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Articles by K. L Leenders
Total Records ( 2 ) for K. L Leenders
  A. M Meppelink , B. M de Jong , R Renken , K. L Leenders , F. W Cornelissen and T. van Laar
 

Impaired visual processing may play a role in the pathophysiology of visual hallucinations in Parkinson's disease. In order to study involved neuronal circuitry, we assessed cerebral activation patterns both before and during recognition of gradually revealed images in Parkinson's disease patients with visual hallucinations (PDwithVHs), Parkinson's disease patients without visual hallucinations (PDnonVHs) and healthy controls. We hypothesized that, before image recognition, PDwithVHs would show reduced bottom-up visual activation in occipital-temporal areas and increased (pre)frontal activation, reflecting increased top-down demand. Overshoot of the latter has been proposed to play a role in generating visual hallucinations. Nine non-demented PDwithVHs, 14 PDnonVHs and 13 healthy controls were scanned on a 3 Tesla magnetic resonance imaging scanner. Static images of animals and objects gradually appearing out of random visual noise were used in an event-related design paradigm. Analyses were time-locked on the moment of image recognition, indicated by the subjects’ button-press. Subjects were asked to press an additional button on a colour-changing fixation dot, to keep attention and motor action constant and to assess reaction times. Data pre-processing and statistical analysis were performed with statistical parametric mapping-5 software. Bilateral activation of the fusiform and lingual gyri was seen during image recognition in all groups (P < 0.001). Several seconds before image recognition, PDwithVHs showed reduced activation of the lateral occipital cortex, compared with both PDnonVHs and healthy controls. In addition, reduced activation of extrastriate temporal visual cortices was seen just before image recognition in PDwithVHs. The association between increased vulnerability for visual hallucintions in Parkinson's disease and impaired visual object processing in occipital and temporal extrastriate visual cortices supported the hypothesis of impaired bottom-up visual processing in PDwithVHs. Support for the hypothesized increased top-down frontal activation was not obtained. The finding of activation reductions in ventral/lateral visual association cortices in PDwithVHs before image recognition further helps to explain functional mechanisms underlying visual hallucinations in Parkinson's disease.

  L Timmermann , K. A. M Pauls , K Wieland , R Jech , G Kurlemann , N Sharma , S. S Gill , C. A Haenggeli , S. J Hayflick , P Hogarth , K. L Leenders , P Limousin , C. J Malanga , E Moro , J. L Ostrem , F. J Revilla , P Santens , A Schnitzler , S Tisch , F Valldeoriola , J Vesper , J Volkmann , Woitalla and S. Peker
 

Neurodegeneration with brain iron accumulation encompasses a heterogeneous group of rare neurodegenerative disorders that are characterized by iron accumulation in the brain. Severe generalized dystonia is frequently a prominent symptom and can be very disabling, causing gait impairment, difficulty with speech and swallowing, pain and respiratory distress. Several case reports and one case series have been published concerning therapeutic outcome of pallidal deep brain stimulation in dystonia caused by neurodegeneration with brain iron degeneration, reporting mostly favourable outcomes. However, with case studies, there may be a reporting bias towards favourable outcome. Thus, we undertook this multi-centre retrospective study to gather worldwide experiences with bilateral pallidal deep brain stimulation in patients with neurodegeneration with brain iron accumulation. A total of 16 centres contributed 23 patients with confirmed neurodegeneration with brain iron accumulation and bilateral pallidal deep brain stimulation. Patient details including gender, age at onset, age at operation, genetic status, magnetic resonance imaging status, history and clinical findings were requested. Data on severity of dystonia (Burke Fahn Marsden Dystonia Rating Scale—Motor Scale, Barry Albright Dystonia Scale), disability (Burke Fahn Marsden Dystonia Rating Scale—Disability Scale), quality of life (subjective global rating from 1 to 10 obtained retrospectively from patient and caregiver) as well as data on supportive therapy, concurrent pharmacotherapy, stimulation settings, adverse events and side effects were collected. Data were collected once preoperatively and at 2–6 and 9–15 months postoperatively. The primary outcome measure was change in severity of dystonia. The mean improvement in severity of dystonia was 28.5% at 2–6 months and 25.7% at 9–15 months. At 9–15 months postoperatively, 66.7% of patients showed an improvement of 20% or more in severity of dystonia, and 31.3% showed an improvement of 20% or more in disability. Global quality of life ratings showed a median improvement of 83.3% at 9–15 months. Severity of dystonia preoperatively and disease duration predicted improvement in severity of dystonia at 2–6 months; this failed to reach significance at 9–15 months. The study confirms that dystonia in neurodegeneration with brain iron accumulation improves with bilateral pallidal deep brain stimulation, although this improvement is not as great as the benefit reported in patients with primary generalized dystonias or some other secondary dystonias. The patients with more severe dystonia seem to benefit more. A well-controlled, multi-centre prospective study is necessary to enable evidence-based therapeutic decisions and better predict therapeutic outcomes.

 
 
 
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