Zoran Đogaš

Excitability of contralateral and ipsilateral projections of corticobulbar pathways recorded as corticobulbar motor evoked potentials of the cricothyroid muscles

OBJECTIVE The objective of this study was to evaluate the excitability of contralateral and ipsilateral corticobulbar pathways, using the methodologies of navigated transcranial magnetic stimulation (nTMS) and transcranial electrical stimulation (TES). METHODS In 11 healthy subjects, the primary motor cortex (M1) for laryngeal muscles was mapped with nTMS in both hemispheres and the corticobulbar motor evoked potentials (CoMEPs) were recorded from the right cricothyroid muscle. In 15 patients undergoing left craniotomy, CoMEPs were obtained from cricothyroid muscles bilaterally, using TES over C3/Cz and C4/Cz. RESULTS In five out of 11 healthy subjects, both contralateral and ipsilateral CoMEPs were recorded from the right cricothyroid muscle. In eight out of 15 patients, contralateral and ipsilateral CoMEPs were elicited with TES over C3/Cz, while in five out of 15 patients contralateral and ipsilateral CoMEPs were elicited with TES over C4/Cz. Contralateral CoMEP amplitude responses were significantly larger compared to ipsilateral CoMEP amplitudes in both groups. CONCLUSION We obtained significantly larger amplitude responses of contralateral CoMEPs from cricothyroid muscles compared to ipsilateral CoMEP amplitude using nTMS in healthy subjects and TES in patients. This confirms the bilateral nature of corticobulbar pathway projections for laryngeal muscles, with contralateral domination. SIGNIFICANCE These findings will influence recording of CoMEPs during preoperative and intraoperative mapping of M1 for laryngeal muscle representation, and they facilitate the pathophysiologic research of motor speech disorders.

Emigration-related attitudes of the final year medical students in Croatia: a cross-sectional study at the dawn of the EU accession.

Aim To investigate the emigration-related attitudes of final year medical students in Croatia at the dawn of the EU accession in 2013. Methods All final-year medical students at four Croatian medical schools (Zagreb, Rijeka, Split, and Osijek) were invited to participate in a cross-sectional survey on emigration attitudes. Results Among 260 respondents (response rate 61%), 90 students (35%) reported readiness for permanent emigration, expecting better quality of life (N = 22, 31%), better health care organization (N = 17, 24%), more professional challenges (N = 10, 14%), or simply to get a job (N = 8, 11%), while the least common expectation were greater earnings (N = 7, 10%). The most common target countries were Germany (N = 36, 40%), USA and Canada (N = 15, 17%), and UK (N = 10, 11%). In a multivariate analysis, readiness for permanent emigration was associated with an interest in undertaking a temporary training abroad (odds ratio [OR] 6.87; 95% confidence interval [CI] 2.83-16.72), while the belief that the preferred specialty could be obtained in Croatia appeared protective against emigration (OR 0.26; 95% CI 0.12-0.59). Conclusion Despite shortages of health care workers in Croatia, the percentage of students with emigration propensity was rather high. Prevalent negative perception of the Croatian health care and recent Croatian accession to the EU pose a threat of losing newly graduated physicians to EU countries.

A novel approach for monitoring writing interferences during navigated transcranial magnetic stimulation mappings of writing related cortical areas.

BACKGROUND It has recently been shown that navigated repetitive transcranial magnetic stimulation (nTMS) is useful in preoperative neurosurgical mapping of motor and language brain areas. In TMS mapping of motor cortices the evoked responses can be quantitatively monitored by electromyographic (EMG) recordings. No such setup exists for monitoring of writing during nTMS mappings of writing related cortical areas. NEW METHOD We present a novel approach for monitoring writing during nTMS mappings of motor writing related cortical areas. COMPARISON WITH EXISTING METHOD(S) To our best knowledge, this is the first demonstration of quantitative monitoring of motor evoked responses from hand by EMG, and of pen related activity during writing with our custom made pen, together with the application of chronometric TMS design and patterned protocol of rTMS. RESULTS The method was applied in four healthy subjects participating in writing during nTMS mapping of the premotor cortical area corresponding to BA 6 and close to the superior frontal sulcus. The results showed that stimulation impaired writing in all subjects. The corresponding spectra of measured signal related to writing movements was observed in the frequency band 0-20 Hz. Magnetic stimulation affected writing by suppressing normal writing frequency band. CONCLUSION The proposed setup for monitoring of writing provides additional quantitative data for monitoring and the analysis of rTMS induced writing response modifications. The setup can be useful for investigation of neurophysiologic mechanisms of writing, for therapeutic effects of nTMS, and in preoperative mapping of language cortical areas in patients undergoing brain surgery.

Reduced evoked motor and sensory potential amplitudes in obstructive sleep apnea patients

It is unknown to what extent chronic intermittent hypoxaemia in obstructive sleep apnea causes damage to the motor and sensory peripheral nerves. It was hypothesized that patients with obstructive sleep apnea would have bilaterally significantly impaired amplitudes of both motor and sensory peripheral nerve‐evoked potentials of both lower and upper limbs. An observational study was conducted on 43 patients with obstructive sleep apnea confirmed by the whole‐night polysomnography, and 40 controls to assess the relationship between obstructive sleep apnea and peripheral neuropathy. All obstructive sleep apnea subjects underwent standardized electroneurographic testing, with full assessment of amplitudes of evoked compound muscle action potentials, sensory neural action potentials, motor and sensory nerve conduction velocities, and distal motor and sensory latencies of the median, ulnar, peroneal and sural nerves, bilaterally. All nerve measurements were compared with reference values, as well as between the untreated patients with obstructive sleep apnea and control subjects. Averaged compound muscle action potential and sensory nerve action potential amplitudes were significantly reduced in the nerves of both upper and lower limbs in patients with obstructive sleep apnea compared with controls (P < 0.001). These results confirmed that patients with obstructive sleep apnea had significantly lower amplitudes of evoked action potentials of both motor and sensory peripheral nerves. Clinical/subclinical axonal damage exists in patients with obstructive sleep apnea to a greater extent than previously thought.

No difference in the intention to engage others in academic transgression among medical students from neighboring countries: a cross-national study on medical students from Bosnia and Herzegovina, Croatia, and Macedonia

Aim To asses if the level of intention to engage others in academic transgressions was comparable among medical students from five schools from neighboring Southern-European countries: Croatia, Bosnia and Herzegovina, and Macedonia; and medical students from western EU studying at Split, Croatia. Methods Five medical schools were surveyed in 2011, with ≥87% of the targeted population sampled and a response rate of ≥76%. Students’ intention to engage a family member, friend, colleague, or a stranger in academic transgression was measured using a previously validated the Intention to Engage Others in Academic Transgression (IEOAT) questionnaire and compared with their intention to ask others for a non-academic, material favor. Data on students’ motivation measured by Work Preference Inventory scale, and general data were also collected. Multiple linear regression models of the intention to engage others in a particular behavior were developed. Results The most important determinants of the intention to engage others in academic transgression were psychological factors, such as intention to ask others for a material favor, or students’ motivation (median determinant’s β of 0.18, P ≤ 0.045 for all), whereas social and cultural factors associated with the country of origin were either weak (median β of 0.07, P ≤ 0.031) or not relevant. A significant proportion of students were aware of the ethical violations in academic transgressions (P ≤ 0.004 for all transgressions), but a large proportion of students also perceived academic cheating as a collective effort and were likely to engage people randomly (P ≤ 0.001 for all, but the most severe transgression). This collective effort was more pronounced for academic than non-academic behavior. Conclusion Culture differences among neighboring Southern-European countries were not an important determinant of the intention to engage others in academic cheating.