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Papers by hakan akgun

Research paper thumbnail of Evaluation of cerebral hemodynamics of patients with chronic migraine

F1000Research, 2012

Migraine is a neurovascular disorder characterized by autonomic nervous system dysfunction and se... more Migraine is a neurovascular disorder characterized by autonomic nervous system dysfunction and severe headache attacks.

Research paper thumbnail of The effect of in vivo created vascularized neurotube on peripheric nerve regeneration

Injury, 2017

Introduction: Creating vascularized nerve conduits for treatment of nerve gaps have been research... more Introduction: Creating vascularized nerve conduits for treatment of nerve gaps have been researched, however, these methods need microsurgical anastomosis thereby complicating the nerve repair process. Thus, the concept of vascularized nerve conduits has not popularized up till now. The aim of this study is to evaluate the effects of vascularized and non-vascularized biological conduits on peripheral nerve regeneration. Material and methods: Following ethical board approval, 15 Sprague-Dawley rats were used in the study. The rats were equally divided into three groups. In group I, a silicon rod was inserted next to the sciatic nerve of the rat and connective tissue generated around this rod was used as a vascularized biological conduit. In group II, a silicon rod was inserted into the dorsum of the rat and connective tissue generated around this rod was used as a non-vascularized biological conduit. In group III, autogenic nerve graft was used to repair the nerve gap. The contralateral sciatic nerve is used as a control in all rats. Macroscopic, electrophysiological and histomorphometric evaluations were performed to determine the nerve regeneration. Results: There was no statistically significant difference between groups, in terms of latency. However, the mean amplitude of group I was found to be higher than other groups. The difference between group I and II was statistically significant. Myelinated axonal counts in group I was significantly higher than groups II and III. Conclusion: Our results showed that vascularized biological conduits provided better nerve regeneration when compared to autografts and non-vascularized biological conduits. Creation and application of vascularized conduits by using the technique described here is easy. Although this method is not an alternative to autogenic nerve grafts, our results are promising and encouraging for further studies.

Research paper thumbnail of Sciatic nerve regeneration induced by glycosaminoglycan and laminin mimetic peptide nanofiber gels

RSC Adv., 2016

Bioactive peptide gels enhance the regeneration of peripheral nerve injuries, which affect 20 mil... more Bioactive peptide gels enhance the regeneration of peripheral nerve injuries, which affect 20 million patients in the USA.

Research paper thumbnail of Decreased cerebral vasomotor reactivity in patients with obstructive sleep apnea syndrome

Sleep Medicine, 2017

Objective: In obstructive sleep apnea syndrome (OSAS), any of the activated neural, vascular, hem... more Objective: In obstructive sleep apnea syndrome (OSAS), any of the activated neural, vascular, hemodynamic, metabolic, inflammatory, and thrombotic mechanisms may be related to increased cerebrovascular disease and risk of death; however, the possible pathophysiological process between obstructive sleep apnea syndrome and stroke has not been clearly explained. We hypothesize that alterations in vasomotor reactivity in patients may be responsible for their altered cerebral blood flow, and may contribute to the increased risk of ischemic stroke. Methods: A total of 30 untreated patients with severe obstructive sleep apnea and 26 control subjects were included in the study. The mean blood flow velocity and breath holding index were measured in middle cerebral artery bilaterally in both patient and control groups by using transcranial Doppler ultrasound. We compared the values between two groups. Results: The mean blood flow velocity and breath holding indexes were significantly decreased in the patient group when compared with the control group. There were no correlations between cerebral hemodynamic parameters and polysomnographic findings in patients. Conclusion: Our findings suggest that there was a deteriorated vasodilator response to hypercapnia in patients with OSAS. This deterioration may stem from chemoreceptors or endothelial damages that lead to vascular relaxation and vasodilatation in cerebrovascular circulation. This impaired cerebral vascular regulation may contribute to the increased risk of stroke in patients with OSAS.

Research paper thumbnail of Assessment of P300 Auditory Event-Related Potentials in Acromegaly

The Endocrine Society's 93rd Annual Meeting & Expo, June 4–7, 2011 - Boston, 2011

Research paper thumbnail of Atypical Ulnar Entrapment Neuropathy, Arcade of Struthers: A Case Report

Gulhane Medical Journal, 2015

ÖZET Atipik ulnar tuzak nöropatisi, Struthers arkı: Olgu sunumu Ulnar sinir sıklıkla kübital oluk... more ÖZET Atipik ulnar tuzak nöropatisi, Struthers arkı: Olgu sunumu Ulnar sinir sıklıkla kübital olukta tuzaklanmasına karşın seyrek olarak bilek düzeyinde tuzaklanabilir ve en sık neden kronik basıdır. Kol düzeyinde ulnar sinir tuzaklanması çok nadirdir ve sadece birkaç olgu sunumu bildirilmiştir. Kol orta kısmında bulunan Struthers arkusu ulnar sinir için bir tuzak nöropati yeri olabilir ancak halen varlığı tartışmalıdır. 20 yaşında klinik olarak ulnar tuzak nöropati bulguları olan ve elektrofizyolojik olarak kolun orta kısmında tuzaklanma saptanan olgumuzda Struthers arkusunun varlığına ve önemine dikkat çekmek istedik.

Research paper thumbnail of MRI diagnosis of dural sinus—Cortical venous thrombosis: Immediate post-contrast 3D GRE T1-weighted imaging versus unenhanced MR venography and conventional MR sequences

Clinical Neurology and Neurosurgery, 2015

Primary aim is to compare the diagnostic value of contrast-enhanced 3D GRE T1-weighted sequences ... more Primary aim is to compare the diagnostic value of contrast-enhanced 3D GRE T1-weighted sequences with unenhanced MR venography and conventional magnetic resonance imaging (MRI), in detection of dural venous sinus (DVS) and cortical venous thrombosis; secondary aim is to determine the relationship between DVS thrombosis/site and gender, age, infarction or hemorrhage. We retrospectively reviewed conventional MR images, unenhanced MR venography and immediate post-contrast 3D GRE T1-weighted MR images in 30 patients (17 male and 13 female, 21-70 years old, mean age 40.1) with clinically suspected DVS thrombosis. MR examinations had been performed with 1.5T or 3T MR Scanners. DVSs were evaluated in 10 sub-segments, including cortical veins. Each set of MR images were examined separately, blinded to the final diagnosis. Associated findings were also noted and sensitivity, specificity and accuracy of each MRI technique were calculated. Final diagnosis of cortical venous and/or dural sinus thrombosis was established in 24 (80%) of 30 cases and 67 (22.3%) out of 300 segments. For detection of the thrombotic segment, sensitivity, specificity, and accuracy were 83.6%, 95.3%, and 92.7% by conventional MR sequences, 89.6%, 91.8%, and 91.3% by unenhanced MR venography, and 92.5%, 100%, and 98.3% by contrast-enhanced 3D GRE T1-weighted sequence, respectively. Infarction and hemorrhage were more frequent in cases with cortical venous thrombosis, while gender and age had no significant relation with DVS thrombosis or its site. Conventional MR sequences and unenhanced MR venography were helpful due to additional information they provided in some cases with isolated cortical venous thrombosis, with hyperintense thrombus material and with associated hemorrhage or infarction. Contrast-enhanced 3D GRE T1-weighted MRI is the most accurate imaging method for the detection of DVS and/or cortical venous thrombosis. Infarction and hemorrhage were more frequent in cases with cortical venous thrombosis.

Research paper thumbnail of Spatial tuning function of pattern visual evoked potentials in multiple sclerosis patients without optic neuritis history

Medicinski glasnik : official publication of the Medical Association of Zenica-Doboj Canton, Bosnia and Herzegovina, 2013

To explore amplitude and latency-check size function in multiple sclerosis (MS) patients without ... more To explore amplitude and latency-check size function in multiple sclerosis (MS) patients without optic neuritis history. Thirty-six MS patients and 21 control subjects were included. Pattern visual evoked responses to ive check sizes (2°, 1°, 30', 15', and 7') were recorded. P100 amplitudes were significantly reduced in 2°, 1° and 7' checks and, P100 latencies were significantly delayed in all checks in MS patients (p < 0.05). Inter-ocular amplitude/ latency differences were significantly higher in MS patients than control group (p < 0.05). The P100 amplitudes for 2° check was somewhat higher than amplitudes for 1° check in MS and control groups. However, MS patients had latter amplitude-check size function curve in large checks. In small checks, the slope of the amplitude-check size curves were similar for MS and control groups. The flattening of amplitude-check size function curve in large checks increased in MS patients with reduced P100 amplitudes. The P100...

Research paper thumbnail of Clinical and laboratory features of progressive supranuclear palsy: five cases retrospective analysis

Gulhane Medical Journal, 2012

Progresif supranükleer palsi (PSP) beyinsapı ve bazal ganglionları etkileyen nörodejeneratif hast... more Progresif supranükleer palsi (PSP) beyinsapı ve bazal ganglionları etkileyen nörodejeneratif hastalıkların bir formudur. Hastalar supranükleer oftalmopleji, postural instabilite ve hafif demansla kendini gösterirler. 1 Ocak 2005 ile 31 Aralık 2009 tarihleri arasında PSP'li 5 olguyu inceledik. Hastaların klinik bulguları, demografik bulguları, beyin manyetik rezonans görüntüleme (MRG), bellek testi ve otonomik inceleme sonuçları incelendi. Hastaların tümü L-dopa ya da dopamin agonisti alıyordu. PSP başlangıcındaki ilk tanı tüm hastalarda Parkinson hastalığıydı. Beyin MRG' de ciddi mezensefalon atrofisi vardı, mini-mental durum muayenesi predominant subkortikal frontal atrofi ile ilişkili kognitif bozulma olduğunu göstermekteydi. Hastaların üçünde otonomik testler bozuktu. Biz klinik pratikte PSP tanısının erken dönemde konulmasının halen zor olduğunu vurgulamak istedik. Buna rağmen daha iyi klinik tanı kriterlerinin ortaya konmasının hastalığın doğru yönetilmesine izin vereceğini düşünmekteyiz.

Research paper thumbnail of Normal Anatomical Features and Variations of the Vertebrobasilar Circulation and Its Branches: An Analysis with 64-Detector Row CT and 3T MR Angiographies

The Scientific World Journal, 2013

Purpose. To determine the normal anatomical features and variations of the vertebrobasilar circul... more Purpose. To determine the normal anatomical features and variations of the vertebrobasilar circulation and its branches in patients who underwent multidetector computed tomography (CT) or magnetic resonance (MR) angiographies of the brain. Methods. 135 patients (male, 83 and female, 52; mean age, 50.1 years) who underwent CT (= 71) or MR (= 64) angiographies of the vertebrobasilar vasculature for various reasons were analyzed retrospectively. The right and left distal vertebral arteries (VAs), posterior inferior cerebellar arteries (PICAs), anterior inferior cerebellar arteries (AICAs), superior cerebellar arteries (SCAs), posterior cerebral arteries (PCAs), and posterior communicating arteries (PCoAs) were analyzed individually. Results. In 24.4% of the cases (33/135) right PICA, in 19.3% of the cases (26/135) left PICA, in 17.8% of the cases (24/135) right AICA, and in 18.5% of the cases (25/135) left AICA were absent. In cases without PICA or AICA, there was a statistically significant, moderately or welldeveloped AICA or PICA on the same side, respectively (< 0.001). The most common variation was isolated absence of right PICA and was seen in 17.8% of the cases. Conclusions. The anatomic features of the branches of the vertebrobasilar circulation may be different from well-known normal anatomy. CT and MR angiographies allow a precise and detailed evaluation of vertebrobasilar circulation.

Research paper thumbnail of Differential diagnosis of the complex regional pain syndrome

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 2013

4. Terao T, Ishii T, Kawamura D, et al. Diagnosis of patients with thoracic outlet syndrome (TOS)... more 4. Terao T, Ishii T, Kawamura D, et al. Diagnosis of patients with thoracic outlet syndrome (TOS) using physiological measures of the medial antebrachial cutaneous nerve. No Shinkei Geka. 2012;40:685-694. 5. Caputo FJ, Wittenberg AM, Vemuri C, et al. Supraclavicular decompression for neurogenic thoracic outlet syndrome in adolescent and adult populations. J Vasc Surg. 2013;57:149-157. 6. Ward AS, Chand M. Venous complications of thoracic outlet syndrome. Br J Hosp Med (Lond). 2011;72:511-514. 7. Kuroki T, Kumano K, Hirabayashi S. Usefulness of MRI in the preoperative diagnosis of cervical disk herniation. Arch Orthop Trauma Surg. 1993;112:180-184. 8. Bennett AJ, Wastell DG, Barker GR, Blackburn CW, Rood JP. Trigeminal somatosensory evoked potentials. A review of the literature as applicable to oral dysaesthesias. Int J Oral Maxillofac Surg. 1987;16:408-415. 9. Barker GR, Bennett AJ, Wastell DG. Applications of trigeminal somatosensory evoked potentials (TSEPs) in oral and maxillofacial surgery. Br J Oral Maxillofac Surg. 1987;25:308-313.

Research paper thumbnail of Cerebral Venous Sinus Thrombosis; Analysis of 17 Cases

Gulhane Medical Journal, 2014

Research paper thumbnail of Importance of cutaneous silent period in fibromyalgia and its relationship with disease characteristics, psychological disorders and quality of life of patients

Revista Brasileira de Reumatologia (English Edition), 2013

Introduction: Cutaneous silent period (CSP) is an inhibitory spinal protective refl ex and its af... more Introduction: Cutaneous silent period (CSP) is an inhibitory spinal protective refl ex and its afferents consist of A-delta nerve fi bers. We aimed to evaluate patients with fi bromyalgia (FM) and healthy controls to determine any differences between the groups in terms of CSP duration and latency, and if present, to determine whether there is any relationship with disease characteristics, psychological disorders and quality of life. Materials and methods: Thirty-two patients with FM and 32 healthy volunteers were included in the study. The patient and control groups were compared in terms of CSP latency and duration in both upper and lower extremities. Disease characteristics, psychological disorders and quality of life of patients were assessed using the Fibromyalgia Impact Questionnaire (FIQ) and Short Form-36 (SF-36). Patients with CSP measurements equal to or lower than those of the control group were compared with those with higher values than controls in terms of disease characteristics, psychological status and quality of life. Results: Signifi cantly prolonged CSP latencies in both upper and lower extremities were determined in patients compared to controls. We found that prolongation of CSP latency in the lower extremity is associated with disease severity and functional disability. Conclusions: CSP latencies in both upper and lower extremities in patients with FM are longer than in healthy volunteers. Moreover, prolongation of CSP latency in the lower extremity is associated with disease severity and physical functional disability.

Research paper thumbnail of Validity of Late-Term Electroneurography in Bell’s Palsy

Otology & Neurotology, 2014

Objective: To evaluate the validity of early (within 3 wk) and late-term (after 3 wk) electroneur... more Objective: To evaluate the validity of early (within 3 wk) and late-term (after 3 wk) electroneurography (ENoG) findings in Bell's palsy (BP) to predict the prognosis. Study Design: Retrospective case review. Setting: Tertiary referral center. Patients: Patients with peripheral facial paralysis with no identified cause. All patients were given the same treatment. Intervention(s): House Brackmann (HB) grading and ENoG. Main Outcome Measures: The records of 38 patients with BP were retrospectively analyzed. This study included only those patients who had been followed up for at least 4 months on a regular basis or until complete recovery. ENoG was performed for orbicularis oculi and orbicularis oris muscles and degeneration ratio was calculated separately. Correlation between HB grading and ENoG findings, relationship between duration for maximum recovery and ENoG findings, and also initial HB grading and recovery rate were investigated. Results: Complete recovery rate was significantly higher in patients with HB grades I to III at initial examination. A significant correlation was found between HB grading and degree of ENoG degeneration at the 7th and 14th days of FP. Patients with degeneration less than 80% for orbicularis oculi and less than 65% for orbicularis oris had significantly better and faster recovery than those with higher level of degeneration (p G 0.05). Conclusion: ENoG and HB grading during first to fourth weeks of BP are useful prognostic indicators. Serial ENoG examinations are recommended to predict the status of neural degeneration and the prognosis of the palsy. However, ENoG in late term may not be compatible with clinical facial function.

Research paper thumbnail of Effect of pramipexole on cutaneous-silent-period parameters in patients with restless legs syndrome

Clinical Neurophysiology, 2012

The aim of this study was to investigate cutaneous-silent-period (CSP) parameters in patients wit... more The aim of this study was to investigate cutaneous-silent-period (CSP) parameters in patients with restless legs syndrome (RLS) and examine the effects of treatment on CSP which, to our knowledge, have not been investigated till date. A total of 25 patients with RLS and 25 healthy volunteers were studied. CSP latency and duration in the upper and lower extremities were examined in the two groups. In RLS patients, the variables were examined before and after pramipexole treatment. Lower-extremity CSP latency was longer (106.22±11.69 ms vs. 91.67±8.53 ms; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001) and CSP duration was shorter (35.50±10.91 ms vs. 49.47±6.43 ms; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001) in patients, compared with controls. In the patient group, CSP durations in the upper (40.88±7.95 ms vs. 46.84±10.22 ms; p=0.006) and lower extremities (35.50±10.91 ms vs. 44.91±6.43 ms; p=0.005) were prolonged after treatment, compared with pre-treatment values. Small-fibre neuropathy may exist in RLS. In addition, we suggest that pramipexole may regulate cortical and spinal inhibitory mechanisms. The use of CSP may aid in the diagnosis of RLS and may be used as a measure of treatment effectiveness.

Research paper thumbnail of Usefulness of somatosensory and motor evoked potentials for lesion localization

Clinical Neurology and Neurosurgery, 2013

Isolated brainstem cysticercosis Sir, The recent article on isolated brainstem cysticercosis is v... more Isolated brainstem cysticercosis Sir, The recent article on isolated brainstem cysticercosis is very interesting [1]. Del Brutto et al. concluded that this condition can present as "space-occupying lesion" and also mentioned that "The prognosis is benign provided the patients receive prompt therapy [1]." Some additional concerns should be mentioned. First, the differential diagnosis from other space occupying lesions is needed. However, the diagnosis by neuroimaging might be very difficult. Chang et al. concluded that "The clinical and radiographic features of neurocysticercosis are highly variable [2]." The final diagnosis has to be based on "surgical and histopathological findings [2]." Furthermore, the concurrent neurocysticercosis and tumor can be seen and this should not be missed [3]. Focusing on the course of disease, it sometimes can be fatal. Basilar infestation can induce brain herniation and can result in death [4].

Research paper thumbnail of Two conjoined plaques or a flap?

Annals of Indian Academy of Neurology, 2013

Research paper thumbnail of Migraine and restless leg syndrome co-morbidity may be due to iron deficiency

Annals of Indian Academy of Neurology, 2013

Letters to the Editor 461 Migraine and restless leg syndrome co-morbidity may be due to iron defi... more Letters to the Editor 461 Migraine and restless leg syndrome co-morbidity may be due to iron deficiency Sir, We inspected Gupta et al.'s [1] study carefully. The authors investigated the effect of restless leg syndrome (RLS) on the formation of migraine-type headache. Our opinion is that iron deficiency may have an effect on the pathophysiology of migraine seen in RLS patients. So we recommend the readers to keep in mind that iron deficiency might have an effect on migraine formation in RLS patients. Furthermore, when we inspected Gupta et al.'s [1] study carefully, the authors investigated the effect of RLS on the formation of migraine-type headache. They focused on the hypothesis that the frequency and duration of RLS symptoms, sleep disturbance, and increased prevalence of depression, and positive family history, all caused by RLS, contribute in the formation of migrain-type headache. These factors are likely to contribute to the formation of migraine, as mentioned in the study. However, it is a recognized fact that iron deficiency is seen in RLS patients.

Research paper thumbnail of Plexitis or radiculitis secondary to bee sting

Annals of Indian Academy of Neurology, 2013

We have read Jithendranath et al.'s case report with interest. [1] They have presented a patient ... more We have read Jithendranath et al.'s case report with interest. [1] They have presented a patient with brachial plexitis after multiple bee stings. On the electromyography (EMG) report, nerve conduction studies were consistent with brachial plexus lesion located at the root level of C6, C7, C8, and T1 on the right. They have stated that brachial plexitis is possibly secondary to peripheral action on the nerve roots resulting from allergic reaction to the bee venom. However, some questions left in the minds of us, the readers. It was stated that nerve conduction studies were performed; however, what was not clarified was the day the studies were performed and whether needle EMG studies were performed. If needle EMG studies were performed were there any denervation potentials observed? There is no clear information concerning this issue. An edema on the patient's hand was mentioned. If only nerve conduction tests were performed a decrease of the conjoined muscle amplitudes can be observed secondary to the edema. This is worth keeping in mind. The brachial plexus and the roots are described separately. Brachial plexus consists of upper, middle, and lower roots. In this patient, the roots are described to be affected. It is not clear whether the roots or brachial plexus is involved. Brachial plexus magnetic resonance imaging (MRI) was normal. In cases with brachial plexitis, contrast enhancement of the brachial plexus is detected. The brachial plexus MRI can be normal if contrast is not used. For the reasons stated, some unanswered questions left in our minds. We advise the authors to bring light on this issue.

Research paper thumbnail of Demographic, clinical, and polysomnographic features in patients with narcolepsy: an experience of 181 patients with narcolepsy from a Turkish sleep center

Acta Neurologica Belgica, 2012

The present study was designed to describe the socio-demographic, clinical, and polysomnographic ... more The present study was designed to describe the socio-demographic, clinical, and polysomnographic features of patients diagnosed with narcolepsy in our sleep center. This retrospective cross-sectional study was conducted on 181 patients diagnosed with narcolepsy based on the results of clinical evaluation, polysomnography (PSG), and multiple sleep latency test (MSLT) between 1993 and 2009. Approximately 70% of the patients had cataplexy, whereas 42% had hallucinations and 55.8% had sleep paralysis. Although sleep efficiency was higher (91.28 ± 5.89%) in patients with narcolepsy, they woke frequently during the night, and their percentages of deep sleep were low (stage 3, 5.12 ± 3.08%, stage 4, 9.60 ± 7.10%). Our study group was divided into two based on age: individuals aged\30 years (n = 152) and [30 years (n = 29). REM latency on PSG was shorter (t = 2.96, p = 0.004) and sleep onset REM (SOREM) on MSLT was higher (t = 2.56, p = 0.011) in the older group than in the younger group. Cataplexy is seen in most patients with narcolepsy. In older patients, REM latency on PSG is shorter and the number of SOREM on MSLT is higher.

Research paper thumbnail of Evaluation of cerebral hemodynamics of patients with chronic migraine

F1000Research, 2012

Migraine is a neurovascular disorder characterized by autonomic nervous system dysfunction and se... more Migraine is a neurovascular disorder characterized by autonomic nervous system dysfunction and severe headache attacks.

Research paper thumbnail of The effect of in vivo created vascularized neurotube on peripheric nerve regeneration

Injury, 2017

Introduction: Creating vascularized nerve conduits for treatment of nerve gaps have been research... more Introduction: Creating vascularized nerve conduits for treatment of nerve gaps have been researched, however, these methods need microsurgical anastomosis thereby complicating the nerve repair process. Thus, the concept of vascularized nerve conduits has not popularized up till now. The aim of this study is to evaluate the effects of vascularized and non-vascularized biological conduits on peripheral nerve regeneration. Material and methods: Following ethical board approval, 15 Sprague-Dawley rats were used in the study. The rats were equally divided into three groups. In group I, a silicon rod was inserted next to the sciatic nerve of the rat and connective tissue generated around this rod was used as a vascularized biological conduit. In group II, a silicon rod was inserted into the dorsum of the rat and connective tissue generated around this rod was used as a non-vascularized biological conduit. In group III, autogenic nerve graft was used to repair the nerve gap. The contralateral sciatic nerve is used as a control in all rats. Macroscopic, electrophysiological and histomorphometric evaluations were performed to determine the nerve regeneration. Results: There was no statistically significant difference between groups, in terms of latency. However, the mean amplitude of group I was found to be higher than other groups. The difference between group I and II was statistically significant. Myelinated axonal counts in group I was significantly higher than groups II and III. Conclusion: Our results showed that vascularized biological conduits provided better nerve regeneration when compared to autografts and non-vascularized biological conduits. Creation and application of vascularized conduits by using the technique described here is easy. Although this method is not an alternative to autogenic nerve grafts, our results are promising and encouraging for further studies.

Research paper thumbnail of Sciatic nerve regeneration induced by glycosaminoglycan and laminin mimetic peptide nanofiber gels

RSC Adv., 2016

Bioactive peptide gels enhance the regeneration of peripheral nerve injuries, which affect 20 mil... more Bioactive peptide gels enhance the regeneration of peripheral nerve injuries, which affect 20 million patients in the USA.

Research paper thumbnail of Decreased cerebral vasomotor reactivity in patients with obstructive sleep apnea syndrome

Sleep Medicine, 2017

Objective: In obstructive sleep apnea syndrome (OSAS), any of the activated neural, vascular, hem... more Objective: In obstructive sleep apnea syndrome (OSAS), any of the activated neural, vascular, hemodynamic, metabolic, inflammatory, and thrombotic mechanisms may be related to increased cerebrovascular disease and risk of death; however, the possible pathophysiological process between obstructive sleep apnea syndrome and stroke has not been clearly explained. We hypothesize that alterations in vasomotor reactivity in patients may be responsible for their altered cerebral blood flow, and may contribute to the increased risk of ischemic stroke. Methods: A total of 30 untreated patients with severe obstructive sleep apnea and 26 control subjects were included in the study. The mean blood flow velocity and breath holding index were measured in middle cerebral artery bilaterally in both patient and control groups by using transcranial Doppler ultrasound. We compared the values between two groups. Results: The mean blood flow velocity and breath holding indexes were significantly decreased in the patient group when compared with the control group. There were no correlations between cerebral hemodynamic parameters and polysomnographic findings in patients. Conclusion: Our findings suggest that there was a deteriorated vasodilator response to hypercapnia in patients with OSAS. This deterioration may stem from chemoreceptors or endothelial damages that lead to vascular relaxation and vasodilatation in cerebrovascular circulation. This impaired cerebral vascular regulation may contribute to the increased risk of stroke in patients with OSAS.

Research paper thumbnail of Assessment of P300 Auditory Event-Related Potentials in Acromegaly

The Endocrine Society's 93rd Annual Meeting & Expo, June 4–7, 2011 - Boston, 2011

Research paper thumbnail of Atypical Ulnar Entrapment Neuropathy, Arcade of Struthers: A Case Report

Gulhane Medical Journal, 2015

ÖZET Atipik ulnar tuzak nöropatisi, Struthers arkı: Olgu sunumu Ulnar sinir sıklıkla kübital oluk... more ÖZET Atipik ulnar tuzak nöropatisi, Struthers arkı: Olgu sunumu Ulnar sinir sıklıkla kübital olukta tuzaklanmasına karşın seyrek olarak bilek düzeyinde tuzaklanabilir ve en sık neden kronik basıdır. Kol düzeyinde ulnar sinir tuzaklanması çok nadirdir ve sadece birkaç olgu sunumu bildirilmiştir. Kol orta kısmında bulunan Struthers arkusu ulnar sinir için bir tuzak nöropati yeri olabilir ancak halen varlığı tartışmalıdır. 20 yaşında klinik olarak ulnar tuzak nöropati bulguları olan ve elektrofizyolojik olarak kolun orta kısmında tuzaklanma saptanan olgumuzda Struthers arkusunun varlığına ve önemine dikkat çekmek istedik.

Research paper thumbnail of MRI diagnosis of dural sinus—Cortical venous thrombosis: Immediate post-contrast 3D GRE T1-weighted imaging versus unenhanced MR venography and conventional MR sequences

Clinical Neurology and Neurosurgery, 2015

Primary aim is to compare the diagnostic value of contrast-enhanced 3D GRE T1-weighted sequences ... more Primary aim is to compare the diagnostic value of contrast-enhanced 3D GRE T1-weighted sequences with unenhanced MR venography and conventional magnetic resonance imaging (MRI), in detection of dural venous sinus (DVS) and cortical venous thrombosis; secondary aim is to determine the relationship between DVS thrombosis/site and gender, age, infarction or hemorrhage. We retrospectively reviewed conventional MR images, unenhanced MR venography and immediate post-contrast 3D GRE T1-weighted MR images in 30 patients (17 male and 13 female, 21-70 years old, mean age 40.1) with clinically suspected DVS thrombosis. MR examinations had been performed with 1.5T or 3T MR Scanners. DVSs were evaluated in 10 sub-segments, including cortical veins. Each set of MR images were examined separately, blinded to the final diagnosis. Associated findings were also noted and sensitivity, specificity and accuracy of each MRI technique were calculated. Final diagnosis of cortical venous and/or dural sinus thrombosis was established in 24 (80%) of 30 cases and 67 (22.3%) out of 300 segments. For detection of the thrombotic segment, sensitivity, specificity, and accuracy were 83.6%, 95.3%, and 92.7% by conventional MR sequences, 89.6%, 91.8%, and 91.3% by unenhanced MR venography, and 92.5%, 100%, and 98.3% by contrast-enhanced 3D GRE T1-weighted sequence, respectively. Infarction and hemorrhage were more frequent in cases with cortical venous thrombosis, while gender and age had no significant relation with DVS thrombosis or its site. Conventional MR sequences and unenhanced MR venography were helpful due to additional information they provided in some cases with isolated cortical venous thrombosis, with hyperintense thrombus material and with associated hemorrhage or infarction. Contrast-enhanced 3D GRE T1-weighted MRI is the most accurate imaging method for the detection of DVS and/or cortical venous thrombosis. Infarction and hemorrhage were more frequent in cases with cortical venous thrombosis.

Research paper thumbnail of Spatial tuning function of pattern visual evoked potentials in multiple sclerosis patients without optic neuritis history

Medicinski glasnik : official publication of the Medical Association of Zenica-Doboj Canton, Bosnia and Herzegovina, 2013

To explore amplitude and latency-check size function in multiple sclerosis (MS) patients without ... more To explore amplitude and latency-check size function in multiple sclerosis (MS) patients without optic neuritis history. Thirty-six MS patients and 21 control subjects were included. Pattern visual evoked responses to ive check sizes (2°, 1°, 30', 15', and 7') were recorded. P100 amplitudes were significantly reduced in 2°, 1° and 7' checks and, P100 latencies were significantly delayed in all checks in MS patients (p < 0.05). Inter-ocular amplitude/ latency differences were significantly higher in MS patients than control group (p < 0.05). The P100 amplitudes for 2° check was somewhat higher than amplitudes for 1° check in MS and control groups. However, MS patients had latter amplitude-check size function curve in large checks. In small checks, the slope of the amplitude-check size curves were similar for MS and control groups. The flattening of amplitude-check size function curve in large checks increased in MS patients with reduced P100 amplitudes. The P100...

Research paper thumbnail of Clinical and laboratory features of progressive supranuclear palsy: five cases retrospective analysis

Gulhane Medical Journal, 2012

Progresif supranükleer palsi (PSP) beyinsapı ve bazal ganglionları etkileyen nörodejeneratif hast... more Progresif supranükleer palsi (PSP) beyinsapı ve bazal ganglionları etkileyen nörodejeneratif hastalıkların bir formudur. Hastalar supranükleer oftalmopleji, postural instabilite ve hafif demansla kendini gösterirler. 1 Ocak 2005 ile 31 Aralık 2009 tarihleri arasında PSP'li 5 olguyu inceledik. Hastaların klinik bulguları, demografik bulguları, beyin manyetik rezonans görüntüleme (MRG), bellek testi ve otonomik inceleme sonuçları incelendi. Hastaların tümü L-dopa ya da dopamin agonisti alıyordu. PSP başlangıcındaki ilk tanı tüm hastalarda Parkinson hastalığıydı. Beyin MRG' de ciddi mezensefalon atrofisi vardı, mini-mental durum muayenesi predominant subkortikal frontal atrofi ile ilişkili kognitif bozulma olduğunu göstermekteydi. Hastaların üçünde otonomik testler bozuktu. Biz klinik pratikte PSP tanısının erken dönemde konulmasının halen zor olduğunu vurgulamak istedik. Buna rağmen daha iyi klinik tanı kriterlerinin ortaya konmasının hastalığın doğru yönetilmesine izin vereceğini düşünmekteyiz.

Research paper thumbnail of Normal Anatomical Features and Variations of the Vertebrobasilar Circulation and Its Branches: An Analysis with 64-Detector Row CT and 3T MR Angiographies

The Scientific World Journal, 2013

Purpose. To determine the normal anatomical features and variations of the vertebrobasilar circul... more Purpose. To determine the normal anatomical features and variations of the vertebrobasilar circulation and its branches in patients who underwent multidetector computed tomography (CT) or magnetic resonance (MR) angiographies of the brain. Methods. 135 patients (male, 83 and female, 52; mean age, 50.1 years) who underwent CT (= 71) or MR (= 64) angiographies of the vertebrobasilar vasculature for various reasons were analyzed retrospectively. The right and left distal vertebral arteries (VAs), posterior inferior cerebellar arteries (PICAs), anterior inferior cerebellar arteries (AICAs), superior cerebellar arteries (SCAs), posterior cerebral arteries (PCAs), and posterior communicating arteries (PCoAs) were analyzed individually. Results. In 24.4% of the cases (33/135) right PICA, in 19.3% of the cases (26/135) left PICA, in 17.8% of the cases (24/135) right AICA, and in 18.5% of the cases (25/135) left AICA were absent. In cases without PICA or AICA, there was a statistically significant, moderately or welldeveloped AICA or PICA on the same side, respectively (< 0.001). The most common variation was isolated absence of right PICA and was seen in 17.8% of the cases. Conclusions. The anatomic features of the branches of the vertebrobasilar circulation may be different from well-known normal anatomy. CT and MR angiographies allow a precise and detailed evaluation of vertebrobasilar circulation.

Research paper thumbnail of Differential diagnosis of the complex regional pain syndrome

Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 2013

4. Terao T, Ishii T, Kawamura D, et al. Diagnosis of patients with thoracic outlet syndrome (TOS)... more 4. Terao T, Ishii T, Kawamura D, et al. Diagnosis of patients with thoracic outlet syndrome (TOS) using physiological measures of the medial antebrachial cutaneous nerve. No Shinkei Geka. 2012;40:685-694. 5. Caputo FJ, Wittenberg AM, Vemuri C, et al. Supraclavicular decompression for neurogenic thoracic outlet syndrome in adolescent and adult populations. J Vasc Surg. 2013;57:149-157. 6. Ward AS, Chand M. Venous complications of thoracic outlet syndrome. Br J Hosp Med (Lond). 2011;72:511-514. 7. Kuroki T, Kumano K, Hirabayashi S. Usefulness of MRI in the preoperative diagnosis of cervical disk herniation. Arch Orthop Trauma Surg. 1993;112:180-184. 8. Bennett AJ, Wastell DG, Barker GR, Blackburn CW, Rood JP. Trigeminal somatosensory evoked potentials. A review of the literature as applicable to oral dysaesthesias. Int J Oral Maxillofac Surg. 1987;16:408-415. 9. Barker GR, Bennett AJ, Wastell DG. Applications of trigeminal somatosensory evoked potentials (TSEPs) in oral and maxillofacial surgery. Br J Oral Maxillofac Surg. 1987;25:308-313.

Research paper thumbnail of Cerebral Venous Sinus Thrombosis; Analysis of 17 Cases

Gulhane Medical Journal, 2014

Research paper thumbnail of Importance of cutaneous silent period in fibromyalgia and its relationship with disease characteristics, psychological disorders and quality of life of patients

Revista Brasileira de Reumatologia (English Edition), 2013

Introduction: Cutaneous silent period (CSP) is an inhibitory spinal protective refl ex and its af... more Introduction: Cutaneous silent period (CSP) is an inhibitory spinal protective refl ex and its afferents consist of A-delta nerve fi bers. We aimed to evaluate patients with fi bromyalgia (FM) and healthy controls to determine any differences between the groups in terms of CSP duration and latency, and if present, to determine whether there is any relationship with disease characteristics, psychological disorders and quality of life. Materials and methods: Thirty-two patients with FM and 32 healthy volunteers were included in the study. The patient and control groups were compared in terms of CSP latency and duration in both upper and lower extremities. Disease characteristics, psychological disorders and quality of life of patients were assessed using the Fibromyalgia Impact Questionnaire (FIQ) and Short Form-36 (SF-36). Patients with CSP measurements equal to or lower than those of the control group were compared with those with higher values than controls in terms of disease characteristics, psychological status and quality of life. Results: Signifi cantly prolonged CSP latencies in both upper and lower extremities were determined in patients compared to controls. We found that prolongation of CSP latency in the lower extremity is associated with disease severity and functional disability. Conclusions: CSP latencies in both upper and lower extremities in patients with FM are longer than in healthy volunteers. Moreover, prolongation of CSP latency in the lower extremity is associated with disease severity and physical functional disability.

Research paper thumbnail of Validity of Late-Term Electroneurography in Bell’s Palsy

Otology & Neurotology, 2014

Objective: To evaluate the validity of early (within 3 wk) and late-term (after 3 wk) electroneur... more Objective: To evaluate the validity of early (within 3 wk) and late-term (after 3 wk) electroneurography (ENoG) findings in Bell's palsy (BP) to predict the prognosis. Study Design: Retrospective case review. Setting: Tertiary referral center. Patients: Patients with peripheral facial paralysis with no identified cause. All patients were given the same treatment. Intervention(s): House Brackmann (HB) grading and ENoG. Main Outcome Measures: The records of 38 patients with BP were retrospectively analyzed. This study included only those patients who had been followed up for at least 4 months on a regular basis or until complete recovery. ENoG was performed for orbicularis oculi and orbicularis oris muscles and degeneration ratio was calculated separately. Correlation between HB grading and ENoG findings, relationship between duration for maximum recovery and ENoG findings, and also initial HB grading and recovery rate were investigated. Results: Complete recovery rate was significantly higher in patients with HB grades I to III at initial examination. A significant correlation was found between HB grading and degree of ENoG degeneration at the 7th and 14th days of FP. Patients with degeneration less than 80% for orbicularis oculi and less than 65% for orbicularis oris had significantly better and faster recovery than those with higher level of degeneration (p G 0.05). Conclusion: ENoG and HB grading during first to fourth weeks of BP are useful prognostic indicators. Serial ENoG examinations are recommended to predict the status of neural degeneration and the prognosis of the palsy. However, ENoG in late term may not be compatible with clinical facial function.

Research paper thumbnail of Effect of pramipexole on cutaneous-silent-period parameters in patients with restless legs syndrome

Clinical Neurophysiology, 2012

The aim of this study was to investigate cutaneous-silent-period (CSP) parameters in patients wit... more The aim of this study was to investigate cutaneous-silent-period (CSP) parameters in patients with restless legs syndrome (RLS) and examine the effects of treatment on CSP which, to our knowledge, have not been investigated till date. A total of 25 patients with RLS and 25 healthy volunteers were studied. CSP latency and duration in the upper and lower extremities were examined in the two groups. In RLS patients, the variables were examined before and after pramipexole treatment. Lower-extremity CSP latency was longer (106.22±11.69 ms vs. 91.67±8.53 ms; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001) and CSP duration was shorter (35.50±10.91 ms vs. 49.47±6.43 ms; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001) in patients, compared with controls. In the patient group, CSP durations in the upper (40.88±7.95 ms vs. 46.84±10.22 ms; p=0.006) and lower extremities (35.50±10.91 ms vs. 44.91±6.43 ms; p=0.005) were prolonged after treatment, compared with pre-treatment values. Small-fibre neuropathy may exist in RLS. In addition, we suggest that pramipexole may regulate cortical and spinal inhibitory mechanisms. The use of CSP may aid in the diagnosis of RLS and may be used as a measure of treatment effectiveness.

Research paper thumbnail of Usefulness of somatosensory and motor evoked potentials for lesion localization

Clinical Neurology and Neurosurgery, 2013

Isolated brainstem cysticercosis Sir, The recent article on isolated brainstem cysticercosis is v... more Isolated brainstem cysticercosis Sir, The recent article on isolated brainstem cysticercosis is very interesting [1]. Del Brutto et al. concluded that this condition can present as "space-occupying lesion" and also mentioned that "The prognosis is benign provided the patients receive prompt therapy [1]." Some additional concerns should be mentioned. First, the differential diagnosis from other space occupying lesions is needed. However, the diagnosis by neuroimaging might be very difficult. Chang et al. concluded that "The clinical and radiographic features of neurocysticercosis are highly variable [2]." The final diagnosis has to be based on "surgical and histopathological findings [2]." Furthermore, the concurrent neurocysticercosis and tumor can be seen and this should not be missed [3]. Focusing on the course of disease, it sometimes can be fatal. Basilar infestation can induce brain herniation and can result in death [4].

Research paper thumbnail of Two conjoined plaques or a flap?

Annals of Indian Academy of Neurology, 2013

Research paper thumbnail of Migraine and restless leg syndrome co-morbidity may be due to iron deficiency

Annals of Indian Academy of Neurology, 2013

Letters to the Editor 461 Migraine and restless leg syndrome co-morbidity may be due to iron defi... more Letters to the Editor 461 Migraine and restless leg syndrome co-morbidity may be due to iron deficiency Sir, We inspected Gupta et al.'s [1] study carefully. The authors investigated the effect of restless leg syndrome (RLS) on the formation of migraine-type headache. Our opinion is that iron deficiency may have an effect on the pathophysiology of migraine seen in RLS patients. So we recommend the readers to keep in mind that iron deficiency might have an effect on migraine formation in RLS patients. Furthermore, when we inspected Gupta et al.'s [1] study carefully, the authors investigated the effect of RLS on the formation of migraine-type headache. They focused on the hypothesis that the frequency and duration of RLS symptoms, sleep disturbance, and increased prevalence of depression, and positive family history, all caused by RLS, contribute in the formation of migrain-type headache. These factors are likely to contribute to the formation of migraine, as mentioned in the study. However, it is a recognized fact that iron deficiency is seen in RLS patients.

Research paper thumbnail of Plexitis or radiculitis secondary to bee sting

Annals of Indian Academy of Neurology, 2013

We have read Jithendranath et al.'s case report with interest. [1] They have presented a patient ... more We have read Jithendranath et al.'s case report with interest. [1] They have presented a patient with brachial plexitis after multiple bee stings. On the electromyography (EMG) report, nerve conduction studies were consistent with brachial plexus lesion located at the root level of C6, C7, C8, and T1 on the right. They have stated that brachial plexitis is possibly secondary to peripheral action on the nerve roots resulting from allergic reaction to the bee venom. However, some questions left in the minds of us, the readers. It was stated that nerve conduction studies were performed; however, what was not clarified was the day the studies were performed and whether needle EMG studies were performed. If needle EMG studies were performed were there any denervation potentials observed? There is no clear information concerning this issue. An edema on the patient's hand was mentioned. If only nerve conduction tests were performed a decrease of the conjoined muscle amplitudes can be observed secondary to the edema. This is worth keeping in mind. The brachial plexus and the roots are described separately. Brachial plexus consists of upper, middle, and lower roots. In this patient, the roots are described to be affected. It is not clear whether the roots or brachial plexus is involved. Brachial plexus magnetic resonance imaging (MRI) was normal. In cases with brachial plexitis, contrast enhancement of the brachial plexus is detected. The brachial plexus MRI can be normal if contrast is not used. For the reasons stated, some unanswered questions left in our minds. We advise the authors to bring light on this issue.

Research paper thumbnail of Demographic, clinical, and polysomnographic features in patients with narcolepsy: an experience of 181 patients with narcolepsy from a Turkish sleep center

Acta Neurologica Belgica, 2012

The present study was designed to describe the socio-demographic, clinical, and polysomnographic ... more The present study was designed to describe the socio-demographic, clinical, and polysomnographic features of patients diagnosed with narcolepsy in our sleep center. This retrospective cross-sectional study was conducted on 181 patients diagnosed with narcolepsy based on the results of clinical evaluation, polysomnography (PSG), and multiple sleep latency test (MSLT) between 1993 and 2009. Approximately 70% of the patients had cataplexy, whereas 42% had hallucinations and 55.8% had sleep paralysis. Although sleep efficiency was higher (91.28 ± 5.89%) in patients with narcolepsy, they woke frequently during the night, and their percentages of deep sleep were low (stage 3, 5.12 ± 3.08%, stage 4, 9.60 ± 7.10%). Our study group was divided into two based on age: individuals aged\30 years (n = 152) and [30 years (n = 29). REM latency on PSG was shorter (t = 2.96, p = 0.004) and sleep onset REM (SOREM) on MSLT was higher (t = 2.56, p = 0.011) in the older group than in the younger group. Cataplexy is seen in most patients with narcolepsy. In older patients, REM latency on PSG is shorter and the number of SOREM on MSLT is higher.