Willem J R van Ouwerkerk

VU University Amsterdam, Amsterdamo, North Holland, Netherlands

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Publications (41)62.06 Total impact

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    Full-text · Dataset · Dec 2015
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    Full-text · Dataset · Dec 2015
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    ABSTRACT: An accessory to suprascapular nerve (XIN-SSN) transfer is considered in patients with obstetric brachial plexus lesion who fail to recover active shoulder external rotation. The aim of this study was to evaluate the quality of extraplexal suprascapular nerve neurotization and to perform a detailed analysis of the infraspinatus muscle (IM) and shoulder external rotation. A XIN-SSN transfer was performed in 14 patients between 2000 and 2007. Patients had been operated at the age of 3.7 ± 2.8 years. Follow-up examinations were conducted up to 8.5 ± 2.5 years. Magnetic resonance imaging was performed to investigate muscle trophism. Fatty muscle degeneration of the IM was classified according to the Goutallier classification. We conducted nerve conduction velocity studies of the suprascapular nerve and needle electromyography of the IM to assess pathologic spontaneous activity and interference patterns. Active glenohumeral shoulder external rotation and global shoulder function were evaluated using the Mallet score. Postoperatively, growth of the IM increased equally on the affected and unaffected sides, although significant differences of muscle thickness persisted over time. There was only grade 1 or 2 fatty degeneration pre- and postoperatively. Electromyography of the IM revealed a full interference pattern in all except one patient, and there was no pathological spontaneous activity. Glenohumeral external rotation as well as global shoulder function increased significantly. Our results indicate that the anastomosis after XIN-SSN transfer is functional and that successful reinnervation of the infraspinatus muscle may enable true glenohumeral active external rotation.
    No preview · Article · Jun 2015 · Child s Nervous System
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    Full-text · Dataset · May 2013
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    ABSTRACT: Aim: Denervation after obstetric brachial plexus lesion (OBPL) is associated with reduced musculoskeletal growth in the upper arm. The aim of this study was to investigate whether reduced growth of upper arm flexor and extensor muscles is related to active elbow function and humeral length. Method: In this study, 31 infants age less than 6 months (mean age 4.3mo; range 2.1-5.9mo; 17 males; 14 females;) with unilateral OBPL (Narakas class I, 19; II, 3; III, 2; and IV, 7) treated at the VU medical centre, in whom neurosurgical reconstruction was considered were prospectively studied using magnetic resonance imaging of both arms at a mean age of 4.3 months. Humeral length and the cross-sectional area (CSA) of elbow flexor and extensor muscles were measured in both upper arms. Paresis of elbow function was estimated when the infants were a mean age of 4.5 months using the Gilbert score. Results: Both flexor and extensor CSAs were significantly smaller on the affected side than on the unaffected side (88% [SD 32%], p=0.020, and 88% [SD 24%], p=0.001 respectively), as was humeral length (96% [SD 7%], p=0.005) (unaffected side 100% in all cases). There was no relation between the reduction in flexor and extensor CSA and residual muscle function. In 17 out of 31 patients, hypertrophy of flexor and/or extensor muscles was observed. Humeral length was not related to muscle parameters. Interpretation: Denervation has different effects on muscle growth and function as well as bone growth. In young infants with an OBPL, muscle size is not a predictor of muscle function. Flexion contractures of the elbow later in childhood may not be explained by a dominance of flexor muscle mass in infants.
    Full-text · Article · Jul 2012 · Developmental Medicine & Child Neurology
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    ABSTRACT: The purpose of this study was to review the epidemiology and the clinical, radiological, pathological, and follow-up data of all surgically treated pediatric meningiomas during the last 35 years in The Netherlands. Patients were identified in the Pathological and Anatomical Nationwide Computerized Archive database, the nationwide network and registry of histopathology and cytopathology in The Netherlands. Pediatric patients of 18 years or younger at first operation in 1974-2009 with the diagnosis meningioma were included. Clinical records, follow-up data, radiological findings, operative reports, and pathological examinations were reviewed. In total, 72 patients (39 boys) were identified. The incidence of operated meningiomas in the Dutch pediatric population is 1:1,767,715 children per year. Median age at diagnosis was 13 years (range 0-18 years). Raised intracranial pressure and seizures were the most frequent signs at presentation. Thirteen (18 %) patients had neurofibromatosis type 2 (NF2). Fifty-three (74 %) patients had a meningioma World Health Organization grade I. Total resection was achieved in 35 of 64 patients. Fifteen patients received radiotherapy postoperatively. Mean follow-up was 4.8 years (range 0-27.8 years). Three patients died as a direct result of their meningioma within 3 years. Four patients with NF2 died as a result of multiple tumors. Nineteen patients had disease progression, requiring additional treatment. Meningiomas are extremely rare in the pediatric population; 25 % of all described meningiomas show biological aggressive behavior in terms of disease progression, requiring additional treatment. The 5-year survival is 83.9 %, suggesting that the biological behavior of pediatric menigiomas is more aggressive than that of its adult counterparts.
    Full-text · Article · Apr 2012 · Child s Nervous System
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    ABSTRACT: Intrathecal baclofen (ITB) treatment is frequently used for individuals with severe, but non-progressive, spasticity refractory to oral treatment. However, experiences with ITB in patients with progressive neurological disorders of childhood causing spasticity are limited. To investigate whether ITB is an option in patients with progressive neurological disorders causing spasticity in childhood. A systematic literature search in Embase, Pubmed and the Cochrane Library was performed. We identified six eligible studies considering patients with progressive neurological disease in childhood and receiving ITB treatment. The studies included a total of seven paediatric patients and four adult patients. Improvement was reported in spasticity, spasms, pain, gait, activities of daily life and providing care. High satisfaction is described. ITB has beneficial effects in paediatric patients with progressive neurological disease. However, the level of evidence is limited due to the small number of available studies and due to the poor quality of these studies.
    No preview · Article · Oct 2011 · European journal of paediatric neurology: EJPN: official journal of the European Paediatric Neurology Society
  • Els Spaargaren · Jasmyn Ahmed · Willem J.R. van Ouwerkerk · Vincent de Groot · Heleen Beckerman
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    ABSTRACT: Children with an obstetric brachial plexus injury (OBPI) can experience problems in the performance of meaningful activities such as writing, bimanual activities, and participation in sports and leisure activities. To quantify the everyday functioning and participation of 7-8 year-old children with an OBPI, with special emphasis on writing, and to investigate associated characteristics. Parents of children with an OBPI were sent a self-report questionnaire regarding the school performance, writing abilities, bimanual hand use, and participation in sports and leisure activities of their child, assessed with the Vineland Adaptive Behavior Scales (VABS sub-scale writing), the ABILHAND-kids, and the Children's Assessment of Participation and Enjoyment (CAPE). Furthermore, questions were asked about socio-demographic variables, medical history, pain, and the use of assistive devices. Fifty three questionnaires were filled in (response 61%). According to the parents, 66% of their children were almost completely recovered, and 58% had a near normal arm function. Most of the children preferred to use their non-involved hand. More than 45% of the children complained about pain, and 39.6% had difficulties with writing, which resulted in a mean developmental delay of 8 months on the VABS sub-scale. Children with writing problems significantly more often had neurosurgery, were living with a single parent, more often received assistance at school, and had a significantly lower ABILHAND-kids score, compared to children with no writing problems. Large percentages of 7-8 year-old children with an OBPI experience difficulties with writing and have musculoskeletal pain. Restrictions in participation were less pronounced.
    No preview · Article · Jul 2011 · European journal of paediatric neurology: EJPN: official journal of the European Paediatric Neurology Society
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    ABSTRACT: Treatment options for dystonic cerebral palsy (CP) are limited. Our aims were to determine whether intrathecal baclofen (ITB) improves daily care, decreases dystonia and decreases pain in patients with dystonic CP. Patients received randomized blinded treatment with ITB or placebo. Scores on problems of daily care were recorded and dystonia, pain and comfort were assessed. Four patients (three males, average age 12 years 6 months) were included (all Gross Motor Function Classification System level V). During the trial period problem scores and dystonia scores decreased in all four patients. In this pilot study we report positive functional effects of ITB trial treatment in four patients with dystonic CP. A randomized trial with a larger cohort is needed to verify these results.
    No preview · Article · May 2011 · European journal of paediatric neurology: EJPN: official journal of the European Paediatric Neurology Society
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    ABSTRACT: The primary aim of this prospective cohort study was to evaluate the short-term (1 year) and long-term (mean 6 years) effects of selective dorsal rhizotomy (SDR) on gross motor function and spasticity in ambulatory children with spastic diplegia. Secondary aims were to investigate side effects, additional treatment during follow-up (botulinum toxin type A injections or orthopedic surgery), and parental satisfaction. Thirty-three children who had undergone SDR at a mean age of 6 years and 7 months (± 2 years) were included. There were 7 children at Gross Motor Function Classification System (GMFCS) Level I, 7 at Level II, and 19 at Level III. Gross motor function was assessed with the Gross Motor Function Measure-66 (GMFM-66). Spasticity was measured according to a modified Tardieu scale. Side effects, additional treatment, and parental satisfaction were recorded using a parental questionnaire and medical records. At 1-year follow-up, mean GMFM-66 scores improved significantly by 4.3 ± 4.1 points. Children at GMFCS Levels I and II showed significantly more improvement (7.2 points) on the GMFM-66 compared with children at GMFCS Level III (2.9 points). On long-term follow-up (mean 6 years ± 22 months), mean GMFM-66 scores improved significantly by 6.5 ± 5.9 points, without a difference between children at GMFCS Levels I and II and Level III. No relapse of spasticity was noted. Ten children (30%) needed orthopedic surgery and 13 children (39%) received botulinum toxin type A treatment after SDR. Twenty (91%) of the 22 parents who answered the questionnaire at long-term follow-up believed that their child's functioning had improved after SDR. Selective dorsal rhizotomy resulted in short- and long-term improvements in gross motor function, without relapse of spasticity. However, the majority of the children still needed additional surgery or botulinum toxin A treatment.
    Full-text · Article · May 2011 · Journal of Neurosurgery Pediatrics
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    ABSTRACT: Shoulder deformities in children with a birth brachial plexus injury (BBPI) are caused by muscle imbalances; however, the underlying mechanisms are unclear. The aim of this study was to assess the early interactions between shoulder muscles and shoulder joint development. In a retrospective magnetic resonance imaging (MRI) study of 36 infants (21 males, 15 females) younger than 12 months (mean 4.8 mo) with unilateral BBPI, volumes and thicknesses of standardized segments of the infraspinatus, subscapularis, and deltoid muscles were measured in both shoulders and expressed as ratios of pathological/unaffected side. The relation between muscle ratios and humeral head subluxation, passive external rotation, glenoid version, and deformity was analysed. Compared with the unaffected side, the muscles of the affected side were of significantly smaller volume and thickness. The subscapularis was the most severely affected muscle, its volume being only 64% (SD 21%) and its thickness only 79% (SD 23%) of the corresponding values on the unaffected side (p < 0.001). Severe subluxation was predicted by the combination of low infraspinatus and subscapularis volume ratios (r(2) = 0.223; p = 0.014), but not by muscle thickness ratios. Subluxation was related to passive external rotation (p < 0.05), glenoid version (p < 0.01), and deformity (p < 0.01). In infants with BBPI, muscle size is decreased during in the first months of life by both atrophy and, possibly, by a reduction in the number of sarcomeres in series. These effects are strongly related to shoulder joint subluxation.
    Full-text · Article · Feb 2011 · Developmental Medicine & Child Neurology
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    F W Neervoort · W J R Van Ouwerkerk · H Folkersma · G J L Kaspers · W P Vandertop
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    ABSTRACT: The primary aim of this study is to perform an internal quality control of pediatric brain tumor surgery in the neurosurgical department of the VU University Medical Center Amsterdam (The Netherlands). Secondly, this study aims to contribute to the accumulating data concerning outcome in pediatric neurosurgery, in order to establish institutional practice benchmarks. We report the surgical mortality and morbidity of 121 patients (0-18 years) surgically treated for a brain tumor from January 1999 to August 2007. Patients, in whom only a brain tumor biopsy was performed, were excluded. Mean age at first surgery was 8.2 years. Of the 121 patients, 14 had a second surgery, and two underwent a third surgery (for a total of 137 operations). Of all 121 primary surgeries, 66% were total resections, 26% subtotal resections, and 8% partial resections. The overall surgical morbidity rate in this study was 69% after first surgery, 50% after second surgery, and one out of two after third surgery. These overall morbidity rates are comparable to other published mixed case series. The surgical mortality rate was 0.8%; this is comparable to the lowest rates reported for high-volume neurosurgical centers. We encourage other neurosurgical centers to collect, analyze, and publish their data. These data can then serve as a basis for comparison with other pediatric neurosurgical centers and will eventually lead to an improvement of pediatric neurosurgical practice and patient care.
    Full-text · Article · Mar 2010 · Child s Nervous System
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    ABSTRACT: To identify MRI characteristics that may predict the functional effect of selective dorsal rhizotomy (SDR) in children with bilateral spastic paresis. We performed SDR in a group of 36 patients. The gross motor functioning measure-66 (GMFM-66) was applied before and after SDR. Available cerebral MRIs were retrospectively classified into three diagnostic groups: periventricular leucomalacia (PVL; n = 10), hydrocephalus (n = 2), and normal (n = 6). In patients with PVL, we scored the severity of the MR abnormalities. We compared the changes in the GMFM-66 after SDR in the diagnostic groups. In patients with PVL, we correlated the severity of the MR abnormalities with the changes in the GMFM-66. The mean follow-up period was 5 years and 4 months (range, 1 year and 1 month to 9 years). The best improvement in gross motor function was observed in patients with normal MRI, and the slightest improvement was observed in patients with hydrocephalus. The severity of the PVL did correlate with the GMFM-66 score before SDR but not with the functional effect of SDR. We conclude that with respect to gross motor skills, the improvements after SDR are good in patients with no MRI abnormalities. In the patients with hydrocephalus, the improvements after SDR were insignificant. In patients with PVL, the improvements were intermediate and did not correlate with the degree of PVL.
    Full-text · Article · Oct 2009 · Child s Nervous System
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    ABSTRACT: Doel van dit onderzoek is een analyse van de complicaties bij kinderen met intrathecale baclofentherapie. Meer specifiek werd gekeken naar aard, frequentie, impact (d.m.v. verzorgertevredenheid) en mogelijke determinanten van het optreden van complicaties. Hiertoe werd retrospectief statusonderzoek uitgevoerd en een cross-sectionele tevredenheidsvragenlijst afgenomen. Alle kinderen (t/m 17 jaar) behandeld met intrathecale baclofentherapie in het VU medisch centrum zijn geanalyseerd. De minimale follow-up was zes maanden. Het betreft baclofenpompimplantaties tussen maart 2001 en mei 2007. Een complicatiefrequentie van 0,28 (0,19-0,42) complicaties per patiënt per jaar werd gevonden. In de literatuur bedraagt de complicatiefrequentie tussen de 0,09 en 0,58 complicaties per patiënt per jaar. Kathetergerelateerde complicaties kwamen het meest frequent voor. Drie gevonden determinanten voor het optreden van complicaties zijn: kathetertiphoogte, pulmonale comorbiditeit en corticosteroïdengebruik. Het tevredenheidsonderzoek wees uit dat ouders/verzorgers van kinderen met één of meer complicaties niet minder tevreden waren dan ouders van kinderen zonder complicaties. Van de ondervraagden zou 88% de keuze voor intrathecale baclofentherapie nog steeds maken. De resultaten van het tevredenheidsonderzoek bevestigen de hypothese dat ouders/verzorgers in hun oordeel de functionele waarde van de behandeling zwaarder laten wegen dan de eventuele complicaties. Aim of this research is an analysis of the complications in children with intrathecal baclofen therapy. More specific by analysing nature, frequency, impact (by means of caregiver satisfaction) and possible determinants of complications. For that purpose retrospective data research was conducted and a cross-sectional satisfaction questionnaire was administered. All children treated with intrathecal baclofen therapy in the VU medical centre, Amsterdam, are included in the study. Minimum follow-up was six months. The baclofen pumps were implanted from March 2001 to May 2007.We found 0.28 (0.19-0.42) complications per patient per year. In other studies this value varies between 0.09 and 0.58 complications per patient per year. Catheter-related complications were the most common. Three determinants proved to be associated with the rate of complications: the level of the catheter tip, pulmonary co-morbidity and the use of corticosteroids. The results of the satisfaction questionnaire showed that there is no less satisfaction in parents/guardians of children with one or more complications as compared to parents of children without complications. Of parents questioned, 88% would again choose for intrathecal baclofen therapy. The results of the satisfaction questionnaire support the hypothesis that in their judgement parents/guardians focus more on functional gain of the treatment than on possible complications.
    No preview · Article · Oct 2009 · Tijdschrift voor kindergeneeskunde
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    R. P. Weenink · W. J. R. van Ouwerkerk
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    ABSTRACT: Samenvatting Een zevenjarig meisje presenteerde zich met torticollis. Voorafgaand had zij een keelinfectie doorgemaakt. CT-scan van de cervicale wervelkolom toonde een atlantoaxiale subluxatie, ook wel het syndroom van Grisel genoemd. Patiente werd behandeld met pijnstillers, spierverslappers en een harde halskraag gedurende een week.
    Full-text · Article · Feb 2009 · Tijdschrift voor kindergeneeskunde
  • Margje Spijker · Rob L M Strijers · Willem J R van Ouwerkerk · Jules G Becher
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    ABSTRACT: Selective dorsal rhizotomy is an effective treatment for spasticity in children with cerebral palsy who have a spastic motor disorder. It is hypothesized that muscle shortening is related to spasticity; the lack of stretch of a muscle is thought to be the cause of muscle shortening. If this is true, the treatment for spasticity should prevent the occurrence of muscle shortening during growth. We present the case of 1 child with cerebral palsy and spastic diplegia, for whom the treatment with selective dorsal rhizotomy was successful in improving the walking abilities. She did, however, develop muscle shortening during growth. In conclusion, the development of muscle shortening during growth in children with cerebral palsy and spastic paresis cannot be prevented by treatment for the spasticity alone.
    No preview · Article · Feb 2009 · Journal of child neurology
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    R.P. Weenink · W.J.R. Van Ouwerkerk
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    ABSTRACT: A seven year old girl presented with torticollis preceded by pharyngitis. CT scan of the cervical spine showed atlantoaxial subluxation (Grisel's syndrome). The patient was treated with pain medication, muscle relaxants and a rigid collar during a week.
    Full-text · Article · Feb 2009 · Tijdschrift voor kindergeneeskunde
  • R. Petru · S. M. Peerdeman · W. J. R. van Ouwerkerk
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    ABSTRACT: Traumatisch hersenletsel is een frequente oorzaak van morbiditeit en mortaliteit door ongevallen of mishandeling op de kinderleeftijd. Ernstig neurotrauma wordt gedefinieerd als een neurotrauma met een glasgow-comascore kleiner dan 9 op de plaats van het ongeval. Gebaseerd op de geldende richtlijnen voor de behandeling van ernstig neurotrauma bij kinderen en volwassenen en aanvullende recente literatuur wordt een overzicht gegeven van de beste huidige behandeling van deze patiënten gericht op de Nederlandse situatie. Hypotensie, shock en hypoxie zijn geassocieerd met een slechte uitkomst en moeten actief bestreden worden. Transport dient primair naar een gespecialiseerd traumacentrum te geschieden. Zo spoedig mogelijk dient een CT-scan verricht te worden, en een herhaling van dit onderzoek moet overwogen worden bij iedere neurologische verslechtering. Een operabele intracraniële bloeding met massa-effect is een indicatie voor chirurgische evacuatie. De basisbehandeling bestaat uit adequate ventilatie, normothermie, sedatie en het intact houden of optimaliseren van het interne milieu. De intracraniële druk dient door middel van frequent neurologisch onderzoek met gebruik van de (pediatrische) glasgow-comaschaal en/of via een ICP-meter te geschieden. Als behandeling van intracraniële drukverhoging zijn osmotische therapie, diepere sedatie, liquordrainage, opgelegde hypothermie, kortdurende hyperventilatie en decompressie craniëctomie effectief, hoewel de effecten op de uitkomst niet geheel duidelijk zijn. Voor het profylactisch gebruik van anti-epileptica, voor het barbituratencoma en voor spierverslappers is in het algemeen geen indicatie. Corticosteroïden zijn gecontra-indiceerd. Traumatic brain injury is a frequent cause of child morbidity and mortality resulting from both accidents and abusive head injury. Severe traumatic brain injury (TBI) is defined as brain injury with an initial (Pediatric) Glasgow Coma Score less than 9. Based on the current guidelines for the management of severe traumatic brain injury in children and adults and additional recent literature we give an overview of the current state of the art treatment of these patients as applicable to the situation in the Netherlands. Hypotension, shock and hypoxia are associated with an unfavorable outcome and need to be addressed actively. Patients should be transported directly to a specialized pediatric trauma center. The patient should receive a CT scan as soon as possible and repeating the scan should be considered with every deterioration of the neurological condition. Surgical evacuation of mass lesions should be performed as needed. Adequate ventilation, prevention of hyperthermia, sedation and maintenance of the interior environment are the cornerstones of the subsequent therapy. The patient should be frequently evaluated by neurological examination, the assessment of the (Pediatric) Glasgow Coma Scale and/ or through direct monitoring of the intracranial pressure. Hyperosmolar therapy, deeper sedation, CSF drainage, therapeutic hypothermia, short-term hyperventilation and decompressive craniectomy are effective in lowering the ICP, although their effects on long-term outcome are not fully established. There is no indication in general for anti-seizure prophylaxis, high-dose barbiturate therapy or neuromuscular blockade. The use of corticosteroids is contraindicated.
    No preview · Article · Dec 2008 · Tijdschrift voor kindergeneeskunde
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    LA Bonouvrié · P E M van Schie · J G Becher · W J R van Ouwerkerk · R J Vermeulen

    Full-text · Article · Sep 2008 · Developmental Medicine & Child Neurology
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    ABSTRACT: Selective dorsal rhizotomy at the lumbar level is a neurosurgical procedure, which reduces spasticity in the legs. Its effect has mainly been studied in children with spastic cerebral palsy. Little is known about the outcome of selective dorsal rhizotomy in patients with neurodegenerative disorders. We report the clinical course after selective dorsal rhizotomy in 2 patients with progressive spasticity. Leg spasticity was effectively and persistently reduced in both patients, facilitating care and improving sitting comfort. However, spasticity of the arms and other motor disturbances, such as spontaneous extension spasms and the ataxia, increased gradually in time. Selective dorsal rhizotomy leads to a disappearance of leg spasticity in patients with a neurodegenerative disease. Other motor signs are not influenced and may increase due to the progressive nature of the underlying disease.
    Full-text · Article · Jul 2008 · Journal of child neurology

Publication Stats

495 Citations
62.06 Total Impact Points

Institutions

  • 1998-2015
    • VU University Amsterdam
      • Department of Orthopaedic Surgery
      Amsterdamo, North Holland, Netherlands
  • 2004-2011
    • VU University Medical Center
      • • Department of Neurosurgery
      • • Rehabilitation Medicine Clinic
      Amsterdamo, North Holland, Netherlands