Positron emission computed tomography in the diagnosis of dementia.
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Biomedical subjects
Publications and source records attributed to D F Benson.
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Deficits in attention have been strongly linked with both schizophrenia and pathology in the prefrontal cortex. This observation was tested by administering a battery of commonly used tests of attention, sustained mental activity, and tracking to 16 patients who had undergone prefrontal leucotomy approximately 25 years earlier. Presurgical diagnosis in each patient was schizophrenia. The 16 were divided into three groups based on their recovery after surgery. A control group of nonleucotomized schizophrenics was established to control for psychiatric symptomatology. A second control group consisted of subjects without history of psychiatric or CNS disorder. In general, there was no statistically significant impairment of performance in attention tests between the patients with prefrontal psychosurgery and the normal control subjects. The nonoperated schizophrenic control group performed most poorly. Lesion chronicity, interaction of leucotomy and presurgical psychiatric state, and conditions of test administration are suggested as possible explanations for the unexpected results.
The pitfalls of overlooking correctable causes of progressive intellectual deterioration are illustrated by live patients whose conditions were originally diagnosed as primary dementia. In each case careful evaluation disclosed a reversible process. Treatable intracranial conditions, systemic illnesses, endocrinopathies, deficiency states, collagen-vascular disorders, heavy-metal intoxications, exposure to industrial agents, infections, and the effects of drugs must all be considered in the evaluation of the patient with dementia. Such conditions are less likely to go undiagnosed when dementia is regarded as a nonspecific syndrome of progressive intellectual compromise rather than a specific diagnosis.
Memory and language were evaluated in patients with temporal lobe epilepsy and generalized epilepsy. Subjects were matched for age, duration of illness, and seizure frequency, and grouped according to the electroencephalographic results and seizure type into right temporal, left temporal, and generalized. In formal tests of intelligence, auditory and visual memory, and language, a significant difference was noted only on a confrontation naming test. The mean score on this test was considerably lower in the left temporal group; right temporal and generalized groups scored in the normal range. This correlated with impairment on many verbal subtests of intelligence and memory. These results suggest that the interictal memory impairment of temporal lobe epilepsy may be an anomia and that the anomia may contribute to impairment of verbal learning and memory; both circumlocution and circumstantiality may compensate for anomia.
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Partial recovery from aphasia was documented in an individual rendered hemiplegic and globally aphasic by embolic infarction in the distribution of the left middle cerebral artery. Computed tomography showed total destruction of the classical left hemisphere language areas, indicating that the right hemisphere was responsible for the improved linguistic function. This observation is consistent with right hemisphere language capacity demonstrated after left hemispherectomy or commissurotomy. Right hemisphere language function may underlie much of the recovery from aphasia after injury of the left hemisphere.
Three patients with complex partial seizures experienced prolonged episodes of aimless wandering followed by retrograde amnesia for the experience, a phenomenon called poriomania. Our experience and the literature suggest that this behavior is a prolonged postictal automatism and is not psychogenic. Adjustments of anticonvulsant therapy eliminated this behavior in all three of our patients.
A patient recovering from a severe head injury developed a prolonged Capgras syndrome in which he believed his wife and five children had been replaced by nearly identical substitutes. Although this phenomenon is considered a functional disorder in the psychiatric literature, recent reports postulate an organic basis. Recent studies of the comparable neurologic disorder, reduplicative paramnesia, have stressed the importance of bilateral frontal and right hemisphere pathology. Neuropsychologic and neuroradiologic data in our patient revealed this combination, suggesting that the Capgras syndrome may be a form of reduplicative paramnesia with the same pathologic substrate.
Phantom limb phenomena are most often associated with amputations, although they may accompany many neurologic disorders. In the neurologic variety, expression of illusory limbs varies with the level at which the somesthetic pathway is interrupted, and with changes in consciousness. Phantom limb illusions are rarely reported in patients with multiple sclerosis (MS). The patient reported here complained of a supernumerary phantom limb during an exacerbation of MS. This case suggests that in neurologic diseases, phantom limb illusions may result from distorted perception of limbs that are subject to both sensory loss and such recurrent spontaneous sensations as paresthesias.
Amnesia is a common clinical problem characterized by four features: (1) normal immediate recall, (2) impaired ability to learn, (3) relatively spared ability to retrieve previously learned material, and (4) preserved cognitive and personality characteristics. Amnesia occurs as a distinct mental disorder, and nine variations seen clinically are described here: Korsakoff's psychosis, posttraumatic amnesia, amnesia stroke, postoperative amnesia, postinfectious amnesia, anoxic amnesia, transient global amnesia following ECT, and psychogenic amnesia. The clinical findings which characterize and differentiate these disorders are presented, along with suggestions for management and a discussion of the the outcome of amnesia.
A variety of alexia has been demonstrated that can be distinguished from the two classically recognized types of alexia. This reading disorder is seen in patients with a dominant frontal lobe pathologic condition that has produced a motor language disturbance (Broca aphasia) and is sufficiently disabling to deserve consideration as a variety of alexia. Functionally, the frontal reading disturbance differs from the other two types in that the patient comprehends meaningful content words better than relational or syntactic structures. Four factors that may underly frontal alexia have been noted: (1) gaze paresis, (2) inability to maintain verbal sequences; (3) inability to comprehend syntactic structure, and (4) literal alexia.
Confabulation consequent to organic amnesia is a well-described clinical finding. A number of plausible theories of confabulation have been proposed, but the various claims and counterclaims have not been systematically tested. A standardized test battery that included four different kinds of questions plus measures of suggestibility and the tendency to utilize external cues was administered to ten amnesic patients who demonstrated varying degrees of confabulation. One additional patient, whose clinical condition changed dramatically during his hospital course, received the battery on a number of occasions. Differences among patients were found in overall performance, degree of confabulation, and ability to use cues. Hypothesized relationships between confabulation and suggestibility, degree of memory disorder, and degree of disorientation were not confirmed. However, confabulation proved to be strongly related to the inability to withhold answers, to monitor one's own responses and to provide verbal self-corrections. These results suggest a tentative model of the process of confabulation as well as a number of useful clinical signs indicationg recovery from amnesia.
This report is based on the recorded experience of a patient with lability of emotional expression and other features of the syndrome of pseudobulbar palsy. We describe severe emotional overflow despite an underlying affective tone that is normal. In this context, emotional lability is a misnomer. "Hyperactive emotional reflexes" would be a more appropriate descriptive term, as the underlying mood appears normal, and only the degree of emotional expression is pathological.
The anatomical basis of memory disorder related to lesions of the diencephalon is a controversial matter. A study of a patient who developed severe amnesia in association with bilateral metastatic tumour invasion of the medial and posterior thalamus is reported. The findings in this case have led to further discussion of this unsettled issue.