Optical wireless cochlear implants.

In the present contribution, we introduce a wireless optical communication-based system architecture which is shown to significantly improve the reliability and the spectral and power efficiency of the transcutaneous link in cochlear implants (CIs). We refer to the proposed system as optical wireless cochlear implant (OWCI). In order to provide a quantified understanding of its design parameters, we establish a theoretical framework that takes into account the channel particularities, the integration area of the internal unit, the transceivers misalignment, and the characteristics of the optical units. To this end, we derive explicit expressions for the corresponding average signal-to-noise-ratio, outage probability, ergodic spectral efficiency and capacity of the transcutaneous optical link (TOL). These expressions are subsequently used to assess the dependence of the TOL's communication quality on the transceivers design parameters and the corresponding channels characteristics. The offered analytic results are corroborated with respective results from Monte Carlo simulations. Our findings reveal that the OWCI is a particularly promising architecture that drastically increases the reliability and effectiveness of the CI TOL, whilst it requires considerably lower transmit power when compared to the corresponding widely-used radio frequency (RF) solution.

Comparison of the volatile composition in thyme honeys from several origins in Greece.

Thyme honey is the most appreciated unifloral Greek honey in Greece as well as around the world. In an effort to investigate the headspace composition of this type of honey, 28 samples were analyzed by means of solid-phase microextraction coupled to a gas chromatography-mass spectrometry system. The botanical origin of the samples was ascertained by pollen analysis, and samples displayed relative frequencies of thyme pollen between 18 and 41%. A total of 62 compounds were isolated, and phenylacetaldehyde was the most abundant (32.9% of the total peak area). Possible botanical markers are 1-phenyl-2,3-butanedione (13.4%), 3-hydroxy-4-phenyl-2-butanone, 3-hydroxy-1-phenyl-2-butanone (14.7%), phenylacetonitrile (4.8%), and carvacrol (0.9%), since these compounds are found only in thyme honey. Additionally, high proportions of phenylacetaldehyde are also characteristic ( F = 12.282, p < 0.001). The average concentrations of seven compounds were significantly different ( p < 0.05), namely phenylacetaldehyde, acetophenone, octanoic acid, carvacrol, phenylethyl alcohol, nonanal, and hexadecane. Applying principal component analysis to the data, six components were extracted, explaining 85.4% of the total variance. The first component explained 46.2% of the total variance and was positively correlated to phenylacetaldehyde, nonanoic acid, acetophenone, decanoic acid, benzaldehyde, phenylacetonitrile, isophorone, and nonanal. The extracted components were used as variables to the discriminant analysis, which showed good discrimination, especially for samples from Crete. A leave-one-out classification showed 85.7% of cross-validated grouped cases correctly classified. These results are promising to establish a discrimination model for these geographical regions. This is crucial for local beekeeper corporations on their effort to produce honey with geographical origin label.

FT-Raman spectroscopic simultaneous determination of fructose and glucose in honey.

A new method for mass percentage determination of fructose and glucose based on FT-Raman spectroscopy is evaluated with a standard HPLC-based method. FT-Raman spectra manipulation is done via the spectrometer software, and a PLS (partial least squares) method is developed with the TQ Analyst software (Ver 1. 1a). The simultaneous quantitative determination uses an input range from 1700 to 700 cm(-1) without correction or baseline factors. The standards used in the PLS method are honey samples previously analyzed by HPLC to obtain their mass percentage concentrations in fructose and glucose. The returned results are statistically tested with those of the HPLC method. Both methods appear to score equally in terms of reproducibility. The honey content of the two sugars in total was found up to 40-74%. The honey samples content in fructose and glucose was determined by HPLC (24.1-42.9% and 16.2-33.1%, respectively) and FT-Raman (24.0-40.8% and 21.1-32.2%, respectively).

Clinical characteristics of the alpha-synuclein mutation (G209A)-associated Parkinson's disease in comparison with other forms of familial Parkinson's disease in Greece.

An Ala53Thr mutation of the alpha-synuclein has been recently identified as a rare cause of familial Parkinson's disease (fPD). In the present study, the clinical characteristics of Parkinson's disease (PD) patients with Ala53Thr alpha-synuclein mutation (alpha-synPD) were compared with fPD patients without any known mutation. An investigator blinded to the results of the genetic analysis examined 15 alpha-synPD patients and 43 consecutive fPD patients. Demographic data, age at onset of the illness, duration of the disease and modality of presentation were collected. Segregation ratios for both sexes in individuals at risk of developing alpha-synPD were estimated. The Unified Parkinson's disease rating scale (UPDRS) was also completed. The 15 alpha-synPD patients were matched for duration of the disease and age at onset with 15 of the 43 fPD patients (MfPD). Comparisons were also made between 14 patients belonging to three multicase families with patterns of inheritance similar to alpha-synPD. The alpha-synPD patients were significantly younger (mean difference 11.8 years) and showed the first sign of the disease earlier in life (mean difference 12.7 years) as compared with the fPD patients. Tremor at onset was present in only one (6.7%) of the alpha -synPD patients compared with 18 (41.9%) of the fPD patients (P = 0.01). At the time of examination rigidity, postural instability, orthostatic hypotension and the overall clinical severity did not differ significantly either between alpha-synPD and fPD or between alpha-synPD and MfPD groups. Nevertheless, some clinically relevant trends concerning the psychiatric symptoms and complications of therapy were recognized. The overall clinical severity and the progression of the disease in patients with alpha-synPD did not differ from that of the fPD patients. The alpha-synPD patients presented the illness at a younger age and also had lower prevalence of tremor when compared with the fPD patients.

Peripheral sensory neuropathy associated with short-term oral acitretin therapy.

A 57-year-old female patient with widespread chronic plaque psoriasis and a 32-year-old male patient with severe oral lichen planus are reported, who developed sensory symptoms in the extremities 3 and 4 months after the onset of oral acitretin therapy, respectively. Both patients showed clinical and electrophysiological evidence of a sensory peripheral neuropathy, which completely resolved 2 and 2.5 years after discontinuation of oral acitretin administration, respectively.

Sensorimotor polyneuropathy after a three-month oral acitretin therapy.

We report a patient with chronic plaque psoriasis who developed clinical and electrophysiologic features of polyneuropathy affecting motor and sensory fibers in upper and lower extremities after three months of treatment with oral acitretin. Drug withdrawal resulted in a complete clinical recovery and normalization of all electrophysiologic abnormalities within two months.

Stiff-person syndrome associated with oral isotretinoin treatment.

We describe a patient with severe nodulocystic acne who developed disabling muscle stiffness and painful superimposed spasms of the neck, back and upper limbs 10 days after the onset of oral isotretinoin treatment. The muscle hyperactivity condition, which revealed the clinical and electromyographic features of the stiff-person syndrome, gradually resolved 2 weeks after drug withdrawal.

Family history of stroke in stroke types and subtypes.

Many studies have provided data showing that family history of stroke (FHS) is associated with an increased risk of stroke. The association of the FHS with the various stroke subtypes has not been adequately studied. The purpose of this study was to assess the association of the FHS with the two major stroke types (cerebral haematomas and ischaemic strokes) and the four stroke subtypes (cardioembolic, large artery disease, small artery disease, and undetermined) in a Greek population. The FHS was obtained from 421 consecutive acute stroke patients and from 239 matched control subjects. Positive FHS was observed in 49% of all stroke patients compared with 28% of the control subjects [adjusted OR=2.06 (95% confidence intervals (CI) 1.42-3.00)]. Haematomas, ischaemic strokes, and from the ischaemic strokes, both large and small artery disease strokes were strongly associated with positive FHS compared with the control subjects [adjusted OR=2.06 (95% CI 9-3.04), 2.07 (95% CI 1.09-3.91), 2.05 (95% CI 1.24-3.38), and 2.76 (95% CI 1.55-4.91), respectively]. There was no difference between maternal and paternal heritable contribution.In conclusion, FHS was found in this study to be an independent risk factor for all strokes combined, for each stroke type, and for the large and small-artery disease stroke subtypes, but not for the cardioembolic and undetermined stroke subtypes.

Carpal tunnel syndrome and hand configuration.

The likelihood that hand configuration is related to the development of carpal tunnel syndrome (CTS) was examined in this study. Based on neurophysiological criteria, 50 female subjects with CTS and 50 healthy female controls were selected and their external hand dimensions were measured. Our results showed that the palm length and third digit length were significantly shorter and the palm width larger in the subjects with CTS compared with controls. Regression analysis demonstrated that the hand ratio [(palm + third digit length)/palm width] was significantly correlated with median nerve conduction measurements. The hand ratio may be a simple and useful predictive measurement in determining the tendency for CTS.

Two episodes of leukoencephalitis associated with recombinant hepatitis B vaccination in a single patient.

Cases of central nervous system demyelination have been reported after recombinant hepatitis B vaccination, but no causal link has been clearly demonstrated. We present the first case report involving the occurrence of 2 episodes of leukoencephalitis in a previously healthy patient after vaccination and rechallenge with hepatitis B vaccine.

Clinical phenotype in patients with alpha-synuclein Parkinson's disease living in Greece in comparison with patients with sporadic Parkinson's disease.

OBJECTIVE: An Ala53Thr mutation of the alpha-synuclein gene has been recently identified as a rare cause of autosomal Parkinson's disease (PD). The clinical characteristics of 15 patients with PD living in Greece with the Ala53Thr alpha-synuclein mutation (alpha-synPD) were compared with patients with sporadic Parkinson's disease (sPD). METHODS: An investigator, blind to the results of the genetic analysis, examined 15 patients with alpha-synPD and 52 consecutive patients with sPD. Demographic data, age at onset of the illness, modality of presentation, and duration of PD were collected. The unified Parkinson's disease rating scale, the Hoehn and Yahr scale, and the Schwab-England scale were completed. The patients with alpha-synPD were matched for duration of disease with 32 of the 52 patients with sporadic PD (MsPD group). RESULTS: Patients with the alpha-synuclein mutation were significantly younger (mean 7.6 years), showed the first sign of the disease significantly earlier in life (mean 10.8 years), and had significantly longer duration of the disease compared with patients with sPD. Tremor at onset of the disease was present in only one (6.7%) of the patients with alpha-synPD, whereas it was present in 32 (61.5%) of the patients with sPD (p=0.0006). During the course of the disease one patient in the alpha-synPD group went on to develop tremor compared with six patients in the sPD group. Rigidity, bradykinesia, postural instability, orthostatic hypotension, intellectual impairment, depression, complications of therapy, and clinical severity of the disease at the time of examination did not differ significantly between patients with alpha-synPD and those with sPD, or between patients with alpha-synPD and the MsPD group. CONCLUSION: The younger age at onset of the illness, the much lower prevalence of tremor, and the longer duration of the disease characterise the clinical phenotype in this sample of patients with alpha-synPD. The other symptoms and signs of the illness did not seem to differentiate the patients with alpha-synPD from those with sPD.

Segmental myoclonus as the sole manifestation of a choroid plexus papilloma in the posterior fossa. Case report.

The authors describe the case of a 22-year-old woman with involuntary contractions of the sternocleidomastoid and trapezius muscles that resulted in turning movements of the head. The jerks displayed the clinical and neurophysiological characteristics of segmental myoclonus (SM) restricted to muscles supplied bilaterally by the first four cervical segments. Magnetic resonance imaging disclosed a tumor in the midline above the cisterna magna that was later histologically proven to be a choroid plexus papilloma. The patient's involuntary movements did not extend to other muscle groups or, in particular, to the palate, as one might have expected in the case of brainstem lesions. Myoclonus was the sole clinical manifestation of the tumor in this patient; other signs and symptoms invariably reported in other cases of posterior fossa papilloma, such as increased intracranial pressure or cranial nerve palsies, were absent. Release from suprasegmental control is suggested as a possible pathophysiological mechanism in this case of SM.

Effects of short-term oral acitretin therapy on peripheral nerve function: a prospective neurological and neurophysiological study.

The aim of the present prospective study was to substantiate possible side effects of short-term oral acitretin therapy (1 mg/kg/day) on peripheral nerve function of 13 patients with severe keratinization disorders. Clinical neurological examination before and 1 and 3 months after onset of treatment was unremarkable in all patients; however, a significant alteration of one or more neurophysiological, predominantly sensory, parameters was demonstrated in 3 out of 13 patients (23%) after 1 month and in 9 out of 13 (69%) after 3 months of oral acitretin therapy. These findings indicate that oral acitretin might be capable of causing a dysfunction of predominantly sensory nerve fibres in some individuals. Although in the investigated patients this dysfunction remained subclinical, it seems reasonable to suggest that neurological and neurophysiological evaluation of peripheral nerves should be added to the list of investigations that are routinely performed in patients receiving oral acitretin.

Neurophysiologic studies in peripheral arterial disease.

The purpose of the study was to compare the electrophysiological parameters (nerve conduction studies and quantitative electromyography [EMG]) between patients with chronic peripheral arterial disease (PAD) and normal control subjects. Forty patients with PAD and 30 control subjects (40 legs) were evaluated clinically and electrophysiologically using previously described methods. The amplitude of compound muscle action potentials (CMAPs) and the motor conduction velocities (MCVs) of peroneal and tibial nerve for most patients with PAD were within normal limits but compared with those of the controls, it was found that the peroneal and tibial MCVs as well as the amplitude of sural nerve were significantly decreased. The EMG testing of patients with PAD and controls of the anterior tibialis and the gastrocnemius muscle did not show evidence of denervation or myopathic abnormalities. However, the mean amplitude and duration of both muscles were significantly larger compared with the controls. Routine electrophysiological studies are not the appropriate (sensitive enough) tests for detecting peripheral nerve or muscle dysfunction associated with PAD.

Early diagnosis of carpal tunnel syndrome: comparison of sensory conduction studies of four fingers.

Sensory studies of four fingers were performed on 72 patients with early (distal motor latency <4.2 ms) carpal tunnel syndrome (CTS) and on 43 control subjects. Results demonstrate that sensory studies of digit 4 yields the highest sensitivity (88%) for diagnosis of early CTS. The sensitivity of digit 1, digit 2, and digit 3 was 61%, 22%, and 50%, respectively.

Nicotine, caffeine and alcohol use in high- and low-dose benzodiazepine users.

Cigarette smoking, coffee and alcohol use were investigated prospectively in 37 high-dose benzodiazepine (BZD) regular users (HDRU), 87 low-dose BZD regular users (LDRU), 50 low-dose BZD occasional users (LDOU) and in 37 non-BZD users (control subjects). The frequency of smokers was significantly greater in the HDRU than in the other three groups studied. Also, the HDRU consumed a significantly greater number of cigarettes and dose of caffeine per day than the other subjects investigated. Also, alcohol dependence was significantly more frequent in the HDRU. Regression analysis showed a significant positive correlation between the BZD dose and both the cigarettes and the caffeine consumed per day. The findings suggest that BZD should be prescribed with caution in individuals who are heavy smokers or are consuming large amounts of coffee and alcohol.