[Brain damage caused by exposure to organic solvents; diagnostics and disease course of chronic solvent-induced encephalopathy]

Since 1997 more than 3,000 patients have been referred to one of the two Dutch Solvent Teams with health problems that may have been caused by long-term occupational exposure to organic solvents. A diagnosis of 'chronic solvent-induced encephalopathy' was made in approximately 500 patients. The diagnostics of this disease is based on five elements: (a) symptoms in line with the diagnosis; (b) relevant exposure to an organic solvent with neurotoxic effects; (c) a clear temporal relationship between the onset of symptoms and exposure to a solvent with neurotoxic effects; (d) exclusion of other causes for the symptoms; and (e) impairment on neuropsychological assessment. Exposure to organic solvents can cause chronic health effects, which may even persist years after exposure has ceased. In general, no more serious deterioration of health is observed after exposure has ceased.

Headache in epilepsy patients: the (un)awareness of this phenomenon among Dutch neurologists

PURPOSE

Headache is a frequently heard complaint that can strongly influence quality of life. This is probably even more so in people with a chronic illness. Knowing that headache, and especially migraine, is more frequent among epilepsy patients, the knowledge concerning this problem has been studied among Dutch neurologists.

METHODS

Seven hundred and seventy two neurologists, working in 89 hospitals and two tertiary epilepsy clinics were asked to participate. Using a questionnaire, neurologists were surveyed on different subjects, e.g. whether they thought current headaches are more frequent in people with epilepsy than in the general population, their interest for epilepsy and how many patients with epilepsy visited their polyclinic per month.

RESULTS

In total, 334 questionnaires were returned (response rate of 43%) of which 18 were excluded. One third of neurologists responded affirmatively that current headaches are more prevalent among people with epilepsy and eight percent knows that this is, more specified, migraine. The number of years of experience does not influence knowledge on headaches in epilepsy patients. The interest in epilepsy and the number of epilepsy patients per month on the polyclinic does.

CONCLUSIONS

These results show that the occurrence of headache in people with epilepsy is underestimated by Dutch neurologists. This leaves an often bothersome and potentially treatable condition underexposed.

Placental telomere length decreases with gestational age and is influenced by parity: a study of third trimester live-born twins

BACKGROUND

In contrast to the postnatal period, little is known about telomere length (TL) during prenatal life. The decrease in placental TL remains unknown, although intra uterine growth retardation and preeclampsia are associated with shorter placental TL. The aim of this study is to assess the decrease of placental TL during the third trimester of gestation and to explore the role of potential "growth influencing factors".

METHODS

The study sample consisted of 329 live-born twins from the East Flanders Prospective Twin Survey. TL was determined using a multiplex quantitative PCR method. Gestational age, sex, birth order, placental characteristics, parity, maternal and paternal age, diabetes, hypertension, smoking, alcohol use, and socio economic status (SES) were considered "growth influencing factors". Bivariable multilevel regression analysis with "growth influencing factors" was performed.

RESULTS

Placental TL ranged from 4.3 kbp to 84.4 kbp with a median of 10.8 kbp. Ln(TL) decreased in a linear fashion with an estimated TL decreasing from 13.98 kbp at 28 weeks to 10.56 kbp at 42 weeks. The regression coefficient of gestational age became smaller if considered together with SES (b = -0.017; p = 0.08) or diabetes (b = -0.018; p = 0.07) and bigger if considered together with parity (b = -0.022; p = 0.02), indicating that part of the association between gestational age and telomere length is explained by these three confounding factors.

CONCLUSION

Placental TL decreases during the third trimester of gestation of live-born twins with approximately 25% indicating that telomere shortening may play a role in aging of the placenta.

[Aerotoxic syndrome: fact or fiction?]

Although the air from the turbine engines of commercial jet aircraft is used chiefly for propulsion some is also used to refresh and replenish air in the cabin. As a result of oil-seal leakage, pyrolysed engine oil or lubricating oil can contaminate cabin air via the aircraft's ventilation system, and flight crew and passengers can then inhale the combusted fumes. Exposure to emissions from cabin air, whether polluted or not, is associated with certain health risks. This phenomenon is known as the aerotoxic syndrome or 'cabin contamination'. The symptoms are non-specific, consisting predominantly of fatigue and mild cognitive impairment. Possible adverse health effects are attributed factors including organophosphate tricresyl phosphate, a component of aircraft engine oil that is potently neurotoxic.

Mutations in potassium channel kcnd3 cause spinocerebellar ataxia type 19

OBJECTIVE

To identify the causative gene for the neurodegenerative disorder spinocerebellar ataxia type 19 (SCA19) located on chromosomal region 1p21-q21.

METHODS

Exome sequencing was used to identify the causal mutation in a large SCA19 family. We then screened 230 ataxia families for mutations located in the same gene (KCND3, also known as Kv4.3) using high-resolution melting. SCA19 brain autopsy material was evaluated, and in vitro experiments using ectopic expression of wild-type and mutant Kv4.3 were used to study protein localization, stability, and channel activity by patch-clamping.

RESULTS

We detected a T352P mutation in the third extracellular loop of the voltage-gated potassium channel KCND3 that cosegregated with the disease phenotype in our original family. We identified 2 more novel missense mutations in the channel pore (M373I) and the S6 transmembrane domain (S390N) in 2 other ataxia families. T352P cerebellar autopsy material showed severe Purkinje cell degeneration, with abnormal intracellular accumulation and reduced protein levels of Kv4.3 in their soma. Ectopic expression of all mutant proteins in HeLa cells revealed retention in the endoplasmic reticulum and enhanced protein instability, in contrast to wild-type Kv4.3 that was localized on the plasma membrane. The regulatory β subunit Kv channel interacting protein 2 was able to rescue the membrane localization and the stability of 2 of the 3 mutant Kv4.3 complexes. However, this either did not restore the channel function of the membrane-located mutant Kv4.3 complexes or restored it only partially.

INTERPRETATION

KCND3 mutations cause SCA19 by impaired protein maturation and/or reduced channel function.

[Revised practice guideline 'Management of patients with mild traumatic head/brain injury']

Recently the out-of-date Dutch guideline 'Mild traumatic head/brain injury' dating from 2001 was revised under the supervision of the Dutch Institute for Healthcare Improvement (CBO). The revised guideline gives underpinned decision rules for the referral of patients to hospital, carrying out diagnostic imaging investigations, and formulating indications for admission. Mild head-brain injury is no longer an indication for a conventional skull radiograph. Adults and children aged 6 years and older no longer have to be woken regularly if they are allowed home. The guideline can be used in both primary care and on the Emergency Departments of hospitals and is applicable to both adults and children. The guideline does not address the rehabilitation or long-term care of patients with mild traumatic head/brain injury, but it does give advice on reducing the risk of long-term symptoms. Regional implementation of the guideline in primary and secondary care is recommended.

Widespread thalamic and cerebellar degeneration in a patient with a complicated hereditary spastic paraplegia (HSP)

The hereditary spastic paraplegias (HSP) are a heterogeneous group of familial movement disorders sharing progressive spastic paraplegia as a common disease sign. In the present study, we performed the first pathoanatomical investigation of the central nervous degeneration of a female patient with a complicated HSP form who suffered from progressive spastic paraplegia, dysarthria, emotional symptoms, cognitive decline and a variety of additional neuropsychological deficits. This pathoanatomical investigation revealed in addition to loss of layer V Betz pyramidal cells in the primary motor cortex, widespread cerebellar neurodegeneration (i.e., loss of Purkinje cells and neuronal loss in the deep cerebellar nuclei), extensive and severe neuronal loss in a large number of thalamic nuclei, involvement of some brainstem nuclei, as well as damage to descending (i.e., lateral and ventral corticospinal tracts) and ascending (i.e., dorsal and ventral spinocerebellar tracts, gracile fascicle) fiber tracts. In view of their known functional role, damage to these central nervous gray and white matter components offers explanations for the patient's pyramidal signs, her cerebellar, psychiatric and neuropsychological disease symptoms.

Vagus nerve stimulation for medically refractory epilepsy: A long-term follow-up study

INTRODUCTION

Vagus nerve stimulation (VNS) is thought to have a cumulative effect in time on seizure frequency reduction. There also might be other variables than reduction of seizure frequency in order to determine VNS efficacy. In this study we describe the long-term outcome of the first group of vagus nerve stimulation patients with pharmacoresistant epilepsy at the Medisch Spectrum Twente, The Netherlands.

METHODS

This long-term descriptive prospective study included 19 patients, 11 males and 8 females, aged 17-46 years with pharmacoresistant epilepsy. They had received 3-16 (mean 9) different anti-epileptic drugs and were not eligible for surgical resection of an epileptic focus. A vagus nerve stimulator was implanted in the period April 1999-October 2001. Follow-up ranges from 2 to 6 years (mean 4 years). Efficacy was measured as the percentage change in seizure rate during 1 year and then after each year follow-up of VNS compared to 5 months baseline before implantation.

RESULTS

Mean seizure reduction at 1-6 years was, respectively, 14% (n = 19), 25% (n =1 9), 29% (n = 16), 29% (n = 15), 43% (n = 9) and 50% (n = 7). Because of VNS two patients were able to start living without supervision. One patient died after 2 years of follow-up possibly as a result of SUDEP. Four patients had no apparent reduction in seizure frequency. Two of them had their stimulator removed. The other two patients however had significantly reduced post-ictal periods and seizure time and received a new pulse generator when the battery was depleted. One stimulator was switched off due to adverse effects, even though there was a positive effect on his seizure reduction. In six patients the medication regimen was changed during VNS by adding one anti-epileptic drug, however without significant change in seizure reduction. Adverse effects were hoarseness and coughing during stimulation. One patient had a temporary paralysis of his left vocal cord.

CONCLUSION

We think that VNS is an effective treatment for pharmacoresistant epilepsy and its positive effect persists during the years of follow-up. Our results suggest that seizure reduction should not be considered as the only variable of importance to describe the outcome of VNS on epilepsy and it is worthwhile to look at other outcome measures.

Cardiac responses of vagus nerve stimulation: intraoperative bradycardia and subsequent chronic stimulation

OBJECTIVES

Few adverse events on heart rate have been reported with vagus nerve stimulation (VNS) for refractory epilepsy. We describe three cases with intraoperative bradycardia during device testing.

PATIENTS AND METHODS

At our hospital 111 patients have received a VNS system. Intraoperative device testing is performed under ECG-monitoring. We reviewed the patients and their VNS-therapy follow-up outcome who experienced a change in heart rate, during device testing (Lead Test).

RESULTS

Three patients with medically refractory epilepsy showed a bradycardia during intraoperative Lead Test. Postoperative the VNS-therapy started under ECG-monitoring. No change in cardiac rhythm occurred. Subsequent chronic stimulation is uneventful. All three have reduced seizure frequency. Two already have had their second implant, without the occurrence of bradycardia.

CONCLUSION

In case of intraoperative bradycardia VNS-therapy onset should be done under ECG-monitoring. Subsequent chronic stimulation is safe in respect to heart rate. Bradycardia during intraoperative device testing is no reason to abort the operation.

Dandy-Walker complex in a boy with a 5 Mb deletion of region 1q44 due to a paternal t(1;20)(q44;q13.33)

A 10-year-old boy with vermis hypoplasia, dilatation of the fourth ventricle, enlarged cisterna magna and aplasia of the corpus callosum, consistent with the Dandy-Walker complex (DWC), and slight facial dysmorphisms, severe motor and mental retardation is presented. By combining data obtained by karyotyping, array-CGH, FISH, and multiplex ligation-mediated probe amplification (MLPA) we identified a 5 Mb deletion of the 1q44 --> qter region resulting from a paternal t(1;20)(q44;q13.33). This smallest 1q44 deletion reported so far, enabled us to significantly narrow down the number of candidate genes for the DWC in this region. Since the ZNF124 transcription factor is strongly expressed in the fetal brain it may represent a candidate gene for the DWC at 1q44.

Two cases of autosomal recessive generalized dystonia in childhood: 5 year follow-up and bilateral globus pallidus stimulation results

We report two brothers with an unknown form of early-onset familiar dystonia. Characteristic clinical features are (1) childhood-onset; (2) extrapyramidal motor symptoms; (3) dysarthria; and (4) mental retardation. Additional findings include loss of D(2)-receptors in both basal ganglia and hypoplasia of the cerebellar vermis with dilatation of the fourth ventricle and cisterna magna. There seems to be a progressive and non-progressive form of this clinical entity. Dystonic symptoms of the progressive form that occurred in one of the brothers were alleviated dramatically by bilateral internal globus pallidus (Gpi) stimulation, and the improvement has lasted now for 5 years.

Refinement of the chromosome 16 locus for benign familial infantile convulsions

Benign familial infantile convulsions (BFIC) is an autosomal dominantly inherited partial epilepsy syndrome of early childhood with remission before the age of 3 years. The syndrome has been linked to loci on chromosomes 1q23, 2q24, 16p12-q12, and 19q in various families. The aim of this study was to identify the responsible locus in four unrelated Dutch families with BFIC. Two of the tested families had pure BFIC; in one family, affected individuals had BFIC followed by paroxysmal kinesigenic dyskinesias at later age, and in one family, BFIC was accompanied by later-onset focal epilepsy in older generations. Linkage analysis was performed for the known loci on chromosomes 1q23, 2q24, 16p12-q12, and 19q. The two families with pure BFIC were linked to chromosome 16p12-q12. Using recombinants from these and other published families, the chromosome 16-candidate gene region was reduced from 21.4 Mb (4.3 cm) to 2.7 Mb (0.0 cm). For the other two families, linkage to any of the known loci was unlikely. In conclusion, we confirm the linkage of pure BFIC to chromosome 16p12-q12, with further refinement of the locus. Furthermore, the lack of involvement of the known loci in two of the families indicates further genetic heterogeneity for BFIC.

Cognitive impairment in SCA-19

The autosomal dominant cerebellar ataxias (ADCAs) are a heterogeneous group of neurodegenerative disorders characterised by progressive cerebellar dysfunction in combination with various associated features. Since 1993, ADCAs have been increasingly characterised in terms of their genetic mutation and are currently referred to as spinocerebellar ataxias (SCAs). The discovery of genetic abnormalities offers the opportunity to study the possible interaction between the identified gene mutation and cognitive function. In this study, we focus on the neuropsychological abnormalities in a Dutch ADCA family, in which a new locus was recently identified (SCA-19). The family members showed frontal-executive dysfunction, with global cognitive impairment occurring in some of the more severely affected patients. Interestingly, the neuropsychological profile of this new family seems to overlap that of individuals with various other SCAs. Apparently, similar pattern of neuronal degeneration in various SCA subtypes accounts for the neuropsychological dysfunction, which is thus not genotype specific.

Suboptimal performance on neuropsychological tests in patients with suspected chronic toxic encephalopathy

Suboptimal performance during neuropsychological testing can seriously complicate assessment in behavioral neurotoxicology. We present data on the prevalence of suboptimal performance in a group of Dutch patients with suspected chronic toxic encephalopathy (CTE) after long-term occupational exposure to solvents. One hundred and forty-five subjects referred to one of two Dutch national assessment centers for CTE were administered the Amsterdam Short-Term Memory Test (ASTM) and the Test of Memory Malingering (TOMM), two tests specifically developed for the detection of suboptimal performance. For both tests, very cautious cut-off scores were chosen with a specificity of 99%. Results indicated that suboptimal performance appears to be a substantial problem in this group of patients with suspected CTE after long-term exposure to organic solvents. Only 54% of our subjects obtained normal scores on both tests of malingering, i.e. at or above cut-off score. The two tests seemed to measure the same concept in that nearly all the subjects with low TOMM scores also had low ASTM scores. However, a higher proportion of subjects scored below the cut-off on the ASTM than on the TOMM.

[Meningitis due to Listeria monocytogenes as a complication of infliximab therapy]

A 41-year-old woman was admitted to the hospital with meningitis caused by Listeria monocytogenes. Because of her Crohn's disease she used prednisolone and azathioprine. Two weeks before presenting with meningitis, infliximab had been given as the other immunosuppressant drugs had no effect. This tumour necrosis factor alpha (TNF alpha) blocking agent is known to increase the risk of opportunistic infections. This is the first Dutch patient described with meningitis caused by L. monocytogenes after treatment with infliximab. She recovered after antibiotic therapy. When antibiotic treatment is chosen, the possibility of opportunistic infections in patients who use infliximab concurrently with other immunosuppressant drugs should be taken into account.

Benign familial infantile convulsions: a clinical study of seven Dutch families

Benign familial infantile convulsions (BFIC) is a recently identified partial epilepsy syndrome with onset between 3 and 12 months of age. We describe the clinical characteristics and outcome of 43 patients with BFIC from six Dutch families and one Dutch-Canadian family and the encountered difficulties in classifying the syndrome. Four families had a pure BFIC phenotype; in two families BFIC was accompanied by paroxysmal kinesigenic dyskinesias; in one family BFIC was associated with later onset focal epilepsy in older generations. Onset of seizures was between 6 weeks and 10 months, and seizures remitted before the age of 3 years in all patients with BFIC. In all, 29 (67%) of the 43 patients had been treated with anti-epileptic drugs for a certain period of time. BFIC is often not recognized as (hereditary) epilepsy by the treating physician. Seizures often remit shortly after the start of anti-epileptic drugs but, because of the benign course of the syndrome and the spontaneous remission of seizures, patients with low seizure frequency do not necessarily have to be treated. If prescribed, anti-epileptic drugs can probably be withdrawn after 1 or 2 years of seizure freedom.

[Vagus nerve stimulation in patients with drug-resistant epilepsy]

OBJECTIVE

To describe the mechanism and first results of vagus nerve stimulation at the Medisch Spectrum Twenty, the Netherlands, for the treatment of patients with drug-resistant epilepsy.

DESIGN

Descriptive retrospective.

METHOD

Fifteen patients, 8 male and 7 female, aged 18-45 years with drug-resistant epilepsy, who were not eligible for surgical resection of an epileptic focus, received a vagus nerve stimulator implant in the period April 1999-December 2000. Whilst the vagus nerve stimulator was being adjusted, the medication remained unchanged.

RESULTS

Due to vagus nerve stimulation the mean seizure frequency decreased by 32% (range: +20% to -100%). In 6 patients there was a strong reduction in seizure frequency, in 3 there was a mild reduction, and in 6 patients there was no apparent effect. The most common adverse events during stimulation were a mild prickly cough and a change of voice during stimulation. In one patient a temporary left vocal cord paralysis was observed, which may possibly have been a result of the procedure.

CONCLUSION

Vagus nerve stimulation is an effective means of treatment for drug-resistant epilepsy and is therefore a treatment option that deserves more attention in the Netherlands.

Routine diagnostic procedures for chronic encephalopathy induced by solvents: survey of experts

OBJECTIVES

To study the routine diagnostic procedures used in different countries for chronic toxic encephalopathy (CTE) induced by solvents.

METHODS

By means of a postal questionnaire selected international experts were asked about the methods they use to diagnose patients suspected of having CTE induced by solvents, the number of patients, entrance criteria, and the results of these diagnostic procedures.

RESULTS

18 Experts working in 18 diagnostic centres responded. Most of them agreed that a diagnostic procedure for CTE induced by solvents should contain an interview and neurological, physical, and neuropsychological examinations. However, the tests used were very different, as were the classifications for CTE. Depending on the institute, a diagnosis of CTE was made in 6%--70% of the referred patients. The proportion of patients with CTE stage I ranged from 0% to 33%, stage II from 5% to 100%, and stage III from 0% to 95%.

CONCLUSION

The intentions of the two 1985 conferences that aimed at clarity and uniformity of diagnosis of CTE induced by solvents are far from reached. It is possible, now the conditions are more favourable, to aim at this important goal and recommend some refinement of the then proposed criteria.

Malattia leventinese presenting with subretinal neovascular membrane and hemorrhage

PURPOSE

To report a case of malattia leventinese involving subretinal hemorrhage.

METHODS

Case report.

RESULTS

Two weeks after initial presentation, the visual acuity of this 34-year-old man decreased to LE: 20/100. Funduscopic evaluation revealed a subretinal hemorrhage involving the center of the foveal in the left eye that was interpreted as secondary to a neovascular membrane on fluorescein angiography. The patient did well after the removal of the submacular material by pars plana vitrectomy.

CONCLUSION

Patients with malattia leventinese may occasionally present with submacular hemorrhage. Prompt diagnosis and intervention may enhance the patient's chance for visual improvement.