Biomedical subjects

G G Yener

Publications and source records attributed to G G Yener.

6 recordsLinked to original sources

PubMed2006

Increased frontal phase-locking of event-related theta oscillations in Alzheimer patients treated with cholinesterase inhibitors.

This is a pilot study describing event-related oscillations in patients with Alzheimer-type dementia (AD). Theta responses of 22 mild probable AD subjects according to NINCDS-ADRDA criteria (11 non-treated, 11 treated by cholinesterase inhibitors), and 20 healthy elderly controls were analyzed by using the conventional visual oddball paradigm. We aimed to compare theta responses of the three groups in a range between 4-7 Hz at the frontal electrodes. At F(3) location, theta responses of healthy subjects were phase locked to stimulation and theta oscillatory responses of non-treated Alzheimer patients showed weaker phase-locking, i.e. average of Z-transformed means of correlation coefficients between single trials was closer to zero. In treated AD patients, phase-locking following target stimulation was two times higher in comparison to the responses of non-treated patients. The results indicate that the phase-locking of theta oscillations at F(3) in the treated patients is as strong as the control subjects. The F(4) theta responses were not statistically significant between the groups. Our findings imply that the theta responses at F(3) location are highly unstable in comparison to F(4) in non-treated mild AD patients and cholinergic agents may modulate event-related theta oscillatory activities in the frontal regions.

Aged↗

PubMed2001

Phe 84 deletion of the PMP22 gene associated with hereditary motor and sensory neuropathy HMSN III with multiple cranial neuropathy: clinical, neurophysiological and magnetic resonance imaging findings.

Hereditary motor and sensory neuropathy (HMSN) is a heterogeneous group of peripheral neuropathies which are diagnosed on the basis of clinical, electrophysiological and neuropathological findings. Among the hypertrophic demyelinating neuropathies, HMSN III is the most severe. It is often associated with de novo mutations in the genes encoding for peripheral myelin proteins. While peripheral nerve hypertrophy is an expected finding in HMSN III, cranial nerve hypertrophy is exceptional. Here we describe a mutation in the PMP22 gene in a 19-year-old man with infantile onset of sensory motor polyneuropathy without family history and multiple cranial nerve hypertrophy shown by cranial magnetic resonance imaging.

Adult↗

PubMed2001

A case with cerebral thrombosis receiving tamoxifen treatment.

Cerebral sinus thrombosis (CST) is known to be related to a number of underlying aetiologies including otitis media, trauma, pregnancy, birth control pills, tumours, malnutrition, dehydration, haematologic disorders and malignancy (Fishman, 2000; Raizer and Abbott, 2000). We present the case of a patient with breast cancer receiving the antioestrogen drug tamoxifen who developed CST. A 40-year-old female presented as an emergency with a 10-day history of headache and left sided weakness. On questioning her past medical history included a diagnosis of breast cancer 3 years ago treated by radical mastectomy and tamoxifen 20 mg daily. At the time of admission, neurologic examination revealed a mild left sided hemiparesis and a present Babinksi sign. Non-contrast enhanced tomography was normal. Magnetic resonance imaging (MRI) showed thrombosis in the superior sagittal sinus, right lateral sinus and jugular vein in addition venous infarction in the right temporal lobe was present (Figs 1a and b). Routine haematology and biochemistry was normal. Anticoagulation tests, antithrombin III, protein S and C levels were also found to be normal. She was treated with anticoagulation therapy and her hemiparesis improved within 3 days. Control MRI showed the resorption of the venous infarction and resolution of the thrombosis (Fig. 1c).

Adult↗

PubMed1998

Dermatomal and mixed nerve somatosensory evoked potentials in the diagnosis of neurogenic thoracic outlet syndrome.

To evaluate the diagnostic utility of dermatomal and mixed nerve somatosensory evoked potentials (SEPs) in patients with thoracic outlet syndrome (TOS) and to compare their value with routine electrodiagnostic methods, we studied a group of 44 patients with neurogenic TOS and 30 healthy controls. In addition to bilateral median and ulnar SEPs, evoked potentials were recorded after stimulation of C6 and C8 dermatomes from the first and fifth digits, respectively. The patients were classified into 3 groups according to the nature of their clinical condition. The abnormality rate for both ulnar and C8 dermatomal SEPs was 100% in a small group of patients with severe neurological signs like atrophy. In groups of patients with lesser degrees of neurogenic damage, abnormality rates for ulnar and C8 dermatomal SEPs on affected limb(s) were 67 and 50%, respectively. Same abnormality rates were 25 and 18% in patients with only subjective symptoms. In patients with objective neurological signs, the major increase in sensitivity was with electromyography (EMG). Abnormalities of routine nerve conduction studies and F-wave latency were observed in patients with severe neurogenic damage. We concluded that the most useful tests in the diagnosis of neurogenic TOS are needle EMG and ulnar SEPs.

Adult↗

PubMed1996

Quantitative EEG in frontotemporal dementia.

Accurate diagnosis of the major degenerative dementias continues to be problematic. Although diagnostic precision for Alzheimer's disease (AD) approaches 90%, for Frontotemporal dementias (FTD) it has been less than 20%. Previous work has shown that AD patients have both focal and generalized slowing, while in FTD the EEG is normal. We studied 26AD,13FTD and 27 health control subjects with Quantitative Electroencephalography (QEEG). Using only five QEEG measures with stepwise discriminant function analysis, we distinguished the AD from FTD groups each with 84.6% accuracy, and controls (100%) from FTD groups (84.6%) with high accuracy. The most informative QEEG variables for distinguishing FTD and AD were relative power from the temporal region in beta-2 band, and from the parietal region in the theta and alpha and beta-2 bands. These results suggest that QEEG may be helpful in distinguishing subjects with AD from subjects with FTD.

Alpha Rhythm↗

PubMedDate not supplied

Dietary changes, compulsions and sexual behavior in frontotemporal degeneration.

The occurrence of weight gain, sweet and carbohydrate craving, hyposexuality, and compulsions in frontal lobe dementia (FLD) compared to Alzheimer's disease (AD) was evaluated. FLD is a progressive dementia with a high rate of misdiagnosis and therefore better diagnostic criteria for FLD are needed. Fourteen patients meeting research criteria for AD were compared to 14 with suspected FLD. All had cerebral perfusion measured with xenon-133 and imaged with HMPAO using brain-dedicated SPECT. The FLD group showed frontotemporal and AD posterior temporoparietal hypoperfusion. The primary caregivers were queried regarding weight gain, sweet/carbohydrate preference, sexual drive, and compulsions. Differences were compared with Fisher's exact test. The following was found in FLD versus AD: Weight gain in FLD patients amounted to 64% (AD 7%), carbohydrate craving was 79% (vs. 0%) and compulsive behavior 64% (vs. 14%). The differences for these symptoms were statistically significant, whereas for the symptoms increased sexual drive (8 vs. 8%) and reduced sexual drive (54 vs. 23%) no significant difference could be found. In FLD the first symptoms were often dietary changes or hyposexuality. Compulsions were more bizarre and severely disabling in FLD than in AD. Dietary changes, hyposexuality, and disabling compulsions are prominent early symptoms in FLD but not AD. The cause of these symptoms may be due to both frontal and subcortical serotonin loss and dysfunction of the anterior temporal lobes.

Alzheimer Disease↗