Does Parkinson's disease affect judgement about another person's action?

The observer's motor system has been shown to be involved in observing the actions of another person. Recent findings suggest that people with Parkinson's disease do not show the same motor facilitatory effects when observing the actions of another person. We studied whether Parkinson's patients were able to make unspeeded judgements about another person's action. Participants were asked to watch video clips of an actor lifting a box containing different weights (100, 200, 300 or 400 g) and to guess the weight that was being lifted on a 9-point scale. We compared the performance of 16 patients with PD with 16 healthy age-matched controls. Both groups were able to do the task, showing a significant relationship between the real weight and the guessed weight, albeit with a tendency to overestimate the lowest weight and underestimate the heaviest weight. The PD patients, however, showed a reduced slope value. These results show that despite their own motor deficits, PD patients are still able to judge the weight being lifted by another person, albeit with a slight reduction in accuracy. Further research will be required to determine whether PD patients use a motor simulation or a visual compensatory strategy to achieve this.

Feasibility and Acceptability of Computerised Cognitive Training of Everyday Cognition in Parkinson's Disease.

OBJECTIVES: We piloted a computerised cognitive training battery in a group of participants with Parkinson's disease without dementia to investigate the relevance of the training to daily life and the feasibility and the acceptability of the tasks. Previous studies of CT have had limited success in the benefits of training, extending to improvements in everyday function. By taking a pragmatic approach and targeting training to the cognitive skills affected by Parkinson's disease (planning, attention, and recollection), whilst using tasks that emulated real-life scenarios, we sought to understand whether participants perceived the training to be effective and to identify the elements of the training that elicited beneficial effects. METHODS: Four participants completed a cognitive training session comprising three distinct tasks 5 days a week over two weeks. Participants completed baseline questionnaires examining health-related quality of life, everyday cognition, and apathy before the training period, after the last session, and two weeks after the last session. An interview was held after participants had completed the training. RESULTS: The findings indicated that participants felt the training was acceptable, enhanced their awareness, and encouraged them to monitor their thinking abilities. The group interview indicated that the training was feasible; participants felt the tasks had potential to improve everyday performance, but more supporting information should be provided to facilitate this transfer. Responses to the questionnaires reflected these findings, indicating improvement for some participants' cognition and quality of life. Objective measures supported the subjective reports; there were improvements in some but not all domains. Performance on the planning and recollection tasks improved over the training period, and the evidence for improvement on the attention task was mixed. CONCLUSION: This study has found that pragmatic computer-based training with real-life outcomes is both feasible and acceptable and should be evaluated more extensively using controlled methods.

The physiology of orthostatic tremor.

This article describes the physiological findings in a patient with orthostatic tremor. The tremor primarily affected the legs, was alternating between antagonist muscle groups, and had a remarkably rapid frequency of 16 Hz. It was present only during certain postures and appeared to be of central origin. A tremor of the same frequency was also recorded in the arms during particular movements, but was cocontracting. We suggest that orthostatic tremor may be generated by spontaneous oscillation in those central structures responsible for organizing the motor programs for standing.

Heightened intrathecal release of proinflammatory cytokines in Creutzfeldt-Jakob disease.

The authors report high intrathecal release of tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-1beta in five patients with sporadic or new-variant Creutzfeldt-Jakob disease (CJD) without activation of the humoral or lymphocytic immune responses. Increased release of TNF-alpha and IL-1beta was also detected in some patients with progressive dementias. CJD is associated with a local cerebral host response that involves the release of proinflammatory cytokines.

Cannabinoids reduce levodopa-induced dyskinesia in Parkinson's disease: a pilot study.

The lateral segment of the globus pallidus (GPl) is thought to be overactive in levodopa-induced dyskinesia in PD. Stimulation of cannabinoid receptors in the GPl reduces gamma-aminobutyric acid (GABA) reuptake and enhances GABA transmission and may thus alleviate dyskinesia. In a randomized, double-blind, placebo-controlled, crossover trial (n = 7), the authors demonstrate that the cannabinoid receptor agonist nabilone significantly reduces levodopa-induced dyskinesia in PD.

Increase of the Bereitschaftspotential in simultaneous and sequential movements.

The amplitude and duration of the Bereitschaftspotential were analysed in 9 normal subjects prior to four different motor tasks: (1) simple isotonic elbow flexion ('flex'), (2) simple isometric finger flexion ('squeeze'), (3) simultaneous performance of 'flex' and 'squeeze', and (4) sequential performance of 'flex' then 'squeeze'. The Bereitschaftspotential was much larger and slightly longer in the simultaneous and sequential movements than in the same movements performed separately. The amplitudes of the Bereitschaftspotential were measured 150 and 75 ms prior to electromyographic (EMG) onset of the prime mover, and at the time of EMG onset. Changes in size were seen in all leads (FCz, Cz, C3', C4') and at all time points. It is suggested that the increase of the Bereitschaftspotential prior to complex arm movements reflects a greater activation of the supplementary motor area before simultaneous and sequential movements.

Different sites of action of electrical and magnetic stimulation of the human brain.

The latency of the surface recorded electromyographic response to either an electrical or magnetic stimulus applied to the scalp has been measured in the first dorsal interosseous and abductor pollicis brevis muscles of 3 subjects. In the contracting muscle the response latency to the magnetic stimulus was longer by 1.4-2.7 ms compared to the electrical stimulus. Poststimulus time histograms of the firing of single motor units of first dorsal interosseous muscle were studied in 4 subjects. The first period of increased probability of firing of the single motor units showed a similar latency difference (mean 2.8 ms) to the two modes of stimulation. It is concluded that the extra delay to magnetic stimulation is consumed in central motor pathways. This implies that the two modes of stimulation activate the brain at different sites. It is suggested that the magnetic stimulus excites the corticospinal neurones transynaptically, whereas the electrical stimulus excites these neurones directly.

Modulation of the long-latency reflex to stretch by the supplementary motor area in humans.

Surface-recorded, electromyographic responses to 200-ms ramp stretches were studied in the wrist flexor muscles from both arms of a patient with clinical and radiographic evidence of infarction in the right supplementary motor area (SMA). They were compared with those from 8 age-matched control subjects. The latencies of the spinal component of the stretch reflex were slightly longer than normal in both arms of the patient (normal subjects: 28.5 +/- 2.6 ms; patient: 35 ms, right arm and 32 ms left arm). However, the amplitude and duration of the short-latency response were identical in both arms. The onset of the long-latency response to stretch was symmetrical in both the patient's arms and was slightly later than normal (normal subjects 55.5 +/- 4.0 ms, patient: 72 ms right arm and 70 ms left arm); however, its duration was considerably prolonged in the arm contralateral to the SMA lesion (normal subjects: 44.8 +/- 6.0 ms; patient: 48 ms right arm. 105 ms left arm). These results are consistent with the hypothesis that the long-latency stretch reflex is mediated via a transcortical loop.

The interpretation of electromyographic responses to electrical stimulation of the motor cortex in diseases of the upper motor neurone.

The complexities of interpreting results of electrical stimulation of the motor cortex in pathological states are discussed and illustrated by reference to results from a variety of patients with diseases affecting the upper motor neurone (multiple sclerosis, cervical spondylosis and myelopathy, motor neurone disease, hemiparesis due to cerebral infarction, and hereditary spastic paraplegia). The abnormalities of the electromyographic (EMG) responses after anodal cortical stimulation consisted of delay in the latency to onset, dispersion or reduction in response size or even absence of EMG responses. These changes were not confined to any specific condition or pathology. Previous work has suggested that the sequence of events that follow anodal cortical stimulation involves repetitive excitatory inputs to spinal motoneurones and transmission across at least one central synapse. Accordingly, delayed latencies may not exclusively indicate slowing of motor conduction, while the absence of any response may not indicate complete failure of conduction in corticomotoneurone pathways.

Some experiences of techniques for stimulation of the human cerebral motor cortex through the scalp.

Stimulation of the motor cortex transcranially has shown a rough somatotopy of stimulation sites on the scalp corresponding to the homunculus and preferential activation of contralateral hand muscles, as well as very short latencies of signals in the cervical spinal cord. The responses are also facilitated by background activation of the muscles. We are reporting a set of patients studied using electrical and magnetic stimulation transcranially. We observed that the latency of electromyogram activation is much shorter in active than contracting muscles and that the muscle twitch produced by cortical stimulation can exceed the force produced by supramaximal stimulation of the peripheral nerve. Our findings suggest that this may be due to multiple firing of motor neurons. Another observation is that magnetic stimulation is not as subject to a reduction in the response latency with facilitation, and response latencies with magnetic stimulation were 2 ms longer than with electrical stimulation. The implications of these findings are discussed.

Listeriosis and recurrent abortion in a renal transplant recipient.

A 29-year-old farmer's wife had received a kidney from her brother (of identical HLA type) at the age of 22 years. She was afterwards immunosuppressed with prednisolone and azathioprine. Her first pregnancy had been uneventful but the second and third had terminated spontaneously at 15 and 24 weeks gestation respectively. Following the third pregnancy, Listeria monocytogenes (serotype 4) was grown from the fetus, the placenta and maternal blood. Over the next 18 months, antibody titres which were assessed by an IgG indirect immunofluorescent antibody assay remained high. When the patient became pregnant for a fourth time, 9 months after her second abortion, 250 mg ampicillin were administered three times daily for the remaining duration of the pregnancy. A second child was successfully delivered by Caesarean section at 39 weeks' gestation.

A SPECT study of the effect of vagal nerve stimulation on thalamic activity in patients with epilepsy.

The mechanism by which vagal nerve stimulation (VNS) exerts an anticonvulsant effect in humans is unknown. This study used (99m)Tc-HMPAO single photon emission tomography (SPECT) to examine the effects of VNS on regional cerebral activity in thalamic and insular regions. Seven subjects with epilepsy who had been receiving vagal nerve stimulation for at least 6 months underwent SPECT scanning with simultaneous scalp electroencephalographic (EEG) recording. Subjects were studied in two states; during VNS activity and during a comparison condition of VNS inactivity. A region of interest analysis demonstrated that rapid cycling stimulation (7 seconds on, 12 seconds off) was associated with relatively decreased activity in left and right medial thalamic regions. No systematic stimulation-related changes were observed on visual or spectral analysis of EEG data. The thalamus is involved in modulation of ongoing cortical EEG activity in animals. Our results support the hypothesis that VNS may exert an antiepileptic action by an effect on thalamic activity.

The deep tendon and the abdominal reflexes.

The deep tendon reflexes (and the abdominal reflexes) are important physical signs which have a special place in neurological diagnosis, particularly in early disease when they alone may be abnormal. They act as "hard" signs in situations where clinical assessment is complicated by patient anxiety, and become more useful as clinical experience develops.

Patients with Parkinson's disease can employ a predictive motor strategy.

We have tested the hypothesis that predictive motor behaviour is abnormal in Parkinson's disease. In the first experiment elbow movements were performed to track a moving spot on an oscilloscope screen. The performance of 12 patients with Parkinson's disease and eight age-matched control subjects was measured when tracking a repeated pattern under two conditions. In the first condition subjects were not aware of the repetitive nature of the tracking task whilst in the second condition they were. For both groups tracking error and tracking lag were less when aware of the repetition. In the second experiment wrist movements were studied. Five age-matched controls were compared with five patients, studied on and off drugs. In this experiment the performance tracking a repeated pattern was compared to that tracking unpredictable patterns. Tracking lags were reduced to very low values (less than 20 ms) in response to the repeated pattern for both groups. This was true even when the patients were relatively immobile off drugs. We conclude that patients with Parkinson's disease are capable of predictive motor behaviour although such a strategy does not always confer as great an advantage in reducing tracking error in patients compared with control subjects.

Left atrial ball valve thrombus. Treatable cause of clinical deterioration in a patient with mitral stenosis.

A 74 year old woman with mixed mitral valve disease presented with episodes of loss of consciousness and fainting. The attacks were noted to be closely related to posture, especially crouching, and this, with the clinical finding that the radial pulse disappeared before she lost consciousness, suggested the diagnosis of a ball valve thrombus. Cardiac catheterisation confirmed the diagnosis but was followed by a fall in blood pressure necessitating emergency surgery. The only position in which the circulation could be maintained was the right lateral, with steep head down tilt, and left femoro-femoral cardiopulmonary bypass had to be established in this position. Operation confirmed the presence of a ball valve thrombus and the patient recovered uneventfully.

Central motor conduction studies in hereditary spastic paraplegia.

Central motor conduction (CMC) studies were carried out in 25 patients with hereditary spastic paraplegia (HSP). Responses evoked in the lower limbs by transcranial magnetic stimulation of the motor cortex were bilaterally absent in 33% of the patients and, when recordable, were delayed in 75% of cases. Responses in the upper limbs were mostly normal except for those from the five members of one family, which were considerably delayed. There was no correlation between CMC parameters and age, duration of disease or upper limb hyperreflexia. CMC time to the tibialis anterior correlated with disability in patients with juvenile-onset HSP. It is concluded that CMC studies are not useful in detecting subclinical lesions in hereditary spastic paraplegia but may be of value in identifying subgroups of the disease.