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Dive into the research topics where Okan Dogu is active.

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Featured researches published by Okan Dogu.


Neurology | 2003

Unexpectedly low prevalence and unusual characteristics of RLS in Mersin, Turkey

Serhan Sevim; Okan Dogu; Handan Camdeviren; Resul Bugdayci; Tayyar Sasmaz; Hakan Kaleagasi; Mihriban Aral; İlter Helvacı

Objective: To determine the prevalence, risk factors, and clinical presentation of restless legs syndrome (RLS) in a Turkish population. Methods: A face-to-face, population-based epidemiologic survey was conducted. Multistep, stratified, cluster, and systematic samplings were used. A total of 3,234 adults were interviewed. Results: Of the 3,234 participants, 103 (3.19%) experienced RLS. This prevalence rate is lower than those of other epidemiologic studies conducted among European and North American populations. RLS was found to be more common among women, cigarette smokers, and individuals residing in high altitudes. The self-reported mental and general health status of patients was worse than in the control subjects. The prevalence of RLS did not differ by age or body mass index. Conclusion: The discrepancy in RLS prevalence studies (including the authors’) suggests that prevalence varies among different races, thus supporting a genetic predisposition.


Neurology | 2003

Prevalence of essential tremor Door-to-door neurologic exams in Mersin Province, Turkey

Okan Dogu; Serhan Sevim; Handan Camdeviren; Tayyar Sasmaz; Resul Bugdayci; Mihriban Aral; Hakan Kaleagasi; S. Un; Elan D. Louis

Estimates of the prevalence of essential tremor (ET) are probably low because screening questionnaires have been used. The authors estimated the prevalence of ET in Mersin Province, Turkey, in 2,253 individuals aged ≥40 years, all of whom were examined by study neurologists. There were 89 ET cases (prevalence = 4.0%, 95% CI = 3.2 to 4.8%). The prevalence of ET may be higher than previously estimated. This is important when defining the extent of the health care problem.


Journal of Neurology, Neurosurgery, and Psychiatry | 2004

Correlation of anxiety and depression symptoms in patients with restless legs syndrome: a population based survey

Serhan Sevim; Okan Dogu; Hakan Kaleagasi; Mihriban Aral; O Metin; Handan Camdeviren

Background and objectives: Restless legs syndrome (RLS) is an important and common cause of insomnia, and previous studies indicate that psychiatric wellbeing may be impaired among RLS patients. We aimed to investigate the interaction between anxiety/depression and RLS in a population based survey. Methods: Data were drawn from the Mersin University Neuro-Epidemiology Project, a representative community sample of adults aged over 17 years residing in Mersin (n = 3234). Subjects found to be positive for RLS (n = 103) were evaluated for symptoms of anxiety and depression using the Hamilton Anxiety and Depression Scales and compared with the same number of contemporaneous control subjects. Results: Significantly greater anxiety and depression symptoms were observed among patients with RLS than in the control subjects. Our data also seem to provide initial evidence of a correlation between the severity of RLS and of anxiety and depression symptoms (r = 0.21, p = 0.03 and r = 0.201, p = 0.04 respectively). Conclusions: Assessment of psychiatric status of RLS patients can be helpful and sometimes necessary to determine additional features and treatment strategies of this bothering condition. Further studies are needed to replicate our findings using longitudinal data.


Clinical Neurology and Neurosurgery | 2004

Ultrasound-guided versus 'blind' intraparotid injections of botulinum toxin-A for the treatment of sialorrhoea in patients with Parkinson's disease.

Okan Dogu; Demir Apaydin; Serhan Sevim; Derya Talas; Mihriban Aral

OBJECTIVE To investigate the efficacy and safety of intraparotid botulinum toxin-A (BTX-A) injections into parotid gland using ultrasound-guided versus nonguided techniques for the treatment of sialorrhoea in patients with Parkinsons disease (PD). METHODS 15 patients with PD and sialorrhoea were included and divided into two groups. Group A patients (n=8) were injected with BTX-A using ultrasound guidance. Group B patients (n=7) were injected with BTX-A without ultrasound guidance. Saliva secretion was assessed quantitatively at baseline and at weeks 1, 4, and 12. Patients and/or caregivers also assessed the saliva secretion using visual analog scale (VAS). RESULTS All patients except one reported subjective improvement in sialorrhoea at the first week. Group A patients showed significantly higher rate of saliva reduction at the first week, whereas in Group B the reduction was not statistically significant from baseline at the first week (P>0.05). Comparisons of quantitative saliva assessments at each follow-up visit also showed that ultrasound-guided injections were superior to blind injections for saliva reduction. VAS scores showed an improvement in the mean rate of saliva secretion in each group at first week (P<0.05). Two patients suffered from dry mouth in mild severity lasting 1 month. CONCLUSION Intraparotid BTX-A injections using ultrasound guidance may be an effective, easy, and safe treatment for parkinsonian sialorrhoea.


Neurological Sciences | 2004

Long-term effectiveness of steroid injections and splinting in mild and moderate carpal tunnel syndrome

Serhan Sevim; Okan Dogu; H. Çamdeviren; Hakan Kaleagasi; Mihriban Aral; Emrah Arslan; A. Milcan

Abstract.To evaluate the long-term efficacy of non-surgical treatment methods for mild and moderate carpal tunnel syndrome, 120 patients with clinical symptoms and electrophysiologic evidence were included in a prospective, randomized and blinded trial: 60 patients were instructed to wear splints every night, 30 received injections of betamethasone 4 cm proximal to the carpal tunnel, and 30 received injections distal to the carpal tunnel. After approximately 1 year (mean, 11 months; range, 9–14), 108 patients were available for final evaluation. We assessed clinical symptom severity and performed detailed electrophysiologic examinations before and after treatment. Splinting provided symptomatic relief and improved sensory and motor nerve conduction velocities at the long-term follow-up when the splints were worn almost every night. Proximal and distal injections of steroids were ineffective on the basis of both clinical symptoms and electrophysiologic findings.


Acta Oto-laryngologica | 2003

Effect of botulinum toxin type A on nasal symptoms in patients with allergic rhinitis: a double-blind, placebo-controlled clinical trial.

Murat Ünal; Serhan Sevim; Okan Dogu; Yusuf Vayisoglu; Arzu Kanik

Objective—To investigate the possible beneficial effects of botulinum toxin type A (BTX-A) on nasal symptoms in patients with allergic rhinitis (AR). Material and Methods—Thirty-four patients (21 females, 13 males; mean age 28 years) were included in the study. AR was diagnosed by means of history, clinical examination and skin prick test. Patients were randomly divided into 3 subgroups a follows: in Group A, 20 units of BTX-A was injected into each nasal cavity (total 40 units); in Group B, 30 units of BTX-A was injected into each nasal cavity (total 60 units); and in Group C, 2 ml of isotonic saline was injected as placebo. The symptoms of AR (rhinorrhea, nasal obstruction, sneezing, itching) were scored by the patient on a six-point scale (from 0 to 5). All of the patients were followed up at Weeks 1, 2, 4, 6 and 8; at each visit an anterior rhinoscopic examination was done and symptom scores were recorded. Results—There was no statistically significant difference between Groups A and B in terms of average symptom scores. Rhinorrhea, nasal obstruction and sneezing scores in Groups A and B were significantly better than those in Group C at all time points. Although itching scores were significantly lower at Weeks 1 and 2, there was no difference in the Week 4,6 and 8 scores in Groups A and B. When total symptom scores were evaluated, the results for Groups A and B were similar but significantly better than those for Group C. Conclusion—In selected cases, injection of 40 units of BTX-A into the turbinates, as a single agent, may help the symptomatic control of AR for up to 8 weeks.


Journal of Neurology | 2005

Clinical characteristics of essential tremorin Mersin, Turkey

Okan Dogu; Elan D. Louis; Serhan Sevim; Hakan Kaleagasi; Mihriban Aral

AbstractObjectiveTo describe the clinical features of essential tremor (ET) in a population.BackgroundWith few exceptions, clinical data on ET are derived from patients who attend specialty clinics. Most (> 90%) population–dwelling ET cases do not seek neurological attention.Methods89 ET cases living in the Mersin province, Turkey were matched to 89 controls from the same population. All were examined by neurologists. Standardized scales included the Hamilton Depression Scale (HDS) and Hamilton Anxiety Scale (HAS).ResultsEight–one (91%) of 89 cases previously had not been diagnosed as ET and 96.6% were untreated. Despite this,more than half (51.7%) of the cases answered ”yes” to the question “are you disabled in some way by your tremor”. Cases had more psychiatric symptomatology than controls (mean HDS scores = 11.4 ± 8.2 vs. 7.9 ± 6.1, p = 0.003 and mean HAS scores = 12.0 ± 8.8 vs. 6.9 ± 7.1, p < 0.001). Among ET cases, HDS scores (r = 0.24, p = 0.03) and HAS scores (r = 0.27, p = 0.01) were correlated with tremor severity.ConclusionsWe present the clinical findings of a group of largely undiagnosed and untreated populationdwelling ET cases that would not otherwise have come to neurological attention. Approximately onehalf reported functional difficulty and psychiatric symptoms were over–represented in these ET cases compared with matched controls. These findings suggest that ET, as it exists in the population, is not a completely benign entity.


Neurology | 2008

SPG11 mutations are common in familial cases of complicated hereditary spastic paraplegia

Coro Paisán-Ruiz; Okan Dogu; Arda Yilmaz; Henry Houlden; Andrew Singleton

Background: Autosomal recessive hereditary spastic paraplegia (ARHSP) with thin corpus callosum (TCC) is a common form of complex hereditary spastic paraplegia. The genetic lesion underlying ARHSP-TCC was localized to chromosome 15q13-q15 and given the designation SPG11. Recently, the gene encoding spatacsin (KIAA1840) has been shown to contain mutations that underlie the majority of ARHSP-TCC cases. Methods: We present a complete analysis of the 40 coding exons of this gene in patients with sporadic (n = 25) or familial (20 probands) complex hereditary spastic paraplegia with and without thinning of the corpus callosum. Results: We identified seven mutations, including deletions, insertions, and nonsense mutations, which were all predicted to lead to premature truncation of the protein. Conclusion: We conclude that mutations on KIAA1840 are frequent in complex autosomal recessive hereditary spastic paraplegia but an infrequent cause of sporadic complex hereditary spastic paraplegia. GLOSSARY: ARHSP = autosomal recessive hereditary spastic paraplegia; HSP = hereditary spastic paraplegia; TCC = thin corpus callosum.


Proceedings of the National Academy of Sciences of the United States of America | 2014

Mitochondrial serine protease HTRA2 p.G399S in a kindred with essential tremor and Parkinson disease

Hilal Unal Gulsuner; Suleyman Gulsuner; Fatma Nazlı Mercan; Onur Emre Onat; Tom Walsh; Hashem Shahin; Ming K. Lee; Okan Dogu; Tulay Kansu; Haluk Topaloglu; Bulent Elibol; Cenk Akbostanci; Mary Claire King; Tayfun Ozcelik; Ayse B. Tekinay

Significance Essential tremor is one of the most frequent movement disorders of humans, but its causes remain largely unknown. In a six-generation family with both essential tremor and Parkinson disease, we identified a rare missense mutation of HTRA2 as the causative allele. Family members homozygous for this allele were more severely affected than those heterozygous for this allele. The same mutation had been associated with Parkinson characteristics in mouse mutants and with Parkinson disease in some, but not all, epidemiologic studies. Our results suggest that HTRA2 may be responsible for essential tremor in some families and that homozygosity for damaging alleles of HTRA2 may be responsible for Parkinson disease. Essential tremor is one of the most frequent movement disorders of humans and can be associated with substantial disability. Some but not all persons with essential tremor develop signs of Parkinson disease, and the relationship between the conditions has not been clear. In a six-generation consanguineous Turkish kindred with both essential tremor and Parkinson disease, we carried out whole exome sequencing and pedigree analysis, identifying HTRA2 p.G399S as the allele likely responsible for both conditions. Essential tremor was present in persons either heterozygous or homozygous for this allele. Homozygosity was associated with earlier age at onset of tremor (P < 0.0001), more severe postural tremor (P < 0.0001), and more severe kinetic tremor (P = 0.0019). Homozygotes, but not heterozygotes, developed Parkinson signs in the middle age. Among population controls from the same Anatolian region as the family, frequency of HTRA2 p.G399S was 0.0027, slightly lower than other populations. HTRA2 encodes a mitochondrial serine protease. Loss of function of HtrA2 was previously shown to lead to parkinsonian features in motor neuron degeneration (mnd2) mice. HTRA2 p.G399S was previously shown to lead to mitochondrial dysfunction, altered mitochondrial morphology, and decreased protease activity, but epidemiologic studies of an association between HTRA2 and Parkinson disease yielded conflicting results. Our results suggest that in some families, HTRA2 p.G399S is responsible for hereditary essential tremor and that homozygotes for this allele develop Parkinson disease. This hypothesis has implications for understanding the pathogenesis of essential tremor and its relationship to Parkinson disease.


Neuroepidemiology | 2007

Does age of onset in essential tremor have a bimodal distribution? data from a tertiary referral setting and a population-based study

Elan D. Louis; Okan Dogu

Background/Aims: The distribution of age of onset of essential tremor (ET) is unclear, with discrepancies in the literature. Some data suggest a bimodal distribution and other data 1 late-life peak. We studied age of ET onset in 2 distinct settings: a population-based study and a tertiary referral center. Methods: Age of onset data were collected. Results: In the population, there was only a small peak at the age of ≤30 years (14.1% of cases) but a clear peak in later life (85.9% of cases). In the tertiary referral center, a bimodal distribution was apparent with 1 large peak (42.2% of cases) at the age of ≤40 years and the second large peak (57.8% of cases) in later life. Familial cases accounted for only 52.6% of young-onset cases from the population, yet 82.7% from the tertiary center. Discussion: In the population-based study, a peak in later life was clearly present but a young-onset peak was barely discernable, comprising few cases. By contrast, in a tertiary referral center, age of onset was clearly bimodal. While age of ET onset is often said to be bimodal, this may be due to the preferential referral to tertiary centers of patients with young-onset, familial ET.

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