Frédéric Assal

Stops walking when talking: a predictor of falls in older adults?

The objective of this study was to systematically review all published articles examining the relationship between the occurrence of falls and changes in gait and attention‐demanding task performance whilst dual tasking amongst older adults. An English and French Medline and Cochrane library search ranging from 1997 to 2008 indexed under ‘accidental falls’, ‘aged OR aged, 80 and over’, ‘dual task’, ‘dual tasking’, ‘gait’, ‘walking’, ‘fall’ and ‘falling’ was performed. Of 121 selected studies, fifteen met the selection criteria and were included in the final analysis. The fall rate ranged from 11.1% to 50.0% in retrospective studies and from 21.3% to 42.3% in prospective ones. Amongst the three retrospective and eight prospective studies, two and six studies, respectively, showed a significant relationship between changes in gait performance under dual task and history of falls. The predictive value for falling was particularly efficient amongst frail older adults compared with healthy subjects. Two prospective studies challenged the usefulness of the dual‐task paradigm as a significant predictor compared to single task performance and three studies even reported that gait changes whilst dual tasking did not predict falls. The pooled odds ratio for falling was 5.3 (95% CI, 3.1–9.1) when subjects had changes in gait or attention‐demanding task performance whilst dual tasking. Despite conflicting early reports, changes in performance whilst dual tasking were significantly associated with an increased risk for falling amongst older adults and frail older adults in particular. Description of health status, standardization of test methodology, increase of sample size and longer follow‐up intervals will certainly improve the predictive value of dual‐task‐based fall risk assessment tests.

Tolcapone and fulminant hepatitis

developed raised aminotransferase (more than three times the upper limit of normal). Elevations were found between 6 and 12 weeks after starting tolcapone and returned to baseline within weeks, with or without discontinuing the drug. These biological changes were not clearly dependent on the dose (seven patients in the 100 mg group vs nine patients in the 200 group). ALT was more often elevated than AST.

Gait analysis in demented subjects: Interests and perspectives

Gait disorders are more prevalent in dementia than in normal aging and are related to the severity of cognitive decline. Dementia-related gait changes (DRGC) mainly include decrease in walking speed provoked by a decrease in stride length and an increase in support phase. More recently, dual-task related changes in gait were found in Alzheimer’s disease (AD) and non-Alzheimer dementia, even at an early stage. An increase in stride-to-stride variability while usual walking and dual-tasking has been shown to be more specific and sensitive than any change in mean value in subjects with dementia. Those data show that DRGC are not only associated to motor disorders but also to problem with central processing of information and highlight that dysfunction of temporal and frontal lobe may in part explain gait impairment among demented subjects. Gait assessment, and more particularly dual-task analysis, is therefore crucial in early diagnosis of dementia and/or related syndromes in the elderly. Moreover, dual-task disturbances could be a specific marker of falling at a pre-dementia stage.

Gait variability among healthy adults : low and high stride-to-stride variability are both a reflection of gait stability

Background: It has been suggested that high stride-to-stride variability (STV) is a reflection of gait instability. However, both low and high STV has been shown in fallers and in nonfallers; therefore, the interpretation of STV of spatiotemporal gait parameters remains difficult. Thus, we sought to characterize and compare STV of spatial and temporal stride parameters among young and older healthy adults, and to determine the extent to which opposite results in STV could provide similar implications in terms of gait stability. Methods: Mean values of coefficients of variation of spatiotemporal gait parameters were collected from 30 young adults (14 men and 16 women; mean age 28.1 ± 6.0 years) and 33 older adults (2 men and 31 women; mean age 74.4 ± 7.1 years) walking at self-chosen normal walking speed over a GAITRite® System. Results: An age-related increase in STV was only observed with stride width (p = 0.012), whereas increased stride length and stance time variability in older adults were related to decreased walking speed (p = 0.006 and p = 0.018). In addition, both low and high STV was found in both groups of subjects and the highest value was observed for stride width (p < 0.001). Conclusion: The two main implications of the present results are that decreased walking speed should be taken into account when exploring age-related effects on gait variability, and that both low and high spatiotemporal STV may reflect gait stability in healthy adults.

Impact of impaired executive function on gait stability

Background: Executive dysfunction contributes to gait changes, but the precise mechanisms are still poorly understood. Dual-task-related gait changes depend in part on the capacity to appropriately allocate attention between tasks performed simultaneously and are mainly related to executive deficits. This study aimed to describe the impact of dysexecutive function on gait stability in subjects with dementia using dual tasking. Methods: Mean values and coefficients of variation of stride time while only walking and while walking and backward counting (dual tasking) were measured using the GAITRite® System in 18 subjects with dementia and impaired executive function (IEF), in 16 subjects with dementia and intact executive function, and in 22 nondemented subjects as controls. Results: Stride time, and particularly its variability, significantly increased while performing dual tasking (p < 0.05). IEF was related to both stride time and stride time variability during walking only and to even more gait changes, while dual tasking compared to nondemented subjects and demented subjects without IEF. Conclusions: These findings confirm the role of executive function in dual tasking, but also strongly suggest their importance for gait stability.

Imagined Timed Up & Go test: a new tool to assess higher-level gait and balance disorders in older adults?

BACKGROUND Few studies have explored motor imagery (MI) as a way of accessing the higher-level of control of complex body movements involved in gait or balance. The objective of this study was 1) to measure and compare the time needed to complete the Timed Up & Go test (TUG), the time needed to imagine performing the same test (iTUG) and to calculate the time difference between both of these conditions (delta time) in a sample of young and older adults, and 2) to examine whether there was an association between the Timed Up & Go test results (TUG, iTUG, delta time), age and cognitive decline. METHODS A total of 162 subjects (38 healthy young adults, mean age 25.7+/-2.3 years, 73.7% women and 124 older inpatients, mean age 85.3+/-6.5 years, 76.6% women) were included in this cross-sectional study. The mean+/-SD of TUG, iTUG and delta time, age and the Mini Mental State Examination (MMSE) score were used as main outcomes. RESULTS Age was associated with an increase in time of TUG (P<0.001) and of delta time (P=0.015), and with a decrease in time of iTUG (P<0.001), whereas cognitive decline was only associated with increase in delta time (P=0.030). There was an increase in time of TUG (P<0.001) and in delta time (P<0.001) for subjects who used a walking aid. The increase in delta time depended on the MMSE score when the subjects did not use a walking aid (P for trend=0.001). CONCLUSIONS iTUG is clinically feasible among frail older adults and may quickly inform any clinician about higher-level changes in control of gait and balance in older adults.

Severe but reversible encephalopathy associated with cefepime.

In this study, a report has been made of 19 cases of severe encephalopathy in patients with renal impairment who were treated during the last three years for various infections with cefepime, a new parenteral cephalosporin antibiotic. All patients (aged 57 to 91 years) presented a prolonged confusional state associated with diffuse rhythmic non-reactive triphasic sharp waves on the EEG. All the electroclinical symptomatology disappeared within 24-48 hours after discontinuation of drug administration. A clear relation was found between encephalopathy and cefepime intake. These observations underline the fact that the cefepime dosage should be reduced in renally impaired patients.

Moving with or without will: functional neural correlates of alien hand syndrome

Alien hand syndrome is a rare neurological disorder in which movements are performed without conscious will. By using functional magnetic resonance imaging in a patient with alien hand syndrome after right parietal lesion, we could identify brain regions activated during involuntary or voluntary actions with the affected left hand. Alien hand movements involved a selective activation of contralateral primary motor cortex (M1), presumably released from conscious control by intentional planning systems. By contrast, voluntary movements activated a distributed network implicating not only the contralateral right M1 and premotor cortex but also the left inferior frontal gyrus, suggesting an important role of the dominant hemisphere in organizing willed actions. Ann Neurol 2007

SPECT in periodic lateralized epileptiform discharges (PLEDs): a form of partial status epilepticus?

Periodic lateralized epileptiform discharges (PLEDs) are a well defined electroencephalographic entity but whether PLEDs represent an ictal condition or not remains debated. Much work has been done using electroencephalography (EEG) but new approaches using cerebral perfusion imaging may give more information about this question. We aimed to evaluate if PLEDs were associated with high regional cerebral blood flow (rCBF). We studied 18 patients with PLEDs and different pathologies, and performed brain single-photon-emission computed tomography (SPECT) during and, for three cases, after the disappearance of PLEDs. Qualitative variations and locations of rCBF were compared with PLEDs. Association with seizures and type of seizures were also assessed. SPECT showed high rCBF in 18/18 patients (100%). The location of PLEDs and high rCBF matched in 17/18 cases (94%). In the three cases where SPECT was performed after PLEDs disappeared, the high rCBF had cleared (100%). Eighteen cases (100%) presented seizures before recording of PLEDs, mainly motor (partial motor or generalized tonic-clonic). Where there was a decreased rCBF (related to a lesion) there was little relationship to PLEDs and all patients with decreased rCBF had an adjacent increased rCBF. These results confirm preliminary case reports. Hyperperfusion adds further to the argument that PLEDs may be related to a form of partial status epilepticus.

The Neural Basis of Age-Related Changes in Motor Imagery of Gait: An fMRI Study

BACKGROUND Aging is often associated with modifications of gait. Recent studies have revealed a strong relationship between gait and executive functions in healthy and pathological aging. We hypothesized that modification of gait due to aging may be related to changes in frontal lobe function. METHODS Fourteen younger (27.0±3.6 years) and 14 older healthy adults (66.0±3.5 years) performed a motor imagery task of gait as well as a matched visual imagery task. Task difficulty was modulated to investigate differential activation for precise control of gait. Task performance was assessed by recording motor imagery latencies, eye movements, and electromyography during functional magnetic resonance imaging scanning. RESULTS Our results showed that both healthy older and young adults recruited a network of brain regions comprising the bilateral supplementary motor cortex and primary motor cortex, right prefrontal cortex, and cerebellum, during motor imagery of gait. We observed an age-related increase in brain activity in the right supplementary motor area (BA6), the right orbitofrontal cortex (BA11), and the left dorsolateral frontal cortex (BA10). Activity in the left hippocampus was significantly modulated by task difficulty in the elderly participants. Executive functioning correlated with magnitude of increases in right primary motor cortex (BA4) during the motor imagery task. CONCLUSIONS Besides demonstrating a general overlap in brain regions recruited in young and older participants, this study shows age-related changes in cerebral activation during mental imagery of gait. Our results underscore the importance of executive function (dorsolateral frontal cortex) and spatial navigation or memory function (hippocampus) in gait control in elderly individuals.