[Genetics of tremor]. / Genetik des Tremors.

BACKGROUND: Tremor is a symptom of many diseases and can constitute a disease of its own: essential tremor. OBJECTIVE: The genetics of essential tremor and differential diagnosis of monogenic diseases with the symptom tremor. MATERIAL AND METHODS: Literature search and search of clinical genetics databases, e.g. OMIM, GeneReviews, MDSGene and the German Neurological Society (DGN) guidelines. RESULTS: The genetics of essential tremor remain unresolved in spite of large, adequately powered studies. Tremor is a symptom of differential diagnostic value in many movement disorders. A slight tremor might have been missed or not reported in many descriptions of movement disorders. CONCLUSION: Progress in the genetics of essential tremor probably requires a more detailed phenotyping allowing stratification into phenotypically defined subgroups. Tremor should always be included in the examination and description of movement disorders even if tremor is not a cardinal symptom. Tremor might be helpful in the differential diagnosis of hereditary dystonia, hereditary ataxia, spastic paraplegia and other movement disorders.

GABA(A) receptor- and GABA transporter polymorphisms and risk for essential tremor.

BACKGROUND: Clinical features and animal models of essential tremor (ET) suggest gamma-aminobutyric acid A receptor (GABA(A) R) subunits and GABA transporters as putative candidate genes. METHODS: A total of 503 ET cases and 818 controls were investigated for an association between polymorphisms in 15 GABA(A) R and four GABA transporter genes and ET. RESULTS: Nine nominally significant tagging SNPs (P values from 4.9×10(-2) to 5.2×10(-4) ) were found in the hypothesis generation stage. Five SNPs were followed up in a second verification stage but failed to reach significance. (P values from 0.30 to 0.77). DISCUSSION: In our samples, no evidence of association between GABA(A) R and GABA transporter genes with ET was detected. Further studies are necessary to clarify the role of these genes in ET.

The outer arterial wall layers are primarily affected in spontaneous cervical artery dissection.

OBJECTIVE: To evaluate the macroscopic and microscopic phenotype of the distal superficial temporal artery (STA) in patients with spontaneous cervical artery dissection (sCAD, n = 14). Arteries of accident victims, free of clinically apparent vascular disease, served as reference samples (n = 9). METHODS: Specimens of distal STA branches were obtained by biopsy or at autopsy. Their fine and ultrafine structure was documented by close-up photography of native STA branches, light microscopy, and electron microscopy in a case-control study. RESULTS: STA specimens from patients with sCAD revealed pathologic changes mainly in the adventitial and medial layers. In these areas, vacuolar degeneration and fissuring were associated with neoangiogenesis of capillaries and microscopic erythrocyte extravasation into the connective tissue. In addition, some specimens showed overt microhematomas close to the medial/adventitial border visible at low magnification. The reference arteries showed virtually no pathologic changes in the outer arterial layers. CONCLUSION: Bearing in mind that the STA is only a surrogate for the cervical arteries affected by sCAD, we propose the following pathogenetic model. We hypothesize that sCAD affects primarily the outer arterial layers. The process starts with degenerative changes at the medial-adventitial border associated with neoangiogenesis of capillary vessels branching from vasa vasorum in the adventitia. Leakage of neoangiogenetic capillaries releases blood cells into the connective tissue and leads to formation of microhematomas along the medial/adventitial border, as well as disintegration of the medial and adventitial texture. Microhematomas might then cause successive rupture of multiple neoangiogenetic capillaries and vasa vasorum, ultimately resulting in dissection.

Sensitivity of neurovascular ultrasound for the detection of spontaneous cervical artery dissection.

The reported sensitivity of neurovascular ultrasound (nUS) for detecting spontaneous cervical artery dissection (sCAD) varies from 80% to 96% in the internal carotid artery (ICA) and from 70% to 86% in the vertebral arteries (VA). The aim of this study was to assess the sensitivity of nUS compared to MRI of the neck and MR angiography for the detection of sCAD. Forty consecutive patients with sCAD proven by 1.5T MRI were investigated by nUS within 48 hours of admission. A total of 52 cases of sCAD were detected by MRI, equally distributed (n=26, 50%) in the ICA and VA territories. Two sCADs affecting the ICA (n=2, 8%) and two sCADs of the VA (n=2, 8%) had normal initial nUS findings. The sensitivity of nUS in detecting sCAD is high, about 92% for both vascular territories. However, intramural hematomas may be missed either when they are located outside the arterial segments directly visible by nUS or if they are too small to cause hemodynamically significant stenosis.

Assessment of skin extensibility and joint hypermobility in patients with spontaneous cervical artery dissection and Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome (EDS) is a hereditary connective tissue disorder. One important clinical characteristic of classical type EDS is skin hyperextensibility. Examination of clinical evidence and electron microscopic views of skin biopsies suggest that connective tissue abnormalities resembling very mild EDS are present in a sizable proportion of patients with spontaneous cervical artery dissection (sCAD). Manual assessment of skin extensibility is difficult. Therefore, non-invasive machine-aided measurement of skin extensibility was used and compared with manual assessment of skin extensibility and joint hyperextensibility. Patients with classical EDS, vascular-type EDS, sCAD and healthy patients were evaluated. Skin extensibility was measurably and palpably elevated in all patients with classical type EDS but not in sCAD patients or patients with vascular-type EDS compared to healthy control individuals. Our method is able to measure the increased skin extensibility in classical type EDS. Increased skin extensibility is not present in sCAD patients.

Morphometric analysis of collagen fibrils in skin of patients with spontaneous cervical artery dissection.

BACKGROUND AND AIM: The aetiopathogenesis of spontaneous cervical artery dissection (sCAD) is largely unknown. Electron microscopic (EM) examination of skin biopsies of patients with sCAD revealed very subtle pathological changes of dermal connective tissue in about half of these patients leading to the hypothesis of an underlying connective tissue disorder. However, connective tissue abnormalities did not allow clear discrimination between patients and controls in our hands. Therefore, we sought to establish an objective basis for the assessment of connective tissue abnormalities in patients with sCAD using standardised morphometric assessment of collagen fibrils. METHODS: In this study a blinded examination was performed of collagen in skin biopsies and it sought parameters which are able to discriminate between patients with sCAD and controls. Various morphometric parameters were compared between patients with sCAD (n = 20) and control subjects (n = 18). RESULTS: Previously described "flower-like" collagen fibrils in skin biopsies were extremely rare in patients and controls and did not discriminate between the groups. However, they were abundant in the skin biopsy of a patient with Ehlers-Danlos syndrome type III (EDSIII) used as a reference. Morphometric parameters such as collagen fibril diameter, fibril density and relative fibril area did not discriminate between patients and controls on an individual basis, but the mean diameter of collagen fibrils in the skin was lower in patients with sCAD compared with controls while fibril density was higher resulting in nearly equal fibril areas per unit of area (relative fibril area) comparing both groups as well as individuals. CONCLUSIONS: Blinded pathological and morphometric analysis of collagen fibres in skin biopsies was, in our hands, unable to discriminate reliably between patients with sCAD and controls on an individual basis but did show differences in collagen fibril morphometry on a group basis. Furthermore, systematic and blinded pathological studies of skin biopsies in patients with sCAD and controls are needed.

Association between single nucleotide polymorphisms in the lysyl oxidase-like 1 gene and spontaneous cervical artery dissection.

BACKGROUND: Spontaneous cervical artery dissection (sCAD) is a common cause of stroke in patients below 55 years. Dermal connective tissue abnormalities have been observed in up to 60% of patients. A chromosomal locus for connective tissue abnormalities associated with sCAD has been mapped to chromosome 15q24 to a candidate region containing the lysyl oxidase-like 1 gene (LOXL1). LOXL1 an excellent candidate susceptibility gene for non-familial sCAD was investigated by mutation analysis and a genetic association study. METHODS: We sequenced the whole coding region of the LOXL1 gene in 15 sCAD patients and performed a genetic association study in 157 sCAD patients using 12 single nucleotide polymorphisms (SNP). RESULTS: The SNP rs3825942 (Gly153Asp) showed marginal association with sCAD on an allele basis and in the dominant genetic model, and intronic SNP rs893817 under a recessive model only. None of the SNP haplotypes was associated with sCAD. CONCLUSIONS: Genetic variation in LOXL1 might play a role as a risk factor for sCAD.

Polyarterial clustered recurrence of cervical artery dissection seems to be the rule.

BACKGROUND: Spontaneous cervical artery dissection (sCAD) in multiple neck arteries (polyarterial sCAD) is traditionally thought to represent a monophasic disorder suggesting nearly simultaneous occurrence of the various intramural hematomas. Its incidence ranges from 10 to 28%. The recurrence rate of sCAD in general over up to 8.6 years has been recorded to be 0 to 8%. OBJECTIVE: To analyze more precisely the temporal and spatial neuroangiologic course of sCAD with particular focus on polyarterial manifestation. METHODS: We prospectively investigated 36 consecutive patients with sCAD unexceptionally proven by MR imaging at 1.5 T. We reinvestigated these patients by two follow-up MR examinations. The first follow-up MR examination was performed after a mean of 16 +/- 13 days, and the last MR study after a mean of 7 +/- 2 months after the initial diagnosis. RESULTS: Systematic data evaluation of the 36 patients revealed the following phenomena of sCAD: 1) seemingly simultaneous polyarterial sCAD on the initial MRI scan (n = 2; 6%); 2) recurrent sCAD in one or several initially uninvolved cervical arteries during follow-up (n = 9; 25%). These latter sCAD occurred as an early polyarterial recurrent event within 1 to 4 weeks in 7 patients (19%), and as a delayed polyarterial recurrent event within 5 to 7 months in 2 patients (6%). Under a spatial perspective, sCAD recurrence took place in one additional cervical artery in 5 patients (14%), or in more than one previously uninvolved cervical artery in 4 patients (11%). All patients except one with sCAD recurrence remained asymptomatic or had local symptoms only. One patient experienced a significant clinical deterioration due to ischemic stroke with acute impairment of cerebral hemodynamics. During follow-up, patients received transient oral anticoagulation for at least 6 months with subsequent acetylsalicylic acid (ASA). CONCLUSION: More often than previously thought, the recurrence of spontaneous cervical artery dissection (sCAD) involves multiple cervical arteries in sequence. sCAD recurrence frequently appears to cluster within the first 2 months after the index event, rather than occurring steadily over time. The prognosis of recurring sCAD appears benign, particularly in patients already receiving antithrombotic therapy.

Connective tissue and vascular phenotype in patients with cervical artery dissection.

BACKGROUND: Clinical observations and electron microscopic investigation of skin biopsies demonstrated connective tissue abnormalities in a sizeable proportion of patients with spontaneous cervical artery dissection (sCAD), suggesting an unknown connective tissue disorder as a risk factor for sCAD. OBJECTIVE: To evaluate in a case-control setting if patients with sCAD exhibit clinical signs indicative of a connective tissue disorder or show a vascular phenotype. METHODS: We investigated 43 consecutive patients with sCAD and 43 consecutive patients of similar age with ischemic stroke of other etiology. All patients underwent standardized MRI of the head and neck. The clinical investigation contained 25 items characteristic for connective tissue diseases such as hyperextensible skin, articular hypermobility, capillary fragility, and facial stigmata. A sum score counting all positive items was calculated. Additionally, the diameter of the common carotid artery (CCA) and vertebral artery (VA) and heart valve pathologies were assessed. RESULTS: Connective tissue sum scores did not differ between the sCAD group (mean 2.37 +/- 2.1, median 2) and the control group (mean 1.95 +/- 1.9, median 2, p = 0.34). One sCAD patient had osteogenesis imperfecta (2.3%) and exhibited the highest sum score of 8. The diameter of the CCA and VA and the prevalence of heart valve pathologies did not show any significant differences between groups. CONCLUSION: The connective tissue and vascular phenotype did not differ significantly between patients with spontaneous cervical artery dissection (sCAD) and control subjects with ischemic stroke of other etiology. These findings argue against a clinically apparent connective tissue disorder underlying sCAD. The prevalence of known connective tissue diseases in sCAD patients is low.

A distinctive case of fibromuscular dysplasia.

Fibromuscular dysplasia (FMD) is a rare, non-inflammatory angiopathy, which can affect the brain supplying arteries. Usually, the diagnosis is based on conventional and/or MR angiography. We present a patient with multisegmental stenoses of the internal carotid artery (ICA) where the diagnosis of FMD is based on an eye-catching ultrasound finding.

Mild mechanical traumas are possible risk factors for cervical artery dissection.

BACKGROUND AND PURPOSE: Cervical artery dissection (CAD) is a common cause of ischemic stroke in younger aged subjects. Retrospective studies suggest cervical manipulative therapy (CMT) and preceding infections as extrinsic risk factors for CAD. In a case-control study, we assessed a questionnaire with 7 mild mechanical traumas as potential trigger factors for CAD, including CMT and recent infections. PATIENTS AND METHODS: Forty-seven consecutive patients with CAD were compared with 47 consecutive patients of similar age with ischemic stroke due to etiologies other than CAD. Patients underwent a standardized face-to-face interview. We assessed head or neck pain and recent infection <7 days before symptom onset, as well as the following mechanical trigger factors <24 h and <7 days prior to symptom onset: (1) heavy lifting, (2) sexual intercourse, (3) mild direct or (4) indirect neck trauma, (5) jerky head movements, (6) sports activity, and (7) CMT. RESULTS: We found no association between any single one of the above risk factors and CAD. CMT (CAD, n = 10; non-CAD, n = 5) and recent infections (CAD, n = 18; non-CAD, n = 10) were more frequent in the CAD group but failed to reach significance. However, the cumulative analysis of all mechanical trigger factors revealed a significant association of mechanical risk factors as a whole in CAD <24 h prior to symptom onset (p = 0.01). CONCLUSION: Mild mechanical stress, including CMT, plays a role as possible trigger factor in the pathogenesis of CAD. CMT and recent infections alone failed to reach significance during the present investigation, presumably due to the relatively small sample size of the study cohort.

Evaluation of single nucleotide polymorphisms in the phosphodiesterase 4D gene (PDE4D) and their association with ischaemic stroke in a large German cohort.

Genetic fine mapping of the first locus identified for genetically complex forms of stroke, STRK1 (which has been mapped to chromosome 5q12 in Icelandic families), has identified the phosphodiesterase 4D gene (PDE4D) gene as a good candidate gene. Association analysis of single nucleotide polymorphisms (SNPs) in the PDE4D gene in an Icelandic stroke cohort demonstrated genetic association between six SNPs in the 5' region of PDE4D and ischaemic stroke. The present study aimed to test whether the same six SNPs in PDE4D were also associated with stroke in a large stroke cohort from northern Germany (stroke patients with acute completed ischaemic stroke: n = 1181; population based controls: n = 1569). None of the six SNPs showed significant association with ischaemic stroke in the whole stroke sample before and after adjustment for conventional stroke risk factors (age, sex, hypertension, diabetes, and hypercholesterolaemia). Haplotype analysis did also not reveal any significant association. Marginally positive statistical measures of association in the subgroup with cardioembolic stroke did not remain significant after correction for multiple testing. In conclusion, this study was unable to demonstrate an association between the six SNPs which had showed significant single marker association with stroke in the Icelandic stroke cohort and ischaemic stroke in a large German cohort.

Genetic variants of the NOTCH3 gene in migraine--a mutation analysis and association study.

Mutations in the NOTCH3 gene cause cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Exons 3 and 4 are mutation hotspots. Migraine is a clinical hallmark of CADASIL. The objective of this study was to investigate whether genetic variants in exons 3 and 4 of the NOTCH3 gene are associated with migraine. Exons 3 and 4 of the NOTCH3 were analysed for mutations and polymorphisms by direct DNA sequencing in 97 migraineurs and the same number of control individuals. No mutations in exons 3 and 4 of the NOTCH3 gene were found in 97 patients with migraine. However, association analysis revealed significant association of the single nucleotide polymorphism (SNP) rs1043994 with migraine.

Negative ultrasound findings in patients with cervical artery dissection. Negative ultrasound in CAD.

BACKGROUND: Cervical artery dissection (CAD) is a common cause of ischemic stroke in the younger age group. Modern imaging techniques allow the depiction of the mural hematoma, even in CADs with only subtle vessel alterations. The aim of this retrospective study was (1) to characterize the angiological features in CAD and (2) to determine the frequency of initially normal ultrasonography (US) findings. METHODS: 86 patients aged 44 +/- 11 years with CAD of the internal carotid (ICA), (n = 55) or the vertebral artery (VA), (n = 31), admitted to our hospital within 8 days (mean 1.6 days) of symptom onset, were included. CAD was confirmed either by CT-angiography, MRI of the neck, MR-angiography or digital substraction angiography (DSA) and was compared with the results of the initial as well as repeated US examinations of the arteries supplying the brain. RESULTS: In 75 patients (81.2 %) signs of vessel stenosis or occlusion were found while 11 patients (12.8%) with CAD of the ICA (n = 9) and the VA (n = 2) had normal US findings. The site of dissection in the US negative patients was highly variable without a predilection site. In 2 of 7 patients with repeated US examinations, complete vessel occlusion was found on follow-up, while in 5 patients again normal results were found. In four patients, there were changing findings in two alternative confirming imaging methods (MRI/DSA, CT/MRI) and in one patient conflicting findings (CT/MRI). Brain infarctions had occurred in 7 of the initially sonographically normal patients while the other 4 had suffered from transient (n = 2) or local (n = 2) symptoms only. CONCLUSION: Approximately 1 out of 8 patients with subsequently proven CAD has negative initial neurovascular US findings despite comprehensive examination. In patients with suspected CAD and negative US examination, repeated US examinations and further diagnostic imaging, especially MRI is necessary.

[Incidence of cerebral ischemia in patients with suspected cervical artery dissection: first results of a prospective study]. / Inzidenz zerebraler Ischämien bei Patienten mit dem Verdacht einer spontanen Dissektion der extrakraniellen Arterien: Erste Ergebnisse einer prospektiven Studie.

PURPOSE: Aim of this prospective study was to investigate the incidence of spontaneous cervical artery dissection (sCAD) and cerebral ischemia in patients with suspected sCAD by using a combined head-neck MR-imaging protocol. MATERIALS AND METHODS: 51 consecutive patients (24 m, 27 f, mean age 39.5 years, range 18 - 55 yrs) admitted to our stroke unit with suspected sCAD according to clinical criteria and age < 55 years underwent a combined head and neck MR examination within 24 hours of admission (Gyroscan Intera 1.5 T, Philips). Head MRI included ax FLAIR, ax T (1), ax DWI and TOF angiography (imaging time 12 min). Neck MRI consisted of ax T1w-TSE, T2w-TSE, contrast enhanced T1w-TSE and CE-MRA (imaging time 17 min). Three radiologists assessed both studies in consensus with regard to the presence of sCAD and acute ischemia. RESULTS: One patient had to be excluded because of motion artefacts. In 17 of 50 patients sCAD was diagnosed, and in 20 of 50 patients cerebral ischemia. In 5 patients cerebral ischemia was caused by sCAD. CONCLUSION: The proposed combined MR protocol allows imaging work-up of patients with suspected sCAD within approximately 30 min, resulting in conclusive information about the status of the extracranial vasculature and the presence of ischemia. The high incidence of patients with definite sCAD and the low incidence of cerebral ischemia indicates the necessity of an early definite diagnosis in order to start timely anticoagulation to prevent development of stroke.

Generalized arteriopathy in patients with cervical artery dissection.

OBJECTIVE: To make an ultrastructural comparison of superficial temporal artery (STA) biopsy specimens from patients with spontaneous cervical artery dissection (sCAD) and controls. METHODS: The authors used light microscopic examination of semithin sections and electron microscopic examination of ultrathin sections of STA biopsy specimens from patients with sCAD and controls. RESULTS: STA biopsy specimens from patients with sCAD taken around the time of the dissection showed a zone of connective tissue weakening with fissuring at the junction between the tunica media (TM) and the tunica adventitia (TA) in seven of nine specimens and erythrocyte infiltration in eight of nine specimens but in none of the control specimens. Light microscopy demonstrated transparent circular spots that, on electron microscopy, turned out to represent erythrocytes and other cellular components at different stages of degradation. Occasionally, scattered immune cells were found in specimens from patients with sCAD. In addition, smooth muscle cells of the synthetic phenotype, some of them showing extensive vacuolation were more common in the TM of STA biopsy specimens from patients with sCAD than in control specimens. CONCLUSIONS: Signs of tissue weakening along the TM/TA junction in STA biopsy specimens of patients with sCAD but not in controls suggest the presence of a generalized arteriopathy leading to impairment of the stability of the arterial wall in patients with sCAD. Limiting factors of the study are that some control biopsies were obtained from autopsies and that the anticoagulation status of patients and controls were not completely comparable.