Distinct Olfactory Cross-Modal Effects on the Human Motor System

BACKGROUND: Converging evidence indicates that action observation and action-related sounds activate cross-modally the human motor system. Since olfaction, the most ancestral sense, may have behavioural consequences on human activities, we causally investigated by transcranial magnetic stimulation (TMS) whether food odour could additionally facilitate the human motor system during the observation of grasping objects with alimentary valence, and the degree of specificity of these effects. METHODOLOGY/PRINCIPAL FINDINGS: In a repeated-measure block design, carried out on 24 healthy individuals participating to three different experiments, we show that sniffing alimentary odorants immediately increases the motor potentials evoked in hand muscles by TMS of the motor cortex. This effect was odorant-specific and was absent when subjects were presented with odorants including a potentially noxious trigeminal component. The smell-induced corticospinal facilitation of hand muscles during observation of grasping was an additive effect which superimposed to that induced by the mere observation of grasping actions for food or non-food objects. The odour-induced motor facilitation took place only in case of congruence between the sniffed odour and the observed grasped food, and specifically involved the muscle acting as prime mover for hand/fingers shaping in the observed action. CONCLUSIONS/SIGNIFICANCE: Complex olfactory cross-modal effects on the human corticospinal system are physiologically demonstrable. They are odorant-specific and, depending on the experimental context, muscle- and action-specific as well. This finding implies potential new diagnostic and rehabilitative applications

The influence of diabetes and hyperglycemia on clinical course after intracerebral hemorrhage.

OBJECTIVE: To determine whether diabetes and admission hyperglycemia in nondiabetic patients influence outcome and the occurrence of cerebral and medical complications after intracerebral hemorrhage (ICH). METHODS: The study sample included 764 patients with ICH. The effects of diabetes and admission hyperglycemia were examined in relation to 30-day and 3-month mortality using Cox regression models controlling for potential confounders. The analysis was conducted for the entire sample of patients and repeated in comatose and noncomatose patients. RESULTS: Among comatose patients, neither diabetes nor admission hyperglycemia contributed significant predictive information, as nearly all patients died. In noncomatose patients, diabetes was an independent predictor of 30-day (odds ratio [OR] 1.31; 95% CI 1.08 to 1.58) and 3-month (OR 1.30; 95% CI 1.08 to 1.56) mortality and was associated with a greater incidence of infectious (OR 1.24; 95% CI 1.03 to 1.49) and cerebral (OR 1.42; 95% CI 1.10 to 1.83) complications. Among nondiabetic patients with Glasgow Coma Scale score of >8, hyperglycemia was an independent predictor of 30-day (OR 1.29; 95% CI 1.05 to 1.58) and 3-month (OR 1.27; 95% CI 1.05 to 1.53) mortality and was associated with a greater incidence of cerebral complications (OR 1.47; 95% CI 1.12 to 2.94). CONCLUSIONS: Both diabetes and admission hyperglycemia in nondiabetic patients are predictors of poor outcome after supratentorial ICH. This may be related to the greater incidence of cerebral and infectious complications in diabetic patients and of cerebral complications in hyperglycemic nondiabetic patients

PRIMARY INTRAVENTRICULAR HAEMORRHAGE IN ADULTS

INTRODUCTION: Primary intraventricular haemorrhage (PIVH) is an uncommon type of intracerebral haemorrhage. Relatively little is known about clinical and imaging features, and even less about prognosis and predictors of mortality. MATERIAL AND METHODS: We analysed clinical and imaging features, causative factors and outcome of 26 patients with CT brain scan evidence of PIVH. A multivariate regression model of failure time data was used to assess predictors of in-hospital mortality. RESULTS: Loss of consciousness was the first manifestation of PIVH in six patients and occurred after all other symptoms in five. In other patients, onset was characterized by headache, vomiting, confusion and disorientation (n=8) or by headache with or without vomiting (n=7). Angiography revealed vascular malformations in eight patients (31%). Other possible causative factors were clotting disorder in one patient and arterial hypertension in 10. No cause was identified in seven patients. Early hydrocephalus was the most frequent complication and resolved spontaneously in a minority of patients. In-hospital mortality was high (42%): four patients died early of direct consequence of bleeding and seven died after clinical worsening because of increasing hydrocephalus or other adverse events. Multivariate analysis indicated Glasgow Coma Scale < or = 8 (OR 4.67; 95% CI 1.22-17.92) and early hydrocephalus (OR 4.93; 95% CI 1.13-21.59) as independent predictors of in-hospital mortality. CONCLUSION: In patients with PIVH, hydrocephalus seems to be a critical determinant of in-hospital mortality and this suggests the need for early treatment strategies

Time course of frontal somatosensory evoked potentials. Relation to L-dopa plasma levels and motor performance in PD

OBJECTIVE: To verify whether the change in L-dopa plasma levels after a single dose of carbidopa/L-dopa 50/200 (controlled-release) transiently modifies frontal components of somatosensory evoked potentials (SEPs) in patients with PD in parallel with improvement of motor performance. BACKGROUND: Apomorphine, a potent dopamine-agonist drug, transiently increases frontal SEP components, which may be depressed in PD; however, relationships between clinical status, frontal SEPs, and therapy are still unclear. METHODS: Nineteen PD patients (mean age 65.9 years, range 52 to 77, responders to L-dopa therapy, were studied in the same day at times T0 (baseline predose level), T1 (presumed L-dopa peak time), and T2 (end of dose-induced motor response). The following were monitored: L-dopa plasma concentration, tapping test, reaction times, peak latency (with central conduction times), and amplitude of cervical, subcortical, as well as cortical parietal and frontal SEP components elicited by median nerve stimulation of the more clinically affected arm. RESULTS: The average amplitude of frontal components of PD patients was significantly reduced at T0 with respect to control subjects. A significant and transient amplitude increase of frontal SEPs was found at T1, in parallel with the L-dopa peak concentration and improvement in motor performance (tapping and reaction times), without significant changes in amplitude of parietal SEP waves. No latency shifts were observed in brain and spinal waves. CONCLUSIONS: L-Dopa may influence the responsiveness of the parkinsonian brain as assessed by frontal somatosensory evoked potentials. The time course of these modifications coincides with that of the clinical response in the motor performance

Reduction of cortical myoclonus-related epileptic activity following slow-frequency rTMS.

In a drug-resistant epilepsy patient with continuous forearm/hand positive myoclonia due to a focal cortical dysplasia of the right motor cortex, cortical jerk-related and electromyographic activity were recorded for 15 min before and after 1 Hz rTMS (15 min, 10% below the resting excitability threshold) of the right motor cortex. A stable negative cortical spike, time-locked with contralateral muscle jerks (60 > 100 microV), was detected only at perirolandic electrodes (maximal amplitudes: block 1 = 21.3 microV, block 2 = 22 microV, block 3 = 25.9 microV). After rTMS, only 20 muscle jerks accomplished the criterion of > 100 microV; blind back-averaging of these disclosed a topographically similar cortical spike, but with amplitude reduced by at least 50% (11.2 microV). This represents in vivo evidence of the possibility to selectively modulate the activity of an epileptic focus by intervening with local low-frequency rTMS

An electromyographic evaluation of motor complications in thoracic herpes zoster

Motor complications in thoracic herpes zoster were evaluated in 52 patients by electromyographic examination of the paraspinal muscles. At the initial EMG examination, abnormal findings were observed in 18 patients (35%). In 8 patients the myomers involved coincided in location with affected dermatomes, while in 10 patients, in addition to the involvement of myomers corresponding to affected dermatomes, there also appeared an involvement of one or more contiguous myomers not corresponding to affected dermatomes. Our study demonstrated that motor involvement in thoracic HZ is much more common than previously suggested and its incidence (35%) appears to be greater than that reported in both cervical and lumbosacral HZ