Diseases associated with subsequent peritonsillar abscess: a case-control-study from ENT practices in Germany.

OBJECTIVE: Peritonsillar abscess (PTA) is the most common deep soft tissue infection necessitating surgical intervention in the head and neck region. Potential causes include infections of the palatine tonsils, palatine glands, or branchiogenic rudiments ("acute tonsillitis hypothesis" vs. "Weber's gland hypothesis"). Understanding the currently still unknown predominant cause is crucial for guiding therapeutic strategies, such as abscess tonsillectomy versus incision and drainage alone. This study aims to investigate the pre-diagnoses associated with subsequent PTA using a nationally representative practice database in Germany. METHODS: Data were collected from 195 ENT practices across Germany utilizing the nationally representative practice database IQVIA™ Disease Analyzer. Included were patients aged 18 years and older with a first diagnosis of PTA (index date) between January 2005 and December 2022 and a minimum observation period of 12 months preceding the index date. These patients were matched (1:5) with controls without PTA, based on age, sex, and index year. Frequencies of prior diagnoses coded according to ICD-10 in the 12 months preceding the index date were computed. The association between prior diagnoses and PTA was evaluated using multivariable logistic regression (MLR) and sensitivity analysis (SA). RESULTS: A total of 5,325 cases were compared with 26,725 controls in the multivariable logistic regression (MLR) analysis, and 16,251 cases were compared with 81,255 controls in the sensitivity analysis (SA). Mean age was 45.3 ± 18.3 years (MLR) and 41.9 ± 16.7 years (SA). The proportion of female patients was 51.8% (MLR) and 46.9% (SA), respectively. MLR showed the strongest associations with PTA for the prior diagnoses of "acute tonsillitis" (odds ratio, OR: 6.71; 95% CI: 5.81-7.74), "chronic tonsillitis" (OR: 2.00; 95% CI: 1.58-2.52), and "acute pharyngitis" (OR: 1.74; 95% CI: 1.50-2.03). SA similarly indicated the strongest associations with PTA for the prior diagnoses of "acute tonsillitis" (OR: 5.02; 95% CI: 4.60-5.47), "chronic tonsillitis" (OR: 1.87; 95% CI: 1.64-2.12), and "acute pharyngitis" (OR: 1.27; 95% CI: 1.14-1.41). CONCLUSION: The most prevalent prior diagnosis associated with PTA was acute tonsillitis, followed by chronic tonsillitis and acute pharyngitis. The association with acute pharyngitis suggests possible non-tonsillogenic causes. Other specific causes of PTA, such as inflammation of the palatine gland or branchiogenic remnants, are not captured by the ICD system or the database utilized in this study.

Systemic therapy in children and adolescents with mental disorders: a systematic review and meta-analysis.

BACKGROUND: Systemic therapy (ST) is a psychotherapeutic intervention in complex human systems (both psychological and interpersonal). Cognitive behavioural therapy (CBT) is an established treatment for children and adolescents with mental disorders. As methodologically rigorous systematic reviews on ST in this population are lacking, we conducted a systematic review and meta-analysis to compare the benefit and harm of ST (and ST as an add-on to CBT) with CBT in children and adolescents with mental disorders. METHODS: We searched MEDLINE, Embase, PsycINFO and other sources for randomised controlled trials in 14 mental disorder classes for the above comparisons in respect of effects on patient-relevant outcomes (search date: 7/2022). Where possible, meta-analyses were performed and results were graded into 3 different evidence categories: "proof", "indication", or "hint" (or none of these categories). PRISMA standards were followed. RESULTS: Fifteen studies in 5 mental disorder classes with usable data were identified. 2079 patients (mean age: 10 to 19 years) were analysed. 12/15 studies and 29/30 outcomes showed a high risk of bias. In 2 classes, statistically significant and clinically relevant effects in favour of ST were found, supporting the conclusion of a hint of greater benefit of ST for mental and behavioural disorders due to psychoactive substance use and of ST as an add-on to CBT for obsessive-compulsive disorders. In 2 other classes (eating disorders; hyperkinetic disorders), there was no evidence of greater benefit or harm of ST. For affective disorders, a statistically significant effect to the disadvantage of ST was found for 1 outcome, supporting the conclusion of a hint of lesser benefit of ST. CONCLUSIONS: Our results show a hint of greater benefit of ST (or ST as an add-on to CBT) compared with CBT for 2 mental disorder classes in children and adolescents (mental and behavioural disorders due to psychoactive substance use, obsessive compulsive disorders). Given the importance of CBT as a control intervention, ST can therefore be considered a beneficial treatment option for children and adolescents with certain mental disorders. Limitations include an overall high risk of bias of studies and outcomes and a lack of data for several disorders.

Incidence of Inner Ear Disorders in Various Forms of Acute Otitis Media in ENT Practices in Germany.

OBJECTIVE: The aim of this study was to determine the incidence of inner ear involvement in various forms of acute otitis media (AOM) in ear, nose, and throat (ENT) practices in Germany. METHODS: Patients who had been diagnosed with various forms of AOM in the years 2010 to 2017 were enrolled in the study from a nationwide, representative practice database (Disease Analyzer, IQVIA). In these patients, the incidence of simultaneous or subsequent inner ear disorders (IED) was determined within 7 days and within 12 months from the date of an AOM diagnosis. RESULTS: A total of 286 186 patients with AOM were enrolled. The most frequent diagnoses were "nonsuppurative otitis media, unspecified" (47.6%) and "otitis media, unspecified" (39.0%). The diagnoses of hemorrhagic bullous myringitis (BM) or influenza-induced AOM were very rarely found in the database. The highest incidence of IED after 7 days and 12 months was found in "nonsuppurative otitis media, unspecified" (7.7% and 15.9%, respectively), followed by "otitis media, unspecified" (5.6% and 13.5%, respectively). The incidences of the most frequent IED "hearing loss, unspecified" and "sensorineural hearing loss, unspecified" increased proportionally with increasing patient age, while the rare diagnoses of "labyrinthitis" and "ototoxic hearing loss" were evenly distributed among the age groups. CONCLUSION: In ENT practices in Germany, both various forms of AOM, as well as simultaneous or subsequent IED, are mostly being coded in an unspecific way, while specific forms such as hemorrhagic BM, influenza-induced AOM, and labyrinthitis are coded very rarely. Older patients have a higher risk of IED in AOM. A visit due to AOM seems to be a regular occasion for the initial diagnosis of hearing impairment in the elderly individuals. The highest risk of IED was found in nonsuppurative AOM.

Assessment of work-related hand and elbow workloads using measurement-based TLV for HAL.

Direct-measurement-based methods for assessing workloads of the hand or elbow in the field are rare. Aim of the study was to develop such a method based on the Threshold Limit Value for Hand Activity Level (TLV for HAL). Hence, HAL was quantified using kinematic data (mean power frequencies, angular velocities and micro-pauses) and combined with electromyographic data (root-mean-square values) in order to generate a measurement-based TLV for HAL (mTLV for HAL). The multi-sensor system CUELA including inertial sensors, potentiometers and a 4-channel surface electromyography module was used. For wrist and elbow regions, associations between mTLV for HAL and disorders/complaints (quantified by odds ratios (OR [95%-confidence interval])) were tested exploratively within a cross-sectional field study with 500 participants. Higher workloads were frequently significantly associated with arthrosis of distal joints (9.23 [3.29-25.87]), wrist complaints (2.89 [1.63-5.11]) or elbow complaints (1.99 [1.08-3.67]). The new method could extend previous application possibilities.

Incidence and Risk of Various Disorders of the External Ear in Patients With Hearing Aids Treated in ENT Practices in Germany.

OBJECTIVE: The aim of the study was to investigate the relationship between the presence of a hearing aid (HA) and the occurrence of various disorders of the external ear, using data from ear, nose, and throat (ENT) practices in Germany from a nationwide, representative practice database. METHODS: In the period between 2012 and 2016, the incidences of disorders of the external ear (ICD-10 groups H60 and H61) in patients with HA prescriptions were compared retrospectively with a control group without HA prescriptions (1:1 matching). RESULTS: A total of 20,127 patients with HA prescriptions were compared with 20,127 controls. The highest 12-month incidences (HA vs. controls) were determined for "Impacted cerumen" (H61.2) (16.5% vs. 4.2%), "Unspecified otitis externa" (H60.9) (2.6% vs. 1.2%) and 'Acute noninfective otitis externa' (H60.5) (2.3% vs. 0.7%). The most significant risk increases for HA wearers were found for "Abscess of external ear' (H60.0, OR 10.03), "Other otitis externa' (H60.8, OR 6.00), and "Impacted cerumen' (H61.2, OR 4.55). A smaller risk increase was found for "Cholesteatoma of external ear' (H60.4, OR 2.26), among others. CONCLUSION: In HA wearers, the risk of developing almost all of the diagnoses reviewed is significantly increased, especially for external auditory canal (EAC) furuncle, chronic otitis externa, and impacted cerumen. This study provides the first epidemiological evidence for HA as a risk factor for the rare EAC cholesteatoma.

Demographic data and seasonal variation in peripheral vestibular disorders in ENT practices in Germany.

AIM: The aim of this study was to analyze the demographic data pertaining to and seasonal variation in specific vestibular disorders in ear, nose, and throat (ENT) practices in Germany based on data from a representative nationwide practice database. METHOD: The study sample included patients from 116 ENT practices in Germany who received an initial diagnosis (ICD-10 code) of Meniere's disease (MD, H81.0), benign paroxysmal positioning vertigo (BPPV, H81.1), or vestibular neuronitis (VN, H81.2) between January 2014 and December 2016. Collected parameters included age, sex, and month of diagnosis. Seasonal variation was analyzed for younger vs. older patients (≤50 vs. >50 years of age). Two univariate Poisson regression models were fitted to estimate the association between the month of diagnosis and the number of diagnosed patients per practice. RESULTS: A total of 20,720 patients were available for analysis. The average case numbers for MD, BPPV, and VN were 0.8 patients, 2.7 patients, and 1.5 patients per practice per month, respectively. The mean ages of female vs. male patients were 55 and 56 years (MD), 59 and 60 years (BPPV), and 58 and 57 years (VN), respectively. The proportions of female patients with these diagnoses were 62%, 70%, and 61%, respectively. All diagnoses were evenly distributed throughout the years in all age groups. No seasonal variation was observed. CONCLUSIONS: The demographic data of MD and BPPV patients are comparable to those found by previous large-scale epidemiologic studies. However, no seasonal variation was demonstrated for any vestibular disorder in this large sample.

Quantitative Measures of Physical Risk Factors Associated with Work-Related Musculoskeletal Disorders of the Elbow: A Systematic Review.

BACKGROUND: Work-related musculoskeletal disorders at the elbow are a common health problem, which highly impacts workers' well-being and performance. Besides existing qualitative information, there is a clear lack of quantitative information of physical risk factors associated with specific disorders at the elbow (SDEs). OBJECTIVE: To provide evidence-based quantitative measures of physical risk factors associated with SDEs. METHODS: Studies were searched from 2007 to 2017 in Medline, EMBASE, and Cochrane Work. The identified risk factors were grouped in main- and sub-categories of exposure using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework for rating evidence. RESULTS: 133 different risk-factor specifications were identified in 10/524 articles and were grouped into 5 main- and 16 sub-categories of exposure. The risk factors were significantly associated with lateral epicondylitis, medial epicondylitis, or ulnar neuropathy. Significant risk factors such as wrist angular velocity (5°/s, with increasing prevalence ratio of 0.10%/(°/s), or forearm supination (≥45° and ≥5% of time combined with forceful lifting) were found. CONCLUSIONS: This review delivers a categorization of work-related physical risk-factor specifications for SDEs with a special focus on quantitative measures, ranked for evidence. These results may build the base for developing risk assessment methods and prospective preventive measures.

Reimbursement Pathways for New Diabetes Technologies in Europe: Top-Down Versus Bottom-Up.

Reimbursement by payers (policy makers and budget holders) is critical for the uptake and use of new diabetes technologies. The purpose of this article is to describe the different reimbursement pathways that exist for new diabetes technologies in five selected European countries using examples of recent reimbursement decisions. Countries can be grouped into one of three categories: "top-down" (where reimbursement decisions are usually made by policy makers, eg, France), "bottom-up" (where reimbursement decisions are usually made by budget holders, eg, Italy and Spain) and "mixed" (where reimbursement decisions can be made by both policy makers and budget holders, eg, Germany and England). Whatever category a specific country falls into will have different implications from a market access perspective.

Association of laryngeal cancer with vocal cord leukoplakia and associated risk factors in 1,184 patients diagnosed in otorhinolaryngology practices in Germany.

The aim of the present study was to analyze the association between laryngeal cancer and vocal cord leukoplakia in a large nationwide practice database. The study sample included 1,184 patients aged 18-90 years from 113 otorhinolaryngology practices in Germany who were diagnosed with vocal cord leukoplakia between 2007 and 2014. The rates of laryngeal cancer diagnosis within 5 years and the associated risk factors were analyzed. Within 6 months of initial diagnosis of vocal cord leukoplakia, 11% of the patients were diagnosed with laryngeal cancer. Between 7 months and 5 years after the diagnosis of leukoplakia, laryngeal cancer was diagnosed in 7.6% of the patients. Overall, within 5 years of leukoplakia diagnosis, 18.6% of the patients were diagnosed with laryngeal cancer (26.1% of men and 6.3% of women; P<0.001). Moreover, 31.3% of patients aged >65 years, 16.1% of patients aged 50-65 years and 7.6% of patients aged <50 years were diagnosed with laryngeal cancer (P<0.001). Patients aged >65 and those aged 50-65 years had a higher risk of being diagnosed with laryngeal cancer [odds ratio (OR)=4.90 and 2.55, respectively]. Furthermore, the risk of being diagnosed with laryngeal cancer was higher in men compared with that in women (OR=4.09). In the present real-world analysis, the rate of laryngeal cancer underlying vocal cord leukoplakia at first diagnosis appeared to be higher compared with the secondary malignant transformation rate occurring later during the course of the disease. Risk factors for laryngeal cancer included advanced age and male sex.

Diagnoses of Dizziness- and Vertigo-related Disorders in ENT Practices in Germany.

AIM: The aim of this study was to analyze the prevalence of dizziness- and vertigo-related diagnoses in ear, nose, and throat (ENT) practices in Germany and the associated demographic characteristics based on data from a representative nationwide practice database. METHOD: The study sample included patients from 138 ENT practices in Germany who received dizziness- and vertigorelated diagnoses (ICD-10 code) between January 2012 and December 2015. Collected parameters included age, sex, insurance status, prescribed medication (anatomical therapeutic chemical [ATC] class), and referrals to other specialists and hospitals. RESULTS: A total of 107,458 patients were available for analysis. Most common diagnoses were "dizziness and giddiness" (67.7%), "benign paroxysmal vertigo" (10.2%) and "disorder of vestibular function, unspecified" (7.2%). Referrals and admissions were made in 12.8%, mostly to radiologists (7.7%), followed by neurologists (3.7%), and hospitals (1.4%). Most referrals were made for unspecific diagnoses and for "vestibular neuronitis." The rate of medical prescriptions was 37.3%, with the most common prescription being for antivertigo preparations. CONCLUSIONS: Dizziness- and vertigo-related disorders are frequently diagnosed in ENT practices in Germany. The majority of these diagnoses are unspecific and lead to an increased rate of referrals and hospital admissions. The medical prescription rate, especially of antivertigo preparations, was high, even among patients with benign paroxysmal positioning vertigo. This study reflects a mostly pragmatic approach to a complex diagnostic and therapeutic challenge in daily ENT practice as well as the limited ability of the ICD-10 system to classify the underlying etiology.

Seasonal Variation of Epistaxis in Germany.

AIM: The goal of the present study was to analyze the seasonal variation of epistaxis in ear, nose, and throat (ENT) practices in Germany in 2016. METHODS: The present study sample included patients who received a first epistaxis diagnosis from physicians in 114 ENT practices in Germany between January 2016 and December 2016. The number of epistaxis patients per practice was calculated for each month. A logistic regression model, adjusted for age and sex, was used to calculate the association between epistaxis diagnosis and the month. RESULTS: The authors found a total of 15,523 patients with epistaxis in 114 ENT practices. Of these patients, 55.9% were men and the mean age was 47.8 ±â€Š27.6 years. The highest number of epistaxis patients was found in February (14.89 patients per practice) and the lowest in August (7.22 patients per practice). The age- and sex-adjusted risk of epistaxis was significantly higher in the months of February (OR = 1.32), March (OR = 1.37), April (OR = 1.34), May (OR = 1.35), and December (OR = 1.33) compared with August. CONCLUSIONS: The presentation of patients with epistaxis at German ENT practices shows a marked seasonal variation with a low in the summer, an increase in fall and winter, and a peak in February, March, and April.

Current healthcare pathways in the treatment of rhinosinusitis in Germany.

BACKGROUND: In the outpatient setting in Germany, patients with rhinosinusitis usually present at general practices (GP) or ear, nose, and throat practices (ENT) for initial diagnosis and treatment. OBJECTIVES: The aim of this study was to analyze the referral patterns of rhinosinusitis patients in GPs and ENT practices in Germany, with respect to existing recommendations. MATERIAL AND METHODS: The study sample included patients from 940 GP and 106 ENT practices from Disease Analyzer database (IQVIA) who received an acute sinusitis (AS) or chronic sinusitis (CS), or nasal polyp (NP) in 2015. RESULTS: The total numbers of patients in GP versus ENT practices were 24,648 versus 12,095 (AS), 26,768 versus 19,826 (CS), and 516 versus 1773 patients (NP). Referrals to ENT practices were made by GP in 12.3% (AS), 14.8% (CS), and 40.5% (NP). The percentages of patients in GP versus ENT practices with subsequent hospital admissions were 6.9 versus 3.3% (AS), 6.3 versus 6.5% (CS), and 9.5 versus 13.8% (NP), respectively. CONCLUSIONS: Although 40% of patients with NP who consult GPs are referred to ENT practices, it remains unclear how the other 60% are being treated. The hospital admission rates of patients with CS as well as of patients with NP were found to be surprisingly low.

Intracranial Nasal Dermoid Sinus Cyst: Transnasal Endoscopic Resection by Open Rhinoplasty Approach, With Intraoperative Video.

Nasal dermoid sinus cysts are rare congenital lesions that may lead to recurrent soft tissue infections and severe intracranial complications. In case of an intracranial extension, the traditional surgical approach includes a frontal craniotomy with significant morbidity. As a less invasive alternative, a transnasal endoscopic approach has been recommended.This report describes the transnasal endoscopic resection of an intracranial nasal dermoid sinus cyst via an open rhinoplasty approach, which achieved a wide surgical exposure with minimal invasivity and ideal aesthetic results. An intraoperative video demonstrates this combination of techniques in this rare skull base/intracranial pathology.

The Evidence Value Matrix for Diagnostic Imaging.

Evidence and value are independent factors that together affect the adoption of diagnostic imaging. For example, noncoverage decisions by reimbursement authorities can be justified by a lack of evidence and/or value. To create transparency and a common understanding among various stakeholders, we have proposed a two-dimensional matrix that allows classification of imaging devices into three distinct categories based on the available evidence and value: "question marks" (low value demonstrated in studies of any evidence level), "candidates" (high value demonstrated in retrospective case-control studies and smaller case series), and "stars" (high value demonstrated in large prospective cohort studies or, preferably, randomized controlled trials). We use several examples to illustrate the application of our matrix. A major benefit of the matrix includes the development of specific strategies for evidence and value generation. High-evidence/low-value studies are expensive and unlikely to convince decision makers, given the uncertainty of the impact on patient management and outcomes. Developing question marks into candidates first and then into stars will often be quicker and less expensive ("success sequence"). Only this more sophisticated and objective approach can justify the additional funding necessary to generate the evidence base to inform reimbursement by payers and adoption by providers.

Compact stabilized semiconductor laser for frequency metrology.

We report on the development of a frequency modulatable 795 nm semiconductor laser based on self-injection locking to a high-quality-factor whispering-gallery-mode microresonator. The laser is characterized by residual amplitude modulation below -80 dB and frequency noise better than 300 Hz/Hz(1/2) at offset frequencies ranging from 100 Hz to 10 MHz. The frequency modulation speed and span of the laser exceed 1 MHz and 4 GHz, respectively. Locking of the laser to the Doppler-free saturated absorption resonance of the (87)Rb D1 line is demonstrated and relative frequency stability better than 10(-12) is measured for integration time spanning from 1 s to 1 day. The architecture demonstrated in this study is suitable for the realization of frequency modulatable lasers at any wavelength.

Hearing threshold estimation by auditory steady-state responses with narrow-band chirps and adaptive stimulus patterns: implementation in clinical routine.

Objective hearing threshold estimation by auditory steady-state responses (ASSR) can be accelerated by the use of narrow-band chirps and adaptive stimulus patterns. This modification has been examined in only a few clinical studies. In this study, clinical data is validated and extended, and the applicability of the method in audiological diagnostics routine is examined. In 60 patients (normal hearing and hearing impaired), ASSR and pure tone audiometry (PTA) thresholds were compared. ASSR were evoked by binaural multi-frequent narrow-band chirps with adaptive stimulus patterns. The precision and required testing time for hearing threshold estimation were determined. The average differences between ASSR and PTA thresholds were 18, 12, 17 and 19 dB for normal hearing (PTA ≤ 20 dB) and 5, 9, 9 and 11 dB for hearing impaired (PTA > 20 dB) at the frequencies of 500, 1,000, 2,000 and 4,000 Hz, respectively, and the differences were significant in all frequencies with the exception of 1 kHz. Correlation coefficients between ASSR and PTA thresholds were 0.36, 0.47, 0.54 and 0.51 for normal hearing and 0.73, 0.74, 0.72 and 0.71 for hearing impaired at 500, 1,000, 2,000 and 4,000 Hz, respectively. Mean ASSR testing time was 33 ± 8 min. In conclusion, auditory steady-state responses with narrow-band-chirps and adaptive stimulus patterns is an efficient method for objective frequency-specific hearing threshold estimation. Precision of threshold estimation is most limited for slighter hearing loss at 500 Hz. The required testing time is acceptable for the application in everyday clinical routine.

Generation of a coherent near-infrared Kerr frequency comb in a monolithic microresonator with normal GVD.

We demonstrate experimentally, and describe theoretically, generation of a wide, fundamentally phase-locked Kerr frequency comb in a nonlinear resonator with a normal group velocity dispersion (GVD). A magnesium fluoride whispering-gallery mode resonator characterized with 10 GHz free spectral range and pumped either at 780 or 795 nm is used in the experiment. The envelope of the observed frequency comb differs significantly from the Kerr frequency comb spectra reported previously. We show via numerical simulation that, while the frequency comb does not correspond to generation of short optical pulses, the relative phase of the generated harmonics are fixed.

Measurement of stressful postures during daily activities: An observational study with older people.

This study measured the postures of older people during cooking and laundry. A sample of men and women aged 75+ years (n=27) was recruited and observed in a home-like environment. Postures were recorded with a measurement system in an objective and detailed manner. The participants were videotaped to be able to see where 'critical' postures occurred, as defined by a trunk inclination of ≥60°. Analysis of data was facilitated by specially developed software. Critical postures accounted for 3% of cooking and 10% of laundry, occurring primarily during retrieving from and putting in lower cabinets, the refrigerator, laundry basket or washing machine as well as disposing into the waste bin. These tasks involve a great variation in postural changes and pose a particular risk to older people. The results suggest that the use of stressful postures may decrease efficiency and increase fatigue, eventually leading to difficulties with daily activities. The specific tasks identified during which critical postures occurred should be targeted by designers in order to improve the activities. A few examples are given of how better design can reduce or eliminate some of the postural constraints.

A systematic review of the worldwide prevalence and incidence of Parkinson's disease.

BACKGROUND: A number of epidemiologic studies of Parkinson 's disease (PD) have been conducted worldwide over the years. Although every study reported the rise in prevalence and incidence rate of PD with the increasing age, the overall estimates were different across countries. The variation in reported data may partly be contributed by case ascertainment, case finding method, data collection, and most importantly different population structures. OBJECTIVE: Systematically review prevalence and incidence of PD and find the causes of variation in the results. MATERIAL AND METHOD: A literature search was conducted on Medline and EMBASE for studies worldwide investigating the prevalence and incidence of PD and included all adults, English and publication between 1965 and January 2010. The primary search of both databases yielded 5,330 results. After screening topics and abstracts, 168 relevant abstracts were tagged and saved for more thorough perusal. Ultimately, 40 papers were selected for review after applying the pre-specified inclusion criteria RESULTS: The worldwide prevalence of PD varies widely. One reason for the variation in prevalence estimates could be due to the differences in survival across countries. The use of epidemiological studies using medical records could be another reason for the variation in disease frequency. CONCLUSION: PD is common in the elderly. A number of descriptive epidemiologic studies have been conducted worldwide. Comparing the incidence and prevalence of Parkinson's disease is difficult.