Cerebral activity modulation by extradural motor cortex stimulation in Parkinson's disease: a perfusion SPECT study.

Extradural motor cortex stimulation (EMCS) has been proposed as alternative to deep brain stimulation (DBS) in the treatment of Parkinson's disease (PD). Its mechanisms of action are still unclear. Neuroimaging evidenced motor cortical dysfunction in PD that can be reversed by therapy. We performed left hemisphere EMCS surgery in six advanced PD patients fulfilling CAPSIT criteria for DBS with the exception of age >70 years. After 6 months, we measured regional cerebral blood flow (rCBF) at rest with SPECT and Tc-99m cysteinate dimer bicisate off-medication with stimulator off and on. Clinical assessment included Unified Parkinson's Disease Rating Scale part II and III, Abnormal Involuntary Movement Scale and mean dopaminergic medication dosage. We used statistical parametric mapping for imaging data analysis. Clinically we observed no mean changes in motor scales, although blinded evaluation revealed some benefit in individual patients. We found significant rCBF decrements in the pre-central gyrus, pre-motor cortex and caudate nucleus bilaterally, left prefrontal areas and right thalamus. Perfusion increments were found in cerebellum bilaterally. EMCS determined significant modulation of neuronal activity within the cortico-basal ganglia-thalamo-cortical motor loop in our cohort of advanced PD patients. However, these effects were paralleled by mild and variable clinical efficacy.

Clinical and imaging characterization of a patient with idiopathic progressive ataxia and palatal tremor.

We describe clinical and imaging features of a patient with sporadic progressive ataxia and palatal tremor (PAPT) of unknown etiology. There was hypertrophy of bilateral inferior olivary nuclei with hyperintense T2-weighted signal and mild cerebellar atrophy at brain magnetic resonance imaging. 18F-fluoro-2-desoxy-d-glucose positron emission tomography scanning (FDG-PET) showed hypometabolism in the red nucleus, external globus pallidus and precuneus while FP-CIT-SPECT imaging revealed mild and progressive loss of striatal dopaminergic terminals. Our findings suggest that in idiopathic PAPT involvement of the dentato-rubro-olivary pathway occurs along with some dopaminergic dysfunction.

Striatal dopamine transporter binding in patients with Parkinson's disease and severe occupational hydrocarbon exposure.

We used 123I-Ioflupane SPECT to study striatal dopamine transporter (DAT) binding in 36 Parkinson's disease (PD) patients with history of severe occupational exposure to hydrocarbons. Data were compared with 38 PD patients without exposure history as well as healthy controls. Both PD cohorts showed significant striatal uptake decrements compared with controls. We found significantly lower values in the whole striatum of exposed compared with non-exposed patients (0.83 +/- 0.25 vs. 1.05 +/- 0.39; P = 0.004), more pronounced in the putamen (0.61 +/- 0.24 vs. 0.85 +/- 0.42; P = 0.004). We conclude that severe occupational exposure to hydrocarbons may modify disease course and ultimately accelerate nigro-striatal denervation.

Symptom-limited exercise testing causes sustained diastolic dysfunction in patients with coronary disease and low effort tolerance.

Exercise stress testing is routinely used for the noninvasive assessment of coronary artery disease and is considered a safe procedure. However, the provocation of severe ischemia might potentially cause delayed recovery of myocardial function. To investigate the possibility that maximal exercise testing could induce prolonged impairment of left ventricular function, 15 patients with angiographically proved coronary disease and 9 age-matched control subjects with atypical chest pain and normal coronary arteries were studied. Radionuclide ventriculography was performed at rest, at peak exercise, during recovery and 2 and 7 days after exercise. Ejection fraction, peak filling and peak emptying rates and left ventricular wall motion were analyzed. All control subjects had a normal exercise test at maximal work loads and improved left ventricular function on exercise. Patients developed 1 mm ST depression at 217 +/- 161 s at a work load of 70 +/- 30 W and a rate-pressure product of 18,530 +/- 4,465 mm Hg x beats/min. Although exercise was discontinued when angina or equivalent symptoms occurred, in all patients diagnostic ST depression (greater than or equal to 1 mm) developed much earlier than symptoms. Predictably, at peak exercise patients showed a decrease in ejection fraction and peak emptying and filling rates. Ejection fraction and peak emptying rate normalized within the recovery period, whereas peak filling rate remained depressed throughout recovery (p less than 0.002) and was still reduced 2 days after exercise (p less than 0.02). In conclusion, in patients with severe impairement of coronary flow reserve, maximal exercise may cause sustained impairement of diastolic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness and limits of distal echo-Doppler velocimetric indices for assessing renal hemodynamics in stenotic and non-stenotic kidneys.

BACKGROUND: Distal echo-Doppler velocimetric indices are widely used for revealing the presence of a renal artery stenosis but there is scarce information as to whether they reflect the renal hemodynamics in stenotic and nonstenotic kidneys. OBJECTIVES AND METHODS: We evaluated the pulsatility and resistive indices (PI and RI), acceleration (A) and acceleration time (At) and correlated their values with those of effective renal plasma flow (ERPF), glomerular filtration rate (GFR), renal vascular resistance (RVR) and filtration fraction (FF) estimated by single kidney scintigraphy in 24 kidneys with 70-95% renal artery stenosis (atherosclerotic n = 17, fibromuscular n = 7) and in 27 non-stenotic kidneys (11 contralateral to renal artery stenosis and 16 of patients with essential hypertension). In patients with stenotic kidneys, these measurements were repeated within 7 days after a successful percutaneous transluminal renal angioplasty (PTRA) (in 11 arteries performed in combination with stent implantation). RESULTS: Prior to dilation we found that the stenotic kidneys had significantly lower values of ERPF, GFR and higher RVR than the non-stenotic kidneys and that these hemodynamic alterations were associated with those, also statistically significant, of the four velocimetric indices. In non-stenotic kidneys, there were highly significant relationships between PI and ERPF, and RVR (r = -0.68 and 0.81 respectively P < 0.01); similar relationships were found for RI (r = -0.67 and 0.78 P < 0.01) whereas no such correlations were found between these two velocimetric indices and GFR and FF; also no correlations were found between A and Atand ERPF, GFR, RVR and FF. In stenotic kidneys no significant correlations were found between any of the velocimetric and the hemodynamic indices. Renal artery dilation induced clear cut increments in ERPF, GFR and reduction in RVR in post-stenotic kidneys, which were associated with normalization of all four velocimetric indices. No relationships were observed between the renal hemodynamic and the velocimetric changes induced by dilation; however in post-stenotic kidneys the relationships between PI and RI, ERPF and RVR were restored as in nonstenotic kidneys. CONCLUSIONS: These data indicate that PI and RI can be used to assess ERPF and RVR both in non-stenotic and post-stenotic kidneys; however, none of the velocimetric indices examined in this study can provide valid informations on the renal hemodynamics of stenotic kidneys and on their changes induced by PTRA.

Scintigraphic imaging and absorption of a 5-aminosalicylic acid enema in patients with ileorectal anastomosis.

UNLABELLED: Ileorectal anastomosis (IRA) is a possible surgical treatment for hyperacute and drug-unresponsive forms of ulcerative colitis (UC). UC relapses in the rectal remnant usually are prevented by chronic administration of 5-aminosalicylic acid (5-ASA) in topical formulations. The relationships between intestinal absorption and pattern of luminal spread of 5-ASA enemas are still unknown in patients with IRA. We correlated the absorption of a 5-ASA enema with its spread in the distal bowel of patients with IRA as assessed by 99mTc radioenema imaging. METHODS: Eight patients with UC in remission and previous IRA received a therapeutic 50-mL 5-ASA enema labeled with 99mTc-sulfer colloid. Absorbed 5-ASA and its major metabolite, acetyl 5-ASA, were measured in plasma, and dynamic images of radiolabeled enema were obtained for 6 h. The retrograde ileal spread (RIS) was determined and expressed as percentage of total enema radioactivity. Plasma levels of 5-ASA and acetyl 5-ASA were measured in six healthy volunteers after administration of the same enema volume with no radiolabeling. RESULTS: The mean 5-ASA plasma level was 0.70 microg/mL (range 0.37-0.95 microg/mL) in patients and 0.96 microg/mL (range 0.78-1.16 microg/mL) in healthy volunteers (P = not significant), and the mean acetyl 5-ASA plasma levels were 0.89 microg/mL (range 0.44-1.19 microg/mL) and 0.84 microg/mL (range 0.51-1.02 microg/mL), respectively (P = not significant). Radioenema imaging allows RIS assessment of patients with IRA. The mean value was 8.5% (range 2%-19.3%) of administered radioactivity, which correlated significantly with the total absorption of 5-ASA in the IRA group (P = 0.033, linear correlation test). Rectal wall contractions recognized by dynamic radioenema imaging were defined as a common cause of RIS episodes. CONCLUSION: In IRA patients, 5-ASA plasma levels were similar to those in healthy volunteers after administration in enema. Only part of a 50-mL 5-ASA enema reaches the ileum, and radiolabeled imaging shows the degree and number of these RIS episodes. The absorption of 5-ASA can increase in patients compared with healthy volunteers, in the presence of either occasional but significant ileal spread associated with postural factors and abdominal wall contraction or multiple moderate episodes of radioenema backdiffusion related to rectal wall motility.

Angioplasty of atherosclerotic and fibromuscular renal artery stenosis: time course and predicting factors of the effects on renal function.

The effects of percutaneous transluminal renal angioplasty (PTRA) on the renal function of stenotic kidneys are usually assessed by evaluating the changes in serum creatinine, which is quite a rough indicator of glomerular filtration rate (GFR). In 27 hypertensive patients with 19 atherosclerotic and 11 fibromuscular significant renal artery stenoses, we investigated with renal scintigraphy the short-term (5 days) and long-term (10 months) effects of a technically successful PTRA (in seven cases combined with a stent implantation) on GFR of the stenotic and contralateral kidneys; these measurements were combined with those of plasma renin activity (PRA) and of angiotensin II (AII). We found that in short-term studies after PTRA GFR rose from 29.7 +/- 3.5 to 34.6 +/- 3.1 mL/min and from 36.9 +/- 4.0 to 45.1 +/- 4.3 mL/min, respectively, in atherosclerotic and fibromuscular poststenotic kidneys. In long-term studies GFR further and significantly increased, to 37.8 +/- 3.2 mL/min in the former group, whereas it stabilized in the latter group (46.0 +/- 3.6 mL/min). In patients with fibromuscular stenosis these changes in GFR were associated with clear-cut reductions in blood pressure (BP), PRA, and AII; these decrements also occurred in patients with atherosclerotic stenosis but to a much lesser extent. We also found that in short- and long-term studies the percent of PTRA-induced increments of GFR in the poststenotic kidneys were inversely correlated with the baseline values of GFR. In addition, the absolute and percent increments of GFR were positively correlated with the basal levels of AII. Thus the time course of the improvement in GFR after angioplasty may differ in kidneys, depending on the etiology of the stenosis, in that in those with fibromuscular stenosis it was entirely apparent within a few days whereas in those with atherosclerotic stenosis it required several months to be fully expressed. Also, it appears that the more compromised kidneys are those that benefit most from the dilatation and that AII levels are useful indicators of the possibility that the stenotic kidney will have a favorable functional outcome in terms of restoration of renal blood flow.

Extracorporeal circulation as a new experimental pathway for myoblast implantation in mdx mice.

The deficiency of dystrophin, a sarcolemmal associated protein, is responsible for Duchenne muscular dystrophy (DMD). Gene replacement is attractive as a potential therapy. In this article, we describe a new method for myoblast transplantation and expression of dystrophin in skeletal muscle tissue of dystrophin-deficient mdx mouse through iliac vessels extracorporeal circulation. We evaluated the extracorporeal circulation as an alternative route of delivering myoblasts to the target tissue. Two series of experiments were performed with the extracorporeal circulation. In a first series, L6 rat myoblasts, transfected with LacZ reporter gene, were perfused in limbs of 15 rats. In the second series, the muscle limbs of three 6-8-week-old mdx were perfused with myoblasts of donor C57BL10J mice. Before these perfusions, the right tibialis anterior (TA) muscle of the rats and mdx was injected three times at several sites with bupivacaine (BPVC) and hyaluronidase. The ability of injected cells to migrate in the host tissue was assessed in rats by technetium-99m cell labeling. No radioactivity was detected in the lungs, bowels, and liver of animals treated with extracorporeal circulation. The tissue integration and viability of the myoblasts were ultimately confirmed by genetic and histochemical analysis of LacZ reporter gene. Following a single extracorporeal perfusion of myoblasts from donor C57BL10J, sarcolemmal expression of dystrophin was observed in clusters of myofibers in tibialis anterior muscles previously treated with BPVC and hyaluronidase. Furthermore, large clusters of dystrophin-positive fibers were observed in muscles up to 21 days after repeated treatments. These clusters represented an average of 4.2% of the total muscle fibers. These results demonstrate that the extracorporeal circulation allows selective myoblast-mediated gene transfer to muscles, opening new perspectives in muscular dystrophy gene therapy.

Focal cognitive impairment in mitochondrial encephalomyopathies: a neuropsychological and neuroimaging study.

Mitochondrial encephalomyopathies (ME) are a multisystemic group of diseases characterized by a wide range of biochemical and genetic mitochondrial defects with a variable mode of inheritance. We studied the neuropsychological profile, magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) data in a group of ME patients in order to look for common or specific cognitive defects and a possible correlation with related brain areas. Three main cognitive areas were assessed: general intelligence, memory functions and visuo-perceptual skills. Our sample included 16 ME patients (nine males, seven females) aged 25-68 years (mean age 45.2, SD 13.0). No sign of mental deterioration was found in the group of elderly subjects. Despite subjects showing no global cognitive impairment they scored lower in nonverbal versus verbal tasks. Visuo-spatial skills and short-term memory were selectively impaired. There was no correlation between neuropsychological results and age, illness duration, age of onset, clinical phenotypes, genetic mitochondrial alterations and pharmacological therapy. The most frequent SPECT pattern observed was the hypoperfusion of temporal lobes, with a direct localization in the temporal cortex and with prevalent mesial involvement. The neuropsychological profile and SPECT imaging revealed similarities with focal defects.

Biodistribution studies of 99mTc-labeled myoblasts in a murine model of muscular dystrophy.

The purpose of this study was twofold: first, to evaluate the myoblast labeling of various 99mTc complexes and to select the complex that best accomplishes this labeling, and second to evaluate the biodistribution of myoblasts labeled with this complex using mice with MDX muscular dystrophy (the murine homologue of Duchenne's muscular dystrophy). The following ligands were used to prepare the corresponding 99mTc complexes: hexakis-methoxy-isobutyl-isonitrile (MIBI), bis(2-ethoxyethyl)diphosphinoethane (Tf), (RR,SS)-4,8-diaza-3,6,6,9-tetramethyl-undecane-2,10-dione-bisoxime (HM-PAO), bis(N-ethyl)dithiocarbamate (NEt), and bis(N-ethoxy, N-ethyl)dithiocarbamate (NOEt). One million murine myoblasts were incubated for 30-60 minutes with 5 mCi of each of the 99mTc complexes prepared from the above ligands. Viability was assessed by microscopic counting after trypan blue staining, and the radioactivity absorbed in the cells was measured after centrifugation. The compound with the highest uptake in cellular pellets was [99mTc]N-NOEt. The biodistribution of myoblasts labeled with this complex was evaluated after intraaortic injection in dystrophic mice. Such an approach has the potential of effecting widespread gene transfer through the bloodstream to muscles lacking dystrophin.

Unilateral periventricular nodular heterotopia associated with diffuse areas of cerebral functional abnormalities.

A 17-year-old boy with polymorphic simple and complex partial seizures is described. Magnetic resonance imaging revealed a unilateral periventricular nodular heterotopia near the occipital ventricular right horn. Interictal and ictal electroencephalographic recordings showed bilateral specific epileptiform anomalies in the occipital region and asynchronous slow waves in frontal areas. Single photon emission computed tomography documented a reduction in regional cerebral blood flow in an area of the left occipital cortex and a symmetric increase in tracer uptake in the frontal lobes. The neuropsychologic assessment revealed a dysfunction of the frontal associative areas. Data collected led the authors to suspect a more diffuse cortical dysfunction than the nodular heterotopia revealed on magnetic resonance imaging.

Functional neuroimaging (PET and SPECT) in the selection and assessment of patients with Parkinson's disease undergoing deep brain stimulation.

Deep brain Stimulation (DBS) is an effective treatment for patients with advanced Parkinson's disease (PD) and motor complications who can no longer be improved by adjustment of medical therapy. Selection of surgery candidates and follow-up after surgery are critical for good outcome. Functional neuroimaging can help in the clinical assessment of these patients. We have used single photon emission computed tomography (SPECT) and the tracer ECD to measure regional cerebral blood flow before and 6 months after DBS of the subthalamic nucleus (STN) in 20 patients with advanced PD. We found a significant increase in the anterior cingulate/supplementary motor cortex in the 12 good responders (change in off unified UPDRS >50%). Conversely, patients with poor response (n=8; change in off UPDRS-III <50% following DBS) revealed a significant worsening of cortical hypoperfusion particularly in the prefrontal areas. No flow decrements were detected in the basal ganglia and in the thalamus in both groups during DBS stimulation suggesting that DBS does not have a "lesion like" effect. If DBS stimulates and does not inactivate STN projection neurons, flow reduction in the poor responders may be secondary to increased inhibitory basal ganglia output.

High cerebral perfusion pressure improves low values of local brain tissue O2 tension (PtiO2) in focal lesions.

Arterial hypertension is widely applied to improve regional cerebral blood flow (rCBF). We measured local brain tissue O2 pressure (PtiO2) in low density lesions at computerized tomography (CT) of the head before and after manipulation of mean arterial pressure (MAP) in order to increase cerebral perfusion pressure (CPP). Nine patients, 7 subarachnoid hemorrhage (SAH), 1 severe head injury, 1 meningeoma, were included in our study. A flexible polarographic microcatheter for PtiO2 measurement was placed at the border of the low density area found at CT. PtiO2 was continuously measured for 615 hours. Hypoperfusion in low density areas was detected by perfusional single photon emission computed tomography (SPECT). We recorded 22 episodes of induced or spontaneous increase of MAP. Initial PtiO2 regularly improved after the CPP increase (r2 0.74 in induced episodes). Low PtiO2 showed a greater percent increase for unitary changes of CPP than normal-high PtiO2. Baseline PtiO2 below 20 mm Hg was associated with normal CPPs; 5 readings of PtiO2 below 20 mm Hg normalized when a higher CPP was obtained. Our results show that in ischemic areas PtiO2 is dependent on CPP suggesting both a derangement of pressure autoregulation and high regional cerebrovascular resistences (CVRs). Low PtiO2 was associated with normal CPP, thus indicating that CPP could be an inadequate estimate of rCBF in focal ischemic areas. Arterial hypertension, capable of increasing CPP above normal values, appeared useful in normalizing tissue oxygenation in ischemic areas.

Atypical Parkinsonism Revealing a Late Onset, Rigid and Akinetic Form of Huntington's Disease.

Huntington's disease (HD) is a rare hereditary neurodegenerative disorder characterized in over 90 percent of cases by chorea as the presenting motor symptom. We report a 54-year-old male who presented with Parkinsonism as the initial symptom of the disease. Genetic analysis revealed expansion of 40 CAG repeats, and brain MRI showed both severe caudate nuclei and cortical atrophy. Single-photon emission computed tomography (SPECT) imaging of the dopamine transporter showed nigrostriatal pathway degeneration. Here, we also describe his 2 years of clinical followup after ensuing dopaminergic stimulation.

Brain SPECT imaging in multiple system atrophy.

Clinical diagnosis of multiple system atrophy (MSA) relays on signs and symptoms that are often difficult to identify particularly at early stage. Indeed neuropathological studies have demonstrated that MSA is the first cause of misdiagnosis in a cohort of patients presenting with parkinsonian features. Dopamine transporter imaging (DAT) shows striatal decrements in both MSA and Parkinson's disease (PD) making it not sensitive for differential diagnosis. Studies of dopamine D2 receptors with IBZM may help revealing striatal degeneration but a large overlap exist particularly if PD patients with advanced disease are included. We have measured brain flow with technetium-99m ethyl cysteinate dimer (ECD-SPECT) in 36 MSA patients and compared it with 43 PD and 39 age-matched controls. Using Statistical Parametric Mapping (SPM99) we found areas of significant reduced perfusion in the striatum, brain stem and cerebellum in MSA compared to the other groups. We believe that ECD-SPECT imaging may offer significant advantages compared to other imaging techniques in the assessment of neuronal degeneration in MSA and may help the clinician in the diagnostic characterization of patients presenting with atypical parkinsonism.