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Ralph T W M Thomeer

Publications and source records attributed to Ralph T W M Thomeer.

10 recordsLinked to original sources
PubMed2006

Cost-effectiveness of microendoscopic discectomy versus conventional open discectomy in the treatment of lumbar disc herniation: a prospective randomised controlled trial [ISRCTN51857546].

BACKGROUND: Open discectomy is the standard surgical procedure in the treatment of patients with long-lasting sciatica caused by lumbar disc herniation. Minimally invasive approaches such as microendoscopic discectomy have gained attention in recent years. Reduced tissue trauma allows early ambulation, short hospital stay and quick resumption of daily activities. A comparative cost-effectiveness study has not been performed yet. We present the design of a randomised controlled trial on cost-effectiveness of microendoscopic discectomy versus conventional open discectomy in patients with lumbar disc herniation. METHODS/DESIGN: Patients (age 18-70 years) presenting with sciatica due to lumbar disc herniation lasting more than 6-8 weeks are included. Patients with disc herniation larger than 1/3 of the spinal canal diameter, or disc herniation less than 1/3 of the spinal canal diameter with concomitant lateral recess stenosis or sequestration, are eliglible for participation. Randomisation into microendoscopic discectomy or conventional unilateral transflaval discectomy will take place in the operating room after induction of anesthesia. The length of skin incision is equal in both groups. The primary outcome measure is the functional assessment of the patient, measured by the Roland Disability Questionnaire for Sciatica, at 8 weeks and 1 year after surgery. We will also evaluate several other outcome parameters, including perceived recovery, leg and back pain, incidence of re-operations, complications, serum creatine kinase, quality of life, medical consumption, absenteeism and costs. The study is a randomised prospective multi-institutional trial, in which two surgical techniques are compared in a parallel group design. Patients and research nurses are kept blinded of the allocated treatment during the follow-up period of 2 years. DISCUSSION: Currently, open discectomy is the golden standard in the surgical treatment of lumbar disc herniation. Whether microendoscopic discectomy is more cost-effective than unilateral transflaval discectomy has to be determined by this trial.

Adult↗
PubMed2005

Prolonged conservative treatment or 'early' surgery in sciatica caused by a lumbar disc herniation: rationale and design of a randomized trial [ISRCT 26872154].

BACKGROUND: The design of a randomized multicenter trial is presented on the effectiveness of a prolonged conservative treatment strategy compared with surgery in patients with persisting intense sciatica (lumbosacral radicular syndrome). METHODS/DESIGN: Patients presenting themselves to their general practitioner with disabling sciatica lasting less than twelve weeks are referred to the neurology outpatient department of one of the participating hospitals. After confirmation of the diagnosis and surgical indication MRI scanning is performed. If a distinct disc herniation is discerned which in addition covers the clinically expected site the patient is eligible for randomization. Depending on the outcome of the randomization scheme the patient will either be submitted to prolonged conservative care or surgery. Surgery will be carried out according to the guidelines and between six and twelve weeks after onset of complaints. The experimental therapy consists of a prolonged conservative treatment under supervision of the general practitioner, which may be followed by surgical intervention in case of persisting or progressive disability. The main primary outcome measure is the disease specific disability of daily functioning. Other primary outcome measures are perceived recovery and intensity of legpain. Secondary outcome measures encompass severity of complaints, quality of life, medical consumption, absenteeism, costs and preference. The main research question will be answered at 12 months after randomization. The total follow-up period covers two years. DISCUSSION: Evidence is lacking concerning the optimal treatment of lumbar disc induced sciatica. This pragmatic randomized trial, focusses on the 'timing' of intervention, and will contribute to the decision of the general practictioner and neurologist, regarding referral of patients for surgery.

Humans↗
PubMed2004

Electrophysiology and morphometry of the Aalpha- and Abeta-fiber populations in the normal and regenerating rat sciatic nerve.

We studied electrophysiological and morphological properties of the Aalpha- and Abeta-fibers in the regenerating sciatic nerve to establish whether these fiber types regenerate in numerical proportion and whether and how the electrophysiological properties of these fiber types are adjusted during regeneration. Compound action potentials were evoked from isolated sciatic nerves 12 weeks after autografting. Nerve fibers were gradually recruited either by increasing the stimulus voltage from subthreshold to supramaximal levels or by increasing the interval between two supramaximal stimuli to obtain the cumulative distribution of the extracellular firing thresholds and refractory periods, respectively. Thus, the mean conduction velocity (MCV), the maximal charge displaced during the compound action potential (Q(max)), the mean firing threshold (V(50)), and the mean refractory period (t(50)) were determined. The number of myelinated nerve fibers and their fiber diameter frequency distributions were determined in the peroneal nerve. Mathematical modeling applied to fiber recruitment and diameter distributions allowed discrimination of the Aalpha- and Abeta-fiber populations. In regenerating nerves, the number of Aalpha-fibers increased fourfold while the number of Abeta-fibers did not change. In regenerating Aalpha- and Abeta-fibers, the fiber diameter decreased and V(50) and t(50) increased. The regenerating Aalpha-fibers' contribution to Q(max) decreased considerably while that of the Abeta-fibers remained the same. Correlation of the electrophysiological data to the morphological data provided indications that the ion channel composition of both the Aalpha- and Abeta-fibers are altered during regeneration. This demonstrates that combining morphometric and electrophysiological analysis provides better insight in the changes that occur during regeneration.

Action Potentials↗
PubMed2004

Evaluation of suprascapular nerve neurotization after nerve graft or transfer in the treatment of brachial plexus traction lesions.

OBJECT: The aim of this retrospective study was to evaluate the restoration of shoulder function by means of suprascapular nerve neurotization in adult patients with proximal C-5 and C-6 lesions due to a severe brachial plexus traction injury. The primary goal of brachial plexus reconstructive surgery was to restore biceps muscle function and, secondarily, to reanimate shoulder function. METHODS: Suprascapular nerve neurotization was performed by grafting the C-5 nerve in 24 patients and by accessory or hypoglossal nerve transfer in 29 patients. Additional neurotization involving the axillary nerve was performed in 18 patients. Postoperative needle electromyography studies of the supraspinatus, infraspinatus, and deltoid muscles showed signs of reinnervation in most patients; however, active glenohumeral shoulder function recovery was poor. In nine (17%) of 53 patients supraspinatus muscle strength was Medical Research Council (MRC) Grade 3 or 4 and in four patients (8%) infraspinatus muscle power was MRC Grade 3 or 4. In 18 patients in whom deltoid muscle reinnervation was attempted, MRC Grade 3 or 4 function was demonstrated in two (11%). In the overall group, eight patients (15%) exhibited glenohumeral abduction with a mean of 44 +/- 17 degrees (standard deviation [SD]; median 45 degrees) and four patients (8%) exhibited glenohumeral exorotation with a mean of 48 +/- 24 degrees (SD; median 53 degrees). In only three patients (6%) were both functions regained. CONCLUSIONS: The reanimation of shoulder function in patients with proximal C-5 and C-6 brachial plexus traction injuries following suprascapular nerve neurotization is disappointingly low.

Adolescent↗
PubMed2003

Repair of ventral root avulsion using autologous nerve grafts in cats.

This study focuses on the capacity of motor axons to elongate from the spinal cord through an autologous nerve graft into a spinal nerve. Applying a ventral surgical approach, C7 ventral roots were avulsed from the cord in 12 cats. Autologous saphenous nerve grafts were implanted into the cord at the ventral root outlet site and coaptated to the spinal nerve. Outgrowth of axons was studied at survival times 7, 14, 30, 60 and 120 days, respectively. The results showed horseradish peroxidase positive motoneurons in the C7 ventral horn after retrograde labeling, as well as neurofilament and acetylcholinesterase positive axons in the entire trajectory from spinal cord to spinal nerve. Neurotization of the C7 spinal nerve started between 14 and 30 days after graft implantation. In addition electrophysiology provided evidence that outgrowing axons had re-established functional contact with the spinodeltoid muscle at 120 days after implantation.

Animals↗
PubMed2003

Functional magnetic resonance imaging and control over the biceps muscle after intercostal-musculocutaneous nerve transfer.

OBJECT: Recent progress in the understanding of cerebral plastic changes that occur after an intercostal nerve (ICN)-musculocutaneous nerve (MCN) transfer motivated a study with functional magnetic resonance (fMR) imaging to map reorganization in the primary motor cortex. METHODS: Eleven patients with traumatic root avulsions of the brachial plexus were studied. Nine patients underwent ICN-MCN transfer to restore biceps function and two patients were studied prior to surgery. The biceps muscle recovered well in seven patients who had undergone surgery and remained paralytic in the other two patients. Maps of neural activity within the motor cortex were generated for both arms in each patient by using fMR imaging, and the active pixels were counted. The motor task consisted of biceps muscle contraction. Patients with a paralytic biceps were asked to contract this muscle virtually. The location and intensity of motor activation of the seven surgically treated arms that required good biceps muscle function were compared with those of the four arms with a paralytic biceps and with activity obtained in the contralateral hemisphere regulating the control arms. Activity could be induced in the seven surgically treated patients whose biceps muscles had regained function and was localized within the primary motor area. In contrast, activity could not be induced in the four patients whose biceps muscles were paralytic. Neither the number of active pixels nor the mean value of their activations differed between the seven arms with good biceps function and control arms. The weighted center of gravity of the distribution of activity also did not appear to differ. CONCLUSIONS: Reactivation of the neural input activity for volitional biceps control after ICN-MCN transfer, as reflected on fMR images, is induced by successful biceps muscle reinnervation. In addition, the restored input activity does not differ from the normal activity regulating biceps contraction and, therefore, has MCN acceptor qualities. After ICN-MCN transfer, cerebral activity cannot reach the biceps muscle following the normal nervous system pathway. The presence of a common input response between corticospinal neurons of the ICN donor and the MCN acceptor seems crucial to obtain a functional result after transfer. It may even be the case that a common input response between donor and acceptor needs to be present in all types of nerve transfer to become functionally effective.

Adolescent↗
PubMed2002

Repair of ventral root avulsions of the brachial plexus: a review.

Traumatic root avulsions of the brachial plexus constitute a devastating lesion resulting in loss of function of the upper limb and carry a large emotional and socioeconomic impact. In this literature survey, the different factors involved in root avulsion are discussed in combination with various surgical techniques for repair of experimental ventral root avulsion. Until now repair of root avulsions did not generate unequivocal proof of recovery of limb function, particularly of the hand. More experimental studies are needed to assess the efficacy of several repair techniques, the optimal timing for surgery, and the complications associated with spinal cord manipulation.

Animals↗
PubMed2002

High risk of acute deterioration in patients harboring symptomatic colloid cysts of the third ventricle.

OBJECT: Patients harboring colloid cysts of the third ventricle can present with acute neurological deterioration, or the first indication of the lesion may appear when the patient suddenly dies. The risk of such an occurrence in a patient already identified as harboring a colloid cyst is unknown. The goal of this study was to estimate the risk of acute deterioration in patients with colloid cysts. METHODS: A retrospective study was made of a cohort of patients with newly diagnosed colloid cysts who were recruited in The Netherlands between January 1, 1993, and December 31, 1997. Seventy-eight patients were identified, all of whom displayed symptoms. Twenty-five patients (32%) presented with symptoms of acute deterioration; four patients died suddenly and the cysts were discovered at autopsy. The overall mortality rate was 12%. Results of a multivariate logistic regression analysis demonstrated that no subgroup of patients presenting without acute deterioration could be identified on the basis of patient age, duration of symptoms, cyst size, or the presence of hydrocephalus. The national incidence of colloid cysts in The Netherlands is 1/10(6) person-years; the prevalence was estimated to be 1800 asymptomatic colloid cysts. CONCLUSIONS: Acute deterioration was a frequent presentation among a national cohort of Dutch patients harboring symptomatic colloid cysts. The risk of acute deterioration in a symptomatic patient with a colloid cyst in The Netherlands is estimated to be 34%. The estimated risk for an asymptomatic patient with an incidental colloid cyst is significantly lower. These results strongly advocate the selection of surgical treatment for patients with symptomatic colloid cysts.

Acute Disease↗
PubMed2002

Nerve root repair.

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Brachial Plexus↗