Peak detection in auditory and somatosensory evoked potentials by means of the zero-crossings wavelet representation

A feature detection algorithm for detecting singularity-like features in a one-dimensional signal has been developed. It is based on the zero-crossings wavelet representation introduced by Mallat [1], and involves a variance-weighted cross-correlation of the appropriate wavelet transform of the signal in the various frequency bands with an averaged template characterizing the particular feature. The algorithm was developed for the purpose of automatic feature detection in averaged evoked potentials. It successfully detects waves I to V in the auditory evoked potential and the N20 and P25 peaks in the median nerve stimulated somatosensory evoked potential, in normal and delayed-latency cases. The performance of the algorithm is plotted as a function of the signal-to-noise ratio. A priori knowledge of the expected feature amplitudes and latencies is not necessary, but may be incorporated into the model. By feeding the feature amplitude and latency estimates back into the algorithm as a priori knowledge, it is configured to track the changing characteristics of a feature over time.

Subdural recording of ictal DC shifts in neocortical seizures in humans

PURPOSE

Invasive ictal EEG recording is often necessary to delineate epileptogenic areas in patients with intractable partial epilepsy, but even intracranial ictal recordings often reveal ill-defined onset zones in neocortical epilepsy. We studied the physiologic significance of ictal direct current (DC) potentials recorded intracranially in human epilepsy.

METHODS

We made intracranial ictal EEG recordings in three patients with intractable partial seizures arising from frontal, lateral temporal, and parietal neocortical areas by using closely spaced subdural electrodes (platinum in two patients and stainless steel in one patient) with both standard (1.5 Hz) and open (0.016 Hz) low-frequency filter (LFF) settings.

RESULTS

The initial ictal pattern was localized to two to nine subdural electrodes and characterized by very low voltage and high-frequency rhythmic activity ("electrodecremental pattern"). A slow-rising negative potential (DC potential) was seen in a slightly more restricted area (two to six electrodes) and occurred 1-10 s before the initial ictal EEG discharges in two patients.

CONCLUSIONS

These results agree with those of previous studies of ictal DC shifts in animals and suggest that ictal DC shifts may be helpful in delineating the epileptogenic area more precisely in human epilepsy.

Ilizarov treatment of pilon fractures

The authors retrospectively reviewed 13 pilon fractures in 12 patients treated with a diaphyseal-epiphyseal technique of Ilizarov external fixation. Clinical followup averaged 16 months (range, 12-25 months). Eighty-four percent of the fractures had healed within 16 weeks after surgery. Average range of motion of the ankle was 12 degrees dorsiflexion and 25 degrees plantar flexion. One delayed union was treated with bone grafting and eventually healed; 1 nonunion was treated with ankle arthrodesis. Most patients (91%) experienced mild or no pain. There were no deep infections. This technique is an effective treatment option for tibial pilon fractures.

Subdural potentials at orbitofrontal and mesial prefrontal areas accompanying anticipation and decision making in humans: a comparison with Bereitschaftspotential

Field potentials associated with the execution of a warned choice Go/No-Go reaction task were recorded from prefrontal supplementary (SMA) and primary motor cortex (MI) by using subdural electrodes in 5 epileptic patients during presurgical evaluation. The choice was between a Go and a No-Go imperative stimulus (S2) in the S1-S2 paradigm. Orbitofrontal and mesial prefrontal areas generated a slow preceding potential before S2 (most likely late CNV), and bilateral mesial prefrontal areas generated a transient potential, most likely related to decision making, upon S2 in both Go and No-Go conditions. In self-paced, repetitive movement, the Bereitschaftspotential was seen only at SMA and MI, but not in the prefrontal area. The present result, therefore, suggests that in humans orbitofrontal and mesial frontal areas play an important role in preparation for cognition and in decision making, whereas SMA and MI do so in motor preparation.

Movement-related potentials associated with bilateral simultaneous and unilateral movements recorded from human supplementary motor area

To clarify the differences of movement-related potentials (MRPs) among ipsilateral, contralateral and simultaneous bilateral movements, MRPs with finger, thumb or foot movements were recorded from subdural electrodes chronically implanted on the supplementary motor area (SMA) in 3 patients, and also from the primary sensorimotor area in two of them being evaluated for epilepsy surgery. As a result: (1) SMA generated clear pre-movement potentials regardless of the type of movement. Its amplitude was almost identical between contralateral and bilateral movements except for the motor potential (MP). The pre-movement potentials associated with ipsilateral movements were relatively smaller than those with contralateral or bilateral movements. (2) The primary sensorimotor area generated clear pre-movement potentials in contralateral and bilateral movements with similar amplitude. With ipsilateral hand movements, however, only a small Bereitschaftspotential (BP) and no negative slope (NS') or MP was seen, and ipsilateral foot movements were not preceded by any BP. It is, therefore, most likely that, as far as the preparation for simple voluntary self-paced movement is concerned, the SMA plays an equally important role in unilateral and bilateral movements, whereas the primary sensorimotor area is involved predominantly in the preparation of contralateral movements.

Generator locations of movement-related potentials with tongue protrusions and vocalizations: subdural recording in human

Movement-related potentials (MRPs) associated with tongue protrusions and vocalizations were recorded from chronically implanted subdural electrodes over the lower perirolandic area in 7 patients being evaluated for epilepsy surgery. In 3 patients, tongue protrusions elicited a clearly defined, well localized slow negative Bereitschaftspotential (BP) at the motor tongue area, and a positive BP at the sensory tongue area. At the motor tongue area the negative BP was followed by a negative slope (NS') and a motor potential (MP), and at the sensory tongue area the positive BP and a positive reafferent potential (RAP) were seen but no NS' and MP could be identified. In the other 4 patients, tongue protrusions elicited positive BP, NS' and MP at the motor and sensory tongue area, and positive RAP at the sensory area. It was concluded that BPs, NS' and MPs are mainly generated in the motor cortex involving the crown as well as the anterior bank of the central fissure. The sensory cortex (areas 3a and 3b) also participated in the generation of BPs but to a lesser degree. Different degree of involvement of these multiple generators most likely explains the interindividual variability of polarity and distribution of the MRPs. RAPs most likely arise from primary sensory areas 1 and 2. Brain potentials were also recorded at the motor (2 patients) and sensory (2 patients) language areas, but no specific language-related potentials could be identified. Evoked potentials to lip stimulation were investigated in 4 patients. In 3 patients, the responses at the sensory tongue area (P16, N21 and P30) had the same latency but opposite polarity to those at the motor tongue area. In the other patient, the responses (P16, N21 and P30) at the motor and sensory tongue areas were of the same polarity. The MRPs to tongue protrusions in those 4 patients revealed the same polarity relationship between the pre- and postcentral potentials. However, the maximal amplitude of evoked potentials and MRPs was seen at almost the same electrodes, suggesting that the main generators for these MRPs and evoked potentials must be located at contiguous areas in the anterior and posterior bank, respectively, of the central fissure.

Delayed high median neuropathy after supracondylar humeral fracture. A case report and review of the literature

Compression neuropathy of the median nerve around the elbow is an uncommon yet well-recognized clinical entity. Acute compression can occur after trauma to the elbow, whereas prolonged compression neuropathy usually involves compression under a normal or aberrant anatomic structure. The authors present a case of severe median nerve compression neuropathy above the elbow that occurred several months after a supracondylar humeral fracture in a previously asymptomatic adolescent with aberrant soft tissue anatomy.

Polymerase chain reaction amplification of herpes simplex viral DNA from the geniculate ganglion of a patient with Bell's palsy

Bell's palsy is the most common cause of facial paralysis. In this study, we demonstrate the presence of herpes simplex viral type 1 (HSV-1) genomic DNA in the geniculate ganglion of a patient who had Bell's palsy. This association suggests that in this patient, HSV-1 may have caused Bell's palsy. If HSV-1 is a cause of Bell's palsy, treatment with acyclovir may be beneficial. Additional studies should be done to establish the prevalence of HSV-1 as an etiologic agent of Bell's palsy.

Pfeiffer's syndrome family tree. Review of the literature

Pfeiffer's syndrome is an autosomal dominant disorder characterized by craniofacial abnormalities and distal extremity abnormalities. This case study reviews four generations of a family with craniofacial abnormalities, multiple simple syndactylies, and delta phalanges of bilateral great toes and thumbs inherited in an autosomal dominant fashion.

Movement-related potentials associated with single and repetitive movements recorded from human supplementary motor area

To clarify the differences of movement-related potentials (MRPs) between single and repetitive movements, MRPs with finger movements were recorded from subdural electrodes chronically implanted on the supplementary motor area (SMA) in 2 patients, and MRPs with foot movements were recorded simultaneously from the SMA and the primary motor foot area in 1 patient. Repetitive movements did not elicit larger pre-movement potentials in the SMA as compared with single movements in all 3 patients. In the negative motor area, where electrical stimulation elicited inhibitory responses of voluntary movements and which is located at the rostral part of the SMA, pre-movement potentials to either single or repetitive movements were of approximately equal amplitude in 1 out of 3 patients. It is, therefore, most likely that the SMA plays an equally significant role in preparation for single and repetive voluntary movements.

EView--a workstation-based viewer for intensive clinical electroencephalography

We describe a workstation-based EEG viewer that satisfies the requirements for high-volume clinical EEG review. It currently supports two 24-h four-bed epilepsy monitoring units and a network of routine, intraoperative, and intensive care monitors, providing paperless review of over 5000 pages/day by a staff of clinical neurophysiologists. The design takes advantage of the development environment, processing and graphics resources, and networking capabilities of high-performance UNIX workstations. The user interface and operational infrastructure have been tailored to the demands of clinical neurophysiologists requiring rapid access to large volumes of EEG waveform data in a large clinical neurophysiology laboratory. This paper describes the functional requirements, system architecture, and implementation details of the current system.

Periodic limb movements and sleep apnoea

This study investigated the relationship of Periodic Leg Movements (PLMs) to the severity of Obstructive Sleep Apnoea (OSA) in 52 patients. In addition the prevalence of PLMs in OSA was compared with two other patient populations: narcolepsy and idiopathic PLM disorder (n = 38). All patients were between 20 and 50 years in age and were compared with a control group of 88 asymptotic paid volunteers aged between 20 and 50. PLMs were scored when tibialis anterior EMG activity lasted 0.5-5.0 s with an amplitude of at least half that of pre-sleep voluntary ankle dorsiflexion and when they were part of 4 or more consecutive events separated by 20-90 s. The prevalence of PLMs in OSA was 27.6%, which was similar to the prevalence in our normal controls of 20.5%. However, in the OSA group the majority of the PLMs occurred in the mild OSA patients (40.7%). This was similar to the prevalence of PLMs in narcoleptics (50%). The prevalence of PLMs in moderate OSA, was 24.5%; similar to that of normal controls. In severe OSA, PLMs were also low (12.5%). There is an inverse relationship between PLMs and the severity of OSA. The greater number of arousals and awakenings associated with respiratory irregularities seen in the severe OSA group produced an equivocal manifestation of PLMs.

Deformities of the forearm in patients who have multiple cartilaginous exostosis

Thirty-five patients who had multiple cartilaginous exostosis and deformities of the wrist and forearm were evaluated to determine the natural history and prognostic factors for the deformities. Radial and ulnar shortening were correlated linearly (r2 = 0.86), showing that both bones of the forearm were symmetrically involved. The angular growth abnormality of the distal aspect of the radius was correlated with radial shortening (r2 = 0.53) and ulnar shortening (r2 = 0.61), but it had no correlation with negative variance of the ulnar (r2 = 0.30). Carpal slip was an independent factor, with no correlation with any of the factors studied. The ulnar tether theory for deformities of the wrist in patients who have multiple cartilaginous exostosis was not substantiated by this study.

A data interchange standard for clinical neurophysiology

A Standard Specification for Transferring Digital Neurophysiological Data Between Independent Computer Systems (Designation E 1467-92) has been developed. The specification defines a common representation of all of the data associated with a complete clinical study, including digitized neurophysiological waveforms, textual annotations and interpretive reports. Patterned after existing, related healthcare data interchange standards, it will facilitate data interchange between neurophysiological instruments, computer systems within the neurophysiology laboratory, other information systems in the hospital, and outside healthcare facilities or research laboratories.

Data interchange for clinical neurophysiology

Clinical Neurophysiology is rapidly moving towards complete dependence on digital instrumentation and computer-based systems. ASTM E 1467-92 "Standard Specification for Transferring Digital Neurophysiological Data Between Independent Computer Systems" was developed to allow exchange of multichannel electrophysiological waveforms, embedded textual annotations, results of mathematical processing, and clinical interpretive reports between various instruments and systems. This will permit integration of the neurophysiology laboratory interaction with hospital and clinic informations systems, and sharing of data between institutions for clinical or research purposes.

Tumor necrosis factor and chemotherapeutic agents. Potentiation of cytotoxicity with interferon gamma

This study examined combinations of the recombinant human cytokines, tumor necrosis factor alpha and interferon gamma, with doxorubicin and dactinomycin as well as other drugs on six squamous cell carcinoma cell lines of head and neck origin using the 3(4,5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide proliferation assay. Interferon gamma significantly enhanced the cytotoxicity of tumor necrosis factor alpha with dactinomycin on all six cell lines investigated, while in four of six cell lines the cytotoxicity of tumor necrosis factor alpha with doxorubicin was significantly augmented by interferon gamma. Additional experiments showed no effect with either cytokine in combination with cisplatin, fluorouracil, methotrexate, or etoposide. These data demonstrate that human recombinant cytokines in concert with certain drugs improve in vitro cytotoxicity and may have a potential for improving in vivo therapy.