Electrophysiology in locked-in syndrome.
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Electroencephalography↗
Biomedical subjects
C W Hess
Publications and source records attributed to C W Hess.
Near cardiac death with onset in REM sleep: a polysomnographic case report.
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Aged↗
[Syncope of unclear origin--role of 2 diagnostic tests with high specificity].
We report the diagnostic evaluation of an elderly woman admitted with recurrent syncopes induced by head rotation. A cardiac origin was exclude by Holter ECG, echocardiography and carotid sinus compression. Angiography showed unilateral vertebral artery hypoplasia, suggesting the possibility of hemodynamic vertebrobasilar insufficiency. This origin, however, could be ruled out by monitoring of blood flow velocities in both posterior cerebral arteries with transcranial Doppler, which showed no alteration during syncope induced by head rotation. Detailed analysis of the course of the syncope recorded on videotape suggested a psychogenic event. Furthermore, the syncopes could be prevented with a "protective" placebo despite head rotation, and induced by a "provocative" placebo without head rotation while EEG monitoring showed normal brain activity. This finding underscored the suggestion of a psychogenic cause.
Aged↗
Hypersomnia following paramedian thalamic stroke: a report of 12 patients.
Paramedian thalamic stroke (PTS) is a cause of organic hypersomnia, which in the absence of systematic sleep-wake studies has been attributed to disruption of ascending activating impulses and considered a "dearoused" state. However, an increasing mount of data suggests a role of the thalamus in sleep regulation and raises the possibility that a sleep disturbance contributes to hypersomnia in PTS. We evaluated 12 patients with magnetic resonance imaging-proven isolated PTS and hypersomnia with 10 to >20 hours of sleep behavior per day. Nocturnal polysomnographic findings paralleled the severity of hypersomnia. All subjects had increased stage 1 NREM sleep, reduced stage 2 NREM sleep, and reduced numbers of sleep spindles. In patients with severe hypersomnia, slow-wave (stages 3-4) NREM sleep was often reduced, but there were no major REM sleep alterations. Daytime sleep behavior was associated mostly with stage 1 sleep by electroencephalogram; there was no correlation between hypersomnia and results of nap tests. We conclude that hypersomnia following PTS is accompanied by deficient arousal during the day and insufficient spindling and slow-wave sleep production at night. These observations support the hypothesis of a dual role of the paramedian thalamus as "final common pathway' for both maintenance of wakefulness and promotion of NREM sleep.
Adolescent↗
Blink reflex excitability is abnormal in patients with periodic leg movements in sleep.
The excitability of the late component of the blink reflex was measured in 19 patients with periodic leg movements in sleep (PLMS) and in 18 control patients with other sleep complaints. PLMS patients were not different from controls regarding age, body mass index, and apneas and hypopneas per hour of sleep. The latencies of the R1 and R2 components of the blink reflex were not different between the groups. However, in PLMS, the excitability of the R2 response was markedly enhanced: The second R2 response to a pair of stimuli given at an interval of 500 ms was in PLMS 59.5% (range 21-87%) of the first R2 response and in controls 18.8% (range 2-79%) (p < 0.0001, Mann-Whitney U test). These results provide further evidence of an altered motor control in PLMS, which is likely to be located subcortically and possibly related to the dopaminergic striatopallidal system.
Adult↗
Recordings of eye movements for stimulus control during fMRI by means of electro-oculographic methods.
A method for monitoring eye movements in humans during functional MRI is presented. It is based on the acquisition of electro-oculographic (EOG) signals near one eye. EOG potentials were amplified and converted into an optical signal just outside the head coil. An optical fiber was used for signal transmission from inside the magnet bore to the control room. The EOG sensor was tested during EPI sequences at 1.5 Tesla without contamination of the MR signal. Some flow related artifacts on the EOG were observed inside the magnet, but no additional interactions from the MR sequence. An analysis of the latency, direction, and amplitude of the saccadic eye movements was possible.
Electrooculography↗
The perception of movements elicited by magnetic cortex stimulation depends on the site of stimulation.
Previous reports suggest that magnetic cortical stimulation (MCS) of the motor cortex can elicit a sensation of movement (kinaesthesia) in paralysed limbs. To assess this sensory effect of MCS, we examined the accuracy of kinaesthetic perception of stimulus-induced right elbow flexion in six blindfolded, healthy subjects. Matching of movements elicited by MCS was compared with matching of passive elbow movements. Small flexion movements between 1.5 and 5 degrees of angle were regularly overestimated by 50-100% when induced by MCS over the parietal cortex, whereas movements elicited by MCS over the frontal cortex or by passive elbow flexion were accurately estimated. Our results provide data compatible with the hypothesis of the existence of a "central sense of movement". Activation of collateral branches projecting from the motor cortex to the sensory could be the underlying mechanism to this phenomenon.
Adult↗
Encephalopathy associated with Hashimoto thyroiditis: diagnosis and treatment.
Six patients with Hashimoto thyroiditis (HT) and associated encephalopathy (HE) are described and compared with 14 well-documented cases retrieved from the literature. HE typically affects patients when they are euthyroid and, in an appropriate clinical situation, antithyroid autoantibodies are the main indicators of HE. Since clinical features of HE are unspecific, other aetiologies such as infectious, metabolic, toxic, vascular, neoplastic, and paraneoplastic causes have to be excluded. Our own six cases and those from the literature show that two types of initial clinical presentation can be differentiated: a vasculitic type with stroke-like episodes and mild cognitive impairment in nine patients, and a diffuse progressive type with dementia, seizures, psychotic episodes or altered consciousness in 11 patients. These types may overlap, particularly in the long-term course without treatment. Response to steroids was usually excellent with complete remission in 80%. Eighteen of the 20 patients were women. Characteristic, though unspecific, findings were abnormal EEG (90%) and CSF (80%). Together with quantitative neuropsychological testing, these proved sensitive for monitoring the efficacy of therapy. Conversely, antithyroid autoantibody titres did not correlate with the severity or type of clinical presentation. The link between HE and HT is not clear. A pathogenetic role for antithyroid autoantibodies in the central nervous system seems unlikely.
Adult↗
Memory without context: amnesia with confabulations after infarction of the right capsular genu.
OBJECTIVE: To explore the mechanism of an amnesia marked by confabulations and lack of insight in a patient with an infarct of the right inferior capsular genu. The confabulations could mostly be traced back to earlier events, indicating that the memory disorder ensued from an inability to store the temporal and spatial context of information acquisition rather than a failure to store new information. METHODS: To test the patient's ability to store the context of information acquisition, two experiments were composed in which she was asked to decide when or where she had learned the words from two word lists presented at different points in time or in different rooms. To test her ability to store new information, two continuous recognition tests with novel non-words and nonsense designs were used. Recognition of these stimuli was assumed to be independent of the context of acquisition because the patient could not have an a priori sense of familiarity with them. RESULTS: The patient performed at chance in the experiments probing knowledge of the context of information acquisition, although she recognised the presented words almost as well as the controls. By contrast, her performance was normal in the recognition tests with non-words and nonsense designs. CONCLUSION: These findings indicate that the patient's amnesia was based on an inability to store the context of information acquisition rather than the information itself. Based on an analysis of her lesion, which disconnected the thalamus from the orbitofrontal cortex and the amygdala, and considering the similarities between her disorder, Wernicke-Korsakoff syndrome, and the amnesia after orbitofrontal lesions, it is proposed that contextual amnesia results from interruption of the loop connecting the amygdala, the dorsomedial nucleus, and the orbitofrontal cortex.
Amnesia↗
Early prognosis in coma after cardiac arrest: a prospective clinical, electrophysiological, and biochemical study of 60 patients.
BACKGROUND: The univariate study of clinical, electrophysiological, or biochemical variables has been shown to predict the outcome in postanoxic coma in about 50% of patients for each type of variable. Previous studies did not, however, consider the prognostic accuracy of a multivariate approach. METHODS: Sixty patients in coma for more than six hours after cardiac arrest were prospectively examined by means of repeated clinical examinations (including Glasgow coma score (GCS)), EEG, and medianus nerve somatosensory evoked potentials (SEPs). In 16 patients, the early concentrations of serum neuron specific enolase and ionised calcium were also measured. RESULTS: Within the first year after cardiac arrest, 20% of patients made a good neurological recovery; 80% remained in a vegetative state or died. Clinical examination correctly predicted outcome in 58% of patients, SEP in 59%, and EEG in 41%. The combination of clinical examination, SEP, and EEG raised the percentage of correct predictions to 82%, without false pessimistic predictions. Concentrations of serum neuron specific enolase and ionised calcium were of no additional prognostic help. Multivariate regression analysis identified the association of GCS < 8 at 48 hours with abnormal or absent early cortical SEPs as highly predictive of a bad outcome (risk = 97%, 95% confidence interval = 86-99%). CONCLUSION: The combination of GCS at 48 hours, SEP, and if these are non-conclusive, EEG, permits a more reliable prediction of outcome in postanoxic coma than clinical examination alone.
Adult↗
Autoantibody-associated sensory neuronopathy and intestinal pseudo-obstruction without detectable neoplasia.
A 60-year-old patient presenting with the typical features of progressive sensory neuronopathy and subsequent intestinal pseudo-obstruction was found to have antineuronal nuclear antibodies (ANNA-I or Anti-Hu). These findings were suggestive of a paraneoplastic syndrome, but neither clinically nor at autopsy could a neoplasm be detected. Neuropathological findings were identical with those known for carcinoma-associated forms with marked neuron loss of spinal sensory ganglia and myenteric plexus. Therefore, ANNA-I and intestinal pseudo-obstruction may in rare cases occur without detectable underlying cancer.
Antibodies, Antinuclear↗
Measuring linguistic development in a child adopted from Romania.
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Adoption↗
[Sleep disorders in childhood].
Sleep disorders in childhood are frequent and usually harmless. They rarely point to a serious disease. Difficulty in falling asleep and nightly awakenings are age-dependent and transitory. While the largely harmless somnambulism and pavor nocturnus occur in the deep sleep of the first third of the night, the anxiety dreams of REM sleep appear preferentially in the second half of the night. Other disorders such as nocturnal enuresis and talking in sleep may occur during the whole night. It is very important to inform the parents because this helps to counter fears and false expectations. Consistent sleep hygiene needs to be developed with avoidance of irregular sleep rhythm and an unrestful sleep environment. Sometimes it is necessary to learn new behaviour patterns with the child. Only exceptionally is drug therapy indicated. However, nocturnal breathing disorders and nocturnal epilepsy do have a pathological significance and need specific therapy. In order to clarify the reasons for sleep disorders, it is necessary to keep a sleep diary, to undertake specific examinations (e.g. psychological, pneumological, neurological, urological, otorhinolaryngological and possibly using diagnostic equipment such as video-polysomnography).
Cataplexy↗
Sensitivity and specificity of needle electromyography: a prospective study comparing automated interference pattern analysis with single motor unit potential analysis.
In this prospective study, automated interference pattern analysis (IPA, "Willison analysis", modified by Stålberg et al. 1983) was compared to the quantitative evaluation of mean motor unit potential duration (QMUP) in 239 muscles from consecutive, unselected patients. The sensitivity and specificity of both methods were calculated with respect to the clinically derived final neurological diagnosis, with histology available for 120 examinations. Whereas specificities were not different for the methods, the sensitivity for detection of abnormal vs. normal was 49% for QMUP and 74% for IPA (P < 0.001). The sensitivity for detection of myopathy or neuropathy was 46% or 38% for QMUP and 75% (P < 0.001) or 53% (P < 0.05) for IPA. Thus, in all instances, IPA had superior sensitivity with unchanged specificity as compared to QMUP. The results of a rapid and purely qualitative visual MUP assessment were statistically not different from QMUP. Although widely used, neither of these methods has been evaluated for its reliability in unselected patients with various grades of disease. Our results indicate that in a routine setting, the best diagnostic strategy might be the automated IPA, which can be quickly obtained in several muscles, followed by muscle biopsy in unclear cases.
Adolescent↗
Electrophysiological characteristics of lesions in facial palsies of different etiologies. A study using electrical and magnetic stimulation techniques.
Using magnetic stimulation techniques in addition to conventional electrical stimulation, the entire facial motor pathway can be assessed electrophysiologically. To study the diagnostic yield of these examinations, 174 patients with facial palsies of a variety of etiologies were examined (85 Bell's palsies, 24 Guillain-Barré syndrome (GBS), 19 Lyme borreliosis, 17 zoster oticus, 12 meningeal affections, 10 brain-stem disorders and 7 HIV-related facial palsies). The facial nerve was stimulated electrically at the stylomastoid fossa and magnetically within its canalicular portion. Additionally, the face-associated contralateral motor cortex was stimulated magnetically. Recordings were from the nasalis or mentalis muscle, or both, using surface electrodes. Bell's palsy patients showed typically a unilateral local hypoexcitability of the facial nerve to canalicular stimulation. In GBS, bilateral latency prolongations were frequent, as expected for a myelinic disorder. In contrast, in zoster, predominant axonotmesis was unilateral, and in HIV infection sometimes bilateral. The method was very sensitive to detect subclinical dysfunctions in meningo-radiculitis and malignant meningeal diseases, either prior to the onset of palsy, or on the contralateral (clinically unaffected) side. It also distinguished reliably between central and peripheral facial motor pathway lesions. In our experience, these inexpensive and non-invasive electrophysiological techniques contribute substantially to the differential diagnosis of facial palsies.
Adult↗
Motion imagery in Parkinson's disease.
Patients with Parkinson's disease fail to fully profit from advance information about a target's movement in tracking tasks, possibly indicating deficient anticipation of the target's movement. Time estimation has been claimed to be deficient in Parkinson's disease. On the background of these studies, we tested the hypothesis that motion imagery is impaired in Parkinson's disease. Eleven non-demented patients with Parkinson's disease and nine age-matched controls participated in experiments testing their ability to anticipate trajectories of moving points (prediction whether two moving points would crash or not) and to estimate the time needed for completion of an invisible target's movement (a point moving around a circle). In addition, mirror drawing, a task involving motor learning and adjustment of movement to incongruent visual feedback, was tested. The Parkinson's disease patients, who failed to improve on mirror drawing, were not impaired on the imagery tasks: they estimated movement time and predicted trajectories with equal precision as the controls. Motion imagery thus appears to be intact in Parkinson's disease. However, Parkinson's disease patients did not accelerate their predictions of trajectories with practice as fast as the controls, a deficit which may be interpreted in terms of the fronto-striatal dysfunction repeatedly demonstrated in Parkinson's disease.
Aged↗
Diagnostic value of paraclinical tests in multiple sclerosis: relative sensitivities and specificities for reclassification according to the Poser committee criteria.
The yield of paraclinical tests was evaluated in a prospective study of 189 consecutive patients referred for suspected multiple sclerosis (142 patients with multiple sclerosis, 47 non-multiple sclerosis patients on discharge). Patients were first classified according to the Poser criteria by the clinical findings. Subsequently, the results of paraclinical tests (cranial MRI, visually evoked potentials (VEPs), somatosensory evoked potentials by tibial nerve stimulation (SSEPs), motor evoked potentials (MEPs), and analysis of CSF for oligoclonal banding and IgG-index (CSF)) were taken into account. The percentage of reclassified patients (reclassification sensitivity, RS) was always lower than the percentage of abnormal results (diagnostic sensitivity, DS), and the divergence of RS v DS differed between the tests (60% v 84% in MRI, 31% v 77% in CSF, 29% v 37% in VEPs, 20% v 68% in MEPs, and 12% v 46% in SSEPs respectively). False reclassifications of non-multiple sclerosis patients to multiple sclerosis would have occurred with all tests (MRI: six of 47 patients, (reclassification specificity 88%); CSF: one (98%); VEPs: two (96%); MEPs: two (96%); SSEPs: four (91%); P < 0.05). Although MRI had superior diagnostic capacity, 57 of the 142 patients with multiple sclerosis were not reclassified by the MRI result, 12 of whom were reclassified by CSF and 18 by one of the evoked potential (EP) studies. Of the 98 patients not reclassified by CSF, 53 were reclassified by MRI and 39 by EPs. The results suggest that for the evaluation of paraclinical tests in suspected multiple sclerosis, comparison of diagnostic sensitivities is inappropriate. In general, a cranial MRI contributes most to the diagnosis; however, due to its comparatively low specificity and its considerable number of negative results, EP or CSF studies are often useful to establish the diagnosis of multiple sclerosis.
Adolescent↗
Electrophysiological assessment of functional corpus callosum integrity in internal hydrocephalus.
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Corpus Callosum↗