Anosognosia and asomatognosia during intracarotid amobarbital inactivation.

BACKGROUND: Anosognosia (i.e., denial of hemiparesis) and asomatognosia (i.e., inability to recognize the affected limb as one's own) occur more frequently with right cerebral lesions. However, the incidence, relative recovery, and underlying mechanisms remain unclear. METHODS: Anosognosia and asomatognosia were examined in 62 patients undergoing the intracarotid amobarbital procedure as part of their preoperative evaluation for epilepsy surgery. Additional questions were asked in the last 32 patients studied. RESULTS: During inactivation of the non-language-dominant cerebral hemisphere, 88% of the 62 patients were unaware of their paralysis, and 82% could not recognize their own hand at some point. Only 3% did not exhibit anosognosia or asomatognosia. In general, asomatognosia resolved earlier than anosognosia. When patients could not recognize their hand, they uniformly thought that it was someone else's hand. Dissociations in awareness were seen in the second series of 32 patients. Although 23 patients (72%) thought that both arms were in the air, 31% pointed to the correct position of the paralyzed arm on the table. Despite the inability of 24 of 32 patients (75%) to recognize their own hand, 21% of these patients were aware that their arm was weak, and 38% had correctly located their paralyzed arm on the angiography table. CONCLUSIONS: Anosognosia and asomatognosia are both common during acute dysfunction of the non-language-dominant cerebral hemisphere. Dissociations of perception of location, weakness, and ownership of the affected limb are frequent, as are misperceptions of location and body part identity. The dissociations suggest that multiple mechanisms are involved.

Treatment of dementia-associated agitation with gabapentin.

The authors describe the use of gabapentin in the treatment of 4 outpatients with dementia-associated agitation. On the basis of clinical case reports and the Overt Agitation Severity Scale, all 4 patients had reduced agitation with gabapentin. Three of 4 patients were successfully titrated to a full dose of 2,400mg/day. These findings suggest a possible role for gabapentin in the behavioral management of patients with dementia.

Illusory limb movements in anosognosia for hemiplegia.

To clarify the relation between anosognosia for hemiplegia and confabulation, 11 patients with acute right cerebral infarctions and left upper limb hemiparesis were assessed for anosognosia for hemiplegia, illusory limb movements (ILMs), hemispatial neglect, asomatognosia, and cognitive impairment. Five of 11 patients had unequivocal confabulation as evidenced by ILMs. The presence of ILMs was associated with the degree of anosognosia (p = 0.002), with hemispatial neglect (p<0.05), and with asomatognosia (p<0.01). The results confirm that a strong relation exists between anosognosia for hemiplegia and confabulations concerning the movement of the plegic limb. There is also a strong relation between ILMs and asomatognosia.

Multiple fregoli delusions after traumatic brain injury.

A 61 year old man after a traumatic brain injury resulting in right frontal and left temporoparietal contusions developed florid Fregoli-type misidentifications. Extensive neuropsychological testing demonstrated significant deficits in executive and memory functions. The patient's neuropsychological profile closely resembled that seen in previously reported patients with Capgras syndrome. Our findings are consistent with the hypothesis that a combination of executive and memory deficits may account for cases of delusional misidentification associated with brain lesions. However, the form which the delusion takes may be influenced by other factors including motivation.

Partial status epilepticus associated with asomatognosia and alien hand-like behaviors [corrected].

BACKGROUND: Paroxysmal alien hand syndrome (AHS) has been reported in association with ictal phenomena, but simultaneous electroencephalographic verification has not been made. OBSERVATION: A 61-year-old woman with a right hemisphere glioblastoma multiforme developed movements of the left hand that she claimed were not under her control, and she denied ownership of the affected limb. Simultaneous electroencephalograms documented continuous spikes in the right frontotemporal region. Intravenous diazepam therapy (2.5 mg) reversed both the abnormal movements and the spike activity on the electroencephalograms. CONCLUSIONS: Our case demonstrates that partial seizures can produce AHS along with asomatognosia. This variety of AHS appears to be different, both etiologically and phenomenologically, from other forms of AHS.

Delusional misidentification in association with parkinsonism.

The delusional misidentification syndrome (DMS) has been associated with a range of neurological conditions. Three cases of DMS in patients with Parkinson's disease and dementia, treated with dopaminergic medications, are presented. It is postulated that DMS associated with parkinsonism results from a combination of dopaminergic psychosis and cognitive dysfunction involving the frontal lobe in particular. DMS in the setting of parkinsonism may be more frequent than commonly supposed.

The irreducible perspectives of consciousness.

I argue that there is no mind-brain problem but rather that there are irreducible subjective-objective problems. These include the difference between "inside" and "outside" perspectives on neural states, the creation of subjective neural states with objectified outside objects, and awareness of the self as an object in the world. The origin of consciousness is traced to the development of meaning states, and I demonstrate how differing perspectives related to these states are mutually irreducible. For instance, neural states are spatiotemporally distributed when observed from the outside, while mental states are unified when experienced from the inside; from the inside neural states are experienced as outside of themselves; and qualia have a material reality only from the inside. Rather than positing a special substance or immaterial process theory of consciousness, it is argued that the apparent immateriality of mind is an artifact of the nature of the phenomenon and of the process of observation itself.

Some interesting perturbations of the self in neurology.

In this review I discuss four neurological disorders that involve alterations of the self or self-awareness. These include the allen hand syndrome, asomatognosia, misidentification of the self in the mirror, and personal confabulation. In one way or another all of these inform us about the neurobiological basis of the self. It is suggested that mirror self-misidentification, asomatognosia, and personal confabulation are related syndromes. They are interpreted as examples of a perturbation in relatedness between the self and the environment related to delusional misidentification syndromes. The particular role of bilateral frontolimbic damage in producing disturbances of the self is discussed.

Consciousness of perception after brain damage.

Disturbances of visual perception after brain damage provide clues to understanding consciousness and the brain. In this article we review six visual disorders in which perception and consciousness are dissociated as a result of brain damage: blindsight, implicit shape perception in apperceptive visual agnosia, covert recognition of faces in prosopagnosia, unconscious perception in neglect and extinction, implicit reading in pure alexia, and implicit object recognition in associative visual agnosia. We consider these six disorders from the standpoint of three main schools of thought concerning consciousness and the brain, namely a localized system for consciousness, consciousness as a state of integration, and consciousness as a property of graded representation. The findings suggest that these syndromes do not share a single mechanism and that it is conceivable that more than one explanation will be necessary both within and across syndromes. We conclude on the basis of the current evidence that it is unlikely that any single brain system is necessary for conscious awareness of perception that does not play a role in perception as well.

Knowledge, implicit knowledge and metaknowledge in visual agnosia and pure alexia.

Residual or implicit knowledge has been observed in patients with object agnosia, optic aphasia and pure alexia. Previous investigators have considered implicit knowledge in these patients to be dissociated from awareness on the basis of intact semantic capabilities that are consistent with right hemisphere processing. The absence of explicit verbal identification is presumably dependent upon damaged left hemisphere systems. We describe a 72-year-old woman with a left occipital infarction, object agnosia and pure alexia who was unable to explicitly identify visual stimuli (objects and words), but was able to make reliable judgements of her residual knowledge on forced-choice matching tasks. While the patient could not consistently demonstrate awareness of knowledge prior to stimulus matching ('Do you know what this is?'), she was able to reliably demonstrate awareness of knowledge for response accuracy ('Are you sure?') assessed after stimulus matching. Further, the extent of the patient's metaknowledge corresponded to her degree of preserved knowledge. We propose that this pattern of performance suggests limited or partial access to preserved semantic knowledge which, though degraded, is not 'non-conscious'.

Neuropsychiatric evaluation in an outpatient setting.

In a retrospective case review of 336 outpatients who underwent neuropsychiatric evaluations, patients were sorted into five groups: 1) atypical psychiatric; 2) atypical neurological; 3) prior psychiatric/new-onset neurological; 4) prior neurological/new-onset psychiatric; 5) dementia versus pseudodementia. Cluster analysis of 19 presenting complaints differentiated among groups. Post-consultation changes in preconsultation diagnosis occurred frequently overall, with more new case finding for psychiatric than for neurological disorders. For example, mood disorder diagnoses increased from 7.7% to 16.1%. Overall, dementia was the most common postconsultation diagnosis (32.8%). The authors conclude that suspicion for dementia should be high in neuropsychiatric referrals and that mood disorders may be especially common in neuropsychiatric patients.

Associative visual agnosia and alexia without prosopagnosia.

Disagreement over the neuroanatomical substrate of associative visual agnosia encompasses such basic issues as: (1) the necessity for bilateral lesions; (2) the intrahemispheric locus of damage; and (3) the roles of disconnection versus cortical damage. We examined three patients whose associative visual agnosia encompassed objects and printed words but spared faces. CAT scans revealed unilateral dominant occipitotemporal strokes. CAT scans of four previously reported cases with this same profile of associative agnosia were obtained. Dominant parahippocampal, fusiform and lingual gyri were the most extensively damaged cortical regions surveyed and were involved in all cases. Of white matter tracts surveyed, only temporal white matter including inferior longitudinal fasciculus was severely and universally involved. Splenium of the corpus callosum was frequently but not always involved. We conclude there is a form of associative visual agnosia with agnosia for objects and printed words but sparing face recognition which has a characteristic unilateral neuropathology. Damage or disconnection of dominant parahippocampal, fusiform and lingual gyri is the necessary and sufficient lesion.

Anosognosia and visuoverbal confabulation.

OBJECTIVE: To examine the relationship between verbal confabulation and anosognosia for hemiplegia (AHP). DESIGN: We compared patients with right hemisphere lesions and AHP with a control group with right hemisphere lesions without anosognosia. Patients attempted visual identifications of objects exposed to the left hemifield with brief (condition 1) or prolonged (condition 2) presentations. Responses were recorded as correct, incorrect, or admission of failure to perceive. SETTING: Inpatients at Beth Israel Medical Center, New York, NY. PATIENTS: A consecutive sample of nine patients with right hemisphere infarcts who demonstrated left hemiparesis, extrapersonal neglect, and left-sided visual field defects. MAIN OUTCOME MEASURES: Rates of correct, incorrect, and admission of failure to perceive responses. RESULTS: Patients with AHP had higher error rates (confabulations) and lower admission of failure to perceive rates than nonanosognosic patients in condition 1. Patients with AHP continued to have higher error rates in condition 2. Nonanosognosic patients had higher correct rates in condition 2 than condition 1. Groups did not differ in degree of neglect, lesion size or location, atrophy, sensory loss, or disorientation. CONCLUSION: Verbal confabulation is an important determinant in anosognosia.

Two alien hand syndromes.

Review of the clinical characteristics and neuroanatomy of 20 reported cases of alien hand syndrome (AHS) and a patient of our own confirm that AHS is actually two distinct syndromes. Frontal AHS occurs in the dominant hand; is associated with reflexive grasping, groping, and compulsive manipulation of tools; and results from damage to the supplementary motor area, anterior cingulate gyrus, and medial prefrontal cortex of the dominant hemisphere and anterior corpus callosum. Callosal AHS is characterized primarily by intermanual conflict and requires only an anterior callosal lesion. the occurrence of frontal AHS in the dominant limb can be explained by an increased tendency for dominant limb exploratory reflexes coupled with release from an asymmetrically distributed, predominant nondominant-hemisphere inhibition. Callosal AHS is best explained by hemispheric disconnection manifested during behaviors requiring dominant-hemisphere control.

Diagnostic tests for choreoacanthocytosis.

Two patients with striatal atrophy and a clinical syndrome consistent with choreoacanthocytosis had normal dried blood smears but their red cells demonstrated an abnormal sensitivity to various conditions known to promote discocyte-echinocyte transformation. Dilution in normal saline, in vitro aging, and contact with glass caused a great proportion of these patients' red cells to develop multiple spiny or rounded projections. Under identical conditions, such shape changes did not occur in normal patients or in those with Huntington's disease. Scanning electron microscopy showed that the age-induced increase in acanthocytic-appearing cells could be reversed with chlorpromazine. These data suggest that the red cells from these patients with striatal degeneration are deficient in their ability to preserve normal shape in the face of echinocytic stress and that this observation has diagnostic and, possibly, pathophysiologic significance.

Verbal asomatognosia.

Verbal asomatognosia is a form of neglect in which a patient denies ownership of a limb contralateral to a brain lesion. To establish the neuroanatomic substrate of this syndrome, we analyzed the CTs of 12 right-hemisphere stroke patients with neglect and verbal asomatognosia and 4 patients with neglect but without asomatognosia. Of 16 cortical and subcortical brain regions analyzed, supramarginal gyrus and its subcortical connections within posterior corona radiata were most consistently involved in the asomatognosia cases. One or both of these regions were spared in all cases of neglect without asomatognosia. Our data confirm Nielsen's localization of asomatognosia to the right supramarginal gyrus and thalamoparietal peduncle. Converging lines of evidence from experiments in humans and monkeys suggest that damage to area PF may be necessary for the production of personal neglect of a limb.

Ipsilateral extinction in the hemineglect syndrome.

Data suggest right-hemisphere dominance for attention. Right-hemisphere lesions reduce attentional capacity that may manifest as neglect or extinction. Attention can be assessed with the Face-Hand Test where touch on the face may extinguish simultaneous touch on the hand. Extinction ipsilateral to unilateral lesions suggests abnormal attention to ipsilateral hemispace. We tested patients with left- and right-hemisphere lesions without neglect and right-hemisphere lesions with neglect with stimuli applied exclusively ipsilateral to lesions. In experiment 1, stimuli were applied in face-hand combinations. In experiment 2, the Face-Hand Test was ranked from 0 (no extinction) to 7 (marked extinction) using progressively greater stimulation. In both experiments, right-hemisphere patients with neglect made significantly more errors than left-hemisphere patients without neglect. These data support models of bidirectional right-hemisphere attentional dominance.

'Inner speech' in conduction aphasia.

It has been suggested by Kurt Goldstein, MD, that conduction aphasia is a disturbance of "inner speech." We tested this hypothesis in five patients who had conduction aphasia with similar speech disturbances. The patients were presented with pictures and were required to perform, without overt vocalization, comparisons of word length and homophonic and rhyming matches. Four patients successfully performed such judgments on words they could not vocalize, but one patient could not. These findings suggest that the hypothesis may have been correct for only a subgroup of conduction aphasics. The findings also provide evidence for heterogeneity within the class of conduction aphasia.

Multimodal agnosia after unilateral left hemisphere lesion.

Agnosia is an abnormality of recognition that is not explained by sensory or cognitive disorders. We studied a patient who had combined visual-tactile agnosia without prosopagnosia after a left hemisphere infarct. Although he copied figures presented visually and he performed intramodal or crossmodal visual-tactile matches, he could not indicate recognition by either sight or touch. The lesion involved areas of the occipital and temporal lobes that may be important for human performance of tasks that require construction and application of meaning to percepts presented both visually and tactually.