25% [n = 2]). In the left-handed subjects, writing posture seemed to predict these combined asymmetry quotients, ie, left-handed subjects using an inverted writing posture had a leftward asymmetry and left-handed subjects using a non-inverted writing posture had a rightward asymmetry of the perisylvian speech-language regions. CONCLUSIONS: On three-dimensional, gradient-echo, magnetic resonance imaging scans, we found a significant leftward asymmetry of the PTr and PT. When the groups were divided into right- and left-handed subjects, the former had a significant leftward asymmetry of the PTr and PT, while the latter did not. Measurements of the PTr and PT appear to be important indexes of the known functional asymmetries of the perisylvian speech-language regions.

Adult↗
PubMed1995

Gesture laterality in aphasic and apraxic stroke patients.

Limb preference during conversational gestures may be a reflection of functional hemispheric asymmetries. In right-handers, speech and praxis are usually mediated by the left hemisphere and in conversation, right-handers gesture more with their right than left hand. However, patients with left hemisphere brain damage, who are aphasic and apraxic but not hemiplegic, may use their right hemisphere to compensate for their left. Therefore, we investigated spontaneous lateralized gesture production during conversation in a group of left hemisphere-damaged stroke patients, who were aphasic and apraxic but not hemiparetic, and compared their performance to a group of matched controls. Whereas the control group had a strong right-hand preference, the nonparetic but apraxic and aphasic stroke patients were as likely to produce gestures with the right, left, or both hands.

Aged↗
PubMed1995

A preliminary study of the neuropsychological heterogeneity of familial schizophrenia.

This exploratory study describes the heterogeneity of the neuropsychological deficits that characterize familial schizophrenia. Forty-six familial schizophrenics showed significantly more variability in abstraction and problem-solving and motor control than 39 non-familial schizophrenics. Cluster analyses of these two neuropsychological parameters indicate that while the non-familial schizophrenics fall into one homogeneous cluster, the familial schizophrenics fall into three relatively distinct clusters which differ significantly in their morbid risk for schizophrenic-spectrum disorder. These preliminary data suggest that frontal lobe deficits are associated with an increased familial risk for schizophrenia.

Adolescent↗
PubMed1995

Ecological implications of limb apraxia: evidence from mealtime behavior.

Humans learn skilled acts in order to effectively interact with their environment. A loss of the ability to perform skilled acts is termed apraxia. Apraxia has been thought to be of theoretical interest, but the ecological implications of apraxia are controversial and have not been fully studied. We examined ten patients with unilateral left hemisphere cerebral infarctions (eight of whom were apraxic) and compared their mealtime eating behavior to a group of neurologically normal, age-matched controls. The stroke patients were less efficient in completing the meal. They made more action errors and were less organized in the sequencing of mealtime activities. Because the patients made more errors while using tools than when performing nontool actions, their deficit could not be accounted for by an elemental motor deficit. A positive relationship was found between mealtime action errors and the severity of apraxia. These findings suggest that limb apraxia may adversely influence activities of daily living.

Activities of Daily Living↗
PubMed1995

Apraxia during Wada testing.

Apraxia is the loss of the ability to perform learned skilled movements correctly. In right-handers, apraxia and aphasia are most frequently associated with left-hemisphere lesions. When they are dissociated, however, aphasia is more common in the absence of apraxia than vice versa. There are two hypotheses that can account for this discrepancy: (1) in right-handers, praxis is more likely than language to be mediated by the right hemisphere, or (2) the left-hemisphere network that mediates language is either more widely distributed than the network that mediates praxis or is more likely to be in the middle cerebral artery distribution. We studied apraxia in a group of right-handers undergoing selective hemispheric anesthesia, or Wada testing. All nine subjects had language lateralized to the left hemisphere, and seven of the nine had praxis lateralized to the left hemisphere. Two of the subjects had praxis bilaterally represented. Although our data suggest that speech and praxis functions tend to be lateralized to the left hemisphere in most right-handers, praxis appears to be more distributed between the hemispheres than speech-language functions. Furthermore, an analysis of the types of errors made during praxis testing suggests differential roles of the hemispheres in praxis functions.

Adolescent↗
PubMed1994

Planum temporale asymmetry and language dominance.

Language is lateralized to the left hemisphere in most individuals, and leftward asymmetry of the planum temporale has been reported in postmortem and imaging studies. In this study we measured the planum temporale on magnetic resonance imaging (MR) scans of patients (11 right-handers, 1 non-right-hander) who had selective hemispheric anesthesia or Wada testing performed for language lateralization. All subjects who had language lateralized to the left hemisphere (11 right-handers) had a leftward asymmetry of the planum temporale. One subject who had language lateralized to the right hemisphere (non-right-hander) had a strong rightward asymmetry of the planum temporale. These data suggest that planum temporale asymmetries determined by MR are associated with language dominance and may predict language laterality.

Adolescent↗