The addition of the MEP amplitude of finger extension muscles to clinical predictors of hand function after stroke: A prospective cohort study.

BACKGROUND: Within the first 72 hours after stroke, active finger extension is a strong predictor of long-term dexterity. Transcranial magnetic stimulation may add prognostic value to clinical assessment, which is especially relevant for patients unable to follow instructions. OBJECTIVE: The current prospective cohort study aims at determining whether amplitude of motor evoked potentials of the extensor digitorum communis (EDC) can improve clinical prediction after stroke when added to clinical tests. METHODS: the amplitude of motor evoked potentials of the affected EDC muscle at rest was measured in 18 participants within 4 weeks after stroke, as were the ability to perform finger extension and the Fugl-Meyer Motor Assessment of the upper extremity (FMA_UE). These three determinants were related to the FMA_UE at 26 weeks after stroke (FMA_UE26), both directly, and via the proportional recovery prediction model. The relation between amplitude of the motor evoked potentials and FMA_UE26 was evaluated for EDC. For comparison, also the MEP amplitudes of biceps brachii and adductor digiti minimi muscles were recorded. RESULTS: Patients' ability to voluntarily extend the fingers was strongly related to FMA_UE26, in our cohort there were no false negative results for this predictor. Our data revealed that the relation between amplitude of motor evoked potential of EDC and FMA_UE26 was significant, but moderate (rs = 0.58) without added clinical value. The other tested muscles did not correlate significantly to FMA_UE26. CONCLUSIONS: Our study demonstrates no additional value of motor evoked potential amplitude of the affected EDC muscle to the clinical test of finger extension, the latter being more strongly related to FMA_UE26.

A gait paradigm reveals different patterns of abnormal cerebellar motor learning in primary focal dystonias.

Accumulating evidence points to a role of the cerebellum in the pathophysiology of primary dystonia. The aim of this study was to investigate whether the abnormalities of cerebellar motor learning in primary dystonia are solely detectable in more pure forms of cerebellum-dependent associative motor learning paradigms, or whether these are also present in other motor learning paradigms that rely heavily on the cerebellum but in addition require a more widespread sensorimotor network. Twenty-six patients with various forms of focal dystonia and 10 age-matched healthy controls participated in a motor learning paradigm on a split-belt treadmill. By using reflective markers, three-dimensional kinematics were recorded using a 6-camera motion analysis system. Adaptation walking parameters were analyzed offline, comparing the different dystonia groups and healthy controls. Patients with blepharospasm and writer's cramp were significantly impaired on various adaptation walking parameters. Whereas results of cervical dystonia patients did not differ from healthy controls in terms of adaptation walking parameters, differences in parameters of normal gait were found. We have here demonstrated abnormal sensorimotor adaptation with the split-belt paradigm in patients with blepharospasm and writer's cramp. This reinforces the current concept of cerebellar dysfunction in primary dystonia, and that this extends beyond more pure forms of cerebellum-dependent associative motor learning paradigms. However, the finding of normal adaptation in cervical dystonia patients indicates that the pattern of cerebellar dysfunction may be slightly different for the various forms of primary focal dystonia, suggesting that actual cerebellar pathology may not be a primary driving force in dystonia.

The clinical utility of botulinum toxin injections targeted at the motor endplate zone in cervical dystonia.

BACKGROUND AND PURPOSE: Cervical dystonia (CD) patients usually receive repeated botulinum neurotoxin (BoNT) injections. The aims of this study were to evaluate the feasibility of motor endplate zone (MEZ) detection of relevant cervical muscles in CD patients receiving chronic BoNT treatment and to compare the treatment effect of half-dosed, endplate-targeted injections to standard BoNT injections. METHODS: In study 1, high-density surface electromyography (HD-sEMG) was recorded from the sternocleidomastoid (SCM) and splenius capitis (SC) muscles in 18 CD patients with ongoing BoNT treatment, by which the location of the MEZ was determined. In study 2, nine additional patients with rotational-type CD participated in a treatment effect study where they received either half of their regular BoNT dose through endplate-targeted injections or their normal BoNT dose through standard injections (crossover design). Dystonia severity was recorded before and 4 weeks after each treatment session (Toronto Western Spasmodic Torticollis Rating Scale severity subscore). RESULTS: In the SCM muscle the MEZ was located at the lower border of the superior third part of the muscle, and in the SC muscle at half muscle length. Endplate-targeted, half-dosed BoNT injection resulted in a similar treatment effect to injecting the full dose in the standard technique. CONCLUSIONS: Half-dosed, endplate-targeted BoNT injections lead to a similar treatment effect to the standard BoNT injection protocol. MEZ detection confronts the clinician with some technical challenges, such as the ability of accurate and technically optimal placement of the electrode grid and correct interpretation of the HD-sEMG signal.

Can forearm muscle activity be selectively recorded using conventional surface EMG-electrodes in transcranial magnetic stimulation? A feasibility study.

OBJECTIVES: This feasibility study evaluates the effect of varying the position of conventional surface EMG-electrodes on the forearm when using Transcranial Magnetic Stimulation (TMS). The aim was to find optimal bipolar electrode positions for forearm extensor muscles, which would be clinically relevant to predict motor recovery after stroke. METHODS: In a healthy female subject, three rings of surface EMG-electrodes were placed around the dominant forearm, leading to 200 different electrode pairs. Both peripheral electrical stimulation and TMS were applied at suprathreshold intensities. RESULTS: With electrical stimulation of the median and radial nerve, similar waveform morphology was found for all electrode pairs, covering both flexors and extensors. Also with TMS, remarkable similarities between all electrode pairs were found, suggesting minimal selectivity. In both peripheral electrical stimulation and TMS, the curves became more irregular with decreasing inter-electrode distances. CONCLUSION: Neither with peripheral electrical stimulation nor with TMS it was possible to selectively record extensor or flexor forearm muscle activity using conventional surface EMG-electrodes. SIGNIFICANCE: Despite this negative result, the important role of the forearm extensor muscles in the prognosis of motor recovery after stroke warrants further research into novel methods for selectively recording muscle activity in TMS other than by conventional surface EMG.

Early infantile electroencephalography in patients with spina bifida*.

OBJECTIVE: The aim of this prospective study was to assess the prognostic value of electroencephalography in infants born with spina bifida.31 infants with spina bifida born between 2002 and 2007 at the Radboud Nijmegen University Medical Centre were evaluated and followed for 2½ years. Electroencephalography (EEG) was performed during the first 8 weeks after birth. RESULTS: EEG recordings were all within normal limits and showed no abnormalities. 3 of the 31 children showed mild mental disability and major physical disabilities at the age of 30 months. CONCLUSION: Single Infantile EEG recordings are of limited prognostic value for infants born with spina bifida. Serial EEG recordings in combination with other clinical or neurophysiological investigations might ameliorate the contributing predictive value of neonatal EEG.

Quantitative analysis of maturational changes in EEG background activity in very preterm infants with a normal neurodevelopment at 1 year of age.

BACKGROUND: The electroencephalographic (EEG) background pattern of preterm infants changes with postmenstrual age (PMA) from discontinuous activity to continuous activity. However, changes in discontinuity have been investigated by visual analysis only. AIM: To investigate the maturational changes in EEG discontinuity in healthy preterm infants using an automated EEG detection algorithm. STUDY DESIGN: Weekly 4h EEG recordings were performed in preterm infants with a gestational age (GA)<32weeks and normal neurological follow-up at 1year. The channel C3-C4 was analyzed using an algorithm which automatically detects periods of EEG inactivity (interburst intervals). The interburst-burst ratio (IBR, percentage of EEG inactivity during a moving time window of 600s) and mean length of the interburst intervals were calculated. Using the IBR, discontinuous background activity (periods with high IBR) and continuous background activity (periods with low IBR) were automatically detected and their mean length during each recording was calculated. Data were analyzed with regression and multivariate analysis. RESULTS: 79 recordings were performed in 18 infants. All recordings showed a cyclical pattern in EEG discontinuity. With advancing PMA, IBR (R(2)=0.64; p<0.001), interburst interval length (R(2)=0.43; p<0.001) and length of discontinuous activity (R(2)=0.38; p<0.001) decreased, while continuous activity increased (R(2)=0.50; p<0.001). Multivariate analysis showed that all EEG discontinuity parameters were equally influenced by GA and postnatal age. CONCLUSION: Analyzing EEG background activity in preterm infants is feasible with an automated algorithm and shows maturational changes of several EEG derived parameters. The cyclical pattern in IBR suggests brain organisation in preterm infant.

Quantitative analysis of amplitude-integrated electroencephalogram patterns in stable preterm infants, with normal neurological development at one year.

BACKGROUND: The amplitude-integrated EEG (aEEG) is feasible for monitoring cerebral activity in preterm infants. However, quantitative data on normal patterns in these infants are limited. OBJECTIVE: To study maturational aEEG changes in a cohort of stable preterm infants by automated quantification. METHODS: In a cohort of stable preterm infants with gestational age (GA) <32 weeks and normal neurological follow-up at 1 year, weekly 4 h EEG recordings were performed. aEEG traces were obtained from channel C(3)-C(4). The upper margin amplitude (UMA), lower margin amplitude (LMA) and bandwidth (BW) were quantitatively calculated using an expert software system. In addition, the relative duration of discontinuous background pattern (discontinuous background defined as activity with LMA <5 microV, expressed as DC-%) was calculated. RESULTS: 79 aEEG recordings (4-6 recordings/infant) were obtained in 18 infants. Analysis of the first week recordings demonstrated a strong positive correlation between GA and LMA, while DC-% decreased significantly. Longitudinally, all infants showed increase of LMA. Multivariate analysis showed that GA and postnatal age (PA) both contributed independently and equally to LMA and DC-%. We found a strong correlation between postmenstrual age (GA + PA) and LMA and DC-%, respectively. CONCLUSION: To our knowledge, this is the first study where aEEG development was studied by automated quantification of aEEG characteristics in a cohort of stable preterm infants with a normal neurological development at 1 year of age. LMA and DC-% are simple quantitative measures of neurophysiologic development and may be used to evaluate neurodevelopment in infants.

An algorithm for the automatic detection of seizures in neonatal amplitude-integrated EEG.

AIM: To develop and evaluate an algorithm for the automatic screening of electrographic neonatal seizures (ENS) in amplitude-integrated electroencephalography (aEEG) signals. METHODS: CFM recordings were recorded in asphyxiated (near)term newborns. ENS of at least 60 sec were detected based on their characteristic pattern in the aEEG signal, an increase of its lower boundary. The algorithm was trained using five CFM recordings (training set) annotated by a neurophysiologist, observer1. The evaluation of the algorithm was based on eight different CFM recordings annotated by observer1 (test set observer 1) and an independent neurophysiologist, observer2 (test set observer 2). RESULTS: The interobserver agreement between observer1 and 2 in interpreting ENS from the CFM recordings was high (G coefficient: 0.82). After dividing the eight CFM recordings into 1-min segments and classification in ENS or non-ENS, the intraclass correlation coefficient showed high correlations of the algorithm with both test sets (respectively, 0.95 and 0.85 with observer1 and 2). The algorithm showed in five recordings a sensitivity > or = 90% and approximately 1 false positive ENS per hour. However, the algorithm showed in three recordings much lower sensitivities: one recording showed ENSs of extremely high amplitude that were incorrectly classified by the algorithm as artefacts and two recordings suffered from low interobserver agreement. CONCLUSION: This study shows the feasibility of automatic ENS screening based on aEEG signals and may facilitate in the bed-side interpretation of aEEG signals in clinical practice.

[Turning the head, an unusual mechanism to compensate for diplopia caused by abduction restriction of one eye]. / Rotatie van het hoofd: een ongebruikelijke compensatie voor een abductiebeperking van één oog.

A 59-year-old-man visited the neurological outpatient clinic because of a leftward rotation of his head for the last 8 months. This head deviation turned out to represent a compensatory mechanism to alleviate diplopia that resulted from an abduction restriction of his left eye. By turning his head into the direction of the weak left lateral rectus muscle, the patient could fixate both eyes on target and maintain binocular vision.

Cobalamin supplementation improves cognitive and cerebral function in older, cobalamin-deficient persons.

BACKGROUND: Mild cobalamin (Cbl) deficiency is frequently found in older persons and is associated with cognitive and cerebral abnormalities. The effects of Cbl supplementation on these abnormalities are largely unknown. METHODS: In a single-blind, placebo-controlled intervention study, 16 healthy community-dwelling elderly subjects with low plasma Cbl concentration and no cognitive impairments were studied. Subjects underwent 1 month of treatment with placebo, followed by 5 months of treatment with intramuscular injections of hydroxycobalamin. Before and after measurements of plasma cobalamin, total homocysteine (tHcy), methylmalonic acid (MMA), quantitative electroencephalograph (qEEG), and psychometric tests were taken. RESULTS: After Cbl supplementation, plasma Cbl concentrations increased, and plasma MMA and tHcy concentrations decreased. The performance on the Verbal Word Learning Test, Verbal Fluency and Similarities improved. qEEG showed more fast activity and less slow activity. Lower plasma tHcy concentrations were related to increased fast activity on qEEG on the one hand and improved performance on the Verbal Word Learning Test and Similarities on the other. Increased fast or decreased slow activity on qEEG was associated with improved performance on the Verbal Word Learning Test, Similarities and Verbal Fluency. CONCLUSIONS: Electrographic signs of improved cerebral function and improved cognitive function were found after Cbl supplementation in older subjects with low plasma Cbl concentrations who were free of significant cognitive impairment. These improvements were related to a reduction of plasma tHcy concentration.

Clinical and biochemical effects of zileuton in patients with the Sjögren-Larsson syndrome.

UNLABELLED: The Sjögren-Larsson syndrome (SLS) is an inborn error of lipid metabolism, characterised clinically by congenital ichthyosis, mental retardation and spasticity. Patients also suffer from severe pruritus. The degradation of leukotriene (LT) B4 is one of the defective metabolic routes in SLS. Zileuton inhibits the synthesis of LTB4 and the cysteinyl leukotrienes. Five SLS patients were treated with zileuton for 3 months. Favourable effects were found on pruritus score (P = 0.006), general well-being, and background activity of electroencephalographic studies. Neuropsychological test results did not change significantly. There was, however, a clinically important trend towards improvement in the speed of information processing. Results of cerebral MRI and proton magnetic resonance spectroscopy did not change during therapy. Urinary concentrations of LTB4 and omega-OH-LTB4 decreased significantly (P=0.02 and P=0.003 respectively), while their concentrations in CSF were normal at baseline and remained so after therapy. CONCLUSION: Patients with Sjögren-Larsson syndrome might benefit from treatment with zileuton, especially with respect to the agonising pruritus. The findings reported here, point to a crucial role for leukotriene B4 in the pathogenesis of pruritus.

The maturation of auditory cortical evoked responses between (preterm) birth and 14 years of age.

In this study we report on the maturation of the auditory cortical evoked response (ACR) waveform between (preterm) birth and 14 years of age. From the results it can be concluded that the ACR waveform morphology shows substantial age-dependent changes until the age of 14 years. Two transitional periods could be recognized. The first between 36 and 41 weeks conceptional age; the second between 4 and 6 years of age. The adult waveform complex is achieved between 14 and 16 years of age. Further research is needed to determine whether these transitional periods in the maturation of ACRs correspond with important functional changes of the central auditory system.

EEG findings in patients with vascular parkinsonism.

OBJECTIVES: To investigate whether the conventional and quantitative EEGs of patients with vascular parkinsonism (VP) differ from those of idiopathic Parkinson's disease (PD) patients. MATERIAL AND METHODS: The EEGs of 13 patients with vascular parkinsonism and 14 patients with idiopathic Parkinson's disease were scored on a simple scale regarding aspects of conventional EEG variables. Alpha band power asymmetry and EEG slowing (increased delta and theta power) were calculated by the neurometrics method of quantitative EEG data evaluation. RESULTS: Analysis of both conventional and quantitative EEG data shows that VP patients had significantly less EEG slowing than PD patients. CONCLUSION: This study shows that the EEG in a group of patients with vascular parkinsonism differ from a patient group with idiopathic Parkinson's disease. Our results indicate that VP patients are not PD patients with subcortical vascular lesions, because then they would have had at least as much EEG slowing as PD patients.

Neonatal risk factors and risk scores including auditory evoked responses.

UNLABELLED: In a prospective study, 81 preterm infants and 25 healthy term infants were neurologically and neurophysiologically evaluated in the neonatal period. At 5-7 years of age the neurodevelopmental outcome was assessed. The validity and predictive value of the Neonatal Neurological Inventory (NNI) and the Neurobiological Risk Score (NBRS), including an additional gestational age factor (GAF) and an auditory evoked response factor (AERF) were assessed. Three of the 53 surviving preterm infants showed major neurological abnormalities at 5-7 years. Five infants showed neuropsychological abnormalities and 12 infants showed both neurological and neuropsychological abnormalities. An important subgroup of preterm infants could be identified as high-risk using the NNI and NBRS. The low sensitivity and negative predictive value resulted in a number of false-negative results. Logistic regression showed that intraventricular haemorrhage (IVH) and bilirubin levels contributed highly to the prediction of neurological outcome. For neuropsychological outcome these factors were IVH and assisted ventilation. Addition of the GAF and AERF as separate items to the NBRS did not affect the predictive power. Combined addition of the GAF and AERF showed improvement of both validity and predictive value. CONCLUSION: This study shows that IVH, bilirubin and assisted ventilation contribute most to the validity and predictive value of the NBRS. Furthermore, regarding neurological outcome addition of a GAF in combination with an AERF resulted in a substantial improvement of the validity and predictive value. The shortcomings of the current neonatal risk scores require a careful interpretation of clinical perinatal data regarding the prediction of neurodevelopmental outcome in preterm infants.

Neurodevelopmental profile in low-risk preterm infants at 5 years of age.

The goal of this study is to determine the neurodevelopmental profile of a group of low-risk preterm infants and to determine whether the potentially unfavourable outcome is due to a few infants with moderate to severe impairments or to a majority of infants with only slight impairments. In a prospective study 44 low-risk preterm infants, i.e. infants with a neonatal risk score indicating a favourable outcome, born between 25-34 weeks gestational age, and 18 healthy term infants were examined neurologically and tested neuropsychologically at 5 years of age. The more unfavourable outcome in the group of low-risk preterm infants compared with the term infants was largely attributable to a poorer outcome in 12 of the 44 low-risk preterm infants. The remaining low-risk preterm infants showed similar test scores compared with the term infants. From these results we conclude that the unfavourable neurodevelopmental outcome of low-risk preterm infants is due to moderate to severe impairment in a few low-risk preterm infants, rather than slight impairment in the majority. The low-risk preterm infants with an unfavourable outcome showed particular impairment on measures of visual-motor integration, concentration and auditory memory in combination with integrative functions.

Diagnostic and predictive value of auditory evoked responses in preterm infants: I. Patient characteristics and long-term neurodevelopmental outcome.

The diagnostic and predictive value of brainstem, middle latency, and cortical auditory evoked responses, obtained in the neonatal period, in 81 preterm infants was assessed in relation to neurodevelopmental outcome. Eighteen healthy term infants served as a control group. In this report the patient characteristics and neurodevelopmental outcome are presented. The preterm infants were neonatally classified according to risk category and gestational age. At 5 y of age the neurodevelopmental outcome was assessed based on neurologic and neuropsychologic evaluations. The neuropsychologic test results showed the highest IQ scores in term infants, intermediate IQ scores in low risk preterm infants, and lowest IQ scores in high risk preterm infants. The intermediate IQ scores in the low risk preterm group were due to significantly lower test scores in a small subgroup of low risk preterm infants. In a post hoc analysis 12 low risk preterm infants with an unfavorable outcome could be identified. The neuropsychologic test results of the remaining low risk infants showed no clear differences compared with the term infants. The results suggest that the unfavorable outcome of the low risk preterm group as a whole is due to moderate to severe impairment of the few, rather than slight impairment of the majority.

Diagnostic and predictive value of auditory evoked responses in preterm infants: II. Auditory evoked responses.

In this study, the diagnostic and predictive value of brainstem, middle latency, and cortical auditory evoked responses (BMC-AERs) obtained in the neonatal period in 81 preterm infants was assessed in relation to neurodevelopmental outcome. The preterm infants were neonatally classified according to risk category and gestational age. The BMC-AERs were analyzed with respect to detectability, latencies, and amplitudes as well as derived latency and amplitude measures. At 5 y of age the neurodevelopmental outcome was assessed from neurologic and neuropsychologic evaluations. The results showed that BMC-AER differences mainly correlated with risk category (low risk/high risk) and to some extent with degree of prematurity. In view of these findings the degree of prematurity and the effect of risk category have to be taken into account, when BMC-AERs are applied in the preterm period to predict neurodevelopmental outcome. In this study the BMC-AERs for infants with abnormal neurodevelopmental outcome were scarcely distinguishable from the BMC-AERs for infants with normal neurodevelopmental outcome. Thus far, this and previous reports have indicated that BMC-AERs in preterm infants are useful in maturational studies and with infants showing symptoms related to lesions or dysfunction of the peripheral and/or central auditory system. For predicting neurodevelopmental outcome in preterm infants, BMC-AERs are of limited clinical value.

Vaccination of dogs against Babesia canis infection.

This paper describes the clinico-pathological parameters measured in dogs that were vaccinated against Babesia canis using soluble parasite antigens (SPA) and then challenged. The packed cell volume (PCV) and the plasma creatinine value decreased immediately after challenge. Actual PCV values could be predicted in the first 5-6 days of the infection, assuming that creatinine values were modulated by increase of plasma volume. This association no longer existed after that time, and observations indicated splenic involvement in reduction of numbers of circulating erythrocytes. The anaemia due to B. canis infection appears to be the result of a multifactorial process including plasma volume increase, erythrocyte retention in the spleen and erythrocyte destruction, partly due to parasite proliferation. Vaccination limited the reduction of PCV values, and the development of splenomegaly. Differences in protection between vaccinated and control animals became apparent 6 days after infection, when a memory immune response becomes operative, and the onset of recovery of vaccinated animals correlated with the onset of antibody production against SPA.

The effects of early and late preterm birth on brainstem and middle-latency auditory evoked responses in children with normal neurodevelopment.

In preterm and term infants, brainstem and middle latency auditory evoked responses (ABR and MLR) were obtained at 40 and 52 weeks conceptional age (CA) and at 5 years of age. A neurological and neuropsychological evaluation was performed at 5 years of age. To study the effect of preterm birth on the maturation of the ABR and MLR, the preterm infants were divided into early and late preterm groups. Only children with a normal neurodevelopmental outcome at 5 years of age were entered into the study. For ABR, the late preterm group showed significantly longer mean latencies IIc, III, V, and Vc when compared with the term group at 52 weeks CA. There was a trend to longer ABR latencies I in the early preterm group compared with the term group. At 52 weeks CA, the late preterm group showed longer mean interpeak latencies III-I and V-I when compared with the term as well as the early preterm group. At 5 years, the late preterm group showed significantly longer mean ABR latencies IIc and III when compared to the early preterm group. For MLR, the early preterm group showed significantly longer mean latencies of MLR component PO when compared with the term group at 40 weeks CA. At 52 weeks, the late preterm group also had longer mean MLR latencies P0 than the term group. At 5 years of age, the term group showed higher mean peak-to-peak amplitudes Na-P0 than the early as well as the late preterm group. To a large extent, the ABR results support the hypothesis that middle ear effusions in combination with retarded myelination of the central auditory pathway are responsible for the ABR differences found between term and preterm infants with a normal neurodevelopmental outcome at 5 years of age. The longer latencies and interpeak latencies found in late preterm infants when compared with early preterm infants might be explained by an augmented vulnerability of the auditory pathway between 30 and 34 weeks CA. The MLR differences found between term and preterm infants might be explained by a difference in the maturation of primary and nonprimary MLR components.

Assessment of trigeminal nerve function by means of short-latency somatosensory evoked potentials after microneurosurgical repair.

In order to evaluate accurately trigeminal nerve damage and the response to microneurosurgical treatment, a reproducible, objective test of trigeminal nerve function is required. This study investigates the use of somatosensory evoked potentials as an objective monitor of trigeminal nerve function after microneurosurgical repair. We examined 10 patients, all but 1 treated for gnathic disorders, in whom a severe iatrogenic injury to the inferior alveolar nerve occurred unilaterally. One patient underwent partial mandibulectomy with sacrifice of the nerve because of a malignant tumour. A significant difference in trigeminal somatosensory evoked potential latencies after stimulation of the normal side of the lower jaw compared with the response after stimulation of the affected side was to be expected. Immediate microneurosurgical repair was carried out in 7 patients. The trigeminal somatosensory evoked potential latencies after right and left sided stimulation of the mandible did not differ significantly after subjective successful microneurosurgical repair. Somatosensory evoked potential testing appears to represent an objective method of evaluating trigeminal nerve function, in particular in relation to microneurosurgical procedures. The results of trigeminal testing should improve after technical refinement.