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Biomedical subjects

C Yiannikas

Publications and source records attributed to C Yiannikas.

46 records · Page 3Linked to original sources
PubMed1983

Visual evoked potentials in the detection of subclinical optic toxic effects secondary to ethambutol.

In 14 patients with tuberculosis treated with ethambutol hydrochloride, pattern-reversal visual evoked potentials (VEPs) were recorded to monocular, whole-field stimulation before the commencement of treatment and one month and three months subsequently. In six subjects, the VEPs showed changes in the latency and amplitude of the P100 component at the one- or three-month interval. In three cases, the VEP changes reversed after cessation of treatment. In five of the six cases, changes were not associated with a change in visual function, as measured by clinical neuro-ophthalmologic examination. Our findings confirm the usefulness of VEPs in the detection of subclinical optic nerve disease and suggest their use in routine monitoring of ocular function in patients treated with ethambutol.

Adolescent↗
PubMed1983

The investigation of traumatic lesions of the brachial plexus by electromyography and short latency somatosensory potentials evoked by stimulation of multiple peripheral nerves.

A study of 10 patients with brachial plexus trauma was performed to determine whether the diagnostic accuracy of sensory evoked potentials (SEPs) may be improved by using stimulation of multiple peripheral nerves (median, radial, musculocutaneous and ulnar). In addition, the relative advantages of SEPs and peripheral electrophysiological studies were considered. SEP patterns following most common brachial plexus lesions were predictable. Injuries to the upper trunk affected the musculocutaneous and radial SEPs predominantly. Lower trunk or medial cord lesions primarily affected ulnar SEPs. Diffuse brachial plexus lesions affected SEPs from all stimulation sites. In the majority of cases, the necessary information was obtainable from conventional EMG: however, for lesions involving the upper segments only, SEP techniques were more useful. It is suggested that selective SEPs from appropriate peripheral nerves when interpreted in combination with conventional EMG may add useful additional information.

Adolescent↗
PubMed1983

Somatosensory evoked responses in the diagnosis of thoracic outlet syndrome.

A study was made of 11 patients with cervical rib, and one patient with Klippel-Fiel syndrome and enlarged transverse processes to determine whether evoked potentials recorded from both Erb's points and the cervical spine in response to median and ulnar nerve stimulation provided information additional to that obtained by EMG and peripheral conduction studies. It was found that in seven patients who had pain and paraesthesias but no objective neurological signs both the peripheral and central conduction studies were within normal limits. By contrast, of five patients who had objective signs, conventional EMG and conduction studies were abnormal in three patients, but abnormalities of the evoked potentials obtained from ulnar nerve stimulation were obtained in all five patients. It is suggested that this application of evoked potential estimation is a useful addition to the more conventional peripheral investigations.

Adolescent↗
PubMed1983

Peripheral neuropathy associated with polycythemia vera.

Nerve conduction studies were performed on 26 patients with polycythemia vera, 11 of whom had sensory symptoms in the extremities and 3 of whom had clinical signs of peripheral neuropathy. There was significant impairment of sensory conduction in the ulnar and sural nerves and mild slowing of motor conduction in the lateral popliteal nerve. Sural nerve biopsies were performed on three patients. The pathological findings, including teased fiber studies, were consistent with mild chronic axonal degeneration. There is an association between polycythemia vera and peripheral neuropathy.

Adult↗
PubMed1981

Nitrofurantoin neuropathy.

Four cases of severe peripheral neuropathy directly attributable to nitrofurantoin are reported. The neuropathy was not dose-related and not necessarily associated with abnormal renal function. Recovery was slow, and neither severity nor recovery was related to the total dose of the drug. The pathological changes seen on light microscopy and electron microscopy were those of acute, severe axonal degeneration. It is emphasised that nitrofurantoin is a neurotic drug and should not be prescribed to the elderly not to anyone with impairment of renal function.

Aged↗
PubMed1979

Clinical evaluation of computed tomographic scanning.

Computed tomographic (CT) head scans were performed on 100 patients in a neurology ward. The CT scan was diagnostic in 67 patients and suggestive in a further three patients. Computed tomographic scans were most likely to be diagnostic in patients whose symptoms at presentation could be classified as "traumatic intracranial lesion", "space-occupying lesion", "acute cerebrovascular lesion", "dementia", and "epileptic disorder", and much less likely to be diagnostic if a patient presented differently. In all cases where the CT scan was diagnostic. It was considered that, had a CT scan not been available, alternative tests such as nuclear scan, cerebral angiography or pneumoencephalogram (PEG) would have been performed and would also have been diagnostic; no impact of the CT scan on diagnosis, therapy or patient outcomes was documented. However, in patients who received a CT scan, there was a 91% reduction in the PEGs, 85% reduction in cerebral angiograms, a reduction of 73% in nuclear scans and 31% in electroencephalograms. Computed tomographic scanning costs no more than the tests it replaces in the clinical setting studied, and offers significant advantages in patient comfort and safety.

Brain Diseases↗
PubMedDate not supplied

The relationship between quantified EEG and skin conductance level.

Electroencephalographic measures (EEG) and skin conductance level (SCL) respectively reflect cerebral cortical activity and sympathetic autonomic activity. Such central and autonomic activities associated with arousal generally have been studied separately, despite their potential to reflect complementary dimensions of reticular-thalamo-hypothalamo-cortical activating networks. In this study, we examined the relationship between cortical (19 EEG sites) and autonomic (SCL) activities recorded simultaneously in 10 normal adults. Two second pre-stimulus EEGs and SCLs were assessed from an habituation paradigm which presented 22 trains of 7 tones in an 'ignore' condition. The mean SCLs of the epochs across subjects showed an initial rise (sensitization) followed by an exponential decline (habituation). Although EEG associated with the tones did not demonstrate such a distinct profile, EEG total power and band powers (beta, alpha and theta) associated with the trains showed a systematic increasing response profile. In the group data the mean SCLs within trains showed a significant correlation with alpha and beta band powers. Finer EEG band analyses indicated that beta 3 at Fz and alpha 2 at Cz showed the strongest separate linear correlations with SCL. beta 3 and alpha 1 at Fz were found to jointly covary with SCL. The findings indicate a substantive relationship between measures of cerebral function and autonomic arousal.

Acoustic Stimulation↗
PubMedDate not supplied

The interaction between sex and click polarity in brain-stem auditory potentials evoked from control subjects of Oriental and Caucasian origin.

Brain-stem auditory evoked potentials (BAEPs) were performed on 30 male and 30 female young normal Oriental subjects, using both condensation and rarefaction stimulation. The effects of sex and click polarity on the BAEP latencies and amplitudes were studied. Females had shorter absolute and interpeak latencies and higher absolute amplitudes than the males. These sex-related BAEP differences were independent of the click polarity. Rarefaction clicks produced shorter wave I latency and longer I-III interpeak latency, but the differences were significant in the female only. The polarity-related BAEP amplitude differences were essentially independent of the sex. BAEPs performed on 60 sex- and age-matched young Caucasian subjects produced similar results. The importance of establishing control BAEP values according to the sex and click polarity is emphasised.

Acoustic Stimulation↗