Welcome to Hirsla, Landspítali University Hospital research archive

Hirsla is an open access repository, designed as a place to store, index, preserve and redistribute in digital format scholarly work of Landspitali employees. (A/H1N1)

  • Comparison of Spasticity in Spinal Cord Injury and Stroke Patients Using Reflex Period in Pendulum Test.

    Kristinsdottir, Kristjana; Magnusdottir, Gigja; Chenery, Belinda; Gudmundsdottir, Vilborg; Gudfinnsdottir, Halla Kristin; Karason, Halldor; Ludvigsdottir, Gudbjorg K; Helgason, Thordur; 1Health Technology Center, Reykjavik University - Landspitali-University Hospital, Reykjavik, Iceland. 2Rehabilitation Department at Grensas, Landspitali-University Hospital, Reykjavík, Iceland. (PAGEPRESS PUBL, 2020-04-01)
    Spasticity is a motor impairment present in patients with both stroke and spinal cord injury. In this research, the results from the Wartenberg pendulum test, performed on stroke and spinal cord injury patients using goniometers and electromyogram recordings of the quadriceps, were reviewed and a new parameter to quantify spasticity was extracted. The Reflex Period (RP) of the pendulum test was defined as the time span from 50% of the maximum velocity of the leg swing to the activation of muscle contraction in the quadriceps, determined from the EMG. The results suggest that the reflex period in stroke patients is generally shorter than in those suffering from spinal cord injury. Keywords: Spasticity; Spinal Cord Injury; Stroke; Wartenberg pendulum test.
  • Using high density EEG to assess TMS treatment in patients with schizophrenia.

    Marcu, Sara; Pegolo, Elena; Ívarsson, Eysteinn; Jónasson, Aron D; Jónasson, Viktor D; Aubonnet, Romain; Gargiulo, Paolo; Banea, Ovidiu C; 1Reykjavik University, School of Science and Engineering, Biomedical Engineering, Reykjavik, Iceland. 2Department of Information Engineering, University of Padova, Italy. 3Clinical Neurophysiology Unit, Neurology Department, National University Hospital of Iceland. 4Psychiatric Department, National University Hospital of Iceland. (PAGEPRESS PUBL, 2020-04-01)
    We present preliminary results from the ongoing study entitled "Icelandic AVH-TMS" which aim is to study the effectiveness of repetitive transcranial magnetic stimulation (rTMS) treatment for patients with schizophrenia and with persistent auditory verbal hallucinations (AVH) using symptoms and psychometric scales and high-density EEG system (256 channels). The aim of the present work was to describe cortical topography of the auditory evoked responses like P50 and N100-P300 complex in healthy participants and patients with schizophrenia and to define a robust methodology of signal quantification using dense-array EEG. Preliminary data is shown for three healthy participants and three patients in baseline conditions and for two patients we show the results recorded before and after 10 days rTMS treatment. Our results show differences in sensory gating (P50 suppresion) and a stronger N100-P300 response to rare audio stimulus after the treatment. Moreover we show the value of assessing brain electrical activity from high-density EEG (256 channels) analyzing the results in different regions of interest. However, it is premature and hazardous to assume that rTMS treatment effectiveness in patients with AVH can be assessed using P50 suppression ratio. Keywords: P300; P50; Transcranial magnetic stimulation; high density EEG; schizophrenia.
  • Machine learning predictive system based upon radiodensitometric distributions from mid-thigh CT images.

    Recenti, Marco; Ricciardi, Carlo; Edmunds, Kyle; Gislason, Magnus K; Gargiulo, Paolo; 1Institute for Biomedical and Neural Engineering, Reykjavík University, Reykjavík, Iceland. 2Department of Advanced Biomedical Sciences, University Hospital of Naples 'Federico II', Naples, Italy. 3Department of Science, Landspítali, Reykjavík, Iceland. (PAGEPRESS PUBL, 2020-04-01)
    The nonlinear trimodal regression analysis (NTRA) method based on radiodensitometric CT images distributions was developed for the quantitative characterization of soft tissue changes according to the lower extremity function of elderly subjects. In this regard, the NTRA method defines 11 subject-specific soft tissue parameters and has illustrated high sensitivity to changes in skeletal muscle form and function. The present work further explores the use of these 11 NTRA parameters in the construction of a machine learning (ML) system to predict body mass index and isometric leg strength using tree-based regression algorithms. Results obtained from these models demonstrate that when using an ML approach, these soft tissue features have a significant predictive value for these physiological parameters. These results further support the use of NTRA-based ML predictive assessment and support the future investigation of other physiological parameters and comorbidities. Keywords: Computed Tomography; Machine learning; body mass index; isometric leg strength; soft tissue.
  • Peripheral Nervous System Disease in Systemic Lupus Erythematosus: Results From an International Inception Cohort Study

    Hanly, John G.; Li, Qiuju; Su, Li; Urowitz, Murray B.; Gordon, Caroline; Bae, Sang Cheol; Romero-Diaz, Juanita; Sanchez-Guerrero, Jorge; Bernatsky, Sasha; Clarke, Ann E.; et al. (Wiley, 2020-01-01)
    Objective: To determine the frequency, clinical characteristics, associations, and outcomes of different types of peripheral nervous system (PNS) disease in a multiethnic/multiracial, prospective inception cohort of systemic lupus erythematosus (SLE) patients. Methods: Patients were evaluated annually for 19 neuropsychiatric (NP) events including 7 types of PNS disease. SLE disease activity, organ damage, autoantibodies, and patient and physician assessment of outcome were measured. Time to event and linear regressions were used as appropriate. Results: Of 1,827 SLE patients, 88.8% were female, and 48.8% were white. The mean ± SD age was 35.1 ± 13.3 years, disease duration at enrollment was 5.6 ± 4.2 months, and follow-up was 7.6 ± 4.6 years. There were 161 PNS events in 139 (7.6%) of 1,827 patients. The predominant events were peripheral neuropathy (66 of 161 [41.0%]), mononeuropathy (44 of 161 [27.3%]), and cranial neuropathy (39 of 161 [24.2%]), and the majority were attributed to SLE. Multivariate Cox regressions suggested longer time to resolution in patients with a history of neuropathy, older age at SLE diagnosis, higher SLE Disease Activity Index 2000 scores, and for peripheral neuropathy versus other neuropathies. Neuropathy was associated with significantly lower Short Form 36 (SF-36) physical and mental component summary scores versus no NP events. According to physician assessment, the majority of neuropathies resolved or improved over time, which was associated with improvements in SF-36 summary scores for peripheral neuropathy and mononeuropathy. Conclusion: PNS disease is an important component of total NPSLE and has a significant negative impact on health-related quality of life. The outcome is favorable for most patients, but our findings indicate that several factors are associated with longer time to resolution.
  • Associations of physical activity with vitamin D status depends on obesity status in old adults.

    OG, Geirsdottir; M, Chang; Pv, Jonsson; I, Thorsdottir; A, Ramel; 1The Icelandic Gerontological Research Center, Reykjavik, Iceland; Faculty of Food Science and Nutrition, University of Iceland, Reykjavik, Iceland. 2The Icelandic Gerontological Research Center, Reykjavik, Iceland; Sport Science, School of Science and Engineering, Reykjavik University, Reykjavik, Iceland. 3The Icelandic Gerontological Research Center, Reykjavik, Iceland; Department of Geriatrics, National University Hospital of Iceland, Reykjavik, Iceland. 4School of Health Sciences, University of Iceland, Reykjavik, Iceland. 5The Icelandic Gerontological Research Center, Reykjavik, Iceland; Faculty of Food Science and Nutrition, University of Iceland, Reykjavik, Iceland. Electronic address: alfonsra@hi.is. (Elsevier, 2020-07-12)
    Purpose: Obesity has been associated with low 25-hydroxy-vitamin D (25OHD). The causes of hypovitaminosis D in obese individuals are not known. The present work aimed to investigate 25OHD in obese and normal-/overweight subjects with consideration of leisure-time physical activity (LTPA). Methods: Community-dwelling old adults (N = 229, 73.7 ± 5.7yrs, 58.2% female) from the Reykjavik capital area in Iceland participated in this cross-sectional study. LTPA, vitamin D intake, body composition and background variables were assessed. 25OHD was measured in fasting blood samples. Results: Mean LTPA was 5.7 ± 5.6 h/week and the common activities were walking and gardening. Mean 25OHD was 66.7 ± 28.1 nmol/L and 8.5/21.2% were below 30 and 50 nmol/L, respectively. Obese participants (n = 84) had lower 25OHD (-11.0 ± 3.8 nmol/L,P < 0.001) and lower LTPA (-2.5 + 0.8 h/week,P = 0.001) than normal-/overweight subjects (n = 145). Linear models showed that LTPA (h/week) was associated with higher 25OHD in normal-/overweight participants only (1.3 nmol/L, P < 0.001) but not in obese (-0.7 nmol, P = 0.245). Fish oil intake was associated with higher 25OHD both in normal-/overweight (19.2 ± 4.5 nmol/L, P = 0.001) and obese subjects (13.4 ± 5.3 nmol/L, P = 0.013). Conclusions: Obese community-dwelling old adults in Iceland have lower 25OHD than their normal-/overweight counterparts. LTPA was associated with a higher 25OHD in normal-/overweight, but not in obese participants. However, fish oil was associated with higher 25OHD independently from obesity status. Thus, vitamin D supplementation is important for obese old adults to maintain vitamin D levels. Keywords: Aging; Fish oil; Leisure-time physical activity; Obesity; Vitamin D.

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