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M P Alexander

Publications and source records attributed to M P Alexander.

At least 19 recordsLinked to original sources
PubMed1995

Neuropsychological and neuroanatomical correlates of confabulation.

In the present exploratory investigation we report nine confabulatory patients of comparable age, education, and general level of intelligence in the acute epoch of recovery after rupture and clipping of ACoA aneurysms. Five of the nine cases had "spontaneous" confabulation, severe anterograde amnesia, markedly poor attentional and executive functions, and denial of illness. These patients all had multiple lesions that involved basal forebrain, ventral frontal lobe, and striatum. The other four patients manifested only "momentary" or "provoked" confabulations. These patients also had severe anterograde amnesia but showed relatively mild deficits in executive functions. These patients had lesions restricted to the basal forebrain except for one who had additional orbital frontal damage. Analysis of these two groups of confabulatory patients suggests that there is a common profile of deficits and anatomic foundation associated with confabulation; "spontaneous" confabulation appears to require extensive, simultaneous disruption of medial basal forebrain and frontal cognitive systems resulting in profound executive and memory deficits, whereas more limited lesions to the basal forebrain or orbital frontal cortex will result in "transient" or "provoked" confabulatory responses and a more restricted profile of cognitive deficits.

Adult↗
PubMed1995

Subcortical aphasia: distinct profiles following left putaminal hemorrhage.

Numerous reports of aphasia after subcortical lesions have produced incomplete agreement about basic clinico-anatomic correlations. Some disagreement has arisen from methodologic differences. To control for some of the common differences, we analyzed 13 patients with left putaminal hemorrhage controlled for location--subcortical but not thalamic, and for time postonset--studied in both acute and postacute epochs. There was no apparent correlation between lesion site and acute language profiles. During the postacute epoch, there were several distinct correlations between lesion site (postacute decreased CT density) and specific aphasia dimensions--nonfluency, impaired comprehension, and perhaps impaired repetition. Our correlations were compatible with comparably controlled cases in the literature. A corollary result of this study is that patients fluent during the early epoch are likely to have a better outcome, and those initially nonfluent have a poor prognosis for language recovery.

Aged↗
PubMed1995

Amnesia following traumatic bilateral fornix transection.

There is controversy regarding the effect of isolated fornix damage on human memory. We report a patient who suffered a traumatic penetrating head injury that resulted in a significant and persistent anterograde amnesia. CT revealed a lesion that involved the region of the proximal, posterior portion of both fornices without evidence of damage to other hippocampal pathways or to other structures known to be critical for memory, such as the hippocampus, thalamus, or basal forebrain. The unique location of the lesion in this patient provides evidence supporting the role of isolated fornix lesions in amnesia.

Adult↗
PubMed1994

Traumatic brain injury. Predicting course of recovery and outcome for patients admitted to rehabilitation.

OBJECTIVE: To demonstrate that the prognosis for patients with traumatic brain injury (TBI) admitted to rehabilitation can be established with use of principled neurologic diagnosis and predictor variables of established value in neurosurgical populations. DESIGN: A cohort of patients with TBI accumulated at rehabilitation admission were followed up for 1 year. Severity measures (Glasgow Coma Scale score, length of coma, and duration of posttraumatic amnesia) and information to generate neuropathologic profiles were gathered retrospectively and prospectively; outcome measures were obtained prospectively. SETTING: The TBI rehabilitation unit in a freestanding rehabilitation hospital. PATIENTS: A consecutive sample of 243 patients with TBI admitted to a rehabilitation unit (age range, 8 through 89 years). MAIN OUTCOME MEASURES: Functional outcome measured by the Glasgow Outcome Scale at 6 and 12 months after injury. RESULTS: Posttraumatic amnesia had a clear, predictable relationship to length of coma in patients with diffuse axonal injury (R2 = .58, P < .0001). Severity measures, particularly duration of posttraumatic amnesia, correlated with the Glasgow Outcome Scale score at 6 and 12 months after injury (R2 = .45, P < .0001, R2 = .48, P < .0001), strongly in patients with diffuse axonal injury but poorly in patients with primarily focal brain injury. Age was an important factor in recovery, beginning at age 40 years; older patients had significantly longer posttraumatic amnesia and worse functional outcome at any severity. CONCLUSIONS: The early course of recovery and functional outcome in TBI can be characterized in neurorehabilitation populations and is highly dependent on specific neuropathologic diagnosis, severity, and age. Predictions that employ traditional measures of severity are most relevant in patients with diffuse axonal injury. Age has a potent, complex effect on recovery, particularly beyond age 40 years.

Adolescent↗
PubMed1994

Subcortical aphasia: the core profile of capsulostriatal infarction.

There has been disagreement about the precise characteristics of "subcortical aphasia." We evaluated 14 patients with aphasia after subcortical lesions and controlled for duration, general anatomic site of lesions (capsulostriatal only), and etiology. The clinical profiles of the patients were quite similar, varying in severity in rough proportion to lesion size and varying in quality in proportion to anterior paraventricular extent. Large lesions were associated with impaired "executive" and "generative" language functions. Similar aphasia profiles in patients with deep frontal and paraventricular white matter lesions suggest that damage to a frontal-caudate functional system underlies a "core" aphasia profile in these patients.

Aged↗
PubMed1992

Lesion localization in apractic agraphia.

Apractic agraphia is an impairment in writing in which the actual orthographic production of letters and words is abnormal despite normal sensorimotor function, visual feedback, and word and letter knowledge. We report one case and review the limited clinicoanatomical literature. Analysis of available cases supports the hypothesis that apractic agraphia is one of several related clinical disorders that are due to the loss of spatially and kinesthetically modulated movements. It is produced by lesions in the superior parietal lobule, usually in the hemisphere dominant for language.

Aged↗
PubMed1992

Lesion localization of phonological agraphia.

Phonological agraphia is a neurolinguistically specific profile of spelling impairment. It is characterized by an impairment in spelling pronounceable pseudowords ('sild') and by an impairment in spelling real words related to their familiarity, length, and often, part of speech (Shallice, 1981; Roeltgen, 1985; Bub & Chertkow, 1988). We report two cases of phonological agraphia, each with a different lesion profile. Analysis of the small number of published cases that include lesion data, plus our own cases, suggests that phonological agraphia can be produced by lesions in a wide range of perisylvian cortical regions that have in common some role in central phonological processes.

Agraphia↗
PubMed1992

Neuropsychological and neuroanatomical dimensions of ideomotor apraxia.

Fifty-five right-handed men with left hemisphere stroke were systematically investigated for ideomotor apraxia of various body parts. Standardized aphasia and apraxia examinations in all cases, and appropriately timed CT in 28 cases, were used for analysis of psychological and anatomical properties of ideomotor apraxia. It is not possible to ignore the modality of eliciting the movement (command or imitation) and the body part being moved (buccofacial, limb or whole body) from any comprehensive theory about ideomotor apraxia. Different levels of performance are seen with different body parts to different modalities in different aphasic groups. Some subtypes of ideomotor apraxia (buccofacial) have highly specified anatomical basis. Some (limb) have apparently distributed anatomies, and others (whole body) have as yet unknown bases.

Adult↗
PubMed1991

Reversed lateralization of cognitive functions in right handers. Exceptions to classical aphasiology.

Most current and past research on the cerebral organization of cognitive functions has presupposed certain specialized hemisphere operations. At least for right handers, language and praxis are to be organized in the left hemisphere, while affective prosody, configurational spatial capacity, and global attention are lateralized in the right hemisphere. Deviations from these presuppositions, as in crossed aphasics and perhaps left handers, are generally considered to be 'exceptions' and either to disprove the rules or to be irrelevant to the rule. We report 4 very 'exceptional' cases, right handers with almost entirely reversed lateralization of functions. Analysis of the intrahemispheric relationships between functions suggests that there may be a specific neurobiology to the interrelationships between and among cognitive functions, handedness, and the intrahemisphere localization of the function.

Adult↗
PubMed1990

Broca's area aphasias: aphasia after lesions including the frontal operculum.

We report 9 cases of aphasia following lesions in the region of the left frontal operculum. It is not possible to capture their variety of clinical manifestations with the simple labels of "Broca's area aphasia." or "Broca's area aphasia." Analysis of the breakdown of various components of speech and language in these cases suggests that the operculum, lower motor cortex, and subjacent subcortical and periventricular white matter contain critical parts of different language systems. These systems can be independently impaired. There are several common language syndromes that follow damage that includes the left frontal operculum. These syndromes reflect the effects of the direction and extent of the lesion in the various language systems.

Adult↗
PubMed1989

Distributed anatomy of transcortical sensory aphasia.

We examined four patients with transcortical sensory aphasia and eight with milder language disturbances but with similar thalamic and/or temporo-occipital lesions. Specific attention was paid to differentiation of the computed tomographic lesion site of the milder cases from the transcortical sensory aphasia cases. The critical lesion for transcortical sensory aphasia in these patients involved pathways in the posterior periventricular white matter adjacent to the posterior temporal isthmus, pathways that are probably converging on the inferolateral temporo-occipital cortex. Analysis of the language function of these patients, of the influence of sensory modalities on language function, and of the interaction between semantic memory and semantic lexical functions suggests the existence of a specific brain system for semantic functions. This semantic system has a particular distributed anatomy. We propose that damage to this system may have a variety of clinical manifestations in language and in memory, depending on the exact lesion configuration.

Aged↗
PubMed1989

Written spelling agraphia.

When a disorder of single word writing is seen in conjunction with preserved oral spelling and intact written grapheme formation ("written spelling agraphia"), the deficit may be presumed to lie somewhere between letter choice and written motor output. Two potential deficits are considered: (1) visual letter codes are not activated properly and (2) the information contained within properly activated visual letter codes fails to reach intact graphic motor patterns. Two patients with written spelling agraphia were each given a series of tests aimed at distinguishing between the two possibilities. Results suggest that the written spelling agraphia seen in these two patients arises from different underlying deficits. The results are discussed in terms of the patients' CT scan lesion sites, which were markedly different.

Agraphia↗
PubMed1989

Frontal lobes and language.

Numerous theories discuss the neuropsychological functions of the frontal lobes, most based on some concept of supramodality, and an extensive literature presents the phenomenology and semiology of language and communication deficits after focal brain lesions involving the frontal lobes. Despite this, few attempts have been made to link the clinical phenomenology to a theory. This paper presents (1) a general theory of frontal functions; (2) a brief summary of experimental and anatomical literatures in support of defined frontal functional systems; (3) clinical observations that delineate these functional systems for the specific modalities of language and communication; (4) a review of the available literature supporting the idea of specific modal and supramodal language and communication capacities; (5) hypotheses about the distributed anatomy of these functional systems; and (6) implications for traditional clinical notions of aphasia, particularly in relation to a general theory of frontal lobe functions.

Aphasia↗
PubMed1989

Crossed aphasias can be mirror image or anomalous. Case reports, review and hypothesis.

Individual cases of crossed aphasia (aphasia after a right hemisphere lesion in a right-hander) have often been reported. A number of theories have been proposed as to the neuropsychological and/or nerobiological mechanisms that might underlie this phenomenon, but there is still disagreement about its language phenomenology and possible significance. We report 2 cases of crossed aphasia after stroke and review 34 cases from the literature with anatomical documentation of lesion site. Analysis of this material suggests that they represent at least two populations. There may be general conclusions concerning mechanisms of cerebral lateralization to be learned from the investigation of anomalous groups such as crossed aphasics.

Aged↗
PubMed1989

Creutzfeldt-Jakob disease presenting as isolated aphasia.

Progressive aphasia without dementia (primary progressive aphasia) is increasingly recognized as an important neurobehavioral syndrome. Clinical diagnosis of progressive aphasia is difficult early in its course, and the differential diagnosis is usually said to include Alzheimer's and Pick's diseases. We report a 61-year-old man with autopsy-proven Creutzfeldt-Jakob disease (CJD) whose major initial manifestation was a progressive, fluent aphasia. Myoclonus was absent, and characteristic EEG abnormalities appeared relatively late. We believe that this case of CJD is unique in its presentation of profound and isolated aphasia. CJD should be considered in the differential diagnosis of the progressive aphasia syndrome.

Aphasia↗
PubMed1989

Traumatic basal ganglia hemorrhage: clinicopathologic features and outcome.

Traumatic basal ganglia hemorrhage (TBGH) is probably secondary to rupture of lenticulostriate or anterior choroidal arteries. We evaluated 6 consecutive cases of this entity to define its clinical and pathologic dimensions. Relative frequency of TBGH was 3% (3 left, 3 right) in this acute rehabilitation population. Lesion size and associated pathology varied. Contralateral hemiparesis, present in all, recovered to varying extents, apparently related to lesion location (posterior limb, internal capsule, or midperiventricular white matter), not size. Prolonged muteness occurred in 4 of 6; these 4 patients also had severe diffuse axonal injury. Clinical findings corresponded with previously recognized subcortical hemisphere profiles. All achieved a moderate disability or good recovery rating on the Glasgow Outcome Scale. Rather than any features of the TBGH itself, duration of coma and/or associated temporal herniation predicted slower recovery and worse outcome. In conclusion, TBGH is a rare entity compatible with a favorable recovery, especially when occurring in isolation. The hemorrhage itself determines clinical signs related to particular subcortical structures involved and the side of the lesion. Overall cognitive impairment and speed and quality of recovery are more related to associated cerebral damage.

Adolescent↗
PubMed1989

An improved cellophane method for in vitro germination of recalcitrant pollen.

The cellophane technique of La Cour and Faberge has been improved by the use of a booklet of filter paper. The booklet consists of seven squares of filter paper stapled together; the cellophane on which the pollen is germinated is placed between the two top leaves of the booklet and the whole soaked in a sucrose-based nutrient medium for 15 min. This arrangement keeps the cellophane flat as it absorbs medium. The top leaf of the booklet is then removed, the pollen dusted on it and the completed preparation closed in a plastic-wrapped Petri dish. The lower leaves of the booklet keep the cellophane moist for up to 24 hr. Proportions of pollen grains germinating are at least as high as in the hanging drop method; pollen of species that germinate poorly or not all in hanging drops do well in this technique. Because the pollen tubes adhere tightly to the cellophane, staining, observation, and studies of various sorts are facilitated.

Agriculture↗