Aspiration: a potential complication to vagus nerve stimulation

PURPOSE: Vagus nerve stimulation (VNS) is reported to reduce the frequency of seizures in children and adults without causing serious side effects. However, clinical observation of swallowing difficulties in 2 children treated with VNS made further investigation necessary. METHODS: Seven patients aged 4-18 years and treated with VNS for 6-14 months were investigated with videoradiography during barium swallow. The children performed 5-30 barium swallow investigations with the VNS device turned off, running as programmed, or set at continuous stimulations. The degree of aspiration was scored from 0 to 3. RESULTS: In 5 of 7 children, of whom reported transient swallowing difficulties, no change in the degree of aspiration was noted. The 2 children with swallowing difficulties, however. showed increased aspiration score when the stimulator was set at continuous stimulations. In 1 the score also appeared to increase with the VNS running as programmed (p > 0.05). Both children had severe mental and motor disabilities. CONCLUSIONS: Before and during VNS treatment patients should be evaluated with regard to swallowing problems. There needs to be an easy way to turn the device on and off to avoid aspirations, a hazardous and potentially life-threatening complication of VNS.     

Bradycardia induced by intravascular versus direct stimulation of the vagus nerve

Ricin is a heterodimeric cytotoxin composed of RTB, a galactose binding lectin, and RTA, an enzymatic N-glycosidase. The toxin is endocytosed, and after intracellular routing, RTA is translocated to the cytoplasm where it inactivates ribosomes resulting in a loss of host cell protein synthesis and cell death. We show for the first time that the cytotoxicity against cultured T cells by several RTA mutants is directly proportional to the enzyme activity of RTA, suggesting this is a reliable system to measure translocation effects. Large discrepancies between cytotoxicity and enzyme action for a given pair of toxins are therefore attributable to differences in cell binding, uptake, or membrane translocation. Fluid phase uptake and cytotoxicity of isolated RTA are essentially identical to that of the single chain toxin PAP. This important finding suggests that RTA, and the A chain of class 2 RIPs in general, has not evolved special translocation signals to complement the increased target cell binding facilitated by RTB. Experiments with the lectin RCA and with ebulin suggest those toxins have diminished cytotoxicity probably mediated by comparative deficiencies in B chain binding. Addition of a KDEL sequence to RTA increases fluid phase uptake, consistent with the notion that transport to the ER is important for cytotoxicity. Fusion of MBP or GST to the amino terminus of RTA has little effect on enzyme action or cytotoxicity. This result is not altered by protease inhibitors, suggesting the fusion proteins are probably not cleaved prior to translocation of the toxic A chain and implying that the toxins can carry large passenger proteins into the cytoplasm, an observation with interesting potential for analytical and therapeutic chemistry.     

Seizure outcome after epilepsy surgery in children and adolescents

Development of efficient imaging techniques to trace neuronal connections would be very useful. Manganese ion (Mn2+) is an excellent T1 contrast agent for magnetic resonance imaging (MRI). Four reports utilizing radioactive Mn2+ in fish and rat brain indicate that Mn2+ may be useful for tracing neuronal connections. Therefore, the purpose of this work was to determine if Mn2+ can be used as an in vivo MRI neuronal tract tracer. The results indicate that topical administration of MnCI2 solution to the naris of mice as well as to the retinal ganglion cells via intravitreal injection leads to enhancement of contrast along the respective pathways. Therefore, application of Mn2+ to neurons allows the use of MRI to visualize neuronal connections.     

Readability of self-report clinical outcome measures

Since plasma is generally employed for amino acid analysis, we compared amino acid levels in plasma with those in serum for healthy individuals and examined the influence of separation and storage conditions on the stability of the samples. Then, we determined the amino acid levels of frozen serum samples obtained from sarin poisoned patients. A. Comparison of Amino Acid Levels in Plasma and Those in Serum Blood was collected from 5 healthy individuals. Then, heparinated plasma and serum were separated by centrifugation immediately after blood collection. Serum was also separated by centrifugation after standing whole blood at room temperature for 1 hour. Frozen plasma and serum were store at -40 degrees C for 5 months. All were subjected to analysis in an amino acid analyzer. It was found that the cystine (Cys) and 3-methyl-histidine (3-M-His) levels in serum and plasma were affected when stored in a frozen state, that the aspartate (Asp) level was changed according to the method of collecting serum, and that the taurine (Tau) and ornithine (Orn) levels were affected by standing blood. B. Analysis of Blood Taken from Sarin Poisoned Patients Twelve sarin poisoned patients were selected as subjects, and serum cholinesterase (Ch-E) and serum albumin (Alb) levels were determined. Amino acid analysis was conducted using an amino acid analyzer. Serum samples which had been obtained from the 6 patients and frozen and stored at -40 degrees C from 5 months were used for amino acid analysis. As a result, the serum Ch-E level decreased and the Alb level tended to rise. Since the Ch-E/Alb ratio was reduced in the sarin poisoned patients, it is considered useful for discrimination from liver cirrhosis in which both Ch-E and Alb levels decreased. Amino acid levels in the serum obtained from the sarin poisoned patients were compared with those of healthy individuals, both of which had been stored under the same conditions. There were significant differences in Asp, glutamate (Glu), phenylalanine (Phe), 3-M-His, glutamine (Gln), and Cys levels. The Glu, Phe, and Gln levels were not affected by storage of serum in a frozen state, while the Glu and Phe levels were elevated and the Gln level was reduced. Although Cys exhibited lower values in frozen serum samples, the Cys level was elevated with a rise in the serum Ch-E levels. Therefore, we deduced that Cys metabolism disorders also occur in sarin poisoning. As stated above, the Glu and Phe levels were elevated and the Gln and Cys levels were reduced, suggesting the presence of abnormal amino acid metabolism, in patients with sarin-poisoning.     

Lack of association between outcome measures of nerve regeneration

Studies of nerve regeneration in rodents utilize at least one of three classes of outcome measures: electrophysiology, morphometry, and functional tests. The assumption that these measures are correlated was tested utilizing a data set of 16 variables. Significant correlations (Spearman's rho, P < or = 0.05) were found within variable classes; however, none were found between classes. The three commonly utilized outcome measures do not measure the same phenomenon but rather discrete aspects of nerve regeneration.     

Reliability of clinical balance outcome measures in the elderly

BACKGROUND AND PURPOSE: Simple, practical and reliable clinical balance outcome measures are needed to assess baseline status and response to treatment in older people. The reliability of the clinical measures used in this testing protocol had not been determined for this population. This study assessed the inter-rater reliability of three commonly used clinical measures of balance: one leg standing, tandem gait and functional reach. METHOD: Two samples of older people were used: (1) non-disabled and (2) disabled community dwellers. All testing was performed in a single session by two trained examiners according to a standardized protocol. Intra-class correlations were calculated comparing the means of each clinical balance test for Examiner 1 with Examiner 2. RESULTS: Reliability coefficients were 0.75 for one leg standing, 0.73 for functional reach, and 0.31 for tandem gait for the non-disabled sample. Reliability coefficients were 0.85 for one leg standing, 0.79 for functional reach, and 0.62 for tandem gait for the disabled sample. CONCLUSIONS: These findings for the one leg standing and functional reach testing protocols in disabled and non-disabled older people can be used as outcome measures. Further study should be directed towards improving the reliability of the tandem gait test for use with older people.     

Minimise outcome measures after knee replacement

In a previous study the "performance variability" of 15 different assessment systems after knee replacement was analysed. The notion that different knee evaluation systems measure different underlying factors was suggested. Three systems that seemed to have different underlying factors were selected, and a factor analysis was carried out to reduce the number of items in each group. The number of items could be reduced by 70%-82% with a minor loss of discriminating capacity. All instruments could be separated into items of pain, strength, mobility or stability. Pain measured on a visual analogue scale and self-selected walking speed were recommended for longitudinal monitoring of the treatment effect after knee replacement.     

Brain blood flow alterations induced by therapeutic vagus nerve stimulation in partial epilepsy: I. Acute effects at high and low levels of stimulation

PURPOSE: Left cervical vagus nerve stimulation (VNS) decreases complex partial seizures (CPS) by unknown mechanisms of action. We hypothesized that therapeutic VNS alters synaptic activities at vagal afferent terminations and in sites that receive polysynaptic projections from these medullary nuclei. METHODS: Ten patients with partial epilepsy underwent positron emission tomographic (PET) measurements of cerebral blood flow (BF) three times before and three times during VNS. Parameters for VNS were at high levels for 5 patients and at low levels for 5. Resting BF measurements were subtracted from measurements during VNS in each subject. Subtraction data were averaged in each of 2 groups of 5 patients. t Tests were applied to BF changes in brain regions that receive vagal afferents and projections (significant at p < 0.05, corrected for repeated measures). RESULTS: In both the low- and high-stimulation groups during VNS, brain BF was (a) increased in the rostral, dorsal-central medulla; (b) increased in the right postcentral gyrus, (c) increased bilaterally in the hypothalami, thalami, and insular cortices, and in cerebellar hemispheres inferiorly; and (d) decreased bilaterally in hippocampus, amygdala, and posterior cingulate gyri. The high-stimulation group had greater volumes of activation and deactivation sites. CONCLUSIONS: Our findings suggest that left cervical VNS acutely increases synaptic activity in structures directly innervated by central vagal structures and areas that process left-sided somatosensory information, but VNS also acutely alters synaptic activity in multiple limbic system structures bilaterally. These findings may reflect sites of therapeutic actions of VNS.     

Action potential fatigue in nonmyelinated nerve fibers: garfish olfactory and rabbit vagus nerve

With the new method the fecal flora of 13 clinically healthy dogs aged 3 to 42 months was analysed qualitatively and quantitatively. It was characterized by that bacteroidaceae constituted the most prodominant flora, catenabacteria, streptococci, peptostreptococci, lactobacilli and bifidobacteria were the next most numerous, enterobacteria consisted the accompanying flora. The numbers of Clostridium perfringens were remarkably fluctuated and seem to be influenced by the composition of the food ingested by the host. The total cultivable counts averaged log 10.8 +/- 0.2/g. The composition of the Lactobacillus flora and Bifidobacterium flora in the feces of 34 dogs from 3 different age groups was analysed. In the feces of all age groups L. acidophilus, L. salivarius and L. fermenti with 9 different types were found. Within the lactobacilli L. acidophilus type VI c, L. salivarius type VI a and L. fermenti type IV b were most frequently found. L. acidophilus types VI c and XI, L. salivarius types VI a and VI b could not be placed in any established types of each species, and were described as new types. Bifidobacteria were regularly found in large numbers in the feces of dogs aged 2 to 24 months. B. adolescentis and B. pseudolongum consisted the main Bifidobacterium flora.     

Management of vagus nerve injury afer carotid endarterectomy

BACKGROUND: Inadvertent injury to the vagus nerve or its branches during carotid endarterectomy can result in adductor vocal cord paralysis (hoarseness) and cricopharyngeal dysfunction (dysphagia) with aspiration, known as "double trouble." This study describes our experience in the management of this complication in cases where conservative treatment failed. METHODS: All patients were examined by a vascular surgeon, a head and neck surgeon, and a speech therapist. Their examinations included comprehensive speech evaluation, video stroboscopy, video fluoroscopy, and methylene blue testing for aspiration. All patients underwent Teflon injections to medialize the paralyzed vocal cord and a cricopharyngeal myotomy to restore swallowing and alleviate aspiration. RESULTS: Fourteen patients, eight men and six women, were treated. The duration of dysfunction was 24 weeks in two patients, 6 weeks in four patients, 4 weeks in three patients, and 1 week in five patients. Five patients had severe dysfunction (defined as difficulty in swallowing both solid and liquid foods with more than 20% aspiration), seven patients had moderate dysfunction (defined as difficulty swallowing solid food with aspiration of less than 20%), and two patients had mild dysfunction (defined as difficulty in swallowing solids but with no aspirations). After the Teflon injections and myotomy, 13 of 14 patients had satisfactory outcomes, including normal voice and swallowing. CONCLUSIONS: Vagus nerve injury from a carotid endarterectomy can be a debilitating complication. Prevention, early recognition, and prompt correction of these injuries are important in the management of this complication.     

Latero-cervical tumors: apropos of a case of paraganglioma of the vagus nerve]

Borna disease virus (BDV) is a neurotropic, as yet unclassified, non-segmented, negative-sense, single-strand RNA virus. Natural infection with this virus has been reported to occur in horses and sheep. In addition, antibodies to BDV in plasma or BDV RNA in peripheral blood mononuclear cells (PBMCs) were also found in patients with neuropsychiatric diseases. We describe here the possible link between the patients with chronic fatigue syndrome (CFS) and infection with BDV.     

An application of transcutaneous electrical nerve stimulation to control pain in the elderly

A ten-year-old girl was referred for the management of a recurrent lobulated mass present in the upper anterior region. Histopathological investigations were suggestive of capillary hemangioma. Surgical excision of the lesion was performed and postoperative recovery was uneventful.     

The effect of the duration of GnRH-agonist down regulation before ovarian stimulation on the biological and clinical outcome after intracytoplasmic sperm injection

The effects of the alkaloids ajmaline, lupanine, sparteine, serpentine, strychnine, and yohimbine were studied with the loose patch clamp technique on sodium currents of isolated single skeletal muscle fibers. The IC50 values for half-maximal blocking of the sodium currents were 6.6 microM for ajmaline, 55.7 microM for quinidine, 168.8 microM for sparteine, and 1.2 mM for lupanine. The observed Na+ channel inhibition is in accordance with the use of ajmaline, quinidine and sparteine as antiarrhythmic drugs. The interference of alkaloids with Na+ channels can also be interpreted as a means to strongly interfere with neuronal transmission in herbivores. Alkaloids thus serve as chemical defense compounds for the plants producing them.     

Intraoperative facial nerve monitoring (IFNM) predicts facial nerve outcome after resection of vestibular schwannoma

Intraoperative facial nerve monitoring (IFNM) is a suitable technique for intraoperative facial nerve identification and dissection, especially in large vestibular schwannomas (VS) (acoustic neuroma). To evaluate its feasibility for estimating functional nerve outcome after VS resection 60 patients underwent surgery using IFNM. Out of this group the last 40 patients were included in a prospective study evaluating the prognostic value of various IFNM parameters (proximal and distal absolute EMG amplitude, stimulation threshold, and proximal-to-distal amplitude ratio) for prediction of initial postoperative facial nerve function and recovery of function. Stimulation threshold and absolute EMG amplitude proximally at the brain stem were both predictive for postoperative nerve function. Good initial facial nerve outcome (modified House Brackmann grading, mHB degree I and degree II) was found in 15/16 patients with a proximal EMG amplitude greater than 800 microV and in 19/22 patients with proximal stimulation threshold less than 0.3 mA. Sixteen of 16 patients with proximal stimulation threshold equal to or greater than 0.3 mA had moderate-to-severe facial palsy (mHB degree III or worse). Six of six patients without evokable proximal amplitude initially had insufficient nerve function (mHB degree IV). Intraoperative decrease of the proximal amplitude was associated with an unfavourable outcome, whereas distal amplitudes usually stayed unchanged. Mean distal EMG amplitudes were also found to be decreased with poor nerve function, which may mean that the tumour had already affected the nerve. A proximal amplitude of 300 microV or less and a proximal-to-distal amplitude ratio below 1:3 were found in the absence of functional recovery in 6/8 (75%) and 5/6 (83%) patients with initial mHB degree IV, respectively. Two patients with initial mHB degree IV improved to mHB degree III despite intraoperative evidence of missing functional nerve integrity. Therefore, functional recovery cannot be predicted by IFNM in all cases of anatomical nerve preservation. We conclude that a minimum follow-up period of 1 year may still be advisable even in certain patients without evidence of intraoperative functional nerve integrity.     

Effect of malnutrition after acute stroke on clinical outcome

BACKGROUND AND PURPOSE: Malnutrition has received little attention in acute stroke, although it represents a risk of decreased immunity and nosocomial infections. Our objectives were to determine the prevalence of malnutrition after 1 week of hospitalization in acute stroke and to establish its relation to the stress response and neurological outcome. METHODS: The study included 104 patients with an acute stroke of less than 24 hours' duration. Nutritional parameters (triceps skinfold thickness, midarm muscle circumference, serum albumin, and calorimetry) were evaluated at admission and after 1 week. Stress response (free urinary cortisol) was measured daily during the first week. Neurological deficit was evaluated by the Canadian Stroke Scale. Clinical outcome was estimated by the Barthel Index 1 month after the acute stroke. Patients received an oral standard diet or polymeric enteral nutrition when they had swallowing difficulties. RESULTS: Protein-energy malnutrition was observed in 16.3% of patients at inclusion and in 26.4% after the first week, with a significant decrease in fat (P = .002) and visceral protein compartments (P = .049). Malnourished patients showed higher stress reaction and increased frequency of infections and bedsores in comparison with the appropriately nourished group. Multiple logistic regression analysis showed that malnutrition after 1 week (odds ratio, 3.5; 95% confidence interval, 1.2 to 10.2) and elevated free urinary cortisol (odds ratio, 3.3; confidence interval, 1.05 to 10.2) increased the risk of poor outcome (death or Barthel Index < or = 50 on the 30th day of follow-up) independently of age and nutritional status at admission. CONCLUSIONS: Our findings suggest that protein-energy malnutrition after acute stroke is a risk factor for poor outcome. Early appropriate enteral caloric feeding did not prevent malnutrition during the first week of hospitalization.     

Somatosensory trigeminal evoked potentials after gingival stimulation of the mental nerve. Normal values

OBJECTIVE: Somatosensory evoked potentials were recorded following unilateral stimulation of the mental nerve in the gum of 100 healthy volunteers aged between 17 and 22 years. METHODS AND RESULTS: Responses were recorded until 100 ms with electrodes placed over the scalp (C5/C6) referenced to central frontal (Fz). In 10 subjects, simultaneous recordings were made in masticatory and facial muscles to detect possible muscle artefacts. Stimulation was effected using a specially-designed stimulator adaptable to each individual. Contralateral responses consisted of four very constant deflexions (N12, P19, N26 and P35) forming a W-shaped complex of mean duration 31.27 ms. Tables of normality were compiled for latencies and amplitudes with confidence intervals of 99.8% reliability. Constancy of deflexions, stability of response (by serial studies), and possible sexual differences were also studied. Muscle artefacts were ruled out, and the participation of the mental nerve in the genesis of the responses was confirmed. CONCLUSION: We consider the proposed method a reliable alternative to other procedures used to obtain TEPs.     

Tuberculosis: infection control measures

A 58-year-old man with acute mitral and aortic endocarditis suffered an acute ascending aortic dissection. The patient had a double valve replacement, combined with replacement of the ascending aorta with a Dacron graft and sealing and closure of the proximal and distal aortic segments with surgical glue. Six months after the operation the patient is doing well with normal function of both valve prostheses and aortic vascular graft.