Cerebellar Purkinje cell simple spike discharge encodes movement velocity in primates during visuomotor arm tracking.
Pathophysiological, lesion, and electrophysiological studies suggest that the cerebellar cortex is important for controlling the direction and speed of movement. The relationship of cerebellar Purkinje cell discharge to the control of arm movement parameters, however, remains unclear. The goal of this study was to examine how movement direction and speed and their interaction-velocity-modulate Purkinje cell simple spike discharge in an arm movement task in which direction and speed were independently controlled. The simple spike discharge of 154 Purkinje cells was recorded in two monkeys during the performance of two visuomotor tasks that required the animals to track targets that moved in one of eight directions and at one of four speeds. Single-parameter regression analyses revealed that a large proportion of cells had discharge modulation related to movement direction and speed. Most cells with significant directional tuning, however, were modulated at one speed, and most cells with speed-related discharge were modulated along one direction; this suggested that the patterns of simple spike discharge were not adequately described by single-parameter models. Therefore, a regression surface was fitted to the data, which showed that the discharge could be tuned to specific direction-speed combinations (preferred velocities). The overall variability in simple spike discharge was well described by the surface model, and the velocities corresponding to maximal and minimal discharge rates were distributed uniformly throughout the workspace. Simple spike discharge therefore appears to integrate information about both the direction and speed of arm movements, thereby encoding movement velocity. (+info)
The endovascular management of blue finger syndrome.
OBJECTIVES: To review our experience of the endovascular management of upper limb embolisation secondary to an ipsilateral proximal arterial lesion. DESIGN: A retrospective study. MATERIALS AND METHODS: Over 3 years, 17 patients presented with blue fingers secondary to an ipsilateral proximal vascular lesion. These have been managed using transluminal angioplasty (14) and arterial stenting (five), combined with embolectomy (two) and anticoagulation (three)/anti-platelet therapy (14). RESULTS: All the patients were treated successfully. There have been no further symptomatic embolic episodes originating from any of the treated lesions, and no surgical amputations. Complications were associated with the use of brachial arteriotomy for vascular access. CONCLUSIONS: Endovascular techniques are safe and effective in the management of upper limb embolic phenomena associated with an ipsilateral proximal focal vascular lesion. (+info)
Randomized, controlled trial to evaluate increased intensity of physiotherapy treatment of arm function after stroke.
BACKGROUND AND PURPOSE: Many patients have impaired arm function after stroke, for which they receive physiotherapy. The aim of the study was to determine whether increasing the amount of physiotherapy early after stroke improved the recovery of arm function and to compare the effects of this therapy when administered by a qualified therapist or a trained, supervised assistant. The physiotherapy followed a typical British approach, which is Bobath derived. Ten hours of additional therapy were given over a 5-week period. METHODS: The study design was a single-blind, randomized, controlled trial. Stroke patients were recruited from those admitted to the hospital in the 5 weeks after stroke. They were randomly allocated to routine physiotherapy, additional treatment by a qualified physiotherapist, or additional treatment by a physiotherapy assistant. Outcome was assessed after 5 weeks of treatment and at 3 and 6 months after stroke on measures of arm function and of independence in activities of daily living. RESULTS: There were 282 patients recruited to the study. The median initial Barthel score was 6.5, and the median age of the patients was 73 years. The median initial Rivermead Motor Assessment Arm score was 1. There were no significant differences between the groups at randomization or on any of the outcome measures. Only half of the patients allocated to the 2 additional-therapy groups completed the program. CONCLUSIONS: This increase in the amount of physiotherapy for arm impairment with a typical British approach given early after stroke did not significantly improve the recovery of arm function in the patients studied. A number of other studies of interventions aimed at rehabilitation of arm function have reported positive results. Such findings may have been due to the content of these interventions, to the greater intensity of the interventions, or to the selection of patients to whom the treatments were applied. (+info)
Superficial femoral eversion endarterectomy combined with a vein segment as a composite artery-vein bypass graft for infrainguinal arterial reconstruction.
OBJECTIVE: The purpose of this study was to determine the results of composite artery-vein bypass grafting for infrainguinal arterial reconstruction. METHODS: This study was designed as a retrospective case series in two tertiary referral centers. Forty-eight of 51 patients underwent the procedure of interest for the treatment of ischemic skin lesions (n = 42), rest pain (n = 3), disabling claudication (n = 1), and infected prosthesis (n = 2). The intervention used was infrainguinal composite artery-vein bypass grafting to popliteal (n = 18) and infrapopliteal (n = 30) arteries, with an occluded segment of the superficial femoral artery prepared with eversion endarterectomy and an autogenous vein conduit harvested from greater saphenous veins (n = 43), arm veins (n = 3), and lesser saphenous veins (n = 2). The main outcome measures, primary graft patency rates, foot salvage rates, and patient survival rates, were described by means of the life-table method for a mean follow-up time of 15.5 months. RESULTS: The cumulative loss during the follow-up period was 6% and 24% at 6 and 12 months, respectively. The primary graft patency rates, the foot salvage rates, and the patient survival rates for patients with popliteal grafts were 60.0% +/- 9.07%, 75.7% +/- 9.18%, and 93.5% +/- 6.03%, respectively, at 1 month; 53.7% +/- 11.85%, 68.9% +/- 12.47%, and 85. 0% +/- 9.92% at 1 year; and 46.7% +/- 18.19%, 68.9% +/- 20.54%, and 53.1% +/- 17.15% at 5 years. For infrapopliteal grafts, the corresponding estimates were 72.4% +/- 7.06%, 72.9% +/- 6.99%, and 92.7% +/- 4.79% at 1 month; 55.6% +/- 10.70%, 55.4% +/- 10.07%, and 77.9% +/- 9.02% at 1 year; and 33.6% +/- 22.36%, 55.4% +/- 30.20%, and 20.8% +/- 9.89% at 5 years. CONCLUSION: The composite artery-vein bypass graft is a useful autogenous alternative for infrainguinal arterial reconstruction when a vein of the required quality is not available or when the procedure needs to be confined to the affected limb. (+info)
Right atrial bypass grafting for central venous obstruction associated with dialysis access: another treatment option.
PURPOSE: Central venous obstruction is a common problem in patients with chronic renal failure who undergo maintenance hemodialysis. We studied the use of right atrial bypass grafting in nine cases of central venous obstruction associated with upper extremity venous hypertension. To better understand the options for managing this condition, we discuss the roles of surgery and percutaneous transluminal angioplasty with stent placement. METHODS: All patients had previously undergone placement of bilateral temporary subclavian vein dialysis catheters. Severe arm swelling, graft thrombosis, or graft malfunction developed because of central venous stenosis or obstruction in the absence of alternative access sites. A large-diameter (10 to 16 mm) externally reinforced polytetrafluoroethylene (GoreTex) graft was used to bypass the obstructed vein and was anastomosed to the right atrial appendage. This technique was used to bypass six lesions in the subclavian vein, two lesions at the innominate vein/superior vena caval junction, and one lesion in the distal axillary vein. RESULTS: All patients except one had significant resolution of symptoms without operative mortality. Bypass grafts remained patent, allowing the arteriovenous grafts to provide functional access for 1.5 to 52 months (mean, 15.4 months) after surgery. CONCLUSION: Because no mortality directly resulted from the procedure and the morbidity rate was acceptable, this bypass grafting technique was adequate in maintaining the dialysis access needed by these patients. Because of the magnitude of the procedure, we recommend it only for the occasional patient in whom all other access sites are exhausted and in whom percutaneous dilation and/or stenting has failed. (+info)
Peripheral muscle ergoreceptors and ventilatory response during exercise recovery in heart failure.
Recent studies have suggested that the increased ventilatory response during exercise in patients with chronic heart failure was related to the activation of muscle metaboreceptors. To address this issue, 23 patients with heart failure and 7 normal subjects performed arm and leg bicycle exercises with and without cuff inflation around the arms or the thighs during recovery. Obstruction slightly reduced ventilation and gas exchange variables at recovery but did not change the kinetics of recovery of these parameters compared with nonobstructed recovery: half-time of ventilation recovery was 175 +/- 54 to 176 +/- 40 s in patients and 155 +/- 66 to 127 +/- 13 s in controls (P < 0.05, patients vs. controls, not significant within each group from baseline to obstructed recovery). We conclude that muscle metaboreceptor activation does not seem to play a role in the exertion hyperventilation of patients with heart failure. (+info)
The surgical management of acute limb ischaemia due to native vessel occlusion.
OBJECTIVES: Data from the STILE study have indicated that for patients with subacute limb ischaemia due to native vessel occlusion, surgery is both more effective, and durable than thrombolysis. The purpose of this study was to evaluate the outcome of an aggressive surgical approach in patients presenting with acute limb-threatening ischaemia. DESIGN: Details of patients presenting with salvageable acute limb ischaemia due to native artery occlusion over a 6-year period in a University hospital vascular unit setting were obtained from the vascular audit and the outcome of the surgical management of these patients was analysed. RESULTS: One hundred and seventy-four consecutive patients underwent surgery for acute native vessel limb ischaemia (76% lower, 24% upper limb). Fogarty thrombectomy or embolectomy was initially performed in 153 (89%) patients. Of these, 37 (24%) immediately underwent a further procedure: 28 (18%) had on-table thrombolysis and 14 (9%) underwent vascular reconstruction. Twenty-six patients (15%) underwent further limb salvage surgery within 30 days. Life table analysis demonstrated a limb salvage rate of 88% and 76% at 30 days and 2 years, respectively. Patient survival was 75% and 48% at the same time intervals. CONCLUSIONS: These results demonstrate that a role for aggressive surgical intervention still exists, resulting in high limb salvage rates. (+info)
Ankle-arm index as a predictor of cardiovascular disease and mortality in the Cardiovascular Health Study. The Cardiovascular Health Study Group.
Peripheral arterial disease (PAD) in the legs, measured noninvasively by the ankle-arm index (AAI) is associated with clinically manifest cardiovascular disease (CVD) and its risk factors. To determine risk of total mortality, coronary heart disease, or stroke mortality and incident versus recurrent CVD associated with a low AAI, we examined the relationship of the AAI to subsequent CVD events in 5888 older adults with and without CVD. The AAI was measured in 5888 participants >/=65 years old at the baseline examination of the Cardiovascular Health Study. All participants had a detailed assessment of prevalent CVD and were contacted every 6 months for total mortality and CVD events (including CVD mortality, fatal and nonfatal myocardial infarction, congestive heart failure, angina, stroke, and hospitalized PAD). The crude mortality rate at 6 years was highest (32.3%) in those participants with prevalent CVD and a low AAI (P<0.9), and it was lowest in those with neither of these findings (8.7%, P<0.01). Similar patterns emerged from analysis of recurrent CVD and incident CVD. The risk for incident congestive heart failure (relative risk [RR]=1.61) and for total mortality (RR=1.62) in those without CVD at baseline but with a low AAI remained significantly elevated after adjustment for cardiovascular risk factors. Hospitalized PAD events occurred months to years after the AAI was measured, with an adjusted RR of 5.55 (95% CI, 3.08 to 9.98) in those at risk for incident events. A statistically significant decline in survival was seen at each 0.1 decrement in the AAI. An AAI of <0.9 is an independent risk factor for incident CVD, recurrent CVD, and mortality in this group of older adults in the Cardiovascular Health Study. (+info)