The Impact of Palliative Decompressive Gastrostomy Tube Placement on Patients and Their Caregivers: A Mixed Methods Analysis.

BACKGROUND: Palliative decompressive gastrostomy tubes are intended to relieve the severe physical symptoms of malignant small bowel obstruction (SBO) near the end of life. The objective of this study was to assess the impact of palliative decompressive gastrostomy tube on patient and caregiver well-being. PATIENTS AND METHODS: We prospectively enrolled patients with a malignant SBO and their caregivers at the time of informed consent for decompressive gastrostomy tube placement. We collected the Edmonton Symptom Assessment Scale (ESAS) and the Functional Assessment of Chronic Illness Therapy-Palliative (FACIT-Pal-14) surveys from patients at baseline and at 2-week post-procedure follow-up. The Caregiver Burden Scale survey was administered to caregivers at baseline. Survey scores were compared using paired t-tests. We also conducted semistructured interviews with patients and their caregivers at two-week follow-up until thematic saturation was reached. Content analysis was used to identify themes with two independent coders. RESULTS: We enrolled 15 patient-caregiver dyads. Preprocedure, the median caregiver burden scale score was 37.5 (significant burden ≥ 21). Eight patients (53%) survived to 2 weeks; among these patients, median ESAS scores (51 versus 43.5, p < 0.001) and median FACIT-Pal-14 scores (22 versus 32, p = 0.015) were significantly improved at 2-week follow-up. Interviews revealed three major themes: improved symptom management, new stressors, and opportunities for better education and resources. CONCLUSIONS: Decompressive gastrostomy tubes effectively alleviated symptoms in patients with inoperable malignant SBOs. This palliative intervention may provide greater benefit if performed earlier, and caregivers and patients need improved resources and education for tube management to minimize added stressors.

Safety of elective enteral access in elderly patients: a comparative analysis of perioperative risk.

BACKGROUND: Elderly patients can experience torpid hospitalization that is often characterized by malnutrition. In this setting, enteral feeding may facilitate improvement in nutritional status. This study aimed to compare the perioperative outcomes between elderly (age of ≥65 years old) and nonelderly (age of <65 years old) patients undergoing elective enteral access placement. METHODS: Adult patients who underwent enteral access procedures between 2018 and 2020 at a tertiary care facility were retrospectively reviewed. Differences in baseline characteristics between nonelderly and elderly patients were adjusted using entropy-balanced weights. Subsequently, multivariate logistic and linear regression models were developed to evaluate the association between elderly status and outcomes of interest. RESULTS: Overall, 914 patients with enteral access met the inclusion criteria, of whom 471 (51.5%) were elderly. Elderly patients more commonly received percutaneous gastrostomy and had a higher burden of comorbidities as measured using the Charlson Comorbidity Index than nonelderly patients. Multivariate risk adjustment generated a strongly balanced distribution of baseline covariates between patient groups. After adjustment, despite no significant association with inhospital mortality, reoperation, or time to feeding goals, elderly status was linked to an approximately 8-day reduction in length of stay (95% CI, -14.28 to -2.30; P = .007) and significantly lower odds of total parenteral nutrition (adjusted odds ratio [AOR], 0.59; 95% CI, 0.37-0.94; P = .026) and nonelective readmission (AOR, 0.65; 95% CI, 0.49-0.86; P = .003). In addition, elderly status was associated with significantly greater odds of nonhome discharge (AOR, 1.58; 95% CI, 1.17-2.13; P = .003). CONCLUSION: Despite having more comorbidities than their nonelderly counterparts, elderly patients experienced favorable nutritional and perioperative outcomes after enteral access placement.

Outcomes in Enteral Access Based on Specialty and Approach: A Single-Center Three-Year Experience.

INTRODUCTION: Interventional radiologic, endoscopic, and surgical approaches are commonly utilized to establish durable enteral access in adult patients. The purpose of this study is to examine differences in nutritional outcomes in a large cohort of patients undergoing enteral access creation. METHODS: Adult patients who underwent enteral access procedures by interventional radiologists, gastroenterologists, and surgeons between 2018 and 2020 at a single institution were reviewed. Included access types were percutaneous endoscopic gastrostomy (PEG), open or laparoscopic gastrostomy, laparoscopic jejunostomy, and percutaneous gastrostomy (perc-G), percutaneous jejunostomy , or primary gastrojejunostomy. RESULTS: 912 patients undergoing enteral access cases met the criteria for inclusion. PEGs and perc-Gs were the most common procedures. PEGs had higher Charlson scores (4.5 [3.0-6.0] versus 2.0 [1.0-2.0], P = 0.007) and lower starting albumin (3.0 [2.6-3.4] versus 3.6 [3.5-3.8] g/dL, P < 0.0001). Time to goal feeds (4 [2-6] vs 4 [3-5] d, P = 0.970), delta prealbumin (3.6 [0-6.5] versus 6.2 [2.3-10] mg/L, P = 0.145), time to access removal (160 [60-220] versus 180 [90-300] d, P = 0.998), and enteral access-related complications (19% versus 16%, P = 0.21) between PEG and perc-G were similar and differences were not statistically significant. A greater percent change in prealbumin was noted for perc-G (10 [-3-20] versus 41.7% [11-65], P = 0.002). CONCLUSIONS: Despite having higher Charlson scores and worse preoperative nutrition, there is a similar incidence of enteral access-related complications, time to goal feeds, delta prealbumin, or time to access removal between PEG and perc-G patients. Our data suggest that access approach should be made on an individual basis, accounting for anatomy and technical feasibility.

Impact of Artificial Intelligence-Assisted Indication Selection on Appropriateness Order Scoring for Imaging Clinical Decision Support.

PURPOSE: The aim of this study was to assess appropriateness scoring and structured order entry after the implementation of an artificial intelligence (AI) tool for analysis of free-text indications. METHODS: Advanced outpatient imaging orders in a multicenter health care system were recorded 7 months before (March 1, 2020, to September 21, 2020) and after (October 20, 2020, to May 13, 2021) the implementation of an AI tool targeting free-text indications. Clinical decision support score (not appropriate, may be appropriate, appropriate, or unscored) and indication type (structured, free-text, both, or none) were assessed. The χ2 and multivariate logistic regression adjusting for covariables with bootstrapping were used. RESULTS: In total, 115,079 orders before and 150,950 orders after AI tool deployment were analyzed. The mean patient age was 59.3 ± 15.5 years, and 146,035 (54.9%) were women; 49.9% of orders were for CT, 38.8% for MR, 5.9% for nuclear medicine, and 5.4% for PET. After deployment, scored orders increased to 52% from 30% (P < .001). Orders with structured indications increased to 67.3% from 34.6% (P < .001). On multivariate analysis, orders were more likely to be scored after tool deployment (odds ratio [OR], 2.7, 95% CI, 2.63-2.78; P < .001). Compared with physicians, orders placed by nonphysician providers were less likely to be scored (OR, 0.80; 95% CI, 0.78-0.83; P < .001). MR (OR, 0.84; 95% CI, 0.82-0.87) and PET (OR, 0.12; 95% CI, 0.10-0.13) were less likely to be scored than CT (; P < .001). After AI tool deployment, 72,083 orders (47.8%) remained unscored, 45,186 (62.7%) with free-text-only indications. CONCLUSIONS: Embedding AI assistance within imaging clinical decision support was associated with increased structured indication orders and independently predicted a higher likelihood of scored orders. However, 48% of orders remained unscored, driven by both provider behavior and infrastructure-related barriers.

Myofibroblastoma in the Liver: A Case Report and Review of Literature.

Myofibroblastoma is a rare benign mesenchymal tumor first described in the breast. It is also known as mammary-type myofibroblastoma outside of the breast, more frequently located along the embryonic milk line. Exceptionally, myofibroblastoma can occur at visceral locations. We present a case of myofibroblastoma detected incidentally in the liver. A well-circumscribed mass, grossly measuring 6.2 cm in the liver parenchyma, was found on imaging studies. Histologically, the lesion is characterized by benign spindle cells in a hyalinized collagenous stroma, with positive staining for SMA and ER, focal positivity for CD34, negative for desmin, and loss of RB1. This rare tumor at such an unusual location makes it diagnostically challenging, especially on core biopsy of the lesion. To our knowledge, this is the second case of myofibroblastoma in the liver reported in the English literature and the first such case with a detailed pathology description.

Changes in perfusion angiography after IVC filter placement and retrieval.

Inferior vena cava (IVC) filters are posited to effect flow dynamics, causing turbulence, vascular remodeling and eventual thrombosis; however, minimal data exists evaluating hemodynamic effects of IVC filters in vivo. The purpose of this study was to determine differences in hemodynamic flow parameters acquired with two-dimension (2D)-perfusion angiography before and after IVC filter placement or retrieval. 2D-perfusion images were reconstructed retrospectively from digital subtraction angiography from a cohort of 37 patients (13F/24M) before and after filter placement (n = 18) or retrieval (n = 23). Average dwell time was 239.5 ±â€…132.1 days. Changes in the density per pixel per second within a region of interest (ROI) were used to calculate contrast arrival time (AT), time-to-peak (TTP), wash-in-rate (WIR), and mean transit time (MTT). Measurements were obtained superior to, inferior to, and within the filter. Differences in hemodynamic parameters before and after intervention were compared, as well as correlation between parameters versus filter dwell time. A P value with Bonferroni correction of <.004 was considered statistically significant. After placement, there was no difference in any 2D-perfusion variable. After retrieval, ROIs within and inferior to the filter showed a significantly shorter TTP (1.7 vs 1.4 s, P = .004; 1.5 vs 1.3 s, P = .001, respectively) and MTT (1.7 vs 1.4 s, P = .003; 1.5 vs 1.2 s, P = .002, respectively). Difference in variables showed no significant correlation when compared to dwell time. 2D-perfusion angiography is feasible to evaluate hemodynamic effects of IVC filters in vivo. TTP and MTT within and below the filter after retrieval were significantly changed, without apparent correlation to dwell time, suggesting a functional hemodynamic delay secondary to filter presence.

Transjugular intrahepatic portosystemic shunt for the management of symptomatic malignant pseudocirrhosis.

Background: Pseudocirrhosis is defined by radiologic changes of the liver parenchyma secondary to metastatic disease and/or cancer treatments, and portends a high rate of morbidity and mortality from sequelae of portal hypertension. Transjugular intrahepatic portosystemic shunt (TIPS) is an effective treatment for portal hypertension; however, TIPS is relatively contraindicated in the setting of hepatic metastases. The study aims to determine the technical efficacy and clinical outcomes of patients undergoing TIPS for symptomatic pseudocirrhosis. Methods: Retrospective analysis of patients with hepatic malignancy who underwent TIPS between 2008 and 2020 at a single tertiary care center. Patients with imaging findings of pseudocirrhosis and without history of primary liver malignancy or confounding causes of cirrhosis were included. West Haven scores assessing hepatic encephalopathy were obtained from chart review. Technical success was defined as successful TIPS creation with reduction in the portosystemic gradient (PSG). Clinical success was defined as resolution of variceal bleeding and/or ascites. Results: Nine patients (4 female/5 male), average (± SD) age 61.2±9.5 years with metastatic pseudocirrhosis were included for analysis. Primary malignancy was colorectal adenocarcinoma (n=5), neuroendocrine tumor (n=3), and malignant endothelial hemangioendothelioma (n=1). Average Model for End Stage Liver Disease (MELD-Na) score was 15.7±3.7. Technical success was 8/9 (89%) with average PSG reduced from 23.5±11.0 to 6.5±2.8 mmHg (P=0.001). Clinical success was 6/9 (67%). Two patients required TIPS revision after initial clinical success. Mild-moderate HE occurred in 6/9 patients post TIPS (67%), with a highest West Haven score of 2. Time from TIPS to death for acute variceal bleeding and ascites was 4.9±4.2 and 12±16.5 months, respectively. Cause of death was disease progression (n=5), variceal bleeding (n=1), or unavailable (n=2). Conclusions: TIPS in the setting of malignant pseudocirrhosis can be created safely with similar clinical outcomes to TIPS performed for benign disease. Rates of low-grade hepatic encephalopathy may be higher amongst patients undergoing TIPS for pseudocirrhosis.

Endovascular management of traumatic pseudoaneurysms.

BACKGROUND: Pseudoaneurysms (PAs) caused by traumatic injury to the arterial vasculature have a high risk of rupture, leading to life-threatening hemorrhage and mortality, requiring urgent treatment. The purpose of this study was to determine the technical and clinical outcomes of endovascular treatment of visceral and extremity traumatic pseudoaneurysms. METHODS: Clinical data were retrospectively collected from all patients presenting for endovascular treatment of PAs between September 2012 and September 2018 at a single academic level one trauma center. Technical success was defined as successful treatment of the PA with no residual filling on post-embolization angiogram. Clinical success was defined as technical successful treatment with no rebleeding throughout the follow-up period and no reintervention for the PA. RESULTS: Thirty-five patients (10F/25M), average age (± stdev) 41.7 ± 20.1 years, presented with PAs secondary to blunt (n = 31) or penetrating (n = 4) trauma. Time from trauma to intervention ranged from 2 h - 75 days (median: 4.4 h, IQR: 3.5-17.1 h) with 27 (77%) of PAs identified and treated within 24 h of trauma. Average hospitalization was 13.78 ± 13.4 days. Ten patients underwent surgery prior to intervention. PA number per patient ranged from 1 to 5 (multiple diffuse). PAs were located on the splenic (n = 12, 34.3%), pelvic (n = 11, 31.4%), hepatic (n = 9, 25.7%), upper extremity/axilla (n = 2, 5.7%), and renal arteries (n = 1, 2.9%). Technical success was 85.7%. Clinical success was 71.4%, for technical failure (n = 5), repeat embolization (n = 1) or post-IR surgical intervention (n = 4). There was no PA rebleeding or reintervention for any patient after discharge over the reported follow-up periods. Three patients died during the trauma hospitalization for reasons unrelated to the PAs. CONCLUSIONS: Endovascular treatment of traumatic visceral and extremity PAs is efficacious with minimal complication rates and low reintervention requirements.

Electroencephalography Measures are Useful for Identifying Large Acute Ischemic Stroke in the Emergency Department.

BACKGROUND: Early diagnosis of stroke optimizes reperfusion therapies, but behavioral measures have incomplete accuracy. Electroencephalogram (EEG) has high sensitivity for immediately detecting brain ischemia. This pilot study aimed to evaluate feasibility and utility of EEG for identifying patients with a large acute ischemic stroke during Emergency Department (ED) evaluation, as these data might be useful in the prehospital setting. METHODS: A 3-minute resting EEG was recorded using a dense-array (256-lead) system in patients with suspected acute stroke arriving at the ED of a US Comprehensive Stroke Center. RESULTS: An EEG was recorded in 24 subjects, 14 with acute cerebral ischemia (including 5 with large acute ischemic stroke) and 10 without acute cerebral ischemia. Median time from stroke onset to EEG was 6.6 hours; and from ED arrival to EEG, 1.9 hours. Delta band power (P = .004) and the alpha/delta frequency band ratio (P = .0006) each significantly distinguished patients with large acute ischemic stroke (n = 5) from all other patients with suspected stroke (n = 19), with the best diagnostic utility coming from contralesional hemisphere signals. Larger infarct volume correlated with higher EEG power in the alpha/delta frequency band ratio within both the ipsilesional (r = -0.64, P = .013) and the contralesional (r = -0.78, P = .001) hemispheres. CONCLUSIONS: Within hours of stroke onset, EEG measures (1) identify patients with large acute ischemic stroke and (2) correlate with infarct volume. These results suggest that EEG measures of brain function may be useful to improve diagnosis of large acute ischemic stroke in the ED, findings that might be useful to pre-hospital applications.

Role of Interventional Radiology in Complications of Portal Hypertension.

Portal hypertension, a consequence of end-stage liver disease and liver cirrhosis can lead to significant morbidity and mortality for patients through abnormal fluid accumulation as well as the formation of portosystemic shunts and varices. Treatment of the sequelae of portal hypertension can be achieved through endovascular management by referral to an interventional radiologist on an outpatient or emergent basis as required. Current techniques include the placement of peritoneovenous shunts and tunneled peritoneal drains, the creation of transjugular intrahepatic portosystemic shunts, or the obliteration of shunts via balloon-occluded retrograde transvenous obliteration (BRTO). In addition, newer procedural techniques utilizing vascular plugs and coils have reduced risks of the traditional BRTO procedure. Modified-BRTO procedures, known as plug-assisted and coil-assisted retrograde transvenous obliteration (PARTO and CARTO, respectively) have become the standard of care at many institutions for the treatment of gastric varices and portosystemic shunt-induced hepatic encephalopathy. This review examines the most recent literature of the management of portal hypertension by interventional radiologists, evaluating treatment options as well as the clinical and technical outcomes of TIPS, peritoneovenous shunts, tunneled peritoneal drains, BRTOs, and modified-BRTOs as well as future directions in the development of procedural techniques.

Sixty-hertz stimulation improves bradykinesia and amplifies subthalamic low-frequency oscillations.

BACKGROUND: The objective of this study was to investigate the hypothesis that attenuation of subthalamic nucleus (STN) alpha-/beta-band oscillations is causal to improvement in bradykinesia. METHODS: STN local field potentials from a sensing neurostimulator (Activa® PC+S; Medtronic, Inc.) and kinematics from wearable sensors were recorded simultaneously during 60- and 140-Hz deep brain stimulation (DBS) in 9 freely moving PD subjects (15 STNs) performing repetitive wrist flexion-extension. Kinematics were recorded during 20-Hz DBS in a subgroup. RESULTS: Both 60- and 140-Hz DBS improved the angular velocity and frequency of movement (P = 0.002 and P = 0.029, respectively, for 60 Hz; P < 0.001 and P < 0.001, respectively, for 140 Hz), but 60-Hz DBS did not attenuate beta-band power (13-30 Hz). In fact, 60-Hz DBS amplified alpha/low-beta (11-15 Hz, P = 0.007) and attenuated high-beta power (19-27 Hz, P < 0.001), whereas 140-Hz DBS broadly attenuated beta power (15-30 Hz, P < 0.001). Only 60-Hz DBS improved the regularity of angular range (P = 0.046) and 20-Hz DBS did not worsen bradykinesia. There was no correlation between beta-power modulation and bradykinesia. CONCLUSIONS: These novel results obtained from freely moving PD subjects demonstrated that both 140- and 60-Hz DBS improved bradykinesia and attenuated high beta oscillations; however, 60-Hz DBS amplified a subband of alpha/low-beta oscillations, and DBS at a beta-band frequency did not worsen bradykinesia. Based on recent literature, we suggest that both 140- and 60-Hz DBS decouple the cortico-STN hyperdirect pathway, whereas 60-Hz DBS increases coupling within striato-STN circuitry. These results inform future algorithms for closed-loop DBS in PD. © 2016 International Parkinson and Movement Disorder Society.

Subthalamic oscillations and phase amplitude coupling are greater in the more affected hemisphere in Parkinson's disease.

OBJECTIVE: Determine the incidence of resting state oscillations in alpha/beta, high frequency (HFO) bands, and their phase amplitude coupling (PAC) in a large cohort in Parkinson's disease (PD). METHODS: Intra-operative local field potentials (LFPs) from subthalamic nucleus (STN) were recorded from 100 PD subjects, data from 74 subjects were included in the analysis. RESULTS: Alpha/beta oscillations were evident in >99%, HFO in 87% and PAC in 98% of cases. Alpha/beta oscillations (P<0.01) and PAC were stronger in the more affected (MA) hemisphere (P=0.03). Alpha/beta oscillations were primarily found in 13-20Hz (low beta). Beta and HFO frequencies with the greatest coupling, were positively correlated (P=0.001). Tremor attenuated alpha (P=0.002) and beta band oscillations (P<0.001). CONCLUSIONS: STN alpha/beta band oscillations and PAC were evident in ⩾98% cases and were greater in MA hemisphere. Resting tremor attenuated underlying alpha/beta band oscillations. SIGNIFICANCE: Beta band LFP power may be used to drive adaptive deep brain stimulation (aDBS), augmented by a kinematic classifier in tremor dominant PD.

Auditory cueing in Parkinson's patients with freezing of gait. What matters most: Action-relevance or cue-continuity?

Gait disturbances are a common feature of Parkinson's disease, one of the most severe being freezing of gait. Sensory cueing is a common method used to facilitate stepping in people with Parkinson's. Recent work has shown that, compared to walking to a metronome, Parkinson's patients without freezing of gait (nFOG) showed reduced gait variability when imitating recorded sounds of footsteps made on gravel. However, it is not known if these benefits are realised through the continuity of the acoustic information or the action-relevance. Furthermore, no study has examined if these benefits extend to PD with freezing of gait. We prepared four different auditory cues (varying in action-relevance and acoustic continuity) and asked 19 Parkinson's patients (10 nFOG, 9 with freezing of gait (FOG)) to step in place to each cue. Results showed a superiority of action-relevant cues (regardless of cue-continuity) for inducing reductions in Step coefficient of variation (CV). Acoustic continuity was associated with a significant reduction in Swing CV. Neither cue-continuity nor action-relevance was independently sufficient to increase the time spent stepping before freezing. However, combining both attributes in the same cue did yield significant improvements. This study demonstrates the potential of using action-sounds as sensory cues for Parkinson's patients with freezing of gait. We suggest that the improvements shown might be considered audio-motor 'priming' (i.e., listening to the sounds of footsteps will engage sensorimotor circuitry relevant to the production of that same action, thus effectively bypassing the defective basal ganglia).

Beta oscillations in freely moving Parkinson's subjects are attenuated during deep brain stimulation.

BACKGROUND: Investigations into the effect of deep brain stimulation (DBS) on subthalamic (STN) beta (13-30 Hz) oscillations have been performed in the perioperative period with the subject tethered to equipment. Using an embedded sensing neurostimulator, this study investigated whether beta power was similar in different resting postures and during forward walking in freely moving subjects with Parkinson's disease (PD) and whether STN DBS attenuated beta power in a voltage-dependent manner. METHODS: Subthalamic local field potentials were recorded from the DBS lead, using a sensing neurostimulator (Activa(®) PC+S, Medtronic, Inc., Food and Drug Administration- Investigational Device Exemption (IDE)-, institutional review board-approved) from 15 PD subjects (30 STNs) off medication during lying, sitting, and standing, during forward walking, and during randomized periods of 140 Hz DBS at 0 V, 1 V, and 2.5/3 V. Continuous video, limb angular velocity, and forearm electromyography recordings were synchronized with neural recordings. Data were parsed to avoid any movement or electrical artifact during resting states. RESULTS: Beta power was similar during lying, sitting, and standing (P = 0.077, n = 28) and during forward walking compared with the averaged resting state (P = 0.466, n = 24), although akinetic rigid PD subjects tended to exhibit decreased beta power when walking. Deep brain stimulation at 3 V and at 1 V attenuated beta power compared with 0 V (P < 0.003, n = 14), and this was voltage dependent (P < 0.001). CONCLUSIONS: Beta power was conserved during resting and forward walking states and was attenuated in a voltage-dependent manner during 140-Hz DBS. Phenotype may be an important consideration if this is used for closed-loop DBS.

Sixty hertz neurostimulation amplifies subthalamic neural synchrony in Parkinson's disease.

High frequency subthalamic nucleus (STN) deep brain stimulation (DBS) improves the cardinal motor signs of Parkinson's disease (PD) and attenuates STN alpha/beta band neural synchrony in a voltage-dependent manner. While there is a growing interest in the behavioral effects of lower frequency (60 Hz) DBS, little is known about its effect on STN neural synchrony. Here we demonstrate for the first time that during intra-operative 60 Hz STN DBS, one or more bands of resting state neural synchrony were amplified in the STN in PD. We recorded intra-operative STN resting state local field potentials (LFPs) from twenty-eight STNs in seventeen PD subjects after placement of the DBS lead (model 3389, Medtronic, Inc.) before and during three randomized neurostimulation sets (130 Hz/1.35V, 130 Hz/2V, 60 Hz/2V). During 130 Hz/2V DBS, baseline (no DBS) STN alpha (8-12 Hz) and beta (13-35 Hz) band power decreased (N=14, P < 0.001 for both), whereas during 60 Hz/2V DBS, alpha band and peak frequency power increased (P = 0.012, P = 0.007, respectively). The effect of 60 Hz/2V DBS opposed that of power-equivalent (130 Hz/1.35V) DBS (alpha: P < 0.001, beta: P = 0.006). These results show that intra-operative 60 Hz STN DBS amplified whereas 130 Hz STN DBS attenuated resting state neural synchrony in PD; the effects were frequency-specific. We demonstrate that neurostimulation may be useful as a tool to selectively modulate resting state resonant bands of neural synchrony and to investigate its influence on motor and non-motor behaviors in PD and other neuropsychiatric diseases.

Arrhythmokinesis is evident during unimanual not bimanual finger tapping in Parkinson's disease.

BACKGROUND: Arrhythmokinesis, the variability in repetitive movements, is a fundamental feature of Parkinson's disease (PD). We hypothesized that unimanual repetitive alternating finger tapping (AFT) would reveal more arrhythmokinesis compared to bimanual single finger alternating hand tapping (SFT), in PD. METHODS: The variability of inter-strike interval (CVISI) and of amplitude (CVAMP) during AFT and SFT were measured on an engineered, MRI-compatible keyboard in sixteen PD subjects off medication and in twenty-four age-matched controls. RESULTS: The CVISI and CVAMP of the more affected (MA) and less affected (LA) sides in PD subjects were greater during AFT than SFT (P < 0.05). However, there was no difference between AFT and SFT for controls. Both CVISI and CVAMP were greater in the MA and LA hands of PD subjects versus controls during AFT (P < 0.01). The CVISI and CVAMP of the MA, but not the LA hand, were greater in PDs versus controls during SFT (P < 0.05). Also, AFT, but not SFT, detected a difference between the MA and LA hands of PDs (P < 0.01). CONCLUSIONS: Unimanual, repetitive alternating finger tapping brings out more arrhythmokinesis compared to bimanual, single finger tapping in PDs but not in controls. Arrhythmokinesis during unimanual, alternating finger tapping captured a significant difference between both the MA and LA hands of PD subjects and controls, whereas that during a bimanual, single finger tapping task only distinguished between the MA hand and controls. Arrhythmokinesis underlies freezing of gait and may also underlie the freezing behavior documented in fine motor control if studied using a unimanual alternating finger tapping task.

Somatosensory projections to cochlear nucleus are upregulated after unilateral deafness.

The cochlear nucleus (CN) receives innervation from auditory and somatosensory structures, which can be identified using vesicular glutamate transporters, VGLUT1 and VGLUT2. VGLUT1 is highly expressed in the magnocellular ventral CN (VCN), which receives auditory nerve inputs. VGLUT2 is predominantly expressed in the granule cell domain (GCD), which receives nonauditory inputs from somatosensory nuclei, including spinal trigeminal nucleus (Sp5) and cuneate nucleus (Cu). Two weeks after unilateral deafening VGLUT1 is significantly decreased in ipsilateral VCN while VGLUT2 is significantly increased in the ipsilateral GCD (Zeng et al., 2009), putatively reflecting decreased inputs from auditory nerve and increased inputs from nonauditory structures in guinea pigs. Here, we wished to determine whether the upregulation of VGLUT2 represents increases in the number of somatosensory projections to the CN that are maintained for longer periods of time. Thus, we examined concurrent changes in VGLUT levels and somatosensory projections in the CN using immunohistochemistry combined with anterograde tract tracing three and six weeks following unilateral deafening. The data reveal that unilateral deafness leads to increased numbers of VGLUT2-colabeled Sp5 and Cu projections to the ventral and dorsal CN. These findings suggest that Sp5 and Cu play significant and unique roles in cross-modal compensation and that, unlike after shorter term deafness, neurons in the magnocellular regions also participate in the compensation. The enhanced glutamatergic somatosensory projections to the CN may play a role in neural spontaneous hyperactivity associated with tinnitus.