Nicola Smania

Motor disinhibition in affected and unaffected hemisphere in the early period of recovery after stroke.

OBJECTIVES To investigate motor disinhibition in affected and unaffected motor areas in the acute stage after stroke and during the early period of recovery. METHODS Fifteen patients with moderate to severe hemiparesis after acute unilateral stroke were compared with 10 healthy age-matched controls. We used paired transcranial magnetic stimulation to study intracortical inhibition and facilitation from the thenar eminence muscles on both sides. F-wave from the median nerve on both sides were recorded. The recordings were performed 5-7 days (T1) and 30 days after stroke. RESULTS In 10 patients who showed the presence of reliable motor evoked potentials on the affected side, intracortical inhibition was significantly reduced. On the unaffected side intracortical inhibition (ICI) was significantly reduced in all patients. Patients who presented significant motor recovery after 30 days showed persistence of abnormal disinhibition in the affected hemisphere but a return to normal ICI in the unaffected hemisphere. Patients with poor motor recovery showed persistence of abnormal disinhibition on both sides. No significant changes were observed in F-wave amplitude. CONCLUSIONS Motor disinhibition occurs on both sides after stroke in all acute stage patients. Changes in motor disinhibition on unaffected side also are related to motor recovery.

Pain and motor complications in Parkinson's disease

Aims: To study the association of pain with motor complications in 117 patients with Parkinson’s disease. Methods: Patients were asked to refer any pain they experienced at the time of study and lasting since at least 2 months. Basic parkinsonian signs and motor complications (including motor fluctuations and dyskinesia) were assessed and Unified Parkinson’s Disease Rating Scale (UPDRS) motor score part III (during on) and part IV were calculated. Information on age, sex, duration of disease, use of dopamine agonists and levodopa, years of levodopa treatment and current levodopa dosage, medical conditions possibly associated with pain, and depression were collected. Single and multiple explanatory variable logistic regression models were used to check the association of pain with the investigated variables. Results: Pain was described by 47 patients (40%) and could be classified into dystonic (n.19) and non dystonic pain (n.16); in 12 patients both types coexisted. Multiple explanatory variable logistic regression models indicated a significant association of pain with motor complications (adjusted OR, 5.7; 95% CI, 2 to 16.5; p = 0.001). No association was found between pain, dystonic or non dystonic, and the other investigated variables including medical conditions known to be associated to pain in the general population. There was a significant correlation (r = 0.31, p<0.05) between severity of pain (measured on a Visual Analogue Scale) and severity of motor complications (UPDRS part IV). Conclusions: Pain may be a representative feature of Parkinson’s disease frequently associated with motor complications. The association is independent of a number of potentially relevant demographic and clinical variables.

Neural Underpinnings of Gesture Discrimination in Patients with Limb Apraxia

Limb apraxia (LA), is a neuropsychological syndrome characterized by difficulty in performing gestures and may therefore be an ideal model for investigating whether action execution deficits are causatively linked to deficits in action understanding. We tested 33 left brain-damaged patients and 8 right brain-damaged patients for the presence of the LA. Importantly, we also tested all the patients in an ad hoc developed gesture recognition task wherein an actor performs, either correctly or incorrectly, transitive (using objects) or intransitive (without objects) meaningful conventional limb gestures. Patients were instructed to judge whether the observed gesture was correct or incorrect. Lesion analysis enabled us to evaluate the relationship between specific brain regions and behavioral performance in gesture execution and gesture comprehension. We found that LA was present in 21 left brain-damaged patients and it was linked to frontal and parietal lesions. Moreover, we found that recognition of correct execution of familiar gestures performed by others was more impaired in patients with LA than in nonapraxic patients. Crucially, the gesture comprehension deficit correlated with damage to the opercular and triangularis portions of the inferior frontal gyrus, two regions that are involved in complex aspects of action-related processing. In contrast, no such relationship was observed with lesions centered on the inferior parietal cortex. The present findings suggest that lesions to left frontal regions that are involved in planning and performing actions are causatively associated with deficits in the recognition of the correct execution of meaningful gestures.

Effect of Balance Training on Postural Instability in Patients With Idiopathic Parkinson’s Disease

Background. Postural instability (PI) is a disabling sign of Parkinson’s disease (PD) not easily amenable to treatment with medication. Objective. To evaluate the effects of balance training on PI in patients with PD. Methods. A total of 64 patients with PI were randomly assigned to the experimental group (n = 33) for balance training or to the control group (n = 31) for general physical exercises. Each patient received 21 treatment sessions of 50 minutes each. Patients were evaluated by a blinded rater before and after treatment as well as 1 month posttreatment using the Berg Balance Scale (BBS), Activities-Specific Balance Confidence Scale (ABC), postural transfer test, self-destabilization of the center of foot pressure test, number of falls, Unified Parkinson’s Disease Rating Scale (UPDRS), modified Hoehn and Yahr (H&Y) Staging Scale, and Geriatric Depression Scale (GDS). Results .At the end of treatment, the experimental group showed significant improvements in all outcome measures, except for the UPDRS and the H&Y scale. Improvement was maintained at the 1-month follow-up in all outcome measures except for the GDS. No significant changes in performance were observed in the control group. Conclusions. A program of balance training can improve PI in patients with PD.

Frames of Reference for Mapping Tactil Stimuli in Brain-Damaged Patients

Twelve normal controls, twelve left-brain-damaged patients, and thirty-six right-brain-damaged patients with or without tactile extinction or tactile neglect were asked to report light touches delivered to the left or the right hand or simultaneously to both hands. The hands could be in anatomic position or one hand could cross over the other. Moreover, the two hands could be in the left or the right hemispace or across the corporeal midline. Controls and nontactile-extinction groups performed better when the hands were in anatomical than in crossed position. By contrast, patients with tactile extinction detected contralesional stimuli with higher accuracy in crossed than in anatomical position. This result suggests that, in these patients, impairments in detecting contralesional stimuli can be due not only to sensory but also to spatial factors contingent upon the position of the hands. There was no interaction between the effect of crossing the hands and the hemispace where the crossing took place. This suggests that coding the position of a hand as left or right does not necessarily occur in relation to the bodily midline, but it may arise from the computation of the position of the other hand.

Motor Cortical Disinhibition During Early and Late Recovery After Stroke

Background. Functional neuroimaging studies show adaptive changes in areas adjacent and distant from the stroke. This longitudinal study assessed whether changes in cortical excitability in affected and unaffected motor areas after acute stroke correlates with functional and motor recovery. Methods. We studied 13 patients with moderate to severe hemiparesis 5 to 7 days (T1), 30 days (T2), and 90 days (T3) after acute unilateral stroke, as well as 10 healthy controls. We used paired-pulse transcranial magnetic stimulation to study intracortical inhibition and facilitation, recording from the bilateral thenar eminences. F waves were also recorded. Results. At T1, all patients showed significantly reduced intracortical inhibition in the unaffected hemisphere. At T2, in patients whose motor function recovered, intracortical inhibition in the unaffected hemisphere returned to normal. In patients with poor clinical motor recovery, abnormal disinhibition persisted in both hemispheres. At T3, in patients whose motor function progressively recovered, the abnormal disinhibition in the unaffected hemisphere decreased further, whereas in patients whose motor function remained poor, abnormal inhibition in the unaffected hemisphere persisted. No modification of F-wave latency and amplitude were found in patients and controls. Conclusions. During early days after stroke, motor cortical disinhibition involves both cerebral hemispheres. Longitudinal changes in motor disinhibition of the unaffected hemisphere may reflect the degree of clinical motor recovery.

Disownership of left hand and objects related to it in a patient with right brain damage

WE describe a woman with right brain damage who denied the ownership of her left hand and of extracorporeal objects (e.g. rings) which were worn on the left hand itself. When the same objects were worn on the right hand or were held by the examiner, the patient correctly recognized them as her own. Other personal objects unrelated to the left hand (e.g. pins, earrings, comb) were always correctly recognized as her own. Thus, by inference, the mental image of ones body may include inanimate objects which had been in contact or in close proximity with the body itself. These findings provide, for the first time, experimental support to the speculative notion of an extended body schema.

Active Finger Extension A Simple Movement Predicting Recovery of Arm Function in Patients With Acute Stroke

Background and Purpose— Early prognosis of arm recovery is a major clinical issue in stroke. The aim of this study was to assess the prognostic value of 4 simple bedside tests. Methods— Forty-eight patients with arm paresis/plegia were evaluated on days 7, 14, 30, 90 and 180 after stroke. Assessment included 4 potential predictors of arm recovery (active finger extension, shoulder abduction, shoulder shrug and hand movement scales) and 3 outcome measures evaluating arm function (Nine Hole Peg Test, Fugl-Meyer arm subtest, Motricity Index arm subtest). Results— The active finger extension scale was the most powerful prognostic factor. Patients with active finger extension scores >3 had a high probability of achieving good performance as assessed by the Motricity Index. Conclusions— Active finger extension is a reliable early predictor of recovery of arm function in stroke patients.

Implicit redundant-targets effect in visual extinction.

Patients with left visual extinction as a result of unilateral right hemisphere damage were tested on a redundant-targets effect paradigm (RTE). LED-generated brief flashes were lateralized either to the left or to the right visual hemifield or presented bilaterally. Subjects were asked to press a key as fast as possible following either unilateral or bilateral stimuli and immediately afterwards to report on the number of stimuli presented. As previously found in normal subjects, bilateral stimuli were responded to faster than unilateral ones, and this was evidence of a RTE. The main thrust of this study was that extinction patients showed a RTE not only for correctly perceived bilateral stimuli but also in trials in which they extinguished the stimulus on the field contralateral to the lesion. This result is compatible with a preserved processing of the extinguished input at least up to the stage at which it may interact with the input from the normal side to yield a speeded motor response. Interestingly, the implicit redundancy gain of extinction patients was found to fit a coactivation (i.e. neural) rather than a probabilistic model.

Abnormal processing of the nociceptive input in Parkinson's disease : A study with CO2 laser evoked potentials

&NA; Since a number of patients with Parkinson’s Disease (PD) complain of painful sensations, we studied whether the central processing of nociceptive inputs is abnormal in PD. To test this hypothesis, we recorded scalp CO2 laser evoked potentials (LEPs) to hand skin stimulation in 18 pain‐free PD patients with unilateral bradykinetic‐rigid syndrome (hemiparkinson) during the off state and in 18 healthy subjects. This technique allows us to explore non‐invasively the functional status of some cerebral structures involved in nociceptive input processing. In both PD patients and control subjects, CO2 laser stimulation gave rise to a main negative N2 potential followed by a positive P2 response at vertex peaking at a latency of about 200 and 300 ms, respectively. These potentials are thought to originate from several brain structures devoted to nociceptive input processing, including the cingulate gyrus and insula. PD patients and normal subjects showed comparable N2 and P2 latencies, whereas the N2/P2 peak‐to‐peak amplitude was significantly lower in PD patients (regardless of the clinically affected body side) than in controls. LEPs were even recorded after acute L‐dopa administration in 7 additional PD patients. L‐dopa administration yielded no significant change in N2/P2 amplitude as compared to the off state. These results suggest an abnormal nociceptive input processing in pain‐free PD patients which appears to be independent of clinical expression of parkinsonian motor signs and is not affected by dopaminergic stimulation.