iMAX: A new tool for assessment of motor axon excitability. A multicenter prospective study.

OBJECTIVE: This study was undertaken to establish by a multicentric approach the reliability of a new technique evaluating motor axon excitability. METHODS: The minimal threshold, the lowest stimulus intensity allowing a maximal response by 1 mA increments (iUP) and then by 0.1 mA adjustments (iMAX) were prospectively derived from three nerves (median, ulnar, fibular) in four university centers (Liège, Marseille, Fraiture, Nice). iMAX procedure was applied in 28 healthy volunteers (twice) and 32 patients with Charcot-Marie-Tooth (CMT1a), chronic inflammatory demyelinating polyneuropathy (CIDP), Guillain-Barré syndrome (SGB) or axonal neuropathy. RESULTS: Healthy volunteers results were not significantly different between centers. Correlation coefficients between test and retest were moderate (> 0.5). Upper limits of normal were established using the 95th percentile. Comparison of volunteers and patient groups indicated significant increases in iMAX parameters especially for the CMT1a and CIDP groups. In CMT1a, iMAX abnormalities were homogeneous at the three stimulation sites, which was not the case for CIDP. CONCLUSIONS: The iMAX procedure is reliable and allows the monitoring of motor axon excitability disorders. SIGNIFICANCE: The iMAX technique should prove useful to monitor motor axonal excitability in routine clinical practice as it is a fast, non-invasive procedure, easily applicable without specific software or devices.

Influence of limb position on assessment of nerve mechanical properties by using shear wave ultrasound elastography.

INTRODUCTION: Evaluation of nerve mechanical properties has the potential to improve assessment of nerve impairment. Shear wave velocity, as measured by using shear wave (SW) ultrasound elastography, is a promising indicator of nerve mechanical properties such as stiffness. However, elucidation of external factors that influence SW velocity, particularly nerve tension, is required for accurate interpretations. METHODS: Median and ulnar nerve SW velocities were measured at proximal and distal locations with limb positions that indirectly altered nerve tension. RESULTS: Shear wave velocity was greater at proximal and distal locations for limb positions that induced greater tension in the median (mean increase proximal 89.3%, distal 64%) and ulnar (mean increase proximal 91.1%, distal 37.4%) nerves. DISCUSSION: Due to the influence of nerve tension when SW ultrasound elastography is used, careful consideration must be given to limb positioning.

Relations between sensory symptoms, touch sensation, and sensory neurography in the assessment of the ulnar neuropathy at the elbow.

OBJECTIVES: To evaluate sensitivity, specificity and predictive values of sensory findings in ulnar neuropathy at the elbow (UNE), differences according to UNE localization and pathophysiology, and relation between the sites of sensory symptoms, abnormal evaluation of sensation and neurographic findings of ulnar sensory nerve. METHODS: Hand diagram and Semmes-Weinstein monofilaments were used for clinical evaluation in four ulnar hand territories. Sensory neurography was measured in the fourth and fifth digits-wrist segments (U5) and in the dorsal ulnar cutaneous nerve. RESULTS: We enrolled 75 idiopathic UNE cases and 180 controls. Symptoms in the fifth digit, reduction of touch sensation and U5 sensory nerve action potential amplitude (SNAPa) had the highest sensitivity, specificity and predictivity in UNE diagnosis. The normal/abnormal sensory clinical findings of the fifth digit matched with normal/abnormal U5 SNAP more than the matching of sensory parameters in the other ulnar hand sites. Sensory anomalies were more frequent in predominantly axonal than demyelinating UNE. There were no differences according to UNE location. CONCLUSION: Sensory anomalies of the fifth digit are constant findings in UNE more than anomalies of the other ulnar nerve hand regions. SIGNIFICANCE: Probably the fascicles from fifth digit are the most liable to damage at elbow.

The Ulnar Nerve at Elbow Extension and Flexion: Assessment of Position and Signal Intensity on MR Images.

Purpose To assess the position and signal intensity of the ulnar nerve at elbow extension and flexion by using magnetic resonance imaging. Materials and Methods Institutional review board approval and written informed consent were obtained. Transverse T2-weighted images were obtained perpendicular to the upper arm in 100 healthy elbows of 50 volunteers (23 men, 27 women; age range, 21-57 years) and nine elbows with ulnar neuropathy (five men, four women; age range, 24-59 years) with extension and 130° of flexion. Ulnar nerve position was classified into three types: no dislocation, subluxation, or dislocation. One-way analysis of variance, paired t tests, Student t tests, and multiple regression analysis were used to analyze correlations between ulnar nerve movement angle during flexion and age, sex, presence of the anconeus epitrochlearis muscle, and ulnar neuropathy and to compare the contrast-to-noise ratio of nerve to muscle between extension and flexion. Results Nerve positions in healthy elbows were as follows: All had no dislocation at extension, and at flexion, 51 of 100 elbows (51.0%) had no dislocation, 30 of 100 elbows (30.0%) had subluxation, and 19 of 100 elbows (19.0%) had dislocation. Nerve movement angle was smaller in elbows with the anconeus epitrochlearis muscle than in those without the muscle (P = .045, .015). Presence of the muscle was the only significant factor associated with nerve movement angle (P = .047, .013). Only dominant elbows with nerve movement angle of less than 15° and nondominant elbows with nerve movement angle of less than 10° showed contrast-to-noise ratio increase at flexion (P = .021-.030). Conclusion Ulnar nerve movement during flexion was apparent in approximately half of healthy elbows and was similar between healthy elbows and elbows with ulnar neuropathy. Nerve signal intensity increased during flexion only in elbows without apparent nerve movement. (©) RSNA, 2016 Online supplemental material is available for this article.

F Wave Study in Amyotrophic Lateral Sclerosis: Assessment of Segmental Motoneuronal Dysfunction.

BACKGROUND: Dysfunctional spinal circuit may play a role in the pathophysiology of amyotrophic lateral sclerosis (ALS). The purpose of this study was to use F waves for assessment of segmental motoneuronal excitability following upper motor neuron (UMN) dysfunctions in ALS. METHODS: We studied the F waves of 152 ulnar nerves recorded from abductor digiti minimi in 82 patients with ALS. Two groups of hands were defined based on the presence or absence of pyramidal signs in the same upper limb. The group with pyramidal signs in the upper limbs was designated as the P group, and the group without pyramidal signs in the upper limbs was designated as the NP group. RESULTS: The mean (P < 0.001), median (P < 0.001) and maximum (P = 0.035) F wave amplitudes, mean (P < 0.001), median (P < 0.001) and maximum (P = 0.003) F/M amplitude ratio, index repeating neuron (P < 0.001) and index repeater F waves (P < 0.001) of the P group were significantly increased compared with the NP group. No significant differences were identified for F wave chronodispersion (P = 0.628), mean F wave latency (P = 0.151), minimum F wave latency (P = 0.211), maximum F wave latency (P = 0.199), F wave persistence (P = 0.738), F wave duration (P = 0.152), F wave conduction velocity (P = 0.813) and number of giant F waves (P = 0.072) between the two groups. CONCLUSIONS: In this study, increased F wave amplitude, F/M amplitude ratio and number of repeater F waves reflected enhanced segmental motoneuronal excitability following UMN dysfunctions in ALS.

The normal sensibility of the hand declines with age--a proclamation for the use of delta two-point discrimination values for sensibility assessment after nerve reconstruction.

The scores used to evaluate sensibility after digital nerve reconstruction do not take the patient's age into consideration, although there is evidence that the outcome after digital nerve reconstruction is age-dependent. However, it is not clear if the normal sensibility of the hand is also age-dependent, as the existing studies have major limitations. We evaluated the normal sensibility of the hand in 232 patients using static and moving two-point discrimination (2PD) tests and the Semmes-Weinstein-monofilament test. We found the climax of sensibility in the third decade with age-dependent deterioration afterwards in all three tests. Mean 2PD values of the radial digital nerve of the index finger (N3) showed to be significantly lower than values of the ulnar digital nerve of the small finger (N10). To overcome shortcomings of classification systems that do not consider the patient's age and inter-individual differences, we suggest using the difference of the static 2PD values of the injured to the uninjured contralateral nerve (delta 2PD) for assessment of sensibility after digital nerve reconstruction.

Factors that influence the selection of sterile glove brand: a randomized controlled trial evaluating the performance and cost of gloves.

PURPOSE: To determine whether glove use modifies tactile and psychomotor performance of health care providers when compared with no glove use and to evaluate factors that influence the selection of sterile glove brand. METHODS: Forty-two anesthesia providers (nine anesthesiologists, seven nurse anesthetists, 20 residents, six student nurse anesthetists) enrolled in and completed this cross-over randomized trial from May 2010 until August 2011. Participants underwent standardized psychomotor testing while wearing five different types of protective gloves. Assessments of psychomotor performance included tactile, fine motor/dexterity, and hand-eye coordination tests. Subjective ratings of glove comfort and performance were reported at the completion of each glove trial. The manufacturer's suggested retail price was collected for each glove tested. RESULTS: There were statistically significant differences in touch sensitivity for all nerve distributions, with all glove types resulting in less sensitivity than a bare hand. When compared with the non-sterile glove, only the thickest glove tested (Ansell Perry Orthopaedic) was found to have less touch sensitivity. Fine motor dexterity testing revealed no statistically significant differences in time to completion amongst glove types or bare handed performance. In hand-eye coordination testing across treatment conditions, the thickest glove tested (Ansell Perry(®) Orthopaedic) was the only glove to show a statistically significant difference from a bare hand. There were statistically significant differences in glove comfort ratings across glove types, with latex-free, powder-free (Cardinal Esteem(®)), and latex powder-free (Mölnlycke-Biogel(®)) rated highest; however, there were no statistically significant differences in subjective performance ratings across glove types. CONCLUSIONS: Given the observed similarities in touch sensitivity and psychomotor performance associated with five different glove types, our results suggest that subjective provider preferences, such as glove comfort, should be balanced against material costs.

[Assessment of the effects of surgical treatment options for cubital tunnel syndrome on the ulnar nerve by USG and EMG]. / Kübital tünel sendromunda cerrahi tedavi seçeneklerinin ulnar sinir üzerine etkilerinin USG ve EMG ile degerlendirilmesi.

OBJECTIVES: The morphology and functional results of the ulnar nerve were evaluated in patients treated with simple decompression and anterior subcutaneous transposition due to the diagnosis of cubital tunnel syndrome. PATIENTS AND METHODS: Thirteen elbows of 13 patients (8 males, 5 females; mean age 41 years; range 25 to 56 years) treated with simple decompression and anterior subcutaneous transposition due to the diagnosis of cubital tunnel syndrome were investigated. The involvement was on the dominant side in six patients. There was a 25° cubitus valgus deformity in one patient. No significant etiologic cause was found in the other patients. Seven patients were treated with anterior subcutaneous transposition and six with simple decompression. During the follow-ups, the atrophy magnitude, the new pressure areas and the intrinsic structure of the nerve tissue along the ulnar nerve path were evaluated by using soft tissue ultrasonography (USG). The flow rate of the artery supplying the ulnar nerve by Doppler mode USG and ulnar nerve conduction rate by electromyography (EMG) were assessed. Functional results were evaluated according to the Akahori's criteria and the modified Bishop scoring system. The average follow-up time was two years (range 12-44 months). RESULTS: In the Doppler USG examination, no arterial blood flow supplying the ulnar nerve was found in five of seven patients who underwent anterior transposition. A blood flow decrease of approximately 20 cm/s was found in two patients. A blood flow decrease of 10 cm/s on average was found in six patients who underwent simple decompression. There was a significant difference between the two groups (p<0.05). The control EMG revealed an increase of 9 m/s in the ulnar nerve conduction rate in the transposition group (p>0.05) and an increase of 17 m/s in the simple decompression group compared to the preoperative values (p<0.05). In seven patients who underwent anterior subcutaneous transposition, five excellent and two good results and an average of 8.2 points were achieved according to the Akahori's criteria and the modified Bishop scoring system, respectively. In six patients who underwent simple decompression, five excellent results, and one good result and an average of 8.1 points were achieved according to the Akahori's criteria and the modified Bishop scoring system, respectively. There was no statistically significant difference between functional results of both surgical techniques (p>0.05). CONCLUSION: Although the functional results of the cubital tunnel syndrome surgery are good, it must be noted that the blood supply to the nerve may be distorted, especially during anterior transposition. If there is no additional requirement, simple decompression may be considered as the first option.

The assessment of the ulnar nerve at the elbow by ultrasonography in children.

We evaluated the morphological changes to the ulnar nerve of both elbows in the cubital tunnel by sonography in a total of 237 children, of whom 117 were aged between six and seven years, 66 between eight and nine years, and 54 between ten and 11 years. We first scanned longitudinally in the extended elbow and then transversely at the medial epicondyle with the elbow extended to 0 degrees . We repeated the scans with the elbow flexed at 45 degrees , 90 degrees , and 120 degrees . There were no significant differences in the area of the ulnar nerve, but the diameter increased as the elbow moved from extension to flexion in all groups. More importantly, the ulnar nerve was subluxated anteriorly on to the medial epicondyle by 1.5% to 1.9% in extended elbows, by 5.9% to 7.9% in those flexed to 45 degrees , by 40.0% to 44% in those flexed to 90 degrees , and by 57.4% to 58.1% in those flexed to 120 degrees , depending on the age group. Sonography clearly and accurately showed the ulnar nerve and was useful for localising the nerve before placing a medial pin. Because the ulnar nerve may translate anteriorly onto the medial epicondyle when the elbow is flexed to 90 degrees or more, it should never be overlooked during percutaneous medial pinning.

Stimulus-response curve of human motor nerves: multicenter assessment of various indexes.

The value of various indexes to characterize the stimulus-response curve of human motor nerves was assessed in 40 healthy subjects recruited from four European centers of investigation (Créteil, Lausanne, Liège, Marseille). Stimulus-response curves were established by stimulating the right median and ulnar motor nerves at the wrist, with stimulus durations of 0.05 and 0.5 ms. The following parameters were studied: the threshold intensity of stimulation to obtain 10% (I 10), 50% (I 50), and 90% (I 90) of the maximal compound muscle action potential, the ratios I 10/I 50, I 90/I 50, (I 90 - I 10)/I 10, (I 90-I 50)/I 50, and (I 50 - I 10)/I 10, and the slopes of the stimulus-response curves with or without normalization to I 50. For each parameter, within-center variability and reproducibility (in a test-retest study) were assessed and between-center comparisons were made. For most of the parameters, the results varied significantly within and between the centers. Within the centers, only the ratios I 10/I 50 and I 90/I 50 were found constant and reproducible. Between the centers, the absolute intensity thresholds (I 10, I 50, I 90) and the ratio I 90/I 50 did not show significant differences at stimulus duration of 0.5 ms, whatever the stimulated nerve. The reduced variability and good reproducibility of the ratios I 10/I 50 and I 90/I 50 open perspectives in neurophysiological practice for the use of these indexes of the stimulus-response curve, a rapid and noninvasive test.

Assessment of sensorimotor cortical representation asymmetries and motor skills in violin players.

As a model for use-dependent plasticity, the brains of professional musicians have been extensively studied to examine structural and functional adaptation to unique requirements of skilled performance. Here we provide a combination of data on motor performance and hand representation in the primary motor and somatosensory cortex of professional violin players, with the aim of assessing possible behavioural consequences of sensorimotor cortical asymmetries. We studied 15 healthy right-handed professional violin players and 35 healthy nonmusician controls. Motor and somatosensory cortex asymmetry was assessed by recording the motor output map after transcranial magnetic stimulation from a small hand muscle, and by dipole source localization of somatosensory evoked potentials after electrical stimulation of the median and ulnar nerves. Motor performance was examined using a series of standardized motor tasks covering different aspects of hand function. Violin players showed a significant right-larger-than-left asymmetry of the motor and somatosensory cortex, whereas nonmusician controls showed no significant interhemispheric difference. The amount of asymmetry in the motor and somatosensory cortices of musicians was significantly correlated. At the behavioural level, motor performance did not significantly differ between musicians and nonmusicians. The results support a use-dependent enlargement of the left hand representation in the sensorimotor cortex of violin players. However, these cortical asymmetries were not paralleled by accompanying altered asymmetries at a behavioural level, suggesting that the reorganisation might be task-specific and does not lead to improved motor abilities in general.

End-to-side nerve coaptation: a qualitative and quantitative assessment in the primate.

There are several reasons why end-to-side nerve coaptation has not been widely adopted clinically. Among these are the putative damage inflicted on the donor nerve and the variable quality of the regeneration in the recipient nerve. So far experiments on end-to-side nerve repair have been short term and mostly carried out on rats. This long-term study of end-to-side nerve repair of ulnar to median and median to ulnar nerve was performed using adult nonhuman primates. Eleven nerve repairs were studied at different time points. Eighteen, 22, 33 and 57 months after surgery a qualitative and quantitative analysis of the donor nerve and regenerating nerve revealed variable levels of percentage axonal regeneration compared with matched controls (1.4%-136%). Morphological evidence of donor nerve damage was identified distal to the coaptation site in four of the 11 cases, and in these cases the best axonal regeneration in the corresponding recipient nerves was observed. This donor nerve damage could neither be demonstrated in terms of a decrease in axon counts distal to the coaptation nor as donor target organ denervation. Recipient target organ regeneration like the axonal regeneration varied, with evidence of motor regeneration in eight out of 11 cases and sensory regeneration, as measured by percentage innervation density compared with matched controls, varied from 12.5% to 49%. Results from the present study demonstrate that the end-to-side coaptation technique in the nonhuman primate does not give predictable results. In general the motor recovery appeared better than the sensory and in those cases where donor nerve damage was observed there was better motor and sensory regeneration overall than in the remaining cases.

F wave study in amyotrophic lateral sclerosis: assessment of balance between upper and lower motor neuron involvement.

OBJECTIVE: We sought to record significant F wave variable changes in ALS patients having no advanced disease. Furthermore, an interpretation of these F wave abnormalities in the context of upper (UMN) and lower motor neuron (LMN) dysfunction was attempted. METHODS: Standard motor and sensory conduction study was performed to the ulnar nerves of 23 patients with ALS (13 males and 10 females with mean age 67.2+/-5.3 years), having a clinically predominant LMN syndrome. A series of 40 electrical stimuli were also delivered to both their ulnar nerves in order to obtain F waves. The following F wave variables were estimated: F persistence, F wave latency, amplitude, duration and F chronodispersion. Twenty-three, age-and gender-matched healthy volunteers served as controls. RESULTS: Both the distal and proximal ulnar a-CMAPs (P=0.001) and the MCV (P=0.014) values were significantly decreased in patients, than the controls. The sensory conduction study was normal. The ulnar F wave persistence in the ALS patients was significantly lower than that of the controls (P=0.0007). The mean (P=0.0001), minimal (P=0.0001) and maximal (P=0.0001) F wave latencies were significantly prolonged, the F wave amplitudes (P=0.0001) were significantly higher and the F wave chronodispersion (P=0.014) was significantly increased in the patients than the controls. CONCLUSIONS: Significant F wave abnormalities occur in patients with ALS, even those patients having no advanced disease. Increased F wave amplitudes combined with low persistence is a pattern consistent with ALS. SIGNIFICANCE: Our results show that patients with ALS having predominantly LMN involvement also have electrophysiological UMN dysfunction.

Inter-observer reliability in assessment of sensation of skin lesion and enlargement of peripheral nerves in leprosy patients.

The accurate diagnosis of leprosy is important to both individuals and to the community. The diagnosis of leprosy is based on clinical examination. However, the reliability of clinical assessment of sensation in skin lesions and thickness of peripheral nerves on palpation has not been well studied, due to the lack of a gold standard. We report an inter-tester reliability study of the clinical assessment of skin lesions and thickness of ulnar and popliteal nerves in leprosy patients by different staff. For sensory testing of skin lesions, the agreement between the leprologist and leprosy control staff, and between one student and leprosy control staff, was poor (kappa values < 0-4). The agreement between the leprologist and the two students, between the two students, and between the other student and local leprosy control staff were fair (kappa values > 0.4, but < 0-6). For the palpation of ulnar and popliteal nerves, the agreement ranged from 0.36 to 0.52 and from 0.02 to 0.29 in different pairs of testers, respectively. The reliability of clinical diagnostic skills based on both sensory testing of skin lesions with the cotton wool method and palpation of superficial peripheral nerves was unsatisfactory.

Diagnostic strategy for familial and sporadic cases of neuropathy associated with 17p11.2 deletion.

Clinical, electrophysiologic and molecular studies were performed on at-risk members of 14 families with hereditary neuropathy with liability to pressure palsies (HNPP), in order to detect asymptomatic carriers of the 17p11.2 deletion. Sporadic cases due to de novo deletion accounted for 21% of the investigated HNPP families. Approximately one half of deletion carriers were asymptomatic and did not display significant signs on clinical examination. The electrophysiologic hallmark in both symptomatic and asymptomatic deletion carriers was the presence of a nonuniform sensorimotor demyelinating polyneuropathy with conduction abnormalities preferentially located at common entrapment sites and distal nerve segments. A perfect correlation was found between the molecular and electrophysiologic analyses. A reliable screening method to detect clinically unaffected carriers of the deletion in families with HNPP was the evaluation of motor conduction in at least two nerves across usual entrapment sites, especially the ulnar nerve at the elbow, and evaluation of sensory conduction in the sural nerve. In sporadic cases due to a de novo deletion, electrophysiologic studies were suggestive but not sufficient for the diagnosis, and molecular analysis represented the most sensitive diagnostic tool.

Assessment of the postoperative residual curarisation using the train of four stimulation with acceleromyography.

The aim of this study was to measure the incidence of patients with train of four ratio < 0.9 in the immediate postoperative period using acceleromyography. At arrival in recovery room, 257 patients were enrolled. Train of four ratio was assessed at the adductor pollicis using TOF-GUARD INMT apparatus. Patients were divided in two groups according to TOF ratio < (group 1) or > (group 2) to 0.9. Demographic variables, dose (mg), dose/weight ratio (mg.kg-1) of atracurium and surgery duration (min) were registered. There was no difference in demographic variables, duration of surgery (100.90 +/- 67.38/94.83 +/- 62.42 min), number of incidence reversal of neuromuscular block. Patients in group 1 (n = 72) received a higher dose (54.58 +/- 38.03/41.43 +/- 19.47 mg) of atracurium compared to group 2 (n = 176). Thirty percent of patients presented a train of four ratio < 0.7 and 13% < 0.9. TOF-GUARD INMT was easy to use.

Assessment of sensory function in neonatal sheep with somatosensory evoked potentials: methodology and normative data.

Fetal sheep are increasingly used as animal models for fetal surgical interventions such as repair of myelomeningocele. Since behavioral observations cannot provide objective information about preservation of sensory function, we have developed a technique for reliably recording somatosensory evoked potentials in neonatal sheep. We determined anatomic criteria for placement of recording electrodes over the somatosensory cortex using external landmarks, and recorded normative data for both ulnar and posterior tibial nerve stimulation in a series of normal neonatal sheep. The methodology and normative data are presented in this report; a companion paper demonstrates the utilization of this technique in a variety of experimental fetal interventions.

[Neurophysiological assessment of children with obstetric brachial plexus palsy]. / Evalución neurofisiológica de los niños con parálisis del plexo braquial obstétrica.

INTRODUCTION: The objectives of the neurophysiological evaluation of infants with brachial plexus palsy are to determine the time of occurrence of the lesion, to locate the lesion and to determine its course. METHODS AND CONCLUSIONS: These objectives are achieved by studying affected upper extremity muscles by needle electromiography (EMG) and affected nerves by motor and sensory conduction studies. EMG is performed in the first week of life in those patients with brachial plexus palsy of unknown etiology to determine the age of the lesion for medico-legal reasons. EMG is performed before surgery for tendon transfer in the selected muscles to assure that they are normal. EMG and motor and sensory conduction studies are performed at the age of 3 and 6 months in infants with less than 4 muscle weakness to determine candidates for surgical exploration. Motor and sensory nerve conduction studies are performed intraoperative to determine the functional status of the affected axons and the best surgical procedure (neurotization, neurolysis and/or neuroma resection and homologous nerve graft).

Performance assessment of an adaptive model-based feedback controller: comparison between atracurium, mivacurium, rocuronium and vecuronium.

The performance of an adaptive model-based controller for the administration of atracurium, mivacurium, rocuronium and vecuronium was compared in 159 adult surgical patients. The degree of neuromuscular block was set to 90% for atracurium, rocuronium and vecuronium and to 95% for mivacurium. Performance was assessed by calculating the median prediction error (bias), median absolute performance error (inaccuracy), divergence, wobble, the mean offset and the mean standard deviation from the setpoint. All indices of controller performance showed minimal deviation of the actual neuromuscular block from the setpoint. Although the controller appeared to be able to control rocuronium induced block at 90% and mivacurium induced block at 95% better than atracurium and vecuronium block at 90%, the differences in the controller performance between the four studied relaxants were small and have hardly any clinical significance. We conclude that a model-based adaptive controller is useful in the administration of atracurium, mivacurium, rocuronium or vecuronium.

Assessment of neuromuscular block at the thumb and great toe using accelography in infants.

We assessed neuromuscular block at the thumb and great toe using accelography after the administration of vecuronium in infants. Train-of-four stimuli were simultaneously applied to the ulnar and tibial nerves using cutaneous electrodes. Anaesthesia was maintained with nitrous oxide (66%) in oxygen and sevoflurane (1%). Vecuronium 0.1 mg.kg-1 was used for paralysis and reversed with intravenous neostigmine 0.04 mg.kg-1 with atropine 0.02 mg.kg-1 when the train-of-four ratio on the right great toe returned to 25%. The mean (SD) times from initial administration of vecuronium to completion of maximal block on the thumb and great toe were 78 (21.1) s and 75 (14.3) s, respectively (p > 0.05). The times from maximal block to 25% recovery of twitch height at the thumb and great toe were 46 (9.1) min and 45 (9.0) min, respectively. The reversal time from 25% to 75% of the train-of-four ratio after the administration of neostigmine was 136 (49.1) s. We conclude that neuromuscular monitoring of the great toe in infants may be a suitable alternative when the thumb is inaccessible.