Fredrik Karlsson

Platelet aggregation and aspirin non‐responsiveness increase when an acute coronary syndrome is complicated by an infection

Background: Epidemiologic studies have shown that there is an association between acute respiratory infection and acute coronary syndrome. The aim of this study was to analyze the thrombotic risk, assessed by platelet aggregation and aspirin non‐responsiveness, in patients with an acute coronary syndrome complicated by an infection. Methods: Patients with an acute coronary syndrome who were admitted to the intensive care unit and hospitalized for at least 3 days in 2002 and 2003 were eligible for the study. Three hundred and fifty‐eight patients were included, of whom 66 had an infection during their hospital stay. Platelet aggregation was analyzed by an aggregometer using laser light (PA‐200, laser light scattering). Aspirin non‐responsiveness was defined as a closure time of ≤193 s measured by PFA‐100. Results: Platelet aggregation was more pronounced during an infectious complication (P < 0.001). The subgroups of patients with persistent fever, urinary tract infection, and pneumonia all had a higher level of aggregates than the group of patients without an infection (P = 0.007, P = 0.04, and P = 0.01, respectively). Aspirin non‐responsiveness was more frequent in the group of subjects with pneumonia compared with those without an infection, 90% vs. 46% (P = 0.006). The CRP levels were independently associated with platelet aggregation and aspirin non‐responsiveness (P < 0.001, P < 0.001, respectively). Conclusion: An infectious complication during the course of an acute coronary syndrome leads to more pronounced platelet aggregation. Aspirin non‐responsiveness is more frequent in severe infections, such as pneumonia. CRP is an independent predictor of platelet aggregation and aspirin non‐responsiveness in the setting of an acute coronary syndrome.

Deep Brain Stimulation of Caudal Zona Incerta and Subthalamic Nucleus in Patients with Parkinson's Disease: Effects on Diadochokinetic Rate

The hypokinetic dysarthria observed in Parkinsons disease (PD) affects the range, speed, and accuracy of articulatory gestures in patients, reducing the perceived quality of speech acoustic output in continuous speech. Deep brain stimulation (DBS) of the subthalamic nucleus (STN-DBS) and of the caudal zona incerta (cZi-DBS) are current surgical treatment options for PD. This study aimed at investigating the outcome of STN-DBS (7 patients) and cZi-DBS (7 patients) in two articulatory diadochokinesis tasks (AMR and SMR) using measurements of articulation rate and quality of the plosive consonants (using the percent measurable VOT metric). The results indicate that patients receiving STN-DBS increased in articulation rate in the Stim-ON condition in the AMR task only, with no effect on production quality. Patients receiving cZi-DBS decreased in articulation rate in the Stim-ON condition and further showed a reduction in production quality. The data therefore suggest that cZi-DBS is more detrimental for extended articulatory movements than STN-DBS.

Deep Brain Stimulation of Caudal Zona Incerta and Subthalamic Nucleus in Patients with Parkinson's Disease: Effects on Voice Intensity

Deep brain stimulation of the subthalamic nucleus (STN-DBS) in patients with Parkinsons disease (PD) affects speech inconsistently. Recently, stimulation of the caudal zona incerta (cZi-DBS) has shown superior motor outcomes for PD patients, but effects on speech have not been systematically investigated. The aim of this study was to compare the effects of cZi-DBS and STN-DBS on voice intensity in PD patients. Mean intensity during reading and intensity decay during rapid syllable repetition were measured for STN-DBS and cZi-DBS patients (eight patients per group), before- and 12 months after-surgery on- and off-stimulation. For mean intensity, there were small significant differences on- versus off-stimulation in each group: 74.2 (2.0) dB contra 72.1 (2.2) dB (P = .002) for STN-DBS, and 71.6 (4.1) dB contra 72.8 (3.4) dB (P = .03) for cZi-DBS, with significant interaction (P < .001). Intensity decay showed no significant changes. The subtle differences found for mean intensity suggest that STN-DBS and cZi-DBS may influence voice intensity differently.

Vowel formant dispersion as a measure of articulation proficiency

The articulatory range of a speaker has previously been estimated by the shape formed by first and second formant measurements of produced vowels. In a majority of the currently available metrics, formant frequency measurements are reduced to a single estimate for a condition, which has adverse consequences for subsequent statistical testing. Other metrics provide estimates of size of vowel articulation changes only, and do not provide a method for studying the direction of the change. This paper proposes an alternative approach. Vowel formant frequencies are redefined as vectors originating from a defined center point of the vowel space fixed to a basic three-vowel frame. The Euclidean length of the vectors, the vowel formant dispersion (VFD), can be compared across conditions for evidence of articulatory expansions or reductions across conditions or speaker groups. Further, the angle component of the vowel vectors allows for analyses of direction of the reduction or expansion. Based on the range of investigations afforded by the VFD metric, and simulation experiments that compare its statistical properties with those of other proposed metrics, it is argued that the VFD procedure offers an enhanced view of vowel articulation change over rival metrics.

Perceived articulatory precision in patients with Parkinson’s disease after deep brain stimulation of subthalamic nucleus and caudal zona incerta

Abstract The effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and caudal zona incerta (cZi) on speech articulation in patients with Parkinson’s disease (PD) was investigated. Read speech samples were collected from nine patients with STN-DBS and 10 with cZi-DBS. The recordings were made pre-operatively and 12 months post-operatively with stimulator on and off (on medication). Blinded, randomised, repeated perceptual assessments were performed on words and isolated fricatives extracted from the recordings to assess (1) overall articulatory quality ratings, (2) frequency of occurrence of misarticulation patterns and (3) fricative production. Statistically significant worsening of articulatory measures on- compared with off-stimulation occurred in the cZi-DBS group, with deteriorated articulatory precision ratings, increased presence of misarticulations (predominately altered realisations of plosives and fricatives) and a reduced accuracy in fricative production. A similar, but not significant, trend was found for the STN-DBS group.

Word-level intelligibility after caudal zona incerta stimulation for Parkinson's disease.

To investigate the effect of caudal zona incerta‐deep brain stimulation (cZi‐DBS) on word‐level speech intelligibility in patients with Parkinsons disease, under both an optimal listening condition and a simulated more naturalistic listening condition.

Articulatory Closure Proficiency in Patients with Parkinson's Disease Following Deep Brain Stimulation of the Subthalamic Nucleus and Caudal Zona Incerta.

PURPOSE The present study aimed at comparing the effects of deep brain stimulation (DBS) treatment of the subthalamic nucleus (STN) and the caudal zona incerta (cZi) on the proficiency in achieving oral closure and release during plosive production of people with Parkinsons disease. METHOD Nineteen patients participated preoperatively and 12 months after DBS surgery. Nine patients had implantations in the STN, 7 bilaterally and 2 unilaterally (left). Ten had bilateral implantations in the cZi. Postoperative examinations were made off and on stimulation. All patients received simultaneous L-dopa treatment in all conditions. For a series of plosives extracted from a reading passage, absolute and relative measures of duration of frication and amplitude of plosive release were compared between conditions within each treatment group. RESULTS Relative duration of frication increased in voiceless plosives in the on-stimulation condition in cZi patients. Similar trends were observed across the data set. Duration of prerelease frication and the release peak prominence increased in voiceless plosives on stimulation for both groups. CONCLUSION The increased release prominence suggests that patients achieved a stronger closure gesture because of DBS but that the increased energy available resulted in increased frication.

Voice Tremor in Patients With Essential Tremor : Effects of Deep Brain Stimulation of Caudal Zona Incerta

OBJECTIVES The present study aimed at evaluating the effect of deep brain stimulation (DBS) of the caudal zona incerta (cZi) on voice tremor in patients with essential tremor (ET). STUDY DESIGN This is a prospective nonrandomized design with consecutive patients. METHODS Twenty-six patients operated with cZi DBS were evaluated under two conditions: without stimulation (Stim OFF) and with stimulation (Stim ON). Voice tremor was assessed on the basis of recordings of sustained vowel productions using a four-point rating scale in a blinded and randomized procedure. Averaged values of multiple assessments for each stimulus were used in statistical testing. The group of patients with voice tremor in Stim OFF was analyzed separately from the group of patients without voice tremor. RESULTS Voice tremor was significantly reduced on stimulation compared with off for the subgroup with initial voice tremor. Voice tremor prevalence was found to be 50% (13 patients). Individual differences in voice tremor outcome were noticeable. Six of the patients with voice tremor at baseline improved substantially by cZi DBS treatment. CONCLUSIONS On the group level, voice tremor in patients with ET was found to reduce when stimulating the cZi. Bilateral stimulation was indicated to be more effective in reducing voice tremor than unilateral stimulation. However, individual voice tremor outcomes suggest that not all patients benefit from cZi DBS. Severity of voice tremor at baseline may not be a good predictor of voice tremor outcome after cZi DBS. Patients should be informed before surgery regarding individual differences in response to DBS treatment.

The impact of platelet function or C-reactive protein, on cardiovascular events after an acute myocardial infarction

BackgroundRecurrent cardiovascular events following acute myocardial infarction (AMI) are common. The purpose of this study was to evaluate the impact of platelet aggregation, PFA-100 closure times and peak C-reactive protein (CRP), respectively, on the occurrence of death, myocardial infarction and ischemic cerebral events after an AMI. Furthermore, to examine the relationship between the platelet function tests and peak CRP.MethodsThree hundred and thirty-four patients with AMI were included in the study. Platelet aggregation was analyzed by an aggregometer using laser light (PA-200). The state of high residual platelet reactivity was defined as normal closure times (PFA-100) during treatment with aspirin.ResultsThe fourth quartile of peak CRP was associated with poorer outcome as compared to the first quartile in a multivariate Cox-regression analysis, with a hazard ratio of 2.0 (95% CI 1.1–3.7) for the occurrence of death, myocardial infarction and ischemic cerebral events. The fourth quartile of peak CRP (>64.6 mg/l) was associated with platelet aggregation (p < 0.001, adjusted R2 = 0.13) and high residual platelet reactivity, in a multivariate model, with an odds ratio of 2.9 (CI 95% 1.3–6.8), as compared to the first quartile. Neither the highest quartile of platelet aggregation nor the state of high residual platelet reactivity predicted new cardiovascular events.ConclusionIn patients with myocardial infarction, measured peak CRP is associated with new cardiovascular events. Despite an association with peak CRP neither more pronounced platelet aggregation nor PFA-100 closure times independently predict new cardiovascular events.

Speech intelligibility in Parkinson's disease patients with zona incerta deep brain stimulation

To investigate the effects of l‐dopa (Levodopa) and cZi‐DBS (deep brain stimulation in caudal zona incerta) on spontaneous speech intelligibility in patients with PD (Parkinsons disease).