The role of nanoparticles in bleed air in the etiology of Aerotoxic Syndrome: A review of cabin air-quality studies of 2003-2023

Aerotoxic Syndrome may develop as a result of chronic, low-level exposure to organophosphates (OPs) and volatile organic compounds in the airplane cabin air, caused by engine oil leaking past wet seals. Additionally, acute high-level exposures, so-called "fume events," may occur. However, air quality monitoring studies concluded that levels of inhaled chemicals might be too low to cause adverse effects. The presence of aerosols of nanoparticles (NPs) in bleed air has often been described. The specific hypothesis is a relation between NPs acting as a vector for toxic compounds in the etiology of the Aerotoxic Syndrome. These NPs function as carriers for toxic engine oil compounds leaking into the cabin air. Inhaled by aircrew NPs carrying soluble and insoluble components deposit in the alveolar region, where they are absorbed into the bloodstream. Subsequently, they may cross the blood-brain barrier and release their toxic compounds in the central nervous system. Olfactory absorption is another route for NPs with access to the brain. To study the hypothesis, all published in-flight measurement studies (2003-2023) of airborne volatile (and low-volatile) organic pollutants in cabin air were reviewed, including NPs (10-100 nm). Twelve studies providing data for a total of 387 flights in 16 different large-passenger jet aircraft types were selected. Maximum particle number concentrations (PNC) varied from 104 to 2.8 × 106 #/cm3 and maximum mass concentrations from 9 to 29 μg/m3. NP-peaks occurred after full-power take-off, in tailwind condition, after auxiliary power unit (APU) bleed air introduction, and after air conditioning pack failure. Chemical characterization of the NPs showed aliphatic hydrocarbons, black carbon, and metallic core particles. An aerosol mass-spectrometry pattern was consistent with aircraft engine oil. It is concluded that chronic exposure of aircrew to NP-aerosols, carrying oil derivatives, maybe a significant feature in the etiology of Aerotoxic Syndrome. Mobile NP measuring equipment should be made available in the cockpit for long-term monitoring of bleed air. Consequently, risk assessment of bleed air should include monitoring and analysis of NPs, studied in a prospective cohort design.

The role of carbon monoxide in aerotoxic syndrome

Chronic low-level exposure to toxic compounds in airplane cabin air may result in Aerotoxic Syndrome (AS). Aetiologic agents are organophosphates and numerous volatile organic hydrocarbons originating from leaks of engine oil and hydraulic fluids. Despite a documented history spanning decades, the role of carbon monoxide remains controversial. What evidence exists that carbon monoxide (CO), present in the cocktail of toxic compounds in bleed air, contributes to the AS? We selected 22 publications encompassing 888 flights with 18 different aircraft types. In one study of 100 flights, fume events were confirmed in 38. Four studies were initialized after air quality incidents. The cabin CO concentrations could be categorized in three levels, 1) low (<5 ppm), without health implications, 2) moderate (5-10 ppm) with probably health implications in case of chronic exposure, and 3) high > 10 ppm, with health effects in case of acute and chronic exposure. These levels were recorded in 12, 6 and 4 studies respectively. In the six studies in category 2, max CO concentrations ranged from 5.8-9.4 ppm. The four studies with CO > 10 ppm comprised 376 of the 888 flights (42%) with six aircraft types. Toxic CO levels ranging between 13-60 ppm were identified in at least 129 of 888 (14.5%) flights. In one study with high CO levels four flight attendants were diagnosed with CO poisoning with elevated HbCO levels. Max CO levels in aviation are either the same or higher than current occupational exposure limits (OEL) for ground-based workplace exposures or levels for urban street transport environments. Specific aspects of aviation should be taken into consideration: the effect of low(er) air pressure at high altitudes increasing the toxicity of CO, and the binding of CO to CYP enzymes, leading to impaired organophosphate detoxification. We conclude that CO must be considered an important factor in the lubrication derived cocktail of airborne toxic compounds causing AS. In line with the WHO advice, a reduction of the OEL to 5 ppm over 8 hr time weighted average (TWA) for aircrew is strongly recommended. And we advocate continuous monitoring during all phases of flight and installation of CO detectors in the air supply ducts to the aircraft cabin.

Chronic Traumatic Encephalopathy in Soccer Players: Review of 14 Cases

OBJECTIVE

Exposure to repetitive sports-related concussions or (sub)concussive head trauma may lead to chronic traumatic encephalopathy (CTE). Which impact (heading or concussion) poses the greatest risk of CTE development in soccer players?

DESIGN

Narrative review.

SETTING

Teaching hospital and University of Applied sciences.

PATIENTS

A literature search (PubMed) was conducted for neuropathologic studies in the period 2005-December 2022, investigating soccer players with dementia and a CTE diagnosis, limited to English language publications. 210 papers were selected for final inclusion, of which 7 papers described 14 soccer players.

ASSESSMENT

Magnetic resonance imaging studies in soccer players show that lifetime estimates of heading numbers are inversely correlated with cortical thickness, grey matter volume, and density of the anterior temporal cortex. Using diffusion tensor imaging-magnetic resonance imaging, higher frequency of headings-particularly with rotational accelerations-are associated with impaired white matter integrity. Serum neurofilament light protein is elevated after heading.

MAIN OUTCOME MEASURES

Chronic traumatic encephalopathy pathology, history of concussion, heading frequency.

RESULTS

In 10 of 14 soccer players, CTE was the primary diagnosis. In 4 cases, other dementia types formed the primary diagnosis and CTE pathology was a concomitant finding. Remarkably, 6 of the 14 cases had no history of concussion, suggesting that frequent heading may be a risk for CTE in patients without symptomatic concussion. Rule changes in heading duels, management of concussion during the game, and limiting the number of high force headers during training are discussed.

CONCLUSIONS

Data suggest that heading frequency and concussions are associated with higher risk of developing CTE in (retired) soccer players. However based on this review of only 14 players, questions persist as to whether or not heading is a risk factor for CTE or long-term cognitive decline.

Health consequences of exposure to aircraft contaminated air and fume events: a narrative review and medical protocol for the investigation of exposed aircrew and passengers

Thermally degraded engine oil and hydraulic fluid fumes contaminating aircraft cabin air conditioning systems have been well documented since the 1950s. Whilst organophosphates have been the main subject of interest, oil and hydraulic fumes in the air supply also contain ultrafine particles, numerous volatile organic hydrocarbons and thermally degraded products. We review the literature on the effects of fume events on aircrew health. Inhalation of these potentially toxic fumes is increasingly recognised to cause acute and long-term neurological, respiratory, cardiological and other symptoms. Cumulative exposure to regular small doses of toxic fumes is potentially damaging to health and may be exacerbated by a single higher-level exposure. Assessment is complex because of the limitations of considering the toxicity of individual substances in complex heated mixtures.There is a need for a systematic and consistent approach to diagnosis and treatment of persons who have been exposed to toxic fumes in aircraft cabins. The medical protocol presented in this paper has been written by internationally recognised experts and presents a consensus approach to the recognition, investigation and management of persons suffering from the toxic effects of inhaling thermally degraded engine oil and other fluids contaminating the air conditioning systems in aircraft, and includes actions and investigations for in-flight, immediately post-flight and late subsequent follow up.

Fetuses and infants with Amyoplasia congenita in congenital Zika syndrome: The evidence of a viral cause. A narrative review of 144 cases

OBJECTIVES

Amyoplasia congenita is the most frequent type of arthrogryposis causing fetal hypokinesia, leading to congenital contractures at birth. The pathogenesis is thought to be impaired blood circulation to the fetus early in pregnancy, with hypotension and hypoxia damaging the anterior horn cells. In animal studies however a prenatal infection with a poliomyelitis-like viral agent was demonstrated. Congenital Zika virus syndrome (CZVS) has recently been described in infants with severe microcephaly, and in 10-25% of cases arthrogryposis.

METHODS

A search in PubMed for CZVS yielded 124 studies. After a selection for arthrogryposis, 35 papers were included, describing 144 cases. The studies were divided into two categories. 1) Those (87 cases) focussing on imaging or histological data of congenital brain defects, contained insufficient information to link arthrogryposis specifically to lesions of the brain or spinal motor neuron. 2) In the other 57 cases detailed clinical data could be linked to neurophysiological, imaging or histological data.

RESULTS

In category 1 the most frequent brain abnormalities in imaging studies were ventriculomegaly, calcifications (subcortical, basal ganglia, cerebellum), hypoplasia of the brainstem and cerebellum, atrophy of the cerebral cortex, migration disorders and corpus callosum anomalies. In category 2, in 38 of 57 cases clinical data were indicative of Amyoplasia congenita. This diagnosis was confirmed by electromyographic findings (13 cases), by MRI (37 cases) or histology (12 cases) of the spinal cord. The latter showed small or absent lateral corticospinal tracts, and cell loss and degeneration of motor neuron cells. Zika virus-proteins and flavivirus-like particles were detected in cytoplasm of spinal neurons.

CONCLUSION

The phenotype of arthrogryposis in CZVS is consistent with Amyoplasia congenita. These findings warrant search for an intrauterine infection with any neurotropic viral agent with affinity to spinal motor neurons in neonates with Amyoplasia.

A Child Presenting with a Glasgow Coma Scale Score of 13: Mild or Moderate Traumatic Brain Injury? A Narrative Review

OBJECTIVE

The objective of this article was to compare children with traumatic brain injury (TBI) and Glasgow Coma Scale score (GCS) 13 with children presenting with GCS 14 and 15 and GCS 9 to 12.

DATA SOURCE

We searched PubMed for clinical studies of children of 0 to 18 years of age with mild TBI (mTBI) and moderate TBI, published in English language in the period of 2000 to 2020.

STUDY SELECTION

We selected studies sub-classifying children with GCS 13 in comparison with GCS 14 and 15 and 9 to 12. We excluded reviews, meta-analyses, non-U.S./European population studies, studies of abusive head trauma, and severe TBI.

DATA SYNTHESIS

Most children (>85%) with an mTBI present at the emergency department with an initial GCS 15. A minority of only 5% present with GCS 13, 40% of which sustain a high-energy trauma. Compared with GCS 15, they present with a longer duration of unconsciousness and of post-traumatic amnesia. More often head computerized tomography scans show abnormalities (in 9-16%), leading to neurosurgical intervention in 3 to 8%. Also, higher rates of severe extracranial injury are reported. Admission is indicated in more than 90%, with a median length of hospitalization of more than 4 days and 28% requiring intensive care unit level care. These data are more consistent with children with GCS 9 to 12. In children with GCS 15, all these numbers are much lower.

CONCLUSION

We advocate classifying children with GCS 13 as moderate TBI and treat them accordingly.

[Flying and COVID-19: options to reduce the risk of transmission]

With air travel continuing after the SARS-CoV-2 pandemic as before, is there a risk of in-flight-transmission? We found 18 papers describing a total number of 306 index patients on 150 flights, 79 infected passengers and four infected cabin crew. Infection transmission within the aircraft cabin depends on flight occupancy, proximity to the index patient, duration of flight and the prevailing virus variant. A negative PCR-test has a sensitivity of 95 %, around 5 % of travelers will get a false negative result. Airborne transmission of virus-containing saliva droplets (aerosols) is considered the most important infection mechanism; infection via contaminated surfaces is less common. Strict distancing, with an empty middle seat, is essential. The risk of in-flight transmission can be further minimized by mandatory masking, restricting passenger movements, restricting meals and beverages, frequent hand sanitizing and complying to rules while boarding or at disembarkation.

Susceptibility-Weighted MRI and Microbleeds in Mild Traumatic Brain Injury: Prediction of Posttraumatic Complaints?

BACKGROUND

Only in 7-15% of patients with mild traumatic brain injury (mTBI), traumatic CT-abnormalities are found. Nevertheless, 40% of mTBI patients suffer from posttraumatic complaints not resolving after 6 months. We discuss the ability of susceptibility-weighted imaging (SWI), sensitive for microbleeds, to detect more subtle brain abnormalities.

SUMMARY

After a search on PubMed, we selected 15 studies on SWI in adult mTBI patients; 11 studies on 3T MRI, and 4 studies on 1.5T MRI. All 1.5T studies showed that, compared to T2, gradient echo, diffusion-weighted imaging, or fluid-attenuated inversion recovery sequences, SWI is more sensitive for microbleeds. Only two 1.5T studies described the association between SWI findings and outcome. In 3 of the 4 studies, no control group was present. The mean number of microbleeds varied from 3.2 to 6.4 per patient. In the 3T studies, the percentage of patients with traumatic microbleeds varied from 5.7 to 28.8%, compared to 0-13.3% in normal controls. Microbleeds were particularly located subcortical or juxtacortical. The number of microbleeds in mTBI varied from 1 to 10 per patient. mTBI patients with microbleeds appeared to have higher symptom severity at 12 months and perform worse on tests of psychomotor speed and speed of information processing after 3 and 12 months, compared to mTBI patients without microbleeds. Key Messages: There is some evidence that traumatic microbleeds predict cognitive outcome and persistent posttraumatic complaints in patients with mTBI.

A Pyramidal Cause of a Cerebellar Ataxia: HSP-7

A 43-year-old man presented with a slowly progressive fatigue and coordination problems, coupled with a radiological appearance of diffuse atrophy, especially in the cerebellar hemispheres. The diagnostic process was challenging because initially the additional investigations were focused on a cerebellar ataxia. In the following months, his ataxic gait developed in a more spastic pattern and whole exome sequencing revealed mutations in the SPG7 gene, confirming a diagnosis of hereditary spastic paraplegia. Therefore, the authors call for an extension of genetic panels in ataxia patients.

Patients with mild traumatic brain injury and acute neck pain at the emergency department are a distinct category within the mTBI spectrum: a prospective multicentre cohort study

BACKGROUND

Acute neck pain (ANP) has recently been demonstrated to be a predictor of persistent posttraumatic complaints after mild traumatic brain injury (mTBI). The aim of this study was to determine specific characteristics of patients with ANP following mTBI, their posttraumatic complaints and relationship with functional outcome.

METHODS

Data from a prospective follow-up study of 922 mTBI patients admitted to the emergency department (ED) in three level-one trauma centres were analysed. Patients were divided into two groups: 156 ANP patients and 766 no acute neck pain (nANP) patients. Posttraumatic complaints were evaluated 2 weeks and 6 months post-injury using standardized questionnaires and functional outcome was evaluated at 6 months with the Glasgow Outcome Scale Extended (GOSE).

RESULTS

ANP patients were more often female (p < 0.01), younger (38 vs. 47 years, p < 0.01) with more associated acute symptoms at the ED (p < 0.05) compared to nANP patients. More motor vehicle accidents (12% vs. 6%, p = 0.01) and less head wounds (58% vs. 73%, p < 0.01) in ANP patients indicated 'high-energy low-impact' trauma mechanisms. ANP patients showed more posttraumatic complaints 2 weeks and 6 months post-injury (p < 0.05) and more often incomplete recovery (GOSE < 8) was present after 6 months (56% vs. 40%, p = 0.01).

CONCLUSIONS

MTBI patients with acute neck pain at the ED constitute a distinct group within the mTBI spectrum with specific injury and demographic characteristics. Early identification of this at risk group already at the ED might allow specific and timely treatment to avoid development of incomplete recovery.

[An abnormal CT scan following a mild traumatic brain injury; what then?]

CT scan reveals traumatic intracranial abnormalities in fewer than 10% of patients following mild traumatic brain injury (mTBI). Management policy in these patients is not clear. Clinical or radiological deterioration occurs in 10-20% of this risk group, usually within 24 hours and often without neurosurgical consequences. Patients with mTBI and subarachnoid blood or small foci of contusion do not need to be admitted to medium/high care or to the ICU. This is warranted in patients fulfilling the following criteria: age > 65 years; a Glasgow Coma Scale (GCS) score < 15; anticoagulant use; or multiple trauma. It is also warranted by fulfilment of one or more of the following CT-criteria: shift of the midline; subdural or epidural haematoma; a temporal or subfrontal focus of contusion; or intraparenchymatous bleeding > 10 ml. Repeated CT-scan is only indicated in case of clinical deterioration. Transfer to a neurosurgical centre is not necessary in the majority of patients with mTBI and CT abnormalities.

Aerotoxic syndrome, discussion of possible diagnostic criteria

Introduction: The term aerotoxic syndrome (ATS) was proposed 20 years ago to describe a constellation of symptoms reported by pilots and cabin crew following exposure to hydraulic fluids, engine oil, and pyrolysis products during flight. Hydraulic fluids and engine oil contain a large number of potentially toxic chemicals, including various organophosphate compounds (OPCs). However, ATS is not yet recognised as a valid diagnosis in aviation or general medicine, because the incidence and aetiology continues to be debated.Discussion: Early studies report findings from symptom surveys or cognitive assessments of small samples of self-selected aircrew, but objective measures of exposure were lacking. Over the last decade, researchers have used more sophisticated techniques to measure exposure, such as on board monitoring studies and biomarkers of exposure (e.g., reduced levels of serum butyrylcholinesterases [BChE]) and more sophisticated techniques to detect nervous system injuries such as fMRI and autoantibody testing. Consideration has also been given to inter-individual differences in the ability to metabolise certain chemical compounds as a result of genetic polymorphisms and exclusion of other potential causes of ill health.Conclusions: We discuss factors which suggest a diagnosis of probable ATS; recommend an assessment protocol which incorporates the aforementioned techniques; and propose diagnostic criteria for probable ATS, based on our previously reported findings in aircrew and the results of recent studies.

Three patients with probable aerotoxic syndrome

Introduction: "Aerotoxic syndrome" is a debated entity. Regulatory authorities consider long-term health effects to be an unlikely consequence of exposure to contaminated air because several air quality monitoring studies report low concentrations of toxic chemicals in cabin air. We describe two pilots and one flight attendant, who developed ill health during their flying career which improved after cessation of flying.Case details: The most frequently reported symptoms were headache, balance problems, fatigue, gastro-intestinal complaints and cognitive impairment. One of these patients had reduced levels of butyrylcholinesterase after a flight suggesting exposure to organophosphate compounds had occurred. All three were found to have elevated neuronal and glial auto-antibodies, biomarkers of central nervous system injury, and all three had genetic polymorphisms of paraoxonase (PON-1) and two of cytochrome P450, leading to a reduced ability to metabolize organophosphate compound (OPs).Discussion: A similar constellation of symptoms has been described in other studies of aircrew, although objective evidence of exposure is lacking in most of these studies. Reduced levels of butyrylcholinesterases in one of our cases is suggestive of causation and elevated neuronal and glial autoantibodies provide objective evidence of damage to the central nervous system. We consider further research is warranted.

Chronic solvent-induced encephalopathy: course and prognostic factors of neuropsychological functioning

PURPOSE

Working in conditions with daily exposure to organic solvents for many years can result in a disease known as chronic solvent-induced encephalopathy (CSE). The aims for this study were to describe the neuropsychological course of CSE after first diagnosis and to detect prognostic factors for neuropsychological impairment after diagnosis.

METHODS

This prospective study follows a Dutch cohort of CSE patients who were first diagnosed between 2001 and 2011 and underwent a second neuropsychological assessment 1.5-2 years later. Cognitive subdomains were assessed and an overall cognitive impairment score was calculated. Paired t tests and multivariate linear regression analyses were performed to describe the neuropsychological course and to obtain prognostic factors for the neuropsychological functioning at follow-up.

RESULTS

There was a significant improvement on neuropsychological subdomains at follow-up, with effect sizes between small and medium (Cohen's d 0.27-0.54) and a significant overall improvement of neuropsychological impairment with a medium effect size (Cohen's d 0.56). Prognostic variables for more neuropsychological impairment at follow-up were a higher level of neuropsychological impairment at diagnosis and having a comorbid diagnosis of a psychiatric disorder at diagnosis.

CONCLUSIONS

Results are in line with previous research on the course of CSE, stating that CSE is a non-progressive disease after cessation of exposure. However, during follow-up the percentage patients with permanent work disability pension increased from 14 to 37%. Preventive action is needed in countries where exposure to organic solvents is still high to prevent new cases of CSE.

Prediction of work resumption and sustainability up to 1 year after mild traumatic brain injury

Objective:

To study return to work (RTW) after mild traumatic brain injury (mTBI) at several intervals after injury and to predict RTW on the basis of occupational factors in addition to demographic, personality, and injury-related factors at 6 and 12 months after injury.

Methods:

This was a prospective cohort study (UPFRONT study, n = 1,151) of patients with mTBI admitted to the emergency department. Patients received questionnaires at 2 weeks and 3, 6, and 12 months after injury. RTW was divided into 3 levels: complete (cRTW), partial (pRTW), and no RTW.

Results:

Rates of cRTW increased from 34% at 2 weeks to 77% at 12 months after injury, pRTW varied from 8% to 16% throughout the year. Logistic regression (complete vs incomplete RTW) demonstrated that apart from previously identified predictors such as demographics (e.g., age and education) and injury characteristics (e.g., cause and severity of injury) and indicators of psychological distress, occupational factors were of influence on work resumption after 6 months (area under the curve [AUC] = 0.82), At 12 months, however, the model was based solely on the presence of extracranial injuries and indicators of maladaptation after injury (AUC = 0.81).

Conclusions:

RTW after mTBI is a gradual process, with varying levels of RTW throughout the first year after injury. Different predictors were relevant for short- vs long-term work resumption, with occupational factors influencing short-term RTW. However, for both short- and long-term RTW, posttraumatic complaints and signs of psychological distress early after injury were relevant predictors, allowing early identification of patients at risk for problematic work resumption.

Risk factors and outcomes associated with post-traumatic headache after mild traumatic brain injury

OBJECTIVES

To determine the prevalence and potential risk factors of acute and chronic post-traumatic headache (PTH) in patients with mild to moderate traumatic brain injury (TBI) in a prospective longitudinal observational multicentre study. Acute PTH (aPTH) is defined by new or worsening of pre-existing headache occurring within 7 days after trauma, whereas chronic PTH (cPTH) is defined as persisting aPTH >3 months after trauma. An additional goal was to study the impact of aPTH and cPTH in terms of return to work (RTW), anxiety and depression.

METHODS

This was a prospective observational study conducted between January 2013 and February 2014 in three trauma centres in the Netherlands. Patients aged 16 years and older with a GCS score of 9-15 on admission to the ED, with loss of consciousness and/or amnesia were prospectively enrolled. Follow-up questionnaires were completed at 2 weeks and 3 months after injury with the Head Injury Symptom Checklist, the Hospital Anxiety and Depression Scale and RTW scale.

RESULTS

In total, 628 patients were enrolled in the study, 469 completed the 2-week questionnaire (75%) at 2 weeks and 409 (65%) at 3 months. At 2 weeks, 238 (51%) had developed aPTH and at 3 months 95 (23%) had developed cPTH. Female gender, younger age, headache immediately at the ED and CT scan abnormalities increased the risk for aPTH. Risk factors for cPTH were female gender and headache at the ED. Patients with cPTH were less likely to have returned to work than those without cPTH (35% vs 14%, P=0.001). Patients with aPTH and cPTH more often report anxiety (20% and 28%, P=0.001) and depression (19% and 28%, P=0.001) after trauma in comparison with the group without PTH (10% anxiety and 8% depression).

CONCLUSIONS

PTH is an important health problem with a significant impact on long-term outcome of TBI patients. Several risk factors were identified, which can aid in early identification of subjects at risk for PTH.

[Addendum to the Dutch guideline for minor head/brain injury]

- After introduction of the Dutch guideline for 'Care for patients with minor head/brain injury' (LTH guideline) in 2010, the number of CT scans has increased. Some of these scans were for patients with only trivial trauma and may not have been necessary.- In addition, since this guideline was implemented, there have been changes in the use of anticoagulants and platelet aggregation inhibitors. Non-vitamin-K-dependent oral anticoagulants (NOACs) and platelet aggregation inhibitors, or combinations of these, are prescribed more often.- These two factors have led the Netherlands Society of Neurology to initiate a request for modification of the LTH guideline for adults in two ways: (a) identification of minimal or trivial trauma for which no CT scan is required and (b) inclusion of NOACs and platelet aggregation inhibitors, or combinations of these, in the guideline.

The juvenile head trauma syndrome: a trauma triggered migraine?

BACKGROUND

The underlying mechanism of the juvenile head trauma syndrome (JHTS) is still uncertain, but it has been suggested that there is a role in cortical spreading depression, a phenomenon that is assumed to be a part of the pathophysiology of migraine.

HYPOTHESIS

We postulate that children affected by the JHTS are more susceptible to cortical spreading depression, caused by a genetic etiology similar to genetic factors in migraine.

METHODS

Children with the JHTS were selected and evaluated retrospectively in an observational case-control study in two Dutch trauma centers in the period between January 2008 and July 2012.

RESULTS

We included 33 patients with the JHTS, who were accounted for approximately 2.5% of the total number (1,342) of children seen at the emergency department with a mild head trauma. The prevalence of migraine in cases compared with controls did not differ. The proportion of patients with a first-degree relative with migraine was significantly higher in cases compared with controls (odds ratio, 2.69; 95% confidence interval, 1.16-6.22; p = 0.010).

CONCLUSION

The JHTS is a relatively rare phenomenon, seen in approximately 2.5% of all children seen at the emergency department with mild brain injury. This study demonstrates a significant relationship between the JHTS and a positive history of migraine in first-degree relatives.

Periictal and interictal headache including migraine in Dutch patients with epilepsy: a cross-sectional study

As early as in 1898, it was noted that there was a need to find "a plausible explanation of the long recognized affinities of migraine and epilepsy". However, results of recent studies are clearly conflicting on this matter. In this cross-sectional study, we aimed to define the prevalence and characteristics of both seizure-related and interictal headaches in patients with epilepsy (5-75years) seeking help in the tertiary epilepsy clinic SEIN in Zwolle. Using a questionnaire, subjects were surveyed on the existence of headaches including characteristics, duration, severity, and accompanying symptoms. Furthermore, details on epilepsy were retrieved from medical records (e.g., syndrome, seizure frequency, and use of drugs). Diagnoses of migraine, tension-type headache, or unclassifiable headache were made based on criteria of the International Classification of Headache Disorders. Between March and December 2013, 29 children and 226 adults were evaluated, 73% of whom indicated having current headaches, which is significantly more often when compared with the general population (p<0.001). Forty-nine percent indicated having solely interictal headache, while 29% had solely seizure-related headaches and 22% had both. Migraine occurs significantly more often in people with epilepsy in comparison with the general population (p<0.001), and the occurrence of tension-type headaches conforms to results in the general population. These results show that current headaches are a significantly more frequent problem amongst people with epilepsy than in people without epilepsy. When comparing migraine prevalence, this is significantly higher in the population of patients with epilepsy.

[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.