Hakan Akgün

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

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 (n = 71) or MR (n = 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 well-developed AICA or PICA on the same side, respectively (P < 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.

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

OBJECTIVE 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. METHODS 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. RESULTS 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. CONCLUSION 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.

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

OBJECTIVE 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. METHODS 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. RESULTS Lower-extremity CSP latency was longer (106.22±11.69 ms vs. 91.67±8.53 ms; p<0.001) and CSP duration was shorter (35.50±10.91 ms vs. 49.47±6.43 ms; p<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. CONCLUSIONS Small-fibre neuropathy may exist in RLS. In addition, we suggest that pramipexole may regulate cortical and spinal inhibitory mechanisms. SIGNIFICANCE The use of CSP may aid in the diagnosis of RLS and may be used as a measure of treatment effectiveness.

Effects of topiramate on peripheral nerve excitability.

Purpose: Antiepileptic drugs are generally used to control the cortical hyperexcitable states. But some of them are also effective on the peripheral nervous system, so they may be used in some states like neuropathic pain. Several recent reports suggest the possible effects of antiepileptic drugs on peripheral nerve excitability. Strength duration time properties gives an indirect idea about the persistent, paranodal sodium (Na) channels and may indirectly reflect the peripheral nerve excitability. Topiramate suppresses the cortical hyperexcitability, but previous studies could not prove a significant effect of topiramate on peripheral nerves. The aim of this study is to investigate the probable nerve excitability changes caused by topiramate. Methods: Forty migraine patients and 40 controls were included in the study. Median motor and sensory conduction parameters were recorded. Strength duration properties were also recorded from abductor pollicis longus muscle, with the stimulation of median nerve. The electrophysiological studies were repeated 4 weeks after the initiation of topiramate in the treatment group. Results: Nerve conduction parameters were not significantly affected by 4-week topiramate treatment. But the strength duration time constant decreased significantly, reflecting a reduction in the excitability. This decrement seemed to be more obvious in those in whom topiramate was also clinically useful. Conclusions: The method used demonstrated a probable effect of topiramate on the peripheral nerve excitability.

Sciatic nerve regeneration induced by glycosaminoglycan and laminin mimetic peptide nanofiber gels

In the USA, 20 million patients suffer from neuropathy caused by peripheral nerve injuries, which costs approximately

Nerve excitability properties in early preclinical diabetic neuropathy

150 billion annually. For longer nerve gaps and multiple injury sites, it is essential to use nerve guidance conduits for healthy pathfinding of regenerating axons. Here, extracellular matrix mimetic peptide nanofiber hydrogels were used for functionalizing guidance conduits to enhance neuronal regeneration in the distal stump of full transaction sciatic nerve injury in rats with functional repair. Conduits filled with heparan sulfate and laminin mimetic peptide nanofibers significantly improved electromyography response and promoted neuronal regeneration in a rat model of sciatic nerve defect. In addition, Schwann cells cultured on these nanofibers showed increased viability and significantly enhanced nerve growth factor (NGF) release. Overall, these results suggest that extracellular matrix mimetic peptide nanofibers present a promising treatment option for peripheral nerve injuries.

Visual and brainstem auditory evoked potentials in children with obesity

Diabetic polyneuropathy can be easily diagnosed when the nerve conduction studies are affected. Strength Duration Time (SDTc) reflects nerve excitability properties and was previously used several times to demonstrate the excitability properties of the nerves in the existence of electrophysiologically developed diabetic polyneuropathy. But as we all know, diabetic patients may experience neuropathic symptoms even though their routine nerve conduction studies are normal. SDTc may be useful in this early stages of developing neuropathy. In this study we aimed to evaluate the SDTc properties of diabetic patients in this early preclinic stage. Recently SDTc was commonly studied in the upper extremities but most of the diabetic neuropathies are predominant in the lower extremities. So here we also studied both upper and lower extremities to demonstrate a possible difference.

Importância do período de silêncio cutâneo na fibromialgia e sua relação com as características da doença, distúrbios psicológicos e qualidade de vida dos pacientes

AIMS The aim of our study is to investigate alterations in visual evoked potentials (VEP) and brainstem auditory evoked potentials (BAEP) in children with obesity. METHODS A total of 96 children, with a mean age of 12.1±2.0 years (range 9-17 years, 63 obese and 33 age and sex-matched control subjects) were included in the study. Laboratory tests were performed to detect insulin resistance (IR) and dyslipidemia. The latencies and amplitudes of VEP and BAEP were measured in healthy and obese subjects. RESULTS The VEP P100, BAEP interpeak latency (IPL) I-III and IPL I-V averages of obese children were significantly longer than the control subjects. When the obese group was divided into two subgroups, those with IR and without IR, BAEP wave I, wave III and P100 wave latencies were found to be longer in the group with IR. A statistically significant correlation was observed between BAEP wave I latency, IPL I-V, IPL I-III and the homeostatic model assessment insulin resistance (HOMA IR) index and fasting insulin level. CONCLUSIONS Our findings suggest that VEP and BAEP can be used to determine early subclinical on auditory and visual functions of obese children with insulin resistance.

Increased asymmetric dimethylarginine level after antiepileptic drug treatment may be independent of the changes in plasma homocysteine level.

INTRODUCTION: Cutaneous silent period (CSP) is an inhibitory spinal protective reflex and its afferents consist of A-delta nerve fibers. We aimed to evaluate patients with fibromyalgia (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: Significantly 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.

Asymmetric dimethylarginine may contribute to vascular risk factors in patients receiving antiepileptic drug treatment.

Increased asymmetric dimethylarginine level after antiepi-leptic drug treatment may be independent of the changes in plasma homocysteine level Dear Editor, We have read the recent article by Sniezawska and colleagues with great interest. 1 The authors investigated the frequency of polymorphism in the MTHFR (C677T), MTR (A2756G), and MTHFD1 (G1958A) genes and analysed the levels of homocysteine (Hcy), methionine, asymmetric dimethylarginine (ADMA), and arginine in epileptic patients treated with various antiepileptic drugs (AEDs). They found that AED pharmacotherapy in epileptic patients increases Hcy and ADMA levels. These authors suggested that their study showed an increase in Hcy level accompanied by an increase in ADMA level in epileptic patients receiving AEDs and concluded that hyperhomocysteinemia (HHcy) disrupts the feedback control of Hcy over ADMA. In the discussion, the authors cite Jonasson et al. 2 and Wanby et al. 3 who showed that patients with vascular disease undergoing long-term AED therapy experience HHcy, but the concentration of ADMA does not always increase. Unfortunately these authors did not study Hcy and ADMA levels during the long-term AED therapy. Elevated ADMA levels were first demonstrated in AED-treated epileptic patients in 2009. 4 In this study, the authors investigated the effect of valproic acid (VPA) and carbamazepine (CBZ) monotherapies on plasma levels of ADMA and Hcy and serum levels of folate and vitamin B12 in newly diagnosed epileptic patients. They found that ADMA levels significantly increased after the treatment in both VPA and CBZ groups. Homocysteine levels also increased in both the treatment groups, but the difference was significant only in the VPA group. The correlation between the changes in the ADMA and homocysteine levels was insignificant. Similarly, the difference between the mean ADMA change and mean homocysteine change was insignificant. Thus, these results showed that ADMA plasma levels were not associated with the harmonic changes in homocysteine. Surprisingly, Sniezawska et al. 1 did not cite this article in their study. In our opinion, the lack of discussion of the results of this study may leave readers with an incomplete understanding of the issue. We must consider whether increased ADMA after AED treatment is independent of the changes in plasma Hcy. and MTHFD1 gene polymorphisms compared to homocysteine and asymmetric dimethylarginine concentrations and their meta-bolites in epileptic patients treated with antiepileptic drugs. Hyperhomocysteinaemia is not associated with increased levels of asymmetric dimethylarginine in patients with ischaemic heart disease.