QEEG changes during carotid clamping in carotid endarterectomy: spectral edge frequency parameters and relative band power parameters.

Intraoperative monitoring is needed to identify accurately those patients in need of a shunt during carotid endarterectomy. EEG can be used for this purpose, but there is no consensus on the variables to use. Using a database consisting of 149 EEGs recorded from patients during carotid endarterectomy under isoflurane (n=61) or propofol (n=88) anesthesia and who did or did not receive a shunt, the authors investigated which of 16 derivations (common reference, Cz) and 12 parameters (relative and absolute powers and spectral edge frequencies [SEFs]) singly or in combination could best distinguish between the shunt and the nonshunt groups for the two anesthesia regimens. Receiver operating characteristic curves were used to select derivation/parameter combinations for three types of trend computation: (1) values of relative powers and SEFs during clamping (C) only, (2) clamp minus preclamp (baseline) differences (C-B), and (3) C-B differences in absolute logarithmic power (DeltalogP). For both anesthesia regimens, C-B computation distinguished best between the shunt and nonshunt groups. For isoflurane anesthesia, SEF parameters were the best, and for propofol anesthesia the relative power parameters. Discriminant analysis, in which additional derivation/parameter combinations were added, increased the discriminative power of the DeltalogP computation but not of the C or C-B computations. For isoflurane anesthesia, SEF 90% was the best single parameter for distinguishing between patients who did and did not need a shunt and the four best derivations were F3-Cz, P4-Cz, C4-Cz, and F7-Cz. For the propofol anesthesia, the relative power (C or C-B computations) of the delta band was the best and the four best derivations were F8-Cz, T4-Cz, C4-Cz, and F4-Cz.

Accuracy of measurements on digital videostroboscopic images of the vocal folds.

OBJECTIVES: The reliability of objective measurements on digital laryngeal images was investigated. METHODS: The magnitude of the error of measurement of surface areas by visually tracing the outline was determined for three different areas: the area of the lesion and, during vibration, the glottal area on maximal opening of the vocal folds and the glottal area on maximal closing of the vocal folds. RESULTS: The errors in these areas were 10% to 30%. The results suggest that the error is mainly due to the uncertainty of the real outline of areas with a vague boundary. Correction for differences in magnification between two images (posttherapy and pretherapy) is of importance in about 25% to 65% of cases, depending on the area measured. CONCLUSIONS: Only when the magnification ratio is small (less than about +/- 10% from 1.0) may a correction not be necessary.

Correlation between the perceptual rating of speech in Dutch patients with velopharyngeal insufficiency and composite measures derived from mean nasalance scores.

OBJECTIVE: To evaluate the potential clinical use of composite measures derived from mean nasalance scores. PROCEDURE: Speech samples with a normal distribution of phonemes (normal text, NT) and speech samples free of nasal consonants (denasal text, DT) of 43 patients with perceived hypernasality were used. The overall grade of severity, hyperrhinophonia, audible nasal emission, misarticulations associated with velopharyngeal insufficiency and intelligibility were perceptually rated on separate visual analog scales. Mean nasalance scores were computed by the Nasometer for the same speech samples on which the perceptual ratings were performed. From the mean nasalance scores computed for the NT and DT passages the difference and the quotient were calculated. The advantage could be that the derived measures provide some normalization with regard to the performance of the individual speaker. Spearman correlation coefficients were computed between these composite measures and the perceptually rated parameters. The results were compared with the correlation coefficients between the mean nasalance scores and the ratings. SETTING: The Institute of Phoniatrics, Utrecht University Hospital, The Netherlands. RESULTS: The correlations between the composite measures and the perceptual ratings were generally lower than the correlations between mean nasalance scores and the ratings. CONCLUSION: Normalization of the nasalance scores did not enhance the correlation with the perceptual ratings in this study.

Effects of voice therapy on the voice range profiles of dysphonic patients.

In a group of chronically dysphonic patients, a voice range profile, or phonetogram, was recorded before and after receiving voice therapy and again 3 months later. The voice range profiles took a wide variety of shapes. Therefore, only measures that did not depend on a smooth contour could be used to describe changes before and after therapy. The main effect of voice therapy was an enlargement on the side of low frequency and low intensity.

Modality-specific spike identification in simultaneous magnetoencephalography/electroencephalography: a methodological approach.

Epileptiform spikes may have a different morphology and signal-to-noise ratio in simultaneously recorded EEGs and magnetoencephalograms (MEGs) that may lead to differences in the identification of spikes if both the modalities are presented separately. Moreover, there are no criteria for MEG spikes. It is unknown to which extent the visual assessment of MEG data yields consistent and meaningful results. Nineteen patients were selected with mesial temporal lobe epilepsy who underwent whole-head simultaneous MEG/EEG. These data were split into MEG and EEG files and were assessed independently by three observers for the occurrence of spikes. Interobserver kappa values were calculated. A mean kappa value greater than 0.5 was taken as a criterion for the presence of unequivocal spikes. Index cases from the resulting four subgroups were studied further. One patient had unequivocal spikes in both modalities, one in EEG only, one in MEG only, and one did not show any unequivocal spike. Spikes on which at least two observers agreed were then subjected to a template match algorithm to test for equal morphology and distribution. Equal spikes were averaged and electrical and magnetic field maps were plotted. Unequivocal spikes were found in both MEG and EEG in one patient, in MEG only in two patients, in EEG only in two patients, and no spikes in either modality were seen in 14 patients. In the four index patients, MEG showed 50 to 80% more spikes than EEG. After averaging identical consensus spikes, MEG spikes revealed a concomitant spike in the EEG, but the reverse was not always true. Even in the patient with MEG and EEG spikes that met all selection criteria, simultaneous field maps showed unexpected inconsistencies. In most patients with mesial temporal lobe epilepsy, there are no unequivocal spikes during MEG/EEG. In some cases, however, experienced electroencephalographers can identify MEG spikes reliably. Because of a better signal-to-noise ratio, more spikes could be identified in MEG than in EEG. Simultaneous MEG/EEG recordings do not simply ensure the best of both, but one modality may improve the identification of spikes in the other. In addition, different aspects of a complex source can be revealed. Our three-step approach to combined data ensures a reproducible selection of spikes for source modeling.

High embolic rate early after carotid endarterectomy is associated with early cerebrovascular complications, especially in women.

PURPOSE: The aim of this study was to evaluate the relationship between the rate of emboli (ER), as detected with transcranial Doppler scan (TCD) monitoring during and shortly after carotid endarterectomy (CEA), and early cerebrovascular complications (CVC). MATERIALS AND METHODS: One-hunderd eighty-five consecutive patients underwent 203 CEAs with general anesthesia at the Sint Lucas Andreas Hospital. Inclusion criteria included adequate TCD monitoring during the operation and for at least 10 minutes in the recovery room. Fifteen patients were excluded because of inadequate TCD monitoring. To prevent statistical bias, only data from the first operation of those patients who underwent bilateral CEA were included. The study group thus consisted of 170 patients (113 men, 57 women) with a mean age of 67 years (range, 45 to 83 years). The monitored TCD signals were stored on tape for offline analysis. ERs during dissection, wound closure, and the postoperative period shortly after arrival in the recovery room were studied. Preoperative and early postoperative neurologic examination, including grading with the modified Rankin scale, was performed by the same board-certified neurologist. RESULTS: A CVC occurred in 10 patients (5.9%). Five minor strokes (2.9%) and three major strokes (1.8%) occurred, one with a fatal outcome (0.6%). Two patients (1.2%) had transient ischemic attacks. Median ERs for the three periods studied were significantly different (postoperative period, 0.3/min; dissection, 0.03/min; wound closure: 0/min; Friedman, P <.005). ERs were significantly higher in the CVC group but only during wound closure (P =.0003) and the postoperative period (P <.0001). Women had significantly more CVCs than men (14% versus 2.7%; P <.02) and, during the postoperative period, had a significantly higher median ER (0.70/min) than men (0.25/min) (P <.002). High ERs during dissection in two men were associated with CVC. An ER of 0.9/min or more during the postoperative period was significantly correlated with CVC (P <.0001; odds ratio, 64.6; 95% CI, 3.7 to 1128). CONCLUSION: Especially during the postoperative period, high ER is associated with early CVC. Women have a higher ER than men in this period. If the ER is 0.9/min or more during the postoperative period, there appears to be at least a nearly four-fold increased risk of CVC.

The correlation between nasalance and a differentiated perceptual rating of speech in Dutch patients with velopharyngeal insufficiency.

OBJECTIVE: The correlation between the nasalance score and the perceptual rating of several aspects of speech of speakers with velopharyngeal insufficiency (VPI) by six speech-language pathologists was evaluated. PROCEDURE: The overall grade of severity, hypernasality, audible nasal emission, misarticulations, and intelligibility were rated on visual analog scales. Speech samples with a normal distribution of phonemes (normal text [NT]) and those free of nasal consonants (denasal text [DT]) of 43 patients with VPI were used. Mean nasalance scores were computed for the speech samples, and Spearman correlation coefficients were computed between the mean nasalance score and the five parameters of the differentiated rating. SETTING: The Institute of Phoniatrics, Utrecht University Hospital, The Netherlands. RESULTS: The correlation coefficient between the mean nasalance and the perceptual rating of hypernasality ranged among judges from .31 to .56 for NT speech samples and .36 to .60 for DT speech samples. Only small differences were found between speech pathologists with and without expertise in cleft palate speech. The rating of the overall grade of severity appeared to correlate quite well with the rating of the intelligibility (r(NT) = .77, r(DT) = .79). Lower correlation coefficients, ranging from .34 to .71, were found between overall grade of severity and hypernasality, audible nasal emission, and misarticulations. CONCLUSIONS: A low correlation between the nasalance and the perceptual rating of hypernasality was found. The parameter overall grade of severity appeared to be determined mainly by the parameter intelligibility. Expertise in rating of cleft palate speech does not guarantee a high correlation between instrumental measurement and perceptual rating.

Subtle involvement of the sympathetic nervous system in amyotrophic lateral sclerosis.

The literature on the involvement of the autonomic nervous system (ANS) in amyotrophic lateral sclerosis (ALS) is conflicting. We therefore investigated several aspects of autonomic function, namely muscle sympathetic nerve activity (MSNA), blood pressure, cardiac function (electrocardiogram; ECG), and respiration in 16 patients with sporadic ALS and in 12 age-matched healthy volunteers, both at rest and during sympathoexcitatory stimulation. We measured MSNA by provoking venous pooling during short-lasting lower body negative pressure (LBNP) and during the cold pressor test (CPT). To assess the vagal (baroreflex) control of heart rate (HR), we measured spontaneous baroreflex sensitivity (BRS). To assess the involvement of the ANS beyond the cardiovascular system, we measured the sympathetic skin response (SSR). The stand-up test showed that none of the subjects had orthostatic intolerance. In comparison with the control group, the ALS patients had an increased HR and a decreased BRS at rest, and a reduced MSNA response to LBNP. The CPT response was normal and the total MSNA at rest did not differ significantly from that of controls. The latencies of the palmar and plantar SSR were prolonged, and in 3 ALS patients there was no plantar SSR. The results indicate that the sympathetic nervous system shows subtle abnormalities in ALS, predominantly sympathetic overactivity. They also point to the involvement of the preganglionic sympathetic column as the cause of the higher sympathetic activity and the absence of SSR. The higher sympathetic activity is postulated to be due to changes in modulation of the sympathetic system, whereas the absence of the SSR is probably caused by disruption of the reflex pathway.