Progressive supranuclear palsy: a survey of the disease course

BACKGROUND

The most accurate knowledge about progressive supranuclear palsy (PSP) comes from small sample studies that preclude precise estimation of the proportion of PSP patients affected with various symptoms and the examination of factors predicting survival time.

OBJECTIVE

To describe the course of PSP in a large clinically diagnosed sample of PSP patients and to identify factors predicting survival time.

METHODS

We surveyed the caregivers of 318 living and 119 deceased patients with progressive supranuclear palsy. The main outcome measures were a principal symptom severity questionnaire and a signs and symptoms questionnaire.

RESULTS

The estimated age of PSP symptom onset depends critically on how symptom onset is defined, with estimates differing by as much as 1.5 years. Men and women were represented equally (51.6% versus 48.4%) in the living sample, but men formed 61.8% of the deceased sample. Men were diagnosed later than women following symptom onset (33.4 versus 24.1 months) and died earlier following the diagnosis (37.0 versus 47.6 months). Motor and visual symptoms appeared first, followed by emotional and personality problems, cognitive impairment, and sleep changes. Whereas motor symptoms eventually affected almost every patient, emotional/personality and cognitive symptoms did not. The early onset, presence of falls, slowness, and inability to move eyes downward early in the development of the disease predicted survival time.

CONCLUSION

PSP is a rapidly progressive disease dominated by motor symptoms, and it affects men more frequently than women.

Overestimation and unreliability in "feeling-of-doing" judgements about temporal ordering performance: impaired self-awareness following frontal lobe damage

"Feeling-of-doing" accuracy in a temporal ordering task in 33 patients with frontal lobe lesions and a matched control group was investigated. The temporal ordering task used word lists that had high, medium, or no semantic interrelatedness. Patients with frontal lobe lesions showed an impairment in temporal ordering across all three word lists. Both groups performed better on the lists with higher semantic interrelatedness. Patients with frontal lobe lesions overestimated their ability to order words accurately. On the less semantically interrelated lists, metamemory judgment in patients with frontal lesions did not correlate with their performance. These results indicate that both temporal order judgment and metacognitive decisions about temporal order judgment are subserved by the prefrontal cortex and further clarifies the role of the frontal lobes in behavioral monitoring.

Linguistic processing during repetitive transcranial magnetic stimulation

To determine if linguistic processing could be selectively disrupted with repetitive transcranial magnetic stimulation (rTMS), rTMS was performed during a picture-word verification task. Seven right-handed subjects were trained in two conditions: picture-word verification, which required the subject to verify whether the picture of an object matched the subtitle name on the same page, and frame verification, which required subjects to verify whether there was a rectangular frame around the combined object picture and subtitle. Half of the trials were performed during rTMS. The effects of rTMS on performance were evaluated at the following four scalp positions: left anterior (the area where rTMS produced speech arrest), a mirror site on the right, and two positions in the left and right parietal region. Stimulation over the left deltoid muscle served as a control. Subjects had less difficulty in making picture-word matching decisions during unstimulated compared with stimulated trials at the left anterior and posterior positions. No significant difference in accuracy was detected in the frame verification condition, but response times in the frame verification condition were longer with stimulation at the left anterior position. Because rTMS of the dominant hemisphere affected linguistic processing independent of speech motor output, we confirm that rTMS may be used to investigate language and other cognitive functions.

Executive functions in multiple sclerosis: an analysis of temporal ordering, semantic encoding, and planning abilities

Previous studies have consistently demonstrated impairments in conceptual reasoning and set-shifting abilities in patients with multiple sclerosis (MS). Other executive functions have been less frequently examined. We compared 44 MS patients and 48 demographically matched controls on a temporal-ordering and semantic-encoding task and on a test of planning (Tower of Hanoi). Compared with controls, MS patients experienced deficient semantic encoding and planning but unimpaired temporal-order memory. For both tasks, post hoc analyses indicated that chronic-progressive MS patients contributed most to the group differences. A combination of poor planning and slowed information-processing speed was hypothesized to have contributed to MS patients' impaired Tower of Hanoi performance. Further research is needed to explore the possible relationship between semantic-encoding and planning deficits in MS and social and occupational disabilities.

Patients with chronic fatigue syndrome and accurate feeling-of-knowing judgments

Many Chronic Fatigue Syndrome (CFS) patients complain of memory impairments which have been difficult to document empirically. Subjective complaints of memory impairment may be due to a deficit in metamemory judgment. CFS patients and matched controls were tested with a computerized Trivia Information Quiz that required them to rate their confidence about correctly recognizing an answer in a multiple choice format that they had been unable to remember in a fact-recall format. Even though CFS patients reported significantly greater amounts of fatigue, cognitive, and physical symptoms, the accuracy of their confidence levels and recognition responses were similar to controls. This finding suggests that a metamemory deficit is not the cause of the memory problems reported by CFS patients.

A study of the performance of patients with frontal lobe lesions in a financial planning task

It has long been argued that patients with lesions in the prefrontal cortex have difficulties in decision making and problem solving in real-world, ill-structured situations, particularly problem types involving planning and look-ahead components. Recently, several researchers have questioned our ability to capture and characterize these deficits adequately using just the standard neuropsychological test batteries, and have called for tests that reflect real-world task requirements more accurately. We present data from 10 patients with focal lesions to the prefrontal cortex and 10 normal control subjects engaged in a real-world financial planning task. We also introduce a theoretical framework and methodology developed in the cognitive science literature for quantifying and analysing the complex data generated by problem-solving tasks. Our findings indicate that patient performance is impoverished at a global level but not at the local level. Patients have difficulty in organizing and structuring their problem space. Once they begin problem solving, they have difficulty in allocating adequate effort to each problem-solving phase. Patients also have difficulty dealing with the fact that there are no right or wrong answers nor official termination points in real-world planning problems. They also find it problematic to generate their own feedback. They invariably terminate the session before the details are fleshed out and all the goals satisfied. Finally, patients do not take full advantage of the fact that constraints on real-world problems are negotiable. However, it is not necessary to postulate a 'planning' deficit. It is possible to understand the patients' difficulties in real world planning tasks in terms of the following four accepted deficits: inadequate access to 'structured event complexes', difficulty in generalizing from particulars, failure to shift between 'mental sets', and poor judgment regarding adequacy and completeness of a plan.

Executive functions in multiple sclerosis: an analysis of temporal ordering, semantic encoding, and planning abilities

Previous studies have consistently demonstrated impairments in conceptual reasoning and set-shifting abilities in patients with multiple sclerosis (MS). Other executive functions have been less frequently examined. We compared 44 MS patients and 48 demographically matched controls on a temporal-ordering and semantic-encoding task and on a test of planning (Tower of Hanoi). Compared with controls, MS patients experienced deficient semantic encoding and planning but unimpaired temporal-order memory. For both tasks, post hoc analyses indicated that chronic-progressive MS patients contributed most to the group differences. A combination of poor planning and slowed information-processing speed was hypothesized to have contributed to MS patients' impaired Tower of Hanoi performance. Further research is needed to explore the possible relationship between semantic-encoding and planning deficits in MS and social and occupational disabilities.

Modality-specific processing streams in verbal working memory: evidence from spatio-temporal patterns of brain activity

The present study was concerned with whether there are separate, modality-specific processing "streams" in verbal working memory for information that is heard or read. We used event-related brain potentials (ERPs) recorded from scalp of normal humans to show between-modality differences in spatio-temporal patterns of brain activity during retention in working memory of aurally or visually presented verbal information. The ERP patterns suggested that a sustained, automatically maintained auditory store was activated by auditory presentation and a transient, visual-verbal store was activated by visual presentation. In addition to these modality-specific differences, the ERPs indicated that the phonological loop was activated in both modalities and further suggested that the onset of phonological loop activation was earlier for auditory presentation.

A restricted 'spotlight' of attention in visual object recognition

We describe a patient (NJ), with a progressive visual disturbance, who showed an impairment in identifying larger visually-presented objects relative to their smaller counterparts. NJ showed this size effect for line drawings of objects, words and single letters. When presented with large letters comprised of smaller letters and asked to give speeded identification responses to either the large or small letters, NJ was grossly impaired at identifying the large letter. Additionally, when presented with a context meant to bias responding to either the large or small letter, NJ showed faster and more accurate responding in the small direction, but not in the large direction. We interpret these results as indicative of an impaired 'spotlight' of attention, which is deployed across the visual array, and is necessary for providing the selective visual attention responsible for the integration of visual features.

Frontal and parietal networks for conditional motor learning: a positron emission tomography study

Studies on nonhuman primates show that the premotor (PM) and prefrontal (PF) areas are necessary for the arbitrary mapping of a set of stimuli onto a set of responses. However, positron emission tomography (PET) measurements of regional cerebral blood flow (rCBF) in human subjects have failed to reveal the predicted rCBF changes during such behavior. We therefore studied rCBF while subjects learned two arbitrary mapping tasks. In the conditional motor task, visual stimuli instructed which of four directions to move a joystick (with the right, dominant hand). In the evaluation task, subjects moved the joystick in a predetermined direction to report whether an arrow pointed in the direction associated with a given stimulus. For both tasks there were three rules: for the nonspatial rule, the pattern within each stimulus determined the correct direction; for the spatial rule, the location of the stimulus did so; and for the fixed-response rule, movement direction was constant regardless of the pattern or its location. For the nonspatial rule, performance of the evaluation task led to a learning-related increase in rCBF in a caudal and ventral part of the premotor cortex (PMvc, area 6), bilaterally, as well as in the putamen and a cingulate motor area (CM, area 24) of the left hemisphere. Decreases in rCBF were observed in several areas: the left ventro-orbital prefrontal cortex (PFv, area 47/12), the left lateral cerebellar hemisphere, and, in the right hemisphere, a dorsal and rostral aspect of PM (PMdr, area 6), dorsal PF (PFd, area 9), and the posterior parietal cortex (area 39/40). During performance of the conditional motor task, there was only a decrease in the parietal area. For the spatial rule, no rCBF change reached significance for the evaluation task, but in the conditional motor task, a ventral and rostral premotor region (PMvr, area 6), the dorsolateral prefrontal cortex (PFdl, area 46), and the posterior parietal cortex (area 39/40) showed decreasing rCBF during learning, all in the right hemisphere. These data confirm the predicted rCBF changes in premotor and prefrontal areas during arbitrary mapping tasks and suggest that a broad frontoparietal network may show decreased synaptic activity as arbitrary rules become more familiar.

Event-related desynchronization (ERD) in the alpha frequency during development of implicit and explicit learning

To understand the role of the motor cortex in implicit and explicit learning, we studied alpha event-related desynchronization (ERD) while 13 right-handed individuals performed a variation of the serial reaction time task (SRTT). EEG signals were recorded simultaneously from 29 scalp locations and the ERD was computed. During data collection, all subjects developed implicit knowledge, demonstrated by shortening of the response time, and explicit knowledge of the test sequence. The average ERD maps of all 13 subjects demonstrated that during the initial learning, there was a decline in alpha band power that was maximal over the contralateral central region. The ERD reached a transient peak amplitude at a point when the subjects attained full explicit knowledge, and diminished subsequently. The transient peak in ERD was highly significant at C3. These electrophysiologic findings support previous studies which have demonstrated that motor activity changes as behavior changes over the course of learning.

PET imaging of maze processing

Covered maze traversal models nonverbal planning, involving sequential execution of moves using learned spatial maps. To determine the neural substrate involved in maze processing, eleven adults underwent [H(2)15O]-PET while performing motor control, following the computer; visual control, choosing the wall with more dead-ends; uncovered maze, traversing fully visible mazes; covered maze, traversing mazes only locally visible. Maze processing lateralizes to the right hemisphere: uncovered maze versus controls revealed area 23 and 29 activation; covered maze versus controls activated areas 8, 10 and 19. The extrastriate region may store path information, evoked by prefrontal areas for spatial planning and navigation.

Multiple visuospatial working memory buffers: evidence from spatiotemporal patterns of brain activity

Numerous studies have shown that the visual system involves different cortical pathways in the perception of object (ventral visual pathway) and spatial (dorsal visual pathway) information. The present study was concerned with whether human visuospatial working memory divides along similar lines. We used event-related brain potentials (ERPs) recorded from scalp of normal humans to show the existence of different buffering systems for the retention of object and spatial visual information. Subjects were presented with object or spatial stimuli to be retained for a 3.6-sec interval. The ERPs isolated brain activity associated with retention from earlier storage and later retrieval processes. The ERP scalp topographies indicated that the underlying patterns of brain activation were different during retention of object and spatial information.

Sustained attention deficits in patients with right frontal lesions

Patients with frontal lobe lesions were compared to controls matched for age and education on several tests of sustained attention. One was a simple reaction time task requiring subjects to respond whenever they saw an "X', one was a Continuous Performance Test that required subjects to respond to an "X' but refrain from responding to other letters, and one involved reading a story and responding to a specified target. Patients with right frontal lesions showed longer RTs and missed more targets than control subjects for all three tests. In addition, right frontal patients got worse with time on the CPT. These results suggest a special role for the right frontal lobe in sustaining attention over time.

Use and safety of a new repetitive transcranial magnetic stimulator

In order to test a new repetitive transcranial magnetic stimulator, the Dantec MagPro, we administered transcranial magnetic stimulation (TMS) at 1 Hz and 125% of motor threshold for an average of 204 s (until the coil temperature reached 40 degrees C) and 20 Hz stimulation at 100% of motor threshold for 2 s every minute for 10 min, on different days to 10 healthy volunteers. We stimulated 6 scalp positions (primary motor area (M1) and sites 5 cm anterior and posterior on each hemisphere) with an 8-shaped coil. We tested immediate and delayed memory, verbal fluency, prolactin levels and EEG at the beginning of the study and after stimulation on each day. No abnormalities were found. Motor evoked potentials evoked with 1 Hz stimulation diminished progressively in amplitude, and 1 Hz stimulation of M1 caused inhibition lasting at least 1 min in 3 of 4 subjects who were tested with 0.1 Hz stimulation before and after the 1 Hz stimulation period. This did not occur with 20 Hz stimulation. Finger tapping frequency was tested at the beginning of the study and after TMS at each scalp site. Finger tapping rate data from 6 additional subjects who were stimulated in an identical fashion with a different stimulator were also analyzed. There was an increase in tapping rate after TMS which was independent of scalp site. This was most pronounced with 1 Hz stimulation at 125% of threshold and reached statistical significance in the hand contralateral to the stimulation. The results of this study indicate that rTMS with the MagPro stimulator is safe at specific combinations of intensity, frequency and train duration.

Preserved cognitive processes in cerebellar degeneration

Aspects of cognitive processing in patients with cerebellar degeneration (CD) were studied in order to examine the validity of recent findings that CD patients demonstrate deficits in visuospatial cognition and verbal-associative learning. Two groups of patients with CD were compared to stratified matched control groups on tests examining selective visual attention, visual spatial attention, mental rotation of geometric designs, and memory for the temporal order of words they were previously exposed to. CD patients performed similarly to their matched controls across all tasks. These results indicate that the reported cognitive deficits of CD patients are quite selective and need further specification in order to more fully describe their relationship to cerebellar dysfunction.

Perceptual timing in cerebellar degeneration

This study examined time perception in 12 patients with cerebellar degeneration (CD) and in 13 normal controls (NC). We used a time bisection procedure with four interval conditions (100-900 msec; 8-32 sec; 100-600 msec; 100-325 msec). Each subject's bisection point, discrimination ability (the Weber ratio) and precision (the inverse of the proportion of unexplained variance) was calculated for each condition. CD patients' performance on the 100-900 msec time bisection condition suggested a possible time discrimination deficit, which was confirmed with intervals in the range of 100-600 msec. Time discrimination was normal on the 100-325 msec condition and impaired on the 8-32 sec bisection task. However, when discriminating long intervals, CD patients also showed a precision deficit, which points to impaired sustained attention and/or decision processes. Our findings corroborate the view that cerebellar timing processes are not limited to the motor system but are also used in perceptual computations.

Clinical research criteria for the diagnosis of progressive supranuclear palsy (Steele-Richardson-Olszewski syndrome): report of the NINDS-SPSP international workshop

To improve the specificity and sensitivity of the clinical diagnosis of progressive supranuclear palsy (PSP, Steele-Richardson-Olszewski syndrome), the National Institute of Neurological Disorders and Stroke (NINDS) and the Society for PSP, Inc. (SPSP) sponsored an international workshop to develop an accurate and universally accepted set of criteria for this disorder. The NINDS-SPSP criteria, which were formulated from an extensive review of the literature, comparison with other previously published sets of criteria, and the consensus of experts, were validated on a clinical data set from autopsy-confirmed cases of PSP. The criteria specify three degrees of diagnostic certainty: possible PSP, probable PSP, and definite PSP. Possible PSP requires the presence of a gradually progressive disorder with onset at age 40 or later, either vertical supranuclear gaze palsy or both slowing of vertical saccades and prominent postural instability with falls in the first year of onset, as well as no evidence of other diseases that could explain these features. Probable PSP requires vertical supranuclear gaze palsy, prominent postural instability, and falls in the first year of onset, as well as the other features of possible PSP. Definite PSP requires a history of probable or possible PSP and histopathologic evidence of typical PSP. Criteria that support the diagnosis of PSP, and that exclude diseases often confused with PSP, are presented. The criteria for probable PSP are highly specific, making them suitable for therapeutic, analytic epidemiologic, and biologic studies, but not very sensitive. The criteria for possible PSP are substantially sensitive, making them suitable for descriptive epidemiologic studies, but less specific. An appendix provides guidelines for diagnosing and monitoring clinical disability in PSP.

The effects of frontal lobe damage on everyday problem solving

The prefrontal cortex plays an especially important role in human social-cognitive behavior. It has been difficult to quantify deficits in this domain in patients with frontal lobe lesions using standardized psychological instruments. We administered the Everyday Problem Solving Inventory (EPSI), which is composed of a range of scenarios depicting everyday social problems and their possible solutions, to a group of patients with frontal lobe lesions who were required to rate each of 4 possible solutions to each problem for their effectiveness. Our sample consisted of 27 normal controls (NCs), 33 patients with focal frontal lobe lesions (FLL), and 3 patients with frontal lobe dementia (FLD). The performance of the FLL patients on the EPSI instrument was also compared with their performance on traditional neuropsychological tests. The results indicated that the FLD patients' EPSI rank ordering of social problem solutions was uncorrelated with the performance of NCs and about half of the FLL patients EPSI rank orderings of solutions also varied substantially from those of the NCs. These same FLL patients also had the lowest scores, compared to FLL patients whose judgements on the EPSI were similar to that of the NCs, on a set of neuropsychological tasks sensitive to frontal lobe dysfunction. There was no obvious relationship between locus of lesion within the frontal lobes and performance on the EPSI. These results suggest that some patients with prefrontal lobe lesions may have impaired social judgement that can be directly revealed through the use of a conventional psychological inventory such as the EPSI.

Encoding of sequence and boundaries of scripts following prefrontal lesions

Script analysis was investigated in patients with lesions in the prefrontal (n = 10) and posterior (n = 8) cortical regions, and in normal subjects (n = 15). The selection and temporal organization of relevant actions belonging to different pre-established sequences were studied in three different situations: (A) script with headers, (B) script with headers and distractors, and (C) scripts without headers. Contrarily to Normals and Posterior patients, Frontal patients committed sequence and boundary errors, and failed to eliminate distractors elements. The analysis of errors suggests two different cognitive modes of representing actions: (1) One using temporal contiguity between actions, that would be mainly under the control of the posterior associative areas; (2) the other, using the goal of the action and its consequences as a binding element between script and context, that would require the intervention of prefrontal cortex.

Frontal lobe injuries, violence, and aggression: a report of the Vietnam Head Injury Study

Knowledge stored in the human prefrontal cortex may exert control over more primitive behavioral reactions to environmental provocation. Therefore, following frontal lobe lesions, patients are more likely to use physical intimidation or verbal threats in potential or actual confrontational situations. To test this hypothesis, we examined the relationship between frontal lobe lesions and the presence of aggressive and violent behavior. Fifty-seven normal controls and 279 veterans, matched for age, education, and time in Vietnam, who had suffered penetrating head injuries during their service in Vietnam, were studied. Family observations and self-reports were collected using scales and questionnaires that assessed a range of aggressive and violent attitudes and behavior. Two Aggression/Violence Scale scores, based on observer ratings, were constructed. The results indicated that patients with frontal ventromedial lesions consistently demonstrated Aggression/Violence Scale scores significantly higher than controls and patients with lesions in other brain areas. Higher Aggression/Violence Scale scores were generally associated with verbal confrontations rather than physical assaults, which were less frequently reported. The presence of aggressive and violent behaviors was not associated with the total size of the lesion nor whether the patient had seizures, but was associated with a disruption of family activities. These findings support the hypothesis that ventromedial frontal lobe lesions increase the risk of aggressive and violent behavior.