Left-handed Patients Research Articles

Superior temporal gyrus volume abnormalities and thought disorder in left-handed schizophrenic men.

Studies of schizophrenia have not clearly defined handedness as a differentiating variable. Moreover, the relationship between thought disorder and anatomical anomalies has not been studied extensively in left-handed schizophrenic men. The twofold purpose of this study was to investigate gray matter volumes in the superior temporal gyrus of the temporal lobe (left and right hemispheres) in left-handed schizophrenic men and left-handed comparison men, in order to determine whether thought disorder in the left-handed schizophrenic men correlated with tissue volume abnormalities. Left-handed male patients (N = 8) with DSM-III-R diagnoses of schizophrenia were compared with left-handed comparison men (N = 10) matched for age, socioeconomic status, and IQ. Magnetic resonance imaging (MRI) with a 1.5-T magnet was used to obtain scans, which consisted of contiguous 1.5-mm slices of the whole brain. MRI analyses (as previously defined by the authors) included the anterior, posterior, and total superior temporal gyrus in both the left and right hemispheres. There were three significant findings regarding the left-handed schizophrenic men: 1) bilaterally smaller gray matter volumes in the posterior superior temporal gyrus (16% smaller on the right, 15% smaller on the left); 2) a smaller volume on the right side of the total superior temporal gyrus; and 3) a positive correlation between thought disorder and tissue volume in the right anterior superior temporal gyrus. These results suggest that expression of brain pathology differs between left-handed and right-handed schizophrenic men and that the pathology is related to cognitive disturbance.

The influence of handedness on the clinical presentation and neuropsychology of Alzheimer disease.

Research on the influence of handedness on the clinical presentation and neuropsychology of Alzheimer disease (AD) is scarce. To compare clinical presentation and neuropsychological test performance of right- and left-handed patients with AD. We hypothesized that left-handedness would be associated with younger onset, more rapid progression, and possibly cognitive hemispheric asymmetry. After determining handedness with the Edinburgh Inventory for Handedness for 922 patients with AD, 18 left-handed patients were compared with 18 right-handed patients matched individually on Mini-Mental State Examination scores, education, and age. We compared clinical characteristics (eg, age of onset), estimated rate of initial cognitive decline, language and visuospatial test performances, and patterns of cognitive and motor asymmetries for the 2 groups. Alzheimer's Disease Research Center at Baylor College of Medicine, Houston, Tex. Results of the Wechsler Adult Intelligence Scale-Revised verbal and performance IQ tests, the Western Aphasia Battery sequential commands subtest, the Boston Naming Test, the Halstead-Reitan Finger-Tapping Test, and the calculated Rate of Initial Progression. We found that left-handed patients had younger ages of onset but unexpectedly lower estimated rates of initial cognitive decline, and their results on language tests did not differ from those of right-handed patients. Regarding asymmetry, left-handed patients were more likely than right-handers to obtain lower verbal IQ than performance IQ scores and to exhibit faster finger-tapping speeds with their nondominant hand, but group differences did not attain statistical significance. There were disproportionately few left-handed patients with AD compared with population norms. Left-handed patients with AD do not differ from right-handed patients in the severity or pattern of neuropsychological deficits. Left-handedness or some factor associated with it may contribute to the early appearance of cognitive deficits during the development of Alzheimer disease, but may temper the subsequent rate of progression of deficits.

Callosal disconnection syndrome in a left-handed patient due to infarction of the total length of the corpus callosum

We report on a left-handed patient with an ischemic infarction affecting exclusively the total length of the corpus callosum. This lesion clinically correlated with an almost complete callosal disconnection syndrome as described in callosotomy subjects, including unilateral verbal anosmia, hemialexia, unilateral ideomotor apraxia, unilateral agraphia, unilateral tactile anomia, unilateral constructional apraxia, lack of somesthetic transfer and dissociative phenomena. Despite the patients left-handedness, his pattern of deficits was similar to the disconnection syndrome found in right-handers. Our report focusses on motor dominance and praxis. We followed-up the improvement in left apraxia and investigated the ability to initiate and learn a new visuo-motor skill. The results permit two tentative assumptions: (1) that the improvement in left apraxia was due to a compensatory increase in ipsilateral proximal muscle control, and (2) that motor dominance, i.e. the competence to initiate and learn a new movement pattern, was hemispherically dissociable from manual dominance in the sense of praxis control.

Alexia sin agrafia por lesión cerebral en varón diestro

A 65 year-old man, right-handed, without any family history of left handiness, suddenly developed a left homonymous hemianopia and incapacity for reading. Neurological and neuropsychological examinations showed the presence of a profound alexia with preservation of writing to dictation and spontaneously. He was unable to read what he had written. He could spell the words letter by letter but he was unable to read the complete word. MRI showed an extensive infarct in the territory of the right posterior cerebral artery. The infarct extended anteriously to the right thalamus and to the medial temporal fifth or fusiform gyrus. The splenius was spared. Brain SPECT disclosed the area of the infarct and an extensive area of decreased cerebral perfusion over the right parietal and temporal areas. Alexia without agraphia has been reported in right-handed patients with left occipital lesions and in right occipital regions in left-handed patients but rarely if ever in right occipital lesions in right-handed patients.

Localization of Language-Related Cortex with15O-Labeled Water PET in Patients with Gliomas

Measurement of relative cerebral blood flow (CBF) with15O-labeled water PET has been widely used for brain mapping experiments on language functions in normal volunteers and patients with epilepsy. We focused on the question of whether PET during speech activation is an appropriate method for noninvasive determination of language-related cortex in patients with brain tumors. Furthermore, the suitability of the method for determination of hemispheric language dominance was examined and compared to the results of the Edinburgh Handedness Inventory. Ten right-handed and six left-handed patients with gliomas were examined prior to surgery while repeatedly performing word repetition and verb generation tasks. A set of volumes of interest (VOIs) was drawn on coregistered MRI in order to account for anatomic variability as well as anatomical alterations due to tumor mass effect. Repetition of nouns did not produce significant hemispheric differences. During stimulation by verb generation, reliable lateralized activations of Broca's area and supplementary motor area were detected in all right-handed patients. Of the left-handed patients, two showed clear right lateralization, two activated Broca's area bilaterally, and two had a pattern similar to that of right-handers. Patients with bilateral activations showed the strongest tendency toward bihandedness according to the handedness inventory. Lateralization of supplementary motor area in left-handers corresponded to lateralized activity in Broca's area. Tumors in the vicinity of language-related regions did not alter activation responses. In conclusion, measurement of CBF changes during verb generation permits identification of language-related areas in patients with gliomas with strong lateralization related to hemispheric dominance. These findings may be of particular clinical interest for left-handed patients.

Lateralization of cerebellar activation in word retrieval is ruled by the location of Broca's area. PET evidence in normal controls and in a left-handed epileptic patient.

Lateralization of cerebellar activation in word retrieval is ruled by the location of Broca's area. PET evidence in normal controls and in a left-handed epileptic patient.

Left-right differences in motor thresholds after stimulation of the globus pallidus before pallidotomy

Left-right upper limb motor threshold differences were found after electrical stimulation of the globus pallidus administered as a neuroprotective measure to avoid lesioning of the internal capsule during stereotactic pallidotomy...

CT assessment of jugular foramen dominance and its association with hand preference.

Three hundred and seven normal CT scans of the head were prospectively analysed to assess jugular foramen dominance. After assessment, hand preference was elicited. Of these, 276 were right-handed and 31 were left-handed. Of the right-handed patients: 180 had a larger jugular foramen on the right; 63 had a larger jugular foramen on the left; and in 33 no difference could be discerned. Of the left-handed patients: 11 had a larger jugular foramen on the right; 16 had a larger jugular foramen on the left; and in four no difference could be discerned. The results suggested a significant association between jugular foramen dominance and hand preference.

Preserved Semantic Priming Effect in Alexia

BH, a left-handed patient with alexia and nonfluent aphasia, was presented with a lexical-decision task in which words and pronounceable pseudowords were preceded by semantically related or unrelated picture primes (Experiment 1). In Experiment 2, BH was given an explicit reading task using the word lists from Experiment 1. Performance on Experiment 2 disclosed severe reading deficits in both oral reading and semantic matching of the words to pictures. However, in Experiment 1, BH demonstrated a significant semantic priming effect, responding more accurately and more quickly to words preceded by related primes than by unrelated primes. The present results suggest that even in a patient with severe alexia, implicit access to semantic information can be preserved in the absence of explicit identification. The possibility of categorical gradient in implicit activation (living vs. nonliving) in BH was also discussed, which, however, needs to be clarified in the further investigation.

Correlates of left-handedness in a large sample of schizophrenic patients

Questionnaire data concerning hand preference from the parents of 686 schizophrenic patients were used to test predictions relevant to neurodevelopmental models of schizophrenia. In line with predictions, left-handed patients (n = 94) had a more frequent history of difficult birth, more childhood cognitive and behavioural abnormalities and more persistent auditory hallucinations than did right-handed patients.

Retained Language in Dysgenic Cortex

SINCE THE ADVENT of magnetic resonance imaging, there has been renewed interest in disorders of cortical migration in the cause of focal epilepsy. The function of dysplastic cortex is poorly understood. We report a 46-year-old woman in whom this was assessed by intraoperative stimulation. This left-handed patient had a 30-year history of complex partial seizures with secondary generalization. Prolonged electroencephalographic recordings documented an epileptic focus in the right lateral and inferomesiotemporal lobe. Computed tomographic scanning and angiography suggested a right posterotemporal hamartoma. Amytal testing showed major speech representation in the right hemisphere. At craniotomy, an ivory-colored, posterotemporal lesion originating 5 cm from the temporal tip and 4 cm in diameter occupied the posterotemporal region. Electrical stimulation of this lesion produced speech interference. A histological examination of the resected anterotemporal lobe, amygdala, and hippocampus and biopsy specimens of the lesion showed extensive multifocal cortical microdysgenesis and gliovascular and cortical hamartoma. This case shows that grossly dysplastic cortex can remain functional. Cortical mapping under local anesthesia should be performed before resection of dysplastic lesions in putatively functional areas in patients with intractable epilepsy.

Impaired phonological reading in primary degenerative dementia

SUMMARY This case study reports the profile of preserved and impaired capacities in a left-handed patient suffering from primary degenerative dementia of unknown aetiology. She was remarkable because her relatively preserved object naming and semantic categorization abilities contrasted with severe deficits in speech fluency, oral reading, inability to execute spoken and written commands, and severely impaired auditory-verbal short-term memory. Her reading disorder could be characterized as a disturbance of assembled phonology. She had great difficulty reading pronounceable nonwords, but she could correctly read irregular words. She showed effects of word imageability or concreteness (more than word frequency). She also showed effects of part-of-speech, where nouns and adjectives were read more easily than inflected verbs. She had difficulty reading function words. The syntactic category effects could be proven (by hierarchical log-linear analysis) not to be an artefact of imageability differences between verbs, adjectives and nouns. In reading aloud she made visual and morphological errors, but no semantic errors. This interesting pattern of preserved semantic information and disrupted phonological processing is unusual in dementia and contrasts with the severe dysnomia of patients with surface dyslexia who are able to read by the indirect, assembly-of-phonology route and show better reading of nonwords than irregular words. Her reading by a direct visual-semantic route appeared to be associated with relatively intact object naming, concrete word reading, and irregular word reading, This selective impairment of phonological reading in the context of partly preserved semantic abilities was interpreted as confirmation of the dissociability of language functions in primary degenerative dementia.

Ideatory apraxia in a left-handed patient with right-sided brain lesion

Ideatory apraxia in a left-handed patient with right-sided brain lesion

Unilateral Dysgraphia of the Dominant Hand in a Left-Hander: A Disruption of Graphic Motor Pattern Selection

This paper reports the case of an English speaking, fully left-handed patient (DS) with a left unilateral writing deficit occurring after a subarachnoid hemorrhage due to the rupture of an anterior communicating aneurysm. DS's performance, in spelling and in right-handed writing was entirely preserved while his left handed writing was characterized by the production of errors which could generally be spontaneously self-corrected. Errors produced with lower-case letters differed from the ones produced with upper case letters: The former usually, corresponded to letter substitutions which were characterized by a high degree of physical similarity between the target letter and the one produced. The latter tended to result in the production of aborted letters. This impairment is discussed in the context of cognitive models of writing. It is suggested that graphic motor patterns for lower-case letters and for upper-case letters are different in nature and consequently that production processes may also differ.

Dichotic words listening test. Technical aspects and results in normal right-handed individuals.

Dichotic listening tests have been being used in an increasing frequency to determine in a non-invasive way the cerebral dominance in right- and left-handed patients. This is especially relevant when surgery in eloquent brain areas is being contemplated. A Portuguese version of the dichotic words listening test was developed based mainly on Wexler's protocol. It consisted of 15 pairs of words with a stimulus dominance lower than 50%. They were recorded using natural voice and time and intensity synchronization by means of a specialized software. Each pair of words was presented twice in different channels within each block. The items were randomized and presented with a 300 msec interval between each trial. Four blocks of 30 pairs of words each were created, totalizing 120 trials. In the scoring process, the words heard over the right and left ears were wrote down. The number of times each word was heard over each ear was computed and their values subtracted yielding a partial score for each specific word pair. This process was repeated for all stimuli pair and a final score for right and left predominance was then reached. Thirty-two right handed normal individuals underwent the test. 93.8% showed a right ear advantage. These results are very similar to the actual left hemisphere dominance rate in a right-handed population.

The prevalence of autoantibodies among right and left handed schizophrenic patients and control subjects

Sera from schizophrenic patients (n = 186) and healthy control subjects (n = 346) were tested for the presence of seven common autoantibodies by standard immunological methods. The association between handedness and autoantibodies was tested in a multiway contingency table using a log-linear model. For men, but not women, nondextrals (patients and controls) were twice as likely to test positive for autoantibodies than dextrals (p = 0.0002). Although more women (33%) than men (24%) tested positive for autoantibodies, handedness was not a distinguishing factor among women. These data suggest that sinistrality and gender are associated with autoantibodies in a subgroup of schizophrenic patients and healthy control subjects.

Left-handed first-episode, neuroleptic-naive schizophrenic patients have a higher prevalence of autoantibodies

Using standard immunological techniques, sera from first-episode, neuroleptic-naive schizophrenic patients ( n = 51) and age, race and sex matched healthy controls ( n = 51) were screened for seven common autoantibodies. Significantly more left-handed (67%) than right-handed (23%) schizophrenic patients had autoantibodies ( p = 0.011). Left-handed schizophrenic patients were six times more likely than right-handed patients or controls and four times more likely than left-handed controls to test positive for autoantibodies ( p = 0.012). These data suggest that disease and sinistrality contribute to the excess of autoantibodies in schizophrenia.

Impairment of Action to Visual Objects in a Case of Ideomotor Apraxia

Abstract A single-case study is reported of a left-handed patient (GF) who presented with a unimanual left-handed apraxia following lesions of the right temporal and frontal lobes. GF was particularly impaired at making learned left-handed gestures to visual stimuli, and he was rather better at left-hand gestures when given visual and tactile input and when asked to gesture to the name of the object. GF was relatively good at making right-hand gestures to objects irrespective of the modality of presentation. He also had intact proprioceptive and/or kinesthetic knowledge of the correct left arm and hand movements to make. GFs performance improved when he was asked to make an appropriate intervening action with his right hand, or when he had to perform simple repetitive actions with his left hand in between making gestures to a series of objects. GFs case supports the argument for a direct route mapping visual input to action. His impairment is attributed to a problem in inhibiting inappropriate actions wit...

Neuropsychological Sequelae of Stroke as a Function of Handedness

The preservation of visuospatial ability relative to verbal ability following right middle cerebral artery stroke was assessed in 19 left- and 19 right-handed male patients who were group-matched on the basis of age, education, and time elapsed since stroke. Analysis of covariance (covarying education) indicated that the left- and right-handed groups were significantly different with regard to the discrepancy between Verbal IQ and Performance IQ, with the left-handed patients showing a smaller difference than the right-handers. These results provide further evidence that sinistrality may be associated with less hemispheric specialization.

Left-handedness in male schizophrenic patients is associated with increased impairment on the Luria-Nebraska neuropsychological battery

Several studies suggest increased mixed and left-handedness in schizophrenia. This is of interest as early cerebral injury can result in increased left-handedness and some investigations have suggested a role for early developmental insult (e.g., birth complications) in schizophrenia. We administered the Luria-Nebraska Neuropsychological Battery (LNNB) to 24 left-handed male schizophrenic patients and a separate group of 24 right-handed schizophrenic patients who were age and education matched to the left-handed patients. The test protocol also was administered to 15 left-handed non-psychiatric control subjects and 15 right-handed controls. Direct comparisons ( t-test) of the left- to right-handed schizophrenics revealed that the left-handed patients showed significantly greater impairment on several LNNB measures sensitive to cognitive deficits in schizophrenia. There were no differences between left- and right-handed control subjects. A further 2 × 2 ANOVA pooling all subjects noted several significant interactions between handedness and diagnostic group. The findings suggest a unique interaction between left-handedness and neuropsychological impairment in schizophrenia and could support a relationship between left-handedness, early cerebral insult, and cognitive deficits.